Sazuna/UAT_keywords huggingface dataset:
Gravitational-wave Detection and Parameter Estimation for Accreting Black-hole Binaries and Their Electromagnetic Counterpart. We study the impact of gas accretion on the orbital evolution of black-hole binaries initially at large separation in the band of the planned Laser Interferometer Space Antenna (LISA). We focus on two sources: (I) stellar-origin black-hole binaries (SOBHBs) that can migrate from the LISA band to the band of ground-based gravitational-wave (GW) observatories within weeks/months; and (II) intermediate-mass black-hole binaries (IMBHBs) in the LISA band only. Because of the large number of observable GW cycles, the phase evolution of these systems needs to be modeled to great accuracy to avoid biasing the estimation of the source parameters. Accretion affects the GW phase at negative (-4) post-Newtonian order, being thus dominant for binaries at large separations. Accretion at the Eddington or at super-Eddington rate will leave a detectable imprint on the dynamics of SOBHBs. For super-Eddington rates and a 10 yr mission, a multiwavelength strategy with LISA and a ground-based interferometer can detect about 10 (a few) SOBHB events for which the accretion rate can be measured at 50% (10%) level. In all cases, the sky position can be identified within much less than 0.4 deg2 uncertainty. Likewise, accretion at ≳100% of the Eddington rate can be measured in IMBHBs up to redshift z ≈ 0.1, and the position of these sources can be identified within less than 0.01 °2 uncertainty. Altogether, a detection of SOBHBs or IMBHBs would allow for targeted searches of electromagnetic counterparts to black-hole mergers in gas-rich environments with future X-ray detectors (such as Athena) and/or radio observatories (such as SKA).

Keywords: Accretion, Gravitational waves, Astrophysical black holes
Dusty Stellar Birth and Death in the Metal-poor Galaxy NGC 6822. The nearby (∼500 kpc) metal-poor ([Fe/H] ≈ -1.2; Z ≈ 30% Z⊙) star-forming galaxy NGC 6822 has a metallicity similar to systems at the epoch of peak star formation. Through identification and study of dusty and dust-producing stars, it is therefore a useful laboratory to shed light on the dust life cycle in the early universe. We present a catalog of sources combining near- and mid-IR photometry from the United Kingdom Infrared Telescope (J, H, and K) and the Spitzer Space Telescope (IRAC 3.6, 4.5, 5.8, and 8.0 μm and MIPS 24 μm). This catalog is employed to identify dusty and evolved stars in NGC 6822 utilizing three color-magnitude diagrams (CMDs). With diagnostic CMDs covering a wavelength range spanning the near- and mid-IR, we develop color cuts using kernel density estimate (KDE) techniques to identify dust-producing evolved stars, including red supergiant (RSG) and thermally pulsing asymptotic giant branch (TP-AGB) star candidates. In total, we report 1292 RSG candidates, 1050 oxygen-rich AGB star candidates, and 560 carbon-rich AGB star candidates with high confidence in NGC 6822. Our analysis of the AGB stars suggests a robust population inhabiting the central stellar bar of the galaxy, with a measured global stellar metallicity of [Fe/H] = -1.286 ± 0.095, consistent with previous studies. In addition, we identify 277 young stellar object (YSO) candidates. The detection of a large number of YSO candidates within a centrally located, compact cluster reveals the existence of an embedded, high-mass star formation region that has eluded previous detailed study. Spitzer I appears to be younger and more active than the other prominent star-forming regions in the galaxy.

Keywords: Dwarf irregular galaxies, Star forming regions, Asymptotic giant branch stars, Young stellar objects, Infrared photometry
ANTARES and IceCube Combined Search for Neutrino Point-like and Extended Sources in the Southern Sky. A search for point-like and extended sources of cosmic neutrinos using data collected by the ANTARES and IceCube neutrino telescopes is presented. The data set consists of all the track-like and shower-like events pointing in the direction of the Southern Sky included in the nine-year ANTARES point-source analysis, combined with the throughgoing track-like events used in the seven-year IceCube point-source search. The advantageous field of view of ANTARES and the large size of IceCube are exploited to improve the sensitivity in the Southern Sky by a factor of ∼2 compared to both individual analyses. In this work, the Southern Sky is scanned for possible excesses of spatial clustering, and the positions of preselected candidate sources are investigated. In addition, special focus is given to the region around the Galactic Center, whereby a dedicated search at the location of SgrA* is performed, and to the location of the supernova remnant RXJ 1713.7-3946. No significant evidence for cosmic neutrino sources is found, and upper limits on the flux from the various searches are presented.

Keywords: Neutrino astronomy
Variability and the Size-Luminosity Relation of the Intermediate-mass AGN in NGC 4395. We present a variability study of the lowest-luminosity Seyfert 1 nucleus of the galaxy NGC 4395 based on photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a ∼5-minute cadence during a period of 10 days and obtained light curves in the ultraviolet (UV), V, J, H, and K/Ks bands, as well as narrowband Hα. The rms variability is ∼0.13 mag in the Swift UVM2 and V filter light curves, decreasing down to ∼0.01 mag in the K filter. After correcting for the continuum contribution to the Hα narrow band, we measured the time lag of the Hα emission line with respect to the V-band continuum as 55-31+27 - 122-67+33 minutes in 2017 and 49-14+15 - 83-14+13 minutes in 2018, depending on assumptions about the continuum variability amplitude in the Hα narrow band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, owing to the large flux uncertainty of UV observations and the limited time baseline. We determined the active galactic nucleus (AGN) monochromatic luminosity at 5100 Å, λ{Lλ}=(5.75± 0.40)× 1039 erg s-1, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex (≥2.5σ) from the previous best-fit relation of Bentz et al.

Keywords: Intermediate-mass black holes, Reverberation mapping, Active galaxies, Galaxy nuclei, Low-luminosity active galactic nuclei, Active galactic nuclei, Seyfert galaxies
When Gas Dynamics Decouples from Galactic Rotation: Characterizing ISM Circulation in Disk Galaxies. In galactic disks, galactic rotation sets the bulk motion of gas, and its energy and momentum can be transferred toward small scales. Additionally, in the interstellar medium, random and noncircular motions arise from stellar feedback, cloud-cloud interactions, and instabilities, among other processes. Our aim is to comprehend to what extent small-scale gas dynamics is decoupled from galactic rotation. We study the relative contributions of galactic rotation and local noncircular motions to the circulation of gas, Γ, a macroscopic measure of local rotation, defined as the line integral of the velocity field around a closed path. We measure the circulation distribution as a function of spatial scale in a set of simulated disk galaxies and model the velocity field as the sum of galactic rotation and a Gaussian random field. The random field is parameterized by a broken power law in Fourier space, with a break at the scale λc. We define the spatial scale λeq at which galactic rotation and noncircular motions contribute equally to Γ. For our simulated galaxies, the gas dynamics at the scale of molecular clouds is usually dominated by noncircular motions, but in the center of galactic disks galactic rotation is still relevant. Our model shows that the transfer of rotation from large scales breaks at the scale λc, and this transition is necessary to reproduce the circulation distribution. We find that λeq, and therefore the structure of the gas velocity field, is set by the local conditions of gravitational stability and stellar feedback.

Keywords: Hydrodynamical simulations, Interstellar dynamics, Hydrodynamics, Posterior distribution, Galaxy dynamics, Galaxy rotation, Astrophysical fluid dynamics, Astronomical simulations, Astrostatistics strategies
Numerical Modeling of Suprathermal Electron Transport in the Solar Wind: Effects of Whistler Turbulence. The solar wind electron velocity distribution function deviates significantly from an equilibrium Maxwellian distribution and is composed of a Maxwellian core, a suprathermal halo, a field-aligned component strahl, and a higher-energy superhalo. Wave-particle interactions associated with whistler wave turbulence are introduced into the kinetic transport equation to describe the interaction between the suprathermal electrons and the whistler waves and to explain the observation that the halo and the strahl relative densities vary in an opposite sense. An efficient numerical method has been developed to solve the Fokker-Planck kinetic transport equation. Application of the numerical method to suprathermal electrons in the solar wind in the presence of whistler waves is presented. Comparison and analysis between the numerical results and observations are made.

Keywords: Solar wind
Separate Silicate and Carbonaceous Solids Formed from Mixed Atomic and Molecular Species Diffusing in Neon Ice. The formation and growth of refractory matter on pre-existing interstellar dust grain surfaces was studied experimentally by annealing neon-ice matrices in which potential precursors of silicate grains (Mg and Fe atoms, SiO and SiO2 molecules) and of solid carbon (Cn molecules, n = 2-10) were initially isolated. Other molecules, mainly O3, CO, CO2, C3O, and H2O, were embedded at the same time in the matrices. The annealing procedure caused the cold dopants to diffuse and interact in the neon ice. Monitoring the procedure in situ with infrared spectroscopy revealed the disappearance of the silicon oxide and carbon molecules at temperatures lower than 13 K, and the rise of the Si-O stretching band of silicates. Ex situ electron microscopy confirmed the formation of silicate grains and showed that their structure was amorphous. It also showed that amorphous carbon matter was formed simultaneously next to the silicate grains, the two materials being chemically separated. The results of the experiments support the hypothesis that grains of complex silicates and of carbonaceous materials are reformed in the cold interstellar medium, as suggested by astronomical observations and evolution models of cosmic dust masses. Moreover, they show that the potential precursors of one material do not combine with those of the other at cryogenic temperatures, providing us with a clue as to the separation of silicates and carbon in interstellar grains.

Keywords: Interstellar dust, Silicate grains, Laboratory astrophysics, Carbonaceous grains, Interstellar dust processes
Lowly Polarized Light from a Highly Magnetized Jet of GRB 190114C. We report multicolor optical imaging and polarimetry observations of the afterglow of the first TeV-detected gamma-ray burst (GRB), GRB 190114C, using the RINGO3 and MASTER II polarimeters. Observations begin 31 s after the onset of the GRB and continue until ∼7000 s postburst. The light curves reveal a chromatic break at ∼400-500 s, with initial temporal decay α = 1.669 ± 0.013 flattening to α ∼ 1 postbreak, which we model as a combination of reverse and forward shock components with magnetization parameter RB ∼ 70. The observed polarization degree decreases from 7.7% ± 1.1% to 2%-4% 52-109 s postburst and remains steady at this level for the subsequent ∼2000 s at a constant position angle. Broadband spectral energy distribution modeling of the afterglow confirms that GRB 190114C is highly obscured (AV,HG = 1.49 ± 0.12 mag; NH HG = (9.0 ± 0.03) × 1022 cm-2). We interpret the measured afterglow polarization as intrinsically low and dominated by dust - in contrast to the P &gt; 10% measured previously for other GRB reverse shocks - with a small contribution from polarized prompt photons in the first minute. We test whether first- and higher-order inverse Compton scattering in a magnetized reverse shock can explain the low optical polarization and subteraelectronvolt emission but conclude that neither is explained in the reverse shock inverse Compton model. Instead, the unexpectedly low intrinsic polarization degree in GRB 190114C can be explained if large-scale jet magnetic fields are distorted on timescales prior to reverse shock emission.

Keywords: Gamma-ray bursts, Jets, Photometric systems, High energy astrophysics, Polarimetry, Shocks, Magnetic fields
Spatial Distribution of Electromagnetic Waves near the Proton Cyclotron Frequency in ICME Sheath Regions Associated with Quasi-perpendicular Shocks: Wind Observations. Electromagnetic waves (EMWs) near the proton cyclotron frequency fcp are transverse left-handed (LH) or right-handed (RH) polarized waves, and are ubiquitous in the solar wind. However, the characteristics of these waves in the sheath regions of interplanetary coronal mass ejections (ICMEs) are poorly understood. Through a comprehensive survey of Wind magnetic field and plasma data using dynamic spectra and repeated filtering analyses, 700 EMW events (7.1% of the analysis time) are identified in the 62 ICME sheath regions associated with quasi-perpendicular shocks involved with a low shock Mach number Mf and low upstream β1. In the ICME sheath regions, outward (inward)-propagating LH (RH) EMWs have relatively higher counts and longer duration than inward (outward)-propagating LH (RH) EMWs in the plasma frame, consistent with previous STEREO observations. The spatial distributions of the magnetic field, plasma, and frequency parameters of EMWs are also presented in both spacecraft and plasma frames, especially the proton (alpha) temperature anisotropy Tp(α)\perp}/Tp(α)\parallel, α abundance Nα/Np, and normalized differential alpha-proton speed Vd/VA. After removing the Doppler shift, 81.1% (59%) of all outward (inward)-propagating LH EMWs have a frequency below (above) 0.5fcp, while 68.3% (64%) of all outward (inward)-propagating RH EMWs have a frequency smaller (greater) than 0.5fcp. Further investigations of local plasma parameters reveal that different excitation mechanisms for EMWs are in different subregions of the ICME sheath regions. These results are helpful in understanding the important role of EMWs in the solar wind-ICME coupling process with different sheath regions.

Keywords: Solar coronal mass ejection shocks, Solar wind, Interplanetary magnetic fields, Space plasmas
The Surprisingly Low Carbon Mass in the Debris Disk around HD 32297. Gas has been detected in a number of debris disks. It is likely secondary, I.e., produced by colliding solids. Here, we report ALMA Band 8 observations of neutral carbon in the CO-rich debris disk around the 15-30 Myr old A-type star HD 32297. We find that C0 is located in a ring at ∼110 au with an FWHM of ∼80 au and has a mass of (3.5 ± 0.2) × 10-3 M⊕. Naively, such a surprisingly small mass can be accumulated from CO photodissociation in a time as short as ∼104 yr. We develop a simple model for gas production and destruction in this system, properly accounting for CO self-shielding and shielding by neutral carbon, and introducing a removal mechanism for carbon gas. We find that the most likely scenario to explain both C0 and CO observations is one where the carbon gas is rapidly removed on a timescale of order a thousand years and the system maintains a very high CO production rate of ∼15 M⊕ Myr-1, much higher than the rate of dust grind-down. We propose a possible scenario to meet these peculiar conditions: the capture of carbon onto dust grains, followed by rapid CO re-formation and rerelease. In steady state, CO would continuously be recycled, producing a CO-rich gas ring that shows no appreciable spreading over time. This picture might be extended to explain other gas-rich debris disks.

Keywords: Atomic spectroscopy, Submillimeter astronomy, Exoplanet formation, Radio interferometry, Debris disks, Circumstellar gas
Gas Density Perturbations in the Cool Cores of CLASH Galaxy Clusters. We present a systematic study of gas density perturbations in cool cores of high-mass galaxy clusters. We select 12 relaxed clusters from the Cluster Lensing And Supernova survey with Hubble (CLASH) sample and analyze their cool-core features observed with the Chandra X-ray Observatory. Here, we focus on the X-ray residual image characteristics after subtracting their global profile of the X-ray surface brightness distribution. We find that all of the galaxy clusters in our sample have, at least, both one positive and one negative excess regions in the X-ray residual image, indicating the presence of gas density perturbations. We identify and characterize the locally perturbed regions using our detection algorithm, and extract X-ray spectra of the intracluster medium (ICM). The ICM temperature in the positive excess region is lower than that in the negative excess region, whereas the ICM in both regions is in pressure equilibrium in a systematic manner. These results indicate that gas sloshing in cool cores takes place in more than 80% of relaxed clusters (95% CL). We confirm this physical picture by analyzing synthetic X-ray observations of a cool-core cluster from a hydrodynamic simulation, finding that our detection algorithm can accurately extract both the positive and negative excess regions and can reproduce the temperature difference between them. Our findings support the picture that the gas density perturbations are induced by gas sloshing, and a large fraction of cool-core clusters have undergone gas sloshing, indicating that gas sloshing may be capable of suppressing runaway cooling of the ICM.

Keywords: Galaxy clusters, Hydrodynamical simulations, Intracluster medium, X-ray astronomy
Atmospheric Circulation on Black Widow Companions. We present a model for atmospheric wind circulation in binary millisecond pulsar (MSP) companions, showing how the optical light curve (LC) and radial velocities are sensitive to the wind flow, causing LC orbital phase shifts and asymmetries, as observed for several "spider" MSPs. Velocity widths of spectral lines offer additional opportunities for measuring surface wind speed. As examples, we fit optical data for the black widow pulsar J1959+2048 and the redback pulsar J2215+5135; the wind heating models (WH) are statistically strongly preferred over direct heating (DH) for both objects, although the latter is even better fit with a heated spot. In general, WH effects tend to increase the inferred orbital inclination I and decrease the inferred companion center-of-mass radial velocity amplitude Kc; both effects decrease the inferred neutron star mass. Even with such a decrease, we find large masses for the two neutron stars: 2.18 ± 0.09 M☉ and 2.28-0.09+0.10 M☉, respectively (for the modest surface speeds fit from the bulk heat flow; supersonic photospheric winds can slightly change these values). These are among the highest masses known, and our improved modeling increases confidence that the results are important for understanding the dense matter equation of state.

Keywords: Pulsars
X-Ray Scaling Relations for a Representative Sample of Planck-selected Clusters Observed with XMM-Newton. We report the scaling relations derived by fitting the X-ray parameters determined from analyzing the XMM-Newton observations of 120 galaxy clusters in the Planck Early Sunyaev-Zel'dovich (SZ) sample spanning the redshift range of 0.059 &lt; z &lt; 0.546. We find that the slopes of all the investigated scaling relations significantly deviate from the self-similar predictions, if self-similar redshift evolution is assumed. When the redshift evolution is left free to vary, the derived slopes are more in agreement with the self-similar predictions. Relaxed clusters have on average ∼30% higher X-ray luminosity than disturbed clusters at a given mass, a difference that, depending on the relative fraction of relaxed and disturbed clusters in the samples (e.g., SZ vs. X-ray selected), has a strong impact on the normalization obtained in different studies. Using the core-excised cluster luminosities reduces the scatter and brings into better agreement the L-Mtot and L-T relations determined for different samples. Mtot-T, Mtot-YX, and Mtot-Mgas relations show little dependence on the dynamical state of the clusters, but the normalizations of these relations may depend on the mass range investigated. Although most of the clusters investigated in this work reside at relatively low redshift, the fits prefer values of γ, the parameter accounting for the redshift evolution, different from the self-similar predictions. This suggests an evolution (&lt;2σ level, with the exception of the Mtot-T relation) of the scaling relations. For the first time, we find significant evolution (&gt;3σ) of the Mtot-T relation, pointing to an increase of the kinetic-to-thermal energy ratio with redshift. This is consistent with a scenario in which higher-redshift clusters are on average more disturbed than their lower-redshift counterparts.

Keywords: Galaxy clusters, Observational cosmology, Intracluster medium, X-ray astronomy
Multiple Measurements of Quasars Acting as Standard Probes: Exploring the Cosmic Distance Duality Relation at Higher Redshift. General relativity reproduces main current cosmological observations, assuming the validity of the cosmic distance duality relation (CDDR) at all scales and epochs. However, CDDR is poorly tested in the redshift interval between the farthest observed Type Ia supernovae and that of the cosmic microwave background. We present a new idea of testing the validity of CDDR, through the multiple measurements of high-redshift quasars. Luminosity distances are derived from the relation between the UV and X-ray luminosities of quasars, while angular diameter distances are obtained from the compact structure in radio quasars. This will create a valuable opportunity where two different cosmological distances from the same kind of objects at high redshifts are compared. Our constraints are more stringent than other currently available results based on different observational data and show no evidence for the deviation from CDDR at z ∼ 3. Such an accurate model-independent test of fundamental cosmological principles can become a milestone in precision cosmology.

Keywords: Radio loud quasars, X-ray quasars, Quasars, Cosmological parameters
Three Dusty Star-forming Galaxies at z ∼ 1.5: Mergers and Disks on the Main Sequence. The main sequence of galaxies, a correlation between the star formation rates (SFRs) and stellar masses of galaxies, has been observed out to z ∼ 4. Galaxies within the scatter of the correlation are typically interpreted to be secularly evolving while galaxies with SFRs elevated above the main sequence are interpreted to be undergoing interactions or to be Toomre-unstable disks with starbursting clumps. In this paper, we investigate the recent merger histories of three dusty star-forming galaxies, identified by their bright submillimeter emission at z ∼ 1.5. We analyze rest-frame optical and UV imaging, rest-frame optical emission line kinematics using slit spectra obtained with the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on Keck I, and calculate Gini and M20 statistics for each galaxy and conclude two are merger driven while the third is an isolated disk galaxy. The disk galaxy lies ∼4× above the main sequence, one merger lies within the scatter of the main sequence, and one merger lies ∼4× below the main sequence. This hints that the location of a galaxy with respect to the main sequence may not be a useful discriminator of the recent star formation history of high-M\star galaxies at z ∼ 1.

Keywords: Galaxy evolution, Galaxy kinematics, High-redshift galaxies