Astrophysics
New submissions
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New submissions for Fri, 15 Nov 19
- [1] arXiv:1911.05736 [pdf, other]
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Title: Constraining the abundance of primordial black holes with gravitational lensing of gravitational waves at LIGO frequenciesAuthors: Jose M. DiegoComments: 18 pages and 15 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
Gravitational waves from binary black holes that are gravitationally lensed can be distorted by small microlenses along the line of sight. Microlenses with masses of a few tens of solar masses, and that are close to a critical curve in the lens plane, can introduce a time delay of a few millisecond. Such time delay would result in distinctive interference patterns in the gravitational wave that can be measured with current experiments such as LIGO/Virgo. We consider the particular case of primordial black holes with masses between 5 and 50 solar masses acting as microlenses. We study the effect of a population of primordial black holes constituting a fraction of the dark matter, and contained in a macrolens (galaxy or cluster), over gravitational waves that are being lensed by the combined effect of the macrolens plus microlenses. We find that at the typical magnifications expected for observed GW events, the fraction of dark matter in the form of compact microlenses, such as primordial black holes, can be constrained to percent level. Similarly, if a small percentage of the dark matter is in the form of microlenses with a few tens of solar masses, at sufficiently large magnification factors, all gravitational waves will show interference effects. These effects could have an impact on the inferred parameters. The effect is more important for macroimages with negative parity, which usually arrive after the macroimages with positive parity.
- [2] arXiv:1911.05743 [pdf]
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Title: High Resolution Imaging in the Visible with Faint Reference Stars on Large Ground-Based TelescopesAuthors: Craig MackayComments: 32 pages, 16 figures, 18 tables. Preprint of article since accepted for publication 13 November 2019 in Journal of Astronomical InstrumentationSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Astronomers working with faint targets will benefit greatly from improved image quality on current and planned ground-based telescopes. At present, most adaptive optic systems are targeted at the highest resolution with bright guide stars. We demonstrate a significantly new approach to measuring low-order wavefront errors by using a pupil-plane curvature wavefront sensor design. By making low order wavefront corrections we can deliver significant improvements in image resolution in the visible on telescopes in the 2.5m to 8.2m range on good astronomical sites. As a minimum the angular resolution will be improved by a factor of 2.5 to 3 under any reasonable conditions and, with further correction and image selection, even sharper images may be obtained routinely. We re-examine many of the assumptions about what may be achieved with faint reference stars to achieve this performance. We show how our new design of curvature wavefront sensor combined with wavefront fitting routines based on radon transforms allow this performance to be achieved routinely. Simulations over a wide range of conditions match the performance already achieved in runs with earlier versions of the hardware described. Reference stars significantly fainter than I 17m may be used routinely to produce images with a near diffraction limited core and halo much smaller than that delivered by natural seeing.
- [3] arXiv:1911.05744 [pdf, other]
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Title: Zodiacal Exoplanets in Time (ZEIT) IX: a flat transmission spectrum and a highly eccentric orbit for the young Neptune K2-25b as revealed by SpitzerAuthors: Pa Chia Thao, Andrew W. Mann, Marshall C. Johnson, Elisabeth R. Newton, Xueying Guo, Isabel J. Kain, Aaron C. Rizzuto, Paul A. Dalba, Eric Gaidos, Jonathan M. Irwin, Adam L. KrausComments: 20 pages, 5 figures, 6 tables. Accepted for publication in The Astronomical JournalSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Transiting planets in nearby young clusters offer the opportunity to study the atmospheres and dynamics of planets during their formative years. To this end, we focused on K2-25b -- a close-in (P=3.48 days), Neptune-sized exoplanet orbiting a M4.5 dwarf in the 650Myr Hyades cluster. We combined photometric observations of K2-25 covering a total of 44 transits and spanning >2 years, drawn from a mix of space-based telescopes (Spitzer Space Telescope and K2) and ground-based facilities (Las Cumbres Observatory Network and MEarth). The transit photometry spanned 0.6 to 4.5$\mu$m, which enabled our study of K2-25b's transmission spectrum. We combined and fit each dataset at a common wavelength within an MCMC framework, yielding consistent planet parameters. The resulting transit depths ruled out a solar-composition atmosphere for K2-25b for the range of expected planetary masses and equilibrium temperature at a $>4\sigma$ confidence level, and are consistent with a flat transmission spectrum. Mass constraints and transit observations at a finer grid of wavelengths (e.g., from HST) are needed to make more definitive statements about the presence of clouds or an atmosphere of high mean-molecular weight. Our precise measurements of K2-25b's transit duration also enabled new constraints on the eccentricity of K2-25's orbit. We find K2-25b's orbit to be eccentric (e>0.20) for all reasonable stellar densities and independent of the observation wavelength or instrument. The high eccentricity is suggestive of a complex dynamical history and motivates future searches for additional planets or stellar companions.
- [4] arXiv:1911.05745 [pdf, other]
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Title: A closer look at the spur, blob, wiggle, and gaps in GD-1Comments: Submitted to MNRAS. comments are very welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
The GD-1 stream is one of the longest and coldest stellar streams discovered to date, and one of the best objects for constraining the dark matter properties of the Milky Way. Using data from {\it Gaia} DR2 we study the proper motions, distance, morphology and density of the stream to uncover small scale perturbations. The proper motion cleaned data shows a clear distance gradient across the stream, ranging from 7 to 12 kpc. However, unlike earlier studies that found a continuous gradient, we uncover a distance minimum at $\varphi_{1}\approx$-50 deg, after which the distance increases again. We can reliably trace the stream between -85$<\varphi_{1}<$15 deg, showing an even further extent to GD-1 beyond the earlier extension of \citet{Price-Whelan18a}. We constrain the stream track and density using a Boolean matched filter approach and find three large under densities and find significant residuals in the stream track lining up with these gaps. In particular, a gap is visible at $\varphi_{1}$=-3 deg, surrounded by a clear sinusoidal wiggle. We argue that this wiggle is due to a perturbation since it has the wrong orientation to come from a progenitor. We compute a total initial stellar mass of the stream segment of 1.58$\pm$0.07$\times$10$^{4}$ M$_{\odot}$. With the extended view of the spur in this work, we argue that the spur may be unrelated to the adjacent gap in the stream. Finally, we show that an interaction with the Sagittarius dwarf can create features similar to the spur.
- [5] arXiv:1911.05746 [pdf, other]
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Title: Galaxy Formation with BECDM -- II. Cosmic Filaments and First GalaxiesAuthors: Philip Mocz (Princeton), Anastasia Fialkov, Mark Vogelsberger, Fernando Becerra, Xuejian Shen, Victor H. Robles, Mustafa A. Amin, Jesús Zavala, Michael Boylan-Kolchin, Sownak Bose, Federico Marinacci, Pierre-Henri Chavanis, Lachlan Lancaster, Lars HernquistComments: 19 pages, 12 figures, submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
Bose-Einstein Condensate Dark Matter (BECDM; also known as Fuzzy Dark Matter) is motivated by fundamental physics and has recently received significant attention as a serious alternative to the established Cold Dark Matter (CDM) model. We perform cosmological simulations of BECDM gravitationally coupled to baryons and investigate structure formation at high redshifts ($z \gtrsim 5$) for a boson mass $m=2.5\cdot 10^{-22}~{\rm eV}$, exploring the dynamical effects of its wavelike nature on the cosmic web and the formation of first galaxies. Our BECDM simulations are directly compared to CDM as well as to simulations where the dynamical quantum potential is ignored and only the initial suppression of the power spectrum is considered -- a Warm Dark Matter-like ("WDM") model often used as a proxy for BECDM. Our simulations confirm that "WDM" is a good approximation to BECDM on large cosmological scales even in the presence of the baryonic feedback. Similarities also exist on small scales, with primordial star formation happening both in isolated haloes and continuously along cosmic filaments; the latter effect is not present in CDM. Global star formation and metal enrichment in these first galaxies are delayed in BECDM/"WDM" compared to the CDM case: in BECDM/"WDM" first stars form at $z\sim 13$/$13.5$ while in CDM star formation starts at $z\sim 35$. The signature of BECDM interference, not present in "WDM", is seen in the evolved dark matter power spectrum: although the small scale structure is initially suppressed, power on kpc scales is added at lower redshifts. Our simulations lay the groundwork for realistic simulations of galaxy formation in BECDM.
- [6] arXiv:1911.05748 [pdf, other]
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Title: Stellar population models based on the SDSS-IV MaStar library of stellar spectra. I. Intermediate-age/old modelsAuthors: C. Maraston, L. Hill, D. Thomas, R. Yan, Y. Chen, J. Lian, T. Parikh, S. Meneses-Goytia, M. Bershady, N. Drory, D. Bizyaev, A. Concas, J. Brownstein, D. Lazarz, G. Stringfellow, K. StassunComments: 38 pages, 31 figures, submitted to The Monthly Notices of the Royal Astronomical SocietySubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We use the first release of the SDSS/MaStar stellar library comprising 8646, high (>50) S/N spectra, to calculate integrated spectra of stellar population models. The model spectra cover the wavelength range 0.36-1.03 micron and share the same spectral resolution (R=1800) and flux calibration as the SDSS-IV/MaNGA galaxy data. The parameter space covered by the stellar spectra collected thus far allows the calculation of models with chemical composition -2 <= [Z/H] <= + 0.35 and ages larger than ~200 Myr. These ranges will be extended as MaStar collects further data. Notably, we are able to include spectra for dwarf Main Sequence (MS) stars close to the core H-burning limit of 0.1 Msun. We are also able to include the contribution of cold and metal-rich giants, which manifest themselves with strong absorption bands between 7000 and 10,000 Angstrom. These features will be important for modelling the spectra of massive galaxies. Other novelties include better coverage of the HR diagram at low-metallicity, where we can calculate models as young as 500 Myr. Additionally, we fully include the Blue Horizontal Branch phase. We present models adopting two sets of stellar parameters (T_{eff}, logg, [Z/H]). In a novel approach, the reliability of stellar parameters is tested 'on the fly' using the stellar population models themselves. We test the age and metallicity scale of the new models with Milky Way and Magellanic Clouds GCs with independently measured age and chemical composition. We find that the new MaStar-based models are able to recover ages and metallicities remarkably well, with systematics as low as a few percent for calibration sets with homogeneously derived ages and metallicities. We also fit a MaNGA galaxy spectrum, finding that the new models gain fitting residuals of the order of a few percent comparable to the state-of-art models, but now over a wider wavelength range.
- [7] arXiv:1911.05751 [pdf, other]
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Title: Cosmology dependence of galaxy cluster scaling relationsComments: 14 pages, 7 figures, 8 tables. Submitted to MNRAS. Comments are welcome. Abstract abridgedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The abundance of galaxy clusters as a function of mass and redshift is a well known powerful cosmological probe, which relies on underlying modelling assumptions on the mass-observable relations (MOR). MOR parameters have to be simultaneously fit together with the parameters describing the cosmological model. Some of the MOR parameters can be constrained directly from multi-wavelength observations, as the normalization at some reference cosmology, the mass-slope, the redshift evolution and the intrinsic scatter. However, the cosmology dependence of MORs cannot be tested with multi-wavelength observations alone. We use Magneticum simulations to explore the cosmology dependence of galaxy cluster scaling relations. We run fifteen different hydro-dynamical cosmological simulations varying $\Omega_m$, $\Omega_b$, $h_0$ and $\sigma_8$ (around a reference cosmological model). The MORs considered in this work are gas mass, gas temperature, Y and velocity dispersion as a function of the spherical overdensity virial mass. We verify that the mass and redshift slopes and the intrinsic scatter of the MORs are nearly independent of cosmology with variations significantly smaller than current observational uncertainties. We show that the gas mass sensitively depends only on the baryon fraction, velocity dispersion and gas temperature sensitively depend on the hubble constant, and Y depends on both baryon fraction and the hubble constant. We investigate the cosmological implications of our MOR parameterization on a mock catalog created for an idealized eROSITA-like experiment. We show that our parametrization introduces a strong degeneracy between the cosmological parameters and the normalization of the MOR, degeneracy that can be broken by combining multiple observables and hence improve the cosmological parameter constraints.
- [8] arXiv:1911.05753 [pdf, other]
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Title: The Cloud Factory I: Generating resolved filamentary molecular clouds from galactic-scale forcesAuthors: Rowan J. Smith, Robin G. Treß, Mattia C. Sormani, Simon C.O. Glover, Ralf S. Klessen, Paul C. Clark, Andrés F. Izquierdo, Ana Duarte CabralComments: 20 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
We introduce a new suite of simulations, "The Cloud Factory", which self-consistently forms molecular cloud complexes at high enough resolution to resolve internal substructure (up to 0.25 Msol in mass) all while including galactic-scale forces. We use a version of the Arepo code modified to include a detailed treatment of the physics of the cold molecular ISM, and an analytical galactic gravitational potential for computational efficiency. The simulations have nested levels of resolution, with the lowest layer tied to tracer particles injected into individual cloud complexes. These tracer refinement regions are embedded in the larger simulation so continue to experience forces from outside the cloud. This allows the simulations to act as a laboratory for testing the effect of galactic environment on star formation. Here we introduce our method and investigate the effect of galactic environment on filamentary clouds. We find that cloud complexes formed after a clustered burst of feedback, have shorter lengths and are less likely to fragment compared to quiescent clouds (e.g. the Musca filament) or those dominated by the galactic potential (e.g. Nessie). Spiral arms and differential rotation preferentially align filaments, but strong feedback randomises them. Long filaments formed within the cloud complexes are necessarily coherent with low internal velocity gradients, which has implications for the formation of filamentary star-clusters. Cloud complexes formed in regions dominated by supernova feedback have fewer star-forming cores, and these are more widely distributed. These differences show galactic-scale forces can have a significant impact on star formation within molecular clouds.
- [9] arXiv:1911.05756 [pdf, other]
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Title: Can astrophysical neutrinos trace the origin of the detected ultra-high energy cosmic rays?Comments: 11 pages, 5 figures, to be submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Since astrophysical neutrinos are produced in the interactions of cosmic rays, identifying the origin of cosmic rays using directional correlations with neutrinos is one of the most interesting possibilities of the field. For that purpose, especially the Ultra-High Energy Cosmic Rays (UHECRs) are promising, as they are deflected less by extragalactic and Galactic magnetic fields than cosmic rays at lower energies. However, photo-hadronic interactions of the UHECRs limit their horizon, while neutrinos do not interact over cosmological distances. We study the possibility to search for anisotropies by investigating neutrino-UHECR correlations from the theoretical perspective, taking into account the UHECR horizon, magnetic-field deflections, and the cosmological source evolution. Under the assumption that the neutrinos and UHECRs all come from the same source class, we demonstrate that the non-observation of neutrino multiplets strongly constrains the possibility to find neutrino-UHECR correlations.
- [10] arXiv:1911.05760 [pdf, other]
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Title: Flyby-induced misalignments in planet-hosting discsComments: Accepted for publication in MNRAS. 9 pages with 6 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
We now have several observational examples of misaligned broken protoplanetary discs, where the disc inner regions are strongly misaligned with respect to the outer disc. Current models suggest that this disc structure can be generated with an internal misaligned companion (stellar or planetary), but the occurrence rate of these currently unobserved companions remains unknown. Here we explore whether a strong misalignment between the inner and outer disc can be formed without such a companion. We consider a disc that has an existing gap --- essentially separating the disc into two regions --- and use a flyby to disturb the discs, leading to a misalignment. Despite considering the most optimistic parameters for this scenario, we find maximum misalignments between the inner and outer disc of $\sim$45$^{\circ}$ and that these misalignments are short-lived. We thus conclude that the currently observed misaligned discs must harbour internal, misaligned companions.
- [11] arXiv:1911.05763 [pdf, other]
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Title: Capturing Non-Gaussianity of the Large-Scale Structure with Weighted Skew-SpectraSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
The forthcoming generation of wide-field galaxy surveys will probe larger volumes and galaxy densities, thus allowing for a much larger signal-to-noise ratio for higher-order clustering statistics, in particular the galaxy bispectrum. Extracting this information, however, is more challenging than using the power spectrum due to more complex theoretical modeling, as well as significant computational cost of evaluating the bispectrum signal and the error budget. To overcome these challenges, several proxy statistics have been proposed in the literature, which partially or fully capture the information in the bispectrum, while being computationally less expensive than the bispectrum. One such statistics are {\it weighted skew-spectra}, which are cross-spectra of the density field and appropriately weighted quadratic fields. Using Fisher forecasts, we show that the information in these skew-spectra is equivalent to that in the bispectrum for parameters that appear as amplitudes in the bispectrum model, such as galaxy bias parameters or the amplitude of primordial non-Gaussianity. We consider three shapes of the primordial bispectrum: local, equilateral and that due to massive particles with spin two during inflation. To obtain constraints that match those from a measurement of the full bispectrum, we find that it is crucial to account for the full covariance matrix of the skew-spectra.
- [12] arXiv:1911.05765 [pdf, other]
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Title: Constraints on the Engines of Fast Radio BurstsComments: comments welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We model the sample of fast radio bursts (FRB), including the newly discovered CHIME repeaters, using the synchrotron blast wave model of Metzger, Margalit & Sironi (2019). This model postulates that FRBs are precursor radiation from ultra-relativistic magnetized shocks generated as flare ejecta from a central engine collide with an effectively stationary external medium. Downward drifting of the burst frequency structure naturally arises from deceleration of the blast-wave. The data are consistent with FRBs being produced by flares of energy $E_{\rm flare} \sim 10^{43}-10^{46}(f_{\xi}/10^{-3})^{-4/5}$ erg, where $f_{\xi}$ is the maser efficiency, and minimum bulk Lorentz factors $\Gamma \approx 10^2-10^3$, which generate the observed FRBs at shock radii $r_{\rm sh} \sim 10^{12}-10^{13}$ cm. We infer upstream densities $n_{\rm ext}(r_{\rm sh}) \sim 10^{2}-10^{4}$ cm$^{-3}$ and radial profiles $n_{\rm ext} \propto r^{-k}$ showing a range of slopes $k \approx [-2,1]$ (which are seen to evolve between bursts), broadly consistent with the upstream medium being the inner edge of an ion-loaded shell released by a recent energetic flare. The burst timescales, energetics, rates, and external medium properties are consistent with repeating FRBs arising from young, hyper-active flaring magnetars, but the methodology presented is generally applicable to any central engine which injects energy impulsively into a dense magnetized medium. Uncertainties and variations of the model are discussed, including the effects of the strong electric field of the FRB wave (strength parameter $a \gg 1$) on the upstream medium. One-dimensional particle-in-cell simulations of magnetized shocks into a pair plasma are presented which demonstrate that high maser efficiency can be preserved, even in the limit $a \gg 1$ in which the FRB wave accelerates the upstream electrons to ultra-relativistic speeds.
- [13] arXiv:1911.05772 [pdf, other]
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Title: ADMX SLIC: Results from a Superconducting LC Circuit Investigating Cold AxionsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
Axions are a promising cold dark matter candidate. Haloscopes, which use the conversion of axions to photons in the presence of a magnetic field to detect axions, are the basis of microwave cavity searches such as the Axion Dark Matter eXperiment (ADMX). To search for lighter, low frequency axions in the sub $2\times10^{-7}$ eV (50 MHz) range, a tunable lumped-element LC circuit has been proposed. For the first time, through ADMX SLIC (Superconducting Lc circuit Investigating Cold axions), a resonant LC circuit was used to probe this region of axion mass-coupling space. The detector used a superconducting LC circuit with piezoelectric driven capacitive tuning. The axion mass and corresponding frequency range $1.7498 -1.7519 \times10^{-7}$ eV (42.31 -- 42.36 MHz), $1.7734 - 1.7738 \times10^{-7}$ eV (42.88 -- 42.89 MHz), and $1.8007 - 1.8015 \times10^{-7}$ eV (43.54 -- 43.56 MHz) was covered at magnetic fields of 4.5 T, 5.0 T, and 7.0 T respectively. Exclusion results from the search data, for coupling below $10^{-12} \text{GeV}^{-1}$ are presented.
- [14] arXiv:1911.05790 [pdf, other]
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Title: Evolving LMXBs: CARB Magnetic BrakingComments: 7 pages, 3 figures, 1 table. Accepted to ApjLSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
The formation of low-mass X-ray binaries (LMXBs) is an ongoing challenge in stellar evolution. The important subset of LMXBs are the binary systems with a neutron star (NS) accretor. In NS LMXBs with non-degenerate donors, the mass transfer is mainly driven by magnetic braking. The discrepancies between the observed mass transfer (MT) rates and the theoretical models were known for a while. Theory predictions of the MT rates are too weak and differ by an order of magnitude or more. Recently, we showed that with the standard magnetic braking, it is not possible to find progenitor binary systems such that they could reproduce -- at any time of their evolution -- most of the observed persistent NS LMXBs. In this ${\it Letter}$ we present a modified magnetic braking prescription, CARB (Convection And Rotation Boosted). CARB magnetic braking combines two recent improvements in understanding stellar magnetic fields and magnetized winds -- the dependence of the magnetic field strength on the outer convective zone and the dependence of the Alfv\`en radius on the donor's rotation. Using this new magnetic braking prescription, we can reproduce the observed mass transfer rates at the detected mass ratio and orbital period for all well-observed to-the-date Galactic persistent NS LMXBs. For the systems where the effective temperature of the donor stars is known, theory agrees with observations as well.
- [15] arXiv:1911.05791 [pdf, other]
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Title: The Assembly of the First Massive Black HolesComments: Invited review in Annual Reviews of Astronomy & Astrophysics; an edited final version is to appear in volume 58, to be published in 2020Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The existence of $\approx$10^9 Msun supermassive black holes (SMBHs) within the first billion year of the universe has stimulated numerous ideas for the prompt formation and rapid growth of BHs in the early universe. Here we review ways in which the seeds of massive BHs may have first assembled, how they may have subsequently grown as massive as $\approx$10^9 Msun, and how multi-messenger observations could distinguish between different SMBH assembly scenarios. We conclude the following: (1) The ultra-rare $\approx$10^9 Msun SMBHs represent only the tip of the iceberg. Early BHs likely fill a continuum from stellar-mass (approx. 10 Msun) to the super-massive ($\approx$10^9 Msun) regime, reflecting a range of initial masses and growth histories. (2) Stellar-mass BHs were likely left behind by the first generation of stars at redshifts as high as z=30, but their initial growth was typically stunted due to the shallow potential wells of their host galaxies. (3) Conditions in some larger, metal-poor galaxies soon became conducive to the rapid formation and growth of massive `seed' holes, via gas accretion and by mergers in dense stellar clusters. (4) BH masses depend on the environment (such as the number and properties of nearby radiation sources and the local baryonic streaming velocity), and on the metal enrichment and assembly history of the host galaxy. (5) Distinguishing between assembly mechanisms will be difficult, but a combination of observations by LISA (probing massive BH growth via mergers) and by deep multi-wavelength electromagnetic observations (probing growth via gas accretion) is particularly promising.
- [16] arXiv:1911.05792 [pdf, ps, other]
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Title: On the Expansion, Age, and Origin of the Puzzling Shell/Pulsar Wind Nebula G310.6-1.6Comments: 11 pages, 10 figures; accepted for publication in the Astrophysical JournalSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present a 142-ks Chandra observation of the enigmatic combination supernova remnant G310.6-1.6 consisting of a bright pulsar-wind nebula driven by an energetic pulsar, surrounded by a highly circular, very faint shell with a featureless, probably synchrotron, spectrum. Comparison with an observation 6 years earlier shows no measurable expansion of the shell, though some features in the pulsar-wind nebula have moved. We find an expansion age of at least 2500 yr, implying a current shock velocity less than about 1000 km/s. We place severe upper limits on thermal emission from the shell; if the shell locates the blast wave, a Sedov interpretation would require the remnant to be very young, about 1000 yr, and to have resulted from a dramatically sub-energetic supernova, ejecting << 0.02 M_sun with energy E < 3 x 10^47 erg. Even a merger-induced collapse of a white dwarf to a neutron star, with a low-energy explosion, is unlikely to produce such an event. Other explanations seem equally unlikely.
- [17] arXiv:1911.05796 [pdf, ps, other]
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Title: Response to NITRD, NCO, NSF Request for Information on "Update to the 2016 National Artificial Intelligence Research and Development Strategic Plan"Authors: J. Amundson, J. Annis, C. Avestruz, D. Bowring, J. Caldeira, G. Cerati, C. Chang, S. Dodelson, D. Elvira, A. Farahi, K. Genser, L. Gray, O. Gutsche, P. Harris, J. Kinney, J. B. Kowalkowski, R. Kutschke, S. Mrenna, B. Nord, A. Para, K. Pedro, G. N. Perdue, A. Scheinker, P. Spentzouris, J. St. John, N. Tran, S. Trivedi, L. Trouille, W. L. K. Wu, C. R. BomSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Artificial Intelligence (cs.AI); Physics and Society (physics.soc-ph)
We present a response to the 2018 Request for Information (RFI) from the NITRD, NCO, NSF regarding the "Update to the 2016 National Artificial Intelligence Research and Development Strategic Plan." Through this document, we provide a response to the question of whether and how the National Artificial Intelligence Research and Development Strategic Plan (NAIRDSP) should be updated from the perspective of Fermilab, America's premier national laboratory for High Energy Physics (HEP). We believe the NAIRDSP should be extended in light of the rapid pace of development and innovation in the field of Artificial Intelligence (AI) since 2016, and present our recommendations below. AI has profoundly impacted many areas of human life, promising to dramatically reshape society --- e.g., economy, education, science --- in the coming years. We are still early in this process. It is critical to invest now in this technology to ensure it is safe and deployed ethically. Science and society both have a strong need for accuracy, efficiency, transparency, and accountability in algorithms, making investments in scientific AI particularly valuable. Thus far the US has been a leader in AI technologies, and we believe as a national Laboratory it is crucial to help maintain and extend this leadership. Moreover, investments in AI will be important for maintaining US leadership in the physical sciences.
- [18] arXiv:1911.05805 [pdf, other]
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Title: A Dissection of Spatially Resolved AGN Feedback across the Electromagnetic SpectrumAuthors: Travis Fischer, Krista Lynne Smith, Steve Kraemer, Henrique Schmitt, D. Michael Crenshaw, Michael Koss, Richard Mushotzky, Kirsten Larson, Vivian U, Jane RigbyComments: Accepted for publication in ApJ. 20 pages, 20 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present optical SuperNova Integral Field Spectrograph (SNIFS) integral field spectroscopy, Hubble Space Telescope optical imaging, Chandra X-ray imaging, and Very Large Array radio interferometry of the merging galaxy 2MASX J04234080+0408017, which hosts a Seyfert 2 active galactic nucleus (AGN) at z = 0.046. Our observations reveal that radiatively driven, ionized gas outflows are successful to distances > 10 kpc due to the low mass of the host system, encompassing the entirety of the observed optical emission. We also find that at large radii, where observed velocities cannot be reproduced by radiative driving models, high velocity kinematics are likely due to mechanical driving from AGN winds impacting high density host material. This impacting deposits sufficient energy to shock the host material, producing thermal X-ray emission and cosmic rays, which in turn promote the formation of in situ radio structure in a pseudo-jet morphology along the high density lanes.
- [19] arXiv:1911.05813 [pdf, other]
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Title: NuSTAR Uncovers an Extremely Local Compton-thick AGN in NGC 4968Authors: Stephanie M. LaMassa, Tahir Yaqoob, Peter G. Boorman, Panayiotis Tzanavaris, N. A. Levenson, Poshak Gandhi, Andrew F. Ptak, Timothy M. HeckmanComments: accepted for publication in ApJ; 20 pages, 8 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present the analysis of Chandra and NuSTAR spectra of NGC 4968, a local (D$\sim$44 Mpc) 12$\mu$m-selected Seyfert 2 galaxy, enshrouded within Compton-thick layers of obscuring gas. We find no evidence of variability between the Chandra and NuSTAR observations (separated by 2 years), and between the two NuSTAR observations (separated by 10 months). Using self-consistent X-ray models, we rule out the scenario where the obscuring medium is nearly spherical and uniform, contradicting the results implied by the $<$10 keV Chandra spectrum. The line-of-sight column density, from intervening matter between the source and observer that intercepts the intrinsic AGN X-ray emission, is well within the Compton-thick regime, with a minimum column density of $2\times10^{24}$ cm$^{-2}$. The average global column density is high ($> 3\times10^{23}$ cm$^{-2}$), with both Compton-thick and Compton-thin solutions permitted depending on the X-ray spectral model. The spectral models provide a range of intrinsic AGN continuum parameters and implied 2-10 keV luminosities ($L_{\rm 2-10keV,intrinsic}$), where the higher end of $L_{\rm 2-10keV,intrinsic}$ is consistent with expectations from the 12$\mu$m luminosity ($L_{\rm 2-10keV,intrinisc} \sim 7\times10^{42}$ erg s$^{-1}$). Compared with Compton-thick AGN previously observed by {\it NuSTAR}, NGC 4968 is among the most intrinsically X-ray luminous. However, despite its close proximity and relatively high intrinsic X-ray luminosity, it is undetected by the 105 month Swift-BAT survey, underscoring the importance of multi-wavelength selection for obtaining the most complete census of the most hidden black holes.
- [20] arXiv:1911.05820 [pdf, other]
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Title: The Broadband X-ray Spectrum of the X-ray Obscured Type 1 AGN 2MASX J193013.80+341049.5Authors: Nikita Kamraj, Mislav Baloković, Murray Brightman, Daniel Stern, Fiona A. Harrison, Roberto J. Assef, Michael J. Koss, Kyuseok Oh, Dominic J. WaltonComments: 13 pages, 9 figures. Accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present results from modeling the broadband X-ray spectrum of the Type 1 AGN 2MASX J193013.80+341049.5 using NuSTAR, Swift and archival XMM-Newton observations. We find this source to be highly X-ray obscured, with column densities exceeding 10$^{23}$ cm$^{-2}$ across all epochs of X-ray observations, spanning an 8 year period. However, the source exhibits prominent broad optical emission lines, consistent with an unobscured Type 1 AGN classification. We fit the X-ray spectra with both phenomenological reflection models and physically-motivated torus models to model the X-ray absorption. We examine the spectral energy distribution of this source and investigate some possible scenarios to explain the mismatch between X-ray and optical classifications. We compare the ratio of reddening to X-ray absorbing column density ($E_{B-V}/N_{H}$) and find that 2MASX J193013.80+341049.5 likely has a much lower dust-to-gas ratio relative to the Galactic ISM, suggesting that the Broad Line Region (BLR) itself could provide the source of extra X-ray obscuration, being composed of low-ionization, dust-free gas.
- [21] arXiv:1911.05821 [pdf, other]
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Title: Variable Star Classification Using Multi-View Metric LearningComments: 16 pages, 11 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Our multi-view metric learning framework enables robust characterization of star categories by directly learning to discriminate in a multi-faceted feature space, thus, eliminating the need to combine feature representations prior to fitting the machine learning model. We also demonstrate how to extend standard multi-view learning, which employs multiple vectorized views, to the matrix-variate case which allows very novel variable star signature representations. The performance of our proposed methods is evaluated on the UCR Starlight and LINEAR datasets. Both the vector and matrix-variate versions of our multi-view learning framework perform favorably --- demonstrating the ability to discriminate variable star categories.
- [22] arXiv:1911.05830 [pdf, other]
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Title: Investigating the Planet-Metallicity Correlation for Hot JupitersComments: 8 pages, 4 figures, accepted for publication in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
We investigate the giant planet-metallicity correlation for a homogeneous, unbiased set of 217 hot Jupiters taken from nearly 15 years of wide-field ground-based surveys. We compare the host star metallicity to that of field stars using the Besan\c{c}on Galaxy model, allowing for a metallicity measurement offset between the two sets. We find that hot Jupiters preferentially orbit metal rich stars. However, we find the correlation consistent, though marginally weaker, for hot Jupiters ($\beta=0.71^{+0.56}_{-0.34}$) than it is for other longer period gas giant planets from radial velocity surveys. This suggests that the population of hot Jupiters probably formed in a similar process to other gas giant planets, and differ only in their migration histories.
- [23] arXiv:1911.05836 [pdf, other]
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Title: The Dark Matter Distributions in Low-Mass Disk Galaxies. II. The Inner Density ProfilesAuthors: Nicole C. Relatores, Andrew B. Newman, Joshua D. Simon, Richard S. Ellis, Phuongmai Truong, Leo Blitz, Alberto Bolatto, Christopher Martin, Matt Matuszewski, Patrick Morrissey, James D. NeillSubjects: Astrophysics of Galaxies (astro-ph.GA)
Dark matter-only simulations predict that dark matter halos have steep, cuspy inner density profiles, while observations of dwarf galaxies find a range of inner slopes that are often much shallower. There is debate whether this discrepancy can be explained by baryonic feedback or if it may require modified dark matter models. In Paper 1 of this series, we obtained high-resolution integral field H$\alpha$ observations for 26 dwarf galaxies with $M_*=10^{8.1}-10^{9.7}\textrm{M}_\odot$. We derived rotation curves from our observations, which we use here to construct mass models. We model the total mass distribution as the sum of a generalized Navarro-Frenk-White (NFW) dark matter halo and the stellar and gaseous components. Our analysis of the slope of the dark matter density profile focuses on the inner 300-800 pc, chosen based on the resolution of our data and the region resolved by modern hydrodynamical simulations. The inner slope measured using ionized and molecular gas tracers is consistent, and it is additionally robust to the choice of stellar mass-to-light ratio. We find a range of dark matter profiles, including both cored and cuspy slopes, with an average of $\rho_{\rm DM}\sim r^{-0.74\pm 0.07}$, shallower than the NFW profile, but steeper than those typically observed for lower-mass galaxies with $M_*\sim 10^{7.5}\textrm{M}_\odot$. Simulations that reproduce the observed slopes in those lower-mass galaxies also produce slopes that are too shallow for galaxies in our mass range. We therefore conclude that supernova feedback models do not yet provide a fully satisfactory explanation for the observed trend in dark matter slopes.
- [24] arXiv:1911.05838 [pdf, other]
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Title: A Map Between Primordial Power Spectra and the Effective Field Theory of InflationAuthors: Amel DurakovicComments: 9 pages, 6 figures; to appear in the proceedings of the 15th Rencontres du Vietnam conference on cosmology that took place at ICISE, Quy Nhon, 11-17 August 2019Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
We have developed a precise dictionary between the spectrum of primordial density fluctuations and the parameters of the effective field theory (EFT) of inflation that determine the primordial power spectrum (PPS). At lowest order the EFT contains two parameters: the slow-roll parameter $\epsilon$, which acts as an order parameter, and the speed of sound $c_s$. Applying second-order perturbation theory, we provide maps from the PPS to the EFT parameters that are precise up to the cube of the fractional change in the PPS $(\Delta \mathcal{P}/\mathcal{P})^3$, or less than $1\%$ for spectral features that modulate the PPS by $20\%$. While such features are not required when the underlying cosmological model is assumed to be $\Lambda$CDM they are necessary for alternative models that have no cosmological constant/dark energy. We verify the dictionary numerically and find those excursions in the slow-roll parameter that reproduce the PPS needed to fit Planck data for both $\Lambda$ and no-$\Lambda$ cosmological models.
- [25] arXiv:1911.05841 [pdf, other]
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Title: Observation of Eclipse Shadow Bands Using High Altitude Balloon and Ground-Based Photodiode ArraysAuthors: Janvi P. Madhani, Grace E. Chu, Carlos Vazquez Gomez, Sinjon Bartel, Russell J. Clark, Lou W. Coban, Marshall Hartman, Edward M. Potosky, Sandhya M. Rao, David A. TurnshekComments: 11 pages, 8 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
The results of an investigation into whether or not eclipse shadow bands have an atmospheric origin are presented. Using high altitude balloon and ground-based photodiode arrays during the 21 August 2017 total solar eclipse, data revealing the light patterns before and after totality were collected. These data were then analyzed using spectrograms. Both at the altitude of the balloon and on the ground, a sustained ~ 4.5 Hz signal was detected a few minutes before and after totality. This signal was coherent over a scale greater than 10 cm and detected in four separate balloon photodiodes and 16 ground photodiodes. At higher frequencies, up to at least 30 Hz, brief chaotic signals that were disorganized as a function of time were detected on the ground, but not at the altitude of the balloon and appeared mostly uncorrelated over a length scale of 10 cm. Some of our ground arrays utilized red and blue filters, but neither the sustained 4.5 Hz signal nor the higher frequency signals showed a strong dependence on filter color. On the ground we made a video of the shadow bands on a scaled white screen. We judged that the bands were roughly parallel to the orientation of the bright thin crescent Sun before and after totality and inferred that their propagation velocity was about v ~ 59 cm /s. Shadow band signals other than the sustained signal at ~ 4.5 Hz are consistent with atmospheric scintillation theory.
These results are surprising. Based on accounts in the literature we expected to confirm the atmospheric scintillation theory of eclipse shadow bands, but instead we detected a sustained ~ 4.5 Hz signal at both high altitude and on the ground. This signal cannot be due to atmospheric scintillation and we ran a check to make sure this signal is not an artifact of our electronics. We recommend that additional searches for eclipse shadow bands be made at high altitude in the future. - [26] arXiv:1911.05872 [pdf]
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Title: Flat Field ForensicsComments: Scientific Detector Workshop 2017Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present two subtle charge transport problems revealed by the statistics of flat fields. Mark Downing has presented photon transfer curves showing variance dips of order 25% at signal levels around 80% of blooming. These dips appear when substrate voltage is raised above zero, for - 0V to 8V parallel clock swing. We present a modified parallel transfer sequence that eliminates the dip, based on the hypothesis that it is caused by charge spillage from last line to the 2nd last line. We discuss an experiment to test whether the electrode map is incorrectly reported in the data sheet. A more subtle dip in the variance occurs at signals around 6000 e-. This is eliminated by increasing serial clock high by a few volts, suggesting the existence of a small structural trap at the parallel-serial interface. Tails above blooming stars are suppressed using an inverted clocking during readout and a positive clocking during exposure to maintain sharpness of the PTC. We show that integrating under three parallel phases, instead of the two recommended, reduces pixel area variations from 0.39% to 0.28%, while also eliminating striations observed along central columns in pixel area maps. We show that systematic line and column width errors at stitching boundaries (~15 nm) are now an order of magnitude less than the random pixel area variations.
- [27] arXiv:1911.05877 [pdf, other]
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Title: The Giant Herbig-Haro Flow HH 212 and Associated Star FormationAuthors: Bo Reipurth, C.J. Davis, John Bally, A.C. Raga, B.P. Bowler, T.R. Geballe, Colin Aspin, Hsin-Fang ChiangComments: 17 pages, 10 figures, 2 tablesJournal-ref: Astron. J. 158:107, 2019Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
The bipolar jet HH 212, among the finest collimated jets known, has so far been detected only in near-infrared H$_2$ emission. Here we present deep optical images that show two of the major bow shocks weakly detected in optical [SII] emission, as expected for a bona fide Herbig-Haro jet. We present widefield H$_2$ images which reveal two more bow shocks located symmetrically around the source and along the main jet axis. Additionally, examination of Spitzer 4.5 $\mu$m images reveals yet another bright bow shock further to the north along the jet axis; no corresponding bow shock is seen to the south. In total, the HH 212 flow has an extent of 1050 arcsec, corresponding to a projected dimension of 2.0 pc. HH 212 thus joins the growing group of parsec-scale Herbig-Haro jets. Proper motion measurements indicate a velocity of about 170 km/sec, highly symmetric around the source, with an uncertainty of $\sim$30 km/sec, suggesting a probable age of the giant HH 212 flow of about 7000 yr. The jet is driven by a deeply embedded source, known as IRAS 05413-0104. We draw attention to a Spitzer near- and mid-infrared source, which we call IRS-B, located only 7 arcsec from the driving source, towards the outskirts of the dense cloud core. Infrared photometry and spectroscopy suggests that IRS-B is a K-type star with a substantial infrared excess, except that for an extinction of A$_V$ = 44 the star would have only a weakinfrared excess, and so in principle it could be a K-giant at a distance of about 2 kpc.
- [28] arXiv:1911.05882 [pdf, other]
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Title: The Most Massive Binary Black Hole Detections and the Identification of Population OutliersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Advanced LIGO and Virgo detected ten binary black holes (BBHs) in their first two observing runs (O1 and O2). Analysis of these events found strong evidence for a dearth of BBHs with component masses greater than $\sim45 \ M_\odot$, as would be expected from a pair-instability mass gap. Meanwhile, a standalone analysis of the merger GW170729 found its primary mass $m_1 = {51.2^{+16.2}_{-11.0} \ M_\odot}$, with the majority of its posterior support at $m_1 > 45 \ M_\odot$. Although this appears to be in contradiction with the existence of a limit at $\sim45\ M_\odot$, we argue that individual events cannot be evaluated without reference to the entire population. When GW170729 is analyzed jointly with the rest of the detections, as part of a full hierarchical population analysis, its inferred primary mass tightens considerably, to $m_1 = {38.9^{+7.3}_{-4.5} \ M_\odot}$. For a large sample of events in the presence of noise, apparent outliers in the detected distribution are inevitable, even if the underlying population forbids outliers. We discuss methods of distinguishing between statistical fluctuations and population outliers using posterior predictive tests. Applying these tests to the primary mass distribution in O1 and O2, we find that the ten detections are consistent with even the simplest power-law plus maximum-mass model considered by the LVC. This supports the claim that GW170729 is not a population outlier. We also provide non-parametric constraints on the rate of high-mass mergers and conservatively bound the rate of mergers with $m_1 > 45 \ M_\odot$ at $2.8^{+5.4}_{-2.0}\%$ of the total merger rate. After 100 detections like those of O1 and O2 from a population with a maximum primary mass of $45 \, M_\odot$, it would be common for the most massive system to have an observed maximum-likelihood mass $m_1 \gtrsim 70 \, M_\odot$.
- [29] arXiv:1911.05897 [pdf]
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Title: Spectral Structures of Type II Solar Radio Bursts and Solar Energetic ParticlesComments: 24 pages, 6 figures, accepted for publication in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
We investigated the relationship between the spectral structures of type II solar radio bursts in the hectometric and kilometric wavelength ranges and solar energetic particles (SEPs). To examine the statistical relationship between type II bursts and SEPs, we selected 26 coronal mass ejection (CME) events with similar characteristics (e.g., initial speed, angular width, and location) observed by the Large Angle and Spectrometric Coronagraph (LASCO), regardless of the characteristics of the corresponding type II bursts and the SEP flux. Then, we compared associated type II bursts observed by the Radio and Plasma Wave Experiment (WAVES) onboard the Wind spacecraft and the SEP flux observed by the Geostationary Operational Environmental Satellite (GOES) orbiting around the Earth. We found that the bandwidth of the hectometric type II bursts and the peak flux of the SEPs has a positive correlation (with a correlation coefficient of 0.64). This result supports the idea that the nonthermal electrons of type II bursts and the nonthermal ions of SEPs are generated by the same shock and suggests that more SEPs may be generated for a wider or stronger CME shock with a longer duration. Our result also suggests that considering the spectral structures of type II bursts can improve the forecasting accuracy for the peak flux of gradual SEPs.
- [30] arXiv:1911.05901 [pdf, other]
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Title: The Chemical Evolution of Iron-Peak Elements with HypernovaeComments: 17 pages, 14 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
We calculate the mean evolution of the iron-peak abundance ratios [(Cr,Mn,Co,Zn)/Fe] in the Galaxy, using modern supernova and hypernova chemical yields and a Galactic Chemical Evolution code that assumes homogeneous chemical evolution. We investigate a range of hypernova occurrence rates and are able to produce a chemical composition that is a reasonable fit to the observed values in metal-poor stars. This requires a hypernova occurence rate that is large (50%) in the early Universe, decreasing throughout evolution to a value that is within present day observational constraints (>~ 1%). A large hypernova occurence rate is beneficial to matching the high [Zn/Fe] observed in the most metal-poor stars, although including hypernovae with progenitor mass >= 60 solar masses is detrimental to matching the observed [(Mn,Co)/Fe] evolution at low [Fe/H]. A significant contribution from HNe seems to be critical for producing supersolar [(Co,Zn)/Fe] at low metallicity, though more work will need to be done in order to match the most extreme values. We also emphasise the need to update models for the enrichment sources at higher metallicity, as the satisfactory recovery of the solar values of [(Cr,Mn,Co,Zn)/Fe] still presents a challenge.
- [31] arXiv:1911.05902 [pdf, other]
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Title: Pre-discovery Activity of New Interstellar Comet 2I/Borisov Beyond 5 AUAuthors: Quanzhi Ye, Michael S. P. Kelley, Bryce T. Bolin, Dennis Bodewits, Davide Farnocchia, Frank J. Masci, Karen J. Meech, Marco Micheli, Robert Weryk, Eric C. Bellm, Eric Christensen, Richard Dekany, Alexandre Delacroix, Matthew J. Graham, Shrinivas R. Kulkarni, Russ R. Laher, Ben Rusholme, Roger M. SmithComments: AJ submittedSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Comet 2I/Borisov, the first unambiguous interstellar comet ever found, was discovered at $\sim3$ au from the Sun on its inbound leg. No pre-discovery detection beyond 3 au has yet been reported, mostly due to the comet's proximity to the Sun as seen from the Earth. Here we present a search for pre-discovery detections of comet Borisov using images taken by the Catalina Sky Survey (CSS), Pan-STARRS and Zwicky Transient Facility (ZTF), with a further comprehensive follow-up campaign being presented in Bolin et al. (2019). We identified comet Borisov in ZTF images taken in May 2019 and use these data to update its orbit. This allowed us to identify the comet in images acquired as far back as December 2018, when it was $\sim8$ au from the Sun. This suggests that the activity of the comet is driven by a more volatile species other than H$_2$O, such as CO or CO$_2$. The comet was not detected in November 2018 when it was 8.5 au from the Sun, possibly implying an onset of activity around this time. We derive the radius of the nucleus to be $<7$ km using the non-detection in November 2018, and estimate an area of $\sim0.5$---$10 \mathrm{km^2}$ has been active between December 2018 and September 2019, though this number is model-dependent and is highly uncertain. The behavior of comet Borisov during its inbound leg is observationally consistent with dynamically new comets observed in our solar system, suggesting some similarities between the two.
- [32] arXiv:1911.05925 [pdf, other]
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Title: THOR 42: A touchstone $\sim$24 Myr-old eclipsing binary spanning the fully-convective boundaryAuthors: Simon J. Murphy, Warrick A. Lawson, Christopher A. Onken, David Yong, Gary S. Da Costa, George Zhou, Eric E. Mamajek, Cameron P. M. Bell, Michael S. Bessell, Adina D. FeinsteinComments: Accepted for publication in MNRAS. 22 pages. Tables 4 and 5 are available in full as ancillary filesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
We present the characterization of CRTS J055255.7$-$004426 (=THOR 42), a young eclipsing binary comprising two pre-main sequence M dwarfs (combined spectral type M3.5). This nearby (103 pc), short-period (0.859 d) system was recently proposed as a member of the $\sim$24 Myr-old 32 Orionis Moving Group. Using ground- and space-based photometry in combination with medium- and high-resolution spectroscopy, we model the light and radial velocity curves to derive precise system parameters. The resulting component masses and radii are $0.497\pm0.005$ and $0.205\pm0.002$ $\rm{M}_{\odot}$, and $0.659\pm0.003$ and $0.424\pm0.002$ $\rm{R}_{\odot}$, respectively. With mass and radius uncertainties of $\sim$1 per cent and $\sim$0.5 per cent, respectively, THOR 42 is one of the most precisely characterized pre-main sequence eclipsing binaries known. Its systemic velocity, parallax, proper motion, colour-magnitude diagram placement and enlarged radii are all consistent with membership in the 32 Ori Group. The system provides a unique opportunity to test pre-main sequence evolutionary models at an age and mass range not well constrained by observation. From the radius and mass measurements we derive ages of 22-26 Myr using standard (non-magnetic) models, in excellent agreement with the age of the group. However, none of the models can simultaneously reproduce the observed mass, radius, temperature and luminosity of the coeval components. In particular, their H-R diagram ages are 2-4 times younger and we infer masses $\sim$50 per cent smaller than the dynamical values.
- [33] arXiv:1911.05929 [pdf, other]
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Title: Blinding multi-probe cosmological experimentsAuthors: J. Muir, G. M. Bernstein, D. Huterer, F. Elsner, E. Krause, A. Roodman, S. Allam, J. Annis, S. Avila, K. Bechtol, E. Bertin, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, R. Cawthon, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, J. P. Dietrich, P. Doel, T. F. Eifler, S. Everett, P. Fosalba, J. Frieman, J. García-Bellido, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, W. G. Hartley, D. L. Hollowood, D. J. James, M. Jarvis, K. Kuehn, N. Kuropatkin, O. Lahav, M. March, J. L. Marshall, P. Melchior, F. Menanteau, R. Miquel, R. L. C. Ogando, A. Palmese, F. Paz-Chinchón, A. A. Plazas, A. K. Romer, E. Sanchez, V. Scarpine, M. Schubnell, S. Serrano, I. Sevilla-Noarbe, M. Smith, E. Suchyta, G. Tarle, D. Thomas, M. A. Troxel, A. R. Walker, et al. (4 additional authors not shown)Comments: 18 pages, 13 figures, data available upon requestSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
The goal of blinding is to hide an experiment's critical results --- here the inferred cosmological parameters --- until all decisions affecting its analysis have been finalised. This is especially important in the current era of precision cosmology, when the results of any new experiment are closely scrutinised for consistency or tension with previous results. In analyses that combine multiple observational probes, like the combination of galaxy clustering and weak lensing in the Dark Energy Survey (DES), it is challenging to blind the results while retaining the ability to check for (in)consistency between different parts of the data. We propose a simple new blinding transformation that works by modifying the summary statistics that are input to parameter estimation, such as two-point correlation functions. The transformation shifts the measured statistics to new values that are consistent with (blindly) shifted cosmological parameters, while preserving internal (in)consistency. We apply the blinding transformation to simulated data for the projected DES Year 3 galaxy clustering and weak lensing analysis, demonstrating that practical blinding is achieved without significant perturbation of internal-consistency checks, as measured here by degradation of the $\chi^2$ between data and best-fitting model. Our blinding method conserves $\chi^2$ more precisely as experiments evolve to higher precision.
- [34] arXiv:1911.05948 [pdf, ps, other]
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Title: Evolution implications of neutron star magnetic fields: inferred from pulsars and cyclotron lines of HMXBsComments: 8 pages, 2 figures, 4 tables, accepted by Astrophysics and Space ScienceSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The evolution of neutron star (NS) magnetic field (B-field) has long been an important topic, which is still not yet settled down. Here, we analyze the NS B-fields inferred by the cyclotron resonance scattering features (CRSFs) for the high mass X-ray binaries (HMXBs) and by the magnetic dipole model for the spin-down pulsars. We find that the B-fields of both the 32 NSHMXBs and 28 young pulsars with the supernova remnants follow the log-normal distributions, with the average values of 3.4 * 10^12 G and 4.1 * 10^12 G respectively, which are further verified to come from the same continuous distribution by the statistical tests. These results declaim that the two methods of measuring NS B-fields are reliable for the above two groups of samples. In addition, since the NS-HMXBs have experienced the spin-down phase as the normal pulsars without accretion and then the spin-up phase by accretion, their ages should be about million years (Myrs). Our statistical facts imply that the B-fields of NS-HMXBs have little decayed in their non-accretion spin-down phases of ~ Myrs, as well as in their accretion phases of ~ 0.1Myrs.
- [35] arXiv:1911.05973 [pdf, other]
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Title: Testing kinetically coupled inflation models with CMB distortionsComments: 19 pages, 22 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Inflation scenarios kinetically coupled with the Einstein tensor have been widely studied. They can be consistent with current observational data. Future experiments on the measurement on CMB distortions will potentially extend information about the scalar spectrum to small scales $1 \Mpc^{-1} \lesssim k \lesssim 2 \times 10^4 \Mpc^{-1}$. By taking the sensitivity of the PIXIE experiment as criterion, we perform a model-oriented analysis of the observational prospects of spectral distortions for kinetically coupled inflation. There are five models that can generate a detectable level of distortions, among the 49 single-field inflation models listed in Ref. \cite{Martin2013a}. These models are: hybrid inflation in the valley (VHI), non-canonical K\"{a}hler inflation (NCKI), generalized MSSM inflation (GMSSMI), generalized renormalization point inflation (GRIPI), and running-mass inflation (RMI). Each of these models can induce $5 \sigma$ detectable signals in a tuned region of their parameter space. The existence of kinetic coupling suppresses the value of the model parameters with mass dimension for VHI, GMSSMI, and GRIPI, such that these three models can be in agreement with their theoretical considerations.
- [36] arXiv:1911.05976 [pdf, ps, other]
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Title: Modeling and analysis of medium-resolution integrated-light spectra of globular clusters in dwarf galaxiesComments: 4 pages, 3 figures, 1 table, to appear in the proceedings of the IAUS351 "Star Clusters: From the Milky Way to the Early Universe", A. Bragaglia, M.B. Davies, A. Sills & E. Vesperini, edsSubjects: Astrophysics of Galaxies (astro-ph.GA)
The study of ages, helium mass fraction (Y) and chemical composition of globular clusters in dwarf galaxies is important for understanding the physical conditions at the main evolutionary stages of the host galaxies and for constraining the build-up histories of large galaxies. We present the analysis of integrated-light spectra of 8 extragalactic and 20 Galactic globular clusters (GCs) using our population synthesis method. We calculate synthetic spectra of GCs according to the defined stellar mass functions using model atmospheres and stellar parameters ($[Fe/H]$, $T_{eff}$, and $log g$) set by theoretical isochrones. The main advantage of our method is the ability to determine not only chemical composition but also the age and mean Y in a cluster by modelling and analysis of Balmer absorption lines. The knowledge of Y and anomalies of light elements in star clusters is one of the key points for understanding the phenomenon of multiple stellar populations.
- [37] arXiv:1911.05989 [pdf]
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Title: Elephants, goldfishes and SOUL: a dissertation on forgetfulness and control systemsComments: AO4ELT6 proceedingsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Adaptive Optics control systems accumulate differential measurements during closed loop operations to estimate turbulence and drive the deformable mirror. But have you ever wondered if your control system should be like an elephant, and never forget, or should it have a weak memory like a goldfish? Are measurement errors always zero mean or does static effects impact performance? Are commands high spatial frequencies good or are you wasting all the inter-actuator stroke for nothing? This work will try to answer these questions showing you results obtained during SOUL commissioning and analysing the impact of the values of the control system poles on Adaptive Optics. So be prepared to focus on forgetfulness and discover the advantages of being a goldfish in a digital world made of elephants.
- [38] arXiv:1911.06005 [pdf, other]
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Title: Demographics of disks around young very low-mass stars and brown dwarfs in LupusAuthors: E. Sanchis, L. Testi, A. Natta, C. F. Manara, B. Ercolano, T. Preibisch, T. Henning, S. Facchini, A. Miotello, I. de Gregorio-Monsalvo, C. Lopez, K. Mužić, I. Pascucci, A Santamaría-Miranda, A. Scholz, M. Tazzari, S. van Terwisga, J. P. WilliamsComments: Accepted for publication on A&A, 14 pages of main text with 13 figures, and 9 pages of appendices A, B, C and D with 14 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
We present new 890 $\mu m$ continuum ALMA observations of 5 brown dwarfs (BDs) with infrared excess in Lupus I and III -- which, in combination with 4 BDs previously observed, allowed us to study the mm properties of the full known BD disk population of one star-forming region. Emission is detected in 5 out of the 9 BD disks. Dust disk mass, brightness profiles and characteristic sizes of the BD population are inferred from continuum flux and modeling of the observations. Only one source is marginally resolved, allowing for the determination of its disk characteristic size. We conduct a demographic comparison between the properties of disks around BDs and stars in Lupus. Due to the small sample size, we cannot confirm or disprove if the disk mass over stellar mass ratio drops for BDs, as suggested for Ophiuchus. Nevertheless, we find that all detected BD disks have an estimated dust mass between 0.2 and 3.2 $M_{\bigoplus}$; these results suggest that the measured solid masses in BD disks can not explain the observed exoplanet population, analogous to earlier findings on disks around more massive stars. Combined with the low estimated accretion rates, and assuming that the mm-continuum emission is a reliable proxy for the total disk mass, we derive ratios of $\dot{M}_{\mathrm{acc}} / M_{\mathrm{disk}}$ significantly lower than in disks around more massive stars. If confirmed with more accurate measurements of disk gas masses, this result could imply a qualitatively different relationship between disk masses and inward gas transport in BD disks.
- [39] arXiv:1911.06011 [pdf, other]
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Title: Ultrahigh-energy cosmic ray interactions as the origin of very high energy $γ-$rays from BL LacsComments: 15 pages, 6 figures, 2 tablesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We explain the observed multiwavelength photon spectrum of a number of BL Lac objects detected at very high energy (VHE, $E \gtrsim 30$ GeV), using a lepto-hadronic emission model. The one-zone leptonic emission is employed to fit the synchrotron peak. Subsequently, the SSC spectrum is calculated, such that it extends up to the highest energy possible for the jet parameters considered. The data points beyond this energy, and also in the entire VHE range are well explained using a hadronic emission model. The ultrahigh-energy cosmic rays (UHECRs, $E\gtrsim 0.1$ EeV) escaping from the source interact with the extragalactic background light (EBL) during propagation over cosmological distances to initiate electromagnetic cascade down to $\sim1$ GeV energies. The resulting photon spectrum peaks at $\sim1$ TeV energies. We consider a random turbulent extragalactic magnetic field (EGMF) with a Kolmogorov power spectrum to find the survival rate of UHECRs within 0.1 degrees of the direction of propagation in which the observer is situated. We restrict ourselves to an RMS value of EGMF, $B_{\rm rms}\sim 10^{-5}$ nG, for a significant contribution to the photon spectral energy distribution (SED) from UHECR interactions. We found that UHECR interactions on the EBL and secondary cascade emission can fit gamma-ray data from the BL Lacs we considered at the highest energies. The required luminosity in UHECRs and corresponding jet power are below the Eddington luminosities of the super-massive black holes in these BL Lacs.
- [40] arXiv:1911.06024 [pdf, other]
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Title: Improved gravitational radiation time-scales: significance for LISA and LIGO-Virgo sourcesComments: Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
We compute a revised version of Peters' (1964) time-scale for the gravitational-wave (GW) induced decay of two point masses, by taking into account post-Newtonian (PN) perturbations of the orbital motion. At first PN order, the corrected time-scale can be approximated by multiplying Peters' estimate by the simple factor $Q = 1 + 5 (r_{\rm S}/p)$, where $p$ is the periapsis and $r_{\rm S}$ the Schwarzschild radius of the system. We apply the revised time-scale to a set of typical LIGO-Virgo and LISA sources at the onset of their GW driven decay. We argue that our more accurate model for the orbital evolution will affect current event and detection rate estimates for mergers of compact object binaries, with stronger deviations for LISA sources (EMRIs, IMRIs, and SMBH binaries). We propose the correction factor $Q$ as a simple analytical prescription to quantify decay time-scales more accurately in future population synthesis models.
- [41] arXiv:1911.06029 [pdf, other]
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Title: Optical intensity interferometry observations using the MAGIC imaging atmospheric Cherenkov telescopesAuthors: V. A. Acciari, M. I. Bernardos, E. Colombo, J. L. Contreras, J. Cortina, C. Delgado, C. Diaz, D. Fink, M. Mariotti, S. Mangano, R. Mirzoyan, M. Polo, T. Schweizer, M. WillComments: 9 pages, 6 figures, 4 tables, accepted for publication in MNRASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Imaging Atmospheric Cherenkov Telescopes (IACTs) currently in operation feature large mirrors and order of 1 ns time response to signals of a few photo-electrons produced by optical photons. This means that they are ideally suited for optical interferometry observations. Thanks to their sensitivity to visible wavelengths and long baselines optical intensity interferometry with IACTs allows reaching angular resolutions of tens to microarcsec. We have installed a simple optical setup on top of the cameras of the two 17 m diameter MAGIC IACTs and observed coherent fluctuations in the photon intensity measured at the two telescopes for three different stars. The sensitivity is roughly 10 times better than that achieved in the 1970s with the Narrabri interferometer.
- [42] arXiv:1911.06033 [pdf, other]
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Title: Particle Telescope aboard FORESAIL-1: simulated performanceAuthors: Philipp Oleynik (1), Rami Vainio (1), Hannu-Pekka Hedman (2), Arttu Punkkinen (1), Risto Punkkinen (2), Lassi Salomaa (2), Tero Säntti (2), Jarno Tuominen (2,3) Pasi Virtanen (1), Alexandre Bosser (4), Pekka Janhunen (5), Emilia Kilpua (6), Minna Palmroth (5,6), Jaan Praks (4), Andris Slavinskis (4), Syed R. U. Kakakhel (2), Juhani Peltonen (1), Juha Plosila (2), Jani Tammi (2), Hannu Tenhunen (2), Tomi Westerlund (2) ((1) Department of Physics and Astronomy of the University of Turku, (2) Department of Future Technologies of the University of Turku, (3) Turku University of Applied Sciences, (4) School of Electrical Engineering of Aalto University, (5) Finnish Meteorological Institute, (6) Department of Physics of University of Helsinki)Comments: 28 pages, 12 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The Particle Telescope (PATE) of FORESAIL-1 mission is described. FORESAIL-1 is a CubeSat mission to polar Low Earth Orbit. Its scientific objectives are to characterize electron precipitation from the radiation belts and to observe energetic neutral atoms (ENAs) originating from the Sun during the strongest solar flares. For that purpose, the 3-unit CubeSat carries a particle telescope that measures energetic electrons in the nominal energy range of 80--800 keV in seven energy channels and energetic protons at 0.3--10 MeV in ten channels. In addition, particles penetrating the whole telescope at higher energies will be measured in three channels: one $>$800 keV electron channel, two integral proton channels at $>$10 MeV energies. The instrument contains two telescopes at right angles to each other, one measuring along the spin axis of the spacecraft and one perpendicular to it. During a spin period (nominally 15 s), the rotating telescope will, thus, deliver angular distributions of protons and electrons, at 11.25-degree clock-angle resolution, which enables one to accurately determine the pitch-angle distribution and separate the trapped and precipitating particles. During the last part of the mission, the rotation axis will be accurately pointed toward the Sun, enabling the measurement of the energetic hydrogen from that direction. Using the geomagnetic field as a filter and comparing the rates observed by the two telescopes, the instrument can observe the solar ENA flux for events similar to the only one so far observed in December 2006. We present the Geant4-simulated energy and angular response functions of the telescope and assess its sensitivity showing that they are adequate to address the scientific objectives of the mission.
- [43] arXiv:1911.06046 [pdf, ps, other]
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Title: Modified Cosmology Models from Thermodynamical ApproachComments: 17 pages, 12 figures, accepted for publication in EPJCSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
We apply the first law of thermodynamics to the apparent horizon of the universe with the power-law corrected and non-extensive Tsallis entropies rather than the Bekenstein-Hawking one. We examine the cosmological properties in the two entropy models by using the CosmoMC package. In particular, the first numerical study for the cosmological observables with the power-law corrected entropy is performed. We also show that the neutrino mass sum has a non-zero central value with a relaxed upper bound in the Tsallis entropy model comparing with that in the $\Lambda$CDM one.
- [44] arXiv:1911.06070 [pdf, other]
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Title: The MUSE Atlas of Disks (MAD): Ionized gas kinematic maps and an application to Diffuse Ionized GasAuthors: Mark den Brok, C. Marcella Carollo, Santiago Erroz-Ferrer, Martina Fagioli, Jarle Brinchmann, Eric Emsellem, Davor Krajnović, Raffaella A. Marino, Masato Onodera, Sandro Tacchella, Peter M. Weilbacher, Joanna WooComments: 22 pages, accepted by MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We have obtained data for 41 star forming galaxies in the MUSE Atlas of Disks (MAD) survey with VLT/MUSE. These data allow us, at high resolution of a few 100 pc, to extract ionized gas kinematics ($V, \sigma$) of the centers of nearby star forming galaxies spanning 3 dex in stellar mass. This paper outlines the methodology for measuring the ionized gas kinematics, which we will use in subsequent papers of this survey. We also show how the maps can be used to study the kinematics of diffuse ionized gas for galaxies of various inclinations and masses. Using two different methods to identify the diffuse ionized gas, we measure rotation velocities of this gas for a subsample of 6 galaxies. We find that the diffuse ionized gas rotates on average slower than the star forming gas with lags of 0-10 km/s while also having higher velocity dispersion. The magnitude of these lags is on average 5 km/s lower than observed velocity lags between ionized and molecular gas. Using Jeans models to interpret the lags in rotation velocity and the increase in velocity dispersion we show that most of the diffuse ionized gas kinematics are consistent with its emission originating from a somewhat thicker layer than the star forming gas, with a scale height that is lower than that of the stellar disk.
- [45] arXiv:1911.06082 [pdf, other]
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Title: Signatures of Dark Matter in Cosmic-Ray ObservationsAuthors: Alessandro CuocoComments: 8 pages, 2 figures, contribution to the proceedings of the 16th TAUP conference, Sept. 9-13 2019, Toyama, JapanSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
I provide a short review of the current status of indirect dark matter searches with gamma rays, charged cosmic rays and neutrinos. For each case I will focus on various excesses reported in the literature which have been interpreted as possible hints of dark matter, and I will use them as examples to discuss theoretical aspects and analysis methodologies.
- [46] arXiv:1911.06097 [pdf, other]
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Title: Multi-messenger astronomy with very-high-energy gamma-ray observationsComments: Proceedings of TAUP2019Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
After decades of development, multi-messenger astronomy, the combination of information on cosmic sources from photons, neutrinos, charged particles and gravitational waves, is now an established reality. Within this emerging discipline we argue that very-high-energy (VHE) gamma-ray observations play a special role. We discuss the recent progress on explosive transients, the connections between neutrino and gamma-ray astronomy and the search for search for dark matter. Finally, the experimental prospects for the next decade in the VHE gamma-ray field are summarised.
- [47] arXiv:1911.06101 [pdf, other]
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Title: NELIOTA: Methods, statistics and results for meteoroids impacting the MoonAuthors: Alexios Liakos, Alceste Bonanos, Emmanouil Xilouris, Detlef Koschny, Ioannis Bellas-Velidis, Panayotis Boumis, Vassilios Charmandaris, Anastasios Dapergolas, Anastasios Fytsilis, Athanassios Maroussis, Richard MoisslComments: 31 pages, submitted for publication in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
This paper contains the results from the first 30 months of the NELIOTA project for impacts of NEOs/meteoroids on the lunar surface. Our analysis on the statistics concerning the efficiency of the campaign and the parameters of the projectiles and the impacts is presented. The parameters of the lunar impact flashes based on simultaneous observations in two wavelength bands are used to estimate the distributions of the masses, sizes and frequency of the impactors. These statistics can be used both in space engineering and science. The photometric fluxes of the flashes are measured using aperture photometry and their apparent magnitudes are calculated using standard stars. Assuming that the flashes follow a black body law of irradiation, the temperatures can be derived analytically, while the parameters of the projectiles are estimated using fair assumptions on their velocity and luminous efficiency of the impacts. 79 lunar impact flashes have been observed with the 1.2 m Kryoneri telescope in Greece. The masses of the meteoroids range between 0.7 g and 8 kg and their respective sizes between 1-20 cm depending on their assumed density, impact velocity, and luminous efficiency. We find a strong correlation between the observed magnitudes of the flashes and the masses of the meteoroids. Moreover, an empirical relation between the emitted energies of each band has been derived allowing the estimation of the physical parameters of the meteoroids that produce low energy impact flashes. The NELIOTA project has so far the highest detection rate and the faintest limiting magnitude for lunar impacts compared to other ongoing programs. Based on the impact frequency distribution on Moon, we estimate that sporadic meteoroids with typical masses less than 100 g and sizes less than 5 cm enter the mesosphere of the Earth with a rate ~108 meteoroids/hr and also impact Moon with a rate of ~8 meteoroids/hr.
- [48] arXiv:1911.06103 [pdf, other]
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Title: Complete census of massive slow rotators in ten large galaxy clustersComments: Submitted to Astronomy & Astrophysics on November 14th 2019Subjects: Astrophysics of Galaxies (astro-ph.GA)
Galaxy interactions leave imprints in the motions of their stars, and so observing the two-dimensional stellar kinematics allows us to uncover their formation process. Slow rotators, which have stellar orbits dominated by random motions, are thought to be the fossil relics of a sequence of multiple gas-poor mergers, in an environment where the cold gas required to form new stars is nearly absent. Indeed, observations of a handful of nearby galaxy clusters have indicated that slow rotators are preferentially found in the gas-poor, dense cores of clusters, which themselves must form by merging of smaller groups. However, the generality of this result and connection between kinematics and environment is currently unclear, as recent studies have suggested that, at given stellar mass, the environment does not influence the formation of slow rotators. Here we address this issue by combining a careful quality-assessed sample selection with two-dimensional stellar kinematics from a large galaxy survey and a novel photometric classification approach where kinematics are unavailable. We obtain the first complete census of the location of massive slow rotators in ten large clusters: in all cases, slow rotators are extremely rare and generally trace the clusters density peaks. This result unambiguously establishes that massive slow rotators are the relics of violent hierarchical cluster formation.
- [49] arXiv:1911.06134 [pdf, other]
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Title: Cherenkov Telescope Array potential in the search for Galactic PeVatronsComments: 8 pages, 4 figures, Proceedings of ICRC 2019Journal-ref: PoS(ICRC2019)618Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
One of the major scientific objectives of the future Cherenkov Telescope Array (CTA) Observatory is the search for PeVatrons. PeVatrons are cosmic-ray factories able to accelerate nuclei at least up to the knee feature seen in the spectrum of cosmic rays measured near the Earth. CTA will perform a survey of the full Galactic plane at TeV energies and beyond with unprecedented sensitivity. The determination of efficient criteria to identify PeVatron candidates during the survey is essential in order to trigger further dedicated observations. Here, we present results from a study based on simulations to determine these criteria. The outcome of the study is a PeVatron figure of merit, defined as a metric that provides relations between spectral parameters and spectral cutoff energy lower limits. In addition, simulations of the PeVatron candidate HESS J1641$-$463 and its parental particle spectrum are presented and discussed. Eventually, our work is applied to simulated population of Galactic PeVatrons, with the aim to determine the sensitivity of CTA.
- [50] arXiv:1911.06163 [pdf, other]
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Title: Contribution of starburst nuclei to the diffuse gamma-ray and neutrino fluxComments: 13 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
In nuclei of starburst galaxies, the combination of an enhanced rate of supernova explosions and a high gas density suggests that cosmic rays can be efficiently produced, and that most of them lose their energy before escaping these regions, resulting in a large flux of secondary products, including neutrinos. Although the flux inferred from an individual starburst region is expected to be well below the sensitivity of current neutrino telescopes, such sources may provide a substantial contribution to the diffuse neutrino flux measured by IceCube.
Here we compute the gamma-ray and neutrino flux due to starburst galaxies based on a physical model of cosmic ray transport in a starburst nucleus, and accounting for the redshift evolution of the number density of starburst sources as inferred from recent measurements of the star formation rate. The model accounts for gamma-ray absorption both inside the sources and in the intergalactic medium. The latter process is responsible for electromagnetic cascades, which also contribute to the diffuse gamma-ray background at lower energies. The conditions for acceleration of cosmic ray protons up to energies exceeding $ \sim 10 \, \rm PeV$ in starburst regions, necessary for the production of PeV neutrinos, are investigated in a critical way. We show that starburst nuclei can account for the diffuse neutrino flux above $\sim 200 \, \rm TeV$, thereby producing $\lesssim 40 \%$ of the extragalactic diffuse gamma-ray background. Below $\sim 200 \, \rm TeV$, the flux from starburst appears to be somewhat lower than the observed one, where both the Galactic contribution and the flux of atmospheric neutrinos may account for the difference. - [51] arXiv:1911.06210 [pdf, ps, other]
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Title: Review of Zeeman Effect Observations of Regions of Star FormationComments: 33 pages, 6 figuresJournal-ref: Frontiers in Astronomy and Space Sciences, 6, 66Subjects: Astrophysics of Galaxies (astro-ph.GA)
(Edited for length) The Zeeman effect is the only observational technique available to measure directly the strength of magnetic fields in regions of star formation. We review the physics of the Zeeman effect and its practical use in both extended gas and in masers. We discuss observational results for the five species for which the Zeeman effect has been detected in the ISM -- H~I, OH, and CN in extended gas and OH, CH$_3$OH, and H$_2$O in masers. These species span densities from $\sim10$ cm$^{-3}$ to $\sim10^{10}$ cm $^{-3}$, which allows magnetic fields to be measured over the full range of cloud densities. However, there are significant limitations, including that only the line-of-sight component of the magnetic field strength can usually be measured and that there are often significant uncertainties about the physical conditions being sampled, particularly for masers. We discuss statistical methods to partially overcome these limitations. The results of Zeeman observations are that the mass to magnetic flux ratio is subcritical (gravity dominates magnetic support) at lower densities but supercritical for $N_H \gtrsim 10^{22}$ cm$^{-2}$. Above $n_H\sim 300$ cm$^{-3}$, which is roughly the density at which clouds typically become self-gravitating, the strength of magnetic fields increases approximately as $B \propto n^{2/3}$, which suggest that magnetic fields do not provide significant support at high densities. This is consistent with high-density clouds being supercritical. However, magnetic fields have a large range in strengths at any given density, so the role of magnetic fields should differ significantly from one cloud to another. And for maser regions the dependence of field strength on density may have a slightly lower slope. Turbulent reconnection theory seems to best match the Zeeman observational results.
- [52] arXiv:1911.06218 [pdf, other]
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Title: A Microlensing Accretion Disk Size Measurement in the Lensed Quasar WFI 2026-4536Authors: Matthew A. Cornachione, Christopher W. Morgan, Martin Millon, Misty C. Bentz, Frederic Courbin, Vivien Bonvin, Emilio E. FalcoComments: 26 pages, 8 figures, Appendix with data table, pg 12-25Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We use thirteen seasons of R-band photometry from the 1.2m Leonard Euler Swiss Telescope at La Silla to examine microlensing variability in the quadruply-imaged lensed quasar WFI 2026-4536. The lightcurves exhibit ${\sim}\,0.2\,\text{mag}$ of uncorrelated variability across all epochs and a prominent single feature of ${\sim}\,0.1\,\text{mag}$ within a single season. We analyze this variability to constrain the size of the quasar's accretion disk. Adopting a nominal inclination of 60$^\text{o}$, we find an accretion disk scale radius of $\log(r_s/\text{cm}) = 15.74^{+0.34}_{-0.29}$ at a rest-frame wavelength of $2043\,\unicode{xC5}$, and we estimate a black hole mass of $\log(M_{\text{BH}}/M_{\odot}) = 9.18^{+0.39}_{-0.34}$, based on the CIV line in VLT spectra. This size measurement is fully consistent with the Quasar Accretion Disk Size - Black Hole Mass relation, providing another system in which the accretion disk is larger than predicted by thin disk theory.
- [53] arXiv:1911.06243 [pdf, other]
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Title: Going deep with Minkowski functionals of convergence mapsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Stage IV lensing surveys promise to make available an unprecedented amount of excellent data which will represent a huge leap in terms of both quantity and quality. This will open the way to the use of novel tools, which go beyond the standard second order statistics probing the high order properties of the convergence field. We discuss the use of Minkowski Functionals (MFs) as complementary probes to increase the lensing Figure of Merit (FoM), for a survey made out of a wide total area $A_{\rm{tot}}$ imaged at a limiting magnitude $\rm{mag_{W}}$ containing a subset of area $A_{\rm{deep}}$ where observations are pushed to a deeper limiting magnitude $\rm{mag_{D}}$. We present an updated procedure to match the theoretically predicted MFs to the measured ones, taking into account the impact of map reconstruction from noisy shear data. We validate this renewed method against simulated data sets with different source redshift distributions and total number density, setting these quantities in accordance with the depth of the survey. We can then rely on a Fisher matrix analysis to forecast the improvement in the FoM due to the joint use of shear tomography and MFs under different assumptions on $(A_{\rm{tot}},\,A_{\rm{deep}},\,\rm{mag_{D}})$, and the prior on the MFs nuisance parameters. It turns out that MFs can provide a valuable help in increasing the FoM of the lensing survey, provided the nuisance parameters are known with a non negligible precision. What is actually more interesting is the possibility to compensate for the loss of FoM due to a cut in the multipole range probed by shear tomography, which makes the results more robust against uncertainties in the modeling of nonlinearities. This makes MFs a promising tool to both increase the FoM and make the constraints on the cosmological parameters less affected by theoretical systematic effects.
- [54] arXiv:1911.06250 [pdf, other]
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Title: Debris disks around stars in the NIKA2 eraAuthors: J.-F. Lestrade, J.-C. Augereau, M. Booth, R. Adam, P. Ade, P. Andre A., Andrianasolo, H. Aussel, A. Beelen, A. Benoit, A. Bideaud, O. Bourrion, M. Calvo, A. Catalano, B. Comis, M. De Petris, F.-X. Desert, S. Doyle, E. F. C. Driessen, A. Gomez, J. Goupy W. Holland, F. Keruzore, C. Kramer, B. Ladjelate, G. Lagache, S. Leclercq, C. Lefevre, J.F. Macias-Perez, P. Mauskopf, F. Mayet, A. Monfardini, L. Perotto, G. Pisano, N. Ponthieu, V. Reveret, A. Ritacco, C. Romero, H. Roussel, F. Ruppin, K. Schuster, S. Shu, A. Sievers, P. Thebault, C. Tucker, R. ZylkaComments: 6 pages, 8 figures, to appear in the proceedings of the international conference entitled mm Universe @ NIKA2, Grenoble (France), June 2019, EPJ Web of conferencesSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The new NIKA2 camera at the IRAM 30m radiotelescope was used to observe three known debris disks in order to constrain the SED of their dust emission in the millimeter wavelength domain. We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the Rayleigh-Jeans regime (lambda^{-2}), unlike the steeper spectra (lambda^{-3}) measured in the submillimeter-wavelength domain for two of the three disks $-$ around the stars Vega and HD107146. We provide a succesful proof of concept to model this spectral inversion in using two populations of dust grains, those smaller and those larger than a grain radius a0 of 0.5mm. This is obtained in breaking the slope of the size distribution and the functional form of the absorption coefficient of the standard model at a0. The third disk - around the star HR8799 - does not exhibit this spectral inversion but is also the youngest.
- [55] arXiv:1911.06271 [pdf, ps, other]
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Title: Sublimation of Water Ice from a Population of Large, Long-Lasting Grains Near the Nucleus of 2I/Borisov?Authors: Zdenek SekaninaComments: 6 pages, 3 figures, 1 tableSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Potential effects of sublimation of water ice from very slowly moving millimeter-sized and larger grains, a product of activity at 10 AU or farther from the Sun driven presumably by annealing of amorphous water ice, are investigated by comparing 2I/Borisov with a nominal Oort Cloud comet of equal perihelion distance of 2 AU. This comparison suggests that the strongly hyperbolic motion of 2I mitigates the integrated sublimation effect. The population of these grains near the nucleus of 2I is likely to have been responsible for the comet appearing excessively bright in pre-discovery images at 5-6 AU from the Sun, when the sublimation rate was exceedingly low, as well as for the prominent nuclear condensation more recently. All grains smaller then 2-3 cm across had been devolatilized by mid-October 2019 and some subjected to rapid disintegration. This left only larger chunks of the initial icy-dust halo contributing to the comet's suspected hyperactivity. Sublimation of water ice from the nucleus has been increasing since the time of discovery, but the rate has not been high enough to exert a measurable nongravitational acceleration on the orbital motion of 2I/Borisov.
- [56] arXiv:1911.06274 [pdf, ps, other]
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Title: Information in the Reflected Light Spectra of Widely Separated Giant ExoplanetsAuthors: Renyu HuComments: ApJ acceptedSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Giant exoplanets located >1 AU away from their parent stars have atmospheric environments cold enough for water and/or ammonia clouds. We have developed a new equilibrium cloud and reflected light spectrum model, ExoREL, for widely separated giant exoplanets. The model includes the dissolution of ammonia in liquid water cloud droplets, an effect studied for the first time for exoplanets. While preserving the causal relationship between temperature and cloud condensation, ExoREL is simple and fast to enable efficient exploration of parameter space. Using the model, we find that the mixing ratio of methane and the cloud top pressure of a giant exoplanet can be uniquely determined from a single observation of its reflected light spectrum at wavelengths less than 1 micron if it has a cloud deck deeper than ~0.3 bars. This measurement is enabled by the weak and strong bands of methane and requires a signal-to-noise ratio of 20. The cloud pressure once derived, provides information about the internal heat flux of the planet. Importantly, we find that for a low, Uranus-like internal heat flux, the planet can have a deep liquid water cloud, which will sequester ammonia and prevent the formation of the ammonia cloud that would otherwise be the uppermost cloud layer. This newly identified phenomenon causes a strong sensitivity of the cloud top pressure on the internal heat flux. Reflected light spectroscopy from future direct-imaging missions therefore not only measure the atmospheric abundances but also characterize the thermal evolution of giant exoplanets.
- [57] arXiv:1911.06277 [pdf, other]
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Title: The NIKA polarimeter on science targets. Crab nebula observations at 150 GHz and dual-band polarization images of Orion Molecular Cloud OMC-1Authors: A. Ritacco, R. Adam, P. Ade, P. André, A. Andrianasolo, H. Aussel, A. Beelen, A. Benoît, A. Bideaud, O. Bourrion, M. Calvo, A. Catalano, B. Comis, M. De Petris, F.-X. Désert, S. Doyle, E. F. C. Driessen, A. Gomez, J. Goupy, F. Kéruzoré, C. Kramer, B. Ladjelate, G. Lagache, S. Leclercq, J.-F. Lestrade, J.F. Macías-Pérez, P. Mauskopf, A. Maury, F. Mayet, A. Monfardini, L. Perotto, G. Pisano, N. Ponthieu, V. Revéret, C. Romero, H. Roussel, F. Ruppin, K. Schuster, S. Shu, A. Sievers, C. Tucker, R. ZylkaComments: to appear in the proceedings of the international conference entitled mm Universe @ NIKA2, Grenoble (France), June 2019, EPJ Web of conferencesSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present here the polarization system of the NIKA camera and give a summary of the main results obtained and performed studies on Orion and the Crab nebula. The polarization system was equipped with a room temperature continuously rotating multi-mesh half wave plate and a grid polarizer facing the NIKA cryostat window. NIKA even though less sensitive than NIKA2 had polarization capability in both 1 and 2 millimiter bands. NIKA polarization observations demonstrated the ability of such a technology in detecting the polarization of different targets, compact and extended sources like the Crab nebula and Orion Molecular Cloud region OMC-1. These measurements together with the developed techniques to deal with systematics, opened the way to the current observations of NIKA2 in polarization that will provide important advances in the studies of galactic and extra-galactic emission and magnetic fields.
- [58] arXiv:1911.06281 [pdf, other]
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Title: Thermal Friction as a Solution to the Hubble TensionComments: 5 pages, 2 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
The phenomenological early dark energy (EDE) provides a promising solution to the Hubble tension in the form of an extra beyond-$\Lambda$CDM component that acts like a cosmological constant at early times ($z \geq 3000$) and then dilutes away as radiation or faster. We show that a rolling axion coupled to a non-Abelian gauge group, which we call the `dissipative axion' (DA), mimics this phenomenological EDE at the background level and presents a particle-physics model solution to the Hubble tension, while also eliminating fine-tuning in the choice of scalar-field potential. We compare the DA model to the EDE fluid approximation at the background level and comment on their similarities and differences. We determine that CMB observables sensitive only to the background evolution of the Universe are expected to be similar in the two models, strengthening the case for exploring the perturbations of the DA as well as for this model to provide a viable solution to the Hubble tension.
Cross-lists for Fri, 15 Nov 19
- [59] arXiv:1811.02141 (cross-list from cs.LG) [pdf, other]
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Title: Extended Isolation ForestComments: 12 pages; 21 figuresSubjects: Machine Learning (cs.LG); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (stat.ML)
We present an extension to the model-free anomaly detection algorithm, Isolation Forest. This extension, named Extended Isolation Forest (EIF), resolves issues with assignment of anomaly score to given data points. We motivate the problem using heat maps for anomaly scores. These maps suffer from artifacts generated by the criteria for branching operation of the binary tree. We explain this problem in detail and demonstrate the mechanism by which it occurs visually. We then propose two different approaches for improving the situation. First we propose transforming the data randomly before creation of each tree, which results in averaging out the bias. Second, which is the preferred way, is to allow the slicing of the data to use hyperplanes with random slopes. This approach results in remedying the artifact seen in the anomaly score heat maps. We show that the robustness of the algorithm is much improved using this method by looking at the variance of scores of data points distributed along constant level sets. We report AUROC and AUPRC for our synthetic datasets, along with real-world benchmark datasets. We find no appreciable difference in the rate of convergence nor in computation time between the standard Isolation Forest and EIF.
- [60] arXiv:1911.05778 (cross-list from hep-th) [pdf, other]
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Title: Comments on the CKN BoundComments: 7 pagesSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Cohen, Kaplan, and Nelson (CKN) conjectured that the UV and IR cutoffs of effective quantum field theories coupled to gravity are not independent, but are connected by the physics of black holes. We interpret the CKN bound as a scale-dependent depletion of the QFT density of states and discuss various aspects of the bound on small and large scales. For laboratory experiments, we argue that the bound provides small corrections to ordinary quantum field theory, which we estimate to be of order $m_e/M_p$ for $g-2$ of the electron. On large scales, we suggest a modification of the CKN bound due to the presence of cosmological horizons and discuss the connection with entropy bounds.
- [61] arXiv:1911.05793 (cross-list from gr-qc) [pdf, other]
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Title: Extended FLRW Models: dynamical cancellation of cosmological anisotropiesComments: 31 pages, 2 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph)
We investigate a corner of the Bianchi models that has not received much attention: "extended FLRW models" (eFLRW) defined as a cosmological model with underlying anisotropic Bianchi geometry that nevertheless expands isotropically and can be mapped onto a reference FLRW model with the same expansion history. In order to investigate the stability and naturalness of such models in a dynamical systems context, we consider spatially homogeneous models that contain a massless scalar field $\varphi$ and a non-tilted perfect fluid obeying an equation of state $p=w\rho$. Remarkably, we find that matter anisotropies and geometrical anisotropies tend to cancel out dynamically. Hence, the expansion is asymptotically isotropic under rather general conditions. Although extended FLRW models require a special matter sector with anisotropies that are 'fine-tuned" relative to geometrical anisotropies, our analysis shows that such solutions are dynamically preferred attractors in general relativity. Specifically, we prove that all locally rotationally symmetric Bianchi type III universes with space-like $\nabla_\mu\varphi$ are asymptotically shear-free, for all $w\in[-1,1]$. Moreover, all shear-free equilibrium sets with anisotropic spatial curvature are proved to be stable with respect to all homogeneous perturbations for $w\geq -1/3$.
- [62] arXiv:1911.05860 (cross-list from physics.ao-ph) [pdf, other]
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Title: Combining Thermodynamic and Dynamic Perspectives of Tropical Circulation to Constrain the Downdraft Width of the Hadley CellComments: 13 pages (4200 words) main text, 3 figures 16 pages Supplementary Info, 10 figuresSubjects: Atmospheric and Oceanic Physics (physics.ao-ph); Earth and Planetary Astrophysics (astro-ph.EP); Fluid Dynamics (physics.flu-dyn)
In the Hadley circulation downdraft, to leading order vertical potential temperature advection balances the "effective" heating, comprising the sum of diabatic heating and eddy heat flux divergence, placing a thermodynamic constraint on vertical velocity. Insofar as downdraft-averaged effective heating and static stability do not vary with planetary parameters, neither can vertical velocity --- an "omega governor." Separately, in the eddy-driven (i.e. small-Rossby-number) limit, extratropical eddy stresses also constrain the cell strength dynamically. We combine these thermodynamic and dynamic mechanisms to derive new and identical scalings for the downdraft width and overturning strength with rotation rate. With the omega governor maintaining fixed vertical velocity, the downdraft must narrow or widen in order to attain the overturning strength dictated by the eddy stresses. We evaluate the validity of this new scaling using model simulations over a broad range of rotation rates and model forcing schemes.
- [63] arXiv:1911.05937 (cross-list from physics.plasm-ph) [pdf, ps, other]
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Title: Ultrafast Wave-Particle Energy Transfer in the Collapse of Standing Whistler WavesComments: 11 pages, 9 figures, 1 table, accepted for publication in PRESubjects: Plasma Physics (physics.plasm-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Space Physics (physics.space-ph)
Efficient energy transfer from electromagnetic waves to ions has been demanded to control laboratory plasmas for various applications and could be useful to understand the nature of space and astrophysical plasmas. However, there exists a severe unsolved problem that most of the wave energy is converted quickly to electrons, but not to ions. Here, an energy conversion process to ions in overdense plasmas associated with whistler waves is investigated by numerical simulations and theoretical model. Whistler waves propagating along a magnetic field in space and laboratories often form the standing waves by the collision of counter-propagating waves or through the reflection. We find that ions in the standing whistler waves acquire a large amount of energy directly from the waves in a short timescale comparable to the wave oscillation period. Thermalized ion temperature increases in proportion to the square of the wave amplitude and becomes much higher than the electron temperature in a wide range of wave-plasma conditions. This efficient ion-heating mechanism applies to various plasma phenomena in space physics and fusion energy sciences.
- [64] arXiv:1911.06040 (cross-list from gr-qc) [pdf, ps, other]
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Title: Cuscuton gravity as a classically stable limiting curvature theoryComments: 23 pagesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
Finding effective theories of modified gravity that can resolve cosmological singularities and avoid other physical pathologies such as ghost and gradient instabilities has turned out to be a rather difficult task. The concept of limiting curvature, where one bounds a finite number of curvature-invariant functions thanks to constraint equations, is a promising avenue in that direction, but its implementation has only led to mixed results. Cuscuton gravity, which can be defined as a special subclass of $k$-essence theory for instance, is a minimal modification of gravity since it does not introduce any new degrees of freedom on a cosmological background. Importantly, it naturally incorporates the idea of limiting curvature. Accordingly, models of cuscuton gravity are shown to possess non-singular cosmological solutions and those appear stable at first sight. Yet, various subtleties arise in the perturbations such as apparent divergences, e.g., when the Hubble parameter crosses zero. We revisit the cosmological perturbations in various gauges and demonstrate that the stability results are robust even at those crossing points, although certain gauges are better suited to analyze the perturbations. In particular, the spatially-flat gauge is found to be ill defined when $H=0$. Otherwise, the sound speed is confirmed to be generally close to unity in the ultraviolet, and curvature perturbations are shown to remain essentially constant in the infrared throughout a bounce phase. Perturbations for a model of extended cuscuton (as a subclass of Horndeski theory) are also studied and similar conclusions are recovered.
- [65] arXiv:1911.06050 (cross-list from gr-qc) [pdf, other]
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Title: Including higher order multipoles in gravitational-wave models for precessing binary black holesComments: 13 pages, 8 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Solar and Stellar Astrophysics (astro-ph.SR)
Estimates of the source parameters of gravitational-wave (GW) events produced by compact binary mergers rely on theoretical models for the GW signal. We present the first frequency-domain model for inspiral, merger and ringdown of the GW signal from precessing binary-black-hole systems that also includes multipoles beyond the leading-order quadrupole. Our model, {\tt PhenomPv3HM}, is a combination of the higher-multipole non-precessing model {\tt PhenomHM} and the spin-precessing model {\tt PhenomPv3} that includes two-spin precession via a dynamical rotation of the GW multipoles. We validate the new model by comparing to a large set of precessing numerical-relativity simulations and find excellent agreement across the majority of the parameter space they cover. For mass ratios $<5$ the mismatch improves, on average, from $\sim6\%$ to $\sim 2\%$ compared to {\tt PhenomPv3} when we include higher multipoles in the model. However, we find mismatches $\sim8\%$ for the mass-ratio $6$ and highly spinning simulation. As a first application of the new model we have analysed the binary black hole event GW170729. We find larger values for the primary black hole mass of $58.25^{+11.73}_{-12.53} \, M_\odot$ (90\% credible interval). The lower limit ($\sim 46 \, M_\odot$) is comparable to the proposed maximum black hole mass predicted by different stellar evolution models due to the pulsation pair-instability supernova (PPISN) mechanism. If we assume that the primary \ac{BH} in GW170729 formed through a PPISN then out of the four PPISN models we considered only the model of Woosley (2017) is consistent with our mass measurements at the 90\% level.
- [66] arXiv:1911.06058 (cross-list from hep-th) [pdf, ps, other]
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Title: Fundamental Physics, the Swampland of Effective Field Theory and Early Universe CosmologyAuthors: Robert Brandenberger (McGill University)Comments: Talk at the Int. Symposium Quantum Theory and Symmetry XI (July 1st to 5th, 2019, CRM, Univ. of Montreal), to be published in the proceedings (CRM Series on Mathematical Physics, Springer, 2020). 9 pagesSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Cosmological inflation is not the only early universe scenario consistent with current observational data. I will discuss the criteria for a successful early universe cosmology, compare a couple of the proposed scenarios (inflation, bouncing cosmologies, and the {\it emergent} scenario), focusing on how future observational data will be able to distinguish between them. I will argue that we need to go beyond effective field theory in order to understand the early universe, and that principles of superstring theory will yield a nonsingular cosmology.
- [67] arXiv:1911.06059 (cross-list from gr-qc) [pdf, other]
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Title: Black holes, Planckian granularity, and the changing cosmological `constant'Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Theory (hep-th)
In a recent work we have argued that nosy energy momentum diffusion due to space-time discreteness at the Planck scale (naturally expected to arise from quantum gravity) can be responsible for the generation of a cosmological constant during the electro-weak phase transition era of the cosmic evolution. Simple dimensional analysis and an effectively Brownian description of the propagation of fundamental particles on a granular background yields a cosmological constant of the order of magnitude of the observed value, without fine tuning. While the energy diffusion is negligible for matter in standard astrophysical configurations (from ordinary stars to neutron stars) here we argue that a similar diffusion mechanism could, nonetheless be important for black holes. If such effects are taken into account two observational puzzles might be solved by a single mechanism: the `$H_0$ tension' and the relatively low rotational spin of the black holes detected via gravitational wave astronomy.
- [68] arXiv:1911.06100 (cross-list from hep-th) [pdf, other]
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Title: Effective scalar potential in asymptotically safe quantum gravityAuthors: C. WetterichComments: 37 pages, 26 figuresSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
We investigate the shape of the effective potential for scalar fields at and near the ultraviolet fixed point of asymptotically safe quantum gravity. We find scaling solutions with a completely flat potential and vanishing gauge and Yukawa couplings. Nonvanishing gauge couplings can induce spontaneous symmetry breaking due to a potential minimum at nonzero field values. In contrast, Yukawa couplings to fermions tend to stabilize a minimum at zero field values. A nonminimal coupling between the scalar field and gravity is associated to a field-dependent effective Planck mass. It can induce spontaneous symmetry breaking. In general, nonzero gauge, Yukawa or nonminimal couplings prevent the scaling potential to be completely flat. For the standard model coupled to asymptotically safe quantum gravity the non-minimal Higgs-curvature coupling is bound to be small, $\xi_{\infty} \lesssim 10^{-3}$, in contrast to large values $\xi_{\infty} > 1$ often assumed for Higgs inflation. We also discuss small modifications of the predicted value for the top quark mass due to nonzero gauge and Yukawa couplings.
- [69] arXiv:1911.06148 (cross-list from gr-qc) [pdf, other]
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Title: Trans-Planckian censorship of multi-stage inflation and dark energyComments: 12 pages, 4 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We explore the bound of Trans-Planckian censorship conjecture on the inflation model with multiple stages. We show that if the first inflationary stage is responsible for the primordial perturbations at CMB window, the efolding number of each subsequent stage will be bounded by the energy scale of the first stage. This seems to imply that the lifetime of current accelerated expanding era (regarded as one of the multiple inflationary stages) might be a probe for distinguishing inflation from its alternatives. We also present a multi-stage inflation model in a landscape consisting of Anti-de Sitter vacua separated by the potential barriers.
- [70] arXiv:1911.06228 (cross-list from gr-qc) [pdf, ps, other]
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Title: The maximum turnaround radius for axisymmetric cosmic structuresComments: v1, 13ppSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We compute the leading order effect of non-sphericity on the maximum size $R_{\rm TA,max}$ of realistic large scale bound cosmic structures in the framework of $\Lambda{\rm CDM}$. As a first step, we focus on static or stationary axisymmetric cases, in which the departure from spherical symmetry is due to the mass density distribution or to the angular momentum of the structure. Modeled by a Kerr-de Sitter spacetime, the fractional change $\delta R_{\rm TA,max}(\theta)/R^{(0)}_{\rm TA,max}$ of $R_{\rm TA,max}$ of a given rotating cosmic structure, compared to a spherical one with the same mass, is negative for all values of the polar angle $\theta$, and its average over the angles is $\langle \delta R_{\rm TA,max}(\theta)/R^{(0)}_{\rm TA,max}\rangle \simeq -a^2/(3 R^{(0)\, 2}_{\rm TA,max})\approx -{\cal O}(v^2_{\rm out}/c^2)$, with $a=J/M$ the parameter angular momentum per unit mass of the Kerr-de Sitter background and $v_{\rm out}$ the azimuthal speed of the outmost members of the structure. In contrast, in the case of a homogeneous static spheroidal distribution the leading order effect of its eccentricity on $\langle \delta R_{\rm TA,max}(\theta)\rangle$ vanishes for all values of the eccentricity parameter.
- [71] arXiv:1911.06259 (cross-list from quant-ph) [pdf, other]
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Title: Restricted Boltzmann Machines for galaxy morphology classification with a quantum annealerComments: 13 pages; LaTeX; 11 figuresSubjects: Quantum Physics (quant-ph); Astrophysics of Galaxies (astro-ph.GA); Machine Learning (cs.LG)
We present the application of Restricted Boltzmann Machines (RBMs) to the task of astronomical image classification using a quantum annealer built by D-Wave Systems. Morphological analysis of galaxies provides critical information for studying their formation and evolution across cosmic time scales. We compress the images using principal component analysis to fit a representation on the quantum hardware. Then, we train RBMs with discriminative and generative algorithms, including contrastive divergence and hybrid generative-discriminative approaches. We compare these methods to Quantum Annealing (QA), Markov Chain Monte Carlo (MCMC) Gibbs Sampling, Simulated Annealing (SA) as well as machine learning algorithms like gradient boosted decision trees. We find that RBMs implemented on D-wave hardware perform well, and that they show some classification performance advantages on small datasets, but they don't offer a broadly strategic advantage for this task. During this exploration, we analyzed the steps required for Boltzmann sampling with the D-Wave 2000Q, including a study of temperature estimation, and examined the impact of qubit noise by comparing and contrasting the original D-Wave 2000Q to the lower-noise version recently made available. While these analyses ultimately had minimal impact on the performance of the RBMs, we include them for reference.
- [72] arXiv:1911.06295 (cross-list from math.AP) [pdf, ps, other]
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Title: Structural stability of shock waves and current-vortex sheets in shallow water magnetohydrodynamicsAuthors: Yuri TrakhininComments: 18 pagesSubjects: Analysis of PDEs (math.AP); Solar and Stellar Astrophysics (astro-ph.SR); Mathematical Physics (math-ph)
We study the structural stability of shock waves and current-vortex sheets in shallow water magnetohydrodynamics (SMHD) in the sense of the local-in-time existence and uniqueness of discontinuous solutions satisfying corresponding jump conditions. The equations of SMHD form a symmetric hyperbolic system which is formally analogous to the system of 2D compressible elastodynamics for particular nonphysical deformations. Using this analogy and the recent results in [Morando A., Trakhinin Y., Trebeschi P. Math. Ann. (2019), https://doi.org/10.1007/s00208-019-01920-6] for shock waves in 2D compressible elastodynamics, we prove that shock waves in SMHD are structurally stable if and only if the fluid height increases across the shock front. For current-vortex sheets the fluid height is continuous whereas the tangential components of the velocity and the magnetic field may have a jump. Applying a so-called secondary symmetrization of the symmetric system of SMHD equations, we find a condition sufficient for the structural stability of current-vortex sheets.
- [73] arXiv:1911.06301 (cross-list from hep-ph) [pdf, other]
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Title: Neutrino Oscillation in Dense MatterAuthors: Shu LuoComments: 34 pages, 13 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
As the increasing of neutrino energy or matter density, the neutrino oscillation in matter may undergo "vacuum-dominated", "resonance" and "matter-dominated" three different stages successively. Neutrinos endure very different matter effects, and therefore present very different oscillation behaviors in these three different cases. In this paper, we focus on the less discussed matter-dominated case (i.e., $|A^{}_{\rm CC}| \gg |\Delta m^{2}_{31}|$), study the effective neutrino mass and mixing parameters as well as neutrino oscillation probabilities in dense matter using the perturbation theory. We find that as the matter parameter $|A^{}_{\rm CC}|$ growing larger, the effective mixing matrix in matter $\tilde{V}$ evolves approaching a fixed $3 \times 3$ constant real matrix which is free of CP violation and can be described using only one simple mixing angle $\tilde{\theta}$ which is independent of $A^{}_{\rm CC}$. As for the neutrino oscillation behavior, $\nu^{}_{e}$ decoupled in the matter-dominated case due to its intense charge-current interaction with electrons while a two-flavor oscillation are still presented between $\nu^{}_{\mu}$ and $\nu^{}_{\tau}$. Numerical analysis are carried on to help understanding the salient features of neutrino oscillation in matter as well as confirming the validity of those concise approximate formulas we obtained. At the end of this paper, we make a very bold comparison of the oscillation behaviors between neutrinos passing through the Earth and passing through a typical white dwarf to give some embryo thoughts on under what circumstances these studies will be applied and put forward the interesting idea of possible "neutrino lensing" effect.
Replacements for Fri, 15 Nov 19
- [74] arXiv:1711.10590 (replaced) [pdf, other]
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Title: Stellar populations of galaxies in the ALHAMBRA survey up to $z \sim 1$. II. Stellar content of quiescent galaxies within the dust-corrected stellar mass$-$colour and the $UVJ$ colour$-$colour diagramsAuthors: L.A. Díaz-García, A.J. Cenarro, C. López-Sanjuan, I. Ferreras, M. Cerviño, A. Fernández-Soto, I. Márquez, M. Pović, I. San Roman, K. Viironen, M. Moles, D. Cristóbal-Hornillos, E. Alfaro, T. Aparicio-Villegas, N. Benítez, T. Broadhurst, J. Cabrera-Caño, F.J. Castander, J. Cepa, R.M. González Delgado, C. Husillos, L. Infante, J.A.L. Aguerri, J. Masegosa, A. Molino, A. del Olmo, J. Perea, F. Prada, J.M. Quintana, V.J. MartínezComments: (37 pages, 29 figures, accepted for publication in A&A)Journal-ref: A&A 631, A156 (2019)Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [75] arXiv:1901.02418 (replaced) [pdf, other]
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Title: Cosmology with kSZ: breaking the optical depth degeneracy with Fast Radio BurstsComments: 7 pages, 4 figures, minor changes for clarity, accepted for publication in Physical Review DSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [76] arXiv:1901.06052 (replaced) [pdf, other]
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Title: Can a black hole-neutron star merger explain GW170817, AT2017gfo, GRB170817A?Journal-ref: Phys. Rev. D 100, 043011 (2019)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [77] arXiv:1903.08585 (replaced) [pdf, ps, other]
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Title: Numerical Simulations of Gravitational Waves from Early-Universe TurbulenceComments: 5 pages, 5 figures, 1 table, + 5 pages supplemental material, with 3 additional figures and 1 additional table, submitted to PRLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [78] arXiv:1903.11363 (replaced) [pdf, other]
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Title: Neutrinos and gamma rays from long-lived mediator decays in the SunComments: 31 pages, 16 figures, 3 tables; v2: Matches version published in JCAPJournal-ref: JCAP11 (2019) 011Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
- [79] arXiv:1904.00436 (replaced) [pdf, other]
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Title: Attitude and orbit coupling of planar helio-stable solar sailsComments: 36 pages, 31 figuresSubjects: Space Physics (physics.space-ph); Earth and Planetary Astrophysics (astro-ph.EP); Dynamical Systems (math.DS)
- [80] arXiv:1904.00984 (replaced) [pdf, other]
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Title: Primordial black hole formation and abundance: contribution from the non-linear relation between the density and curvature perturbationComments: 29 pages, 7 figures. V2: updated to match published versionJournal-ref: JCAP11(2019)012Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [81] arXiv:1904.04684 (replaced) [pdf, other]
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Title: Comparison of SEDs of very massive radio-loud and radio-quiet AGNComments: Submitted to MNRAS, 11 pages, 14 figures, Comments are welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
- [82] arXiv:1904.11070 (replaced) [pdf, other]
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Title: RascalC: A Jackknife Approach to Estimating Single and Multi-Tracer Galaxy Covariance MatricesComments: 29 pages, 8 figures. Accepted by MNRAS. Code is available at this http URL with documentation at this http URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [83] arXiv:1906.11299 (replaced) [pdf, other]
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Title: Can Neutron-Star Mergers Explain the r-process Enrichment in Globular Clusters?Authors: Michael Zevin, Kyle Kremer, Daniel M. Siegel, Scott Coughlin, Benny T.-H. Tsang, Christopher P. L. Berry, Vicky KalogeraComments: Published in ApJ. 22 pages, 7 figures, 1 tableJournal-ref: The Astrophysical Journal, 886, 1 (2019)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
- [84] arXiv:1907.08714 (replaced) [pdf, other]
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Title: Neutron star masses in $R^{2}$-gravityComments: 26 pages, 15 figures, pdfLatex, one subsection added and other minor changes, version accepted for publicationJournal-ref: Physics of the Dark Universe 27C (2020) 100411Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [85] arXiv:1907.12402 (replaced) [pdf, ps, other]
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Title: Observational evidence for a local underdensity in the Universe and its effect on the measurement of the Hubble ConstantComments: 11 pages, 17 figures, Astronomy and Astrophysics in pressSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [86] arXiv:1907.13219 (replaced) [pdf, ps, other]
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Title: Observational constraints of $f(Q)$ gravityComments: 8 pages, minor additions to Conclusion; typo in author's name corrected; version published in PRDJournal-ref: Phys. Rev. D 100, 104027 (2019)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [87] arXiv:1909.10518 (replaced) [pdf, other]
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Title: COS Observations of the Cosmic Web: A Search for the Cooler Components of a Hot, X-ray Identified FilamentAuthors: Thomas Connor, Fakhri S. Zahedy, Hsiao-Wen Chen, Thomas J. Cooper, John S. Mulchaey, Alexey VikhlininComments: Published in the Astrophysical Journal Letters; 9 Pages, 4 Figures, 1 Table. v2 corrects one referenceJournal-ref: 2019, ApJL, 884, L20Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [88] arXiv:1909.13300 (replaced) [pdf, other]
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Title: Modeling Mg II during Solar Flares. II. Non-equilibrium EffectsComments: 12 pages, 13 figures, accepted in the Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [89] arXiv:1910.10739 (replaced) [pdf, other]
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Title: New Early Dark EnergyComments: 6 pages, 2 figures, 1 table, v2: LCDM bias on reionisation optical depth relaxed, minor improvements of manuscript, references added, plots and data table addedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [90] arXiv:1910.10805 (replaced) [pdf, ps, other]
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Title: Sulphur-Bearing and Complex Organic Molecules in an Infrared Cold CoreAuthors: Pedro P. B. Beaklini, Edgar Mendoza, Carla M. Canelo, Isabel Aleman, Manuel Merello, Shuo Kong, Felipe Navarete, Eduardo Janot-Pacheco, Zulema Abraham, Jacques R.D. Lépine, Amaury A. de Almeida, Amâncio C.S. FriaçaComments: 13 pages, 11 figures. Accept in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
- [91] arXiv:1910.12754 (replaced) [pdf, other]
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Title: Deep XMM-Newton Observations of the Northern Disk of M31 II: The Hot Interstellar MediumAuthors: Patrick J. Kavanagh, Manami Sasaki, Dieter Breitschwerdt, Miguel A. de Avillez, Miroslav D. Filipovic, Timothy Galvin, Frank Haberl, Despina Hatzidimitriou, Martin Henze, Paul P. Plucinsky, Sara Saeedi, Kirill V. Sokolovsky, Benjamin F. WilliamsComments: 21 pages, 12 figures, submitted to Astronomy & Astrophysics, typo correction in co-author nameSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
- [92] arXiv:1911.01457 (replaced) [pdf, other]
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Title: Stochastic Chemical Evolution of Radioactive Isotopes with a Monte Carlo ApproachComments: 25 pages, 11 figures, 4 tables, submitted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [93] arXiv:1911.03257 (replaced) [pdf, other]
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Title: Dust evolution in pre-stellar coresAuthors: Charlène Lefèvre, Laurent Pagani, Bilal Ladjelate, Michiel Min, Hiroyuki Hirashita, Robert ZylkaComments: 6 pages, 5 figures, to appear in the proceedings of the international conference entitled mm Universe @ NIKA2, Grenoble (France), June 2019, EPJ Web of conferencesSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [94] arXiv:1911.04938 (replaced) [pdf, other]
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Title: Time-resolved photometry of the young dipper RX J1604.3-2130A: Unveiling the structure and mass transport through the innermost diskComments: A&A in press. 18 pages plus Online material. Minor corrections with respect to previous versionSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
- [95] arXiv:1911.05196 (replaced) [pdf, other]
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Title: DANCE: Dark matter Axion search with riNg Cavity ExperimentAuthors: Yuta Michimura, Yuka Oshima, Taihei Watanabe, Takuya Kawasaki, Hiroki Takeda, Masaki Ando, Koji Nagano, Ippei Obata, Tomohiro FujitaComments: 4 pages, 2 figures, Proceedings for the 16th International Conference on Topics in Astroparticle and Underground Physics, Toyama, September 9-13, 2019Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Phenomenology (hep-ph)
- [96] arXiv:1911.05598 (replaced) [pdf]
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Title: Chemically-distinct regions within Venus' atmosphere revealed by MESSENGER-measured N2 concentrationsComments: 12 pages (incl. references), 3 figures, plus supplemental online materials with 3 figures and 1 table)Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
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