Sazuna/UAT_keywords huggingface dataset:
Morpho-kinematic Modeling of the Expanding Ejecta of the Extremely Slow Nova V1280 Scorpii. Knowledge of the morphology of nova ejecta is essential for fully understanding the physical processes involved in nova eruptions. We studied the 3D morphology of the expanding ejecta of the extremely slow nova V1280 Sco with a unique light curve. Synthetic line profile spectra were compared to the observed [O III] λλ4959, 5007 and [N II] λ5755 emission line profiles in order to find the best-fit morphology, inclination angle, and maximum expansion velocity of the ejected shell. We derive the best-fitting expansion velocity, inclination, and squeeze as ${V}_{\exp }={2100}_{-100}^{+100}$ km s-1, $i={80}_{-3}^{+1}$ deg, and ${squ}={1.0}_{-0.1}^{+0.0}$ using [O III] line profiles, and ${V}_{\exp }={1600}_{-100}^{+100}$ km s-1, $i={81}_{-4}^{+2}$ deg, and ${squ}={1.0}_{-0.1}^{+0.0}$ using the [N II] λ5755 line profile. A high inclination angle is consistent with the observational results showing multiple absorption lines originating from clumpy gases, which are produced in dense and slow equatorially focused outflows. Based on additional observational features such as optical flares near the maximum light and dust formation on V1280 Sco, a model of internal shock interaction between slow ejecta and fast wind proposed for the γ-ray emission detected in other novae seems to be applicable to this extremely slow and peculiar nova. Increasing the sample size of novae whose morphology is studied will be helpful in addressing long-standing mysteries in novae such as the dominant energy source to power the optical light at the maximum, optical flares near the maximum, clumpiness of the ejecta, and dust formation.

Keywords: High resolution spectroscopy, Slow novae, Novae, Stellar mass loss, Stellar winds, Stellar physics, Spectroscopy, Cataclysmic variable stars, Classical novae
In Search of Short Gamma-Ray Burst Optical Counterparts with the Zwicky Transient Facility. The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to ~40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020-2021. Bridging the large sky areas with small field-of-view optical telescopes in order to track the evolution of potential candidates, we look for the elusive SGRB afterglows and kilonovae (KNe) associated with these high-energy events. No counterpart has yet been found, even though more than 10 ground-based telescopes, part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network, have taken part in these efforts. The candidate selection procedure and the follow-up strategy have shown that ZTF is an efficient instrument for searching for poorly localized SGRBs, retrieving a reasonable number of candidates to follow up and showing promising capabilities as the community approaches the multi-messenger era. Based on the median limiting magnitude of ZTF, our searches would have been able to retrieve a GW170817-like event up to ~200 Mpc and SGRB afterglows to z = 0.16 or 0.4, depending on the assumed underlying energy model. Future ToOs will expand the horizon to z = 0.2 and 0.7, respectively.

Keywords: Gamma-ray bursts, Wide-field telescopes
Substructures in Protoplanetary Disks Imprinted by Compact Planetary Systems. The substructures observed in protoplanetary disks may be the signposts of embedded planets carving gaps or creating vortices. The inferred masses of these planets often fall in the Jovian regime despite their low abundance compared to lower-mass planets, partly because previous works often assume that a single substructure (a gap or vortex) is caused by a single planet. In this work, we study the possible imprints of compact systems composed of Neptune-like planets (~10-30 M ⊕) and show that long-standing vortices are a prevalent outcome when their interplanetary separation (Δa) falls below ~8 times H p-the average disk's scale height at the planet's locations. In simulations where a single planet is unable to produce long-lived vortices, two-planet systems can preserve them for at least 5000 orbits in two regimes: (i) fully shared density gaps with elongated vortices around the stable Lagrange points L 4 and L 5 for the most compact planet pairs (Δa ≲ 4.6 H p), and (ii) partially shared gaps for more widely spaced planets (Δa ~ 4.6-8 H p) forming vortices in a density ring between the planets through the Rossby wave instability. The latter case can produce vortices with a wide range of aspect ratios down to ~3 and can occur for planets captured into the 3:2 (2:1) mean-motion resonances for disks' aspects ratios of h ≳ 0.033 (h ≳ 0.057). We suggest that their long lifetimes are sustained by the interaction of spiral density waves launched by the neighboring planets. Overall, our results show that the distinguishing imprint of compact systems with Neptune-mass planets are long-lived vortices inside the density gaps, which in turn are shallower than single-planet gaps for a fixed gap width.

Keywords: Exoplanet dynamics, Hydrodynamical simulations, Exoplanet migration, Planetary-disk interactions, Protoplanetary disks, Exoplanet formation
Frequency Analysis of KIC 1573174: Shedding Light on the Nature of HADS Stars. We propose that KIC 1573174 is a quadruple-mode δ Scuti star with pulsation amplitudes between those of the high-amplitude Delta Scuti star group and average low-amplitude pulsators. The radial modes detected in this star provide a unique opportunity to exploit asteroseismic techniques up to their limits. Detailed frequency analysis is given for the light curve from the Kepler mission. The variation of the light curve is dominated by the strongest mode with a frequency of F0 = 7.3975 day-1, as shown by Fourier analysis of long cadence data (Q1-Q17, spanning 1460 days), indicating that the target is a δ Scuti star. The other three independent modes with F1 = 9.4397 day-1, F2 = 12.1225 day-1, and F3 = 14.3577 day-1, have ratios of P 1/P 0, P 2/P 0, and P 3/P 0 estimated as 0.783, 0.610, and 0.515, which indicate that KIC 1573174 is a quadruple-mode δ Scuti star. A different approach has been used to determine the O - C through the study of phase modulation. The change of period (1/P)dP/dt is obtained resulting in -1.14 × 10-6 yr-1 and -4.48 × 10-6 yr-1 for F0 and F1 respectively. Based on frequency parameters (i.e., F0, F1, F2, and F3), a series of theoretical models were conducted by employing the stellar evolution code MESA. The ratio of observed f 1/f 2 is larger than that of the model, which may be caused by the rotation of the star. We suggest high-resolution spectral observation is highly desired in the future to further constrain models.

Keywords: Asteroseismology, Delta Scuti variable stars, Stellar evolution
Chandra Follow-up Observations of Swift-BAT-selected AGNs II. We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z ≤ 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150 month catalog. We located soft (1-10 keV) X-ray counterparts to these BAT sources and joint fit their spectra with physically motivated models. The spectral analysis in the 1-150 keV energy band determined that all sources are obscured, with a line-of-sight column density N  H  ≥ 1022 cm-2 at a 90% confidence level. Four of these sources show significant obscuration with N  H  ≥ 1023 cm-2 and two additional sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs) with N  H  ≥ 1024 cm-2. These two sources, 2MASX J02051994-0233055 and IRAS 11058-1131, are the latest addition to the previous 3 CT-AGN candidates found using our strategy for soft X-ray follow-up of BAT sources. Here we present the results of our methodology so far, and analyze the effectiveness of applying different selection criteria to discover CT-AGN in the local Universe. Our selection criteria has an ~20% success rate of discovering heavily obscured AGN whose CT nature is confirmed by follow-up NuSTAR observations. This is much higher than the ~5% found in blind surveys.

Keywords: Seyfert galaxies, X-ray active galactic nuclei, Active galactic nuclei, High energy astrophysics
Stellar Halos from the The Dragonfly Edge-on Galaxies Survey. We present the primary results from the Dragonfly Edge-on Galaxies Survey, an exploration of the stellar halos of twelve nearby (d &lt; 25 Mpc) edge-on disk galaxies with the Dragonfly Telephoto Array. The edge-on orientation of these galaxies allows their stellar halos to be explored with minimal obscuration by or confusion with the much brighter disk light. Galaxies in the sample span a range of stellar masses from 109.68 to 1010.88 M ⊙. We confirm that the wide range of stellar halo mass fractions previously seen for Milky Way-mass galaxies is also found among less massive spiral galaxies. The scatter in stellar halo mass fraction is large, but we do find a significant positive correlation between stellar halo mass fraction and total stellar mass when the former is measured beyond five half-mass radii. Reasonably good agreement is found with predictions from cosmological hydrodynamical simulations, although observed stellar halo fractions appear to be somewhat lower than expected from these simulations.

Keywords: Galaxy stellar halos, Galaxy structure, Galaxy photometry, Spiral galaxies
NICER Monitoring of Supersoft X-Ray Sources. We monitored four supersoft sources-two persistent ones, CAL 83 and MR Vel, and the recent novae YZ Ret (Nova Ret 2020), and V1674 Her (Nova Her 2021)-with NICER. The two persistent supersoft X-ray sources (SSS) were observed with unvaried X-ray flux level and spectrum, respectively, 13 and 20 yr after the last observations. Short-period modulations of the SSS appear where the spectrum of the luminous central source was fully visible (in CAL 83 and V1674 Her) and were absent in YZ Ret and MR Vel, in which the flux originated in photoionized or shocked plasma, while the white dwarf (WD) was not observable. We thus suggest that the pulsations occur on, or very close to, the WD surface. The pulsations of CAL 83 were almost unvaried after 15 yr, including an irregular drift of the ≃67 s period by 2.1 s. Simulations, including previous XMM-Newton data, indicate actual variations in period length within hours, rather than an artifact of the variable amplitude of the pulsations. Large amplitude pulsations with a period of 501.53 ± 0.30 s were always detected in V1674 Her, as long as the SSS was observable. This period seems to be due to rotation of a highly magnetized WD. We cannot confirm the maximum effective temperature of (≃145,000 K) previously inferred for this nova, and discuss the difficulty in interpreting its spectrum. The WD appears to present two surface zones, one of which does not emit SSS flux.

Keywords: Novae
Analytic Approximations for the Velocity Suppression of Dark Matter Capture. Compact astrophysical objects have been considered in the literature as dark matter (DM) probes, via the observational effects of annihilating captured DM. In this paper we investigate the role of stellar velocity on multiscatter-capture rates and find that the capture rates of DM by a star moving with respect to the DM halo rest frame are suppressed by a predictable amount. We develop and validate an analytical expression for the capture rate suppression factor. This suppression factor can be used to directly reevaluate projected bounds on the DM-nucleon cross section, for any given stellar velocity, as we explicitly show using Population III stars as DM probes. These objects (Population III stars) are particularly interesting candidates, since they form at high redshifts, in very high DM-density environments. We find that previous results, obtained under the assumption of a star at rest with respect to the DM rest frame, are essentially unchanged when considering the possible orbital velocities for those central stars.

Keywords: Dark matter
The 30 Doradus Molecular Cloud at 0.4 pc Resolution with the Atacama Large Millimeter/submillimeter Array: Physical Properties and the Boundedness of CO-emitting Structures. We present results of a wide-field (approximately 60 × 90 pc) Atacama Large Millimeter/submillimeter Array mosaic of CO(2-1) and 13CO(2-1) emission from the molecular cloud associated with the 30 Doradus star-forming region in the Large Magellanic Cloud (LMC). Three main emission complexes, including two forming a bow-tie-shaped structure extending northeast and southwest from the central R136 cluster, are resolved into complex filamentary networks. Consistent with previous studies, we find that the central region of the cloud has higher line widths at a fixed size relative to the rest of the molecular cloud and to other LMC clouds, indicating an enhanced level of turbulent motions. However, there is no clear trend in gravitational boundedness (as measured by the virial parameter) with distance from R136. Structures observed in 13CO are spatially coincident with filaments and are close to a state of virial equilibrium. In contrast, 12CO structures vary greatly in virialization, with low CO surface brightness structures outside of the main filamentary network being predominantly unbound. The low surface brightness structures constitute ~10% of the measured CO luminosity; they may be shredded remnants of previously star-forming gas clumps, or alternatively the CO-emitting parts of more massive, CO-dark structures.

Keywords: Millimeter astronomy, Star forming regions, Giant molecular clouds, Interstellar medium, Magellanic Clouds
Circular Polarization Observations of Type II Solar Radio Bursts and the Coronal Magnetic Field. It is well known that magnetic field strength (B) in the solar corona can be calculated using the Alfvén Mach number (M  A ) and Alfvén speed (v  A ) of the magnetohydrodynamic shock waves associated with coronal type II radio bursts. We show that observations of weak circularly polarized emission associated with the harmonic component of the type II bursts provide independent and consistent estimates of B. For the coronal type II burst observed on 2021 October 9, we obtained B ≈1.5 G and ≈1.9 G at a heliocentric distance (r) of ≈1.8 R ⊙, using the above two techniques, respectively.

Keywords: The Sun, Solar radio emission, Solar magnetic fields, Solar coronal mass ejections, Solar corona
The <SUP>26</SUP>Al Production of the ν <SUB> e </SUB>-process in the Explosion of Massive Stars. The core collapses of massive stars at the ends of their lives will produce powerful streams of neutrinos, which provide an important contribution to the 26Al yield during the explosion stage. In this work, the contribution of the process ${}^{26}\mathrm{Mg}{({\nu }_{e},{e}^{-})}^{26}\mathrm{Al}$ to the radioactive 26Al in the Milky Way is studied based on a simple model. By combining the calculation of the neutrino-nucleus cross section and some hypotheses about core-collapse supernova explosions, the ratio of 26Al and 26Mg of the ν  e -process is estimated. An analytical relationship between the 26Mg yield and the initial mass and metallicity of massive stars is then obtained, making it easy to estimate the 26Mg and 26Al yields analytically. Due to the simplicity of the model, we can move away from complex calculations and into a careful study of the effects of some important factors, such as the radius of the O/Ne shell, the shock velocity, the neutrino spectrum, the Galactic mass and metallicity distribution, and so on. The uncertainties of the 26Al yield contributed from these factors are discussed in detail. This study will facilitate an intuitive understanding of the buried implicit assumptions in previous studies.

Keywords: Galaxy chemical evolution, Supernova neutrinos, Gamma-ray astronomy, Core-collapse supernovae
Improving Detection of Gravitational-wave Microlensing Using Repeated Signals Induced by Strong Lensing. Microlensing imprints by typical stellar-mass lenses on gravitational waves are challenging to identify in the LIGO-Virgo frequency band because such effects are weak. However, stellar-mass lenses are generally embedded in lens galaxies such that strong lensing accompanies microlensing. Therefore, events that are strongly lensed in addition to being microlensed may significantly improve the inference of the latter. We present a proof-of-principle demonstration of how one can use parameter estimation results from one strongly lensed signal to enhance the inference of the microlensing effects of the other signal with the Bayesian inference method currently used in gravitational-wave astronomy. We expect this to significantly enhance our future ability to detect the weak imprints from stellar-mass objects on gravitational-wave signals from colliding compact objects.

Keywords: Bayesian statistics, Strong gravitational lensing, Gravitational wave astronomy, Gravitational lensing, Gravitational waves, Gravitational microlensing, Astronomical methods
Testing Horndeski Gravity from EHT Observational Results for Rotating Black Holes. The Event Horizon Telescope (EHT) collaboration recently unveiled the first image of the supermassive black hole M87*, which exhibited a ring of angular diameter θ  d  = 42 ± 3 μas, a circularity deviation of ΔC ≤ 0.1, and also inferred a black hole mass of M = (6.5 ± 0.7) × 109 M ⊙. This provides a new window onto tests of theories of gravity in the strong-field regime, including probes of violations of the no-hair theorem. It is widely believed that the Kerr metric describes astrophysical black holes, as encapsulated in the critical but untested no-hair theorem. Modeling Horndeski gravity black holes-with an additional hair parameter h besides the mass M and spin a of the Kerr black hole-as the supermassive black hole M87*, we observe that to be a viable astrophysical black hole candidate, the EHT result constrains the (a, h) parameter space. However, a systematic bias analysis indicates that rotating Horndeski black hole shadows may or may not capture Kerr black hole shadows, depending on the parameter values; the latter is the case over a substantial part of the constrained parameter space, allowing Horndeski gravity and general relativity to be distinguishable in the said space, and opening up the possibility of potential modifications to the Kerr metric.

Keywords: Black hole physics, Galactic center, Gravitation, Gravitational lensing, Astrophysical black holes
Inverse Multiview. I. Multicalibrator Inverse Phase Referencing for Microarcsecond Very Long Baseline Interferometry Astrometry. Very Long Baseline Interferometry (VLBI) astrometry is a well established technique for achieving ±10 μas parallax accuracies at frequencies well above 10 GHz. At lower frequencies, uncompensated interferometer delays associated with the ionosphere play the dominant role in limiting the astrometric accuracy. Multiview is a novel VLBI calibration method, which uses observations of multiple quasars to accurately model and remove time-variable, directional-dependent changes to the interferometer delay. Here we extend the Multiview technique by phase-referencing data to the target source ("inverse Multiview") and test its performance. Multiple observations with a four-antenna VLBI array operating at 8.3 GHz show single-epoch astrometric accuracies near 20 μas for target-reference quasar separations up to about 7°. This represents an improvement in astrometric accuracy by up to an order of magnitude compared to standard phase-referencing.

Keywords: Very long baseline interferometry, Trigonometric parallax, Radio astrometry, Proper motions
Implications for Additional Plasma Heating Driving the Extreme-ultraviolet Late Phase of a Solar Flare with Microwave Imaging Spectroscopy. Extreme-ultraviolet late phase (ELP) refers to the second extreme-ultraviolet (EUV) radiation enhancement observed in certain solar flares, which usually occurs tens of minutes to several hours after the peak of soft X-ray emission. The coronal loop system that hosts the ELP emission is often different from the main flaring arcade, and the enhanced EUV emission therein may imply an additional heating process. However, the origin of the ELP remains rather unclear. Here we present the analysis of a C1.4 flare that features such an ELP, which is also observed in microwave wavelengths by the Expanded Owens Valley Solar Array. Similar to the case of the ELP, we find a gradual microwave enhancement that occurs about 3 minutes after the main impulsive phase microwave peaks. Radio sources coincide with both foot points of the ELP loops and spectral fits on the time-varying microwave spectra demonstrate a clear deviation of the electron distribution from the Maxwellian case, which could result from injected nonthermal electrons or nonuniform heating to the footpoint plasma. We further point out that the delayed microwave enhancement suggests the presence of an additional heating process, which could be responsible for the evaporation of heated plasma that fills the ELP loops, producing the prolonged ELP emission.

Keywords: Solar radio flares, Solar physics, Solar extreme ultraviolet emission
A Bayesian Population Model for the Observed Dust Attenuation in Galaxies. Dust plays a pivotal role in determining the observed spectral energy distribution (SED) of galaxies. Yet our understanding of dust attenuation is limited and our observations suffer from the dust-metallicity-age degeneracy in SED fitting (single galaxies), large individual variances (ensemble measurements), and the difficulty in properly dealing with uncertainties (statistical considerations). In this study, we create a population Bayesian model to rigorously account for correlated variables and non-Gaussian error distributions and demonstrate the improvement over a simple Bayesian model. We employ a flexible 5D linear interpolation model for the parameters that control dust attenuation curves as a function of stellar mass, star formation rate (SFR), metallicity, redshift, and inclination. Our setup allows us to determine the complex relationships between dust attenuation and these galaxy properties simultaneously. Using Prospector fits of nearly 30,000 3D-Hubble Space Telescope galaxies, we find that the attenuation slope (n) flattens with increasing optical depth (τ), though less so than in previous studies. τ increases strongly with SFR, though when $\mathrm{log}(\mathrm{SFR})\lesssim 0$ , τ remains roughly constant over a wide range of stellar masses. Edge-on galaxies tend to have larger τ than face-on galaxies, but only for $\mathrm{log}({M}_{* })\gtrsim 10$ , reflecting the lack of triaxiality for low-mass galaxies. Redshift evolution of dust attenuation is strongest for low-mass, low-SFR galaxies, with higher optical depths but flatter curves at high redshift. Finally, n has a complex relationship with stellar mass, highlighting the intricacies of the star-dust geometry. We have publicly released software for users to access our population model.

Keywords: Galaxy evolution, Spectral energy distribution, Hierarchical models, Interstellar dust extinction