Sazuna/UAT_keywords huggingface dataset:
Deciphering Radio Emissions from Accretion Disk Winds in Radio-quiet Active Galactic Nuclei. Unraveling the origins of radio emissions from radio-quiet active galactic nuclei (RQ AGNs) remains a pivotal challenge in astrophysics. One potential source of this radiation is the shock interaction between AGN disk winds and the interstellar medium (ISM). To understand this phenomenon, we construct a spherical, one-zone, and self-similar expansion model of shock structure between ultrafast outflows (UFOs) and the ISM. We then calculate the energy density distribution of nonthermal electrons by solving the transport equation, considering diffusive shock acceleration as the acceleration mechanism and synchrotron and inverse Compton cooling as the cooling mechanisms. Based on the derived energy distribution of nonthermal electrons, we model the radio synchrotron spectrum of the shocked ISM. For the 15 nearby RQ AGNs hosting UFOs, we investigate the shocked ISM parameters required to model their observed radio spectra based on X-ray observations and measured UFO velocities. Radio spectra of 11 out of 15 nearby RQ AGNs would be explained by the AGN disk wind model. This is a compelling indication that shock interactions between AGN disk winds and the ISM could indeed be the source of their radio emissions. The typical predicted source size and magnetic field strength are several 100 pc and 0.1 mG, respectively. We also discuss whether our prediction can be tested by future radio observations.

Keywords: High energy astrophysics, Extragalactic radio sources, Seyfert galaxies, Non-thermal radiation sources, Active galactic nuclei
Finding Candidate TeV Halos among Very-high-energy Sources. We search for possible pulsar TeV halos among the very-high-energy (VHE) sources reported in different VHE surveys, among which in particular we use the results from the first Large High Altitude Air Shower Observatory catalog of γ-ray sources. Six candidates are found. They share similar properties of containing a middle-aged, γ-ray–bright pulsar in their positional error circles (the respective pulsars are J0248+6021, J0359+5414, J0622+3749, J0633+0632, J2006+3102, and J2238+5903), being in a rather clean field without any common Galactic VHE-emitting supernova remnants or (bright) pulsar wind nebulae (PWNe), and showing an absence of any γ-ray emissions in 0.1–500 GeV after removing the pulsars' emissions. Combining these candidates with several reported (candidate) TeV halos, we obtain relationships between their luminosity at 50 TeV (L 50TeV) and the corresponding pulsars' spin-down energy ( Ė ), which are  L50TeV∼Ė0.9  and  L50TeV/Ė∼6.4×10‑4 , respectively. The relationships are nearly identical to previously reported ones. We probe possible connections between the extent/sizes of the VHE sources and the pulsars' ages, and find a weak older-and-smaller trend. By comparing to the VHE detection results for PWNe, it is clear that the (candidate) TeV halos have hard emissions by either having power-law indices smaller than 2 in 1–25 TeV or by only being detected in 25–100 TeV. In addition, we also consider seven other VHE sources as possible TeV halos based on the results from different studies of them, but they do not fit cleanly with the properties listed above, indicating their potentially complex nature.

Keywords: Gamma-rays, Pulsars
Large-scale Overdensity of Lyman Break Galaxies around the z = 6.3 Ultraluminous Quasar J0100 + 2802. We study the environment of the z = 6.33 ultraluminous quasar SDSS J010013.02+280225.8 (J0100) to understand its association with large-scale structure. Theoretical models propose high-redshift quasars as markers of galaxy overdensities residing in the most massive dark matter halos (DMHs) in the early Universe. J0100 is an ultraluminous quasar with the most massive black hole known at z ≳ 6, suggesting a high likelihood of residing in a massive DMH. We present wide-field (∼522 arcmin2) imaging in the r, i, and z bands from the Large Binocular Cameras on the Large Binocular Telescope, with Y- and J-band imaging from the Wide-field Infrared Camera on the Canada–France–Hawaii Telescope, centered on J0100. Applying color selections, we identify 23 objects as i-dropout Lyman break galaxy (LBG) candidates in the J0100 field. We use the deep photometric catalog in the 1.27 deg2 COSMOS field to calculate the density of LBGs in a blank field, and to estimate the selection completeness and purity. The observed surface density of LBG candidates in the J0100 field corresponds to a galaxy overdensity of δ = 4 (at 8.4σ). This large-scale overdensity suggests that the ∼22 arcmin2 overdensity found by Kashino et al. using JWST data extends out to much larger scales. We calculate the angular autocorrelation function of the candidates and find a positive correlation on ≲10‧ scales as well as evidence of asymmetries in their spatial distribution, further suggesting the direct detection of large-scale structure in the field of the ultraluminous quasar J0100.

Keywords: Large-scale structure of the universe, High-redshift galaxy clusters, Quasars, Lyman-break galaxies, High-redshift galaxies
Investigating the Unique Drift Behavior of PSR B2110+27 with FAST. Careful scrutiny of the single pulse emissions from PSR B2110+27 has been conducted through highly sensitive observations using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) at a central frequency of 1250 MHz. Our investigation revealed significant subpulse drift behavior and nulling in this pulsar. Moreover, we observed that the nulling events tend to be of short duration, with an estimated overall nulling fraction of approximately 27% ± 3%. It is noteworthy that the drift direction of the subpulses exhibits abrupt changes, occasionally transitioning into a steady state or displaying a low drift rate. Analysis using longitude resolved fluctuation spectra indicates the presence of two distinct repetition periods for the pulsar: P 3 = (10.8 ± 2.5)P and P 3 = (31.6 ± 4.2)P, where P denotes the pulsar period. Our investigation revealed that the subpulse separation remains consistent across different drift patterns, with P 2 = 2.°3 ± 0.°2. A more comprehensive analysis indicates that the unique drift behavior observed can be explained by a carousel model of the dipole field. Minor changes in P 2 and drift rate caused significant variations in the apparent P 3 and abrupt shifts in the drift direction, while the true repetition period (assuming first-order aliasing) changed by only ∼10%. We observe a drift band memory and apparent phase memory across the null state in this pulsar, as well as variations in the drift rate and drift direction across the null state, though we have not detected significant periodicity of the nulling itself. This suggests that these phenomena may arise from random null pulses intersecting with the frequently aliased drift bands.

Keywords: Radio pulsars
Constraints on the Spacetime Variation of the Fine-structure Constant Using DESI Emission-line Galaxies. We present strong constraints on the spacetime variation of the fine-structure constant α using the Dark Energy Spectroscopic Instrument (DESI). In this pilot work, we utilize ∼110,000 galaxies with strong and narrow [O III] λ λ4959, 5007 emission lines to measure the relative variation Δα/α in space and time. The [O III] doublet is arguably the best choice for this purpose owing to its wide wavelength separation between the two lines and its strong emission in many galaxies. Our galaxy sample spans a redshift range of 0 &lt; z &lt; 0.95, covering half of all cosmic time. We divide the sample into subsamples in 10 redshift bins (Δz = 0.1), and calculate Δα/α for the individual subsamples. The uncertainties of the measured Δα/α are roughly between 2 × 10‑6 and 2 × 10‑5. We find an apparent α variation with redshift at a level of Δα/α = (2–3) × 10‑5. This is highly likely to be caused by systematics associated with wavelength calibration, since such small systematics can be caused by a wavelength distortion of 0.002–0.003 Å, which is beyond the accuracy that the current DESI data can achieve. We refine the wavelength calibration using sky lines for a small fraction of the galaxies, but this does not change our main results. We further probe the spatial variation of α in small redshift ranges, and do not find obvious, large-scale structures in the spatial distribution of Δα/α. As DESI is ongoing, we will include more galaxies, and by improving the wavelength calibration, we expect to obtain a better constraint that is comparable to the strongest current constraint.

Keywords: Interdisciplinary astronomy, Galaxy spectroscopy, Emission line galaxies
Radiation MHD Simulations of Soft X-Ray Emitting Regions in Changing Look AGN. Strong soft X-ray emission called soft X-ray excess is often observed in luminous active galactic nuclei (AGN). It has been suggested that the soft X-rays are emitted from a warm (T = 106 ∼ 107 K) region that is optically thick for the Thomson scattering (warm Comptonization region). Motivated by the recent observations that soft X-ray excess appears in changing look AGN (CLAGN) during the state transition from a dim state without broad emission lines to a bright state with broad emission lines, we performed global three-dimensional radiation magnetohydrodynamic simulations, assuming that the mass accretion rate increases and becomes around 10% of the Eddington accretion rate. The simulation successfully reproduces a warm, Thomson-thick region outside the hot radiatively inefficient accretion flow near the black hole. The warm region is formed by efficient radiative cooling due to inverse Compton scattering. The calculated luminosity 0.01‑0.08 L Edd is consistent with the luminosity of CLAGN. We also found that the warm Comptonization region is well described by the steady model of magnetized disks supported by azimuthal magnetic fields. When the antiparallel azimuthal magnetic fields supporting the radiatively cooled region reconnect around the equatorial plane of the disk, the temperature of the region becomes higher by releasing the magnetic energy transported to the region.

Keywords: Accretion, Active galactic nuclei, Radiative magnetohydrodynamics
The Dynamics and Gravitational-wave Signal of a Binary Flying Closely by a Kerr Supermassive Black Hole. Recent astrophysical models predict that stellar-mass binary black holes (BBHs) could form and coalesce within a few gravitational radii of a supermassive black hole (SMBH). Detecting the gravitational waves (GWs) from such systems requires numerical tools that can track the dynamics of the binaries while capturing all the essential relativistic effects. This work develops upon our earlier study of a BBH moving along a circular orbit in the equatorial plane of a Kerr SMBH. Here we modify the numerical method to simulate a BBH falling toward the SMBH along a parabolic orbit of arbitrary inclination with respect to the equator. By tracking the evolution in a frame freely falling alongside the binary, we find that the eccentricity of the BBH is more easily excited than it is in the previous equatorial case, and that the cause is the asymmetry of the tidal tensor imposed on the binary when the binary moves out of the equatorial plane. Since the eccentricity reaches maximum around the same time as the BBH becomes the closest to the SMBH, multiband GW bursts could be produced that are simultaneously detectable by space- and ground-based detectors. We show that the effective spin parameters of such GW events also undergo significant variation due to the rapid reorientation of the inner BBHs during their interaction with SMBHs. These results demonstrate the richness of three-body dynamics in the region of strong gravity, and highlight the necessity of building new numerical tools to simulate such systems.

Keywords: Gravitational wave sources, Supermassive black holes, Stellar mass black holes, Astrophysical black holes
Frozen-field Modeling of Coronal Condensations with MPI-AMRVAC. I. Demonstration in Two-dimensional Models. Large-scale coronal plasma evolutions can be adequately described by magnetohydrodynamics (MHD) equations. However, full multidimensional MHD simulations require substantial computational resources. Given the low plasma β in the solar corona, in many coronal studies, it suffices to approximate the magnetic field to remain topologically fixed and effectively conduct one-dimensional (1D) hydrodynamic (HD) simulations instead. This approach is often employed in studies of coronal loops and their liability to form condensations related to thermal instability. While 1D HD simulations along given and fixed field line shapes are convenient and fast, they are difficult to directly compare with multidimensional phenomena. Therefore, it is more convenient to solve volume-filling, multidimensional versions of the MHD equations where we freeze the magnetic field, transforming it into frozen-field HD (ffHD) equations for simulation. We have incorporated this ffHD module into our open-source MPI-AMRVAC code and tested it using a two-dimensional (2D) evaporation–condensation model to study prominence formation due to radiative losses. The 2D ffHD results are compared with those from actual 2D MHD and pseudo-2D HD simulations, analyzing the differences and their causes. Pseudo-2D studies account for the known flux tube expansion effects. Overall, the performance of 2D ffHD is close to that of 2D MHD and pseudo-2D HD. The 2D tests conducted in this paper will be extended in follow-up studies to 3D simulations based on analytical or observational approaches.

Keywords: Solar atmosphere, Solar physics, Solar prominences, Magnetohydrodynamical simulations
Analysis of Neutron Star f-mode Oscillations in General Relativity with Spectral Representation of Nuclear Equations of State. We study quasi-normal f-mode oscillations in neutron star (NS) interiors within a linearized general relativistic formalism. We utilize approximately 9000 nuclear equations of state (EOSs) using spectral representation techniques, incorporating constraints on nuclear saturation properties, chiral effective field theory for pure neutron matter, and perturbative quantum chromodynamics for densities pertinent to NS cores. The median values of the f-mode frequency, ν  f  (damping time, τ  f ) for NSs with masses ranging from 1.4 to 2.0 M ⊙ lie between 1.80 and 2.20 kHz (0.13–0.22 s) for our entire EOS set. Our study reveals a weak correlation between f-mode frequencies and individual nuclear saturation properties, prompting the necessity for more intricate methodologies to unveil multiparameter relationships. We observe a robust linear relationship between the radii and f-mode frequencies for different NS masses. Leveraging this correlation alongside NICER observations of PSR J0740+6620 and PSR J0030+0451, we establish constraints that exhibit partial and minimal overlap for observational data from Riley et al. and Miller et al., respectively, with our nucleonic EOS data set. Moreover, NICER data align closely with the radius and frequency values for a few hadron–quark hybrid EOS models. This indicates the need to consider additional exotic particles such as deconfined quarks at suprasaturation densities. We conclude that future observations of the radius or f-mode frequency for more than one NS mass, particularly at the extremes of the viable NS mass scale, would either rule out nucleon-only EOSs or provide definitive evidence in its favor.

Keywords: Neutron stars, Quasinormal modes
The AGORA High-resolution Galaxy Simulations Comparison Project. IV. Halo and Galaxy Mass Assembly in a Cosmological Zoom-in Simulation at z ≤ 2. In this fourth paper from the AGORA Collaboration, we study the evolution down to redshift z = 2 and below of a set of cosmological zoom-in simulations of a Milky Way mass galaxy by eight of the leading hydrodynamic simulation codes. We also compare this CosmoRun suite of simulations with dark matter-only simulations by the same eight codes. We analyze general properties of the halo and galaxy at z = 4 and 3, and before the last major merger, focusing on the formation of well-defined rotationally supported disks, the mass─metallicity relation, the specific star formation rate, the gas metallicity gradients, and the nonaxisymmetric structures in the stellar disks. Codes generally converge well to the stellar-to-halo mass ratios predicted by semianalytic models at z ∼ 2. We see that almost all the hydro codes develop rotationally supported structures at low redshifts. Most agree within 0.5 dex with the observed mass─metallicity relation at high and intermediate redshifts, and reproduce the gas metallicity gradients obtained from analytical models and low-redshift observations. We confirm that the intercode differences in the halo assembly history reported in the first paper of the collaboration also exist in CosmoRun, making the code-to-code comparison more difficult. We show that such differences are mainly due to variations in code-dependent parameters that control the time stepping strategy of the gravity solver. We find that variations in the early stellar feedback can also result in differences in the timing of the low-redshift mergers. All the simulation data down to z = 2 and the auxiliary data will be made publicly available.

Keywords: Hydrodynamical simulations, Galaxy formation, Galaxy evolution
Atmospheric Retrievals of the Phase-resolved Spectra of Irradiated Brown Dwarfs WD-0137B and EPIC-2122B. We present an atmospheric retrieval analysis of Hubble Space Telescope/Wide Field Camera 3/G141 spectroscopic phase curve observations of two brown dwarfs, WD-0137B and EPIC-2122B, in ultrashort period orbits around white dwarf hosts. These systems are analogous to hot and ultra-hot Jupiter systems, enabling a unique and high-precision comparison to exoplanet systems. We use the PHOENIX Exoplanet Retrieval Algorithm retrieval suite to test various analysis setups, including joint-phase retrievals, multiple temperature structures, and nonuniform abundances. We find that WD-0137B has a dayside that closely resembles that of other ultra-hot Jupiters with inverted temperature structures and H‑ opacity, but quickly transitions to a mostly noninverted temperature structure on the nightside. Meanwhile, EPIC-2122B's atmosphere remains inverted at all constrained longitudes, with dominant H‑ opacity. Retrievals with multiple temperature profiles and nonuniform vertical abundances were generally not statistically justified for this data set, but retrievals with dayside-dilution factors were found to be justified. Retrieving all phases simultaneously with a linear combination of a dayside and nightside atmosphere was found to be an adequate representation of the entire phase curve once a longitudinal temperature gradient free parameter was included in the retrieval. Comparing to global circulation models, we attribute behavior in the 1D retrievals to the inclined viewing geometry of the systems, which results in always-visible irradiated and inverted portions of the atmosphere contaminating spectra measured from the nightside hemisphere. This study sheds light on the similarities between these irradiated brown dwarf systems and hot and ultra-hot Jupiters, but also their unique differences, including the influence of the inclined viewing geometry.

Keywords: Exoplanet atmospheres, Brown dwarfs, Infrared spectroscopy, Stellar atmospheres
Stellar Abundances at the Center of Early-type Galaxies with Fine Structure. Our understanding of early-type galaxies (ETGs) has grown in the past decade with the advance of full-spectrum fitting techniques used to infer the properties of the stellar populations that make up the galaxy. We present ages, central velocity dispersions, and abundance ratios relative to Fe of C, N, O, Mg, Si, Ca, Ti, Cr, Mn, Co, Ni, Cu, Sr, Ba, and Eu, derived using full-spectrum fitting techniques for three ETGs, NGC 2865, NGC 3818, and NGC 4915. Each of these three galaxies were selected because they have optical, disturbed structures (fine structure) that are linked to major merger events that occurred 1, 7, and 6 Gyr ago, respectively. Two of the ETGs, NGC 3818 and NGC 4915, show chemical signatures similar to ETGs without fine structure, which is consistent with a gas-poor merger of elliptical galaxies in which substantial star formation is not expected. For NGC 2865, we find a statistically higher abundance of Ca (an α element) and Cr and Mn (Fe-peak elements). We show that for NGC 2865, a simple gas-rich merger scenario fails to explain the larger abundance ratios compared to ETGs without fine structure. These three ETGs with fine structure exhibit a range of abundances, suggesting ETGs with fine structure can form via multiple pathways and types of galaxy mergers.

Keywords: Chemical enrichment, Chemical abundances, Early-type galaxies, Spectroscopy
Role of Polycyclic Aromatic Hydrocarbons with Edge Defects in Explaining Astronomical Infrared Emission Observations. A systematic study was performed on the spectral properties of polycyclic aromatic hydrocarbons (PAHs) with edge defects using harmonic density functional theory calculations. Their potential astronomical relevance was assessed through direct comparison with NIRSpec and MIRI-MRS spectra of the atomic photodissociation region of the Orion Bar from the JWST Early Release Science PDRs4All program. It is found that the astronomical 6.2 μm PAH emission band, including its blue side, is well reproduced by PAHs with edge defects, when taking into account the effects of polarization in the computations, and without a need for PAHs that contain nitrogen. Small neutral PAHs with edge defects explain the blue wing of the 3.3 μm band. A low number of edge defects is required to reproduce the 8.6 and 11.2 μm band profiles, while the 11.0 + 11.2/12.7 μm band intensity ratio is a measure for the number of edge defects. A blind database fit to the Orion Bar spectrum reproduces the 6–15 μm region with an error of 9.9% and shows a clear delineation of charge, with the 6–10 μm PAH bands being carried by PAH cations and the 10–15 μm region by predominantly neutral PAHs. The contribution of anions is negligible. Armchair PAHs fit the 12.7 μm band, simultaneously producing a very weak broad emission feature centered at 3.225 μm. Zigzag PAHs fit the 11.2 μm band. It is concluded that PAHs with a low number of edge defects, in addition to armchair and zigzag PAHs, all contribute to the observed interstellar infrared emission.

Keywords: Infrared astronomy, Molecular spectroscopy