Sazuna/UAT_keywords huggingface dataset:
Varying Activity and the Burst Properties of FRB 20240114A Probed with GMRT Down to 300 MHz. Repeating fast radio bursts (FRBs) can exhibit a wide range of burst repetition rates, from none to hundreds of bursts per hour. Here we report the detection and characteristics of 60 bursts from the recently discovered FRB 20240114A, observed with the upgraded Giant Metrewave Radio Telescope in the frequency ranges 300–500 MHz and 550–750 MHz. The majority of the bursts show narrow emission bandwidth with Δν/ν ∼ 10%. All of the bursts we detect are faint (&lt;10 Jy ms) and thus probe the lower end of the energy distribution. We determine the rate function for FRB 20240114A at 400 MHz and downward drift rates at 400 and 650 MHz, and we discuss our measurements in the context of the repeating FRB population. We observe sudden variations in the burst activity of FRB 20240114A over time. From our data and the publicly available information on other observations of FRB 20240114A so far, there is an indication that FRB 20240114A potentially exhibits chromaticity in its burst activity. While the burst properties of FRB 20240114A are similar to other repeating FRBs, the frequency-dependent activity, if established, could provide crucial clues to the origin of repeating FRBs. We also place the most stringent 5σ upper limits of 600 and 89 μJy on any persistent radio source (PRS) associated with FRB 20240114A at 400 and 650 MHz, respectively, and compare these with the luminosity of the known PRSs associated with FRB 121102A and FRB 190520B.

Keywords: Radio transient sources
Unveiling the Emission Mechanisms of Blazar PKS 1510-089. I. Multiwavelength Variability. The flat spectrum radio quasar PKS 1510-089 is one of the most active blazars in γ-rays, exhibiting phases of very high activity. This study investigates its variability over a decade across a wide range of wavelengths, from radio to γ-rays. Utilizing the nonthermal dominance parameter, we analyze the Hβ, Hγ, and λ5100 Å continuum light curves to discern the primary source of continuum emission, either from the accretion disk or the jet, during different activity phases. Our findings underscore the dominance of jet emission in the continuum during flare-like events. We observed an approximately 80 day delay between the Hβ and continuum emissions, which we attribute to the spatial separation between the optical emission zone and the broad-line region. Near-zero delays between optical and near-infrared emissions suggest that the emitting regions within the jet are cospatial. Synchrotron self-Compton was identified as the primary mechanism for γ-ray emission during flares, supported by the minimal delay observed between optical/near-infrared emissions and γ-rays. Additionally, we found a delay of about 60 days between the leading optical/near-infrared emissions and X-rays, indicating that inverse Compton scattering within the jet predominantly drives X-ray emission. However, distinguishing between synchrotron self-Compton and external inverse Compton mechanism was not feasible. Shifts in the spectral index across the 15–230 GHz range corresponded with ejections from the radio core, suggesting changes in the physical conditions of the jet.

Keywords: Supermassive black holes, Flat-spectrum radio quasars, Active galaxies, Galaxy jets, Emission line galaxies, Gamma-rays
Exploring the Diversity of Faint Satellites in the M81 Group. In the last decade, we have been able to probe further down the galaxy luminosity function than ever before and expand into the regime of ultra-faint dwarfs (UFDs), which are some of the best probes we have of small-scale cosmology and galaxy formation. Digital sky surveys have enabled the discovery and study of these incredibly low-mass, highly dark-matter-dominated systems around the Local Group, but it is critical that we expand the satellite census further out to understand if Milky Way and M31 satellites are representative of dwarf populations in the local Universe. Using data from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS), we present updated characterization of four satellite systems in the M81 group. These systems—D1005+68, D1006+69, DWJ0954+6821, and D1009+68—were previously discovered using ground-based Subaru Hyper Suprime-Cam data as overdensities in M81's halo, and are now confirmed with HST/ACS by this work. These are all faint (M  V  ≥ ‑7.9) and consistent with old (∼13 Gyr), metal-poor ([M/H] &lt; ‑1.5) populations. Each system possesses relatively unusual features—including one of the most concentrated satellite galaxies with a Sérsic index of n ∼ 5, one of the most elliptical galaxies outside the Local Group with an ϵ ∼ 0.6, and one of the most compact galaxies for its magnitude. Two of the satellites have very low surface brightness, lower than most known galaxies in this absolute magnitude range. This work previews the scientific promise of the upcoming Rubin Observatory and Roman Telescope for illuminating the diversity of UFDs in the Local Volume and beyond.

Keywords: RGB photometry, Hubble Space Telescope, Dwarf galaxies, HST photometry, Galaxies, Low surface brightness galaxies
"SNe Ia Twins for Life": Toward a Precise Determination of H <SUB>0</SUB>. Here we present an approach to the measurement of extragalactic distances using twin SNe Ia, taken from the early down to the nebular phase. The approach is purely empirical, although we can give a theoretical background on why the method is reliable. By studying those twins in galaxies where peculiar velocities are relatively unimportant, we can tackle the H 0 tension problem. Here we apply the method to the determination of the distances to NGC 7250 and NGC 2525, who hosted, respectively, SN 2013dy and SN 2018gv, twins of two different SNe Ia prototypes: SN 2013aa/SN 2017cbv and SN 2011fe. From the study of the SN 2013aa and SN 2017cbv twin pair, by comparing it with SN 2011fe and applying the difference between the SN 2013aa/2017cbv and the SN 2011fe class, we also find a good estimate of the distance to NGC 5643. We have just started to measure distances with the method for the samples in W.L Freedman et al. and A. G. Riess et al. There are differences in measured distances to the same galaxy using Cepheids or TRGBs. In this context of discrepancy, the "twins for life" method is very competitive because it can provide distance estimates with a modulus error of σ  μ  = 0.04 mag. Our findings called for a revision of the distances measured with Cepheids in A. G. Riess et al. (2022). NGC 7250 and NGC 2525 needed better measurements with Cepheids. We have noticed that the Cepheids-based distance obtained with the JWST in A. G. Riess et al. (2024a) for NGC 5643 is in good agreement with what we find, unlike their previous estimate in A. G. Riess et al. (2022). The Hubble tension can arise from the way in which the local SNe Ia sample is linked to the SNe Ia Hubble flow sample. A good calibration of SNe Ia in the local sample is needed and we have started to gather it. We also expect to apply the "twin" SNe Ia comparison from the local sample to that in galaxies with z &gt;0.02–0.03 well into the Hubble flow to obtain a reliable value for H 0. Those distant SNe Ia can be observed with the ELT or the JWST.

Keywords: Hubble constant, Galaxy distances, Type Ia supernovae
Synchrotron Break Frequencies of Mildly to Highly Relativistic Outflows Observed Off-axis. We consider the synchrotron spectrum produced by mildly to highly relativistic collisionless shocks. Simple analytic formulae are derived for the break frequencies (peak frequency, self-absorption frequency, synchrotron, and inverse Compton cooling frequencies) of the emission produced by postshock plasma elements propagating at an angle θe relative to the observer's line of sight. These formulae reproduce well the results of earlier exact analytic calculations valid for ultrarelativistic shocks and also hold for γ &lt; 10 and for "off-axis" propagation (deviating from the ultrarelativistic results by approximately 1 order of magnitude). Our results will improve parameter estimation accuracy from future observations of synchrotron emission produced by collisionless shocks driven by the relativistic ejected material from compact object mergers and jetted tidal disruption events. The improved accuracy for mildly relativistic velocities is essential since most events will be observed off-axis, with γ &lt; 10 outflows dominating the synchrotron emission (due to relativistic beaming). For GW170817, our results imply that (i) the Lorentz factor of the plasma emitting the observed radiation is bounded by 2.6 &lt; γ at t ∼ 10 days and by γ &lt; 12 at t &gt; 16 days, (ii) the interstellar medium (ISM) density, n, and the fraction of internal energy density held by magnetic fields, ɛB, are bounded by n · ɛB ≲ 3 × 10‑7 cm‑3. In future merger events in higher-density ISM, the peak and cooling frequencies may be identified in the radio and X-ray bands; consequently, γ, n · ɛB could be measured as opposed to the case of GW170817, where these frequencies are out of the observable range.

Keywords: Neutron stars, Gravitational wave sources, X-ray transient sources, Gamma-ray transient sources, Relativistic fluid dynamics, Radio transient sources
Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. I. Physical Origin of the Band Function and Application to GRBs 090926A, 131108A, and 160509A. The radiation physics of gamma-ray bursts (GRBs) remains an open question. Based on the simulation analysis and recent observations, it was proposed that GRB jets are composed of a narrow ultrarelativistic core surrounded by a wide subrelativistic cocoon. We show that emission from the synchrotron radiations and the synchrotron self-Compton (SSC) process of shear-accelerated electrons in the mixed jet-cocoon (MJC) region and internal-shock-accelerated electrons in the jet core is potentially explained the spectral characteristics of the prompt gamma rays. Assuming an exponential-decay velocity profile, the shear flow in the MJC region can accelerate electrons up to   for injected electrons with γ e,inject = 3 × 102 if its magnetic field strength ( ) is 100 G and its inner-edge velocity ( ) is 0.9 c. The cooling of these electrons is dominated by the SSC process, and the emission flux peaks at the keV band. In addition, the energy flux of synchrotron radiations of internal-shock-accelerated electrons (γ  e  = 104 ∼ 105) peaks at around the keV‑MeV band, assuming a bulk Lorentz factor of 300, a magnetic field strength of ∼106 G for the jet core. Adding the flux from both the jet core and the MJC region, the total spectral energy distribution illustrates similar characteristics as the broadband observations of GRBs. The bimodal and Band cut spectra observed in GRBs 090926A, 131108A, and 160509A can be well fit with our model. The derived   varies from 54 G to 450 G and   c.

Keywords: Gamma-ray bursts, Non-thermal radiation sources
Emergence of the Galaxy Morphology–Star Formation Activity–Clustercentric Radius Relations in Galaxy Clusters. We investigate when and how the relations of galaxy morphology and star-forming activity with clustercentric radius become evident in galaxy clusters. We identify 162 galaxy clusters with total mass   at z = 0.625 in the Horizon Run 5 cosmological hydrodynamical simulation and study how the properties of the galaxies with stellar mass M * &gt; 5 × 109 M ⊙ near the cluster main progenitors have evolved in the past. Galaxies are classified into disk, spheroid, and irregular morphological types according to the asymmetry and Sérsic index of their stellar mass distribution. We also classify galaxies into active and passive ones depending on their specific star formation rate. We find that the morphology–clustercentric radius relation (MRR) emerges at z ≃ 1.8 as the fraction of spheroidal types exceeds 50% in the central region (d ≲ 0.1R 200). Galaxies outside the central region remain disk-dominated. Numerous encounters between galaxies in the central region seem to be responsible for the morphology transformation from disks to spheroids. We also find that the star formation activity–clustercentric radius relation emerges at an epoch different from that of MRR. At z ≃ 0.8, passive galaxies start to dominate the intermediate radius region (0.1 ≲ d/R 200 ≲ 0.3), and this "quenching region" grows inward and outward thereafter. The region dominated by early-type galaxies (spheroids and passive disks) first appears at the central region at z ≃ 1.8, expands rapidly to larger radii as the population of passive disks grows in the intermediate radii, and clusters are dominated by early types after z ≃ 0.8.

Keywords: Galaxy clusters, Galaxy interactions, Galaxy evolution
High-precision Galaxy Clustering Predictions from Small-volume Hydrodynamical Simulations via Control Variates. Cosmological simulations of galaxy formation are an invaluable tool for understanding galaxy formation and its impact on cosmological parameter inference from large-scale structures. However, their high computational cost is a significant obstacle for running simulations that probe cosmological volumes comparable to those analyzed by contemporary large-scale structure experiments. In this work, we explore the possibility of obtaining high-precision galaxy clustering predictions from small-volume hydrodynamical simulations such as MillenniumTNG and FLAMINGO via control variates. In this approach, the hydrodynamical full-physics simulation is paired with a matched low-resolution gravity-only simulation. By learning the galaxy–halo connection from the hydrodynamical simulation and applying it to the gravity-only counterpart, one obtains a galaxy population that closely mimics the one in the more expensive simulation. One can then construct an estimator of galaxy clustering that combines the clustering amplitudes in the small-volume hydrodynamical and gravity-only simulations with clustering amplitudes in a large-volume gravity-only simulation. Depending on the galaxy sample, clustering statistic, and scale, this galaxy clustering estimator can have an effective volume of up to around 100 times the volume of the original hydrodynamical simulation in the nonlinear regime. With this approach, we can construct galaxy clustering predictions from existing simulations that are precise enough for mock analyses of next-generation large-scale structure surveys such as the Dark Energy Spectroscopic Instrument and the Legacy Survey of Space and Time.

Keywords: Hydrodynamical simulations, Galaxy formation, Galaxy dark matter halos, Large-scale structure of the universe, Astrostatistics
Visual Orbits of Wolf–Rayet Stars. II. The Orbit of the Nitrogen-rich Wolf–Rayet Binary WR 138 Measured with the CHARA Array. Classical Wolf–Rayet (WR) stars are descendants of massive OB-type stars that have lost their hydrogen-rich envelopes and are in the final stages of stellar evolution, possibly exploding as Type Ib/c supernovae. It is understood that the mechanisms driving this mass loss are either strong stellar winds and or binary interactions, so intense studies of these binaries including their evolution can tell us about the importance of the two pathways in WR formation. WR 138 (HD 193077) has a period of just over 4 yr and was previously reported to be resolved through interferometry. We report on new interferometric data combined with spectroscopic radial velocities in order to provide a three-dimensional orbit of the system. The precision on our parameters tend to be about an order of magnitude better than previous spectroscopic techniques. These measurements provide masses of the stars, namely, M WR = 13.93 ± 1.49 M ⊙ and M O = 26.28 ± 1.71 M ⊙. The derived orbital parallax agrees with the parallax from Gaia, namely, with a distance of 2.13 kpc. We compare the system's orbit to models from BPASS, showing that the system likely may have been formed with little interaction but could have formed through some binary interactions either following or at the start of a red supergiant phase but with the most likely scenario occurring as the red supergiant phase starts for a ∼40 M ⊙ star.

Keywords: Wolf-Rayet stars, Interferometric binary stars, WN stars, Long baseline interferometry
The Alignment of High-resolution Solar Prominence Images Observed by the New Vacuum Solar Telescope. High spatial resolution observation of solar prominence is an important observation subject of the New Vacuum Solar Telescope (NVST). While the current level of observation and image reconstruction technologies for solar prominences are advanced, a significant challenge remains in achieving high-precision alignment among high-resolution prominence images observed at different times and different off-bands. Existing alignment approaches either become ineffective or yield low accuracy, and always require manual intervention during the alignment. These limitations are largely due to the stronger edge gradient and lower structural contrast of the prominence images compared with the solar surface ones. In response to this challenge, our study aims to develop an effective and robust algorithm for high-precision alignment of the prominence images. We thoroughly consider the unique structural characteristics of prominence images and the specific application conditions of various alignment algorithms. Consequently, we propose a comprehensive alignment method that incorporates the optical flow field of the solar surface, the gradient of the solar edge, and the cross-correlation within the solar prominence region. This method is designed to accurately determine the movement displacements among the prominence images. Our results demonstrate that this alignment method excels in both accuracy and robustness, making it well-suited for handling the diverse postures of solar prominence images captured by the NVST.

Keywords: Solar chromosphere, Solar prominences, Astronomy data reduction
Theoretical Diagnostics for Narrow-line Regions of Active Galactic Nuclei. Gas metallicity, ionization parameter, and gas pressure can affect the observed ratios of specific strong emission lines within galaxies. While the theoretical strong lines diagnostics for gas metallicity, ionization parameters, and gas pressure in star-forming regions are well-established, theoretical diagnostics for active galactic nuclei (AGNs) narrow-line regions are still lacking. In P. Zhu et al., we presented a new AGN model that provides the best predictions for observations spanning the UV, optical, and infrared wavelengths. This paper presents a suite of theoretical diagnostics for the gas metallicity, ionization parameter, gas pressure, and the peak energy in AGN ionizing radiation field E peak for AGN narrow-line regions spanning the UV and optical wavelengths. We investigate the model dependency on the ionization parameter, gas pressure, E peak, and the nitrogen scaling relation and make recommendations on metallicity diagnostics that are most robust against these parameters. We test our new AGN metallicity diagnostics using optical galaxy spectra from Sloan Digital Sky Survey DR16. These tests show that the metallicities measured from different diagnostics in this paper are consistent within ∼0.3 dex. We compare consistent H II and AGN diagnostics and demonstrate that H II and AGN diagnostics should not be used interchangeably. With a wide wavelength coverage, we anticipate that these AGN diagnostics will enable new metallicity studies of galaxies dominated by AGN.

Keywords: Active galactic nuclei, Galaxy abundances, Metallicity
Photochemical Hazes in Exoplanetary Skies with Diamonds: Microphysical Modeling of Haze Composition Evolution via Chemical Vapor Deposition. Observational efforts in the last decade suggest the prevalence of photochemical hazes in exoplanetary atmospheres. Recent JWST observations raise growing evidence that exoplanetary hazes tend to have reflective compositions, unlike the conventionally assumed haze analogs, such as tholin and soot. In this study, I propose a novel hypothesis: diamond formation through chemical vapor deposition (CVD) may be happening in exoplanetary atmospheres. Using an aerosol microphysical model combined with the theory of CVD diamond and soot formation established in the industry community, I study how the haze composition evolves in exoplanetary atmospheres for various planetary equilibrium temperatures, atmospheric metallicity, and C/O ratio. I find that CVD diamond growth dominates over soot growth in a wide range of planetary parameters. Diamond haze formation is most efficient at T eq ∼ 1000 K and low atmospheric metallicity ([M/H] ≤ 2.0), while soot could be the main haze component only if the atmosphere is hot (T eq ≳ 1200 K) and carbon rich (C/O &gt; 1). I also compute transmission, emission, and reflected light spectra, thereby suggesting possible observational signatures of diamond hazes, including the 3.53 μm feature of hydrogenated diamonds, anomalously faint thermal emission due to thermal scattering, and a drastic increase in geometric albedo. This study suggests that warm exoplanetary atmospheres may be favorable sites for forming CVD diamonds, which would be testable by future observations by JWST and Ariel as well as haze synthesis experiments under hot hydrogen-rich conditions.

Keywords: Exoplanets, Atmospheric clouds, Astrochemistry, Exoplanet atmospheres, Exoplanet atmospheric structure
An Empirical Framework Characterizing the Metallicity and Star-formation History Dependence of X-Ray Binary Population Formation and Emission in Galaxies. We present a new empirical framework modeling the metallicity and star formation history (SFH) dependence of X-ray luminous (L ≳ 1036 erg s‑1) point-source population X-ray luminosity functions (XLFs) in normal galaxies. We expect that the X-ray point-source populations are dominated by X-ray binaries (XRBs), with contributions from supernova remnants near the low luminosity end of our observations. Our framework is calibrated using the collective statistical power of 3731 X-ray detected point sources within 88 Chandra-observed galaxies at D ≲ 40 Mpc that span broad ranges of metallicity (Z ≈ 0.03–2 Z ⊙), SFH, and morphology (dwarf irregulars, late types, and early types). Our best-fitting models indicate that the XLF normalization per unit stellar mass declines by ≈2–3 dex from 10 Myr to 10 Gyr, with a slower age decline for low-metallicity populations. The shape of the XLF for luminous X-ray sources (L ≳ 1038 erg s‑1) significantly steepens with increasing age and metallicity, while the lower-luminosity XLF appears to flatten with increasing age. Integration of our models provides predictions for X-ray scaling relations that agree very well with past results presented in the literature, including, e.g., the L X–SFR–Z relation for high-mass XRBs in young stellar populations as well as the L X/M ⋆ ratio observed in early-type galaxies that harbor old populations of low-mass XRBs. The model framework and data sets presented in this paper further provide unique benchmarks that can be used for calibrating binary population synthesis models.

Keywords: X-ray astronomy, X-ray binary stars, Stellar evolutionary models, Star formation, Galaxy evolution, Spectral energy distribution