Sazuna/UAT_keywords huggingface dataset:
VERITAS and Multiwavelength Observations of the Blazar B3 2247+381 in Response to an IceCube Neutrino Alert. While the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods to improve our understanding of them is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between 2022 May 20 and 2022 November 10. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet, and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is described well using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, as well as the significance of the neutrino excess being at a 3σ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation.

Keywords: Blazars, Active galaxies, Radio jets, High energy astrophysics
Let There Be Neutrons! Hadronic Photoproduction from a Large Flux of High-energy Photons. We propose that neutrons may be generated in high-energy, high-flux photon environments via photo-induced reactions on pre-existing baryons. These photohadronic interactions are expected to occur in astrophysical jets and surrounding material. Historically, these reactions have been attributed to the production of high-energy cosmic rays and neutrinos. We estimate the photoproduction off of protons in the context of gamma-ray bursts, where it is expected there will be sufficient baryonic material that may be encompassing or entrained in the jet. We show that typical stellar baryonic material, even material completely devoid of neutrons, can become inundated with neutrons in situ via hadronic photoproduction. Consequently, this mechanism provides a means for collapsars and other astrophysical sites containing substantial flux of high-energy photons to be favorable for neutron-capture nucleosynthesis.

Keywords: Gamma-ray bursts, Nucleosynthesis, R-process, Nuclear astrophysics, Compact objects
New Constraints on the Evolution of the M<SUB>H I</SUB>‑M<SUB>⋆</SUB> Scaling Relation Combining CHILES and MIGHTEE-H I Data. The improved sensitivity of interferometric facilities to the 21 cm line of atomic hydrogen (H I) enables studies of its properties in galaxies beyond the local Universe. In this work, we perform a 21 cm line spectral stacking analysis combining the MeerKAT International GigaHertz Tiered Extragalactic Exploration and COSMOS H I Large Extra-galactic Survey surveys in the COSMOS field to derive a robust H I–stellar mass relation at z ≈ 0.36. In particular, by stacking thousands of star-forming galaxies subdivided into stellar mass bins, we optimize the signal-to-noise ratio of targets and derive mean H I masses in the different stellar mass intervals for the investigated galaxy population. We combine spectra from the two surveys, estimate H I masses, and derive the scaling relation  . Our findings indicate that galaxies at z ≈ 0.36 are H I richer than those at z ≈ 0 but H I poorer than those at z ≈ 1, with a slope consistent across redshift, suggesting that stellar mass does not significantly affect H I exchange mechanisms. We also observe a slower growth rate H I relative to the molecular gas, supporting the idea that the accretion of cold gas is slower than the rate of consumption of molecular gas to form stars. This study contributes to understanding the role of atomic gas in galaxy evolution and sets the stage for future development of the field in the upcoming Square Kilometre Array era.

Keywords: Galaxy formation, Extragalactic radio sources, Emission line galaxies, Galaxy evolution, Extragalactic astronomy, Radio astronomy
Simulating a Stellar Binary Merger. II. Obtaining a Light Curve. Luminous red novae are enigmatic transient events distinguished by a rapid rise in luminosity, a plateau in luminosity, and spectra, which become redder with time. The best-observed system before, during, and after the outburst is V1309 Sco. We model a candidate V1309 Sco progenitor binary configuration (1.52 + 0.16 M⊙) using the smoothed particle hydrodynamics (SPH) code StarSmasher with a modified energy equation that implements flux-limited emission-diffusion radiative transport in a Lagrangian case. We developed an imaging technique allowing us to capture the flux an observer would measure. In this novel method, the outgoing radiative flux of each SPH particle in the observer's direction is attenuated by other particles along the path to the observer. We investigated how the light curve is affected in various models: with and without dust formation; constant, Planck, or Rosseland mean opacities; different donor star sizes; different companion star masses and types; radiative heating included in our modified energy equation; and different SPH simulation resolutions. The resulting evolution in bolometric luminosity and spectrum peak temperature is in good agreement with V1309 Sco observations. Our simulations rule out V1309 Sco models that do not assume dust formation. *See the prior work in this series (R. W. M. Hatfull et al. 2021).

Keywords: Hydrodynamical simulations, Close binary stars, Interacting binary stars, Transient sources, Radiative transfer simulations, Common envelope evolution, Common envelope binary stars
Swift Observations of Gaia BH3. We present UV and X-ray observations, obtained with the Swift Observatory, of Gaia BH3, a binary system containing a 33 M⊙ black hole discovered through Gaia astrometry. The system is well detected in all UV and optical filters (1700–6500 Å). We compare our results with the modeling of the noncollapsed component using synthetic stellar libraries, and a good agreement is found with our UV observations.

Keywords: Ultraviolet astronomy, G giant stars, Astrometric binary stars, Stellar mass black holes
A Rigorous Solution to the Superluminal Issue in the Diffusion Equation. Superluminal propagation is an intrinsic problem in the diffusion equation and has not been effectively addressed for a long time. In this work, a rigorous solution to this issue is obtained under the assumption that particles undergo a random flight process, where they move isotropically at a constant speed while experiencing random scatterings. We validate this solution by comparing it with comprehensive simulations of the random flight process and find that it significantly deviates from the solution derived from the Jüttner propagator. This solution is broadly applicable to various diffusion phenomena, such as cosmic-ray propagation. We emphasize that our rigorous solution is particularly crucial in scenarios involving burst-like particle injection, where previous phenomenological approaches to the superluminal diffusion problem may not yield accurate results.

Keywords: Galactic cosmic rays, Cosmic rays
Constraints on Evolutions of Fundamental Constants from Clustering of Fast Radio Burst Dispersion Measure. Constrained measurements of fundamental physical constants using astronomical observational data represent a powerful method for investigating potential new physics. In particular, the dispersion measure (DM) of fast radio bursts (FRBs), which probes the electron density along their propagation paths, may be influenced by the spacetime variation of the fine-structure constant α. In this study, we analyze the cross-correlation signal between foreground galaxies and the DM of background FRBs to constrain the evolution of α. Assuming large-scale structure galaxy surveys with the capabilities of the China Space Station Telescope at z = 0.15 and a mock FRB survey with NFRB = 105 at z = 0.4, we test how well α variation can be constrained, with a standard deviation of σ(Δα/α) = 0.0007 at z = 0.15. Furthermore, taking into account the nonminimal coupling between the scalar field and the electromagnetic field, the variation in α can lead to the nonconservation of the photon number along geodesics. This would result in a violation of the CDDR and affect the evolution of the cosmic microwave background (CMB) temperature. In this work, we obtain constraint results on the CDDR parameter η and the parameter β governing CMB temperature evolution at z = 0.15, yielding σ(η) = 0.0004 and σ(β) = 0.0006, respectively. Finally, we relate the variation in α to the time evolution of the proton-to-electron mass ratio, reporting a standard deviation of σ(Δμ/μ) = 0.002 at z = 0.15. Future FRB surveys hold significant potential for advancing our understanding of the evolution of fundamental physical constants.

Keywords: Cosmology, Radio transient sources
Cosmological Predictions for Minor Axis Stellar Density Profiles in the Inner Regions of Milky Way–mass Galaxies. ΛCDM cosmology predicts the hierarchical formation of galaxies, which build up mass by merger events and accreting smaller systems. The stellar halo of the Milky Way (MW) has proven to be useful a tool for tracing this accretion history. However, most of this work has focused on the outer halo where dynamical times are large and the dynamical properties of accreted systems are preserved. In this work, we investigate the inner galaxy regime, where dynamical times are relatively small and systems are generally completely phase mixed. Using the FIRE-2 and Auriga cosmological zoom-in simulation suites of MW-mass galaxies, we find the stellar density profiles along the minor axis (perpendicular to the galactic disk) within the Navarro–Frenk–White scale radii (R ≈ 15 kpc) are best described as an exponential disk with scale height &lt; 0.3 kpc and a power-law component with slope α ≈ ‑4. The stellar density amplitude and slope for the power-law component are not significantly correlated with metrics of the galaxy's accretion history. Instead, we find the stellar profiles strongly correlate with the dark matter profile. Across simulation suites, the galaxies studied in this work have a stellar-to-dark-matter mass ratio that decreases as 1/r2 along the minor axis.

Keywords: Galaxy dark matter halos, Milky Way dark matter halo, Galaxy spheroids, Galaxy structure, Galactic bulge, Galaxy bulges, Galaxy stellar halos, Milky Way Galaxy physics, Milky Way stellar halo, Milky Way Galaxy
Compton Scattering of Thermal Disk Radiation with Black Hole Disk Winds. Galactic black hole (BH) X-ray binaries (XRBs) are known to exhibit episodic outbursts, during which accretion and spectral mode distinctively transition between low/hard and high/soft state. X-ray observations during high/soft state occasionally reveal a pronounced presence of a powerful disk wind in these systems. However, it is unexplored to date how such winds may influence disk emission in that regime. In this work, we consider an observational implication by Compton scattering of thermal disk radiation due to accretion disk winds by performing multidimensional Monte Carlo simulations in the context of a stratified wind of large solid angle launched over a large radial extent of the disk. The Compton-scattered thermal disk spectrum is computed for a different wind property, i.e., wind density and its radial gradient. We find that the intrinsic disk radiation can be significantly down-scattered by winds of moderate-to-high density to the extent that the transmitted spectrum can substantially deviate from the conventional multicolor-disk emission in a tangible way. We thus claim that the conventional treatment of spectral hardening in the disk atmosphere may be insufficient to fully account for the observed disk continuum in the presence of strong wind scattering. It is suggested that the effect of scattering process (by fw) should be incorporated to accurately evaluate an intrinsic disk spectrum besides the conventional hardening (color correction) factor (by fc). We argue that BH spin measurements using thermal continuum-fitting in transient XRBs may well be mildly (if not significantly) altered by such spectral "contamination."

Keywords: X-ray astronomy, Black hole physics, Stellar mass black holes, X-ray transient sources, Computational methods, Spectroscopy, Low-mass x-ray binary stars, Astrophysical black holes
Hydrodynamic Predictions for the Next Outburst of T Coronae Borealis: It Will Be the Brightest Classical or Recurrent Nova Ever Observed in X-Rays. T Coronae Borealis (TCrB) is a recurrent nova with recorded outbursts in 1866 and 1946 and possible outbursts in 1217 and 1787. It is predicted to explode again in 2025 or 2026 based on multiple observational studies. The system consists of a massive (Mwd ≳ 1.35 M⊙) white dwarf (WD) and a red giant (M3–M4 III). We have performed 1D hydrodynamic simulations with NOVA to predict the behavior of the next outburst. These simulations consist of a range of mass accretion rates onto ∼1.35 M⊙ WDs, designed to bound the conditions necessary to achieve ignition of an explosion after an ≈80 yr interoutburst period. We have used both carbon–oxygen and oxygen–neon initial compositions, in order to include the possible ejecta abundances to be measured in the observations of the next outburst. As the WD in the TCrB system is observed to be massive, theoretical predictions reported here imply that the WD is growing in mass as a consequence of the thermonuclear runaway. Therefore, the secular evolution of the WD may allow it to approach the Chandrasekhar limit and either explode as a Type Ia supernova or undergo accretion-induced collapse, depending on its underlying composition. We have followed the evolution of just the WD, after removing the ejected matter from the surface layers. Our intent is to illuminate the mystery of the unique, second maximum in the two well-observed outbursts and we have found conditions that bracket the predictions. *R.M.W. took part in the observations and early simulations for this paper and we are grateful for his help.

Keywords: Galaxy chemical evolution, Novae, Galaxy abundances, Symbiotic novae, Recurrent novae, Cataclysmic variable stars
Evolution of Extremely Soft Binaries in Dense Star Clusters: On the Jupiter Mass Binary Objects. Star-forming regions, characterized by dense environments, experience frequent encounters that significantly influence binary systems, leading to their hardening, softening, or ionization. We extend the Hut and Bahcall formalism to derive an analytical expression for the ionization cross section in extreme mass ratio binary systems, allowing us to investigate the orbital evolution and population dynamics of binary planets and binary brown dwarfs in star clusters, while considering ongoing binary system formation. Our findings reveal that for low-mass soft binaries, the semimajor axis distribution asymptotes to a universal power law between ∝a−8/3 and ∝a−5/3 over the derived ionization timescale. We also discuss the implications of our results for the candidate Jupiter-mass binary objects putatively reported in the Trapezium cluster. We demonstrate that if their existence is verified, they likely form continuously with a spectrum proportional to a1, aligning better with the ejection mechanism than with the in situ formation mechanism, which predicts a distribution roughly proportional to a−1. However, this implies an impractically high ejection formation rate. Alternatively, if these objects are binary brown dwarfs, continuous in situ formation (∝a−1) with an initial minimal semimajor axis around 20 au and a formation rate of 100 Myr−1 plausibly matches the observed number of single objects, binary number, binary fraction, and semimajor axis distribution.

Keywords: Exoplanet dynamics, N-body simulations, Dynamical evolution
A New Reaction Rate of the <SUP>27</SUP>Al(p,γ)<SUP>28</SUP>Si Reaction Based on Indirect Low-energy Cross-section Measurements. The Mg–Al cycle is characteristic of the high-temperature (T ∼ 0.055 GK) H-burning of evolved stars and their nucleosynthesis. A proper comprehension of this reaction network can help in solving debated questions such as the occurrence of anticorrelation in Mg–Al abundances in globular clusters. Recent high-resolution surveys have shown that such an anticorrelation may hide the existence of multiple stellar populations and that the relative abundances of Mg isotopes may not be correlated with Al. Proton-induced reactions on 27Al play a key role in this respect, in particular the interplay between the (p, α) and (p, γ) channels, determining the closure (or not) of the Mg–Al cycle. Presently, the situation is still debated owing to the large uncertainty affecting existing experimental nuclear data. A recent indirect measurement indicates a further reduction in the 27Al(p, α)24Mg reaction rate with respect to the ones commonly adopted in astrophysical models. In the present work, we update the 27Al(p,γ)28Si reaction rate based on the same indirect measurement results. In the case of AGB stars experiencing hot bottom burning, the revised rate would lead to a ∼35% increase in 27Al abundance with respect to what is presently foreseen, with interesting astrophysical consequences.

Keywords: Globular star clusters, Isotopic abundances, Nuclear astrophysics
An Analytical Galactic Chemical Evolution Model with Gas Inflow and a Terminal Wind. We present a new analytical galactic chemical evolution (GCE) model with gas inflow, internally caused outflow, and extra gas loss after a period of time. The latter mimics the ram pressure stripping of a dwarf satellite galaxy near the pericenter of its orbit around a host galaxy. The new model is called Inflow with Ram Pressure Stripping (IRPS). We fit the α-element ([α/H]) distributions of the Draco, Sculptor, Fornax, Leo II, Leo I, and And XVIII dwarf spheroidal galaxies. We compared the best fits of IRPS with four other GCE models. The IRPS fits half of the galaxies in our set better than the Leaky Box, Pre-enriched, Accretion, and RPS models. Unlike previous models, none of the IRPS model parameters—not even the effective yield—correlate with galaxy properties, like luminosity. One of the IRPS parameters is the α-abundance at which stripping began. That parameter can override the effective yield in determining the galaxy's mean α-abundance.

Keywords: Dwarf spheroidal galaxies, Galaxy processes, Galaxy chemical evolution
Toward Multienergy Neutrino Astronomy: Diagnosing Enhanced Circumstellar Material around Stripped-envelope Supernovae. A novel approach is proposed to reveal a secret birth of enhanced circumstellar material (CSM) surrounding a collapsing massive star using neutrinos as a unique probe. In this scheme, nonthermal TeV-scale neutrinos produced in ejecta–CSM interactions are tied with thermal MeV neutrinos emitted from a pre-explosion burning process, based on a scenario that CSM had been formed via the presupernova activity. Taking a representative model of the presupernova neutrinos, the spectrum and light curve of the corresponding high-energy CSM neutrinos are calculated at multiple mass-loss efficiencies, which are considered as a systematic uncertainty. In addition, as a part of the method demonstration, the detected event rates along time at JUNO and IceCube, as representative detectors, are estimated for the presupernova and CSM neutrinos, respectively, and are compared with the expected background rate at each detector. The presented method is found to be reasonably applicable for the range up to ∼1 kpc and even farther with future experimental efforts. The potentialities of other neutrino detectors, such as SK-Gd, Hyper-Kamiokande, and KM3NeT, are also discussed. This is a pioneering work of performing astrophysics with neutrinos from diverse energy regimes, initiating multienergy neutrino astronomy in the forthcoming era where next-generation large-scale neutrino telescopes are operating.

Keywords: Supernova neutrinos, High energy astrophysics, Core-collapse supernovae, Massive stars, Neutrino astronomy, Circumstellar matter
Prospects for Observing Astrophysical Transients with Gigaelectronvolt Neutrinos. Although Cherenkov detectors of high-energy neutrinos in ice and water are often optimized to detect teraelectronvolt–petaelectronvolt neutrinos, they may also be sensitive to transient neutrino sources in the 1–100 GeV energy range. A wide variety of transient sources have been predicted to emit gigaelectronvolt neutrinos. In light of the upcoming IceCube Upgrade, which will extend the IceCube detector's sensitivity down to a few gigaelectronvolts, as well as improve its angular resolution, we survey a variety of transient-source models and compare their predicted neutrino fluences to detector sensitivities, in particular those of IceCube-DeepCore and the IceCube Upgrade. We consider ranges of neutrino fluence from transients powered by nonrelativistic shocks, such as novae, supernovae, fast blue optical transients, and tidal disruption events. We also consider fast radio bursts and relativistic outflows of high- and low-luminosity gamma-ray bursts. Our study sheds light on the prospects of observing gigaelectronvolt transients with existing and upcoming neutrino facilities.

Keywords: Particle astrophysics
ULX Collimation by Outflows in Moderately Magnetized Neutron Stars. We perform radiative magnetohydrodynamics simulations in general relativity of super-Eddington disk accretion onto neutron stars endowed with a magnetic dipole corresponding to surface strengths not exceeding 100 Giga-Gauss. Accretion is found to power strong outflows that collimate the emergent radiation of the accretion columns, leading to apparent radiative luminosities of ∼100 Eddington, when the true luminosity is a few Eddington units. Surprisingly, the collimation cone/angle widens with increasing magnetic field. Thus, in our simulations the apparent luminosity of the neutron star is substantially larger for the weaker magnetic fields (1010 G) than for the stronger ones (1011 G). We conclude that a super-Eddington accreting neutron star with dipole magnetic field on the order of 1010 G is the most likely source of ultraluminous X-rays.

Keywords: Neutron stars, Ultraluminous x-ray sources, Magnetohydrodynamical simulations