Sazuna/UAT_keywords huggingface dataset:
Understanding the Broad-line Region of Active Galactic Nuclei with Photoionization. I. The Moderate-accretion Regime. Over three decades of reverberation mapping (RM) studies on local broad-line active galactic nuclei (AGNs) have measured reliable black hole (BH) masses for &gt;100 AGNs. These RM measurements reveal a significant correlation between the Balmer broad-line region (BLR) size and AGN optical luminosity (the R–L relation). Recent RM studies for AGN samples with more diverse BH parameters (e.g., mass and Eddington ratio) reveal a substantial intrinsic dispersion around the average R–L relation, suggesting that variations in the broadband spectrum, driven by accretion parameters and other factors such as the cloud distribution and inclination, significantly influence the measured R–L relation. Here we perform a detailed photoionization investigation of expected broad-line properties as functions of accretion parameters using AGN continuum models from qsosed. We compare theoretical predictions with observations of a sample of 67 z ≲ 0.5 reverberation-mapped AGNs with rest-frame optical and UV spectra in the moderate-accretion regime (Eddington ratio λEdd ≡ L/LEdd &lt; 0.5). The UV/optical line strengths and their dependences on accretion parameters are reasonably well reproduced by the locally optimally emitting cloud photoionization models. We provide quantitative recipes using optical/UV line flux ratios to infer the unobservable ionizing continuum. Additionally, photoionization models with universal values of ionization parameter ( ) and hydrogen density ( ) can qualitatively reproduce the observed global R–L relation for the current RM AGN sample. However, such models fail to reproduce the observed decrease in BLR size with increasing L/LEdd at fixed optical luminosity, implying that gas density or BLR structure may systematically change with accretion rate.

Keywords: Black hole physics, Active galactic nuclei, Quasars
Hooks, Lines, and Sinkers: How Active Galactic Nucleus Feedback and Cosmic-Ray Transport Shape the Far-infrared–Radio Correlation of Galaxies. The far-infrared–radio correlation (FRC) is one of the most promising empirical constraints on the role of cosmic rays (CRs) and magnetic fields in galaxy formation and evolution. While many theories have been proposed in order to explain the emergence and maintenance of the FRC across a gamut of galaxy properties and redshift, the nonlinear physics at play remain unexplored in full complexity and within a cosmological context. We present the first reproduction of the z ∼ 0 FRC using detailed synthetic observations of state-of-the-art cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE-3) suite with explicitly evolved CR proton and electron (CRe) spectra, for three models for CR transport and multichannel active galactic nucleus (AGN) feedback. In doing so, we generally verify the predictions of "calorimeter" theories at high FIR luminosities (L60 μm ≳ 109.5 L⊙) and at low FIR luminosities (L60 μm ≲ 109.5 L⊙), the so-called "conspiracy" of increasing UV radiation escape in tandem with increasing CRe escape, and find that the global FRC is insensitive to orders-of-magnitude locally variable CR transport coefficients. Importantly, the indirect effect of AGN feedback on emergent observables highlights novel interpretations of outliers in the FRC. In particular, we find that in many cases "radio-excess" objects can be better understood as "IR-dim" objects with longer-lived radio contributions at low z from Type Ia supernovae and intermittent black hole accretion in quenching galaxies, though this is sensitive to the interplay of CR transport and AGN feedback physics. This creates characteristic evolutionary tracks leading to the z = 0 FRC, which shape the subsequent late-time behavior of each model.

Keywords: Extragalactic magnetic fields, Stellar feedback, Cosmic rays, Active galactic nuclei, Radiative transfer simulations, Galaxies, Magnetohydrodynamical simulations
Multimessenger Probes of Supermassive Black Hole Spin Evolution. Using the semianalytic model SEROTINA, we investigate the cosmic spin evolution of supermassive black holes (SMBHs) incorporating recent results from general-relativistic magnetohydrodynamics simulations of spin-down from relativistic jets. We compare several variations of our model with compiled black hole (BH) spin measurements derived from X-ray reflection spectroscopy, correcting for a bias arising from the spin-dependent radiative efficiency of accretion flows. We show that the observed spin distribution is in agreement with a model that includes jet-driven spin-down, a key mechanism that acts to modulate spins across cosmic time at both high and very low specific accretion rates. The data also clearly prefer models with coherent accretion over models in which accretion disks rapidly switch from prograde to retrograde. We further predict spin distributions accessible via spatially resolved event horizons by the next-generation Event Horizon Telescope and Black Hole Explorer, as well as gravitational waves by the Laser Interferometer Space Antenna (LISA), each of which offers unique and distinct windows into the population of spinning BHs. Jet-driven spin-down is most strongly imprinted on the abundance of very highly spinning objects in our model. In addition, we show that the spin distribution sampled by LISA events may contain a signature of the natal spin distribution of heavy seeds, but not of light seeds, offering additional discrimination between these seeding pathways. Spin distributions from these future observed samples can be used to constrain the detailed physical properties of the accretion flow on horizon scales around SMBHs.

Keywords: Supermassive black holes, Relativistic jets, Active galactic nuclei, Kerr black holes
Propagation of Interplanetary Shocks in the Inner Heliosphere. Interplanetary (IP) shocks are one of the crucial dynamic phenomena in the heliosphere. They can accelerate particles to high energies, generate plasma waves, and trigger geomagnetic storms in Earth's magnetosphere, significantly impacting technological infrastructure. In this study, two IP shock events are selected to study the temporal variations of the shock parameters using magnetometer and ion plasma measurements from STEREO-A and B, the Wind, Cluster fleet, and the Advanced Composition Explorer spacecraft. The shock normal vectors are determined using minimum variance analysis and magnetic coplanarity methods. During the 2007 May 7 event, the shock parameters and the shock normal direction remain consistent across each spacecraft crossing of the shock. The shock surface appears to be tilted by almost the same degree as the Parker spiral, and the driver could be a corotating interaction region (CIR). During the 2007 April 23 event, the shock parameters do not change significantly except for the shock angle θBn; however, the shape of the IP shock appears to be twisted in the direction perpendicular to the Sun–Earth line as well. The driver of this rippled shock is a stream interaction region/CIR as well.

Keywords: Solar wind, Interplanetary shocks, Planetary magnetospheres, Magnetic storms
JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at z ∼ 7─14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe. We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7─14. Our sample is composed of 60 galaxies at zspec ∼ 7─14, including recently confirmed galaxies at zspec = 12.34─14.18 with JWST, as well as new confirmations at zspec = 6.583─7.643 with −24 &lt; MUV &lt; −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10─13 identified from ground-based telescope images before JWST are passive galaxies at z ∼ 3─4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z &gt; 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that ∼70% of the bright galaxies at z ∼ 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z ≳ 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N IV]λ1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z ≳ 10 and are responsible for their overabundance.

Keywords: Galaxy formation, High-redshift galaxies, Galaxy evolution
Maximum-likelihood Regression with Systematic Errors for Astronomy and the Physical Sciences. I. Methodology and Goodness-of-fit Statistic of Poisson Data. This paper presents a new statistical method that enables the use of systematic errors in the maximum-likelihood regression of integer-count Poisson data to a parametric model. The method is primarily aimed at the characterization of the goodness-of-fit statistic in the presence of the over-dispersion that is induced by sources of systematic error, and is based on a quasi-maximum-likelihood method that retains the Poisson distribution of the data. We show that the Poisson deviance, which is the usual goodness-of-fit statistic and that is commonly referred to in astronomy as the Cash statistics, can be easily generalized in the presence of systematic errors, under rather general conditions. The method and the associated statistics are first developed theoretically, and then they are tested with the aid of numerical simulations and further illustrated with real-life data from astronomical observations. The statistical methods presented in this paper are intended as a simple general-purpose framework to include additional sources of uncertainty for the analysis of integer-count data in a variety of practical data analysis situations.

Keywords: Measurement error model, Regression, Astrostatistics, Poisson distribution, Parametric hypothesis tests, Maximum likelihood estimation
Maximum-likelihood Regression with Systematic Errors for Astronomy and the Physical Sciences. II. Hypothesis Testing of Nested Model Components for Poisson Data. A novel model of systematic errors for the regression of Poisson data is applied to hypothesis testing of nested model components with the introduction of a generalization of the ΔC statistic that applies in the presence of systematic errors. This paper shows that the null-hypothesis parent distribution of this ΔCsys statistic can be obtained either through a simple numerical procedure, or in a closed form by making certain simplifying assumptions. It is found that the effects of systematic errors on the test statistic can be significant, and therefore the inclusion of sources of systematic errors is crucial for the assessment of the significance of the nested model component in practical applications. The methods proposed in this paper provide a simple and accurate means of including systematic errors for hypothesis testing of nested model components in a variety of applications.

Keywords: Astrostatistics
Early Detection of Multiwavelength Blazar Variability. Blazars are a subclass of active galactic nuclei with relativistic jets pointing toward the observer. They are notable for their flux variability at all observed wavelengths and timescales. Together with simultaneous measurements at lower energies, the very-high-energy (VHE) emission observed during blazar flares may be used to probe the population of accelerated particles. However, optimally triggering observations of blazar high states can be challenging. Notable examples include identifying a flaring episode in real time and predicting VHE flaring activity based on lower-energy observables. For this purpose, we have developed a novel deep learning analysis framework, based on data-driven anomaly detection techniques. It is capable of detecting various types of anomalies in real-world, multiwavelength light curves, ranging from clear high states to subtle correlations across bands. Based on unsupervised anomaly detection and clustering methods, we differentiate source variability from noisy background activity, without the need for a labeled training data set of flaring states. The framework incorporates measurement uncertainties and is robust given data quality challenges, such as varying cadences and observational gaps. We evaluate our approach using both historical data and simulations of blazar light curves in two energy bands, corresponding to sources observable with the Fermi Large Area Telescope and the upcoming Cherenkov Telescope Array Observatory. In a statistical analysis, we show that our framework can reliably detect known historical flares.

Keywords: Neural networks, Blazars, Outlier detection, Transient detection, Extragalactic astronomy, Gamma-ray astronomy, Astronomical methods
A Multiwavelength Light-curve Analysis of the Classical Nova KT Eri: Optical Contribution from a Large Irradiated Accretion Disk. KT Eri is a classical nova that went into outburst in 2009. Recent photometric analysis in quiescence indicates a relatively longer orbital period of 2.6 days, so that KT Eri could host a very bright accretion disk during the outburst like in the recurrent nova U Sco, the orbital period of which is 1.23 days. We reproduced the optical V light curve as well as the supersoft X-ray light curve of KT Eri in outburst, assuming a large irradiated disk during a nova wind phase of the outburst while a normal size disk after the nova winds stop. This result is consistent with the temporal variation of wide-band V brightness that varies almost with the intermediate-band Strömgren y brightness, because the V flux is dominated by continuum radiation, the origin of which is a photospheric emission from the very bright disk. We determined the white dwarf mass to be MWD = 1.3 ± 0.02 M⊙, the hydrogen-burning turnoff epoch to be ∼240 days after the outburst, the distance modulus in the V band to be (m ‑ M)V = 13.4 ± 0.2, and the distance to KT Eri to be d = 4.2 ± 0.4 kpc for the reddening of E(B ‑ V) = 0.08. The peak absolute V brightness is about   and the corresponding recurrence time is ∼3000 yr from its ignition mass together with the mean mass-accretion rate of   yr‑1 in quiescence. Thus, we suggest that KT Eri is not a recurrent nova.

Keywords: X-ray astronomy, Fast novae, Stellar winds, Shocks, Classical novae
Thermal Spectra of Warped and Broken Accretion Disks. Black holes may accrete gas with angular momentum vectors misaligned with the black hole spin axis. The resulting accretion disks are subject to Lense–Thirring precession, and hence torque. Analytical calculations and simulations show that Lense–Thirring precession will warp, and, for large misalignments, fracture the disk. In GRMHD simulations, the warping or breaking occurs at ≲10 rs, where rs is the Schwarzschild radius. Considering that accretion disk spectra in the soft state of stellar-mass black holes are generally well modeled as multicolor blackbodies, the question arises as to how consistent warped and broken disks are with observations. Here, we analytically calculate thermal spectra of warped and broken disks with a warp or break radius at 10 rs for various disk inclinations. Due to self-irradiation and the projected area of the inclined disk regions, the spectra of inclined disks significantly deviate from multicolor blackbodies and do not follow the multicolor blackbody relation νLν ∝ νγ = ν4/3 at low frequencies ν. The power-law indices at low frequencies of the inclined disks vary with viewing angle; when viewed face-on, they vary between γ ≈ 0.91 and 1.26 for the warped disks and γ ≈ 1.37–1.54 for the broken disks depending on the inclination angle. The differences decrease when moving the location of the disk warp and break to larger radii; for inclined disks to emit as multicolor blackbodies, they must warp or break at radii ≥50 rs. Our results imply that accretion disks around black holes in the soft state warp or break at larger radii than suggested in GRHMD simulations.

Keywords: Accretion, Stellar mass black holes
Continuous Gravitational Waves from Thermal Mountains on Accreting Neutron Stars: Effect of the Nuclear Pasta Phase. As density increases, the shape of nuclei transitions to nonspherical "nuclear pasta" structures. The physical properties of the nuclear pasta, such as thermal conductivity and elasticity, have implications for detecting continuous gravitational waves from a rapidly rotating neutron star. In this work, we investigate the effect of the nuclear pasta on the quadruple moment, and find out that, compared with previous work, the quadrupole moment contributing to continuous gravitational-wave radiation can be up to 2 orders of magnitude larger. We also discuss the relationship between the quadruple moment and the maximum shear strain. Considering the properties of nuclear pasta, we study the detectability of known accreting neutron stars and compare predicted results to the detectable amplitude limits. These sources are well above the sensitivity curves for Cosmic Explorer and Einstein Telescope detectors. Our work advances the understanding of the properties of nuclear pasta and a possible mechanism for continuous gravitational waves.

Keywords: Neutron stars, Low-mass x-ray binary stars, Gravitational waves
What Drives the H I Content of Central Galaxies—A Comparison between Hydrodynamic Simulations and Observations Using Random Forest. We investigate the driving mechanisms for the H I gas content in star-forming central galaxies at low redshift, by examining the H I-to-stellar mass ratio (MH I/M*) in both the state-of-the-art hydrodynamic simulations, IllustrisTNG (TNG) and EAGLE, and the xGASS sample. We quantify the correlations of MH I/M* with a variety of galaxy properties using the Random Forest regression technique, and we make comparisons between the two simulations, as well as between the simulations and xGASS. Gas-phase metallicity is found to be most important in both simulations, but is ranked mildly for xGASS, suggesting that metals and gas driven by feedback effects in real galaxies is not as tightly coupled as in the simulations. Beyond that, the accretion rate of supermassive black holes is the most important feature in TNG, while specific star formation rate is the top ranked in EAGLE. This result can be understood from the fact that the H I gas is regulated mainly by thermal-mode AGN feedback in TNG and by stellar feedback in EAGLE. Although neither simulation can fully reproduce the feature importance obtained for real galaxies in the xGASS, EAGLE performs better than TNG in the sense that the observationally top-ranked property, u ‑ r, is also highly ranked in EAGLE. This result implies that stellar feedback plays a more dominant role than AGN feedback in driving the H I gas content of low-redshift galaxies.

Keywords: Hydrodynamical simulations, Galaxy dark matter halos, Interstellar atomic gas, Neutral hydrogen clouds, Galaxy evolution, Galaxies
The Impact of Bar-induced Noncircular Motions on the Measurement of Galactic Rotation Curves. We study the impact of bar-induced noncircular motions on the derivation of galactic rotation curves (RCs) using hydrodynamic simulations and observational data from the PHANGS-ALMA survey. We confirm that noncircular motions induced by a bar can significantly bias RCs derived from the conventional tilted-ring method, consistent with previous findings. The shape of the derived RC depends on the difference in position angle (Δϕ) between the major axes of the bar and the disk in the face-on plane. For  , noncircular motions produce a bar-induced "dip" feature (rise–drop–rise pattern) in the derived RC, which shows higher velocities near the nuclear ring and lower velocities in the bar region compared to the true RC (RCtrue). We demonstrate convincingly that such dip features are very common in the PHANGS-ALMA sample of barred galaxies. Hydrodynamical simulations reveal that the "dip" feature is caused by the perpendicular orientation of the gas flows in the nuclear ring and the bar; at low   streamlines in the nuclear ring tend to enhance Vlos, while those in the bar tend to suppress Vlos. We use a simple "misaligned ellipses" model to qualitatively explain the general trend of RCs from the tilted-ring method (RCtilted) and the discrepancy between RCtilted and RCtrue. Furthermore, we propose a straightforward method to implement a first-order correction to the RC derived from the tilted-ring method. Our study is the first to systematically discuss the bar-induced "dip" feature in the RCs of barred galaxies by combining both simulations and observations.

Keywords: Hydrodynamical simulations, Galaxy rotation curves, Barred spiral galaxies, Galaxy dynamics
Kinetic and Photochemical Disequilibrium in the Potentially Carbon-rich Atmosphere of the Warm Jupiter WASP-69 b. High-resolution transmission spectroscopy of the warm gas giant WASP-69 b has revealed the presence of H2O, CO, CH4, NH3, and C2H2 in its atmosphere. This study investigates the impact of vertical diffusion and photochemistry on its atmospheric composition, with a focus on the detected species plus HCN and CO2, to constrain the atmospheric C/O ratio. We utilize nonequilibrium gas-phase simulations to conduct a parameter study for vertical diffusion strength, local gas temperature, and C/O ratio. Our results indicate that a carbon-rich atmosphere enhances CH4 and C2H2 concentrations, while NH3 undergoes chemical conversion into HCN in carbon-rich, high-temperature environments. Consequently, HCN is abundantly produced in such atmospheres, though its strong spectral features remain undetected in WASP-69 b. Photochemical production of HCN and C2H2 is highly sensitive to vertical diffusion strength, with weaker diffusion resulting in higher concentrations. Cross-correlation of synthetic spectra with observed data shows that models with C/O = 2 best match observations, but models with C/O = 0.55 and 0.9 lead to statistically equivalent fits, leaving the C/O ratio unconstrained. We highlight the importance of accurately modeling NH3 quenching at pressures greater than 100 bars. Models for WASP-69 b capped at 100 bars bias cross-correlation fits toward carbon-rich values. We suggest that if the atmosphere of WASP-69 b is indeed carbon-rich with a solar metallicity, future observations should reveal the presence of HCN.

Keywords: Planetary atmospheres, Exoplanet atmospheres, Chemical kinetics