Sazuna/UAT_keywords huggingface dataset:
The Accretion History of AGN: The Spectral Energy Distributions of X-Ray-luminous Active Galactic Nuclei. Spectral energy distributions (SEDs) from X-ray to far-infrared (FIR) wavelengths are presented for a sample of 1246 X-ray-luminous active galactic nuclei (AGNs; L 0.5-10 keV &gt; 1043 erg s-1), with z spec &lt; 1.2, selected from Stripe 82X, COSMOS, and GOODS-N/S. The rest-frame SEDs show a wide spread (~2.5 dex) in the relative strengths of broad continuum features at X-ray, ultraviolet (UV), mid-infrared (MIR), and FIR wavelengths. A linear correlation (log-log slope of 0.7 ± 0.04) is found between L MIR and L X. There is significant scatter in the relation between the L UV and L X owing to heavy obscuration; however, the most luminous and unobscured AGNs show a linear correlation (log-log slope of 0.8 ± 0.06) in the relation above this scatter. The relation between L FIR and L X is predominantly flat, but with decreasing dispersion at L X &gt; 1044 erg s-1. The ratio between the "galaxy-subtracted" bolometric luminosity and the intrinsic L X increases from a factor of ~10 to 70 from log L bol/(erg s-1) = 44.5 to 46.5. Characteristic SED shapes have been determined by grouping AGNs based on relative strengths of the UV and MIR emission. The average L 1μm is constant for the majority of these SED shapes, while AGNs with the strongest UV and MIR emission have elevated L 1μm, consistent with the AGN emission dominating their SEDs at optical and near-infrared wavelengths. A strong correlation is found between the SED shape and both the L X and L bol, such that L bol/L X = 20.4 ± 1.8, independent of the SED shape. This is consistent with an evolutionary scenario of increasing L bol with decreasing obscuration as the AGN blows away circumnuclear gas.

Keywords: AGN host galaxies, Surveys, X-ray active galactic nuclei, Active galactic nuclei, Spectral energy distribution
The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling. We propose a general principle that under radiative-convective equilibrium, the spatial and temporal variations in a planet's surface and atmosphere tend to increase its cooling. This principle is based on Jensen's inequality and the curvature of the response functions of surface temperature and outgoing cooling flux to changes in incoming stellar flux and atmospheric opacity. We use an analytical model to demonstrate that this principle holds for various planet types: (1) on an airless planet, the mean surface temperature is lower than its equilibrium temperature; (2) on terrestrial planets with atmospheres, the inhomogeneity of incoming stellar flux and atmospheric opacity reduces the mean surface temperature; (3) on giant planets, inhomogeneously distributed stellar flux and atmospheric opacity increase the outgoing infrared flux, cooling the interior. Although the inhomogeneity of visible opacity might sometimes heat the atmosphere, the effect is generally much smaller than the inhomogeneous cooling effect of infrared opacity. Compared with the homogeneous case, the mean surface temperature on inhomogeneous terrestrial planets can decrease by more than 20%, and the internal heat flux on giant planets can increase by over an order of magnitude. Despite simplifications in our analytical framework, the effect of stellar flux inhomogeneity appears to be robust, while further research is needed to fully understand the effects of opacity inhomogeneity in more realistic situations. This principle impacts our understanding of planetary habitability and the evolution of giant planets using low-resolution and one-dimensional frameworks that may have previously overlooked the role of inhomogeneity.

Keywords: Atmospheric evolution, Planetary atmospheres, Exoplanet atmospheres
The Inhomogeneity Effect. II. Rotational and Orbital States Impact Planetary Cooling. We generalize the theory of the inhomogeneity effect to enable comparison among different inhomogeneous planets. A metric of inhomogeneity based on the cumulative distribution function is applied to investigate the dependence of planetary cooling on previously overlooked parameters. The mean surface temperature of airless planets increases with rotational rate and surface thermal inertia, which bounds the value in the tidally locked configuration and the equilibrium temperature. Using an analytical model, we demonstrate that the internal heat flux of giant planets exhibits significant spatial variability, primarily emitted from the nightside and high-latitude regions acting as radiator fins. Given a horizontally uniform interior temperature in the convective zone, the outgoing internal flux increases up to several folds as the inhomogeneity of the incoming stellar flux increases. The enhancement decreases with increasing heat redistribution through planetary dynamics or rotation. The outgoing internal flux on rapidly rotating planets generally increases with planetary obliquity and orbital eccentricity. The radiative timescale and true anomaly of the vernal equinox also play significant roles. If the radiative timescale is long, the outgoing internal flux shows a slightly decreasing but nonlinear trend with obliquity. Our findings indicate that rotational and orbital states greatly influence the cooling of planets and impact the interior evolution of giant planets, particularly for tidally locked planets and planets with high eccentricity and obliquity (such as Uranus), as well as the spatial and temporal variations of their cooling fluxes.

Keywords: Atmospheric evolution, Planetary atmospheres, Exoplanet atmospheres
The Inhomogeneity Effect. III. Weather Impacts on the Heat Flow of Hot Jupiters. The interior flux of a giant planet impacts atmospheric motion, and the atmosphere dictates the interior's cooling. Here we use a non-hydrostatic general circulation model (Simulating Non-hydrostatic Atmospheres on Planets) coupled with a multi-stream multi-scattering radiative module (High-performance Atmospheric Radiation Package) to simulate the weather impacts on the heat flow of hot Jupiters. We found that the vertical heat flux is primarily transported by convection in the lower atmosphere and regulated by dynamics and radiation in the overlying radiation-circulation zone. The temperature inversion occurs on the dayside and reduces the upward radiative flux. The atmospheric dynamics relay the vertical heat transport until the radiation becomes efficient in the upper atmosphere. The cooling flux increases with atmospheric drag due to increased day–night contrast and spatial inhomogeneity. The temperature dependence of the infrared opacity greatly amplifies the opacity inhomogeneity. Although atmospheric circulation could transport heat downward in a narrow region above the radiative-convective boundary, the opacity inhomogeneity effect overcomes the dynamical effect and leads to a larger overall interior cooling than the local simulations with the same interior entropy and stellar flux. The enhancement depends critically on the equilibrium temperature, drag, and atmospheric opacity. In a strong-drag atmosphere hotter than 1600 K, a significant inhomogeneity effect in three-dimensional (3D) models can boost interior cooling several-fold compared to the 1D radiative-convective equilibrium models. This study confirms the analytical argument of the inhomogeneity effect in the companion papers by Zhang. It highlights the importance of using 3D atmospheric models in understanding the inflation mechanisms of hot Jupiters and giant planet evolution in general.

Keywords: Exoplanet atmospheric dynamics, Exoplanet evolution, Planetary atmospheres, Exoplanet atmospheric structure
The Polarized Cosmic Hand: IXPE Observations of PSR B1509-58/MSH 15-5<SUP>2</SUP>. We describe IXPE polarization observations of the pulsar wind nebula (PWN) MSH 15-52, the "Cosmic Hand." We find X-ray polarization across the PWN, with B-field vectors generally aligned with filamentary X-ray structures. High-significance polarization is seen in arcs surrounding the pulsar and toward the end of the "jet," with polarization degree PD &gt; 70%, thus approaching the maximum allowed synchrotron value. In contrast, the base of the jet has lower polarization, indicating a complex magnetic field at significant angle to the jet axis. We also detect significant polarization from PSR B1509-58 itself. Although only the central pulse phase bin of the pulse has high individual significance, flanking bins provide lower-significance detections and, in conjunction with the X-ray image and radio polarization, can be used to constrain rotating vector model solutions for the pulsar geometry.

Keywords: Polarimetry, Rotation powered pulsars, Pulsar wind nebulae
A Severe Challenge to the Modified Newtonian Dynamics Phenomenology in Our Galaxy. Modified Newtonian dynamics (MOND) is one of the most popular alternative theories of dark matter to explain the missing mass problem in galaxies. Although it remains controversial regarding MOND as a fundamental theory, MOND phenomenology has been shown to widely apply in different galaxies, which poses challenges to the standard Lambda cold dark matter model. In this article, we derive analytically the galactic rotation curve gradient in the MOND framework and present a rigorous analysis to examine the MOND phenomenology in our Galaxy. By assuming a benchmark baryonic disk density profile and two popular families of MOND interpolating functions, we show for the first time that the recent discovery of the declining Galactic rotation curve in the outer region (R ≈ 17-23 kpc) can almost rule out the MOND phenomenology at more than 5σ. This strongly supports some of the previous studies claiming that MOND is neither a fundamental theory nor a universal description of galactic properties.

Keywords: Modified Newtonian dynamics, Milky Way rotation
Steadiness of Coronal Heating. The EUI instrument on the Solar Orbiter spacecraft has obtained the most stable, high-resolution images of the solar corona from its orbit with a perihelion near 0.4 au. A sequence of 360 images obtained at 17.1 nm, between 2022 October 25 19:00 and 19:30 UT, is scrutinized. One image pixel corresponds to 148 km at the solar surface. The widely held belief that the outer atmosphere of the Sun is in a continuous state of magnetic turmoil is pitted against the EUI data. The observed plasma variations appear to fall into two classes. By far the dominant behavior is a very low amplitude variation in brightness (1%) in the coronal loops, with larger variations in some footpoint regions. No hints of observable changes in magnetic topology are associated with such small variations. The larger-amplitude, more rapid, rarer, and less well organized changes are associated with flux emergence. It is suggested therefore that while magnetic reconnection drives the latter, most of the active corona is heated with no evidence of a role for large-scale (observable) reconnection. Since most coronal emission-line widths are subsonic, the bulk of coronal heating, if driven by reconnection, can only be of tangentially discontinuous magnetic fields, with angles below about 0.5c  S /c A ∼ 0.3β, with β the plasma beta parameter (∼0.01) and c  S  and c A the sound and Alfvén speeds, respectively. If heated by multiple small flare-like events, then these must be ≲1021 erg, i.e., picoflares. But processes other than reconnection have yet to be ruled out, such as viscous dissipation, which may contribute to the steady heating of coronal loops over active regions.

Keywords: Solar coronal loops, Solar coronal heating, Active sun
Anomalous Response of Mercury's Magnetosphere to Solar Wind Compression: Comparison to Earth. Magnetic field intensity increases when solar wind compresses a planet's magnetosphere. The compression can be measured using the ratio of compressed magnetic fields to purely dipolar magnetic fields just inside the magnetopause. For Earth, the ratio is proportional to the subsolar standoff distance of the magnetopause. Data from in-orbit observations by the MESSENGER spacecraft indicate an opposite ratio for Mercury; the compression ratio is inversely proportional to the subsolar standoff distance. The additional magnetic fields induced by currents at the top of Mercury's core enhance the total magnetic field strength. We also evaluated differences in the subsolar standoff of Mercury's magnetopause according to the north-south polarity of the interplanetary magnetic field (IMF). Previous studies have not identified meaningful differences in subsolar standoff distance between those in northward versus southward IMF polarities for Mercury; however, we found that the difference is statistically significant at a large IMF B  Z  (15-20 nT). The magnetic reconnection that occurs behind the cusp for a large northward IMF transfers the magnetic flux to the dayside and increases the subsolar standoff distance. The eroded magnetic flux for a large southward IMF is compensated by the induced magnetic fields.

Keywords: Space plasmas, Solar wind, Solar-planetary interactions, Interplanetary magnetic fields, Planetary science, Mercury (planet), Planetary magnetospheres
Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 0614+091. We present the first joint NuSTAR and NICER observations of the ultracompact X-ray binary 4U 0614+091. This source shows quasiperiodic flux variations on the timescale of ~days. We use reflection modeling techniques to study various components of the accretion system as the flux varies. We find that the flux of the reflected emission and the thermal components representing the disk and the compact object trend closely with the overall flux. However, the flux of the power-law component representing the illuminating X-ray corona scales in the opposite direction, increasing as the total flux decreases. During the lowest flux observation, we see evidence of accretion disk truncation from roughly 6 gravitational radii to 11.5 gravitational radii. This is potentially analogous to the truncation seen in black hole low-mass X-ray binaries, which tends to occur during the low/hard state at sufficiently low Eddington ratios.

Keywords: Accretion, Neutron stars, Stellar accretion disks, X-ray binary stars, Low-mass x-ray binary stars
A Comprehensive Optical Search for Pre-explosion Outbursts from the Quiescent Progenitor of SN 2023ixf. We perform a comprehensive search for optical precursor emission at the position of SN 2023ixf using data from the DLT40, ZTF, and ATLAS surveys. By comparing the current data set with precursor outburst hydrodynamical model light curves, we find that the probability of a significant outburst within 5 yr of explosion is low, and the circumstellar material (CSM) ejected during any possible precursor outburst is likely smaller than ~0.015M ⊙. By comparing to a set of toy models, we find that, if there was a precursor outburst, the duration must have been shorter than ~100 days for a typical brightness of M  r  ≃ -9 mag or shorter than 200 days for M  r  ≃ -8 mag; brighter, longer outbursts would have been discovered. Precursor activity like that observed in the normal Type II SN 2020tlf (M  r  ≃ -11.5) can be excluded in SN 2023ixf. If the dense CSM inferred by early flash spectroscopy and other studies is related to one or more precursor outbursts, then our observations indicate that any such outburst would have to be faint and only last for days to months, or it occurred more than 5 yr prior to the explosion. Alternatively, any dense, confined CSM may not be due to eruptive mass loss from a single red supergiant progenitor. Taken together, the results of SN 2023ixf and SN 2020tlf indicate that there may be more than one physical mechanism behind the dense CSM inferred around some normal Type II supernovae.

Keywords: Red supergiant stars, Core-collapse supernovae, Type II supernovae, Stellar mass loss, Circumstellar matter
On the Theory of Ring Afterglows. Synchrotron and inverse Compton emission successfully explain the observed spectra of gamma-ray burst (GRB) afterglows. It is thought that most GRBs are products of extremely relativistic outflows and the afterglow marks the interaction of that ejecta with the surrounding matter. A faster decay of afterglow light curves at late times is indicative of nonspherical geometries, and is usually interpreted as evidence for jet geometry. Recent numerical simulations have shown that ring-like geometries are also permissible for relativistic outflows. We therefore extend the standard theory of afterglow evolution to ring geometries. An analytic prescription for the light curves and spectra produced by relativistic toroidal blast waves is presented. We compare these to their spherical and jet-like counterparts, and show that ring afterglows decay faster than spherical outflows but not as fast as jets.

Keywords: Light curves, Gamma-ray bursts, Relativistic fluid dynamics
The Origin of the Consistent Planetary Nebula Luminosity Function Bright-end Cutoff. The [O III] 5007 Å line is typically the brightest line in planetary nebula (PN) spectra. Observations show that the brightest [O III] 5007 Å PN in a galaxy-the planetary nebula luminosity function (PNLF) bright-end cutoff-is surprisingly independent of galaxy type. To understand the origin of this puzzling uniformity, we simulate PNe with a range of cloud and star parameters using the photoionization code CLOUDY. We find that the peak [O III] 5007 Å luminosity depends weakly on both the central stellar effective temperature at high temperature and on the total PN ejecta mass; however, the peak [O III] 5007 Å luminosity depends strongly on the central stellar luminosity and the PN dust-to-gas mass ratio. We explain these scalings physically. They imply that a higher dust-to-gas mass ratio at higher central stellar luminosity can help explain a constant bright-end cutoff in the PNLF across galaxy types. This prediction is testable with a survey of galactic PNe. The surviving remnants of double white dwarf (WD) mergers should also produce photoionized nebulae analogous to PNe. These may be preferentially present at the high luminosity end of the [O III] PLNF and could explain the existence of PNe in early-type galaxies that are more luminous in [O III] than expected from single-star evolutionary models. The presence of WD mergers in both young and old stellar populations could contribute to the uniformity of the [O III] PNLF across galaxy types; such nebulae would lack the hydrogen lines otherwise characteristic of PNe.

Keywords: White dwarf stars, Planetary nebulae, Stellar mergers
GRB 221009A with an Unconventional Precursor: A Typical Two-stage Collapsar Scenario?. As the brightest gamma-ray burst (GRB) ever detected, GRB 221009A may offer a chance that reveals some interesting features that are hidden in those bursts that are not so bright. There seems to be a very weak emission with a flux of 10-8 ~ 10-7 erg cm-2 s-1 between the first pulse (T 0 ~ T 0 + 50 s; T 0 is the trigger time) and the main burst (which appears from T 0 + 180 s). Thus, the gap time between them is not really quiescent, and the first pulse could be taken as an unconventional precursor, which may provide a peculiar case study for GRB precursor phenomena. A two-stage collapsar scenario is proposed as the most likely origin for this burst. In this model, the jet for the precursor is produced during the initial core-collapse phase, and should be weak enough not to disrupt the star when it breaks out of the envelope, so that the fallback accretion process and the forming of the disk could continue. We present an approach in which the duration and flux both provide constraints on the luminosity (L j) and the Lorentz factor at the breakout time (Γb) of this weak jet. The estimated L j ≲ 1049 erg s-1 and Γb has an order of 10, which are well consistent with the theoretical prediction. Besides, the weak emission in the gap time could be interpreted as an MHD outflow due to a magnetically driven wind during the period from the proto-neutron-star phase to the forming of the accretion disk in this scenario.

Keywords: Gamma-ray bursts
Kinematics and Collimation of the Two-sided Jets in NGC 4261: VLBI Study on Subparsec Scales. We report multifrequency VLBI studies of the subparsec scale structure of the two-sided jets in the nearby radio galaxy NGC 4261. Our analyses include new observations using the source frequency phase referencing technique with the Very Long Baseline Array at 44 and 88 GHz, as well as archival data at 15 and 43 GHz. Our results show an extended double-sided structure at 43/44 GHz and provide a clear image of the nuclear region at 88 GHz, showing a core size of ~0.09 mas and a brightness temperature of ~1.3 × 109 K. Proper motions are measured for the first time in the two-sided jets, with apparent speeds ranging from 0.31 ± 0.14 c to 0.59 ± 0.40 c in the approaching jet and 0.32 ± 0.14 c in the receding jet. The jet-to-counterjet brightness ratio allows us to constrain the viewing angle to between ~54° and 84° and the intrinsic speed to between ~0.30 c and 0.55 c. We confirm the parabolic shape of the upstream jet on both sides of the central engine, with a power-law index of 0.56 ± 0.07. Notably, the jet collimation is found to be already completed at subparsec scales, with a transition location of about 0.61 pc, which is significantly smaller than the Bondi radius of 99.2 pc. This behavior can be interpreted as the initial confinement of the jet by external pressure from either the geometrically thick, optically thin advection-dominated accretion flows or the disk wind launched from it. Alternatively, the shape transition may also be explained by the internal flow transition from a magnetically dominated to a particle-dominated regime.

Keywords: Submillimeter astronomy, Very long baseline interferometry, Low-luminosity active galactic nuclei, High angular resolution
A Broadband X-Ray Study of the Dwarf Nova SS Cyg during Quiescence and Outburst. We present a broadband X-ray study (~0.3-50 keV) of the dwarf nova SS Cyg highlighting the changes in the accretion during two phases, the quiescence and the outburst states. The investigation was based on simultaneous observations carried out with the XMM-Newton and NuSTAR telescopes in two epochs, involving medium- and high-resolution spectroscopy. Spectra were harder during quiescence (kT high ~ 22.8 keV) than the outburst (kT high ~ 8.4 keV), while the mass accretion rate increased by ~35 times in the outburst (1.7 × 1016 g s-1) as compared to quiescence. The bolometric luminosity (0.01-100.0 keV) during the outburst was dominated by a blackbody emission (kT BB ~ 28 eV) from the optically thick boundary layer (BL), and the inner edge of the accretion disk resides very close to the white-dwarf (WD) surface. X-rays from the BL are consistent with the WD having mass ${1.18}_{-0.01}^{+0.02}\,{M}_{\odot }$ . Our study conclusively confirms the presence of the reflection hump in the 10-30 keV range for both phases, which arises when X-ray photons hit colder material and undergo Compton scattering. We estimated a similarly strong reflection amplitude during quiescence (~1.25) and the outburst (~1.31), indicating both the WD surface and disk are contributing to reflection. The neutral Fe K α  line, which is correlated with Compton reflection, also showed similar strength (~80 eV) in both phases. Finally, X-rays also revealed the presence of a partial intrinsic absorber during the outburst, possibly due to an outflowing accretion disk wind.

Keywords: Cataclysmic variable stars, X-ray binary stars, Dwarf novae