Astrophysics
New submissions
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New submissions for Fri, 20 Mar 20
- [1] arXiv:2003.08387 [pdf, other]
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Title: Interacting radiation after Planck and its implications for the Hubble TensionComments: 21 pages, 8 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Standard cosmology predicts that prior to matter-radiation equality about 41% of the energy density was in free-streaming neutrinos. In many beyond Standard Model scenarios, however, the amount and free-streaming nature of this component is modified. For example, this occurs in models with new neutrino self-interactions or an additional dark sector with interacting light particles. We consider several extensions of the standard cosmology that include a non-free-streaming radiation component as motivated by such particle physics models and use the final Planck data release to constrain them. This release contains significant improvements in the polarization likelihood which plays an important role in distinguishing free-streaming from interacting radiation species. Fixing the total amount of energy in radiation to match the expectation from standard neutrino decoupling we find that the fraction of free-streaming radiation must be $f_\mathrm{fs} > 0.8$ at 95% CL (combining temperature, polarization and baryon acoustic oscillation data). Allowing for arbitrary contributions of free-streaming and interacting radiation, the effective number of new non-free-streaming degrees of freedom is constrained to be $N_\mathrm{fld} < 0.6$ at 95% CL. Cosmologies with additional radiation are also known to ease the discrepancy between the local measurement and CMB inference of the current expansion rate $H_0$. We show that including a non-free-streaming radiation component allows for a larger amount of total energy density in radiation, leading to a mild improvement of the fit to cosmological data compared to previously discussed models with only a free-streaming component.
- [2] arXiv:2003.08389 [pdf, other]
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Title: Probing Axial Symmetry Breaking in the Galaxy with Gaia Data Release 2Comments: 22 pages, 14 figures, accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We study a set of solar neighborhood ($d < 3$ kpc) stars from Gaia Data Release 2 to determine azimuthal star count differences, i.e., left and right of the line from the Galactic center through the sun - and compare these differences north and south. In this companion paper to Gardner et al. (2020), we delineate our procedures to remove false asymmetries from sampling effects, incompleteness, and/or interloper populations, as this is crucial to tests of axisymmetry. Particularly, we have taken care to make appropriate selections of magnitude, color, in-plane Galactocentric radius and Galactic $|b|$ and $|z|$. We find that requiring parallax determinations of high precision induces sampling biases, so that we eschew such requirements and exclude, e.g., regions around the lines of sight to the Magellanic clouds, along with their mirror-image lines of sight, to ensure well-matched data sets. After making conservative cuts, we demonstrate the existence of azimuthal asymmetries, and find differences in those, north and south. These asymmetries give key insights into the nature and origins of the perturbations on Galactic matter, allowing us to assess the relative influence of the Magellanic Clouds (LMC & SMC), the Galactic bar, and other masses on the Galactic mass distribution, as described in Gardner et al. (2020). The asymmetry's radial dependence reveals variations that we attribute to the Galactic bar, and it changes sign at a radius of $(0.95 \pm 0.03) R_0$, with $R_0$ the Sun-Galactic-Center (GC) distance, to give us the first direct assessment of the outer Lindblad resonant radius.
- [3] arXiv:2003.08390 [pdf, other]
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Title: Multiphase Gas and the Fractal Nature of Radiative Turbulent Mixing LayersComments: 11 pages, 5 figures, submitted to ApJL. Movies can be found here this https URLSubjects: Astrophysics of Galaxies (astro-ph.GA)
A common situation in galactic and intergalactic gas involves cold dense gas in motion relative to hot diffuse gas. Kelvin-Helmholtz instability creates a turbulent mixing layer and populates the intermediate-temperature phase, which often cools rapidly. The energy lost to cooling is balanced by the advection of hot high enthalpy gas into the mixing layer, resulting in growth and acceleration of the cold phase. This process may play a major role in determining the interstellar medium and circumgalactic medium phase structure, and accelerating cold gas in galactic winds and cosmic filaments. Cooling in these mixing layers occurs in a thin corrugated sheet, which we argue has an area with fractal dimension $D=5/2$ and a thickness that adjusts to match the hot phase mixing time to the cooling time. These cooling sheet properties form the basis of a new model for how the cooling rate and hot gas inflow velocity depend on the size $L$, cooling time $t_{\rm cool}$, relative velocity $v_{\rm rel}$, and density contrast $\rho_{\rm cold}/\rho_{\rm hot}$ of the system. Entrainment is expected to be enhanced in environments with short $t_{\rm cool}$, large $v_{\rm rel}$, and large $\rho_{\rm cold}/\rho_{\rm hot}$. Using a large suite of three dimensional hydrodynamic simulations, we demonstrate that this fractal cooling layer model accurately captures the energetics and evolution of turbulent interfaces and can therefore be used as a foundation for understanding multiphase mixing with strong radiative cooling.
- [4] arXiv:2003.08392 [pdf, other]
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Title: Blazar origin of the UHECRs and perspectives for the detection of astrophysical source neutrinos at EeV energiesComments: 10 pages, 6 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We demonstrate that a population of blazars can describe the observed spectrum and composition of Ultra-High-Energy Cosmic Rays (UHECRs), and that the dominant contribution comes from low-luminosity BL Lacs. However, a sub-dominant contribution from high-luminosity blazars can lead to a substantial neutrino flux which will peak at EeV energies. We find that it is plausible that this neutrino flux from the sources outshines the cosmogenic neutrino flux produced during the propagation of UHECRs. This has profound implications for the high-energy (EeV) neutrino detection experiments: their main target may be source neutrinos, for which additional search strategies can be used, such as stacking searches, flare analyses, or multi-messenger follow-ups.
- [5] arXiv:2003.08393 [pdf, ps, other]
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Title: Observing the Effects of Galaxy Interactions on the Circumgalactic MediumComments: 6 pages and 3 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We continue our empirical study of the emission line flux originating in the cool ($T\sim10^4$ K) gas that populates the halos of galaxies and their environments. Specifically, we present results obtained for a sample of galaxy pairs with a range of projected separations, {\bf $10 < {S_p/\rm kpc} < 200$}, and mass ratios $<$ 1:5, intersected by 5,443 SDSS lines of sight at projected radii of 10 to 50 kpc from either or both of the two galaxies. We find significant enhancement in H$\alpha$ emission and a moderate enhancement in [N {\small II}]6583 emission for low mass pairs (mean stellar mass per galaxy, $\overline{\rm M}_*, <10^{10.4} {\rm M}_\odot$) relative to the results from a control sample. This enhanced H$\alpha$ emission comes almost entirely from sight lines located between the galaxies, consistent with a short-term, interaction-driven origin for the enhancement. We find no enhancement in H$\alpha$ emission, but significant enhancement in [N {\small II}]6583 emission for high mass ($\overline{\rm M}_* >10^{10.4}{\rm M}_\odot$) pairs. Furthermore, we find a dependence of the emission line properties on the galaxy pair mass ratio such that those with a mass ratio below 1:2.5 have enhanced [N {\small II}]6583 and those with a mass ratio between 1:2.5 and 1:5 do not. In all cases, departures from the control sample are only detected for close pairs ($S_p <$ 100 kpc). Attributing an elevated [N {\small II}]6583/H$\alpha$ ratio to shocks, we infer that shocks play a role in determining the CGM properties for close pairs that are among the more massive and have mass ratios closer to 1:1.
- [6] arXiv:2003.08395 [pdf, ps, other]
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Title: Over-constrained Models of Time Delay Lenses Redux: How the Angular Tail Wags the Radial DogAuthors: C. S. Kochanek (1) ((1) Department of Astronomy, The Ohio State University)Comments: sumbitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The two properties of the radial mass distribution of a gravitational lens that are well-constrained by Einstein rings are the Einstein radius R_E and xi2 = R_E alpha''(R_E)/(1-kappa_E), where alpha''(R_E) and kappa_E are the second derivative of the deflection profile and the convergence at R_E. However, if there is a tight mathematical relationship between the radial mass profile and the angular structure, as is true of ellipsoids, an Einstein ring can appear to strongly distinguish radial mass distributions with the same xi2. This problem is beautifully illustrated by the ellipsoidal models in Millon et al. (2019). When using Einstein rings to constrain the radial mass distribution, the angular structure of the models must contain all the degrees of freedom expected in nature (e.g., external shear, different ellipticities for the stars and the dark matter, modest deviations from elliptical structure, modest twists of the axes, modest ellipticity gradients, etc.) that work to decouple the radial and angular structure of the gravity. Models of Einstein rings with too few angular degrees of freedom will lead to strongly biased likelihood distinctions between radial mass distributions and very precise but inaccurate estimates of H0 based on gravitational lens time delays.
- [7] arXiv:2003.08399 [pdf, other]
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Title: Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization ArrayAuthors: Joshua S. Dillon, Max Lee, Zaki S. Ali, Aaron R. Parsons, Naomi Orosz, Chuneeta Devi Nunhokee, Paul La Plante, Adam P. Beardsley, Nicholas S. Kern, Zara Abdurashidova, James E. Aguirre, Paul Alexander, Yanga Balfour, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Phil Bull, Jacob Burba, Steve Carey, Chris L. Carilli, Carina Cheng, David R. DeBoer, Matt Dexter, Eloy de Lera Acedo, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R. Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J. Hazelton, Jacqueline N. Hewitt, Jack Hickish, Daniel C. Jacobs, Austin Julius, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Telalo Lekalake, David Lewis, et al. (31 additional authors not shown)Comments: 23 Pages, 19 FiguresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In 21 cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from bright astrophysical foregrounds. If not properly calibrated, each antenna element's complex gain can impart spectral structure on otherwise spectrally-smooth foregrounds, complicating that statistical separation. The Hydrogen Epoch of Reionization Array (HERA), an interferometer specialized for 21 cm cosmology and now under construction in South Africa, was designed to be largely calibrated using the self-consistency of repeated measurements of the same interferometric modes. This technique, known as redundant-baseline calibration resolves most of the internal degrees of freedom in the calibration problem. It assumes, however, on antenna elements with identical primary beams placed precisely on a redundant grid. In this work, we review the detailed implementation of the algorithms enabling redundant-baseline calibration and report results with HERA data. We quantify the effects of real-world non-redundancy and how they compare to the idealized scenario in which redundant measurements differ only in their noise realizations. Finally, we study how non-redundancy can produce spurious temporal structure in our calibration solutions---both in data and in simulations---and present strategies for mitigating that structure.
- [8] arXiv:2003.08402 [pdf, other]
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Title: Dark matter from primordial quantum informationSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
We suggest a general relation between the position of the cosmic microwave background temperature power spectrum peaks and the inflationary slow roll parameter $\epsilon$. This relation is based on interpreting the variable setting the position of the peaks as the quantum distance between the end of inflation and recombination. This distance is determined by the primordial cosmological Fisher information introduced in arXiv:2002.04294. The observational constraints set by cosmic microwave background temperature data lead to a very stringent prediction for the value of the tensor-to-scalar ratio: $r=0.01 \pm 0.002$. Future polarization data of the cosmic microwave background should be able to measure this signal and corroborate or discard our model.
- [9] arXiv:2003.08403 [pdf, ps, other]
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Title: Discovery of a thermonuclear Type I X-ray burst in infrared: new limits on the orbital period of 4U 1728-34Authors: F. M. Vincentelli, Y. Cavecchi, P. Casella, S. Migliari, D. Altamirano, T. Belloni, M. Diaz-TrigoComments: Accepted for publication in MNRAS Letters. 6 Pages, 4 FiguresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We report the detection of an infrared burst lagging a thermonuclear Type I X-ray burst from the accreting neutron star 4U 1728-34 (GX 354-0). Observations were performed simultaneously with XMM-Newton (0.7-12 keV), NuSTAR (3-79 keV) and HAWK-I@VLT (2.2$\mu$m). We measure a lag of $4.75 \pm 0.5$ s between the peaks of the emission in the two bands. Due to the length of the lag and the shape of the IR burst, we found that the most plausible cause for such a large delay is reprocessing of the Type I burst X-rays by the companion star. The inferred distance between the neutron star and the companion can be used to constrain the orbital period of the system, which we find to be larger than $\sim$ 66 minutes (or even $\gtrsim$ 2 hours, for a realistic inclination $< 75^\circ$). This is much larger than the current tentatively estimated period of $\sim 11$ minutes. We discuss the physical implications on the nature of the binary and conclude that most likely the companion of 4U 1728-34 is a helium star.
- [10] arXiv:2003.08404 [pdf, other]
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Title: GLaD: Gravitational Lensing and Dynamics, combined analysis to unveil properties of high-redshift galaxiesComments: 16 pages, 13 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Dynamical modelling of Integral-Field-Unit (IFU) stellar kinematics is a powerful tool to unveil the dynamical structure and mass build-up of galaxies in the local Universe, while gravitational lensing is nature's cosmic telescope to explore the properties of galaxies beyond the local Universe. We present a new approach which unifies dynamical modelling of galaxies with the magnification power of strong gravitational lensing, to reconstruct the structural and dynamical properties of high-redshift galaxies. By means of axisymmetric Jeans modelling, we create a dynamical model of the source galaxy, assuming a surface brightness and surface mass density profile. We then predict how the source's surface brightness and kinematics would look like when lensed by the foreground mass distribution and compare with the mock observed arcs of strong gravitational lensing systems. For demonstration purposes, we create and analyse mock data of the strong lensing system RX J1131-1231. By modelling both the lens and source, we recover the dynamical mass within the effective radius of strongly lensed high-redshift sources within 5% uncertainty, and we improve the constraints on the lens mass parameters by up to 50%. This machinery is particularly well suited for future observations from large segmented-mirror telescopes, such as the James Webb Space Telescope, that will yield high sensitivity and angular-resolution IFU data for studying distant and faint galaxies.
- [11] arXiv:2003.08410 [pdf, other]
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Title: Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017Comments: Accepted for publication in the Astrophysical Journal on the 11th of March, 2020. 14 pages, 3 figures, 2 tables. Pre-proofsSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The WD 1145+017 system shows irregular transit features that are consistent with the tidal disruption of differentiated asteroids with bulk densities $< 4$ g cm$^{-3}$ and bulk masses $\lesssim 10^{21}$ kg (Veras et al., 2017; arXiv:1610.06926). We use the open-source N-body code REBOUND (Rein and Liu, 2011; arXiv:1110.4876) to simulate this disruption with different internal structures: varying the core volume fraction, mantle/core density ratio, and the presence/absence of a thin low-density crust. We allow the rubble pile to partially disrupt and capture lightcurves at a specific point during the disruption at cadences comparable to those from ground-based photometry. As a proof-of-concept we show that varying these structural parameters have observationally distinguishable effects on the transit light curve as the asteroid is disrupted and compare the simulation-generated lightcurves to data from Gary et al., 2017 (arXiv:1608.00026). With the caveat that our simulations do not model the sublimation in detail or account for its effects on orbital evolution, we find that a low core fraction and low mantle/core density ratio asteroid is most consistent with the stable transit feature present for multiple weeks circa April 2016 (referred to as G6121 in Gary et al., 2017 (arXiv:1608.00026) and A1 in Hallakoun et al., 2017 (arXiv:1702.05483). Connecting tidal disruption simulations to photometry suggests characteristics for the interior structure and composition of an exoplanetary body, information that is only possible because we are observing the death of the planetary system in action. All-sky survey missions such as TESS and LSST will be able to detect other systems like WD 1145+017, creating a sample of subjects for a new subfield of planetary science: necroplanetology.
- [12] arXiv:2003.08431 [pdf, other]
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Title: Kepler Planets and MetallicityComments: Submitted to ApJSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Kepler planets (including super-Earths and sub-Neptunes) are likely formed before the gaseous proto-planetary disks have dissipated. Together with gas giants, we call these generation-I planets, to differentiate them from planets that form after disk dispersal (generation-II planets, e.g., terrestrial planets in the Solar system). If the metal content in these disks resembles that in the host stars, one naively expects Kepler planets to occur more frequently, and to be more massive, around metal-rich stars. Contrary to these expectations, we find that the radii of Kepler planets (a proxy for mass) are independent of host metallicity, and their occurrence rate rises only weakly with metallicity. The latter trend is further flattened when the influence of close binaries is accounted for. We interpret the first result as that the mass of a Kepler planet is regulated by a yet unknown process, as first suggested by \citet{Wu2019}. We explain the second result using a simple model, wherein the masses of proto-planetary disks have a much larger spread than the spread in stellar metallicity, and disks that contain more than $\sim 30$ Earth masses of total solid can form Kepler planets. Hosts for these planets, as a result, are only mildly more metal-rich than average. In contrast, the formation of a giant planet requires some $5$ times more solid. Their hosts, which also harbour Kepler planets, are significantly more metal-rich. This model also predicts that stars more metal-poor than half-solar should rarely host any gen-I planets.
- [13] arXiv:2003.08451 [pdf]
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Title: Bolometric Bond Albedo and Thermal Inertia Maps of MimasSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
We use data from Cassini's Composite Infrared Spectrometer CIRS to map Mimas' surface temperatures and its thermophysical properties. This provides a dramatic improvement on the work in Howett et al. (2011), where the values were determined at only two regions on Mimas (one inside, and another outside of the anomalous region). We use all spatially-resolved scans made by CIRS' focal plane 3 (FP3, 600 to 1100 cm-1) of Mimas' surface, which are largely daytime observations but do include one nighttime one. The resulting temperature maps confirm the presence and location of Mimas' previously discovered thermally anomalous region. No other thermally anomalous regions were discovered, although we note that the surface coverage is incomplete on Mimas' leading and anti-Saturn hemisphere. The thermal inertia map confirms that the anomalous region has a notably higher thermal inertia than its surroundings: 98 +/- 42 J m-2 K-1 s-1/2 inside of the anomaly, compared to 34 +/- 32 J m-2 K-1 s-1/2 outside. The albedo inside and outside of the anomalous region agrees within their uncertainty: 0.45+/-0.08 inside compared to 0.41 +/- 0.07 outside the anomaly. Interestingly the albedo appears brighter inside the anomaly region, which may not be surprising given this region does appear brighter at some UV wavelengths (0.338 microns, see Schenk et al., 2011). However, this result should be treated with caution because, as previously stated, statistically the albedo of these two regions is the same when their uncertainties are considered. These thermal inertia and albedo values determined here are consistent with those found by Howett et al. (2011), who determined the thermal inertia inside the anomaly to be 66 +/- 23 J m-2 K-1 s-1/2 and less than 16 J m-2 K-1 s-1/2 outside, with albedos that varied from 0.49 to 0.70.
- [14] arXiv:2003.08464 [pdf, other]
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Title: LARgE Survey -- III. Environments of Ultra-Massive Passive Galaxies at Cosmic Noon: BCG progenitors growing through mergersAuthors: Marcin Sawicki, Liz Arcila-Osejo, Anneya Golob, Thibaud Moutard, Stephane Arnouts, Gurpreet Kaur CheemaComments: accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We study the environments of a sample of 61 extremely rare z~1.6 Ultra-Massive Passively Evolving Galaxies (UMPEGs: stellar masses M_stars >10^11.5 M_sun) which -- based on clustering analysis presented in Cheema et al. (2020) -- appear to be associated with very massive (M_halo ~ 10^14.1 h^-1 M_sun) dark matter halos that are likely to be the progenitors of z~0 massive (Coma- and Virgo-like) galaxy clusters. We find that UMPEGs on average have fewer than one satellite galaxy with mass ratio M_sat : M_UMPEG >~ 1:5 (i.e., M_sat >~ 10^10.8 M_sun) within 0.5 Mpc; the large mass gap that we observe between the typical UMPEG and its most massive satellite implies that the z~1.6 UMPEGs assembled through major mergers. Using observed satellite counts with merger timescales from the literature, we estimate the growth rate due to mergers with mass ratio of >~ 1:4 to be ~13% Gyr^-1 (with a ~2x systematic uncertainty). This relatively low growth rate is unlikely to significantly affect the shape of the massive end of the stellar mass function, whose evolution must instead be driven by the quenching of new cohorts of ultra-massive star-forming galaxies. However, this growth rate is high enough that, if sustained to z~0, the typical z~1.6 M_UMPEG=10^11.6 M_sun UMPEG can grow into a M_stars~10^12 M_sun brightest cluster galaxy (BCG) of a present-day massive galaxy cluster. Our observations favour a scenario in which our UMPEGs are main-branch progenitors of some of the present-day BCGs that have first assembled through major mergers at high redshifts and grown further through (likely minor) merging at later times.
- [15] arXiv:2003.08475 [pdf, ps, other]
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Title: CLASH-VLT: a full dynamical reconstruction of the mass profile of Abell S1063 from 1 kpc out to the virial radiusAuthors: B. Sartoris, A. Biviano, P. Rosati, A. Mercurio, C.Grillo, S. Ettori, M. Nonino, K. Umetsu, P. Bergamini, G.B.Caminha, M. GirardiComments: Accepted on Astronomy and AstrophysicsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Context: The shape of the mass density profiles of cosmological halos informs us of the nature of DM and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition to predictions derived from numerical simulations of CDM. Aims: We determine the inner slope of the DM density profile of a massive cluster of galaxies, Abell S1063 (RXC J2248.7$-$4431) at $z=0.35$, with a dynamical analysis based on an extensive spectroscopic campaign carried out with the VIMOS and MUSE spectrographs at the ESO VLT. This new data set provides an unprecedented sample of 1234 spectroscopic members, 104 of which are located in the cluster core (R < 200 kpc), extracted from the MUSE integral field spectroscopy. The latter also allows the stellar velocity dispersion profile of the brightest cluster galaxy (BCG) to be measured out to 40 kpc. Methods: We used an upgraded version of the MAMPOSSt technique to perform a joint maximum likelihood fit to the velocity dispersion profile of the BCG and to the velocity distribution of cluster member galaxies over a radial range from 1 kpc to the virial radius (~ 2.7 Mpc). Results: We find a value of $\gamma_{DM} =0.99 \pm 0.04$ for the inner logarithmic slope of the DM density profile after marginalizing over all the other parameters. The newly determined dynamical mass profile is found to be in excellent agreement with the mass density profiles obtained from the independent X-ray hydrostatic analysis based on deep Chandra data, as well as the strong and weak lensing analyses. Our value of \gamma_{DM} is in very good agreement with predictions from cosmological CDM simulations. We will extend our analysis to more clusters in future works. If confirmed on a larger cluster sample, our result makes this DM model more appealing than alternative models.
- [16] arXiv:2003.08509 [pdf, ps, other]
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Title: A Compact X-Ray Emitting Binary in Likely Association with 4FGL J0935.3+0901Authors: Zhongxiang Wang (1), Yi Xing (1), Jujia Zhang (2 and 3), Konstantina Boutsia (4), Gege Wang (1), Jithesh V. (5), Kevin B. Burdge (6), Michael W. Coughlin (7), Dmitry A. Duev (7), S. R. Kulkarni (7 and 6), Reed Riddle (6), Eugene Serabyn (8) ((1) Shanghai Astronomical Observatory China, (2) Yunnan Observatories China, (3) Key Laboratory for the Structure and Evolution of Celestial Objects China, (4) Las Campanas Observatory Chile, (5) Inter-University Centre for Astronomy and Astrophysics India, (6) Caltech Optical Observatories USA, (7) Division of Physics Math and Astronomy California Institute of Technology USA, (8) Jet Propulsion Laboratory California Institute of Technology USA)Comments: 9 pages, 5 figures, 1 table, to appear in MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
4FGL J0935.3+0901 is a gamma-ray source detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope. We have conducted detailed analysis of the LAT data for this source and multi-wavelength studies of the source field. Its gamma-ray emission can be described with a power law ($\Gamma=2.0\pm0.2$) with an exponential cutoff ($E_c=2.9\pm1.6$ GeV), while the flux shows significant long-term variations. From analysis of archival Neil Gehrels Swift X-ray Telescope data, we find only one X-ray source in the LAT's 2$\sigma$ error region. Within a 3.7" radius error circle of the X-ray source, there is only one optical object down to $r'\sim$23 mag. Time-resolved photometry of the optical object indicates a likely 2.5~hr periodic modulation, while its spectrum shows double-peaked hydrogen and helium emission lines (similar to those seen in accretion discs in low-mass X-ray binaries). Combining these results, we conclude that we have discovered a compact X-ray emitting binary in likely association with 4FGL J0935.3+0901, i.e., a millisecond pulsar (MSP) binary. We discuss the implication of the optical spectral features: this binary could be a transitional MSP system at a sub-luminous disc state, although the other possibility, the binary in a rotation-powered state showing the optical emission lines due to intrabinary interaction processes, can not be excluded. Further observational studies will help determine detailed properties of this candidate MSP binary and thus clarify its current state.
- [17] arXiv:2003.08510 [pdf, other]
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Title: An improved analysis framework for axion dark matter searchesAuthors: D. A. Palken, B. M. Brubaker, M. Malnou, S. Al Kenany, K. M. Backes, S. B. Cahn, Y. V. Gurevich, S. K. Lamoreaux, S. M. Lewis, R. H. Maruyama, N. M. Rapidis, J. R. Root, M. Simanovskaia, T. M. Shokair, Sukhman Singh, D. H. Speller, I. Urdinaran, K. van Bibber, L. Zhong, K. W. LehnertComments: 22 pages, 5 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)
In experiments searching for axionic dark matter, the use of the standard threshold-based data analysis discards valuable information. We present a Bayesian analysis framework that builds on an existing processing protocol to extract more information from the data of coherent axion detectors such as operating haloscopes. The analysis avoids logical subtleties that accompany the standard analysis framework and enables greater experimental flexibility on future data runs. Performing this analysis on the existing data from the HAYSTAC experiment, we find improved constraints on the axion-photon coupling $g_\gamma$ while also identifying the most promising regions of parameter space within the $23.15$--$24.0$ $\mu$eV mass range. A comparison with the standard threshold analysis suggests a $36\%$ improvement in scan rate from our analysis, demonstrating the utility of this framework for future axion haloscope analyses.
- [18] arXiv:2003.08538 [pdf, other]
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Title: The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transitionAuthors: L. J. Wang, M. Y. Ge, J. S. Wang, S. S. Weng, H. Tong, L. L. Yan, S. N. Zhang, Z. G. Dai, L. M. SongComments: 7 pages, 2 figures, revised after referee's reportSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
In Dec. 2011 PSR B0540-69 experienced a spin-down rate transition (SRT), after which the spin-down power of the pulsar enhanced ~36%. About 1000 days after the SRT, the X-ray luminosity of the associated pulsar wind nebula (PWN) was found to brighten by 32+/-8%. After the SRT, the braking index n of PSR B0540-69 changes from n=2.12 to n=0.03 and then keeps this value for about five years before rising to n=0.9 in the following years. We find that most of the current models have difficulties in explaining the measured braking index. While one exceptive model of the braking index evolution is the increasing dipole magnetic field of PSR B0540-69. We suggest that the field increase may result from some instabilities within the pulsar core that enhance the poloidal component at the price of toroidal component of the magnetic field. The increasing dipole magnetic field will result in the X-ray brightening of the PWN. We fit the PWN X-ray light curve by two models: one assumes a constant magnetic field within the PWN during the brightening and the other assumes an enhanced magnetic field proportional to the energy density of the PWN. It appears that the two models fit the data equally well, although the later model seems to fit the data a bit better. This provides marginal observational evidence that magnetic field in the PWN is generated by the termination shock. Future high-quality and high-cadence data are required to draw a solid conclusion.
- [19] arXiv:2003.08547 [pdf, ps, other]
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Title: Effects of rotational disruption on the evolution of grain size distribution in galaxiesComments: 13 pages, 11 figures, Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Interstellar dust grains can be spun up by radiative torques, and the resulting centrifugal force may be strong enough to disrupt large dust grains. We examine the effect of this rotational disruption on the evolution of grain size distribution in galaxies. To this goal, we modify our previous model by assuming that rotational disruption is the major small-grain production mechanism. We find that rotational disruption can have a large influence on the evolution of grain size distribution in the following two aspects especially for composites and grain mantles (with tensile strength $\sim 10^7$ erg cm$^{-3}$). First, because of the short time-scale of rotational disruption, the small-grain production occurs even in the early phase of galaxy evolution. Therefore, even though stars produce large grains, the abundance of small grains can be large enough to steepen the extinction curve. Secondly, rotational disruption is important in determining the maximum grain radius, which regulates the steepness of the extinction curve. For compact grains with tensile strength $\gtrsim 10^9$ erg cm$^{-3}$, the size evolution is significantly affected by rotational disruption only if the radiation field is as strong as (or the dust temperature is as high as) expected for starburst galaxies. For compact grains, rotational disruption predicts that the maximum grain radius becomes less than 0.2 $\mu$m for galaxies with a dust temperature $\gtrsim 50$ K.
- [20] arXiv:2003.08552 [pdf, other]
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Title: The Impact of Realistic Foreground and Instrument Models on 21cm Epoch of Reionization ExperimentsAuthors: Ainulnabilah Nasirudin, Steven Murray, Cathryn Trott, Bradley Greig, Ronniy Joseph, Chris PowerSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Predictions for the ability of 21-cm interferometric experiments to discriminate Epoch of Reionization (EoR) signal models are typically limited by the simplicity of data models, whereby foreground signals and characteristics of the instrument are often simplified or neglected.To move towards more realistic scenarios, we explore the effects of applying more realistic foreground and instrument models to the 21cm signal, and the ability to estimate astrophysical parameters with these additional complexities. We use a highly-optimized version of \textsc{21cmFAST}, integrated into \textsc{21cmMC}, to generate lightcones of the brightness temperature fluctuation for Bayesian parameter estimation. We include a statistical point-source foreground model and an instrument model based on the Murchison Widefield Array (MWA) scaled in observation time to have an effective sensitivity similar to the future Square Kilometre Array (SKA). We also extend the current likelihood prescription to account for the presence of beam convolution and foregrounds, the 2-Dimensional Power Spectrum (PS), and the correlation of PS modes. We use frequency bands between 150 and 180 MHz to constrain the ionizing efficiency ($\zeta$), the minimum virial temperature of halos ($T_{\mathrm{vir}}$), the soft X-ray emissivity per unit Star Formation Rate (SFR) ($L_X/SFR$ ), and the X-ray energy threshold ($E_0$). We find that the inclusion of realistic foregrounds and instrumental components biases the parameter constraints due to unaccounted for cross-power between the EoR signal, foregrounds and thermal noise. This causes estimates of $\zeta$ to be biased by up to $5\sigma$ but the estimates of $T_{vir}$, L$_X$/SFR and E$_0$ remain unaffected and are all within $1\sigma$.
- [21] arXiv:2003.08564 [pdf, other]
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Title: Cosmic Evolution of Stellar-mass Black Hole Merger Rate in Active Galactic NucleiComments: 6 pages, 2 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Binary black hole mergers encode information about their environment and the astrophysical processes that led to their formation. Measuring the redshift dependence of their merger rate will help probe the formation and evolution of galaxies and the evolution of the star formation rate. Here we compute the cosmic evolution of the merger rate for stellar-mass binaries in the disks of Active Galactic Nuclei (AGNs). We focus on recent evolution out to redshift $z=2$, covering the accessible range of current Earth-based gravitational-wave observatories. On this scale, the AGN population density is the main contributor to redshift-dependence. We find that the AGN-assisted merger rate does not meaningfully evolve with redshift, differentiating this channel from field binaries and some other dynamical formation scenarios.
- [22] arXiv:2003.08578 [pdf, other]
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Title: SDSS-IV MaNGA: Bayesian analysis of the star formation history of low-mass galaxies in the local UniverseComments: 20 pages, 20 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We measure the star formation histories (SFH) of a sample of low-mass galaxies with $M_\ast<10^9M_\odot$ from the SDSS-IV MaNGA survey. The large number of IFU spectra for each galaxy are either combined to reach a high signal to noise ratio or used to investigate spatial variations. We use Bayesian inferences based on full spectrum fitting. Our analysis based on Bayesian evidence ratio indicates a strong preference for a model that allows the presence of an old stellar population, and that an improper model for the SFH can significantly underestimate the old population in these galaxies. The addition of NIR photometry to the constraining data can further distinguish between different SFH model families and significantly tighten the constraints on the mass fraction in the old population. On average more than half of the stellar mass in present-day low-mass galaxies formed 8 Gyrs ago, while about 30\% within the past 4 Gyrs. Satellite galaxies on average have formed their stellar mass earlier than central galaxies, and stars in the outer regions of galaxy are younger than those in the central part. Our results suggest that most of the low-mass galaxies have an early episode of active star formation that produces a large fraction of their present stellar mass.
- [23] arXiv:2003.08586 [pdf]
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Title: Pulsar Timing Observations with Haoping Radio TelescopeAuthors: Jintao Luo, Yuping Gao, Tinggao Yang, Chengshi Zhao, Minglei Tong, Yongnan Rao, Yifeng Li, Bian Li, Xingzhi Zhu, Haihua Qiao, Xiaochun LuComments: 10 pages, 8 figures, accepted for publication in RAA (Res. Astron. Astrophys.)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We report pulsar timing observations carried out in L-band with NTSC's 40-meter Haoping Radio Telescope (HRT), which was constructed in 2014. The observations were carried out using the pulsar machine we developed. Timing observations toward millisecond pulsar J0437-4715 obtains a timing residual (r.m.s) of 397ns in the time span of 284 days. And our observations successfully detected Crab pulsar's glitch that happened on July 23rd, 2019.
- [24] arXiv:2003.08587 [pdf, other]
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Title: Local Molecular Gas toward the Aquila Rift RegionAuthors: Yang Su, Ji Yang, Qing-zeng Yan, Yan Gong, Zhiwei Chen, Shaobo Zhang, Yan Sun, Miaomiao Zhang, Xuepeng Chen, Xin Zhou, Min Wang, Hongchi Wang, Ye Xu, Zhibo JiangComments: 25 figures, 1 table, Accepted by ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We present the results of a ~250 square degrees CO mapping (+26d<l<+50d and -5d<b<+5d) toward the Aquila Rift region at a spatial resolution of ~50" and a grid spacing of 30". The high dynamic range CO maps with a spectral resolution of ~0.2km/s display highly structured molecular cloud (MC) morphologies with valuable velocity information, revealing complex spatial and dynamical features of the local molecular gas. In combination with the MWISP CO data and the Gaia DR2, distances of the main MC structures in the local ISM are well determined toward the Aquila Rift. We find that the total MC mass within 1 kpc is about >4.1x10^5 Msun in the whole region. In fact, the mass of the molecular gas is dominated by the W40 giant molecular cloud (GMC) at ~474 pc (~1.4x10^5 Msun) and the GMC complex G036.0+01.0 at ~560-670 pc (~2.0x10^5 Msun), while the MCs at ~220-260pc have gas mass of 10^2-10^3 Msun. Interestingly, a ~80pc long filamentary MC G044.0-02.5 at a distance of ~404 pc shows a systematic velocity gradient along and perpendicular to the major axis of the filament. The HI gas with the enhanced emission has the similar spatial morphologies and velocity features compared to the corresponding CO structure, indicating that the large-scale converging HI flows is probably responsible for the formation of the MC. Meanwhile, the long filamentary MC consists of many sub-filaments with the lengths ranging from ~0.5 pc to several pc, as well as prevalent networks of filaments in other large-scale local MCs.
- [25] arXiv:2003.08601 [pdf, ps, other]
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Title: Time Variations in the Flux Density of Sgr A* at 230 GHz Detected with ALMAComments: 8 pages, 3 figures, 1 table, accepted for publication in ApJLSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz band flux of Sgr A* have been found with the Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 observations. Measuring the flux density of Sgr A* in 1 min snapshots at 217.5, 219.5, and 234.0 GHz, we obtained light curves for ten 70 min periods. The light curves show variations at a few tens of minutes and hourly scales. The shorter timescale is similar to the orbital period of the innermost stable circular orbit around a $4\times 10^{6}$ $M_{\odot}$ black hole, suggesting that the variation originates from the immediate vicinity of Sgr A*. We also detected no time lag between 217.5 and 234.0 GHz and a dependence of the spectral index on the flux density.
- [26] arXiv:2003.08618 [pdf, other]
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Title: On neural architectures for astronomical time-series classificationComments: Submitted to ApJSSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Despite the utility of neural networks (NNs) for astronomical time-series classification, the proliferation of learning architectures applied to diverse datasets has thus far hampered a direct intercomparison of different approaches. Here we perform the first comprehensive study of variants of NN-based learning and inference for astronomical time-series, aiming to provide the community with an overview on relative performance and, hopefully, a set of best-in-class choices for practical implementations. In both supervised and self-supervised contexts, we study the effects of different time-series-compatible layer choices, namely the dilated temporal convolutional neural network (dTCNs), Long-Short Term Memory (LSTM) NNs, Gated Recurrent Units (GRUs) and temporal convolutional NNs (tCNNs). We also study the efficacy and performance of encoder-decoder (i.e., autoencoder) networks compared to direct classification networks, different pathways to include auxiliary (non-time-series) metadata, and different approaches to incorporate multi-passband data (i.e., multiple time-series per source). Performance---applied to a sample of 17,604 variable stars from the MACHO survey across 10 imbalanced classes---is measured in training convergence time, classification accuracy, reconstruction error, and generated latent variables. We find that networks with Recurrent NN (RNNs) generally outperform dTCNs and, in many scenarios, yield to similar accuracy as tCNNs. In learning time and memory requirements, convolution-based layers are more performant. We conclude by discussing the advantages and limitations of deep architectures for variable star classification, with a particular eye towards next-generation surveys such as LSST, WFIRST and ZTF2.
- [27] arXiv:2003.08630 [pdf, other]
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Title: The Boltzmann-radiation-hydrodynamics Simulations of the Core-collapse Supernova with the Different Equations of State: the Role of Nuclear Composition and the Behavior of NeutrinosAuthors: Akira Harada, Hiroki Nagakura, Wakana Iwakami, Hirotada Okawa, Shun Furusawa, Kohsuke Sumiyoshi, Hideo Matsufuru, Shoichi YamadaComments: 26 pages, 20 figures, 1 explosion, submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
Using the Boltzmann-radiation-hydrodynamics code which solves the Boltzmann equation for the neutrino transport, we present the results of the simulations with the nuclear equations of state (EOSs) of Lattimer-Swesty (LS) and Furusawa-Shen (FS). We extend the simulation time of the LS model and conducted thorough investigations, though the previous paper reported some of the results briefly. Only the LS model shows the shock revival. This seems to originate from the nuclear composition: the different nuclear composition results in the different energy loss by the photodissociation and hence the different strength of the prompt convection and the later neutrino-driven convection. The proto-neutron star seen in the FS model is more compact than that in the LS model since the existence of multi-nuclear species softens the EOS. For the behavior of neutrinos, we examined the flux and the Eddington tensor of neutrinos. In the optically thick region, the diffusion of neutrinos and the dragging by the matter motion determine the flux. In the optically thin region, the free-streaming determines it. The Eddington tensor is compared with that obtained from the M1-closure relation. The M1-closure scheme overestimates the contribution from the velocity-dependent terms in the semi-transparent region.
- [28] arXiv:2003.08631 [pdf, other]
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Title: Dust and gas content of high-redshift galaxies hosting obscured AGN in the CDF-SAuthors: Q. D'Amato, R. Gilli, C. Vignali, M. Massardi, F. Pozzi, G. Zamorani, C. Circosta, F. Vito, J. Fritz, G. Cresci, V. Casasola, F. Calura, A. Feltre, V. Manieri, D. Rigopoulou, P. Tozzi, C. NormanComments: 15 pages, 6 figures, 7 tables. Accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
Obscured AGN represent a significant fraction of the entire AGN population, especially at high redshift (~70% at z=3--5). They are often characterized by the presence of large gas and dust reservoirs that are thought to sustain and possibly obscure vigorous star formation processes that make these objects shine at far-IR and sub-mm wavelengths. We exploit ALMA Cycle 4 observations of the continuum (~2.1mm) and high-J CO emission of a sample of six X-ray selected SMGs hosting an obscured AGN at z_spec>2.5 in the 7 Ms CDF-S. We measured the masses and sizes of the dust and molecular gas and we derived the gas density and column density on the basis of a uniform sphere geometry. Finally, we compared the measured column densities with those derived from the Chandra X-ray spectra. We detected both the continuum and line emission for three sources for which we measured both the flux density and size. For the undetected sources, we derived an upper limit on the flux density. We found that the detected galaxies are rich in gas and dust (molecular gas mass in the range <0.5 - 2.7 x 10^10 M_sun for {\alpha}_CO=0.8 and up to ~2 x 10^11~M_sun for {\alpha}_CO=6.5, and dust mass <0.9 - 4.9 x 10^8 M_sun) and compact (gas major axis 2.1-3.0 kpc, dust major axis 1.4-2.7 kpc). The column densities associated with the ISM are on the order of 10^(23-24) cm-2, which is comparable with those derived from the X-ray spectra. For the detected sources we also derived dynamical masses in the range 0.8 - 3.7 x 10^10 M_sun. We conclude that the ISM of high redshift galaxies can substantially contribute to nuclear obscuration up to the Compton-thick (>10^24 cm-2) regime. In addition, we found that all the detected sources show a velocity gradient reminding one rotating system, even though two of them show peculiar features in their morphology that can be associated with a chaotic, possibly merging, structure.
- [29] arXiv:2003.08639 [pdf, other]
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Title: Fake massive black holes in the milli-Hertz gravitational-wave bandComments: 8 pages, 6 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
In gravitational wave (GW) astronomy accurate measurement of the source parameters, such as mass, relies on accurate waveform templates. Currently, the templates are developed assuming that the source, such as a binary black hole (BBH), is residing in a vacuum. However, astrophysical models predict that BBHs could form in gaseous environments, such as common envelops, stellar cores, and accretion disks of active galactic nuclei. Here we revisit the impact of gas on the GW waveforms of stellar-mass BBHs with a focus on the early inspiral phase when the GW frequency is around milli-Hertz. We show that for these BBHs, gas friction could dominate the dynamical evolution and hence duplicate chirp signals. The relevant hydrodynamical timescale, $\tau_{\rm gas}$, could be much shorter than the GW radiation timescale, $\tau_{\rm gw}$, in the above astrophysical scenarios. As a result, the observable chirp mass is higher than the real one by a factor of $(1+\tau_{\rm gw}/\tau_{\rm gas})^{3/5}$ if the gas effect is ignored in the data analysis. Such an error also results in an overestimation of the source distance by a factor of $(1+\tau_{\rm gw}/\tau_{\rm gas})$. By performing matched-filtering analysis in the milli-Hertz band, we prove that the gas-dominated signals are practically indistinguishable from the chirp signals of those more massive BBHs residing in a vacuum environment. Such fake massive objects in the milli-Hertz band, if not appropriately accounted for in the future, may alter our understanding of the formation, evolution, and detection of BBHs.
- [30] arXiv:2003.08641 [pdf, other]
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Title: Tracking the state transitions in changing-look active galactic nuclei through their polarized-light echoesComments: 13 pages, 7 figures, accepted for publication in Astronomy & AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Context: Variations in the mass accretion rate appear to be responsible for the rapid transitions in spectral type that are observed in increasingly more active galactic nuclei (AGNs). These objects are now labeled "changing-look" AGNs and are key objects for understanding the physics of accretion onto supermassive black holes. Aims: We aim to complement the analysis and interpretation of changing-look AGNs by modeling the polarization variations that can be observed, in particular, polarized-light echoes. Methods: We built a complex and representative model of an AGN and its host galaxy and ran radiative transfer simulations to obtain realistic time-dependent polarization signatures of changing-look objects. Based on actual data, we allowed the system to become several times fainter or brighter within a few years, assuming a rapid change in accretion rate. Results: We obtain time-dependent polarization signatures of distant high-luminosity (quasars) and nearby low-luminosity (Seyferts) changing-look AGNs for a representative set of inclinations. We predict the evolution of the continuum polarization for future polarimetric campaigns with the goal to better understand the physics at work in these objects. We also investigate highly inclined AGNs that experience strong accretion rate variations without appearing to change state. We apply our modeling to Mrk 1018, the best-documented case of a changing-look AGN, and predict a variation in its polarization after the recent dimming of its continuum.
- [31] arXiv:2003.08642 [pdf, other]
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Title: Filling the uv-gaps of the current VLBI network in AfricaComments: 10 pagesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
In the African continent, South Africa has world-class astronomical facilities for advanced radio astronomy research. With the advent of the Square Kilometre Array project in South Africa (SA SKA), six countries in Africa (SA SKA partner countries) have joined South Africa to contribute towards the African Very Long Baseline Interferometry (VLBI) Networks (AVN). Each of the AVN countries will soon have a single-dish radio telescope that will be part of the AVN, the European VLBI Network, and the global VLBI network. The SKA and the AVN will enable very high sensitivity VLBI in the southern hemisphere. In the current AVN network, there is a gap in coverage in the central African region. This work analyses the scientific impact if new antennas were to be built or old telecommunication facilities were to be converted to radio telescopes in each of the six countries in central Africa i.e. Cameroon, Gabon, Congo, Equatorial Guinea, Chad, Central African Republic. The work also discusses some economical and skills transfer impacts of having a radio interferometer in this area of Africa.
- [32] arXiv:2003.08658 [pdf, other]
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Title: ALMA 0.88 mm Survey of Disks around Planetary-mass CompanionsAuthors: Ya-Lin Wu, Brendan P. Bowler, Patrick D. Sheehan, Sean M. Andrews, Gregory J. Herczeg, Adam L. Kraus, Luca Ricci, David J. Wilner, Zhaohuan ZhuComments: Accepted for publication in AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Characterizing the physical properties and compositions of circumplanetary disks can provide important insights into the formation of giant planets and satellites. We report ALMA 0.88 mm (Band 7) continuum observations of six planetary-mass (10-20 $M_{\rm Jup}$) companions: CT Cha b, 1RXS 1609 b, ROXs 12 b, ROXs 42B b, DH Tau b, and FU Tau b. No continuum sources are detected at the locations of the companions down to 3$\sigma$ limits of 120-210 $\mu$Jy. Given these non-detections, it is not clear whether disks around planetary-mass companions indeed follow the disk flux-host mass trend in the stellar regime. The faint radio brightness of these companion disks may result from a combination of fast radial drift and a lack of dust traps. Alternatively, as disks in binary systems are known to have significantly lower millimeter fluxes due to tidal interactions, these companion disks may instead follow the relationship of moderate-separation binary stars. This scenario can be tested with sensitive continuum imaging at rms levels of $\lesssim$10 $\mu$Jy.
- [33] arXiv:2003.08660 [pdf, other]
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Title: On the growth rate of plasmoid chains during nonlinear viscoresistive evolution of the tilt instabilityAuthors: Hubert BatyComments: arXiv admin note: substantial text overlap with arXiv:2001.07036Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Theory (hep-th); Plasma Physics (physics.plasm-ph)
We investigate by means of two-dimensional incompressible magnetohydrodynamic (MHD) numerical simulations, the onset phase of the fast collisional magnetic reconnection regime that is supported by the formation of plasmoid chains when the Lundquist number S exceeds a critical value. The present study extends previous results obtained at magnetic Prandtl number Pm = 1 (Baty 2020) to a range of different Pm values. We use FINMHD code where a set of reduced visco-resistive MHD equations is employed to form two quasi-singular current layers as a consequence of the tilt instability. The results reinforce the conclusion that, a phase of sudden super-Alfvenic growth (when Pm is not too high) of plasmoid chains is obtained, following a previous quiescent phase during current sheet formation on a slower Alfvenic time scale. We compare our results with predictions from the general theory of the plasmoid instability. We also discuss the importance of this onset phase to reach the ensuing stochastic time-dependent reconnection regime, where a fast time-averaged rate independent of S is obtained. Finally, we briefly discuss the relevance of our results to explain the flaring activity in solar corona and internal disruptions in tokamaks.
- [34] arXiv:2003.08676 [pdf]
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Title: Nearly Century-scale Variation of the Sun's RadiusJournal-ref: K. M. Hiremath et al 2020 ApJ 891 151Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
The Kodaikanal Archive Program (India) is now available to the scientific community in digital form as daily digitized solar white light pictures, from 1923 to 2011. We present here the solar radius data, obtained after a painstaking effort to remove all effects that contribute to the error in their measurements (limb darkening, distortion of the objective lens, refraction, other instrumental effects, etc.). These data were analyzed to reveal any significant periodic variations, after applying a multi-taper method with red noise approximation and the Morlet wavelet transform analysis. After removing obvious periodic variations (such as solar rotation and Earth annual rotation), we found a possible cycle variation at 11.4 yr, quasi biennial oscillations at 1.5 and 3.8 yr, and Rieger-type periodicity at ~159, 91, and 63 days. Another ~7.5 yr periodicity (as a mean) resulting from two other main periodicities detected at 6.3-7.8 yr can be identified as an atmospheric component. The detrending data show, over a mean radius of 959".7 +/- 0".7, a residual of less than ~(-)1 mas over the time period of analysis: if not spurious, this estimate indicates a faint decline, but probably confirms more the constancy of the solar diameter during the considered ranging time, within instrumental and methodological limits. The Kodaikanal long quality observations contribute to international efforts to bring past solar data measurements to the community to further explore issues, for instance, those of the luminosity/radius properties that could be used to pinpoint the "seat of the solar cycle."
- [35] arXiv:2003.08688 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame: I. The Most Energetic Outflows in the Universe and Other DiscoveriesComments: 11 pages, 4 figures, 2 tablesJournal-ref: ApJS 247 (2020) 37Subjects: Astrophysics of Galaxies (astro-ph.GA)
The Hubble Space Telescope/Cosmic Origins Spectrograph (COS) has opened a new discovery space for studying quasar absorption outflows and their contribution to AGN feedback. Specifically, COS provides high-quality far-ultraviolet (FUV) spectra covering the diagnostic-rich 500-1050 Angstrom rest frame (hereafter, EUV500) of medium redshift objects. The quality and quantity of EUV500 diagnostic troughs allow us to probe the very high-ionization phase, which carries 90% or more of the outflowing material, as well as to determine the distance of most outflows from the central source ($R$). The first objective is impossible to achieve with ground-based spectra, and $R$ can be measured in only $\sim$1% of them. Here, we summarize the main results of the first dedicated survey of such outflows, including the following:
1) Measurements of the three most energetic outflows to date, which can be the main agents for AGN feedback processes in the environments of the host galaxies.
2) All the outflows have a very high-ionization component, similar to the one found in warm absorbers, which carries most of the outflow's kinetic luminosity. This finding suggests that all the high-ionization outflows observed from the ground also have a similar undetected very high-ionization component.
3) Of the 13 studied EUV500 outflows, 9 have $100<R<2000$ parsecs, 2 have $5<R<20$ parsecs, 1 has $0.05<R<50$ parsecs, and in 1 case, $R$ cannot be determined.
4) One of the outflows has the largest velocity shift (1550 km s$^{-1}$) and acceleration (1.5 cm s$^{-2}$) measured to date. This outflow is physically similar to the fast X-ray outflow detected in quasar PG 1211+143. - [36] arXiv:2003.08689 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500 -- 1050 Å Rest Frame: II The Most Energetic Quasar Outflow Measured to DateComments: 18 pages, 12 figures, published in ApJSJournal-ref: 2020ApJS 247 38Subjects: Astrophysics of Galaxies (astro-ph.GA)
We present a study of the BAL outflows seen in quasar SDSS J1042+1646 (z = 0.978) in the rest-frame 500 -- 1050 $\r{A}$ (EUV500) region. The results are based on the analysis of recent Hubble Space Telescope/Cosmic Origins Spectrograph observations. Five outflow systems are identified, where in total they include $\sim$70 outflow troughs from ionic transitions. These include the first non-solar detections from transitions of O V*, Ne V*, Ar VI, Ca VI, Ca VII, and Ca VIII. The appearance of very high-ionization species (e.g., Ne VIII, Na IX, and Mg X) in all outflows necessitates at least two-ionization phases for the observed outflows. We develop an interactive Synthetic Spectral Simulation method to fit the multitude of observed troughs. Detections of density sensitive troughs (e.g., S IV* $\lambda$ 657.32 $\r{A}$ and the O V* multiplet) allow us to determine the distance of the outflows ($R$) as well as their energetics. Two of the outflows are at $R$ $\simeq$ 800 pc and one is at $R$ $\simeq$ 15 pc. One of the outflows has the highest kinetic luminosity on record ($\dot{E_{k}}$ $ = 5\times 10^{46}$ erg s$^{-1}$), which is 20% of its Eddington luminosity. Such a large ratio suggests that this outflow can provide the energy needed for active galactic nucleus feedback mechanisms.
- [37] arXiv:2003.08690 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame: III. Four Similar Outflows in 2MASS J1051+1247 with Enough Energy to be Major Contributors to AGN FeedbackComments: 11 pages, 3 figures, 4 tablesJournal-ref: ApJS 247 (2020) 39Subjects: Astrophysics of Galaxies (astro-ph.GA)
We detect four very energetic outflows in the Hubble Space Telescope/Cosmic Origin Spectrograph spectra of quasar 2MASS J1051+1247 with a combined kinetic luminosity ($\dot{E_k}$) of 10$^{46}$ erg s$^{-1}$. Remarkable similarities are seen in these outflows: velocity centroids between 4900 and 5700 km s$^{-1}$, distances from the central source ($R$) of a few hundred parsecs that are all consistent within the errors, and an $\dot{E_k}$ within a factor of two for all outflows. Hence, a common origin for the outflows is probable. Most of the outflowing mass resides in a very high-ionization phase evident by troughs from Ne VIII, Na IX, Mg X, and Si XII, which connect the physical conditions of these ultraviolet outflows to the X-ray warm absorber outflows seen in nearby Seyfert galaxies. Three of the outflows have two or three independent diagnostics for the electron number density, yielding consistent values for each outflow, which increase the robustness of the $R$ determinations. Troughs from never-before-seen ionic transitions of Ar VI, O IV*, Ne VI*, and Ne V* are identified. With a combined $\dot{E_k}$ that is $7.0^{+6.5}_{-2.3}$ % of the quasar's Eddington luminosity, these outflows are prime candidates to be major agents for various active galactic nuclei feedback effects.
- [38] arXiv:2003.08691 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500 -- 1050 Å Rest Frame: IV. The Largest Broad Absorption Line AccelerationComments: 10 pages, 6 figures, published in ApJSJournal-ref: 2020ApJS 247 40Subjects: Astrophysics of Galaxies (astro-ph.GA)
We present an analysis of the broad absorption line (BAL) velocity shift that appeared in one of the outflow systems in quasar SDSS J1042+1646. Observations were taken by the Hubble Space Telescope/Cosmic Origin Spectrograph in 2011 and 2017 in the 500 -- 1050 $\r{A}$ rest frame. The outflow's velocity centroid shifted by $\sim$ --1550 km s$^{-1}$ from --19,500 km s$^{-1}$ to --21,050 km s$^{-1}$ over a rest-frame time of 3.2 yr. The velocity shift signatures are most apparent in the absorption features from the Ne VIII $\lambda\lambda$ 770.41, 780.32 doublet and are supported by the absorption troughs from OV $\lambda$ 629.73 and the Mg X $\lambda\lambda$ 609.79, 624.94 doublet. This is the first time where a quasar outflow velocity shift is observed in troughs from more than one ion and in distinct troughs from a doublet transition (Ne VIII). We attribute the velocity shift to an acceleration of an existing outflow as we are able to exclude photoionization changes and motion of material into and out of the line of sight as alternate explanations. This leads to an average acceleration of 480 km s$^{-1}$ yr$^{-1}$ (1.52 cm s$^{-2}$) in the quasar rest frame. Both the acceleration and the absolute velocity shift are the largest reported for a quasar outflow to date. Based on the absorption troughs of the O V* multiplet, we derive a range for the distance of the outflow ($R$) from the central source, 0.05 pc $<$ $R$ $<$ 54.3 pc. This outflow shows similarities with the fast X-ray outflow detected in quasar PG 1211+143. We use the acceleration and velocity shift to constrain radiatively accelerated active galactic nucleus disk-wind models and use them to make predictions for future observations.
- [39] arXiv:2003.08692 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame: V. Richness of Physical Diagnostics and Ionization Potential-dependent Velocity Shift in PKS J0352-0711Comments: 12 pages, 9 figures, 5 tablesJournal-ref: ApJS 247 (2020) 41Subjects: Astrophysics of Galaxies (astro-ph.GA)
We analyze absorption troughs from two outflows within PKS J0352-0711 (S1 at $-$1950 km s$^{-1}$ and S2 at $-$3150 km s$^{-1}$) from spectra taken with Hubble Space Telescope/Cosmic Origin Spectrograph, which cover the diagnostic-rich 585-900 Angstrom rest frame wavelength range. In S2, for the first time we clearly detect absorption troughs from Ca IV, Ca V, Ca V*, Ca VII*, and Ca VIII*. The column density measurement of Ca V suggests S2 has a super-solar metallicity. Both outflows require at least two ionization phases where the column density of the very high-ionization phase is roughly 15 times larger than the corresponding high-ionization phase. These high column densities and very high-ionization potential ions are similar to X-ray warm absorbers. The two phases of S2 show a unique velocity centroid shift between associated troughs. Through Monte Carlo measurements of the O V* absorption troughs, we determine the electron number density of S2 (fully corroborated by independent measurements from the Ca V* and Ca VIII* troughs), yielding a distance of 9 pc and a kinetic luminosity of 2$\times$10$^{43}$ erg s$^{-1}$. S1 is located farther away at 500 pc from the central source with a kinetic luminosity of 10$^{43}$ erg s$^{-1}$.
- [40] arXiv:2003.08693 [pdf, other]
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Title: HST/COS Observations of Quasar Outflows in the 500 -- 1050 Å Rest Frame: VI Wide, Energetic Outflows in SDSS J0755+2306Comments: 10 pages, 6 figures, published in ApJSJournal-ref: 2020ApJS 247 42Subjects: Astrophysics of Galaxies (astro-ph.GA)
We present the analysis of two outflows (S1 at --5500 km s$^{-1}$ and S2 at --9700 km s$^{-1}$) seen in recent HST/COS observations of quasar SDSS J0755+2306 (z = 0.854). The outflows are detected as absorption troughs from both high-ionization species, including N III, O III, and S IV, and very high-ionization species, including Ar VIII, Ne VIII, and Na IX. The derived photoionization solutions show that each outflow requires a two ionization-phase solution. For S1, troughs from S IV* and S IV allow us to derive an electron number density, $n_{e}$ = 1.8$\times$10$^4$ cm$^{-3}$, and its distance from the central source of $R$ = 270 pc. For S2, troughs from O III* and O III yield $n_{e}$ = 1.2$\times$10$^3$ cm$^{-3}$ and $R$ = 1600 pc. The kinetic luminosity of S2 is $>$ 12% of the Eddington luminosity for the quasar and therefore can provide strong AGN feedback effects. Comparison of absorption troughs from O III and O VI in both outflow systems supports the idea that for a given element, higher ionization ions have larger covering fractions than lower ionization ones.
- [41] arXiv:2003.08701 [pdf, other]
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Title: EeV Astrophysical neutrinos from FSRQs?Comments: 9 pages, 7 figures, submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Flat Spectrum Radio Quasars (FSRQ) are the most powerful blazars in the gamma-ray band. Although they are supposed to be good candidates in producing high energy neutrinos, no secure detection of FSRQs has been obtained up to now, except for a possible case of PKS B1424-418. In this work, we compute the expected flux of high energy neutrinos from FSRQs using standard assumptions for the properties of the radiation fields filling the regions surrounding the central supermassive black hole. We obtain as a result that high energy neutrinos are naturally expected from FSRQs in the sub-EeV-EeV energy range and not at PeV energies. This justifies the non-observation of neutrinos from FSRQs with the present technology, since only neutrinos below 10 PeV have been observed. We found that for a non-negligible range of the parameters the cumulative flux from FSRQs is comparable to or even exceeds the expected cosmogenic neutrino flux. This result is intriguing and highlights the importance to disentangle these point-source emissions from the diffuse cosmogenic background.
- [42] arXiv:2003.08724 [pdf, other]
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Title: The 2016 Vela glitch: A key to neutron star internal structure and dynamicsComments: 9 pages with 2 figures, submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
High resolution, pulse to pulse observation of the 2016 Vela glitch and its relaxation provided an opportunity to probe the neutron star internal structure and dynamics with unprecedented detail. We use the observations of this glitch to infer superfluid characteristics in the framework of the vortex creep model. The glitch rise time constraint of 12.6 seconds put stringent limits on the angular momentum exchange between the crustal superfluid and the observed crust. Together with the observed excess acceleration in the rotation rate as compared to the post-glitch equilibrium value this discriminates crustal superfluid-crust lattice and core superfluid-crustal normal matter coupling time-scales. An evident decrease in the crustal rotation rate immediately before the glitch is consistent with the formation of a new vortex trap zone that initiates the large scale vortex unpinning avalanche.
- [43] arXiv:2003.08776 [pdf, other]
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Title: Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. III. Blazar S5 0716+71 at microarcsecond resolutionAuthors: Evgeniya V. Kravchenko (IRA INAF, ASC Lebedev), Jose L. Gómez (IAA CSIC), Yuri Y. Kovalev (ASC Lebedev, MIPT, MPIfR), Andrei P. Lobanov, Tuomas Savolainen, Gabriele Bruni, Antonio Fuentes, James M. Anderson, Svetlana G. Jorstad, Alan P. Marscher, Merja Tornikoski, Anne Lähteenmäki, Mikhail M. LisakovComments: 16 pages, 6 figures, 3 tables; accepted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present RadioAstron Space VLBI imaging observations of the BL Lac object S5 0716+71 made on January 3-4 2015 at a frequency of 22 GHz (wavelength $\lambda=1.3$ cm). The observations were made in the framework of the AGN Polarization Key Science Program. The source was detected on projected space-ground baselines up to 70 833 km (5.6 Earth diameters) for both, parallel hand and cross-hand interferometric visibilities. We have used these detections to obtain a full-polarimetric image of the blazar at an unprecedented angular resolution of 24 $\mu$as, the highest for this source to date. This enabled us to estimate the size of the radio core to be $<12\times5~\mu$as and to reveal a complex structure and a significant curvature of the blazar jet in the inner 100 $\mu$as, which is an indication that the jet viewing angle lies inside the opening angle of the jet conical outflow. Fairly highly (15%) linearly polarized emission is detected in a jet region of 19 $\mu$as in size, located 58 $\mu$as downstream from the core. The highest brightness temperature in the source frame is estimated to be $>2.2\times10^{13}$ K for the blazar core. This implies that the inverse Compton limit must be violated in the rest frame of the source, even for the largest Doppler factor $\delta\thicksim25$ reported for 0716+714.
- [44] arXiv:2003.08812 [pdf, other]
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Title: Global trends in winds of M dwarf starsComments: 12 pages, 11 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
M dwarf stars are currently the main targets in searches for potentially habitable planets. However, their winds have been suggested to be harmful to planetary atmospheres. Here, in order to better understand the winds of M dwarfs and also infer their physical properties, we perform a one-dimensional magnetohydrodynamic parametric study of winds of M dwarfs that are heated by dissipation of Alfv\'en waves. These waves are triggered by sub-surface convective motions and propagate along magnetic field lines. Here, we vary the magnetic field strength and density at the wind base (chromosphere), while keeping the same relative wave amplitude ($0.1 B_0$) and dissipation lenghtscale. We find that our winds very quickly reach isothermal temperatures with mass-loss rates proportional to base density square. We compare our results with Parker wind models and find that, in the high-beta regime, both models agree. However, in the low-beta regime, the Parker wind underestimates the terminal velocity by around one order of magnitude and mass-loss rate by several orders of magnitude. We also find that M dwarfs could have chromospheres extending to 18% to 180% of the stellar radius. We apply our model to the planet-hosting star GJ 436 and find, from X-ray observational constraints, $\dot{M}<7.6\times 10^{-15}\,M_{\odot}~\text{yr}^{-1}$. This is in agreement with values derived from the Lyman-alpha transit of GJ 436b, indicating that spectroscopic planetary transits could be used as a way to study stellar wind properties.
- [45] arXiv:2003.08827 [pdf, other]
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Title: Outflow from Outer-arm Starburst in a Grazing Collision between GalaxiesAuthors: Michele Kaufman, Bruce G. Elmegreen, Morten Andersen, Debra Meloy Elmegreen, Curtis Struck, Frederic Bournaud, Elias Brinks, James C. McGarryComments: accepted by AJSubjects: Astrophysics of Galaxies (astro-ph.GA)
New ALMA CO, HCO+, and 100 GHz continuum observations and Gemini NIFS K-band spectra are combined with previous radio to X-ray data to study Feature i, a highly luminous starburst clump on an outer arm of the interacting galaxy NGC 2207. This clump has an optically-opaque dust cone extending out of its 170 pc core. The measured CO accounts for the dark cone extinction if almost all the gas and dust there is in front of the star clusters. An associated approaching CO outflow has v_z ~ 16 km/s, an estimated molecular mass 8 x 10^6 Msun, and rises to heights ~ 0.9 kpc. A receding CO outflow on the far side with v_z ~ 28 km/s is less extensive. The observed star formation in the core over 10 Myr can supply the dark cone kinetic energy via supernovae and stellar winds. Other signs of intense activity are variable radio continuum suggesting an embedded supernova or other outburst, X-ray emission, and Br-gamma and He I lines with 82 km/s line widths. According to previous models, the retrograde encounter suffered by NGC 2207 caused loss of angular momentum. This compressed its outer disk. We suggest that the resulting inward crashing gas stream hit a massive HI cloud as it was being compressed by a spiral density wave and triggered the observed starburst.
- [46] arXiv:2003.08845 [pdf]
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Title: Galaxies with Declining Rotation CurvesComments: 15 pages, 11 figuresJournal-ref: Astronomy Reports, 2020, Vol. 64, No. 4, pp. 295-309Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
A sample of 22 spiral galaxies compiled from published data is studied. The galaxy rotation curves pass through a maximum distance of more than $\sim 1$ kpc from the center with a subsequent decrease in the rotation velocity. The galaxy position in the Tully-Fisher (TF) and baryonic Tully-Fisher (BTF) diagrams show that the values of maximum rotation velocities are located on the same sequence with other galaxies, while the velocities at the disk periphery for some galaxies are significantly lower than the expected values for a given mass or luminosity. Thus, the decrease in the rotation curve can be associated with a reduced contribution of the dark halo to the rotation velocity. For seven galaxies with the longest rotation curves, the disk mass was estimated to be with the dark halo (Newtonian model) and without the halo (modified Newtonian dynamics (MOND) model). In four of the galaxies, the MOND model encounters difficulties in interpreting the rotation curve: in order to be consistent with the observations, the MOND parameter $a_0$ should differ significantly from the expected value $a_0 \sim 10^{-8}$ cm/s$^2$, while the disk mass exceeds the value based on IR photometry and maximum disk model. The conflict with MOND is the most significant for NGC 157.
- [47] arXiv:2003.08848 [pdf, ps, other]
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Title: Subaru medium-resolution spectra of a QSO at z=6.62: Three reionization testsAuthors: Ting-Yi Lu, Tomotsugu Goto, Ji-Jia Tang, Tetsuya Hashimoto, Yi-Hang Valerie Wong, Chia-Ying Chang, Yi-Han Wu, Seong Jin Kim, Chien-Chang Ho, Ting-Wen Wang, Alvina Y. L. On, Daryl Joe D. SantosComments: 15 pages, 10 figures, 5 tables, Accepted for Publication in ApJSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Investigating the Gunn-Peterson trough of high redshift quasars (QSOs) is a powerful way to reveal the cosmic reionization. As one of such attempts, we perform a series of analyses to examine the absorption lines observed with one of the highest redshift QSOs, PSO J006.1240+39.2219, which we previously discovered at z = 6.62. Using the Subaru telescope, we obtained medium-resolution spectrum with a total exposure time of 7.5 hours. We calculate the Ly$\alpha$ transmission in different redshift bins to determine the near zone radius and the optical depth at 5.6$<$z$<$6.5. We find a sudden change in the Ly$\alpha$ transmission at 5.75$<$z$<$5.86, which is consistent with the result from the literature. The near zone radius of the QSO is 5.79$\pm$0.09 $p$Mpc, within the scatter of the near zone radii of other QSOs measured in previous studies. We also analyze the dark gap distribution to probe the neutral hydrogen fractions beyond the saturation limit of the Gunn-Peterson trough. We extend the measurement of the dark gaps to 5.7$<$z$<$6.3. We find that the gap widths increase with increasing redshifts, suggesting more neutral Universe at higher redshifts. However, these measurements strongly depend on the continuum modeling. As a continuum model-free attempt, we also perform the dark-pixel counting analysis, to find the upper limit of $\langle x_{\rm H I} \rangle \sim$0.6 (0.8) at $z<$5.8 ($z>$5.8). All three analyses based on this QSO show increasingly neutral hydrogen towards higher redshifts, adding precious measurements up to z$\sim$6.5.
- [48] arXiv:2003.08851 [pdf, other]
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Title: An Extreme Precision Radial Velocity Pipeline: First Radial Velocities from EXPRESAuthors: Ryan R. Petersburg, J. M. Joel Ong, Lily L. Zhao, Ryan T. Blackman, John M. Brewer, Lars A. Buchhave, Samuel H. C. Cabot, Allen B. Davis, Colby A. Jurgenson, Christopher Leet, Tyler M. McCracken, David Sawyer, Mikhail Sharov, René Tronsgaard, Andrew E. Szymkowiak, Debra A. FischerSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The EXtreme PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, $R=137,500$, optical spectrograph. It was recently commissioned at the 4.3-m Lowell Discovery Telescope (LDT) near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30$\mathrm{~cm~s^{-1}}$. In addition to instrumental innovations, the EXPRES pipeline, presented here, is the first for an on-sky, optical, fiber-fed spectrograph to employ many novel techniques---including an "extended flat" fiber used for wavelength-dependent quantum efficiency characterization of the CCD, a flat-relative optimal extraction algorithm, chromatic barycentric corrections, chromatic calibration offsets, and an ultra-precise laser frequency comb for wavelength calibration. We describe the reduction, calibration, and radial-velocity analysis pipeline used for EXPRES and present an example of our current sub-meter-per-second RV measurement precision, which reaches a formal, single-measurement error of 0.3$\mathrm{~m~s^{-1}}$ for an observation with a per-pixel signal-to-noise ratio of 250. These velocities yield an orbital solution on the known exoplanet host 51 Peg that matches literature values with a residual RMS of 0.895$\mathrm{~m~s^{-1}}$.
- [49] arXiv:2003.08852 [pdf, other]
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Title: Performance Verification of the EXtreme PREcision SpectrographAuthors: Ryan T. Blackman, Debra A. Fischer, Colby A. Jurgenson, David Sawyer, Tyler M. McCracken, Andrew E. Szymkowiak, Ryan R. Petersburg, J. M. Joel Ong, John M. Brewer, Lily L. Zhao, Christopher Leet, Lars A. Buchhave, René Tronsgaard, Joe Llama, Travis Sawyer, Allen B. Davis, Samuel H. C. Cabot, Michael Shao, Russell Trahan, Bijan Nemati, Matteo Genoni, Giorgio Pariani, Marco Riva, Rafael A. Probst, Ronald Holzwarth, Tilo Steinmetz, Paul Fournier, Rafal PawluczykComments: 39 pages, 30 figures, accepted to AJSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The EXtreme PREcision Spectrograph (EXPRES) is a new Doppler spectrograph designed to reach a radial velocity measurement precision sufficient to detect Earth-like exoplanets orbiting nearby, bright stars. We report on extensive laboratory testing and on-sky observations to quantitatively assess the instrumental radial velocity measurement precision of EXPRES, with a focused discussion of individual terms in the instrument error budget. We find that EXPRES can reach a single-measurement instrument calibration precision better than 10 cm/s, not including photon noise from stellar observations. We also report on the performance of the various environmental, mechanical, and optical subsystems of EXPRES, assessing any contributions to radial velocity error. For atmospheric and telescope related effects, this includes the fast tip-tilt guiding system, atmospheric dispersion compensation, and the chromatic exposure meter. For instrument calibration, this includes the laser frequency comb (LFC), flat-field light source, CCD detector, and effects in the optical fibers. Modal noise is mitigated to a negligible level via a chaotic fiber agitator, which is especially important for wavelength calibration with the LFC. Regarding detector effects, we empirically assess the impact on radial velocity precision due to pixel-position non-uniformities (PPNU) and charge transfer inefficiency (CTI). EXPRES has begun its science survey to discover exoplanets orbiting G-dwarf and K-dwarf stars, in addition to transit spectroscopy and measurements of the Rossiter-McLaughlin effect.
- [50] arXiv:2003.08901 [pdf, other]
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Title: Testing the isotropy of the Dark Energy Survey's extreme trans-Neptunian objectsAuthors: Pedro H. Bernardinelli, Gary M. Bernstein, Masao Sako, Stephanie Hamilton, David W. Gerdes, Fred C. Adams, William R. Saunders, M. Aguena, S. Allam, S. Avila, D. Brooks, H. T. Diehl, P. Doel, S. Everett, J. García-Bellido, E. Gaztanaga, R. A. Gruendl, K. Honscheid, R. L. C. Ogando, A. Palmese, D. L. Tucker, A. R. Walker (the DES collaboration)Comments: Submitted to AAS journalsSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We test whether the population of "extreme" trans-Neptunian objects (eTNOs) detected in the Y4 Dark Energy Survey (DES) data exhibit azimuthal asymmetries which might be evidence of gravitational perturbations from an unseen super-Earth in a distant orbit. By rotating the orbits of the detected eTNOs, we construct a synthetic population which, when subject to the DES selection function, reproduces the detected distribution of eTNOs in the orbital elements $a,e,$ and $i$ as well as absolute magnitude $H$, but has uniform distributions in mean anomaly $M$, longitude of ascending node $\Omega,$ and argument of perihelion $\omega.$ We then compare the detected distributions in each of $\Omega, \omega,$ and $\varpi\equiv\Omega+\omega$ to those expected from the isotropic population, using Kuiper's variant of the Kolmogorov-Smirnov test. The three angles are tested for each of 4 definitions of the eTNO population, choosing among $a>(150,250)$~AU and perihelion $q>(30,37)$~AU. These choices yield 3--7 eTNOs in the DES Y4 sample. Among the twelve total tests, two have the likelihood of drawing the observed angles from the isotropic population at $p<0.05.$ The 3 detections at $a>250, q>37$~AU, and the 4 detections at $a>250, q>30$~AU, have $\Omega$ distribution with $p=0.03$ of coming from the isotropic construction, but this is not strong evidence of anisotropy given the 12 different tests. The DES data taken on their own are thus consistent with azimuthal isotropy and do not require a "Planet 9" hypothesis. The limited sky coverage and object count mean, however, that the DES data by no means falsify this hypothesis.
- [51] arXiv:2003.08905 [pdf, other]
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Title: On the asteroseismic sensitivity to internal rotation along the red-giant branchComments: accepted for publication in Astronomy and AstrophysicsSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
The transport of angular momentum in stellar interiors is currently not well understood. Asteroseismology can provide us with estimates of internal rotation of stars and thus advance our understanding of angular momentum transport. We can measure core-rotation rates in red-giant stars and we can place upper bounds on surface-rotation rates using measurements of dipole ($l=1$) modes. Here, we aim to determine the theoretical sensitivity of modes of different degree towards the surface rotation. Additionally, we aim to identify modes that can potentially add sensitivity at intermediate radii. We use asteroseismic rotational inversions to probe the internal stellar rotation profiles in red-giant models from the base of the red-giant branch up to the luminosity bump. We calculate the internal rotation rates using multiplicative optimally localised averages (MOLA) inversions for different mode sets and different synthetic rotation profiles. We confirm that dipole mixed modes are sufficient to set constraints on the average core-rotation rates in red giants. However, surface-rotation rates estimated with only dipole mixed modes are contaminated by the core rotation. We show that the sensitivity to the surface rotation decreases from the base of the red-giant branch until it reaches a minimum at $0.6-0.8L_\text{bump}$ due to a glitch in the buoyancy frequency. Thereafter a narrow range of increased surface sensitivity just below the bump luminosity exists. Quadrupole and octopole modes have more sensitivity in the outer parts of the star. If observed, quadrupole and octopole modes enable us to distinguish between differential and solid body rotation in the convection zone. To obtain accurate estimates of rotation rates at intermediate radii (i.e. a fractional radius of $\sim0.4$), acoustic oscillation modes with a spherical degree of $l\approx10$ are needed.
- [52] arXiv:2003.08922 [pdf, other]
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Title: A Sub-Solar Metallicity Progenitor for Cassiopeia A, the remnant of a Type IIb SupernovaAuthors: Toshiki Sato, Takashi Yoshida, Shigehiro Nagataki, Masaomi Ono, Keiichi Maeda, Ryosuke Hirai, John P. Hughes, Brian J. Williams, Yoshitomo MaedaComments: 13 pages, 5 figure. Accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We report, for the first time, the detection of the Mn-K$\alpha$ line in the Type IIb supernova (SN IIb) remnant, Cassiopeia A. Manganese ($^{55}$Mn after decay of $^{55}$Co), a neutron-rich element, together with chromium ($^{52}$Cr after decay of $^{52}$Fe), is mainly synthesized at the explosive incomplete Si burning regime. Therefore, the Mn/Cr mass ratio with its neutron excess reflects the neutronization at the relevant burning layer during the explosion. Chandra's archival X-ray data of Cassiopeia A indicate a low Mn/Cr mass ratio with values in the range 0.10--0.66, which, when compared to one-dimensional SN explosion models, requires that the electron fraction be 0.4990 $\lesssim Y_{\rm e} \lesssim$ 0.5 at the incomplete Si burning layer. An explosion model assuming a solar-metallicity progenitor with a typical explosion energy ($1 \times 10^{51}$ erg) fails to reproduce such a high electron fraction. In such models, the explosive Si-burning regime extends only to the Si/O layer established during the progenitor's hydrostatic evolution; the $Y_e$ in the Si/O layer is lower than the value required by our observational constraints. We can satisfy the observed Mn/Cr mass ratio if the explosive Si-burning regime were to extend into the O/Ne hydrostatic layer, which has a higher $Y_{\rm e}$. This would require an energetic ($> 2 \times 10^{51}$ erg) and/or asymmetric explosion of a sub-solar metallicity progenitor ($Z \lesssim 0.5Z_{\odot}$) for Cassiopeia A. The low initial metallicity can be used to rule out a single-star progenitor, leaving the possibility of a binary progenitor with a compact companion (white dwarf, neutron star or black hole). We discuss the detectability of X-rays from Bondi accretion onto such a compact companion around the explosion site. We also discuss other possible mass-loss scenarios for the progenitor system of Cassiopeia A.
- [53] arXiv:2003.08924 [pdf, ps, other]
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Title: Interpreting solar wind turbulent spectra beyond THComments: Accepted for publication in ApJLSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
In this paper we apply a methodology, recently proposed by Bourouaine and Perez (2019) (BP19), to interpret solar-wind turbulent power spectra beyond Taylor approximation (TA). The turbulent power spectra were measured using \emph{Helios} spacecraft data near 0.6 au. We use the model proposed in BP19 to reproduce the field-perpendicular power spectrum $E(k_\perp)$ of anti-sunward Alfv\'enic fluctuations in the plasma frame (where $k_\perp$ is the field-perpendicular wavenumber) from the corresponding measured frequency power spectrum $P_{\rm sc}(\omega,\theta_b)$ along the sampling angle $\theta_b$, which is the angle between the local magnetic field and the sampling direction. Here $\omega=2\pi f$ and $f$ is the frequency of the time signal. Interestingly enough, we found that for all corresponding measured frequency power spectrum $P_{\rm sc}(\omega,\theta_b)$ the reproduced field-perpendicular power spectrum $E(k_\perp)$ is the same and independent of the considered sampling angle $\theta_b$. This finding is consistent with the fact that the analyzed turbulence is strong and highly anisotropic with $k_\| \ll k_\perp$ (where $k_\|$ is the field-parallel wavenumber). Furthermore, for this specific time signal we found that the commonly used TA is still approximately valid with the important difference that a broadening in $k_\perp$ for each angular frequency $\omega$ is present. This broadening can be described in the context of the methodology proposed in BP19.
- [54] arXiv:2003.08928 [pdf, other]
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Title: A Systematic Analysis of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GRS 1915+105Authors: Liang Zhang, Mariano Méndez, Diego Altamirano, Jinlu Qu, Li Chen, Konstantinos Karpouzas, Tomaso M. Belloni, Qingcui Bu, Yue Huang, Xiang Ma, Lian Tao, Yanan WangComments: 12 pages, 17 figures, accepted for publication in MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present a systematic analysis of the phase lags associated with the type-C QPOs in GRS 1915+105 using RXTE data. Our sample comprises of 620 RXTE observations with type-C QPOs ranging from ~0.4 Hz to ~6.3 Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ~2 Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ~1 Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag-energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag-energy spectra drives the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.
Cross-lists for Fri, 20 Mar 20
- [55] arXiv:2003.08394 (cross-list from physics.comp-ph) [pdf, other]
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Title: Convergence of Artificial Intelligence and High Performance Computing on NSF-supported CyberinfrastructureAuthors: E. A. Huerta, Asad Khan, Edward Davis, Colleen Bushell, William D. Gropp, Daniel S. Katz, Volodymyr Kindratenko, Seid Koric, William T. C. Kramer, Brendan McGinty, Kenton McHenry, Aaron SaxtonComments: White paper accepted to the NSF Workshop on Smart Cyberinfrastructure, February 25-27, 2020 this http URLSubjects: Computational Physics (physics.comp-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); General Relativity and Quantum Cosmology (gr-qc)
Significant investments to upgrade or construct large-scale scientific facilities demand commensurate investments in R&D to design algorithms and computing approaches to enable scientific and engineering breakthroughs in the big data era. The remarkable success of Artificial Intelligence (AI) algorithms to turn big-data challenges in industry and technology into transformational digital solutions that drive a multi-billion dollar industry, which play an ever increasing role shaping human social patterns, has promoted AI as the most sought after signal processing tool in big-data research. As AI continues to evolve into a computing tool endowed with statistical and mathematical rigor, and which encodes domain expertise to inform and inspire AI architectures and optimization algorithms, it has become apparent that single-GPU solutions for training, validation, and testing are no longer sufficient. This realization has been driving the confluence of AI and high performance computing (HPC) to reduce time-to-insight and to produce robust, reliable, trustworthy, and computationally efficient AI solutions. In this white paper, we present a summary of recent developments in this field, and discuss avenues to accelerate and streamline the use of HPC platforms to design accelerated AI algorithms.
- [56] arXiv:2003.08428 (cross-list from gr-qc) [pdf, other]
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Title: Hamiltonian theory of classical and quantum gauge invariant perturbations in Bianchi I spacetimesComments: 41 pages, 3 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We derive a Hamiltonian formulation of the theory of gauge invariant, linear perturbations in anisotropic Bianchi I spacetimes, and describe how to quantize this system. The matter content is assumed to be a minimally coupled scalar field with potential $V(\phi)$. We show that a Bianchi I spacetime generically induces both anisotropies and quantum entanglement on cosmological perturbations, and provide the tools to compute the details of these features. We then apply this formalism to a scenario in which the inflationary era is preceded by an anisotropic Bianchi I phase, and discuss the potential imprints in observable quantities. The formalism developed here paves the road to a simultaneous canonical quantization of both the homogeneous degrees of freedom and the perturbations, a task that we develop in a companion paper.
- [57] arXiv:2003.08448 (cross-list from gr-qc) [pdf, other]
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Title: Model independent tests of the Kerr bound with extreme mass ratio inspiralsComments: 5 pages, 3 figures, data available at this https URLSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
An outstanding prediction of general relativity is the fact that the angular momentum $S$ of an isolated black hole with mass $\mu$ is limited by the Kerr bound, $S\leq G\mu^2/c$. Testing this cornerstone is challenging due to the difficulty in modelling spinning compact objects that violate this bound. We show that precise, model-independent tests can be achieved by measuring gravitational waves from an extreme mass ratio inspiral around a supermassive object, one of the main targets of the future LISA mission. In the extreme mass ratio limit the dynamics of the small compact object depends on its multipole moments, but not on the details of its structure. Thus, its spin is a free parameter and can exceed the Kerr bound. By computing the orbital dephasing and the gravitational-wave signal emitted by a generically spinning point particle in circular, equatorial motion around a Kerr black hole, we estimate that LISA will be able to measure the spin of the small compact object at the level of $10\%$, also allowing for theory-agnostic, unprecedented constraints on string-theory inspired objects such as "superspinars", almost in their entire parameter space.
- [58] arXiv:2003.08508 (cross-list from math.NA) [pdf, other]
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Title: An Application of Gaussian Process Modeling for High-order Accurate Adaptive Mesh Refinement ProlongationSubjects: Numerical Analysis (math.NA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Fluid Dynamics (physics.flu-dyn)
We present a new polynomial-free prolongation scheme for Adaptive Mesh Refinement (AMR) simulations of compressible and incompressible computational fluid dynamics. The new method is constructed using a multi-dimensional kernel-based Gaussian Process (GP) prolongation model. The formulation for this scheme was inspired by the GP methods introduced by A. Reyes et al. (A New Class of High-Order Methods for Fluid Dynamics Simulation using Gaussian Process Modeling, Journal of Scientific Computing, 76 (2017), 443-480; A variable high-order shock-capturing finite difference method with GP-WENO, Journal of Computational Physics, 381 (2019), 189-217). In this paper, we extend the previous GP interpolations and reconstructions to a new GP-based AMR prolongation method that delivers a high-order accurate prolongation of data from coarse to fine grids on AMR grid hierarchies. In compressible flow simulations special care is necessary to handle shocks and discontinuities in a stable manner. To meet this, we utilize the shock handling strategy using the GP-based smoothness indicators developed in the previous GP work by A. Reyes et al. We demonstrate the efficacy of the GP-AMR method in a series of testsuite problems using the AMReX library, in which the GP-AMR method has been implemented.
- [59] arXiv:2003.08511 (cross-list from hep-ph) [pdf, other]
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Title: Addendum to: Global constraints on absolute neutrino masses and their orderingAuthors: Francesco Capozzi, Eleonora Di Valentino, Eligio Lisi, Antonio Marrone, Alessandro Melchiorri, Antonio PalazzoComments: 9 pages, including 3 tables and 5 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
We revisit our previous work [Phys. Rev. D 95, 096014 (2017)] where neutrino oscillation and nonoscillation data were analyzed in the standard framework with three neutrino families, in order to constrain their absolute masses and to probe their ordering (either normal, NO, or inverted, IO). We include updated oscillation results to discuss best fits and allowed ranges for the two squared mass differences $\delta m^2$ and $\Delta m^2$, the three mixing angles $\theta_{12}$, $\theta_{23}$ and $\theta_{13}$, as well as constraints on the CP-violating phase $\delta$, plus significant indications in favor of NO vs IO at the level of $\Delta\chi^2=10.0$. We then consider nonoscillation data from beta decay, from neutrinoless double beta decay (if neutrinos are Majorana), and from various cosmological input combinations dubbed as default, aggressive, and conservative. In the default option, we obtain from nonoscillation data an extra contribution $\Delta\chi^2 = 2.2$ in favor of NO, and an upper bound on the sum of neutrino masses $\Sigma < 0.15$ eV at $2\sigma$; both results - dominated by cosmology - can be strengthened or weakened by using more aggressive or conservative options, respectively. Taking into account such variations, we find that the combination of all (oscillation and nonoscillation) neutrino data favors NO at the level of $3.2-3.7\sigma$, and that $\Sigma$ is constrained at the $2\sigma$ level within $\Sigma < 0.12-0.69$ eV. The upper edge of this allowed range corresponds to an effective $\beta$-decay neutrino mass $m_\beta = \Sigma/3 = 0.23$ eV, at the sensitivity frontier of the KATRIN experiment.
- [60] arXiv:2003.08516 (cross-list from hep-th) [pdf, ps, other]
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Title: Palatini quadratic gravity: spontaneous breaking of gauged scale symmetry and inflationAuthors: D. M. GhilenceaComments: 18 pages, 2 figures, LaTeXSubjects: 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)
We study $R^2$ gravity with a dynamical connection ($\tilde\Gamma^\alpha_{\mu\nu}$) in the Palatini formalism where the metric and connection are independent. The action has a gauged scale symmetry (Weyl gauging) of gauge field $v_\mu\propto \tilde\Gamma_\mu-\Gamma_\mu$, with $\tilde\Gamma_\mu$ ($\Gamma_\mu$) the trace of the Palatini (Levi-Civita) connection, respectively. In this case the associated geometry is non-metric. We show that the gauge field becomes massive by a gravitational Stueckelberg mechanism by absorbing the derivative of the dilaton $\partial_\mu\ln\phi$ (where the scalar $\phi$ "linearises" the $R^2$ term). Palatini quadratic gravity with dynamical $v_\mu$ is then a gauged scale invariant theory broken spontaneously. In the broken phase one finds the Einstein-Proca action of $v_\mu$ of mass near the Planck scale ($M$) with a positive cosmological constant. Below this scale $v_\mu$ decouples, the connection becomes Levi-Civita and metricity and Einstein gravity are recovered. The results remain valid in the presence of non-minimally coupled matter. This is similar to recent results by the author for Weyl quadratic gravity, up to different non-metricity effects. When coupled to a scalar field, Palatini quadratic gravity gives successful inflation and a specific prediction for the tensor-to-scalar ratio $0.007\leq r \leq 0.01$ for current spectral index $n_s$ (at $95\%$CL) and $N=60$ efolds. This value of $r$ is mildly larger than in inflation in Weyl gravity, due to different non-metricity. This establishes a connection between non-metricity and inflation predictions and enables us to test these theories by future CMB experiments.
- [61] arXiv:2003.08822 (cross-list from physics.space-ph) [pdf]
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Title: Automatic Region Identification over the MMS Orbit by Partitioning n-T spaceSubjects: Space Physics (physics.space-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Space plasma data analysis and mission operations are aided by the categorization of plasma data between different regions of the magnetosphere and identification of the boundary regions between them. Without computerized automation this means sorting large amounts of data to hand-pick regions. Using hand-labeled data created to support calibration of the Fast Plasma Instrument, this task was automated for the MMS mission with 99.9% accuracy. The method partitions the number density and ion temperature plane into sub-planes for each region, fitting boundaries between the sub-planes using a machine learning technique known as the support vector machine. This method presented in this paper is novel because it offers both statistical automation power and interpretability that yields scientific insight into how the task is performed.
- [62] arXiv:2003.08832 (cross-list from gr-qc) [pdf, other]
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Title: Galaxy rotation curves from external influence on Schwarzschild geometryAuthors: A. BhattacharyayComments: 4 pages and one figureSubjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA)
In this paper a perturbation of the large distance (weak field) part of a Schwarzschild metric is considered. The perturbation is motivated by the applicability of superposition in the weak fields and the idea of perturbing Minkowski space is abandoned. This perturbation is characterized by a parameter which turns out to be inverse of the length scale which is of the order of $10^{7}$ kpc (kiloparsec). This is the order of the radius of the observable universe. Existence of a good range of galaxy rotation curves can be a accounted for by this phenomenology.
- [63] arXiv:2003.08873 (cross-list from physics.chem-ph) [pdf, other]
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Title: Adsorption of H$_2$ on Amorphous Solid Water Studied with Molecular Dynamics SimulationsComments: Quantum-chemistry based study of the adsorption dynamics of H2 on amorphous solid waterSubjects: Chemical Physics (physics.chem-ph); Astrophysics of Galaxies (astro-ph.GA)
We investigated the behavior of H$_2$, main constituent of the gas phase in dense clouds, after collision with amorphous solid water (ASW) surfaces, one of the most abundant chemical species of interstellar ices. We developed a general framework to study the adsorption dynamics of light species on interstellar ices. We provide binding energies and their distribution, sticking probabilities for incident energies between 1 meV and 60 meV, and thermal sticking coefficients between 10 and 300 K for surface temperatures from 10 to 110 K. We found that the sticking probability depends strongly on the adsorbate kinetic energy and the surface temperature, but hardly on the angle of incidence. We observed finite sticking probabilities above the thermal desorption temperature. Adsorption and thermal desorption should be considered as separate events with separate time scales. Laboratory results for these species have shown a gap in the trends attributed to the differently employed experimental techniques. Our results complement observations and extend them, increasing the range of gas temperatures under consideration. We plan to employ our method to study a variety of adsorbates, including radical and charged species.
- [64] arXiv:2003.08908 (cross-list from gr-qc) [pdf, ps, other]
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Title: Primordial flat frame -- a new view on inflationAuthors: C. WetterichComments: 26 pages, a small part overlaps with v1 of 1912.00792 which will be split into two papersSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
Models of inflationary cosmology admit a choice of the metric for which geometry becomes flat Minkowski space in the infinite past. In this primordial flat frame all mass scales vanish in the infinite past and quantum scale symmetry is realized. The cosmological evolution is dominantly described by the slow increase of a scalar field which sets the scale of all masses. We construct the primordial flat frame for standard models of inflation as Starobinski inflation or chaotic inflation. In particular, we discuss the evolution of inhomogeneous solutions in the neighborhood of the homogeneous isotropic background solution and their relation to the observable primordial fluctuation spectrum. Our observed inhomogeneous Universe can be extrapolated back to the infinite past in physical time. There is no physical big-bang singularity - the latter reflects only a singular choice of "field coordinates".
Replacements for Fri, 20 Mar 20
- [65] arXiv:1806.10564 (replaced) [pdf, other]
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Title: Synthetic Gaia surveys from the FIRE cosmological simulations of Milky Way-mass galaxiesAuthors: Robyn E. Sanderson (1), Andrew Wetzel (2), Sarah Loebman (2), Sanjib Sharma (3), Philip F. Hopkins (1), Shea Garrison-Kimmel (1), Claude-André Faucher-Giguère (4), Dušan Kereš (5), Eliot Quataert (6) ((1) California Institute of Technology, (2) University of California at Davis, (3) University of Sydney, (4) Northwestern University, (5) University of California at San Diego, (6), University of California Berkeley)Comments: Matches accepted version. Data accompanying this paper are available at this https URL and this https URL More info and updates at this http URLSubjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [66] arXiv:1903.06186 (replaced) [pdf, other]
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Title: A metal-poor damped Ly-alpha system at redshift 6.4Authors: Eduardo Banados, Michael Rauch, Roberto Decarli, Emanuele P. Farina, Chiara Mazzucchelli, Bram P. Venemans, Fabian Walter, Robert A. Simcoe, J. Xavier Prochaska, Thomas Cooper, Frederick B. Davies, Shi-Fan S. ChenComments: Updated to match published versionJournal-ref: The Astrophysical Journal, Volume 885, Issue 1, article id. 59, 15 pp. (2019)Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [67] arXiv:1908.07731 (replaced) [pdf]
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Title: GAUSS -- A Sample Return Mission to CeresAuthors: Xian Shi, Julie Castillo-Rogez, Henry Hsieh, Hejiu Hui, Wing-Huen Ip, Hanlun Lei, Jian-Yang Li, Federico Tosi, Liyong Zhou, Jessica Agarwal, Antonella Barucci, Pierre Beck, Adriano Campo Bagatin, Fabrizio Capaccioni, Andrew Coates, Gabriele Cremonese, Rene Duffard, Ralf Jaumann, Geraint Jones, Manuel Grande, Esa Kallio, Yangting Lin, Olivier Mousis, Andreas Nathues, Jürgen Oberst, Adam Showman, Holger Sierks, Stephan Ulamec, Mingyuan WangComments: Section 3.4 revised; List of team members updated; Typos correctedSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
- [68] arXiv:1909.01371 (replaced) [pdf, other]
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Title: Impact of the Rotation and Compactness of Progenitors on the Mass of Black HolesAuthors: Michela Mapelli, Mario Spera, Enrico Montanari, Marco Limongi, Alessandro Chieffi, Nicola Giacobbo, Alessandro Bressan, Yann BouffanaisComments: 15 pages, 5 figures, 1 table; updated to match the published version (Mapelli et al. 2020, ApJ, 888, 76)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [69] arXiv:1909.06385 (replaced) [pdf, other]
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Title: Revising natal kick prescriptions in population synthesis simulationsComments: 13 pages, 5 figures, 2 table, ApJ, in pressSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [70] arXiv:1909.07388 (replaced) [pdf, ps, other]
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Title: The assembly of dusty galaxies at $z \geq 4$: statistical propertiesComments: Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [71] arXiv:1909.09632 (replaced) [pdf, other]
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Title: Photometric Redshift Calibration with Self Organising MapsComments: 22 pages, 10 figures, 4 appendices, accepted for publication in A&ASubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [72] arXiv:1909.11107 (replaced) [pdf, other]
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Title: Constraining $M_ν$ with the Bispectrum I: Breaking Parameter DegeneraciesComments: 33 pages, 13 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [73] arXiv:1910.03588 (replaced) [pdf, other]
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Title: The Role of the Parker Instability in Structuring the Interstellar MediumComments: 26 pages, 22 figures, 1 table, accepted to ApJJournal-ref: ApJ 891 157 (2020)Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [74] arXiv:1910.09558 (replaced) [pdf, other]
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Title: Double white dwarf merger products among high-mass white dwarfsComments: 9 pages, 5 figures; published in ApJJournal-ref: The Astrophysical Journal, Volume 891, Issue 2, article id. 160, 7 pp. (2020)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
- [75] arXiv:1910.13662 (replaced) [pdf, other]
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Title: Constraining properties of neutron star merger outflows with radio observationsAuthors: Dougal Dobie, David L. Kaplan, Kenta Hotokezaka, Tara Murphy, Adam Deller, Gregg Hallinan, Samaya NissankeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [76] arXiv:1911.00057 (replaced) [pdf, ps, other]
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Title: Primordial Black Holes from a tiny bump/dip in the Inflaton potentialComments: 33 pages, 15 figures, Results extended to include a dip in the potential, Additional comments and references, Accepted for publication in JCAPSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [77] arXiv:1912.00616 (replaced) [pdf, other]
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Title: Revisiting pre-inflationary universe of family of $α-$attractor in loop quantum cosmologyComments: 18 pages, 6 caption figures, 4 tables, typos correctedSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [78] arXiv:1912.02415 (replaced) [pdf, other]
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Title: Modelling Double Neutron Stars: Radio and Gravitational WavesComments: 26 pages, Accepted for publication by MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [79] arXiv:1912.07065 (replaced) [pdf, other]
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Title: Primordial backgrounds of relic gravitonsAuthors: Massimo GiovanniniComments: 147 pages, 23 figures; corrected typos, discussions and references addedJournal-ref: Prog.Part.Nucl.Phys. (2020) 103774Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [80] arXiv:1912.07586 (replaced) [pdf, other]
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Title: Phenomenology of the generalized cubic covariant Galileon model and cosmological boundsComments: 13 pages, 10 figures, 3 tablesJournal-ref: Phys. Rev. D 101, 064001 (2020)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [81] arXiv:1912.08560 (replaced) [pdf, other]
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Title: Stable Cosmology in Generalised Massive GravityComments: 13 pages, 2 figures. V2: Typos corrected, sentences added. Accepted for publication in PRDSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [82] arXiv:2001.01932 (replaced) [pdf, ps, other]
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Title: The mean tilt of sunspot bipolar regions: theory, simulations and comparison with observationsComments: 12 pages, 4 figures, mn2e.cls , revisedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)
- [83] arXiv:2001.06926 (replaced) [pdf, other]
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Title: Supernova Magnitude Evolution and PAge ApproximationAuthors: Zhiqi HuangComments: ApJL acceptedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [84] arXiv:2001.09153 (replaced) [pdf, other]
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Title: Magnetohydrodynamic Simulations of Binary Neutron Star Mergers in General Relativity: Effects of Magnetic Field Orientation on Jet LaunchingComments: 16 pages, 12 figures. Matches published versionJournal-ref: Phys.Rev.D 101, 064042 (2020)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [85] arXiv:2002.09257 (replaced) [pdf, other]
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Title: Gas fractions and depletion times in galaxies with different degrees of interactionComments: Accepted for publication in A&A (February 21, 2020). 6 pages, 5 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [86] arXiv:2002.10331 (replaced) [pdf, ps, other]
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Title: Black Hole as a Quantum Field ConfigurationComments: ver2: Clarification of subsections 3.1, 3.2, 8.5 and 9.1 without changing the main results, references added, and other minor modificationsSubjects: High Energy Physics - Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [87] arXiv:2002.11871 (replaced) [pdf]
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Title: Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens MissionAuthors: Slava G. Turyshev, Michael Shao, Viktor T. Toth, Louis D. Friedman, Leon Alkalai, Dmitri Mawet, Janice Shen, Mark R. Swain, Hanying Zhou, Henry Helvajian, Tom Heinsheimer, Siegfried Janson, Zigmond Leszczynski, John McVey, Darren Garber, Artur Davoyan, Seth Redfield, Jared R. MalesComments: Final Report for the NASA's Innovative Advanced Concepts (NIAC) Phase II proposal. 91 pages, 50 figures, 5 tablesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); General Relativity and Quantum Cosmology (gr-qc); Optics (physics.optics)
- [88] arXiv:2002.12712 (replaced) [pdf, other]
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Title: TNOs are Cool! A Survey of the transneptunian Region XV. Physical characteristics of 23 resonant transneptunian and scattered disk objectsAuthors: A. Farkas-Takács, Cs. Kiss, E. Vilenius, G. Marton, T.G. Müller, M. Mommert, J. Stansberry, E. Lellouch, P. Lacerda, A. PálComments: Accepted for publication in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [89] arXiv:2003.03059 (replaced) [pdf, ps, other]
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Title: Magnetic field structure of the Galactic plane from differential analysis of interstellar polarizationAuthors: Tetsuya Zenko, Tetsuya Nagata, Mikio Kurita, Masaru Kino, Shogo Nishiyama, Noriyuki Matsunaga, Yasushi NakajimaComments: 32 pages, 17 figures, accepted in PASJSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [90] arXiv:2003.06012 (replaced) [pdf, other]
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Title: Multi-Frequency Observations of the Candidate Neutrino Emitting Blazar BZB J0955+3551Authors: Vaidehi S. Paliya, M. Böttcher, A. Olmo-García, A. Domínguez, A. Gil de Paz, A. Franckowiak, S. Garrappa, R. SteinComments: Submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [91] arXiv:2003.06223 (replaced) [pdf, other]
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Title: The Fraction of Gamma-ray Bursts with an Observed Photospheric Emission EpisodeComments: Accepted: ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [92] arXiv:2003.08092 (replaced) [pdf, other]
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Title: The determination of stellar temperatures from Baron B. Harkányi to the Gaia missionAuthors: Kristof PetrovayComments: 10 pages, 2 figures, 1 table. Journal for the History of Astronomy, in press (May 2020 issue)Subjects: History and Philosophy of Physics (physics.hist-ph); Solar and Stellar Astrophysics (astro-ph.SR)
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