Astrophysics
New submissions
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New submissions for Fri, 22 Nov 19
- [1] arXiv:1911.09110 [pdf, other]
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Title: Neutrino propagation hinders fast pairwise flavor conversionsComments: 19 pages, 10 figures, Animated visualizations available at this https URLSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Neutrino flavor conversions may dramatically affect the inner working of compact astrophysical objects as well as the synthesis of new elements. We present the first sophisticated numerical solution of the neutrino flavor conversion within a (2+1+1) dimensional setup: we include the advective term in the neutrino equations of motion and track the flavor evolution in two spatial dimensions, one angular variable, and time. Notably, the advective term hinders the development of neutrino pairwise conversions, if the conditions favoring such conversions (i.e., crossings between the angular distributions of $\nu_e$ and $\bar\nu_e$ or a non-negligible flux of neutrinos traveling backward with respect to the main propagation direction) exist for time scales shorter than the typical time scale of the advective term. As a consequence, fast pairwise conversions can only occur when the conditions favoring flavor conversions are self-sustained and global, such as the ones induced by the lepton emission self-sustained asymmetry (LESA) in core-collapse supernovae. Our work highlights the major impact of the dynamical evolution of the neutrino field on the growth of flavor instabilities and the strong interplay between classical and quantum effects. Critical limitations of the linear stability analysis, used to predict neutrino flavor instabilities, are also pointed out.
- [2] arXiv:1911.09112 [pdf, other]
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Title: Core-collapse, superluminous, and gamma-ray burst supernova host galaxy populations at low redshift: the importance of dwarf and starbursting galaxiesComments: 30 pages, 11 figures. Submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present a comprehensive study of an unbiased sample of 84 nearby (<z> = 0.018) core-collapse supernova (CCSN) host galaxies drawn from the All-Sky Automated Survey for Supernovae (ASAS-SN) for direct comparison to the nearest LGRB and SLSN hosts. We use public imaging surveys to gather multi-wavelength photometry for all CCSN host galaxies and fit their spectral energy distributions (SEDs) to derive stellar masses and integrated star formation rates. CCSNe populate galaxies across a wide range of stellar masses, from blue and compact dwarf galaxies to large spiral galaxies. We find 40(+6,-5) per cent of CCSNe are in dwarf galaxies (M < 10^9 M_Sun) and 2(+3,-1) per cent are in dwarf starburst galaxies (sSFR > 10^-8 yr^-1). We reanalyse the low-redshift SLSN and LGRB hosts from the literature (out to z < 0.3) in a homogeneous way and compare against the CCSN host sample. We find that the relative SLSN to CCSN supernova rate is increased in low-mass galaxies and at high specific star-formation rates. These parameters are strongly covariant and we cannot break the degeneracy between them with our current sample. Larger unbiased samples of CCSNe from projects such as ZTF and LSST will be needed to determine whether host-galaxy mass (a proxy for metallicity) or specific star-formation rate (a proxy for star-formation intensity and potential IMF variation) is more fundamental in driving the preference for SLSNe and LGRBs in unusual galaxy environments.
- [3] arXiv:1911.09113 [pdf, other]
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Title: The Role of Quasar Radiative Feedback on Galaxy Formation during Cosmic ReionizationAuthors: Huanqing ChenComments: 13 pages, 14 figures, comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Recent observations have found that many $z\sim 6$ quasar fields lack galaxies. This unexpected lack of galaxies may potentially be explained by quasar radiation feedback. In this paper I present a suite of 3D radiative transfer cosmological simulations of quasar fields. I find that quasar radiation suppresses star formation in low mass galaxies, mainly by photo-dissociating their molecular hydrogen. Photo-heating also plays a role, but only after $\sim$100 Myr. However, galaxies which already have stellar mass above $10^5 M_\odot$ when the quasar turns on will not be suppressed significantly. Quasar radiative feedback suppresses the faint end of the galaxy luminosity function (LF) within $1$ pMpc, but to a far lesser degree than the field-to-field variation of the LF. My study also suggests that by using the number of bright galaxies ($M_{1500}<-16$) around quasars, we can potentially recover the underlying mass overdensity, which allows us to put reliable constraints on quasar environments.
- [4] arXiv:1911.09114 [pdf, other]
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Title: Multivariate Time-series Analysis of Variable Objects in the Gaia MissionAuthors: Laurent Eyer, Maria Süveges, Joris De Ridder, Sara Regibo, Nami Mowlavi, Berry Holl, Lorenzo Rimoldini, Francois BouchyComments: Published in PASP, 12 pages, 5 figuresJournal-ref: Publications of the Astronomical Society of the Pacific, Volume 131, Issue 1002, pp. 088001 (2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
In astronomy, we are witnessing an enormous increase in the number of source detections, precision, and diversity of measurements. Additionally, multi-epoch data is becoming the norm, making time-series analyses an important aspect of current astronomy. The Gaia mission is an outstanding example of a multi-epoch survey that provides measurements in a large diversity of domains, with its broad-band photometry; spectrophotometry in blue and red (used to derive astrophysical parameters); spectroscopy (employed to infer radial velocities, v sin(i), and other astrophysical parameters); and its extremely precise astrometry. Most of all that information is provided for sources covering the entire sky. Here, we present several properties related to the Gaia time series, such as the time sampling; the different types of measurements; the Gaia G, G BP and G RP-band photometry; and Gaia-inspired studies using the CORrelation-RAdial-VELocities data to assess the potential of the information on the radial velocity, the FWHM, and the contrast of the cross-correlation function. We also present techniques (which are used or are under development) that optimize the extraction of astrophysical information from the different instruments of Gaia, such as the principal component analysis and the multi-response regression. The detailed understanding of the behavior of the observed phenomena in the various measurement domains can lead to richer and more precise characterization of the Gaia data, including the definition of more informative attributes that serve as input to (our) machine-learning algorithms.
- [5] arXiv:1911.09116 [pdf, other]
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Title: Baryonic clues to the puzzling diversity of dwarf galaxy rotation curvesAuthors: Isabel M.E. Santos-Santos, Julio F. Navarro, Andrew Robertson, Alejandro Benítez-Llambay, Kyle A. Oman, Mark R. Lovell, Carlos S. Frenk, Aaron D. Ludlow, Azadeh Fattahi, Adam RitzComments: 16 pages, 14 figures, 1 table. Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We use a sample of galaxies with high-quality rotation curves to assess the role of the luminous component ("baryons") in the dwarf galaxy rotation curve diversity problem. As in earlier work, we find that the shape of the rotation curve correlates with baryonic surface density; high surface density galaxies have rapidly-rising rotation curves consistent with cuspy cold dark matter halos, slowly-rising rotation curves (characteristic of galaxies with inner mass deficits or "cores") occur only in low surface density galaxies. The correlation, however, seems too weak in the dwarf galaxy regime to be the main driver of the diversity. In particular, the observed dwarf galaxy sample includes "cuspy" systems where baryons are unimportant in the inner regions and "cored" galaxies where baryons actually dominate the inner mass budget. These features are important diagnostics of the viability of various scenarios proposed to explain the diversity, such as (i) baryonic inflows and outflows; (ii) dark matter self-interactions (SIDM); (iii) variations in the baryonic acceleration through the "mass discrepancy-acceleration relation" (MDAR); or (iv) non-circular motions in gaseous discs. A reanalysis of existing data shows that MDAR does not hold in the inner regions of dwarf galaxies and thus cannot explain the diversity. Together with analytical modeling and cosmological hydrodynamical simulations, our analysis shows that each of the remaining scenarios has promising features, but none seems to fully account for the observed diversity. The origin of the dwarf galaxy rotation curve diversity and its relation to the small structure of cold dark matter remains an open issue.
- [6] arXiv:1911.09120 [pdf, other]
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Title: Searching for Sterile Neutrino with X-ray Intensity MappingComments: 21 pages, 6 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
The cosmological X-ray emission associated to the possible radiative decay of sterile neutrinos is composed by a collection of lines at different energies. For a given mass, each line corresponds to a given redshift. In this work, we cross correlate such line emission with catalogs of galaxies tracing the dark matter distribution at different redshifts. We derive observational prospects by correlating the X-ray sky that will be probed by the eROSITA and Athena missions with current and near future photometric and spectroscopic galaxy surveys. A relevant and unexplored fraction of the parameter space of sterile neutrinos can be probed by this technique.
- [7] arXiv:1911.09121 [pdf, ps, other]
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Title: Complementarity of Peculiar Velocity Surveys and Redshift Space Distortions for Testing GravityComments: 6 pages, 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Peculiar-velocity surveys of the low-redshift universe have significant leverage to constrain the growth rate of cosmic structure and test gravity. Wide-field imaging surveys combined with multi-object spectrographs (e.g. ZTF2, LSST, DESI, 4MOST) can use Type Ia supernovae as informative tracers of the velocity field, reaching few percent constraints on the growth rate $f\sigma_8$ at $z\lesssim0.2$ where density tracers cannot do better than $\sim10\%$. Combining the high-redshift DESI survey mapping redshift space distortions with a low-redshift supernova peculiar velocity survey using LSST and DESI can determine the gravitational growth index to $\sigma(\gamma)\approx0.02$, testing general relativity. We study the characteristics needed for the peculiar velocity survey, and how its complementarity with clustering surveys improves when going from a $\Lambda$CDM model assumption to a $w_0$-$w_a$ cosmology.
- [8] arXiv:1911.09124 [pdf, other]
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Title: To beta or not to beta: can higher-order Jeans analysis break the mass-anisotropy degeneracy in simulated dwarfs?Authors: Anna Genina, Justin I. Read, Carlos S. Frenk, Shaun Cole, Alejandro Benitez-Llambay, Aaron D. Ludlow, Julio F. Navarro, Kyle A. Oman, Andrew RobertsonComments: 17 pages, 9 figures. Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
A non-parametric higher-order Jeans analysis method, GravSphere, was recently used to constrain the density profiles of Local Group dwarf galaxies, classifying them into those that are more likely to have an inner dark matter cusp and those that are likely to have a core (Read et al.). In this work we test this method using 31 simulated galaxies, comparable to Fornax, selected from the APOSTLE suite of cosmological hydrodynamics simulations, which include CDM and Self-Interacting Dark Matter (SIDM) cosmologies. We find that the mass profiles of the simulated dwarfs are often, but not always, well recovered by GravSphere. The less successful cases may be identified using a chi-squared diagnostic. Although the uncertainties are large in the inner regions, the inferred mass profiles are unbiased and exhibit smaller scatter than comparable Jeans methods. We find that GravSphere recovers the density profiles of simulated dwarfs below the half-light radius and down to the resolution limit of our simulations with better than 10+-30 per cent accuracy, making it a promising Jeans-based approach for modelling dark matter distributions in dwarf galaxies.
- [9] arXiv:1911.09125 [pdf, other]
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Title: A Dynamical Survey of Stellar-Mass Black Holes in 50 Milky Way Globular ClustersComments: 25 pages, 8 figures, 6 tables, submitted to ApJ. Comments welcomeSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Recent numerical simulations of globular clusters (GCs) have shown that stellar-mass black holes (BHs) play a fundamental role in driving cluster evolution and shaping their present-day structure. Rapidly mass-segregating to the center of GCs, BHs act as a dynamical energy source via repeated super-elastic scattering, delaying onset of core collapse and limiting mass segregation for visible stars. While recent discoveries of BH candidates in Galactic and extragalactic GCs have further piqued interest in BH-mediated cluster dynamics, numerical models show that even if significant BH populations remain in today's GCs, they are typically in configurations that are not directly detectable. We demonstrated in Weatherford et al. (2018) that an anti-correlation between a suitable measure of mass segregation ($\Delta$) in observable stellar populations and the number of retained BHs in GC models can be applied to indirectly probe BH populations in real GCs. Here, we estimate the number and total mass of BHs presently retained in 50 Milky Way GCs from the ACS Globular Cluster Survey by measuring $\Delta$ between populations of main sequence stars, using correlations found between $\Delta$ and BH retention in the CMC Cluster Catalog models. We demonstrate that the range in $\Delta$'s distribution from our models matches that for observed GCs to a remarkable degree. Our results further provide the narrowest constraints to-date on the retained BH populations in the GCs analyzed. Of these 50 GCs, we identify NGCs 2808, 5927, 5986, 6101, and 6205 to presently contain especially large BH populations, each with total BH mass exceeding $10^3\,\rm{M_{\odot}}$.
- [10] arXiv:1911.09131 [pdf, other]
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Title: The Orbit of WASP-12b is DecayingAuthors: Samuel W. Yee, Joshua N. Winn, Heather A. Knutson, Kishore C. Patra, Shreyas Vissapragada, Michael M. Zhang, Matthew J. Holman, Avi Shporer, Jason T. WrightComments: 16 pages, 6 tables, 5 figures, accepted to AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
WASP-12b is a transiting hot Jupiter on a 1.09-day orbit around a late-F star. Since the planet's discovery in 2008, the time interval between transits has been decreasing by $29\pm 2$ msec year$^{-1}$. This is a possible sign of orbital decay, although the previously available data left open the possibility that the planet's orbit is slightly eccentric and is undergoing apsidal precession. Here, we present new transit and occultation observations that provide more decisive evidence for orbital decay, which is favored over apsidal precession by a $\Delta\mathrm{BIC}$ of 22.3 or Bayes factor of 70,000. We also present new radial-velocity data that rule out the R{\o}mer effect as the cause of the period change. This makes WASP-12 the first planetary system for which we can be confident that the orbit is decaying. The decay timescale for the orbit is $P/\dot{P} = 3.25\pm 0.23$ Myr. Interpreting the decay as the result of tidal dissipation, the modified stellar tidal quality factor is $Q'_\star = 1.8 \times10^{5}$.
- [11] arXiv:1911.09132 [pdf, other]
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Title: A mirage of the cosmic shoreline: Venus-like clouds as a statistical false positive for exoplanet atmospheric erosionComments: 13 pages, 4 figures, accepted for publication in ApJ LettersSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Near-term studies of Venus-like atmospheres with JWST promise to advance our knowledge of terrestrial planet evolution. However, the remote study of Venus in the Solar System and the ongoing efforts to characterize gaseous exoplanets both suggest that high altitude aerosols could limit observational studies of lower atmospheres, and potentially make it challenging to recognize exoplanets as "Venus-like". To support practical approaches for exo-Venus characterization with JWST, we use Venus-like atmospheric models with self-consistent cloud formation of the seven TRAPPIST-1 exoplanets to investigate the atmospheric depth that can be probed using both transmission and emission spectroscopy. We find that JWST/MIRI LRS secondary eclipse emission spectroscopy in the 6 $\mu$m opacity window could probe at least an order of magnitude deeper pressures than transmission spectroscopy, potentially allowing access to the sub-cloud atmosphere for the two hot innermost TRAPPIST-1 planets. In addition, we identify two confounding effects of sulfuric acid aerosols that may carry strong implications for the characterization of terrestrial exoplanets with transmission spectroscopy: (1) there exists an ambiguity between cloud-top and solid surface in producing the observed spectral continuum; and (2) the cloud-forming region drops in altitude with semi-major axis, causing an increase in the observable cloud-top pressure with decreasing stellar insolation. Taken together, these effects could produce a trend of thicker atmospheres observed at lower stellar insolation---a convincing false positive for atmospheric escape and an empirical "cosmic shoreline". However, developing observational and theoretical techniques to identify Venus-like exoplanets and discriminate them from stellar windswept worlds will enable advances in the emerging field of terrestrial comparative planetology.
- [12] arXiv:1911.09138 [pdf, ps, other]
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Title: Large Scale Distribution of Galaxies in The Field HS 47.5-22. I. Data Analysis TechniqueComments: Accepted for publication in Astrophysical Bulletin, 9 pages, 8 figures, 1 tableSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present the results of methodological works on automated analysis of the large scale distribution of galaxies. Selecting candidates for clusters and groups of galaxies was carried out using two complementary methods of determining the density contrast maps in the narrow layers of the three-dimensional large scale distribution of galaxies: the filtering algorithm with an adaptive core and the Voronoi tesselation. The developed algorithms were tested on 10 data sets of the MICE model catalog; additionally, we determined the statistical parameters of the obtained results (completeness, sample purity, etc.). The constructed density contrast maps were also used to determine voids.
- [13] arXiv:1911.09147 [pdf, other]
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Title: Quantum magnetic collapse of a partially bosonized npe-gas: Implications for astrophysical jetsComments: 10 pages, 11 figures and one appendixSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We study a possible mechanism for astrophysical jet production from a neutron star composed by a partially bosonized npe-gas. We obtain that the expulsion of a stable stream of matter might be triggered by the quantum magnetic collapse of one or various components of the gas, while its collimation is due to the formation of a strong self-generated magnetic field.
- [14] arXiv:1911.09167 [pdf, other]
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Title: A dwarf-dwarf merger and dark matter core as a solution to the Globular Cluster problems in the Fornax dSphComments: 18 pages, 15 figures, accepted by MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
The five globular clusters (GCs) of the Fornax dSph are puzzling for two reasons; the mass in GCs is high with respect to the galaxy's old stellar mass, and their survival and large distance (> 1 kpc) is at odds with naive expectations of dynamical friction. We present here a semi-analytic model, simultaneously addressing both problems in a comprehensive evolutionary framework for Fornax. Key to the model is inclusion of: 1) hydrodynamical constraints on the GC formation locations, 2) self-consistent velocity distribution functions in the dynamical friction calculations and 3) expansion of GC orbits due to a past dwarf-dwarf merger in the orbit integrations. The latter is crucial for reconciling the dynamical survival of the clusters, and their chemical properties with respect to the Fornax field stars. We find that in order for four of the GCs to survive at their observed projected location, a dark matter core of radius > 1.5 kpc and a dwarf merger with dynamical mass ratio of 1:5 to 1:2 with Fornax is required. We support the merger scenario by showing that aspects of the field star metallicity distribution function and anomalous chemical properties of GC5, are representative of a merging galaxy which is ~1/3 less massive than Fornax. Together the chemical and dynamical models suggest a scenario where three in-situ GCs in proto-Fornax were ejected to the outskirts during the merger, a GC4 formed during the merger at about 10 Gyrs ago, with GC5 being brought in by the merging galaxy to Fornax.
- [15] arXiv:1911.09181 [pdf, other]
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Title: The GOES-R EUVS Model for EUV Irradiance VariabilityAuthors: E. M. B. Thiemann, F. G. Eparvier, D. Woodraska, P. C. Chamberlin, J. Machol, T. Eden, A. R. Jones, R. Meisner, S. Mueller, M. Snow, R. Viereck, T. N. WoodsComments: Accepted by Journal of Space Weather and Space Climate on 20 November 2019Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
The Geostationary Operational Environmental Satellite R (GOES-R) series of four satellites are the next generation NOAA GOES satellites. Once on orbit and commissioned, they are renamed GOES 16-19, making critical terrestrial and space weather measurements through 2035. GOES 16 and 17 are currently on orbit, having been launched in 2016 and 2018, respectively. The GOES-R satellites include the EUV and X-ray Irradiance Sensors (EXIS) instrument suite, which measures calibrated solar irradiance in 8 lines or bands between 25 and 285 nm with the Extreme Ultraviolet Sensors (EUVS) instrument. EXIS also includes the X-Ray Sensor (XRS) instrument, which measures solar soft X-ray irradiance at the legacy GOES bands. The EUVS measurements are used as inputs to the EUVS Model, a solar spectral irradiance model for space weather operations that predicts irradiance in twenty-two 5 nm wide intervals from 5 nm to 115 nm, and one 10 nm wide interval from 117 to 127 nm at 30 second cadence. Once fully operational, NOAA will distribute the EUVS Model irradiance with 1 minute latency as a primary space weather data product, ushering in a new era of rapid dissemination and measurement continuity of EUV irradiance spectra. This paper describes the EUVS Model algorithms, data sources, calibration methods and associated uncertainties. Typical model (relative) uncertainties are less than $\sim$5\% for variability at time-scales longer than 6 hours, and are $\sim$25\% for solar flare induced variability. The absolute uncertainties, originating from the instruments used to calibrate the EUVS Model, are $\sim$10\%. Examples of model results are presented at both sub-daily and multi-year timescales to demonstrate the model's capabilities and limitations. Example solar flare irradiances are also modeled.
- [16] arXiv:1911.09183 [pdf, other]
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Title: Line Driven Acceleration using Multi-Frequency Radiation HydrodynamicsComments: 10 pages, 6 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
We use multi-frequency radiation hydrodynamics (rad-HD) to simulate radiative acceleration of a spherically symmetric stellar wind. We demonstrate the rad-HD capabilities of Athena++ for a series of test problems with multi-group radiation transfer. We then model the radiative transfer of a single spectral line through a spherically symmetric, isothermal, "CAK"-type line driven wind. We find that correctly accounting for the Doppler shift of the absorbed radiation, the force is well described by the analytic Sobolev line transfer in the supersonic parts of the solution where the flow is stationary and the effects of Abbott waves is negligible. Unlike in the analytic, steady-state solution re-radiation is important and leads to non-trivial radiation energy density and fluxes in the outer parts of the wind. We discuss a variety of applications to these multi-group methods that are currently computationally tractable.
- [17] arXiv:1911.09187 [pdf, other]
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Title: The ISM scaling relations in DustPedia late-type galaxies: a benchmark study for the Local UniverseAuthors: Viviana Casasola, Simone Bianchi, Pieter De Vis, Laura Magrini, Edvige Corbelli, Christopher J. R. Clark, Jacopo Fritz, Angelos Nersesian, Sebastien Viaene, Maarten Baes, Letizia P. Cassara', Jon Davies, Ilse De Looze, Wouter Dobbels, Maud Galametz, Frederic Galliano, Anthony P. Jones, Suzanne C. Madden, Aleksandr V. Mosenkov, Ana Trcka, Emmanuel XilourisComments: Accepted for publication in A&A, 21 pages, 14 Figures, 7 Tables, 2 Appendices (with 3 Tables)Subjects: Astrophysics of Galaxies (astro-ph.GA)
The purpose of this work is the characterization of the main scaling relations between all the ISM components (dust, atomic/molecular/total gas), gas-phase metallicity, and other galaxy properties, such as Mstar and galaxy morphology, for late-type galaxies in the Local Universe. This study is performed by extracting late-type galaxies from the entire DustPedia sample and by exploiting the large and homogeneous dataset available thanks to the DustPedia project. The sample consists of 436 galaxies with morphological stage from T = 1 to 10, Mstar from 6 x 10^7 to 3 x 10^11 Msun, SFR from 6 x 10^(-4) to 60 Msun/yr, and 12 + log(O/H) from 8 to 9.5. The scaling relations involving the molecular gas are studied by assuming both a constant and a metallicity-dependent XCO. The analysis has been performed by means of the survival analysis technique. We confirm that the dust mass correlates very well with the total gas mass, and find -- for the first time -- that the dust mass correlates better with the atomic gas mass than the molecular one. We characterize important mass ratios such as gas fraction, molecular-to-atomic gas mass ratio, dust-to-total gas mass ratio (DGR), and dust-to-stellar mass ratio. Only the assumption of a metallicity-dependent XCO reproduces the expected decrease of the DGR with increasing morphological stage and decreasing gas-phase metallicity, with a slope of about 1. DGR, gas-phase metallicity, and the dust-to-stellar mass ratio are, for our galaxy sample, directly linked to the galaxy morphology. The molecular-to-atomic gas mass ratio and the DGR show a positive correlation for low molecular gas fractions, but for molecular gas rich galaxies this trend breaks down. This trend has never been found previously, to our knowledge. It provides new constraints for theoretical models of galaxy evolution and a reference for high-redshift studies.
- [18] arXiv:1911.09211 [pdf, other]
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Title: Detecting and Characterizing Water Vapor in the Atmospheres of Earth Analogs through Observation of the 0.94 Micron Feature in Reflected LightAuthors: Adam J. R. W. Smith, Y. Katherina Feng, Jonathan J. Fortney, Tyler D. Robinson, Mark S. Marley, Roxana E. Lupu, Nikole K. LewisComments: Accepted to AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
The characterization of rocky, Earth-like planets is an important goal for future large ground- and space-based telescopes. In support of developing an efficient observational strategy, we have applied Bayesian statistical inference to interpret the albedo spectrum of cloudy true-Earth analogs that include a diverse spread in their atmospheric water vapor mixing ratios. We focus on detecting water-bearing worlds by characterizing their atmospheric water vapor content via the strong 0.94$\,\mu$m H$_2$O absorption feature, with several observational configurations. Water vapor is an essential signpost when assessing planetary habitability, and determining its presence is important in vetting whether planets are suitable for hosting life. We find that R=140 spectroscopy of the absorption feature combined with a same-phase green optical photometric point at $0.525-0.575\,\mu$m is capable of distinguishing worlds with less than $0.1\times$ Earth-like water vapor levels from worlds with $1\times$ Earth-like levels or greater at a signal-to-noise ratio of 5 or better with $2\sigma$ confidence. This configuration can differentiate between $0.01\times$ and $0.1\times$ Earth-like levels when the signal-to-noise ratio is 10 or better at the same confidence. However, strong constraints on the water vapor mixing ratio remained elusive with this configuration even at signal-to-noise of 15. We find that adding the same-phase optical photometric point does not significantly help characterize the H$_2$O mixing ratio, but does enable an upper limit on atmospheric ozone levels. Finally, we find that a 0.94$\,\mu$m photometric point, instead of spectroscopy, combined with the green-optical point, fails to produce meaningful information about atmospheric water content.
- [19] arXiv:1911.09236 [pdf, other]
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Title: Active gas features in three HSC-SSP CAMIRA clusters revealed by high angular resolution analysis of MUSTANG-2 SZE and XXL X-ray observationsAuthors: Nobuhiro Okabe, Simon Dicker, Dominique Eckert, Tony Mroczkowski, Fabio Gastaldello, Yen-Ting Lin, Mark Devlin, Charles E. Romero, Mark Birkinshaw, Craig Sarazin, Cathy Horellou, Tetsu Kitayama, Keiichi Umetsu, Mauro Sereno, Brian S. Mason, John A. ZuHone, Ayaka Honda, Hiroki Akamatsu, I-Non Chiu, Kotaro Kohno, Kai-Yang Lin, Elinor Medezinski, Satoshi Miyazaki, Ikuyuki Mitsuishi, Atsushi J. Nishizawa, Masamune Oguri, Naomi Ota, Florian Pacaud, Marguerite Pierre, Jonathan Sievers, Vernesa Smolcic, Sara Stanchfield, Keigo Tanaka, Ryoichi Yamamoto, Chong Yang, Atsushi YoshidaComments: 32 pages, 25 figures, 4 tables, submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present results from simultaneous modeling of high angular resolution GBT/MUSTANG-2 90 GHz Sunyaev-Zel'dovich effect (SZE) measurements and XMM-XXL X-ray images of three rich galaxy clusters selected from the HSC-SSP Survey. The combination of high angular resolution SZE and X-ray imaging enables a spatially resolved multi-component analysis, which is crucial to understand complex distributions of cluster gas properties. The targeted clusters have similar optical richnesses and redshifts, but exhibit different dynamical states in their member galaxy distributions; a single-peaked cluster, a double-peaked cluster, and a cluster belonging to a supercluster. A large-scale residual pattern in both regular Compton-parameter $y$ and X-ray surface brightness distributions is found in the single-peaked cluster, indicating a sloshing mode. The double-peaked cluster shows an X-ray remnant cool core between two SZE peaks associated with galaxy concentrations. The temperatures of the two peaks reach $\sim20-30$ keV in contrast to the cool core component of $\sim2$ keV, indicating a violent merger. The highest SZE signal for the supercluster is elongated along a direction perpendicular to the major axis of the X-ray core, suggesting a minor merger before core passage. The $S_X$ and $y$ distributions are thus perturbed at some level, regardless of the optical properties. We find that an integrated Compton $y$ parameter and a temperature for the major merger are significantly boosted from those expected by the weak-lensing mass and those for the other two clusters show no significant deviations, which is consistent with predictions of numerical simulations.
- [20] arXiv:1911.09261 [pdf, other]
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Title: Supernova ejecta interacting with a circumstellar disk. I. two-dimensional radiation-hydrodynamic simulationsComments: 35 pages, 22 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We perform a series of two-dimensional radiation-hydrodynamic simulations of the collision between supernova ejecta and circumstellar media (CSM). The hydrodynamic interaction of a fast flow and the surrounding media efficiently dissipates the kinetic energy of the fast flow and considered as a dominant energy source for a specific class of core-collapse supernovae. Despite some observational evidence for aspherical ejecta and/or CSM structure, multi-dimensional effects in the ejecta-CSM interaction are relatively unexplored. Our numerical simulations equipped with an adaptive mesh refinement technique successfully reproduce hydrodynamic instabilities developing around the ejecta-CSM interface. We also investigate effects of disk-like CSM on the dynamical evolution of supernova ejecta and bolometric light curves. We find that emission powered by ejecta-disk interaction exhibits significant viewing angle dependence. For a line of sight close to the symmetry axis, the observer directly sees the supernova ejecta, leading to a short brightening timescale. For an observer seeing the emission through the CSM disk, thermal photons diffuse throughout the CSM and thus the light curve is severely smeared out.
- [21] arXiv:1911.09270 [pdf]
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Title: An optical test bench for the precision characterization of absolute quantum efficiency for the TESS CCD detectorsJournal-ref: Journal of Instrumentation, Volume 12, May 2017Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright stars with Ic<13. TESS has been selected by NASA for launch in 2018 as an Astrophysics Explorer mission, and is expected to discover a thousand or more planets that are smaller in size than Neptune. TESS will employ four wide-field optical charge-coupled device (CCD) cameras with a band-pass of 650 nm-1050 nm to detect temporary drops in brightness of stars due to planetary transits. The 1050 nm limit is set by the quantum efficiency (QE) of the CCDs. The detector assembly consists of four back-illuminated MIT Lincoln Laboratory CCID-80 devices. Each CCID-80 device consists of 2048x2048 imaging array and 2048x2048 frame store regions. Very precise on-ground calibration and characterization of CCD detectors will significantly assist in the analysis of the science data obtained in space. The characterization of the absolute QE of the CCD detectors is a crucial part of the characterization process because QE affects the performance of the CCD significantly over the redder wavelengths at which TESS will be operating. An optical test bench with significantly high photometric stability has been developed to perform precise QE measurements. The design of the test setup along with key hardware, methodology, and results from the test campaign are presented.
- [22] arXiv:1911.09295 [pdf, other]
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Title: How Accurately Can We Detect the Splashback Radius of Dark Matter Halos and its Correlation With Accretion Rate?Authors: Enia Xhakaj, Benedikt Diemer, Alexie Leauthaud, Asher Wasserman, Song Huang, Yifei Luo, Susmita Adhikari, Sukhdeep SinghSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The splashback radius ($R_{\rm sp}$) of dark matter halos has recently been detected using weak gravitational lensing and cross-correlations with galaxies. However, different methods have been used to measure $R_{\rm sp}$ and to assess the significance of its detection. In this paper, we use simulations to study the precision and accuracy to which we can detect the splashback radius with 3D density, 3D subhalo, and weak lensing profiles. We study how well various methods and tracers recover $R_{\rm sp}$ by comparing it with the value measured directly from particle dynamics. We show that estimates of $R_{\rm sp}$ from density and subhalo profiles correspond to different percentiles of the underlying $R_{\rm sp}$ distribution of particle orbits. At low accretion rates, a second caustic appears and can bias results. Finally, we show that upcoming lensing surveys may be able to constrain the splashback-accretion rate relation directly.
- [23] arXiv:1911.09342 [pdf, other]
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Title: MusE GAs FLOw and Wind (MEGAFLOW) IV: A two sightline tomography of a galactic windAuthors: Johannes Zabl, Nicolas F. Bouché, Ilane Schroetter, Martin Wendt, Thierry Contini, Joop Schaye, Raffaella A. Marino, Sowgat Muzahid, Gabriele Pezzulli, Anne Verhamme, Lutz WisotzkiComments: Submitted to MNRAS. After addressing referee's commentsSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Galactic outflows are thought to eject baryons back out to the circum-galactic medium (CGM). Studies based on metal absorption lines (MgII in particular) in the spectra of background quasars indicate that the gas is ejected anisotropically, with galactic winds likely leaving the host in a bi-conical flow perpendicular to the galaxy disk. In this paper, we present a detailed analysis of an outflow from a z = 0.7 "green-valley" galaxy (log($M_*$/$\mathrm{M}_\odot$) = 9.9; SFR = 0.5 $\mathrm{M}_\odot\,\mathrm{yr}^{-1}$) probed by two background sources part of the MUSE Gas Flow and Wind (MEGAFLOW) survey. Thanks to a fortuitous configuration with a background quasar (SDSSJ1358+1145) and a bright background galaxy at $z = 1.4$, both at impact parameters of $\approx 15\,\mathrm{kpc}$, we can - for the first time - probe both the receding and approaching components of a putative galactic outflow around a distant galaxy. We measure a significant velocity shift between the MgII absorption from the two sightlines ($84\pm17\,\mathrm{km}\,\mathrm{s}^{-1}$), which is consistent with the expectation from our simple fiducial wind model, possibly combined with an extended disk contribution.
- [24] arXiv:1911.09353 [pdf]
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Title: AMBRE: A Compact Instrument to Measure Thermal Ions, Electrons and Electrostatic Charging Onboard SpacecraftAuthors: B. Lavraud (IRAP), A. Cara, D. Payan (CNES), Y. Ballot, J.-A. Sauvaud (CESR), R. Mathon, T. Camus (CESR), O. Chassela (IRAP), H.-C. Seran, H. Tap, O. Bernal, M. Berthomier (CETP), P. Devoto, A. Fedorov (IKI), J. Rouzaud (CESR), J. Rubiella-Romeo, J.-D Techer, D. Zely, S. Galinier, D. BrunoJournal-ref: 2019 ESA Workshop on Aerospace EMC (Aerospace EMC), May 2019, Budapest, Hungary. pp.1-5Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
The Active Monitor Box of Electrostatic Risks (AMBER) is a double-head thermal electron and ion electrostatic analyzer (energy range 0-30 keV) that was launched onboard the Jason-3 spacecraft in 2016. The next generation AMBER instrument, for which a first prototype was developed and then calibrated at the end of 2017, constitutes a significant evolution that is based on a single head to measure both species alternatively. The instrument developments focused on several new subsystems (front-end electronics, high-voltage electronics, mechanical design) that permit to reduce instrument resources down to ~ 1 kg and 1.5 W. AMBER is designed as a generic radiation monitor with a twofold purpose: (1) measure magnetospheric thermal ion and electron populations in the range 0-35 keV, with significant scientific potential (e.g., plasmasphere, ring current, plasma sheet), and (2) monitor spacecraft electrostatic charging and the plasma populations responsible for it, for electromagnetic cleanliness and operational purposes.
- [25] arXiv:1911.09367 [pdf, other]
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Title: Star-forming Clumps in Local Luminous Infrared GalaxiesAuthors: K. L. Larson, T. Díaz-Santos, L. Armus, G. C. Privon, S. T. Linden, A. S. Evans, J. Howell, V. Charmandaris, V. U, D. B. Sanders, S. Stierwalt, L. Barcos-Muñoz, J. Rich, A. Medling, D. Cook, A. Oklopĉić, E. J. Murphy, P. BonfiniSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present $HST$ narrow-band near-infrared imaging of Pa$\alpha$ and Pa$\beta$ emission of 48 local Luminous Infrared Galaxies (LIRGs) from the Great Observatories All-Sky LIRG Survey (GOALS). These data allow us to measure the properties of 810 spatially resolved star-forming regions (59 nuclei and 751 extra-nuclear clumps), and directly compare their properties to those found in both local and high-redshift star-forming galaxies. We find that in LIRGs, the star-forming clumps have radii ranging from $\sim90-900$ pc and star formation rates (SFRs) of $\sim1\times10^{-3}$ to 10 M$_\odot$yr$^{-1}$, with median values for extra-nuclear clumps of 170 pc and 0.03 M$_\odot$yr$^{-1}$. The detected star-forming clumps are young, with a median stellar age of $8.7$ Myrs, and a median stellar mass of $5\times10^{5}$ M$_\odot$. The SFRs span the range of those found in normal local star-forming galaxies to those found in high-redshift star-forming galaxies at $\rm{z}=1-3$. The luminosity function of the LIRG clumps has a flatter slope than found in lower-luminosity, star-forming galaxies, indicating a relative excess of luminous star-forming clumps. In order to predict the possible range of star-forming histories and gas fractions, we compare the star-forming clumps to those measured in the MassiveFIRE high-resolution cosmological simulation. The star-forming clumps in MassiveFIRE cover the same range of SFRs and sizes found in the local LIRGs and have total gas fractions that extend from 10 to 90%. If local LIRGs are similar to these simulated galaxies, we expect future observations with ALMA will find a large range of gas fractions, and corresponding star formation efficiencies, among the star-forming clumps in LIRGs.
- [26] arXiv:1911.09368 [pdf, other]
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Title: Planck far-infrared detection of Hyper Suprime-Cam protoclusters at $\bf z\sim4$: hidden AGN and star formation activityAuthors: Mariko Kubo, Jun Toshikawa, Nobunari Kashikawa, Yi-Kuan Chiang, Roderik Overzier, Hisakazu Uchiyama, David L. Clements, David M. Alexander, Yuichi Matsuda, Tadayuki Kodama, Yoshiaki Ono, Tomotsugu Goto, Tai-An Cheng, Kei ItoComments: 26 pages, 12 figures, Accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We perform a stacking analysis of {\it Planck}, {\it AKARI}, Infrared Astronomical Satellite ($IRAS$), Wide-field Infrared Survey Eplorer ($WISE$), and {\it Herschel} images of the largest number of (candidate) protoclusters at $z\sim3.8$ selected from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Stacking the images of the $179$ candidate protoclusters, the combined infrared (IR) emission of the protocluster galaxies in the observed $12-850~\mu$m wavelength range is successfully detected with $>5\sigma$ significance (at $Planck$). This is the first time that the average IR spectral energy distribution (SED) of a protocluster has been constrained at $z\sim4$. The observed IR SEDs of the protoclusters exhibit significant excess emission in the mid-IR compared to that expected from typical star-forming galaxies (SFGs). They are reproduced well using SED models of intense starburst galaxies with warm/hot dust heated by young stars, or by a population of active galactic nuclei (AGN)/SFG composites. For the pure star-forming model, a total IR (from 8 to 1000 $\mu$m) luminosity of $19.3_{-4.2}^{+0.6}\times10^{13}~L_{\odot}$ and a star formation rate (SFR) of $16.3_{-7.8}^{+1.0}\times10^3~M_{\odot}$ yr$^{-1}$ are found whereas for the AGN/SFG composite model, $5.1_{-2.5}^{+2.5}\times10^{13}~L_{\odot}$ and $2.1^{+6.3}_{-1.7}\times10^3~M_{\odot}$ yr$^{-1}$ are found. Uncertainty remaining in the total SFRs; however, the IR luminosities of the most massive protoclusters are likely to continue increasing up to $z\sim4$. Meanwhile, no significant IR flux excess is observed around optically selected QSOs at similar redshifts, which confirms previous results. Our results suggest that the $z\sim4$ protoclusters trace dense, intensely star-forming environments that may also host obscured AGNs missed by the selection in the optical.
- [27] arXiv:1911.09372 [pdf, other]
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Title: Axion-like particles and high energy astrophysicsAuthors: Giorgio GalantiComments: 6 pages, 3 figures, Proceeding of "PHOTON 2019 - International Conference on the Structure and the Interactions of the Photon", June 3-7, 2019, Frascati - Italy, Frascati Physics Series Vol. 69 (2019)Journal-ref: Frascati Physics Series Vol. 69 (2019)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Axion-like particles (ALPs) are light, neutral, pseudo-scalar bosons predicted by several extensions of the Standard Model of particle physics -- such as the String Theory -- and are supposed to interact primarily only with two photons. In the presence of an external magnetic field, photon-ALP oscillations occur and can produce sizable astrophysical effects in the very-high energy (VHE) band ($100 \, {\rm GeV} - 100 \, {\rm TeV}$). Photon-ALP oscillations increase the transparency of the Universe to VHE photons partially preventing the gamma-gamma absorption caused by the Extragalactic Background Light (EBL). Moreover, they have important implications for active galactic nuclei (AGN) by modifying their observed spectra both for flat spectrum radio quasars (FSRQs) and BL Lacs. Many attempts have been made in order to constrain the ALP parameter space by studying irregularities in spectra due to photon-ALP conversion in galaxy clusters and the consequences of ALP emission by stars. Upcoming new VHE photon detectors like CTA, HAWC, GAMMA-400, LHAASO, TAIGA-HiSCORE, HERD and ASTRI will settle the issue.
- [28] arXiv:1911.09387 [pdf, ps, other]
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Title: Unity and Diversity of Yellow Hypergiants FamilyAuthors: V.G. KlochkovaComments: 24 pages, 10 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We summarize the results of long-term spectral monitoring of yellow hypergiants (YHGs) of northern hemisphere with a R$\ge$60000 resolution. The spectra of these F-G stars of extremely high luminosity, compactly located at the top of the Hertzsprung-Russell diagram revealed a variety of spectral features: various types of H$\alpha$ profile, the presence (or absence) of forbidden and permitted emissions, as well as circumstellar components. Variability of spectral details of various nature is studied. Absolute luminosity, circumstellar envelope expansion rate and amplitude of pulsations are determined. The reliability of the YHG status for V1427 Aql is reliably confirmed; manifestations of a significant dynamic instability of the upper layers of the atmosphere of $\rho$ Cas after the 2017 ejection and stratification of its gas envelope are registered; the lack of companion in the system of the V509 Cas hypergiant is proven; a conclusion is made that the V1302 Aql hypergiant is approaching to the low-temperature boundary of the Yellow Void.
- [29] arXiv:1911.09396 [pdf, ps, other]
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Title: HI column density statistics of the cold neutral medium from absorption studiesComments: 6 pages, 4 figuresJournal-ref: Monthly Notices of the Royal Astronomical Society, stz3148, 11 Nov, 2019Subjects: Astrophysics of Galaxies (astro-ph.GA)
Physical properties of the tiny scale structures in the cold neutral medium (CNM) of galaxies is a long-standing puzzle. Only a few lines of sights in our Galaxy have been studies with mixed results on the scale-invariant properties of such structures. Moreover, since these studies measure the variation of neutral hydrogen optical depth, they do not directly constrain the density structures. In this letter, we investigate the possibility of measuring the properties of density and spin temperature structures of the \HI from absorption studies of \HI. Our calculations show that irrespective of the thermal properties of the clouds, the scale structure of the \HI column density can be estimated, whereas, \HI absorption studies alone cannot shed much light on either the amplitude of the density fluctuations and their temperature structures. Detailed methodology and calculations with some fiducial examples are presented.
- [30] arXiv:1911.09407 [pdf, ps, other]
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Title: Redshifted 21-cm emission signal from the halos in Dark AgesComments: 18 pages, 10 figures, 7 tables; accepted for publication in Physics of the Dark UniverseSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The emission in the hyperfine structure 21 cm line of atomic hydrogen arising in the halos with masses $\sim10^6-10^{10}$ M$_\odot$ from the Dark Ages in the models with Warm Dark Matter (WDM) is analysed. The halos are assumed to be formed from Gaussian density peaks of cosmological density perturbations at $10\lesssim z\lesssim50$. Semi-analytical modelling of the formation of individual spherical halos in multi-component models shows that gas in them has the kinetic temperature in the range of $60-800$ K under adiabatic compression of the collapsing halo, and the temperature of each halo depends on the time of virialization. It is shown that inelastic collisions between neutral hydrogen atoms are the dominant excitation mechanism for hyperfine structure levels, which pulls the spin temperature closer to the kinetic temperature. The brightness temperature of individual halos is in the range of 1-10 K, depending on the mass of the halo and its virialization redshift, and increasing as these two increase. The apparent angular radii of such halos are in the range 0.06-1.2 arcseconds, their surface number density decreasing exponentially from a few per arcmin$^2$ for the lowest mass and redshift to nearly zero for higher values. Assuming a 1 MHz observation bandwidth the surface number density of the halo at various redshifts is evaluated as well as beam-averaged differential antenna temperatures and fluxes of hydrogen emission from halos of different masses. The beam-averaged signal strongly depends on the cut-off scale in the mass function of dark ages halos that may be caused by free-streaming of WDM particles. The finding is compared with the upper limits on the amplitude of the power spectrum of the hydrogen 21-cm line fluctuations derived from the recent observation data obtained with MWA and LOFAR.
- [31] arXiv:1911.09413 [pdf, ps, other]
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Title: Properties of carbon stars in the Solar neighbourhood based on Gaia DR2 astrometryComments: Accepted in Astronomy & AstrophysicsSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We find that the combined LF of N- and SC-type stars are consistent with a Gaussian distribution peaking at M_bol~ -5.2 mag. The resulting LF however shows two tails at lower and higher luminosities more extended than those previously found, indicating that AGB carbon stars with Solar metallicity may reach M_bol~-6.0 mag. We find that J-type stars are about half a magnitude fainter on average than N- and SC-type stars, while R-hot stars are half a magnitude brighter than previously found. The Galactic spatial distribution and velocity components of the N-, SC- and J-type stars are very similar, while about 30 % of the R-hot stars in the sample are located at distances larger than ~ 500 pc from the Galactic Plane, and show a significant drift with respect to the local standard of rest. The LF derived for N- and SC-type in the Solar neighbourhood fully agrees with the expected luminosity of stars of 1.5-3 M_o on the AGB. On a theoretical basis, the existence of an extended low luminosity tail would require a contribution of extrinsic low mass carbon stars, while the high luminosity one would imply that stars with mass up to ~5 Mo may become carbon star on the AGB. J-type stars not only differ significantly in their chemical composition with respect to the N- and SC-types but also in their LF, which reinforces the idea that these carbon stars belong to a dvifferent type whose origin is still unknown. The derived luminosities of R-hot stars make these stars unlikely to be in the red-clump as previously claimed. On the other hand, the derived spatial distribution and kinematic properties, together with their metallicity, indicate that most of the N-, SC- and J-type stars belong to the thin disc population, while a significant fraction of R-hot stars show characteristics compatible with the thick disc.
- [32] arXiv:1911.09417 [pdf, other]
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Title: First simulations of axion minicluster halosComments: 8 pages, 6 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We study the gravitational collapse of axion dark matter fluctuations in the post-inflationary scenario, so-called axion miniclusters, with N-body simulations. Largely confirming theoretical expectations, overdensities begin to collapse in the radiation-dominated epoch and form an early distribution of miniclusters with masses up to $10^{-12}\,M_\odot$. After matter-radiation equality, ongoing mergers give rise to a steep power-law distribution of minicluster halo masses. The density profiles of well-resolved halos are NFW-like to good approximation. The fraction of axion DM in these bound structures is $\sim 0.75$ at redshift $z=100$.
- [33] arXiv:1911.09424 [pdf, other]
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Title: The flickering nuclear activity of Fornax AAuthors: F. M. Maccagni, M. Murgia, P. Serra, F. Govoni, K. Morokuma-Matsui, D. Kleiner, S. Buchner, G. I. J. Józsa, P. Kamphuis, S. Makhathini, D. Cs. Molnár, D. A. Prokhorov, A. Ramaila, M. Ramatsoku, K. Thorat, O. SmirnovComments: Accepted for publication in Astronomy & AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present new observations of Fornax A taken at 1 GHz with the MeerKAT telescope and at 6 GHz with the Sardinia Radio Telescope (SRT). The sensitive (noise ~16 micro-Jy beam$^{-1}$), high resolution ( < 10'') MeerKAT images show that the lobes of Fornax A have a double-shell morphology, where dense filaments are embedded in a diffuse and extended cocoon. We study the spectral properties of these components by combining the MeerKAT and SRT observations with archival data between 84 MHz and 217 GHz. For the first time, we show that multiple episodes of nuclear activity must have formed the extended radio lobes. The modelling of the radio spectrum suggests that the last episode of injection of relativistic particles into the lobes started ~ 24 Myr ago and stopped approximately 12 Myr ago. More recently (~ 3 Myr ago), a less powerful and short ( < 1 Myr) phase of nuclear activity generated the central jets. Currently, the core may be in a new active phase. It appears that Fornax A is rapidly flickering. The dense environment in which Fornax A lives has lead to a complex recent merger history for this galaxy, including mergers spanning a range of gas contents and mass ratios, as shown by the analysis of the galaxy's stellar- and cold-gas phases. This complex recent history may be the cause of the rapid, recurrent nuclear activity of Fornax A.
- [34] arXiv:1911.09434 [pdf, other]
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Title: Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS ObservationsAuthors: A. Archer, W. Benbow, R. Bird3, A. Brill, R. Brose, M. Buchovecky, J. L. Christiansen, A. J. Chromey, W. Cui, A. Falcone, Q. Feng, J. P. Finley, L. Fortson, A. Furniss, A. Gent, G. H. Gillanders, C. Giuri, O. Gueta, D. Hanna, T. Hassan, O. Hervet, J. Holder, G. Hughes, T. B. Humensky, P. Kaaret, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, M. J. Lang, G. Maier, P. Moriarty, R. Mukherjee, D. Nieto, M. Nievas-Rosillo, S. O'Brien, R. A. Ong, A. N. Otte, N. Park, A. Petrashyk, K. Pfrang, M. Pohl, R. R. Prado, E. Pueschel, J. Quinn, K. Ragan, P. T. Reynolds, D. Ribeiro, G. T. Richards, E. Roache, I. Sadeh, M. Santander, S. Schlenstedt, G. H. Sembroski, I. Sushch, A. Weinstein, P. Wilcox, A. Wilhelm, D. A. Williams, T. J Williamson, C. J. Hailey, S. Mandel, K. MoriComments: Accepted for publication in The Astrophysical JournalSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
HESS J0632+057 is a gamma-ray binary composed of a compact object orbiting a Be star with a period of about $315$ days. Extensive X-ray and TeV gamma-ray observations have revealed a peculiar light curve containing two peaks, separated by a dip. We present the results of simultaneous observations in hard X-rays with NuSTAR and in TeV gamma-rays with VERITAS, performed in November and December 2017. These observations correspond to the orbital phases $\phi\approx0.22$ and $0.3$, where the fluxes are rising towards the first light-curve peak. A significant variation of the spectral index from 1.77$\pm$0.05 to 1.56$\pm$0.05 is observed in the X-ray data. The multi-wavelength spectral energy distributions (SED) derived from the observations are interpreted in terms of a leptonic model, in which the compact object is assumed to be a pulsar and non-thermal radiation is emitted by high-energy electrons accelerated at the shock formed by the collision between the stellar and pulsar wind. The results of the SED fitting show that our data can be consistently described within this scenario, and allow us to estimate the magnetization of the pulsar wind at the location of the shock formation. The constraints on the pulsar-wind magnetization provided by our results are shown to be consistent with those obtained from other systems.
- [35] arXiv:1911.09439 [pdf, other]
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Title: Measuring $H_0$ from low-$z$ datasetsComments: 4 pages, 1 figureSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Adopting the low-redshift observational datasets, including the Pantheon sample of Type Ia supernovae, baryon acoustic oscillation measurements, and the tomographic Alcock-Paczynski method, we determine the Hubble constant to be $67.95^{+0.78}_{-1.03}$ , $69.81^{+2.22}_{-2.70}$ and $66.75^{+3.42}_{-4.23}$ km s$^{-1}$ Mpc$^{-1}$ at 68\% confidence level in the $\Lambda$CDM, $w$CDM and $w_0w_a$CDM models, respectively. Compared to the Hubble constant given by Riess et al. in 2019, we conclude that the new physics beyond the standard $\Lambda$CDM model is needed if all of these datasets are reliable.
- [36] arXiv:1911.09456 [pdf, other]
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Title: Ammonia in circumstellar environment of V CygSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
The HIFI instrument on board of the Herschel Space Observatory (HSO) has been very successful in detecting molecular lines from circumstellar envelopes around evolved stars, like massive red supergiants, Asymptotic Giant Branch (AGB) and post-AGB stars, as well as planetary nebulae. Among others, ammonia has been found in circumstellar envelopes of C-rich AGB stars in amounts that significantly exceeded theoretical predictions for C-rich stars. Few scenarios have been proposed to resolve this problem: formation of ammonia behind the shock front, photochemical processes in the inner part of the envelope partly transparent to UV background radiation due to the clumpy structure of the gas, and formation of ammonia on dust grains. Careful analysis of observations may help to put constraints on one or another mechanism of ammonia formation. Here, we present results of the non-LTE radiative transfer modeling of ammonia transitions including a crucial process of radiative pumping via v$_2$ = 1 vibrational band (at $\sim$10 $\mu$m) for V Cyg. Only ground-based ammonia transition NH$_{3}$ J = 1$_{0}$ - 0$_{0}$ at 572.5 GHz has been observed by HIFI. Therefore, to determine abundance of ammonia we estimate a photodissociation radius of NH$_{3}$ using chemical model of the envelope consistent with dust grain properties concluded from the spectral energy distribution.
- [37] arXiv:1911.09466 [pdf, ps, other]
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Title: Impact of polarised extragalactic sources on the measurement of CMB B-mode anisotropiesComments: Submitted to A&A, comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
One of the main goals of Cosmology is to search for the imprint of primordial gravitational waves in the CMB polarisation field, to probe inflationary theories. One of the obstacles toward the detection of the primordial signal is to extract the B-mode polarisation from astrophysical contaminations. We present a complete analysis of extragalactic foreground contamination due to polarised emission of radio and dusty star-forming galaxies. We update or use up-to-date models that are validated using the most recent measurements. We predict the flux limit (confusion noise) for the future CMB space or balloon experiments (IDS, PIPER, SPIDER, LiteBIRD, PICO), as well as ground-based experiments (C-BASS, NEXT-BASS, QUIJOTE, AdvACTPOL, BICEP3+Keck, BICEPArray, CLASS, SO, SPT3G, S4). Telescope aperture size (and frequency) is the main characteristic impacting the level of confusion noise. Using the flux limits and assuming constant polarisation fractions for radio and dusty galaxies, we compute the B-mode power spectra of the three extragalactic foregrounds (radio source shot noise, dusty galaxy shot noise and clustering), discuss their relative levels and compare their amplitudes to that of the primordial tensor modes parametrized by the tensor-to-scalar ratio r. At the reionization bump (l=5), contamination by extragalactic foregrounds is negligible. At the recombination peak (l=80), while the contamination is much lower than the targeted sensitivity on r for large-aperture telescopes, it is at comparable level for some of the medium- and small-aperture telescope experiments. For example, the contamination is at the level of the 68 per cent confidence level uncertainty on the primordial r for the LiteBIRD and PICO space experiments. Finally we also provide some useful unit conversion factors and give some predictions for the SPICA B-BOP experiment. Abridged
- [38] arXiv:1911.09555 [pdf, ps, other]
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Title: A Case Study of the May 30th, 2017 Italian FireballAuthors: A. Carbognani, D. Barghini, D. Gardiol, M. di Martino, G. B. Valsecchi, P. Trivero, A. Buzzoni, S. Rasetti, D. Selvestrel, C. Knapic, E. Londero, S. Zorba, C. A. Volpicelli, M. Di Carlo, J. Vaubaillon, C. Marmo, F. Colas, D. Valeri, F. Zanotti, M. Morini, P. Demaria, B. Zanda, S. Bouley, P. Vernazza, J. Gattacceca, J.-L. Rault, L. Maquet, M. BirlanComments: 19 pages, 17 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
On May 30th, 2017 at about 21h 09m 17s UTC a green bright fireball crossed the sky of north-eastern Italy. The fireball path was observed from some all-sky cameras starting from a mean altitude of $81.1 \pm 0.2$ km (Lat. $44.369^{\circ} \pm 0.002^{\circ}$ N; Long. $11.859^{\circ} \pm 0.002^{\circ}$ E) and extinct at $23.3 \pm 0.2$ km (Lat. $45.246^{\circ} \pm 0.002^{\circ}$ N; Long. $12.046^{\circ} \pm 0.002^{\circ}$ E), between the Italian cities of Venice and Padua. In this paper, on the basis of simple physical models, we will compute the atmospheric trajectory, analize the meteoroid atmospheric dynamics, the dark flight phase (with the strewn field) and compute the best heliocentric orbit of the progenitor body. Search for meteorites on the ground has not produced any results so far.
- [39] arXiv:1911.09558 [pdf, other]
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Title: The young stellar content of the giant HII regions M8, G333.6-0.2, and NGC6357 with VLT/KMOSAuthors: M.C. Ramírez-Tannus, J. Poorta, A. Bik, L. Kaper, A. de Koter, J. De Ridder, H. Beuther, W. Brandner, B. Davies, M. Gennaro, D. Guo, T. Henning, H. Linz, T. Naylor, A. Pasquali, O.H. Ramírez-Agudelo, H. SanaComments: Accepted for publication in A&A. The arXiv version includes appendix C, which is an online only figure in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Context: The identification and characterisation of populations of young massive stars in (giant) HII regions provides important constraints on i) the formation process of massive stars and their early feedback on the environment, and ii) the initial conditions for population synthesis models predicting the evolution of ensembles of stars. Aims: We identify and characterise the stellar populations of the following young giant HII regions: M8, G333.6-0.2, and NGC6357. Methods: We acquired H- and K-band spectra of around 200 stars using The K-band KMOS on the ESO Very Large Telescope. The targets for M8 and NGC6357 were selected from the MYStIX project, which combines X-ray observations with near-infrared and mid-infrared data. For G333.6-0.2, the sample selection is based on the near-infrared colours combined with X-ray data. We introduce an automatic spectral classification method in order to obtain temperatures and luminosities for the observed stars. We analyse the stellar populations using their photometric, astrometric, and spectroscopic properties and compared the position of the stars in the Hertzprung-Russell diagram with stellar evolution models to constrain their ages and mass ranges. Results: We confirm the presence of candidate ionising sources in the three regions and report new ones, including the first spectroscopically identified O stars in G333.6-0.2. In M8 and NGC6357, two populations are identified: i) OB main-sequence stars ($M > 5~\rm{M_{\odot}}$) and ii) pre-main sequence stars ($M\approx0.5-5~\rm{M_{\odot}}$). The ages of the clusters are $\sim$1-3~Myr, $< 3$~Myr, and $\sim$0.5-3~Myr for M8, G333.6-0.2, and NGC6357, respectively. We show that MYStIX selected targets have $>$ 90\% probability of being members of the HII region, whereas a selection based on near infrared (NIR) colours leads to a membership probability of only $\sim$70\%.
- [40] arXiv:1911.09567 [pdf, other]
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Title: Linearity and correction of the BF effect in LSST sensorsAuthors: Craig LageComments: 21 pages, 15 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The Brighter-Fatter (hereafter BF) effect in CCD sensors causes increases in the image size of bright objects due to electrostatic repulsion of collected charges. Correcting this effect in the LSST camera is required in order to meet the science goals of the project, especially galaxy shape measurements for weak lensing. The current plan for BF image correction in the LSST is to use the deconvolution method described in Coulton, et.al. [1]. In this work, we study the linearity of the BF effect and effectiveness of the Coulton correction, using both simulation tools and measurements made on prototype LSST CCDs from both CCD vendors. We conclude that the proposed image correction method may be adequate to meet the LSST science goals, although more work is needed on the algorithms used to generate the image correction kernel from sensor measurements.
- [41] arXiv:1911.09568 [pdf, other]
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Title: XMM-Newton Campaign On Ultraluminous X-ray Source NGC 1313 X-1: Wind vs. State VariabilityAuthors: C. Pinto, D. J. Walton, E. Kara, M. L. Parker, R. Soria, P. Kosec, M. J. Middleton, W. N. Alston, A. C. Fabian, M. Guainazzi, T. P. Roberts, F. Fuerst, H. P. Earnshaw, R. Sathyaprakash, D. BarretComments: 19 pages, 16 figures, 4 tables, submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Most ultraluminous X-ray sources (ULXs) are thought to be powered by neutron stars and black holes accreting beyond the Eddington limit. If the compact object is a black hole or a neutron star with a magnetic field $\lesssim10^{12}$ G, the accretion disc is expected to thicken and launch powerful winds driven by radiation pressure. Evidence of such winds has been found in ULXs through the high-resolution spectrometers onboard XMM-Newton, but several unknowns remain, such as the geometry and launching mechanism of these winds. In order to better understand ULX winds and their link to the accretion regime, we have undertaken a major campaign with XMM-Newton to study the ULX NGC 1313 X-1, which is known to exhibit strong emission and absorption features from a mildly-relativistic wind. The new observations show clear changes in the wind with a significantly weakened fast component (0.2c) and the rise of a new wind phase which is cooler and slower (0.06-0.08c). We also detect for the first time variability in the emission lines which indicates an origin within the accretion disc or in the wind. We describe the variability of the wind in the framework of variable super-Eddington accretion rate and discuss a possible geometry for the accretion disc.
- [42] arXiv:1911.09571 [pdf, other]
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Title: Correlations between mass, stellar kinematics and gas metallicity in Eagle galaxiesComments: 5 pages, 4 figures. Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
The metallicity of star forming gas in galaxies from the Eagle simulations increases with stellar mass. Here we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift $z=0$, galaxies with more rotational support have lower metallicities on average when the stellar mass is below $M_\star\approx10^{10}~\rm{M}_\odot$. This trend inverts at higher values of $M_\star$, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anti-correlation between metallicity and star formation rate at a given stellar mass. We present a simple model based on self-regulation of star formation by supernovae that reproduces the trends seen in the simulation, provided that the feedback efficiency is greater in thin, rotationally supported discs and lower if the gas distribution is more spheroidal. Such a dependence of efficiency on gas morphology is expected, because cooling loses of supernova remnants are reduced in explosions that occur at the lower densities found above or below a disc.
- [43] arXiv:1911.09573 [pdf, ps, other]
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Title: First discovery of trans-iron elements in a DAO-type white dwarf (BD$-22{^\circ}3467$)Comments: 34 pages, 19 FiguresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We have identified 484 lines of the trans-iron elements (TIEs) Zn, Ga, Ge, Se, Br, Kr, Sr, Zr, Mo, In, Te, I, Xe, and Ba, for the first time in the ultraviolet spectrum of a DAO-type WD, namely BD$-22{^\circ}3467$, surrounded by the ionized nebula Abell 35. Our TIE abundance determination shows extremely high overabundances of up to five dex -- a similar effect is already known from hot, H-deficient (DO-type) white dwarfs. In contrast to these where a pulse-driven convection zone has enriched the photosphere with TIEs during a final thermal pulse and radiative levitation has established the extreme TIE overabundances, {here the extreme TIE overabundances are exclusively driven by radiative levitation on the initial stellar metallicity. The very low mass ($0.533^{+0.040}_{-0.025}\,M_\odot$) of BD$-22{^\circ}3467$ implies that a third dredge-up with enrichment of s-process elements in the photosphere did not occur in the AGB precursor.
- [44] arXiv:1911.09577 [pdf, other]
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Title: Physical and electrical analysis of LSST sensorsAuthors: Craig LageComments: 29 pages, 21 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Removing systematic effects from astronomical images taken with CCDs requires a detailed understanding of the physics of the imaging process. To aid in this understanding, we have built detailed electrostatic simulations of the LSST CCDs. In order to build an electrostatic model of the LSST CCDs, physical information about the CCDs is required. These details include things such as the physical dimensions of the components of the CCD, dopant profiles, and in some cases, electrical measurements of the CCD. This work documents the results of these physical and electrical measurements on LSST CCDs.
- [45] arXiv:1911.09582 [pdf, ps, other]
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Title: Discovery of a soft X-ray lag in the Ultraluminous X-ray Source NGC 1313 X-1Authors: E. Kara, C. Pinto, D.J. Walton, W.N. Alston, M. Bachetti, D. Barret, M. Brightman, C.R. Canizares, H.P. Earnshaw, A.C. Fabian, F. Furst, P. Kosec, M.J. Middleton, T.P. Roberts, R. Soria, L. Tao, N.A. WebbComments: Re-submitted to MNRAS after minor revisions, 7 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Ultraluminous X-ray Sources (ULXs) provide a unique opportunities to probe the geometry and energetics of super-Eddington accretion. The radiative processes involved in super-Eddington accretion are not well understood, and so studying correlated variability between different energy bands can provide insights into the causal connection between different emitting regions. We present a spectral-timing analysis of NGC 1313 X-1 from a recent XMM-Newton campaign. The spectra can be decomposed into two thermal-like components, the hotter of which may originate from the inner accretion disc, and the cooler from an optically thick outflow. We find correlated variability between hard (2-10 keV) and soft (0.3-2 keV) bands on kilosecond timescales, and find a soft lag of ~150 seconds. The covariance spectrum suggests that emission contributing to the lags is largely associated with the hotter of the two thermal-like components, likely originating from the inner accretion flow. This is only the third ULX to exhibit soft lags. The lags range over three orders of magnitude in amplitude, but all three are ~5 to ~20 percent of the corresponding characteristic variability timescales. If these soft lags can be understood in the context of a unified picture of ULXs, then lag timescales may provide constraints on the density and extent of radiatively-driven outflows.
- [46] arXiv:1911.09596 [pdf, other]
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Title: Massive neutrinos and degeneracies in Lyman-alpha forest simulationsAuthors: Christian Pedersen, Andreu Font-Ribera, Thomas D. Kitching, Patrick McDonald, Simeon Bird, Anže Slosar, Keir K. Rogers, Andrew PontzenComments: 18 pages, 7 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Using a suite of hydrodynamical simulations with cold dark matter, baryons, and neutrinos, we present a detailed study of the effect of massive neutrinos on the 1-D and 3-D flux power spectra of the Lyman-$\alpha$ (Ly$\alpha$) forest. The presence of massive neutrinos in cosmology induces a scale- and time-dependent suppression of structure formation that is strongest on small scales. Measuring this suppression is a key method for inferring neutrino masses from cosmological data, and is one of the main goals of ongoing and future surveys like eBOSS, DES, LSST, Euclid or DESI. The clustering in the Ly$\alpha$ forest traces the quasi-linear power at late times and on small scales. In combination with observations of the cosmic microwave background, the forest therefore provides some of the tightest constraints on the sum of the neutrino masses. However there is a well-known degeneracy between $\Sigma m_{\nu}$ and the amplitude of perturbations in the linear matter power spectrum. We study the corresponding degeneracy in the 1-D flux power spectrum of the Ly$\alpha$ forest, and for the first time also study this degeneracy in the 3-D flux power spectrum. We show that the non-linear effects of massive neutrinos on the Ly$\alpha$ forest, beyond the effect of linear power amplitude suppression, are negligible, and this degeneracy persists in the Ly$\alpha$ forest observables to a high precision. We discuss the implications of this degeneracy for choosing parametrisations of the Ly$\alpha$ forest for cosmological analysis.
- [47] arXiv:1911.09603 [pdf, other]
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Title: Relic neutrino clustering in the Milky WayAuthors: Pablo F. de SalasComments: To appear in TAUP2019 proceedings at Journal of Physics: Conference SeriesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
The Standard Cosmological Model predicts the existence of relic neutrinos, which are indirectly probed through the effective number of relativistic species in the early Universe. In addition, from neutrino flavour oscillations we know that at least two of the neutrino mass states have a non-zero mass. Since the expansion of the Universe has diluted the energy of relic neutrinos, those that are massive are also non relativistic today. This means that they can be trapped in strong gravitational potentials, such as the one of the Milky Way. We review the calculation of the local overdensity of relic neutrinos produced from the gravitational attraction of our Galaxy, Andromeda and the Virgo cluster, commenting on the implications for an experiment aiming at relic neutrino detection, such as the PTOLEMY project.
- [48] arXiv:1911.09612 [pdf, other]
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Title: Shadowing and multiple rings in the protoplanetary disk of HD 139614Authors: G. A. Muro-Arena, M. Benisty, C. Ginski, C. Dominik, S. Facchini, M. Villenave, R. van Boekel, G. Chauvin, A. Garufi, T. Henning, M. Janson, M. Keppler, A. Matter, F. Ménard, T. Stolker, A. Zurlo, P. Blanchard, D. Maurel, O. Moeller-Nilsson, C. Petit, A. Roux, A. Sevin, F. WildiComments: Accepted for publication in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly due to an inclined (sub-)stellar companion embedded in the disk. We study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. We obtained J- and H-band observations in polarized scattered light with VLT/SPHERE that show strong azimuthal asymmetries. In the outer disk, beyond ~30 au, a broad shadow spans a range of ~240{\deg} in position angle, in the East. A bright ring at ~16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at ~34 au and ~50 au. We created a simple 4-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. We find that the shadow on the outer disk covers a range of position angle too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones -- or a continuously warped region -- to cast this broad shadow on the outer disk. A small misalignment of ~4{\deg} between adjacent components can reproduce most of the observed shadow features. Multiple misaligned disk zones, potentially mimicing a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust depleted gap responsible for a dip in the SED.
- [49] arXiv:1911.09614 [pdf, other]
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Title: Baryon-driven growth of solitonic cores in fuzzy dark matter halosComments: 6 pages, 6 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
We present zoom-in simulations of fuzzy dark matter (FDM) halos including baryons and star-formation with sufficient resolution to follow the formation and evolution of central solitons. We find that their properties are determined by the local dark matter velocity dispersion in the combined dark matter-baryon gravitational potential. This motivates a simple prescription to estimate the radial density profiles of FDM cores in the presence of baryons. As cores become more massive and compact if baryons are included, galactic rotation curve measurements are likely harder to reconcile with FDM.
- [50] arXiv:1911.09622 [pdf, ps, other]
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Title: The Unusual Broadband X-ray Spectral Variability of NGC 1313 X-1 seen with $XMM$-$Newton$, $Chandra$ and $NuSTAR$Authors: D. J. Walton, C. Pinto, M. Nowak, M. Bachetti, R. Sathyaprakash, E. Kara, T. P. Roberts, R. Soria, M. Brightman, C. R. Canizares, H. P. Earnshaw, F. Furst, M. Heida, M. J. Middleton, D. Stern, L. Tao, N. Webb, W. N. Alston, D. Barret, A. C. Fabian, F. A. Harrison, P. KosecComments: 17 pages, 7 figures, submitted to MNRAS; comments welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present results from the major coordinated X-ray observing program on the ULX NGC 1313 X-1 performed in 2017, combining $XMM$-$Newton$, $Chandra$ and $NuSTAR$, focusing on the evolution of the broadband ($\sim$0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above $\sim$10-15 keV, qualitatively similar to the ULX Holmberg IX X-1. We model the multi-epoch data with two-component accretion disc models designed to approximate super-Eddington accretion, allowing for the possibility of both a black hole and a neutron star accretor. With regards to the hotter disc component, the data trace out two distinct tracks in the luminosity-temperature plane, with larger emitting radii and lower temperatures seen at higher observed fluxes. Despite this apparent anti-correlation, each of these tracks individually shows a positive luminosity-temperature relation. Both are broadly consistent with $L\propto{T}^{4}$, as expected for blackbody emission with a constant emitting area, and also with $L\propto{T}^{2}$, as may be expected for an advection-dominated disc around a black hole. We consider a variety of different possibilities that may explain this unusual behaviour. Scenarios in which the innermost flow is suddenly blocked from view by outer regions of the super-Eddington disc/wind can explain the luminosity-temperature behaviour, but are difficult to reconcile with the lack of strong variability at higher energies, assuming that this emission arises from the most compact regions. Instead, we may be seeing evidence for further radial stratification of the accretion flow than is included in the simple models considered, with a combination of winds and advection resulting in the suppressed high-energy variability.
- [51] arXiv:1911.09632 [pdf, other]
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Title: Flat low-loss silicon gradient index lens for millimeter and submillimeter wavelengthsAuthors: Fabien Defrance, Cecile Jung-Kubiak, Sofia Rahiminejad, Theodore Macioce, Jack Sayers, Jake Connors, Simon Radford, Goutam Chattopadhyay, Sunil GolwalaComments: J Low Temp Phys (2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
We present the design, simulation, and planned fabrication process of a flat high resistivity silicon gradient index (GRIN) lens for millimeter and submillimeter wavelengths with very low absorption losses. The gradient index is created by subwavelength holes whose size increases with the radius of the lens. The effective refractive index created by the subwavelength holes is constant over a very wide bandwidth, allowing the fabrication of achromatic lenses up to submillimeter wavelengths. The designed GRIN lens was successfully simulated and shows an expected efficiency better than that of a classic silicon plano-concave spherical lens with approximately the same thickness and focal length. Deep reactive ion etching (DRIE) and wafer-bonding of several patterned wafers will be used to realize our first GRIN lens prototype.
- [52] arXiv:1911.09658 [pdf, other]
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Title: 3D MHD Modeling of the Impact of Subsurface Stratification on the Solar DynamoSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Various models of solar subsurface stratification are tested in the global EULAG-MHD solver to simulate diverse regimes of near-surface convective transport. Sub- and superadiabacity are altered at the surface of the model ($ r > 0.95~R_{\odot}$) to either suppress or enhance convective flow speeds in an effort to investigate the impact of the near-surface layer on global dynamics. A major consequence of increasing surface convection rates appears to be a significant alteration of the distribution of angular momentum, especially below the tachocline where the rotational frequency predominantly increases at higher latitudes. These hydrodynamic changes correspond to large shifts in the development of the current helicity in this stable layer ($r<0.72R_{\odot}$), significantly altering its impact on the generation of poloidal and toroidal fields at the tachocline and below, acting as a major contributor towards transitions in the dynamo cycle. The enhanced near-surface flow speed manifests in a global shift of the toroidal field ($B_{\phi}$) in the butterfly diagram - from a North-South symmetric pattern to a staggered anti-symmetric emergence.
- [53] arXiv:1911.09667 [pdf, other]
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Title: First Resolved Scattered-Light Images of Four Debris Disks in Scorpius-Centaurus with the Gemini Planet ImagerAuthors: Justin Hom, Jennifer Patience, Thomas M. Esposito, Gaspard Duchêne, Kadin Worthen, Paul Kalas, Hannah Jang-Condell, Kezman Saboi, Pauline Arriaga, Johan Mazoyer, Schuyler Wolff, Maxwell A. Millar-Blanchaer, Michael P. Fitzgerald, Marshall D. Perrin, Christine H. Chen, Bruce Macintosh, Brenda C. Matthews, Jason J. Wang, James R. Graham, Franck Marchis, S. Mark Ammons, Vanessa P. Bailey, Travis Barman, Joanna Bulger, Jeffrey K. Chilcote, Tara Cotten, Robert J. De Rosa, René Doyon, Katherine B. Follette, Steven Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Patrick Ingraham, Quinn Konopacky, James E. Larkin, Jerome Maire, Mark S. Marley, Christian Marois, Elisabeth Matthews, Stanimir Metchev, Eric L. Nielsen, Rebecca Oppenheimer, David Palmer, Lisa A. Poyneer, Laurent Pueyo, Abhijith Rajan, et al. (14 additional authors not shown)Comments: 20 pages, 9 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
We present the first spatially resolved scattered-light images of four debris disks around members of the Scorpius-Centaurus (Sco-Cen) OB Association with high-contrast imaging and polarimetry using the Gemini Planet Imager (GPI). All four disks are resolved for the first time in polarized light and one disk is also detected in total intensity. The three disks imaged around HD 111161, HD 143675, and HD 145560 are symmetric in both morphology and brightness distribution. The three systems span a range of inclinations and radial extents. The disk imaged around HD 98363 shows indications of asymmetries in morphology and brightness distribution, with some structural similarities to the HD 106906 planet-disk system. Uniquely, HD 98363 has a wide co-moving stellar companion Wray 15-788 with a recently resolved disk with very different morphological properties. HD 98363 A/B is the first binary debris disk system with two spatially resolved disks. All four targets have been observed with ALMA, and their continuum fluxes range from one non-detection to one of the brightest disks in the region. With the new results, a total of 15 A/F-stars in Sco-Cen have resolved scattered light debris disks, and approximately half of these systems exhibit some form of asymmetry. Combining the GPI disk structure results with information from the literature on millimeter fluxes and imaged planets reveals a diversity of disk properties in this young population. Overall, the four newly resolved disks contribute to the census of disk structures measured around A/F-stars at this important stage in the development of planetary systems.
- [54] arXiv:1911.09670 [pdf, ps, other]
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Title: M51 ULX-7: super-orbital periodicity and constraints on the neutron star magnetic fieldComments: 11 pages, 6 figures, accepted for publication in MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
In the current work we explore the applicability of standard theoretical models of accretion to the observed properties of M51 ULX-7. The spin-up rate and observed X-ray luminosity are evidence of a neutron star with a surface magnetic field of $2-7\times10^{13}$ G, rotating near equilibrium. Analysis of the X-ray light-curve of the system (Swift/XRT data) reveals the presence of a $\sim$39 d super-orbital period. We argue that the super-orbital periodicity is due to disc precession, and that material is accreted onto the neutron star at a constant rate throughout it. Moreover, by attributing this modulation to the free precession of the neutron star we estimate a surface magnetic field strength of $3-4\times10^{13}$ G. The agreement of these two independent estimates provide strong constraints on the surface polar magnetic field strength of the neutron star.
- [55] arXiv:1911.09673 [pdf, ps, other]
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Title: Exploring Whether Super-Puffs Can Be Explained as Ringed ExoplanetsComments: 9 pages, 7 figures, submitted for publication in AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
An intriguing, growing class of planets are the "super-puffs," objects with exceptionally large radii for their masses and thus correspondingly low densities ($\lesssim0.3\rm\,g\,cm^{-3}$). Planets with such extended atmospheres are challenging for current evolutionary models, since they should be susceptible to photoevaporation. Here we consider a different explanation, namely that they have large inferred radii because they are ringed. This would naturally explain why super-puffs have thus far only shown featureless transit spectra. We find that this hypothesis cannot explain all of these objects, but can explain certain super-puffs with currently available data. The close proximity of the super-puffs to their parent stars necessitates rings with a rocky rather than icy composition. This limits the radius of the rings, and makes it challenging to explain the large size of Kepler 51b, 51c, 51d, and 79d unless the ring is composed of porous material. Furthermore, the short tidal locking timescales for Kepler 18d, 223d, and 223e mean that these planets may be spinning too slowly, resulting in a small oblateness and rings that are warped by their parent star. Kepler 87c and 177c have the best chance of being explained by rings, but ~10 ppm photometry is required to test this hypothesis. Although less favored by the arguments presented here, the presence of rings around Kepler 18d, 223d, and 223e would be easier to test (~50-150 ppm photometry). We conclude with a note about the recently discovered super-puff HIP 41378f.
- [56] arXiv:1911.09675 [pdf, ps, other]
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Title: HST/COS Spectra of the Wind Lines of VFTS 102 and 285Authors: Katherine Shepard, Douglas R. Gies, Kathryn V. Lester, Luqian Wang, Zhao Guo, Lex Kaper, Alex De Koter, Hugues SanaComments: Accepted for publication in ApJ. 17 pages, 5 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Rapid rotation in massive stars imposes a latitudinal variation in the mass loss from radiatively driven winds that can lead to enhanced mass loss at the poles (with little angular momentum loss) and/or equator (with maximal angular momentum loss). Here we present an examination of the stellar wind lines of the two O-type stars with the fastest known equatorial velocities, VFTS 102 ($V\sin i = 610 \pm 30$ km/s; O9:Vnnne+) and VFTS 285 ($V\sin i = 609 \pm 29$ km/s; O7.5 Vnnn) in the Large Magellanic Cloud. Ultraviolet spectra of both stars were obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. The spectrum of VFTS 285 displays a fast outflow in N V and a much slower wind in Si IV, and we argue that there is a two-wind regime in which mass loss is strong at the poles (fast and tenuous wind) but dominant at the equator (slow and dense winds). These ions and wind lines are not present in the spectrum of the cooler star VFTS 102, but the double-peaked H$\alpha$ emission in its spectrum implies equatorial mass loss into a circumstellar disk. The results suggest that in the fastest rotating O-stars, most mass is lost as an equatorial outflow, promoting angular momentum loss that contributes to a spin down over time.
- [57] arXiv:1911.09677 [pdf, other]
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Title: The EDGE-CALIFA Survey: Using Optical Extinction to Probe the Spatially-Resolved Distribution of Gas in Nearby GalaxiesAuthors: Jorge K. Barrera-Ballesteros, Dyas Utomo, Alberto D. Bolatto, Sebastián F. Sánchez, Stuart N. Vogel, Tony Wong, Rebecca C. Levy, Dario Colombo, Veselina Kalinova, Peter Teuben, Rubén García-Benito, Bernd Husemann, Damián Mast, Leo BlitzComments: 12 pages, 10 figures. Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present an empirical relation between the cold gas surface density ($\Sigma_{\rm gas}$) and the optical extinction (${\rm A_V}$) in a sample of 103 galaxies from the Extragalactic Database for Galaxy Evolution (EDGE) survey. This survey provides CARMA interferometric CO observations for 126 galaxies included in the Calar Alto Legacy Integral Field Area (CALIFA) survey. The matched, spatially resolved nature of these data sets allows us to derive the $\Sigma_{\rm gas}$-${\rm A_V}$ relation on global, radial, and kpc (spaxel) scales. We determine ${\rm A_V}$ from the Balmer decrement (H$\alpha$/H$\beta$). We find that the best fit for this relation is $\Sigma_{\rm gas} ({\rm M_\odot pc^{-2}})\sim~26~\times~ {\rm A_V}({\rm mag})$, and that it does not depend on the spatial scale used for the fit. However, the scatter in the fits increases as we probe smaller spatial scales, reflecting the complex relative spatial distributions of stars, gas, and dust. We investigate the $\Sigma_{\rm gas}$/ ${\rm A_V}$ ratio on radial and spaxel scales as a function of ${\rm EW(H\alpha)}$. We find that at larger values of ${\rm EW(H\alpha)}$ (i.e., actively star-forming regions) this ratio tend to converge to the value expected for dust-star mixed geometries ($\sim$ 30 $\mathrm{M_{\odot} \,pc^{-2}\,mag^{-1}}$). On radial scales, we do not find a significant relation between the $\Sigma_{\rm gas}$/${\rm A_V}$ ratio and the ionized gas metallicity. We contrast our estimates of $\Sigma_{\rm gas}$ using ${\rm A_V}$ with compilations in the literature of the gas fraction on global and radial scales as well as with well known scaling relations such as the radial star-formation law and the $\Sigma_{\rm gas}$-$\Sigma_*$ relation. These tests show that optical extinction is a reliable proxy for estimating $\Sigma_{\rm gas}$ in the absence of direct sub/millimeter observations of the cold gas.
- [58] arXiv:1911.09678 [pdf, other]
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Title: Intermediate-Mass Black HolesComments: Invited review in Annual Reviews of Astronomy & Astrophysics; an edited final version is to published in 2020Subjects: Astrophysics of Galaxies (astro-ph.GA)
We describe ongoing searches for intermediate-mass black holes with M_BH ~ 100-10^5 M_sun. We review a range of search mechanisms, both dynamical and those that rely on accretion signatures. We find that dynamical and accretion signatures alike point to a high fraction of 10^9-10^10 M_sun galaxies hosting black holes with M_BH<10^5 M_sun. In contrast, there are no solid detections of black holes in globular clusters. There are few observational constraints on black holes in any environment with M_BH ~ 100-10^4 M_sun. Considering low-mass galaxies with dynamical black hole masses and constraining limits, we find that the M_BH-sigma_* relation continues unbroken to M_BH~10^5 M_sun, albeit with large scatter. We believe the scatter is at least partially driven by a broad range in black hole mass, since the occupation fraction appears to be relatively high in these galaxies. We fold the observed scaling relations with our empirical limits on occupation fraction and the galaxy mass function to put observational bounds on the black hole mass function in galaxy nuclei. We are pessimistic that local demographic observations of galaxy nuclei alone could constrain seeding mechanisms, although either high-redshift luminosity functions or robust measurements of off-nuclear black holes could begin to discriminate models.
Cross-lists for Fri, 22 Nov 19
- [59] arXiv:1911.07334 (cross-list from nucl-th) [pdf, other]
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Title: Analysis of the Multi-component Relativistic Boltzmann Equation for Electron Scattering in Big Bang NucleosynthesisComments: 7 pages, 1 figures. This paper supersedes arXiv:1810.05976Subjects: Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Big-bang nucleosynthesis (BBN) is a valuable tool to constrain the physics of the early universe and is the only probe of the radiation-dominated epoch. A fundamental assumption in BBN is that the nuclear velocity distributions obey Maxwell-Boltzmann (MB) statistics as they do in stars. In this paper, however, we suggest that there could be a difference between stellar reaction rates and BBN reaction rates, arising due to their fundamentally different environments. Specifically, the BBN epoch is characterized by a dilute baryon plasma for which the velocity distribution of nuclei is mainly determined by the dominant Coulomb elastic scattering with mildly relativistic electrons. One must therefore deduce the momentum distribution for reacting nuclei from the multi-component relativistic Boltzmann equation. However, the full multi-component relativistic Boltzmann equation has only recently been analyzed and its solution has only been worked out in special cases. Here, we construct the relativistic Boltzmann equation in the context of BBN. We also derive a Langevin model and perform relativistic Monte-Carlo simulations which clarify the baryon distribution during BBN. We show by these analyses that, contrary to our previous claim, the imposition of pressure equilibrium leads to a nuclear distribution that remains very close to MB statistics even during the most relativistic environment relevant to BBN. Hence, the predictions of standard BBN remain unchanged.
- [60] arXiv:1911.09169 (cross-list from hep-th) [pdf, ps, other]
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Title: The Swampland and Screened Modified GravityComments: 24 pagesSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We consider the implications of the swampland conjectures on scalar-tensor theories defined in the Einstein frame in which the scalar interaction is screened. We show that chameleon models are not in the swampland provided the coupling to matter is larger than unity and the mass of the scalar field is much larger than the Hubble rate. We apply these conditions to the inverse power law chameleon and the symmetron. We then focus on the dilaton of string theory in the strong coupling limit, as defined in the string frame. We show that solar system tests of gravity imply that viable dilaton models are not in the swampland. In the future of the Universe, if the low energy description with a single scalar is still valid and the coupling to matter remains finite, we find that the scalar field energy density must vanish for models with the chameleon and symmetron mechanisms. Hence in these models dark energy is only a transient phenomenon. This is not the case for the strongly coupled dilaton, which keeps evolving slowly, leading to a quasi de Sitter space-time.
- [61] arXiv:1911.09210 (cross-list from hep-ph) [pdf, other]
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Title: Convolutional Neural Networks for Direct Detection of Dark MatterAuthors: Charanjit K. Khosa (1), Lucy Mars (1), Joel Richards (1), Veronica Sanz (1, 2 and 3) ((1) Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK, (2) Alan Turing Institute, British Library, 96 Euston Road, London NW1 2DB, UK and (3) Instituto de Física Corpuscular (IFIC), Universidad de Valencia-CSIC, E-46980, Valencia, Spain)Comments: 14 figures, 6 tablesSubjects: High Energy Physics - Phenomenology (hep-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
The XENON1T experiment uses a time projection chamber (TPC) with liquid Xenon to search for Weakly Interacting Massive Particles (WIMPs), a proposed Dark Matter particle, via direct detection. As this experiment relies on capturing rare events, the focus is on achieving a high recall of WIMP events. Hence the ability to distinguish between WIMP and the background is extremely important. To accomplish this, we suggest using Convolutional Neural Networks (CNNs); a Machine Learning procedure mainly used in image recognition tasks. To explore this technique we use XENON collaboration open-source software to simulate the TPC graphical output of Dark Matter signals and main backgrounds. A CNN turns out to be a suitable tool for this purpose, as it can identify features in the images that differentiate the two types of events without the need to manipulate or remove data in order to focus on a particular region of the detector. We find that the CNN can distinguish between the dominant background events (ER) and 500 GeV WIMP events with an accuracy of 87.0\% and a recall of 88.2\%.
- [62] arXiv:1911.09282 (cross-list from nucl-th) [pdf, ps, other]
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Title: Fission of super-heavy elements: $^{132}$Sn-plus-the-rest, or $^{208}$Pb-plus-the-rest ?Comments: 4 pages, 4 figuresSubjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
In this work we try to settle down the controversial predictions on the effect of doubly magic nuclei $^{132}$Sn and $^{208}$Pb on the mass distributions of fission fragments of super-heavy nuclei. For this we have calculated the mass distribution of super-heavy nuclei from $^{286}$Cn to $^{306}$122 within the dynamical 4-dimensional Langevin approach. We have found that in "light" super-heavies the influence of $^{208}$Pb on the mass distributions is present but negligible small. In "heavy" super-heavies, Z=120-122, the (quasi)symmetric peaks and strongly asymmetric peaks at fragment mass $A_F$ close to $A_F$=208 are of comparable magnitude.
- [63] arXiv:1911.09384 (cross-list from gr-qc) [pdf, other]
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Title: On the origin of the LIGO "mystery" noise and the high energy particle physics desertAuthors: Niayesh Afshordi (U-Waterloo and Perimeter)Comments: comments are welcome, 3 pages, 1 figureSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
One of the most ubiquitous features of quantum theories is the existence of zero-point fluctuations in their ground states. For massive quantum fields, these fluctuations decouple from infrared observables in ordinary field theories. However, there is no "decoupling theorem" in Quantum Gravity, and we recently showed that the vacuum stress fluctuations of massive quantum fields source a red spectrum of metric fluctuations given by $\sim$ mass$^5$/frequency in Planck units. I show that this signal is consistent with the reported unattributed persistent noise, or "mystery" noise, in the Laser Interferometer Gravitational-Wave Observatory (LIGO), for the Standard Model of Particle Physics. If this interpretation is correct, then it implies that: 1) This will be a fundamental irreducible noise for all gravitational wave interferometers, and 2) There is no fundamental weakly-coupled massive particle heavier than those in the Standard Model.
- [64] arXiv:1911.09469 (cross-list from gr-qc) [pdf, other]
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Title: Generalized covariant prescriptions for averaging cosmological observablesComments: 26 pages, 7 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We present two new covariant and general prescriptions for averaging scalar observables on spatial regions typical of the observed sources and intersecting the past light-cone of a given observer. The geometrical and physical differences between the two procedures are illustrated by computing the averaged energy flux received by distant sources located on (or between) constant redshift surfaces, and by working in the context of a perturbed $\Lambda$CDM geometry. We find significant differences even limiting our model to scalar metric perturbations and stopping our computations to the leading non-trivial perturbative order.
- [65] arXiv:1911.09674 (cross-list from physics.flu-dyn) [pdf, other]
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Title: The dynamics of stratified horizontal shear flows at low Péclet numberComments: 36 pages, 9 figuresSubjects: Fluid Dynamics (physics.flu-dyn); Solar and Stellar Astrophysics (astro-ph.SR)
We consider the dynamics of a vertically stratified, horizontally-forced Kolmogorov flow. Motivated by astrophysical systems where the Prandtl number is often asymptotically small, our focus is the little-studied limit of high Reynolds number but low P\'eclet number (which is defined to be the product of the Reynolds number and the Prandtl number). Through a linear stability analysis, we demonstrate that the stability of two-dimensional modes to infinitesimal perturbations is independent of the stratification, whilst three-dimensional modes are always unstable in the limit of strong stratification and strong thermal diffusion. The subsequent nonlinear evolution and transition to turbulence is studied numerically using direct numerical simulations. For sufficiently large Reynolds numbers, four distinct dynamical regimes naturally emerge, depending upon the strength of the background stratification: the unstratified turbulent regime; the stratified turbulent regime; the intermittent regime and the viscous regime. By considering dominant balances in the governing equations, we are able to derive scaling laws for each regime which explain the numerical data.
Replacements for Fri, 22 Nov 19
- [66] arXiv:1310.7035 (replaced) [pdf, ps, other]
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Title: Dusty supernovae running the thermodynamics of the matter reinserted within young and massive super stellar clustersAuthors: Guillermo Tenorio-Tagle, Sergiy Silich, Sergio Martínez-González, Casiana Muñoz-Tuñón, Jan Palouš, Richard WünschComments: 13 pages, 4 figures. Accepted for publication in The Astrophysical JournalJournal-ref: Tenorio-Tagle et al. 2013 The Astrophysical Journal 778, 159Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [67] arXiv:1903.05267 (replaced) [pdf, other]
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Title: A Unified No-Scale Model of Modulus Fixing, Inflation, Supersymmetry Breaking and Dark EnergyComments: 6 pages, 1 figure, v2: discussion on phase transitions updated, matches the published versionJournal-ref: Phys. Rev. D 100, 025009 (2019)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
- [68] arXiv:1905.05191 (replaced) [pdf, other]
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Title: The Inflaton Portal to a Highly decoupled EeV Dark Matter ParticleComments: 18 pages, 6 figures, new version after publicationJournal-ref: Phys. Rev. D 100, 043507 (2019)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
- [69] arXiv:1905.13520 (replaced) [pdf, other]
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Title: Demonstration of the broadband half-wave plate using the nine-layer sapphire for the CMB polarization experimentAuthors: Kunimoto Komatsu, Tomotake Matsumura, Hiroaki Imada, Hirokazu Ishino, Nobuhiko Katayama, Yuki SakuraiComments: 24 pages, 16 figuresJournal-ref: J. Astron. Telesc. Instrum. Syst. 5(4), 044008 (2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [70] arXiv:1906.09559 (replaced) [pdf, other]
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Title: A Quark-Nova in the wake of a core-collapse Supernova: a unifying model for long duration Gamma-Ray Bursts and Fast Radio BurstsAuthors: Rachid Ouyed, Denis Leahy, Nico Koning (Department of Physics and Astronomy, University of Calgary, Canada)Comments: 91 pages (includes 4 tables and 28 figures). Accepted for publication in RAASubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [71] arXiv:1907.03012 (replaced) [pdf, other]
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Title: The motion of localized sources in general relativity: gravitational self-force from quasilocal conservation lawsAuthors: Marius Oltean, Richard J. Epp, Carlos F. Sopuerta, Alessandro D. A. M. Spallicci, Robert B. MannComments: v1: 41 pages, 12 figures. To be submitted for publication, comments welcome; v2: 42 pages. Comments and references addedSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
- [72] arXiv:1910.01209 (replaced) [pdf]
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Title: Element Abundances of Solar Energetic Particles and the Photosphere, the Corona, and the Solar WindAuthors: Donald V ReamesComments: 16 pages, 9 figures, published in AtomsJournal-ref: Atoms 7(4) 104 (2019)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
- [73] arXiv:1910.04768 (replaced) [pdf, other]
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Title: Revealing the cosmic evolution of boxy/peanut-shaped bulges from HST COSMOS and SDSSComments: Published in MNRAS (20 pages, 17 figures), November 2019Journal-ref: 2019, MNRAS, 490, 4721Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [74] arXiv:1910.06414 (replaced) [pdf, other]
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Title: Exporting Terrestrial Life Out of the Solar System with Gravitational Slingshots of Earthgrazing BodiesComments: 4 pages, 2 figures; submitted for publicationSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [75] arXiv:1910.11875 (replaced) [pdf, other]
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Title: The mass relations between supermassive black holes and their host galaxies at 1<z<2 with HST-WFC3Authors: Xuheng Ding, John Silverman, Tommaso Treu, Andreas Schulze, Malte Schramm, Simon Birrer, Daeseong Park, Knud Jahnke, Vardha N. Bennert, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Matthew A. Malkan, David SandersComments: Accepted for publication in ApJ; 28 pages, 14 figures, 7 tablesSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [76] arXiv:1911.00210 (replaced) [pdf, other]
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Title: Photometric Redshift Estimation with Galaxy Morphology using Self-Organizing MapsSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [77] arXiv:1911.00299 (replaced) [pdf, other]
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Title: The Interaction Of AGN Jets With ObstaclesAuthors: Núria Torres-AlbàComments: Conference proceedings (HEPRO VII). 11 pages, 3 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [78] arXiv:1911.02632 (replaced) [pdf, other]
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Title: Pions in hot dense matter and their astrophysical implicationsSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
- [79] arXiv:1911.05068 (replaced) [pdf, other]
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Title: The Vanishing & Appearing Sources during a Century of Observations project: I. USNO objects missing in modern sky surveys and follow-up observations of a "missing star"Authors: Beatriz Villarroel, Johan Soodla, Sébastien Comerón, Lars Mattsson, Kristiaan Pelckmans, Martín López-Corredoira, Kevin Krisciunas, Eduardo Guerras, Oleg Kochukhov, Josefine Bergstedt, Bart Buelens, Rudolf E. Bär, Rubén Cubo, J. Emilio Enriquez, Alok C. Gupta, Iñigo Imaz, Torgny Karlsson, M. Almudena Prieto, Aleksey A. Shlyapnikov, Rafael S. de Souza, Irina B. Vavilova, Martin J. WardComments: SETI meets time domain astronomy. Accepted into the Astronomical JournalSubjects: Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [80] arXiv:1911.08634 (replaced) [pdf, other]
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Title: High-Resolution Simulations of Catastrophic Disruptions: Resultant Shape DistributionsComments: 16 pages, 8 figures, accepted for publication in Planetary and Space ScienceSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [81] arXiv:1911.09073 (replaced) [pdf, other]
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Title: Hints, neutrino bounds and WDM constraints from SDSS DR14 Lyman-$α$ and Planck full-survey dataAuthors: Nathalie Palanque-Delabrouille, Christophe Yèche, Nils Schöneberg, Julien Lesgourgues, Michael Walther, Solène Chabanier, Eric ArmengaudComments: submitted to JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
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