Sazuna/UAT_keywords huggingface dataset:
Red Spiral Galaxies at Cosmic Noon Unveiled in the First JWST Image. In the first image of the James Webb Space Telescope (JWST) of SMACS J0723.3-7327, one of the most outstanding features is the emergence of a large number of red spiral galaxies, because such red spiral galaxies are only a few percent in the number fraction among nearby spiral galaxies. While these apparently red galaxies were already detected with the Spitzer Space Telescope at ~3-4 μm, the revolutionized view from the JWST's unprecedented spatial resolution has unveiled their hidden spiral morphology for the first time. Within the red spiral galaxies, we focus on the two reddest galaxies that are very faint in the &lt;0.9 μ m bands and show red colors in the 2-4 μm bands. Our study finds that the two extremely red spiral galaxies are likely to be in the cosmic noon (1 &lt; z &lt; 3). One of the extremely red spiral galaxies is more likely to be a passive galaxy having moderate dust reddening (i.e., ~zero star formation rate with AV ~ 1 mag). The other is consistent with both passive and dusty starburst solutions (i.e., star formation rate &gt; 100 M⊙ yr-1 with AV ~ 3 mag). These "red spiral" galaxies would be an interesting, potentially new population of galaxies, as we start to see their detailed morphology using the JWST, for the first time.

Keywords: Galaxy stellar disks, Galaxy formation, Spiral galaxies, Galaxy structure, Galaxy evolution
A Strong Shock During a Nova Outburst: An Origin of Multiple Velocity Systems in Optical Spectra and of High-energy Emissions. We propose a theoretical explanation of absorption/emission line systems in classical novae based on a fully self-consistent nova explosion model. We found that a reverse shock is formed far outside the photosphere (≳1013 cm) because later-ejected mass with a faster velocity collides with earlier-ejected matter. Optically thick winds blow continuously at a rate of ~10-4 M ⊙ yr-1 near the optical maximum, but its velocity decreases toward the optical maximum and increases afterward, so that the shock arises only after the optical maximum. The nova ejecta is divided by the shock into three parts, the outermost expanding gas (earliest wind before maximum), shocked shell, and inner fast wind, which respectively contribute to pre-maximum, principal, and diffuse-enhanced absorption/emission line systems. A large part of nova ejecta is eventually confined to the shocked shell. The appearance of the principal system is consistent with the emergence of a shock. This shock is strong enough to explain thermal hard X-ray emissions. The shocked layer has a high temperature of kT sh ~ 1 keV $\,\times \,{({({v}_{\mathrm{wind}}-{v}_{\mathrm{shock}})/1000\,\mathrm{km}\,{{\rm{s}}}^{-1})}^{2}=1\ \mathrm{keV}\times (({v}_{{\rm{d}}}-{v}_{{\rm{p}}})/1000\,\mathrm{km}\,{{\rm{s}}}^{-1})}^{2}$ , where v d - v p is the velocity difference between the diffuse-enhanced (v d) and principal (v p) systems. We compare a 1.3 M ⊙ white dwarf model with the observational properties of the GeV gamma-ray detected classical nova V5856 Sgr (ASASSN-16ma) and discuss what kind of novae can produce GeV gamma-ray emissions.

Keywords: X-ray astronomy, High energy astrophysics, White dwarf stars, Shocks, Cataclysmic variable stars, Gamma-ray astronomy, Classical novae
On the Stability of Tidal Streams in Action Space. In the Gaia era it is increasingly apparent that traditional static, parameterized models are insufficient to describe the mass distribution of our complex, dynamically evolving Milky Way (MW). In this work, we compare different time-evolving and time-independent representations of the gravitational potentials of simulated MW-mass galaxies from the FIRE-2 suite of cosmological-baryonic simulations. Using these potentials, we calculate actions for star particles in tidal streams around three galaxies with varying merger histories at each snapshot from 7 Gyr ago to the present day. We determine the action-space coherence preserved by each model using the Kullback-Leibler divergence to gauge the degree of clustering in actions and the relative stability of the clusters over time. We find that all models produce a clustered action space for simulations with no significant mergers. However, a massive (mass ratio prior to infall more similar than 1:8) interacting galaxy not present in the model will result in mischaracterized orbits for stars most affected by the interaction. The locations of the action space clusters (i.e., the orbits of the stream stars) are only preserved by the time-evolving model, while the time-independent models can lose significant amounts of information as soon as 0.5-1 Gyr ago, even if the system does not undergo a significant merger. Our results imply that reverse-integration of stream orbits in the MW using a fixed potential is likely to give incorrect results if integrated longer than 0.5 Gyr into the past.

Keywords: Galaxy interactions, Dark matter, Stellar streams
The Impact of Binaries on the Dynamical Mass Estimate of Dwarf Galaxies. Binary stars are recognized to be important in driving the dynamical evolution of stellar systems and also in determining some of their observational features. In this study, we explore the role that binary stars have in modulating the estimates of the velocity dispersion of stellar systems. To this aim, we developed a tool that allows investigation of the dependence of synthetic velocity dispersion on a number of crucial quantities characterizing the binary content: binary fraction and the distributions of their mass ratio, eccentricity, and semimajor axis. As an application, we evaluate the impact that binary stars have on the estimation of the dynamical mass of dwarf spheroidal and ultrafaint dwarf galaxies, finding that it can be particularly relevant, especially for low-mass and low-density systems. These results bear profound implications for the interpretation of the measured velocity dispersion in such systems, since it weakens or relieves the claim for the need of large amounts of dark matter.

Keywords: Dwarf galaxies, Binary stars, Dark matter
Where Did the Outskirts Go? Outer Stellar Halos as a Sensitive Probe of Supernova Feedback. A recent comparison by Merritt of simulated and observed Milky Way-mass galaxies has identified a significant tension between the outskirts (r &gt; 20 kpc) of the stellar halos in simulated and observed galaxies. Using observations from the Dragonfly telescope and simulated galaxies from the Illustris-TNG100 project, Merritt found that the outskirts of stellar halos in simulated galaxies have surface densities 1-2 dex higher than those of observed galaxies. In this paper, we compare two suites of 15 simulated Milky Way-like galaxies, each drawn from the same initial conditions, simulated with the same hydrodynamical code, but with two different models for feedback from supernovae. We find that the McMaster Unbiased Galaxy Simulations (MUGS), which use an older "delayed-cooling" model for feedback, also produce too much stellar mass in the outskirts of the halo, with median surface densities well above observational constraints. The MUGS2 simulations, which instead use a new, physically motivated "superbubble" model for stellar feedback, have 1-2 dex lower outer stellar halo masses and surface densities. The MUGS2 simulations generally match both the median surface density profile as well as the scatter in stellar halo surface density profiles seen in observed stellar halos. We conclude that there is no "missing outskirts" problem in cosmological simulations, provided that supernova feedback is modeled in a way that allows it to efficiently regulate star formation in the low-mass progenitor environments of stellar halo outskirts.

Keywords: Galaxy formation, Stellar feedback, Galaxy structure, Galaxy stellar halos, Astronomical simulations
A Submillimeter Survey of Faint Galaxies behind 10 Strong Lensing Clusters. We present deep SCUBA-2 450 μm and 850 μm imaging of 10 strong lensing clusters. We provide a &gt;4σ SCUBA-2 850 μm catalog of the 404 sources lying within a radius of $4\buildrel{\,\prime}\over{.} 5$ from the cluster centers. We also provide catalogs of the &gt;4.5σ Atacama Large Millimeter/submillimeter Array (ALMA) 850 μm detections in the clusters A370, MACSJ1149.5+2223, and MACSJ0717.5+3745 from our targeted ALMA observations, along with catalogs of all other &gt;4.5σ ALMA (mostly 1.2 mm) detections in any of our cluster fields from archival ALMA observations. For the ALMA detections, we give spectroscopic or photometric redshifts, where available, from our own Keck observations or from the literature. We confirm the use of the 450-850 μm flux ratio for estimating redshifts. We use lens models to determine magnifications, most of which are in the 1.5-4 range. After supplementing the ALMA cluster sample with Chandra Deep Field ALMA and Submillimeter Array samples, we find no evidence for evolution in the redshift distribution of submillimeter galaxies down to demagnified 850 μm fluxes of 0.5 mJy. Given this result, we conclude that our observed trend of increasing F160W to 850 μm flux ratio from brighter to fainter demagnified 850 μm flux results from the fainter submillimeter galaxies having less extinction. However, there is wide spread in this relation, including the presence of some optical/near-infrared dark galaxies down to fluxes below 1 mJy. Finally, with insights from our ALMA analysis, we analyze our SCUBA-2 sample and present 55 850 μm bright z &gt; 4 candidates.

Keywords: Far infrared astronomy
The 2019 Outburst of the 2005 Classical Nova V1047 Cen: A Record Breaking Dwarf Nova Outburst or a New Phenomenon?. We present a detailed study of the 2019 outburst of the cataclysmic variable V1047 Cen, which hosted a classical nova eruption in 2005. The peculiar outburst occurred 14 yr after the classical nova event and lasted for more than 400 days, reaching an amplitude of around 6 magnitudes in the optical. Early spectral follow-up revealed what could be a dwarf nova (accretion disk instability) outburst. However, the outburst duration, high-velocity (&gt;2000 km s-1) features in the optical line profiles, luminous optical emission, and presence of prominent long-lasting radio emission together suggest a phenomenon more exotic and energetic than a dwarf nova outburst. The outburst amplitude, radiated energy, and spectral evolution are also not consistent with a classical nova eruption. There are similarities between V1047 Cen's 2019 outburst and those of classical symbiotic stars, but pre-2005 images of the field of V1047 Cen indicate that the system likely hosts a dwarf companion, implying a typical cataclysmic variable system. Based on our multiwavelength observations, we suggest that the outburst may have started with a brightening of the disk due to enhanced mass transfer or disk instability, possibly leading to enhanced nuclear shell burning on the white dwarf, which was already experiencing some level of quasi-steady shell burning. This eventually led to the generation of a wind and/or bipolar, collimated outflows. The 2019 outburst of V1047 Cen appears to be unique, and nothing similar has been observed in a typical cataclysmic variable system before, hinting at a potentially new astrophysical phenomenon.

Keywords: White dwarf stars, Dwarf novae, Novae, Compact objects, Symbiotic binary stars, Classical novae
Timing Six Energetic Rotation-powered X-Ray Pulsars, Including the Fast-spinning Young PSR J0058-7218 and Big Glitcher PSR J0537-6910. Measuring a pulsar's rotational evolution is crucial to understanding the nature of the pulsar. Here, we provide updated timing models for the rotational evolution of six pulsars, five of which are rotation phase-connected using primarily NICER X-ray data. For the newly discovered fast energetic young pulsar, PSR J0058-7218, we increase the baseline of its timing model from 1.4 days to 8 months and not only measure more precisely its spin-down rate $\dot{\nu }=(-6.2324\pm 0.0001)\times {10}^{-11}\,\mathrm{Hz}\,{{\rm{s}}}^{-1}$ but also for the first time the second time derivative of its spin rate $\ddot{\nu }=(4.2\pm 0.2)\times {10}^{-21}\,\mathrm{Hz}\,{{\rm{s}}}^{-2}$ . For the fastest and most energetic young pulsar, PSR J0537-6910 (with a 16 ms spin period), we detect four more glitches, for a total of 15 glitches over 4.5 yr of NICER monitoring, and show that its spin-down behavior continues to set this pulsar apart from all others, including a long-term braking index n = -1.234 ± 0.009 and interglitch braking indices that asymptote to ≲7 for long times after a glitch. For PSR J1101-6101, we measure a much more accurate spin-down rate that agrees with a previous value measured without phase connection. For PSR J1412+7922 (also known as Calvera), we extend the baseline of its timing model from our previous 1 yr model to 4.4 yr, and for PSR J1849-0001, we extend the baseline from 1.5 to 4.7 yr. We also present a long-term timing model of the energetic pulsar PSR J1813-1749, by fitting previous radio and X-ray spin frequencies from 2009-2019 and new ones measured here using 2018 NuSTAR and 2021 Chandra data.

Keywords: Neutron stars, Ephemerides, Rotation powered pulsars, Pulsars, X-ray sources
Lanthanide Features in Near-infrared Spectra of Kilonovae. The observations of GW170817/AT2017gfo have provided us with evidence that binary neutron star mergers are sites of r-process nucleosynthesis. However, the observed signatures in the spectra of GW170817/AT2017gfo have not been fully decoded, especially in the near-infrared (NIR) wavelengths. In this paper, we investigate the kilonova spectra over the entire wavelength range with the aim of elemental identification. We systematically calculate the strength of bound-bound transitions by constructing a hybrid line list that is accurate for important strong transitions and complete for weak transitions. We find that the elements on the left side of the periodic table, such as Ca, Sr, Y, Zr, Ba, La, and Ce, tend to produce prominent absorption lines in the spectra. This is because such elements have a small number of valence electrons and low-lying energy levels, resulting in strong transitions. By performing self-consistent radiative transfer simulations for the entire ejecta, we find that La III and Ce III appear in the NIR spectra, which can explain the absorption features at λ ~ 12000-14000 Å in the spectra of GW170817/AT2017gfo. The mass fractions of La and Ce are estimated to be &gt;2 × 10-6 and ~(1-100) × 10-5, respectively. An actinide element Th can also be a source of absorption as the atomic structure is analogous to that of Ce. However, we show that Th III features are less prominent in the spectra because of the denser energy levels of actinides compared to those of lanthanides.

Keywords: Neutron stars, Radiative transfer simulations, R-process, Atomic physics
A Comparison of Global Magnetofrictional Simulations of the 2015 March 20 Solar Eclipse. The solar corona exhibits a wide range of phenomena, from highly non-potential objects such as solar filaments to near-potential structures such as the open magnetic flux. For any global model to be useful in space weather applications, the model must on a single day reproduce all of these phenomena in the same simulation, using the same set of coronal physics and parameters. The purpose of the present paper is to evaluate whether the evolving magnetofrictional model can achieve this goal. Twenty-eight separate simulations are analyzed, where each tries to reproduce both highly non-potential and near-potential phenomena observed in the solar corona on the same day. This day is chosen to be 2015 March 20, the date of the solar eclipse. The study evaluates how the cadence of bipole data, ideal or nonideal coronal physics, and the variety of helicity injection mechanisms affect the accuracy of the simulations. Results show that significantly better agreement arises when using Advective Flux Transport (AFT) synoptic maps to drive the simulations, as compared to 27-day Carrington rotation synoptic maps. Using the nonideal effect of hyperdiffusion leads to the worst agreement with all coronal phenomena. Alternatively, when running either ideal or ohmic diffusion simulations with helicity condensation or bipoles with a self-helicity, a good agreement with both on-disk and limb structures can be found. This suggests that future studies aiming to simulate the corona and reproduce multiple phenomena on a given day should use data products such as AFT and avoid using the nonideal physics of hyperdiffusion.

Keywords: Solar magnetic fields, Solar prominences, Solar corona, Solar evolution
Mining the Information Content of Member Galaxies in Halo Mass Modeling. Motivated by previous findings that the magnitude gap between certain satellite galaxies and the central galaxy can be used to improve the estimation of halo mass, we carry out a systematic study of the information content of different member galaxies in the modeling of the host halo mass using a machine-learning approach. We employ data from the hydrodynamical simulation IllustrisTNG and train a random forest algorithm to predict a halo mass from the stellar masses of its member galaxies. Exhaustive feature selection is adopted to disentangle the importance of different galaxy members. We confirm that an additional satellite does improve the halo mass estimation compared to that estimated by the central alone. However, the magnitude of this improvement does not differ significantly using different satellite galaxies. When three galaxies are used in the halo mass prediction, the best combination is always that of the central galaxy with the most massive satellite and the smallest satellite. Furthermore, among the top seven galaxies, the combination of a central galaxy and two or three satellite galaxies gives a near-optimal estimation of halo mass, and further addition of galaxies does not raise the precision of the prediction. We demonstrate that these dependences can be understood from the shape variation of the conditional satellite distribution, with different member galaxies accounting for distinct halo-dependent features in different parts of the cumulative stellar mass function.

Keywords: Stellar mass functions, Galaxy dark matter halos, Random Forests
SALT3-NIR: Taking the Open-source Type Ia Supernova Model to Longer Wavelengths for Next-generation Cosmological Measurements. A large fraction of Type Ia supernova (SN Ia) observations over the next decade will be in the near-infrared (NIR), at wavelengths beyond the reach of the current standard light-curve model for SN Ia cosmology, SALT3 (~2800-8700 Å central filter wavelength). To harness this new SN Ia sample and reduce future light-curve standardization systematic uncertainties, we train SALT3 at NIR wavelengths (SALT3-NIR) up to 2 μm with the open-source model-training software SALTshaker, which can easily accommodate future observations. Using simulated data, we show that the training process constrains the NIR model to ~2%-3% across the phase range (-20 to 50 days). We find that Hubble residual (HR) scatter is smaller using the NIR alone or optical+NIR compared to optical alone, by up to ~30% depending on filter choice (95% confidence). There is significant correlation between NIR light-curve stretch measurements and luminosity, with stretch and color corrections often improving HR scatter by up to ~20%. For SN Ia observations expected from the Roman Space Telescope, SALT3-NIR increases the amount of usable data in the SALT framework by ~20% at redshift z ≲ 0.4 and by ~50% at z ≲ 0.15. The SALT3-NIR model is part of the open-source SNCosmo and SNANA SN Ia cosmology packages.

Keywords: Cosmology, Astronomical models, Type Ia supernovae, Near infrared astronomy
Numerical Simulation of Hot Accretion Flow around Bondi Radius. Previous numerical simulations have shown that strong winds can be produced in the hot accretion flows around black holes. Most of those studies focus only on the region close to the central black hole; therefore it is unclear whether the wind production stops at large radii around Bondi radius. Bu et al. (2016) studied the hot accretion flow around the Bondi radius in the presence of nuclear star gravity. They find that, when the nuclear stars gravity is important-comparable to the black hole gravity, winds cannot be produced around the Bondi radius. However, for some galaxies, the nuclear stars gravity around Bondi radius may not be strong. In this case, whether winds can be produced around Bondi radius is not clear. We study the hot accretion flow around Bondi radius with and without thermal conduction by performing hydrodynamical simulations. We use the virtual particles trajectory method to study whether winds exist based on the simulation data. Our numerical results show that, in the absence of nuclear stars gravity, winds can be produced around Bondi radius, which causes the mass inflow rate to decrease inwards. We confirm the results of Yuan et al. (2012), which indicate this is due to the mass loss of gas via wind rather than convectional motions.

Keywords: Hydrodynamical simulations
Determining the Core Structure and Nuclear Equation of State of Rotating Core-collapse Supernovae with Gravitational Waves by Convolutional Neural Networks. Detecting gravitational waves from a nearby core-collapse supernova would place meaningful constraints on the supernova engine and nuclear equation of state. Here we use convolutional neural network models to identify the core rotational rates, rotation length scales, and the nuclear equation of state (EoS), using the 1824 waveforms from Richers et al. for a 12 solar mass progenitor. A high prediction accuracy for the classifications of the rotation length scales (93%) and the rotational rates (95%) can be achieved using the gravitational-wave signals from -10 to 6 ms core bounce. By including an additional 48 ms signal during the prompt convection phase, we could achieve an accuracy of 96% in the classification of the four main EoS groups. By combining the three models above, we could correctly predict the core rotational rates, rotation length scales, and the EoS at the same time with an accuracy of more than 85%. Finally, applying a transfer-learning method for an additional 74 waveforms from FLASH simulations, we show that our model using Richers' waveforms could successfully predict the rotational rates from Pan's waveforms even for a continuous value with mean absolute errors of 0.32 rad s-1 only. These results demonstrate the much broader parameter regimes to which our model can be applied to identify core-collapse supernova events through gravitational-wave signals.

Keywords: Gravitational wave astronomy, Neutron stars, Black holes, Core-collapse supernovae
The Evolution of the Optical Spectrum of V455 Andromedae throughout the 2007 Superoutburst. V455 And is a dwarf nova with a short orbital period, close to the orbital period minimum. The object underwent its first detected outburst in 2007, brightening from around V = 16.5 all the way to magnitude 8. Outbursts of such amplitude occur exclusively in dwarf novae with short periods (typically P orb ≲ 90 minutes) and are called superoutbursts. The recurrence time of superoutbursts is long (decades), hence only very few have been studied in detail. We succeeded in observing the entire superoutburst of V455 And spectroscopically from the rise to the decline with unprecedented detail. While the light curve of the object throughout the outburst does not seem to differ much from other dwarf novae, its spectroscopic behavior is strikingly different during the transition stage from the absorption-dominated lines to the strong emission one during the rise. We interpret the emergence of the strong emission lines with little radial velocity variations during the superoutburst as evidence of wind from the evaporating disk in this high-inclination system. The evolution of the line profiles from wide to narrow peak separation during the rise, and back at the decline, matches models showing that the peak separation is a function of optical depth in the lines.

Keywords: Cataclysmic variable stars