adsabs/SciX_UAT_keywords huggingface dataset:
A Trend in the Effective Spin Distribution of LIGO Binary Black Holes with Mass

Binary black holes (BBHs) detected by gravitational wave (GW) observations could be broadly divided into two formation channels: those formed through field binary evolution and those assembled dynamically in dense stellar systems. Each of these formation channels, and their subchannels, populate a distinct region in the effective spin-mass ( ${\chi }_{\mathrm{eff}}$ $-M$) plane. Depending on the branching ratio of different channels, an ensemble of BBHs could show a trend in this plane. Here we fit a mass-dependent distribution for ${\chi }_{\mathrm{eff}}$ to the GWTC-1 BBHs from the first and second observing runs of Advanced LIGO and Advanced Virgo. We find a negative correlation between mass and the mean effective spin ( ${\bar{\chi }}_{\mathrm{eff}}$), and positive correlation with its dispersion ( ${\sigma }_{{\chi }_{\mathrm{eff}}}$) at 75% and 80% confidence. This trend is robust against the choice of mass variable, but most pronounced when the mass variable is taken to be the chirp mass of the binary. The result is consistent with significant contributions from both dynamically assembled and field binaries in the GWTC-1 catalog. The upcoming LIGO O3a data release will critically test this interpretation.

Keywords: ligo; laser interferometry; stellar mass black holes; astrophysical black holes
Hα Reverberation Mapping of the Intermediate-mass Active Galactic Nucleus in NGC 4395

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7 and at the Keck I 10 m telescope using the Low-Resolution Imaging Spectrometer with slit masks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure of relative flux calibration impractical. We demonstrate that spatially resolved data from the IFS can be effectively used to correct the slit-mask spectral light curves. While we obtained no reliable lag owing to the lack of a strong variability pattern in the light curves, we constrain the broad-line time lag to be less than 3 hr, consistent with the photometric lag of ~80 minutes reported by Woo et al. By exploiting the high-quality spectra, we measure the second moment of the broad component of the Hα emission line to be 586 ± 19 km s-1, superseding the lower value reported by Woo et al. Combining the revised line dispersion and the photometric time lag, we update the black hole mass to (1.7 ± 0.3) × 104 M⊙.

Keywords: active galactic nuclei
SuperRAENN: A Semisupervised Supernova Photometric Classification Pipeline Trained on Pan-STARRS1 Medium-Deep Survey Supernovae

Automated classification of supernovae (SNe) based on optical photometric light-curve information is essential in the upcoming era of wide-field time domain surveys, such as the Legacy Survey of Space and Time (LSST) conducted by the Rubin Observatory. Photometric classification can enable real-time identification of interesting events for extended multiwavelength follow-up, as well as archival population studies. Here we present the complete sample of 5243 "SN-like" light curves (in gP1rP1iP1zP1) from the Pan-STARRS1 Medium-Deep Survey (PS1-MDS). The PS1-MDS is similar to the planned LSST Wide-Fast-Deep survey in terms of cadence, filters, and depth, making this a useful training set for the community. Using this data set, we train a novel semisupervised machine learning algorithm to photometrically classify 2315 new SN-like light curves with host galaxy spectroscopic redshifts. Our algorithm consists of an RF supervised classification step and a novel unsupervised step in which we introduce a recurrent autoencoder neural network (RAENN). Our final pipeline, dubbed SuperRAENN, has an accuracy of 87% across five SN classes (Type Ia, Ibc, II, IIn, SLSN-I) and macro-averaged purity and completeness of 66% and 69%, respectively. We find the highest accuracy rates for SNe Ia and SLSNe and the lowest for SNe Ibc. Our complete spectroscopically and photometrically classified samples break down into 62.0% Type Ia (1839 objects), 19.8% Type II (553 objects), 4.8% Type IIn (136 objects), 11.7% Type Ibc (291 objects), and 1.6% Type I SLSNe (54 objects).

Keywords: supernovae; astrostatistics; light curve classification
Observational Prospects of Double Neutron Star Mergers and Their Multimessenger Afterglows: LIGO Discovery Power, Event Rates, and Diversity

The double neutron star (DNS) merger event GW170817 signifies the first multimessenger (MM) event with electromagnetic-gravitational (EM-GW) observations. LIGO-Virgo-KAGRA observational runs O4-5 promise to detect similar events and as yet unknown GW signals, which require confirmation in two or more detectors with comparable performance. To this end, we quantify duty cycles of comparable science quality of data in coincident H1L1-observations, further to seek consistent event rates of astrophysical transients in upcoming EM-GW surveys. Quite generally, discovery power scales with exposure time, sensitivity, and critically depends on the percentage of time when detectors operate at high quality. We quantify coincident duty cycles over a time-frequency domain W × B, defined by segments of duration W = 8 s, motivated by a long-duration descending GW-chirp during GRB170817A, and the minimum detector noise over about B = 100-250 Hz. This detector yield factor satisfies 1%-25% in S5-6 and O1-O3ab, significantly different from duty cycles of H1 and L1 individually with commensurable impact on consistency in event rates in EM-GW surveys. Significant gain in discovery power for signals whose frequency varies slowly in time may be derived from improving detector yield factors by deploying time-symmetric data analysis methods. For O4-5, these can yield improvements by factors up to ${ \mathcal O }({10}^{5})$ relative to existing data and methods. Furthermore, the diversity of MM afterglows to DNS mergers may be greatest for systems similar to GW170817 but possibly less so for systems of substantially different mass such as GW190425. We summarize our findings with an outlook on EM-GW surveys during O4-5 and perspectives for next-generation GRB missions like THESEUS.

Keywords: gravitational waves; gravitational wave detectors; neutron stars
Far-infrared Photometric Redshifts: A New Approach to a Highly Uncertain Enterprise

This paper presents a new approach to deriving far-infrared (FIR) photometric redshifts for galaxies based on their reprocessed emission from dust at rest-frame FIR through millimeter wavelengths. FIR photometric redshifts ("FIR-z") have been used over the past decade to derive redshift constraints for highly obscured galaxies that lack photometry at other wavelengths like the optical/near-IR. Most literature FIR-z fits are performed through ${\chi }^{2}$ minimization to a single galaxy's FIR template spectral energy distribution (SED). The use of a single galaxy template, or modest set of templates, can lead to an artificially low uncertainty estimate on FIR-z's because real galaxies display a wide range in intrinsic dust SEDs. I use the observed distribution of galaxy SEDs (for well-constrained samples across $0\lt z\lt 5$ ) to motivate a new FIR through millimeter photometric redshift technique called MMpz. The MMpz algorithm asserts that galaxies are most likely drawn from the empirically observed relationship between rest-frame peak wavelength, ${\lambda }_{\mathrm{peak}}$ , and total IR luminosity, L ${}_{\mathrm{IR}}$ ; the derived photometric redshift accounts for the measurement uncertainties and intrinsic variation in SEDs at the inferred L ${}_{\mathrm{IR}}$ , as well as heating from the cosmic microwave background at $z\gtrsim 5$ . The MMpz algorithm has a precision of ${\sigma }_{{\rm{\Delta }}z/(1+z)}\approx 0.3\mbox{--}0.4$ , similar to single-template fits, while providing a more accurate estimate of the FIR-z uncertainty with reduced chi-squared of order ${ \mathcal O }({\chi }_{\nu }^{2})=1$ , compared to alternative FIR photometric redshift techniques (with ${ \mathcal O }({\chi }_{\nu }^{2})\approx 10\mbox{--}{10}^{3}$ ).

Keywords: astronomical techniques; millimeter astronomy; submillimeter astronomy
Effects of Barnett Magnetic Dipole-Dipole Interaction on Grain Growth and Destruction

Rapidly spinning magnetic grains can acquire large magnetic dipole moments due to the Barnett effect. Here we study the new effect of Barnett magnetic dipole-dipole interaction on grain-grain collisions and grain growth, assuming that grains are spun up by radiative torques. For the ideal situation in which grains have parallel Barnett dipole moments aligned with the ambient magnetic field, we find that the collision rate between grains having embedded iron inclusions can be significantly enhanced due to Barnett magnetic dipole-dipole interaction when grains rotate suprathermally by radiative torques. We discuss the implications of enhanced collision rate for grain growth and destruction in the circumstellar envelope of evolved stars, photodissociation regions, and protostellar environments. Our results first reveal the potential importance of the dust magnetic properties, magnetic fields, and the local radiation field for grain growth and destruction. Detailed numerical simulations of grain dynamics that take into account the variation of Barnett dipoles and grain alignment are required to quantify the exact role of Barnett dipole-dipole interaction in grain evolution.

Keywords: astrophysical dust processes; dust formation; interstellar dust; dust destruction; galaxy environments; dust physics
Classification of BATSE, Swift, and Fermi Gamma-Ray Bursts from Prompt Emission Alone

Although it is generally assumed that there are two dominant classes of gamma-ray bursts (GRBs) with different typical durations, it has been difficult to classify GRBs unambiguously as short or long from summary properties such as duration, spectral hardness, and spectral lag. Recent work used t-distributed stochastic neighborhood embedding (t-SNE), a machine-learning algorithm for dimensionality reduction, to classify all Swift GRBs as short or long. Here, the method is expanded, using two algorithms, t-SNE and UMAP, to produce embeddings that are used to provide a classification for 1911 BATSE bursts, 1321 Swift bursts, and 2294 Fermi bursts for which both spectra and metadata are available. Although the embeddings appear to produce a clear separation of each catalog into short and long bursts, a resampling-based approach is used to show that a small fraction of bursts cannot be robustly classified. Further, three of the 304 bursts observed by both Swift and Fermi have robust but conflicting classifications. A likely interpretation is that in addition to the two predominant classes of GRBs, there are additional, uncommon types of bursts which may require multiwavelength observations in order to separate them from more typical short and long GRBs.

Keywords: gamma-ray bursters; gamma-ray bursts; dimensionality reduction; classification systems
Probing the Circumgalactic Medium with Fast Radio Bursts: Insights from CAMELS

Most diffuse baryons, including the circumgalactic medium (CGM) surrounding galaxies and the intergalactic medium (IGM) in the cosmic web, remain unmeasured and unconstrained. Fast radio bursts (FRBs) offer an unparalleled method to measure the electron dispersion measures (DMs) of ionized baryons. Their distribution can resolve the missing baryon problem and constrain the history of feedback theorized to impart significant energy to the CGM and IGM. We analyze the Cosmology and Astrophysics with Machine Learning Simulations using three suites, IllustrisTNG, SIMBA, and Astrid, each varying six parameters (two cosmological and four astrophysical feedback), for a total of 183 distinct simulation models. We find significantly different predictions between the fiducial models of the suites owing to their different implementations of feedback. SIMBA exhibits the strongest feedback, leading to the smoothest distribution of baryons and reducing the sight-line-to-sight-line variance in DMs between z = 0 and 1. Astrid has the weakest feedback and the largest variance. We calculate FRB CGM measurements as a function of galaxy impact parameter, with SIMBA showing the weakest DMs due to aggressive active galactic nucleus (AGN) feedback and Astrid the strongest. Within each suite, the largest differences are due to varying AGN feedback. IllustrisTNG shows the most sensitivity to supernova feedback, but this is due to the change in the AGN feedback strengths, demonstrating that black holes, not stars, are most capable of redistributing baryons in the IGM and CGM. We compare our statistics directly to recent observations, paving the way for the use of FRBs to constrain the physics of galaxy formation and evolution.

Keywords: circumgalactic medium; radio transient sources; hydrodynamical simulations; stellar feedback
The Timing of Alluvial Fan Formation on Mars

The history of rivers on Mars is an important constraint on Martian climate evolution. The timing of relatively young, alluvial fan-forming rivers is especially important, as Mars's Amazonian atmosphere is thought to have been too thin to consistently support surface liquid water. Previous regional studies suggested that alluvial fans formed primarily between the Early Hesperian and the Early Amazonian. In this study, we describe how a combination of a global impact crater database, a global geologic map, a global alluvial fan database, and statistical models can be used to estimate the timing of alluvial fan formation across Mars. Using our global approach and improved statistical modeling, we find that alluvial fan formation likely persisted into the last ~2.5 Gyr, well into the Amazonian period. However, the data we analyzed were insufficient to place constraints on the duration of alluvial fan formation. Going forward, more crater data will enable tighter constraints on the parameters estimated in our models and thus further inform our understanding of Mars's climate evolution.

Keywords: mars; planetary surfaces; planetary climates
Unobscured Central Broad-line Regions in Type-1.9 AGN SDSS J1241+2602

Strong evidence is reported to support unobscured broad-line regions (BLRs) in Type-1.9 active galactic nucleus (AGN) SDSS J1241+2602 with reliable broad Hα but no broad Hβ. Commonly, the disappearance of broad Hβ can be explained by the AGN unified model, in which heavily obscured BLRs are expected in Type-1.9 AGNs. Here, based on properties of two kinds of BH masses, the virial BH mass and the BH mass obtained through the M BH-σ relation, an independent method is proposed to test whether there are unobscured central BLRs in a Type-1.9 AGN. By the reliable measurement of stellar velocity dispersion of about 110 ± 12 km s -1 through the host galaxy absorption features in SDSS J1241+2602, the BH mass obtained through the M BH-σ relation is consistent with the virial BH mass (3.43 ± 1.25) × 107 M ⊙ determined through properties of the observed broad Hα without considering the effects of obscurations in SDSS J1241+2602. Meanwhile, if considering heavily obscured BLRs in SDSS J1241+2602, the reddening-corrected virial BH mass is tens of times larger than the value expected from M BH-σ, leading SDSS J1241+2602 to be an outlier in the M BH-σ space with a confidence level higher than 5σ. Therefore, unobscured BLRs are preferred in the Type-1.9 AGN SDSS J1241+2602. The results indicate that it is necessary to check whether unobscured central BLRs are common in Type-1.9 AGNs when testing the unified model of AGNs through properties of Type-1.9 AGNs.

Keywords: active galactic nuclei; active galaxies; emission line galaxies; supermassive black holes
Thirteen New M Dwarf + T Dwarf Pairs Identified with WISE/NEOWISE

We present the discovery of 13 new widely separated T dwarf companions to M dwarf primaries, identified using Wide-field Infrared Survey Explorer/NEOWISE data by the CatWISE and Backyard Worlds: Planet 9 projects (hereafter BYW). This sample represents an ∼60% increase in the number of known M + T systems, and allows us to probe the most extreme products of binary/planetary system formation, a discovery space made available by the CatWISE2020 catalog and the BYW effort. Highlights among the sample are WISEP J075108.79-763449.6, a previously known T9 thought to be old due to its spectral energy distribution, which was found by Zhang et al. (2021b) to be part of a common proper motion pair with L34-26 A, a well-studied young M3 V star within 10 pc of the Sun; CWISE J054129.32-745021.5 B and 2MASS J05581644-4501559 B, two T8 dwarfs possibly associated with the very fast-rotating M4 V stars CWISE J054129.32745021.5 A and 2MASS J05581644-4501559 A; and UCAC3 52-1038 B, which is among the widest late-T companions to main-sequence stars, with a projected separation of ∼7100 au. The new benchmarks presented here are prime JWST targets, and can help us place strong constraints on the formation and evolution theory of substellar objects as well as on atmospheric models for these cold exoplanet analogs.

Keywords: visual binary stars; low mass stars; brown dwarfs; t dwarfs; fundamental parameters of stars
VIDEO: Data Release 5

VIDEO is a deep near-infrared survey which targets 12deg2 over the ELAIS-S1 (2 continuous VIRCAM tiles), XMM-LSS, and E-CDFS (3 continuous VIRCAM tiles, each) extra-galactic fields. This research note presents the final data release (DR5) of all tiles, stacks and the deep stacked data in all areas, VIDEO-ES1, VIDEO-XMM and VIDEO-CDFS in Z, Y, J, H and Ks bands.

Keywords: surveys; galaxies; infrared galaxies; high-redshift galaxies
Thermal and Turbulent Properties of the Warm Neutral Medium in the Solar Neighborhood

The transition from the diffuse warm neutral medium (WNM) to the dense cold neutral medium (CNM) is what set the initial conditions to the formation of molecular clouds. The properties of the turbulent cascade in the WNM, essential to describe this radiative condensation process, have remained elusive in part due to the difficulty in mapping out the structure and kinematics of each H I thermal phase. Here we present an analysis of a 21 cm hyper-spectral data cube from the GHIGLS H I survey where the contribution of the WNM is extracted using ROHSA, a Gaussian decomposition tool that includes spatial regularization. The distance and volume of the WNM emission is estimated using 3D dust extinction map information. The thermal and turbulent contributions to the Doppler line width of the WNM were disentangled using two techniques, one based on the statistical properties of the column density and centroid velocity fields, and the other on the relative motions of CNM structures as a probe of turbulent motions. We found that the volume of WNM sampled here (5.2 × 105 pc3), located at the outer edge of the Local Bubble, shows thermal properties in accordance with expected values for heating and cooling processes typical of the solar neighborhood: Pth/kB = (4.4 ± 2.6) × 103 K cm-3, n = 0.74 ± 0.41 cm-3, and Tk = (6.0 ± 1.3) × 103 K. The WNM has the properties of sub/trans-sonic turbulence, with a turbulent Mach number at the largest scale probed here (l = 130 pc) of ${{ \mathcal M }}_{s}=0.87\pm 0.15$ , a density contrast of ${\sigma }_{\rho /{\rho }_{0}}=0.6\pm 0.2$ , and velocity and density power spectra compatible with k-11/3. The low Mach number of the WNM provides dynamical conditions that allow the condensation mode of thermal instability to grow freely and form CNM structures, as predicted by theory.

Keywords: solar neighborhood; warm neutral medium; interstellar atomic gas
SILVERRUSH. XIII. A Catalog of 20,567 Lyα Emitters at z = 2-7 Identified in the Full-depth Data of the Subaru/HSC-SSP and CHORUS Surveys

We present 20,567 Lyα emitters (LAEs) at z = 2.2 - 7.3 that are photometrically identified by the SILVERRUSH program in a large survey area up to 25 deg2 with deep images of five broadband filters (grizy) and seven narrowband filters targeting Lyα lines at z = 2.2, 3.3, 4.9, 5.7, 6.6, 7.0, and 7.3 taken by the Hyper Suprime-Cam Subaru Strategic Program and the Cosmic HydrOgen Reionization Unveiled with Subaru survey. We select secure >5σ sources showing narrowband color excesses via Lyα break screening, taking into account the spatial inhomogeneity of limiting magnitudes. After removing spurious sources by careful masking and visual inspection of coadded and multiepoch images obtained over the 7 yr of the surveys, we construct LAE samples consisting of 6995, 4641, 726, 6124, 2058, 18, and 5 LAEs at z = 2.2, 3.3, 4.9, 5.7, 6.6, 7.0, and 7.3, respectively, although the z = 7.3 candidates are tentative. Our LAE catalogs contain 289 spectroscopically confirmed LAEs at the expected redshifts from previous work. We demonstrate that the number counts of our LAEs are consistent with previous studies with similar LAE selection criteria. The LAE catalogs will be made public on our project webpage with detailed descriptions of the content and ancillary information about the masks and limiting magnitudes.

Keywords: lyman-alpha galaxies; high-redshift galaxies; galaxy evolution; galaxy formation; catalogs
Ancestral Black Holes of Binary Merger GW190521

GW190521 was the most massive black hole merger discovered by LIGO/Virgo so far, with masses in tension with stellar evolution models. A possible explanation of such heavy black holes is that they themselves are the remnants of previous mergers of lighter black holes. Here we estimate the masses of the ancestral black holes of GW190521, assuming it is the end product of previous mergers. We find that the heaviest parental black holes has a mass of ${56}_{-18}^{+20}$ M ⊙ (90% credible level). We find 70% probability that it is in the 50 M ⊙-120 M ⊙ mass gap, indicating that it may also be the end product of a previous merger. We therefore also compute the expected mass distributions of the "grandparent" black holes of GW190521, assuming they existed. Ancestral black hole masses could represent an additional puzzle piece in identifying the origin of LIGO/Virgo/KAGRA's heaviest black holes.

Keywords: gravitational waves
Anisotropy of Halo Main Sequence Turnoff Stars Measured with New MMT Radial Velocities and Gaia Proper Motions

We measure the anisotropy of the Milky Way stellar halo traced by a dense sample of 18 < r < 21 mag F-type main sequence turnoff stars using Gaia eDR3 proper motions and new radial velocity measurements published here.

Keywords: milky way stellar halo; milky way dynamics; f stars; halo stars