Sazuna/UAT_keywords huggingface dataset:
NuSTAR Observations of Abell 2163: Constraints on Non-thermal Emission. Since the first non-thermal reports of inverse Compton (IC) emission from the intracluster medium (ICM) of galaxy clusters at hard X-ray energies, we have yet to unambiguously confirm IC emission in observations with newer facilities. RXTE detected IC emission in one of the hottest known clusters, Abell 2163 (A2163), a massive merging cluster with a giant radio halo—the presumed source of relativistic electrons IC scattering CMB photons to X-ray energies. The cluster's redshift (z ∼ 0.2) allows its thermal and non-thermal radio emission to fit the field of view of the Nuclear Spectroscopic Telescope Array (NuSTAR), permitting a deep observation capable of confirming or ruling out the RXTE report. The IC flux provides constraints on the average magnetic field strength in a cluster. To determine the global diffuse IC emission in A2163, we fit its global NuSTAR spectrum with four models: single- (1T) and two-temperature (2T), 1T+power-law component (T+IC), and multi-temperature+power law (9T+IC). Each represents different characterizations of the thermal ICM emission, with power-law components added to represent IC emission. We find that the 3-30 keV spectrum can be described by purely thermal emission, with a global average temperature of kT = (11.8 ± 0.2) keV. The IC flux is constrained to &lt;4.0 × 10-12 erg s-1 cm-2 using the 1T+IC model and &lt;1.6 × 10-12 erg s-1 cm-2 with the more physical 9T+IC model, both to 90% confidence levels. Combining these limits with 1.4 GHz diffuse radio data from the VLA, we find the average magnetic field strength to be &gt;0.22 μG and &gt;0.35 μG, respectively, providing the strongest constraints on these values in A2163 to date.

Keywords: Galaxy clusters, Abell clusters, Non-thermal radiation sources, X-ray sources
Fundamental Reference AGN Monitoring Experiment (FRAMEx). I. Jumping Out of the Plane with the VLBA. We present the first results from the Fundamental Reference active galactic nucleus (AGN) Monitoring Experiment, an observational campaign dedicated to understanding the physical processes that affect the apparent positions and morphologies of AGNs. In this work, we obtained simultaneous Swift X-ray Telescope and Very Long Baseline Array (VLBA) radio observations for a snapshot campaign of 25 local AGNs that form a volume-complete sample with hard X-ray (14-195 keV) luminosities above 1042 erg s-1, out to a distance of 40 Mpc. Despite achieving an observation depth of ∼20 μJy, we find that 16 of 25 AGNs in our sample are not detected with the VLBA on milliarcsecond (subparsec) scales, and the corresponding core radio luminosity upper limits are systematically below predictions from the Fundamental Plane of black hole activity. Using archival Jansky Very Large Array (VLA) radio measurements, our sample jumps back onto the Fundamental Plane, suggesting that extended radio emission is responsible for the apparent correlation between radio emission, X-ray emission, and black hole mass. We suggest that this discrepancy is likely due to extranuclear radio emission produced via interactions between the AGN and host environment. We compare VLBA observations of AGNs to VLA observations of nearby Galactic black holes, and we find a mass-independent correlation between radio and X-ray luminosities of black holes of ${L}_{6\mathrm{cm}}$ / ${L}_{2-10\mathrm{keV}}$ ∼10-6, in line with predictions for coronal emission, but allowing for the possibility of truly radio-silent AGNs.

Keywords: Radio cores, Active galactic nuclei, Radio astrometry, X-ray active galactic nuclei
Correlated X-Ray and Optical Variability in the O-type Supergiant ζ Puppis. Analysis of the recent long exposure Chandra X-ray observation of the early-type O star ζ Pup shows clear variability with a period previously reported in optical photometric studies. These 813 ks of HETGS observations taken over a roughly one-year time span have two signals of periodic variability: (1) a high-significance period of 1.7820 ± 0.0008 day, and (2) a marginal detection of periodic behavior close to either 5 days or 6 days. A BRITE-Constellation nanosatellite optical photometric monitoring (using near-contemporaneous observations to the Chandra data) confirms a 1.78060 ± 0.00088 day period for this star. The optical period coincides with the new Chandra period within their error ranges, demonstrating a link between these two wave bands and providing a powerful lever for probing the photosphere-wind connection in this star. The phase lag of the X-ray maximum relative to the optical maximum is ∼ φ = 0.45, but consideration of secondary maxima in both data sets indicates possibly two "hot" spots on the star with an X-ray phase lag of φ = 0.1 each. The details of this periodic variation of the X-rays are probed by displaying a phased and trailed X-ray spectrum and by constructing phased light curves for wavelength bands within the HETGS spectral coverage (ranging down to bands encompassing groups of emission lines). We propose that the 1.78 day period is the stellar rotation period and explore how stellar bright spots and associated corotating interaction regions (CIRs) could explain the modulation of this star's optical and X-ray output and their phase difference.

Keywords: Surface variability, Early-type variable stars, Massive stars, Stellar winds, Corotating streams, X-ray stars
X-Ray Redshifts for Obscured AGN: A Case Study in the J1030 Deep Field. We present a procedure to constrain the redshifts of obscured ( ${N}_{H}\gt {10}^{22}\,{\mathrm{cm}}^{-2}$ ) active galactic nuclei (AGN) based on low count statistics X-ray spectra, which can be adopted when photometric and/or spectroscopic redshifts are unavailable or difficult to obtain. We selected a sample of 54 obscured AGN candidates on the basis of their X-ray hardness ratio, ${\rm{HR}}\gt -0.1$ , in the Chandra deep field (∼479 ks, 335 arcmin2) around the z = 6.3 QSO SDSS J1030+0524. The sample has a median value of ≈80 net counts in the 0.5-7 keV energy band. We estimate reliable X-ray redshift solutions taking advantage of the main features in obscured AGN spectra, like the Fe 6.4 keV ${\rm{K}}\alpha $ emission line, the 7.1 keV Fe absorption edge, and the photoelectric absorption cutoff. The significance of such features is investigated through spectral simulations, and the derived X-ray redshift solutions are then compared with photometric redshifts. Both photometric and X-ray redshifts are derived for 33 sources. When multiple solutions are derived by any method, we find that combining the redshift solutions of the two techniques improves the rms by a factor of 2. Using our redshift estimates ( $0.1\lesssim z\lesssim 4$ ), we derived absorbing column densities in the range $\sim {10}^{22}\mbox{--}{10}^{24}\,{\mathrm{cm}}^{-2}$ and absorption-corrected, 2-10 keV rest-frame luminosities between $\sim {10}^{42}$ and 1045 erg s-1, with median values of ${N}_{H}=1.7\times {10}^{23}\,{\mathrm{cm}}^{-2}$ and ${L}_{2-10\mathrm{keV}}=8.3\times {10}^{43}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ , respectively. Our results suggest that the adopted procedure can be applied to current and future X-ray surveys for sources detected only in X-rays or that have uncertain photometric or single-line spectroscopic redshifts.

Keywords: AGN host galaxies, X-ray active galactic nuclei, X-ray surveys, Active galactic nuclei, Spectral energy distribution, Redshift surveys
A Two-zone Photohadronic Interpretation of the EHBL-like Behavior of the 2016 Multi-TeV Flares of 1ES 1959+650. The high-energy-peaked blazar 1ES 1959+650 is a well-known and well-studied nearby blazar that has undergone several episodes of multi-TeV flaring. In 2002 for the first time an orphan TeV flare was observed from this blazar. During a multiwavelength campaign from 2016 April 29 to November 21, MAGIC telescopes observed multi-TeV flarings during the nights of 2016 June 13 and 14 and July 1 when the position of the synchrotron peak was found to be above 1017 Hz. Also observed was that the second peak of the spectral energy distribution shifted toward higher energy and exhibited extreme HBL-like behavior. The photohadronic model, which is very successful at explaining the multi-TeV flaring from many high energy blazars, including 1ES 1959+650, is applied to study the flaring events of 2016. It is observed that the photohadronic model is unable to explain the observed spectra. Here, we use a two-zone photohadronic model to explain the observed spectra. We clearly demonstrate that the low energy regime (zone-1) of the spectra corresponds to the standard flaring events of the high energy blazar and the high energy regime (zone-2) of the spectra is solely due to the extreme nature of the flaring events. Our two-zone photohadronic model explains the multi-TeV flaring events observed by MAGIC telescopes very well.

Keywords: BL Lacertae objects, High energy astrophysics, Blazars, Relativistic jets, Gamma-rays
Confrontation of Observation and Theory: High-frequency QPOs in X-Ray Binaries, Tidal Disruption Events, and Active Galactic Nuclei. We compile observations of high-frequency quasi-periodic oscillations (QPOs) around black holes, both stellar and supermassive, and compare their positions in the parameter space of black hole mass, spin, and oscillation frequency. We find that supermassive black holes occupy a separate region of parameter space than stellar, and further, that QPOs seen around tidal disruption events rather than Seyfert-type active galactic nuclei (AGN) occupy an entirely different space. We then compare these results to the orbital resonance, diskoseismic, warped disk, and disk-jet coupling theoretical models for the origin of high-frequency QPOs. We find that while oscillations around stellar mass black holes are generally consistent with the above models, supermassive black holes are decidedly not. Oscillations seen in tidal disruption events are consistent with oscillations near the frequency of the innermost stable circular orbit, while QPOs in AGN are not accounted for by any of the physical models in consideration. This indicates that despite the scale invariance of accretion processes implied by a decades-wide correlation between QPO frequency and black hole mass, any theory of high-frequency QPOs must relate the frequency to more than just the mass and spin.

Keywords: X-ray binary stars, Black holes, High energy astrophysics, Tidal disruption, Active galactic nuclei, General relativity
From Supernova to Supernova Remnant: Comparison of Thermonuclear Explosion Models. Progress in the three-dimensional modeling of supernovae (SNe) prompts us to revisit the supernova remnant (SNR) phase. We continue our study of the imprint of a thermonuclear explosion on the SNR it produces, which we started with a delayed detonation model of a Chandrasekhar-mass white dwarf. Here we compare two different types of explosion models, each with two variants: two delayed detonation models (N100ddt, N5ddt) and two pure deflagration models (N100def, N5def), where the N number parameterizes the ignition. The output of each SN simulation is used as input to an SNR simulation carried on until 500 yr after the explosion. While all SNR models become more spherical over time and overall display the theoretical structure expected for a young SNR, clear differences are visible among the models, depending on the geometry of the ignition and on the presence or not of detonation fronts. Compared to N100 models, N5 models have a strong dipole component and produce asymmetric remnants. N5def produces a regular-looking, but offset remnant, while N5ddt produces a two-sided remnant. Pure deflagration models exhibit specific traits: a central overdensity, because of the incomplete explosion, and a network of seam lines across the surface, boundaries between burning cells. Signatures from the SN dominate the morphology of the SNR up to 100-300 yr after the explosion, depending on the model, and are still measurable at 500 yr, which may provide a way of testing explosion models.

Keywords: Supernova remnants, Type Ia supernovae, Supernovae
Modeling Kilonova Light Curves: Dependence on Nuclear Inputs. The mergers of binary neutron stars, as well as black hole-neutron star systems, are expected to produce an electromagnetic counterpart that can be analyzed to infer the element synthesis that occurred in these events. We investigate one source of uncertainties pertinent to lanthanide-rich outflows: the nuclear inputs to rapid neutron capture nucleosynthesis calculations. We begin by examining 32 different combinations of nuclear inputs: eight mass models, two types of spontaneous fission rates, and two types of fission daughter product distributions. We find that such nuclear physics uncertainties typically generate at least one order of magnitude uncertainty in key quantities such as the nuclear heating (one and a half orders of magnitude at 1 day post-merger), the bolometric luminosity (one order of magnitude at 5 days post-merger), and the inferred mass of material from the bolometric luminosity (factor of 8 when considering the 8-10 day region). Since particular nuclear processes are critical for determining the electromagnetic signal, we provide tables of key nuclei undergoing β-decay, α-decay, and spontaneous fission important for heating at different times, identifying decays that are common among the many nuclear input combinations.

Keywords: Neutron stars, Explosive nucleosynthesis, Nucleosynthesis, Light curves, R-process, Nuclear astrophysics
The Dispersion Measure and Scattering of Fast Radio Bursts: Contributions from the Intergalactic Medium, Foreground Halos, and Hosts. We investigate the dispersion measure (DM) and scattering of fast radio bursts (FRBs) by the intergalactic medium (IGM), foreground halos, and host halos using cosmological hydrodynamical simulation. We find that the median DM caused by foreground halos is around 30% of that caused by the IGM, but it has a much larger variance. The DM induced by hosts deviates from a log-normal distribution but exhibits an extended distribution in the range of $1\mbox{--}3000\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ with a median value $\sim 100\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ . Then we produce mock FRB sources, assuming a uniform distribution in the range $z\sim 0\mbox{--}0.82$ , to consider the propagation effect of IGM, foreground, and host halos on FRB signals simultaneously. The DM distribution of mock sources agrees well with the observation. The fitted DM-redshift relation of the mock sources can provide a rough estimation of the redshifts of observed events with errors $\delta z\lesssim 0.15$ . The distribution of mock sources in the DM scattering time (τ) space can also match the observation, assuming a Kolmogorov turbulence model where the inner and outer scales are 1000 km to 1 au and 0.2-10 pc, respectively. Finally, we estimate the relative importance of these media for DM and τ in our models. The IGM and host halos are the primary and secondary sources for the extragalactic DM ( ${\mathrm{DM}}_{\mathrm{exg}}$ ). Meanwhile, the contribution from foreground halos increases as ${\mathrm{DM}}_{\mathrm{exg}}$ increases. The host and foreground halos may be the most important media for scattering. Statistically, the latter may dominate the scattering of events with ${\mathrm{DM}}_{\mathrm{exg}}\gtrsim 200\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ .

Keywords: Intergalactic medium, Circumgalactic medium, Interstellar medium, Radio transient sources
Ultrafaint Dwarfs in a Milky Way Context: Introducing the Mint Condition DC Justice League Simulations. We present results from the "Mint" resolution DC Justice League suite of Milky Way-like zoom-in cosmological simulations, which extend our study of nearby galaxies down into the ultrafaint dwarf (UFD) regime for the first time. The mass resolution of these simulations is the highest ever published for cosmological Milky Way zoom-in simulations run to z = 0, with initial star (dark matter) particle masses of 994 (17900) M⊙, and a force resolution of 87 pc. We study the surrounding dwarfs and UFDs, and find that the simulations match the observed dynamical properties of galaxies with -3 &gt; MV &gt; -19, and reproduce the scatter seen in the size-luminosity plane for rh ≳ 200 pc. We predict the vast majority of nearby galaxies will be observable by the Vera Rubin Observatory's coadded Legacy Survey of Space and Time. We additionally show that faint dwarfs with velocity dispersions ≲5 km s-1 result from severe tidal stripping of the host halo. We investigate the quenching of UFDs in a hydrodynamical Milky Way context and find that the majority of UFDs are quenched prior to interactions with the Milky Way, though some of the quenched UFDs retain their gas until infall. Additionally, these simulations yield some unique dwarfs that are the first of their kind to be simulated, e.g., an H I-rich field UFD, a late-forming UFD that has structural properties similar to Crater 2, as well as a compact dwarf satellite that has no dark matter at z = 0.

Keywords: Hydrodynamical simulations, Dwarf galaxies, Galaxy evolution, Galaxy quenching
Void Galaxies Follow a Distinct Evolutionary Path in the Environmental COntext Catalog. We measure the environmental dependence, where environment is defined by the distance to the third nearest neighbor, of multiple galaxy properties inside the Environmental COntext (ECO) catalog. We focus primarily on void galaxies, which we define as the 10% of galaxies having the lowest local density. We compare the properties of void and non-void galaxies: baryonic mass, color, fractional stellar mass growth rate (FSMGR), morphology, and gas-to-stellar-mass ratio (estimated from a combination of H I data and photometric gas fractions calibrated with the REsolved Spectroscopy Of a Local VolumE survey). Our void galaxies typically have lower baryonic masses than galaxies in denser environments, and they display the properties expected of a lower mass population: they have more late types, are bluer, have a higher FSMGR, and are more gas-rich. We control for baryonic mass and investigate the extent to which void galaxies are different at fixed mass. Void galaxies are bluer, more gas-rich, and more star-forming at fixed mass than non-void galaxies, which is a possible signature of galaxy assembly bias. Furthermore, we show that these trends persist even at fixed mass and morphology, and we find that voids host a distinct population of early types that are bluer and more star-forming than the typical red and quenched early types. In addition to these empirical observational results, we also present theoretical results from mock catalogs with built-in galaxy assembly bias. We show that a simple matching of galaxy properties to (sub)halo properties, such as mass and age, can recover the observed environmental trends in ECO galaxies.

Keywords: Extragalactic astronomy, Voids, Galaxy evolution, Galaxy environments
Numerical Relativity Simulations of the Neutron Star Merger GW170817: Long-term Remnant Evolutions, Winds, Remnant Disks, and Nucleosynthesis. We present a systematic numerical relativity study of the dynamical ejecta, winds, and nucleosynthesis in neutron star (NS) merger remnants. Binaries with the chirp mass compatible with GW170817, different mass ratios, and five microphysical equations of state (EOSs) are simulated with an approximate neutrino transport and a subgrid model for magnetohydrodynamic turbulence up to 100 ms postmerger. Spiral density waves propagating from the NS remnant to the disk trigger a wind with mass flux ∼0.1-0.5 M⊙ s-1, which persists for the entire simulation as long as the remnant does not collapse to a black hole. This wind has average electron fraction ≳0.3 and average velocity ∼0.1-0.17 c and thus is a site for the production of weak r-process elements (mass number A &lt; 195). Disks around long-lived remnants have masses ∼0.1-0.2 M⊙, temperatures peaking at ≲10 MeV near the inner edge, and a characteristic double-peak distribution in entropy resulting from shocks propagating through the disk. The dynamical and spiral-wave ejecta computed in our targeted simulations are not compatible with those inferred from AT2017gfo using two-components kilonova models. Rather, they indicate that multicomponent kilonova models including disk winds are necessary to interpret AT2017gfo. The nucleosynthesis in the combined dynamical ejecta and spiral-wave wind in the long-lived mergers of comparable mass robustly accounts for all the r-process peaks, from mass number ∼75 to actinides in terms of solar abundances. Total abundances are weakly dependent on the EOS, while the mass ratio affects the production of first-peak elements.

Keywords: Gravitational wave astronomy, R-process, Gravitational waves, Nucleosynthesis
Can the Helium-detonation Model Explain the Observed Diversity of Type Ia Supernovae?. We study a sample of 16 Type Ia supernovae (SNe Ia) having both spectroscopic and photometric observations within 2-3 days after the first light. The early B - V colors of such a sample tend to show a continuous distribution. For objects with normal ejecta velocity (NV), the C II λ6580 feature is always visible in the early spectra, while it is absent or very weak in the high-velocity (HV) counterpart. Moreover, the velocities of the detached high-velocity features (HVFs) of the Ca II near-IR triplet (CaIR3) above the photosphere are found to be much higher in HV objects than in NV objects, with typical values exceeding 30,000 km s-1 at 2-3 days. We further analyze the relation between the velocity shift of late-time [Fe II] lines (v[Fe II]) and host galaxy mass. We find that all HV objects have redshifted v[Fe II], while NV objects have both blue- and redshifted v[Fe II]. It is interesting to point out that the objects with redshifted v[Fe II] are all located in massive galaxies, implying that HV and a portion of NV objects may have similar progenitor metallicities and explosion mechanisms. We propose that, with a geometric/projected effect, the He-detonation model may account for the similarity in birthplace environment and the differences seen in some SNe Ia, including B - V colors, C II features, CaIR3 HVFs at early times, and v[Fe II] in the nebular phase. Nevertheless, some features predicted by He-detonation simulation, such as the rapidly decreasing light curve, deviate from the observations, and some NV objects with blueshifted nebular v[Fe II] may involve other explosion mechanisms.

Keywords: Observational astronomy, Optical observation, Type Ia supernovae, Helium burning