Sazuna/UAT_keywords huggingface dataset:
Evolution of Interplanetary Coronal Mass Ejection Complexity: A Numerical Study through a Swarm of Simulated Spacecraft. In-situ measurements carried out by spacecraft in radial alignment are critical to advance our knowledge on the evolutionary behavior of coronal mass ejections (CMEs) and their magnetic structures during propagation through interplanetary space. Yet, the scarcity of radially aligned CME crossings restricts investigations on the evolution of CME magnetic structures to a few case studies, preventing a comprehensive understanding of CME complexity changes during propagation. In this Letter, we perform numerical simulations of CMEs interacting with different solar wind streams using the linear force-free spheromak CME model incorporated into the EUropean Heliospheric FORecasting Information Asset model. The novelty of our approach lies in the investigation of the evolution of CME complexity using a swarm of radially aligned, simulated spacecraft. Our scope is to determine under which conditions, and to what extent, CMEs exhibit variations of their magnetic structure and complexity during propagation, as measured by spacecraft that are radially aligned. Results indicate that the interaction with large-scale solar wind structures, and particularly with stream interaction regions, doubles the probability to detect an increase of the CME magnetic complexity between two spacecraft in radial alignment, compared to cases without such interactions. This work represents the first attempt to quantify the probability of detecting complexity changes in CME magnetic structures by spacecraft in radial alignment using numerical simulations, and it provides support to the interpretation of multi-point CME observations involving past, current (such as Parker Solar Probe and Solar Orbiter), and future missions.

Keywords: Corotating streams, Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections
Find the Gap: Black Hole Population Analysis with an Astrophysically Motivated Mass Function. We introduce a novel black hole mass function that realistically models the physics of pair-instability supernovae with a minimal number of parameters. Applying this to all events in the LIGO-Virgo Gravitational-Wave Transient Catalog 2 (GWTC-2), we detect a peak at ${M}_{\mathrm{BHMG}}={46}_{-6}^{+17}\,{M}_{\odot }$. Repeating the analysis without the black holes from the event GW190521, we find this feature at MBHMG = 54 ± 6 M⊙. These results establish the edge of the anticipated "black hole mass gap" at a value compatible with the expectation from standard stellar structure theory. The mass gap manifests itself as a discontinuity in the mass function and is populated by a distinct, less-abundant population of higher-mass black holes. We find that the primary black hole population scales with power-law index -1.95 ± 0.51 (-1.97 ± 0.44) with (without) GW190521, consistent with models of star formation. Using Bayesian techniques, we establish that our mass function fits a new catalog of black hole masses approximately as well as pre-existing phenomenological mass functions. We also remark on the implications of these results for constraining or discovering new phenomena in nuclear and particle physics.

Keywords: Population III stars, Black holes, Astrophysical black holes, Stellar populations, Gravitational wave astronomy, Nuclear astrophysics, Helium burning, Gravitational waves, Particle astrophysics, Stellar evolution
Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Gravitational-wave Bursts and Electromagnetic Counterparts from Merging Stellar Black Hole Binaries. The recent advanced LIGO/Virgo detections of gravitational waves (GWs) from stellar binary black hole (BBH) mergers, in particular GW190521, which is potentially associated with a quasar, have stimulated renewed interest in active galactic nuclei as factories of merging BBHs. Compact objects evolving from massive stars are unavoidably enshrouded by a massive envelope to form accretion-modified stars (AMSs) in the dense gaseous environment of a supermassive black hole (SMBH) accretion disk. We show that most AMSs form binaries due to gravitational interaction with each other during radial migration in the SMBH disk, forming BBHs inside the AMS. When a BBH is born, its orbit is initially governed by the tidal torque of the SMBH. Bondi accretion onto a BBH at a hyper-Eddington rate naturally develops and then controls the evolution of its orbits. We find that Bondi accretion leads to efficient removal of the orbital angular momentum of the binary, whose final merger produces a GW burst. Meanwhile, the Blandford-Znajek mechanism pumps the spin energy of the merged BH to produce an electromagnetic counterpart (EMC). Moreover, hyper-Eddington accretion onto the BBH develops powerful outflows and triggers a Bondi explosion, which manifests itself as an EMC of the GW burst, depending on the viscosity of the accretion flow. Thermal emission from the Bondi sphere appears as one of the EMCs. The BBHs radiate GWs with frequencies of ~102 Hz, which are accessible to LIGO.

Keywords: Supermassive black holes, Active galactic nuclei
Unveiling the Population of Wandering Black Holes via Electromagnetic Signatures. While most galaxies appear to host a central supermassive black hole (SMBH), they are expected to also contain a substantial population of off-center "wandering" SMBHs naturally produced by the hierarchical merger-driven process of galaxy assembly. This population has been recently characterized in an analysis of the ROMULUS cosmological simulations, which correct for the dynamical forces on SMBHs without artificially pinning them to halo centers. Here we predict an array of electromagnetic signatures for these wanderers. The predicted wandering population of SMBHs from ROMULUS broadly reproduces the observed spatial offsets of a recent sample of hyperluminous X-ray sources. We predict that the sources with the most extreme offsets are likely to arise from SMBHs within satellite galaxies. These simulations also predict a significant population of secondary active galactic nuclei (AGNs) with luminosities at least 10% that of the central AGN. The majority of galaxies at z = 4 that host a central AGN with bolometric luminosity Lbol &gt; 1042 erg s-1 are predicted to host a companion off-center AGN of comparable brightness. We demonstrate that stacked X-ray observations of similar mass galaxies may reveal a halo of collective emission attributable to these wanderers. Finally, because wanderers dominate the population of SMBHs with masses of ≲107 M⊙ in ROMULUS, they may dominate tidal disruption event (TDE) rates at these masses if they retain a stellar component (e.g., a nuclear star cluster). This could warrant an order of magnitude correction to current theoretically estimated TDE rates at low SMBH masses.

Keywords: AGN host galaxies, Supermassive black holes, Active galactic nuclei, Hydrodynamical simulations
Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations. We compare the star-forming properties of satellites around Milky Way (MW) analogs from the Stage II release of the Satellites Around Galactic Analogs Survey (SAGA-II) to those from the APOSTLE and Auriga cosmological zoom-in simulation suites. We use archival GALEX UV imaging as a star formation indicator for the SAGA-II sample and derive star formation rates (SFRs) to compare with those from APOSTLE and Auriga. We compare our detection rates from the NUV and FUV bands to the SAGA-II Hα detections and find that they are broadly consistent with over 85% of observed satellites detected in all three tracers. We apply the same spatial selection criteria used around SAGA-II hosts to select satellites around the MW-like hosts in APOSTLE and Auriga. We find very good overall agreement in the derived SFRs for the star-forming satellites as well as the number of star-forming satellites per host in observed and simulated samples. However, the number and fraction of quenched satellites in the SAGA-II sample are significantly lower than those in APOSTLE and Auriga below a stellar mass of M* ~ 108 M⊙, even when the SAGA-II incompleteness and interloper corrections are included. This discrepancy is robust with respect to the resolution of the simulations and persists when alternative star formation tracers are employed. We posit that this disagreement is not readily explained by vagaries in the observed or simulated samples considered here, suggesting a genuine discrepancy that may inform the physics of satellite populations around MW analogs.

Keywords: Quenched galaxies, Dwarf galaxies, Star formation, Galaxy evolution, Galaxy quenching
AGB Interlopers in YSO Catalogs Hunted out by NEOWISE. Asymptotic giant branch stars (AGBs) and young stellar objects (YSOs) often share the same domains in infrared (IR) color-magnitude or color-color diagrams leading to potential misclassification. We extracted a list of AGB interlopers from the published YSO catalogs using the periodogram analysis on the Near-Earth Object Wide Infrared Survey Explorer (NEOWISE) time series data. YSO IR variability is typically stochastic and linked to episodic mass accretion. Furthermore, most variable YSOs are at an early evolutionary stage, with significant surrounding envelope and/or disk material. In contrast, AGBs are often identified by a well-defined sinusoidal variability with periods of a few hundreds days. From our periodogram analysis of all known low-mass YSOs in the Gould Belt, we find 85 AGB candidates, out of which 62 were previously classified as late-stage Class III YSOs. Most of these new AGB candidates have similar IR colors to O-rich AGBs. We observed 73 of these AGB candidates in the H2O, CH3OH, and SiO maser lines to further reveal their nature. The SiO maser emission was detected in 10 sources, confirming them as AGBs because low-mass YSOs, especially Class III YSOs, do not show such maser emission. The H2O and CH3OH maser lines were detected in none of our targets.

Keywords: Asymptotic giant branch stars
Turbulent Acceleration of Interstellar Pickup Ions at the Heliospheric Termination Shock Forms the Global ENA Spectrum. The heliospheric energetic neutral atom spectrum observed by the Interstellar Boundary Explorer (IBEX) reveals that the heliosheath proton distribution is consistent with a power law. The origin of the spectrum is likely from interstellar pickup ions (PUIs) accelerated at the heliospheric termination shock (HTS). We present an explanation of the proton spectrum origin using a test particle simulation of PUIs accelerated at the HTS. PUIs experience preferential heating by the motional electric field in the shock foot, but do not develop a power-law tail without the presence of turbulence at wavenumbers (k) close to the PUI gyroradius scale (Rg). Voyager 2 observations of the magnetic field downstream of the HTS indicate a moderate amount of turbulence at kRg ≅ 1, ${\left(\delta B/{B}_{0}\right)}^{2}\cong 0.01$, which we find to be sufficient for producing a downstream suprathermal PUI tail but not at intensities observed by IBEX. Within the shock ramp, however, Voyager observed the turbulence power at much smaller scales to be nearly 100 times stronger, suggesting the possibility of strong turbulence at the PUI gyroradius scale. We show that a proton distribution can develop a power law downstream of the HTS consistent with IBEX observations if ${\left(\delta B/{B}_{0}\right)}^{2}\gtrsim 0.1$ at kRg ≅ 1 in the shock foot. Shock drift acceleration of PUIs by the motional electric field is aided by interactions with turbulence upstream of the shock overshoot. Steepening of the IBEX proton spectrum in directions farther from the heliospheric nose suggests the HTS compression ratio and/or turbulence power weakens near the heliotail.

Keywords: Space plasmas, Interplanetary turbulence, Termination shock, Solar wind, Pickup ions, Interplanetary particle acceleration, Heliosheath
Observation of Photons above 300 TeV Associated with a High-energy Neutrino from the Cygnus Region. Galactic sites of acceleration of cosmic rays to energies of order 1015 eV and higher, dubbed PeVatrons, reveal themselves by recently discovered gamma radiation of energies above 100 TeV. However, joint gamma-ray and neutrino production, which marks unambiguously cosmic-ray interactions with ambient matter and radiation, was not observed until now. In 2020 November, the IceCube neutrino observatory reported an ~150 TeV neutrino event from the direction of one of the most promising Galactic PeVatrons, the Cygnus Cocoon. Here we report on the observation of a 3.1σ (post-trial) excess of atmospheric air showers from the same direction, observed by the Carpet-2 experiment and consistent with a few months flare in photons above 300 TeV, in temporal coincidence with the neutrino event. The fluence of the gamma-ray flare is of the same order as that expected from the neutrino observation, assuming the standard mechanism of neutrino production. This is the first evidence for the joint production of high-energy neutrinos and gamma-rays in a Galactic source.

Keywords: Neutrino astronomy, Gamma-rays
Quenching, Mergers, and Age Profiles for z = 2 Galaxies in IllustrisTNG. Using the IllustrisTNG cosmological galaxy formation simulations, we analyze the physical properties of young quiescent galaxies at z = 2 with stellar masses above 1010.5 M⊙. This key population provides an unaltered probe into the evolution of galaxies from star-forming to quiescent, and has been recently targeted by several observational studies. Young quiescent galaxies in the simulations do not appear unusually compact, in tension with observations, but they show unique age profiles that are qualitatively consistent with the observed color gradients. In particular, more than half of the simulated young quiescent galaxies show positive age gradients due to recent intense central starbursts, which are triggered by significant mergers. Yet, there is a sizable population of recently quenched galaxies without significant mergers and with flat age profiles. Our results suggest that mergers play a fundamental role in structural transformation, but are not the only available pathway to quench a z = 2 galaxy.

Keywords: Galaxy quenching, Galaxy structure, Post-starburst galaxies, Astronomical simulations
Void Galaxy Distribution: A Challenge for ΛCDM. We extract void catalogs from the Sloan Digital Sky Survey Data Release 16 (SDSS DR16) survey and also from the Millennium simulation. We focus our comparison on distribution of galaxies brighter than Mr &lt; -18 inside voids and study the mean separation of void galaxies, distance from the void center, and the radial density profile. We find that mean separation of void galaxies depends on void size, as bigger voids have lower mean separation in both samples. However, void galaxies in the observation sample seem to have generally larger mean-distance than simulated ones at any given void size. In addition, observed void galaxies tend to reside closer to the void center than those in the simulation. This discrepancy is also shown in the density profile of voids. Regardless of the void size, the central densities of real void profiles are higher than the ones in the predicted simulated catalog.

Keywords: Voids
Long-term Statistics of Pulsar Glitches Due to History-dependent Avalanches. Stress accumulation-relaxation meta-models of pulsar glitches make precise, microphysics-agnostic predictions of long-term glitch statistics, which can be falsified by existing and future timing data. Previous meta-models assume that glitches are triggered by an avalanche process, e.g., involving superfluid vortices, and that the probability density function (PDF) of the avalanche sizes is history independent and specified exogenously. Here, a recipe is proposed to generate the avalanche sizes endogenously in a history-dependent manner, by tracking the thresholds of occupied vortex pinning sites as a function of time. Vortices unpin spasmodically from sites with thresholds below a global, time-dependent stress and repin at sites with thresholds above the global stress, imbuing the system with long-term memory. The meta-model predicts PDFs, auto-, and cross-correlations for glitch sizes and waiting times, which are provisionally inconsistent with current observations, unlike some previous meta-models (e.g., state-dependent Poisson process), whose predictions are consistent. The theoretical implications are intriguing, albeit uncertain, because history-dependent avalanches embody faithfully the popular, idealized understanding in the literature of how vortex unpinning operates as a driven, stochastic process. The meta-model predicts aftershocks, which occur with larger than average sizes and longer than average waiting times after the largest, system-resetting glitches. This prediction will be tested, once more data are generated by the next generation of pulsar timing campaigns.

Keywords: Neutron stars, Stellar rotation, Astrostatistics, Pulsars
Do the Periodic Activities of Repeating Fast Radio Bursts Represent the Spins of Neutron Stars?. Fast radio bursts (FRBs) are mysterious radio transients with millisecond durations. Recently, ~16 days of periodic activity and ~159 days of possible periodicity were detected to arise from FRB 180916.J0158+65 and FRB 121102, respectively, and the spin period of a slow-rotation magnetar was further considered to be one of the possible explanations of the periodic activities of repeating FRBs. For isolated neutron stars, the spin evolution suggests that it has difficulty reaching several hours. In this work, we mainly focus on the possible maximum spin period of isolated NSs/magnetars dominated by an interaction between a star's magnetic field and the disk. We find that the disk wind plays an important role in spin evolution, whose influence varies the power-law index in the evolution equation of mass flow rate. For a magnetar without disk wind, the longest spin period is tens of hours. When the disk wind with a classical parameter is involved, the maximum spin period can reach hundreds of hours. But for an extremely large index of mass flow rate due to disk wind or other angular momentum extraction processes, a spin period of ~(16-160) days is still possible.

Keywords: Accretion, Radio bursts, Stellar accretion disks, Magnetars, Stellar rotation
Excitation of Polycyclic Aromatic Hydrocarbon Emission: Dependence on Size Distribution, Ionization, and Starlight Spectrum and Intensity. Using physical models, we study the sensitivity of polycyclic aromatic hydrocarbon (PAH) emission spectra to the character of the illuminating starlight, to the PAH size distribution, and to the PAH charge distribution. The starlight models considered range from the emission from a 3 Myr old starburst, rich in far-ultraviolet (FUV) radiation, to the FUV-poor spectrum of the very old population of the M31 bulge. A wide range of starlight intensities is considered. The effects of reddening in dusty clouds are investigated for different starlight spectra. For a fixed PAH abundance parameter qPAH (the fraction of the total dust mass in PAHs with &lt;103 C atoms), the fraction of the infrared power appearing in the PAH emission features can vary by a factor of two as the starlight spectrum varies from FUV-poor (M31 bulge) to FUV-rich (young starburst). We show how qPAH can be measured from the strength of the 7.7 μm emission. The fractional power in the 17 μm feature can be suppressed by high starlight intensities.

Keywords: Interstellar dust, Interstellar emissions, Dust continuum emission
A New Equation of State for Dense Hydrogen-Helium Mixtures. II. Taking into Account Hydrogen-Helium Interactions. In a recent paper, we derived a new equation of state (EOS) for dense hydrogen/helium mixtures that covers the temperature-density domain from solar-type stars to brown dwarfs and gaseous planets. This EOS is based on the so-called additive volume law and thus does not take into account the interactions between the hydrogen and helium species. In the present paper, we go beyond these calculations by taking into account H/He interactions, derived from quantum molecular dynamics simulations. These interactions, which eventually lead to H/He phase separation, become important at low temperature and high density, in the domain of brown dwarfs and giant planets. The tables of this new EOS are made publicly available.

Keywords: Stellar physics, Brown dwarfs
Resolving Structure in the Debris Disk around HD 206893 with ALMA. Debris disks are tenuous, dusty belts surrounding main-sequence stars generated by collisions between planetesimals. HD 206893 is one of only two stars known to host a directly imaged brown dwarf orbiting interior to its debris ring, in this case at a projected separation of 10.4 au. Here we resolve structure in the debris disk around HD 206893 at an angular resolution of 0"6 (24 au) and wavelength of 1.3 mm with the Atacama Large Millimeter/submillimeter Array (ALMA). We observe a broad disk extending from a radius of &lt;51 au to ${194}_{-2}^{+13}$ au. We model the disk with a continuous, gapped, and double power-law model of the surface density profile and find strong evidence for a local minimum in the surface density distribution near a radius of 70 au, consistent with a gap in the disk with an inner radius of ${63}_{-16}^{+8}$ au and width ${31}_{-7}^{+11}$ au. Gapped structure has been observed in four other debris disks-essentially every other radially resolved debris disk observed with sufficient angular resolution and sensitivity with ALMA-and could be suggestive of the presence of an additional planetary-mass companion.

Keywords: Exoplanet dynamics, Brown dwarfs, Submillimeter astronomy, Debris disks, Interferometry
Dark Matter Constraints from a Unified Analysis of Strong Gravitational Lenses and Milky Way Satellite Galaxies. Joint analyses of small-scale cosmological structure probes are relatively unexplored and promise to advance measurements of microphysical dark matter properties using heterogeneous data. Here, we present a multidimensional analysis of dark matter substructure using strong gravitational lenses and the Milky Way (MW) satellite galaxy population, accounting for degeneracies in model predictions and using covariances in the constraining power of these individual probes for the first time. We simultaneously infer the projected subhalo number density and the half-mode mass describing the suppression of the subhalo mass function in thermal relic warm dark matter (WDM), Mhm, using the semianalytic model Galacticus to connect the subhalo population inferred from MW satellite observations to the strong lensing host halo mass and redshift regime. Combining MW satellite and strong lensing posteriors in this parameter space yields Mhm &lt; 107.0 M⊙ (WDM particle mass mWDM &gt; 9.7 keV) at 95% confidence and disfavors Mhm = 107.4 M⊙ (mWDM = 7.4 keV) with a 20:1 marginal likelihood ratio, improving limits on mWDM set by the two methods independently by ~30%. These results are marginalized over the line-of-sight contribution to the strong lensing signal, the mass of the MW host halo, and the efficiency of subhalo disruption due to baryons and are robust to differences in the disruption efficiency between the MW and strong lensing regimes at the ~10% level. This work paves the way for unified analyses of next-generation small-scale structure measurements covering a wide range of scales and redshifts.

Keywords: Milky Way dark matter halo, Strong gravitational lensing, Galaxy abundances, Dark matter