adsabs/SciX_UAT_keywords huggingface dataset:
Performance of SK-Gd's Upgraded Real-time Supernova Monitoring System

Among multimessenger observations of the next Galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. In 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and has achieved a Gd concentration of 0.033%, resulting in enhanced neutron detection capability, which in turn enables more accurate determination of the supernova direction. Accordingly, SK-Gd's real-time supernova monitoring system has been upgraded. SK_SN Notice, a warning system that works together with this monitoring system, was released on 2021 December 13, and is available through GCN Notices. When the monitoring system detects an SN-like burst of events, SK_SN Notice will automatically distribute an alarm with the reconstructed direction to the supernova candidate within a few minutes. In this paper, we present a systematic study of SK-Gd's response to a simulated Galactic SN. Assuming a supernova situated at 10 kpc, neutrino fluxes from six supernova models are used to characterize SK-Gd's pointing accuracy using the same tools as the online monitoring system. The pointing accuracy is found to vary from 3° to 7° depending on the models. However, if the supernova is closer than 10 kpc, SK_SN Notice can issue an alarm with three-degree accuracy, which will benefit follow-up observations by optical telescopes with large fields of view.

Keywords: core-collapse supernovae; supernova neutrinos; particle astrophysics
Revisiting Galaxy Evolution in Morphology in the Cosmic Evolution Survey Field (COSMOS-ReGEM). I. Merging Galaxies

We revisit the evolution of galaxy morphology in the Cosmic Evolution Survey field over the redshift range 0.2 ≤ z ≤ 1, using a large and complete sample of 33,605 galaxies with a stellar mass of log(M */M ⊙) > 9.5 with significantly improved redshifts and comprehensive nonparametric morphological parameters. Our sample has 13,881 (~41.3%) galaxies with reliable spectroscopic redshifts and more accurate photometric redshifts with a σ NMAD ~ 0.005. This paper is the first in a series that investigates merging galaxies and their properties. We identify 3594 major merging galaxies through visual inspection and find 1737 massive galaxy pairs with log(M */M ⊙) >10.1. Among the family of nonparametric morphological parameters including C, A, S, Gini, M 20, A O, and D O, we find that the outer asymmetry parameter A O and the second-order momentum parameter M 20 are the best tracers of merging features compared to other combinations. Hence, we propose a criterion for selecting candidates of violently star-forming mergers: M 20 > - 3A O + 3 at 0.2 < z < 0.6 and M 20 > - 6A O + 3.7 at 0.6 < z < 1.0. Furthermore, we show that both the visual merger sample and the pair sample exhibit a similar evolution in the merger rate at z < 1, with ${\mathfrak{R}}\sim {(1+z)}^{1.79\pm 0.13}$ for the visual merger sample and ${\mathfrak{R}}\sim {(1+z)}^{2.02\pm 0.42}$ for the pair sample. The visual merger sample has a specific star formation rate that is about 0.16 dex higher than that of nonmerger galaxies, whereas no significant star formation excess is observed in the pair sample. This suggests that the effects of mergers on star formation differ at different merger stages.

Keywords: galaxy mergers; galaxy pairs; galaxy evolution; galaxy classification systems
Machine-learning Prediction of Infrared Spectra of Interstellar Polycyclic Aromatic Hydrocarbons

We design and train a neural network (NN) model to efficiently predict the infrared spectra of interstellar polycyclic aromatic hydrocarbons with a computational cost many orders of magnitude lower than what a first-principles calculation would demand. The input to the NN is based on the Morgan fingerprints extracted from the skeletal formulas of the molecules and does not require precise geometrical information such as interatomic distances. The model shows excellent predictive skill for out-of-sample inputs, making it suitable for improving the mixture models currently used for understanding the chemical composition and evolution of the interstellar medium. We also identify the constraints to its applicability caused by the limited diversity of the training data and estimate the prediction errors using a ensemble of NNs trained on subsets of the data. With help from other machine-learning methods like random forests, we dissect the role of different chemical features in this prediction. The power of these topological descriptors is demonstrated by the limited effect of including detailed geometrical information in the form of Coulomb matrix eigenvalues.

Keywords: polycyclic aromatic hydrocarbons; interstellar molecules; infrared astronomy; neural networks
Polarimetry of the Total Lunar Eclipse on 2022 November 8

We have measured the degree of linear polarization of the Moon during its total eclipse on 2022 November 8, and found P ≈ -2% in the V filter. The plane of preferential polarization was oriented at ~36° counting clockwise from the lunar equator. These measurements suggest global asymmetry in the spatial distribution of aerosol particles in the uppermost atmosphere of Earth, with their net linear polarization being P ≈ -6.5%.

Keywords: polarimetry; the moon; atmospheric science; earth atmosphere; lunar eclipses
Shedding New Light on Weak Emission-line Quasars in the C IV-Hβ Parameter Space

Weak emission-line quasars (WLQs) are a subset of type 1 quasars that exhibit extremely weak Lyα + N V λ1240 and/or C IV λ1549 emission lines. We investigate the relationship between emission-line properties and accretion rate for a sample of 230 "ordinary" type 1 quasars and 18 WLQs at z < 0.5 and 1.5 < z < 3.5 that have rest-frame ultraviolet and optical spectral measurements. We apply a correction to the Hβ-based black hole mass (M BH) estimates of these quasars using the strength of the optical Fe II emission. We confirm previous findings that WLQs' M BH values are overestimated by up to an order of magnitude using the traditional broad-emission-line region size-luminosity relation. With this M BH correction, we find a significant correlation between Hβ-based Eddington luminosity ratios and a combination of the rest-frame C IV equivalent width and C IV blueshift with respect to the systemic redshift. This correlation holds for both ordinary quasars and WLQs, which suggests that the two-dimensional C IV parameter space can serve as an indicator of accretion rate in all type 1 quasars across a wide range of spectral properties.

Keywords: quasars; active galactic nuclei; supermassive black holes
FORECASTOR. I. Finding Optics Requirements and Exposure Times for the Cosmological Advanced Survey Telescope for Optical and UV Research Mission

The Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR) is a proposed Canadian-led 1 m class space telescope that will carry out ultraviolet and blue optical wide-field imaging, spectroscopy, and photometry. CASTOR will provide an essential bridge in the post-Hubble era, preventing a protracted UV-optical gap in space astronomy and enabling an enormous range of discovery opportunities from the solar system to the nature of the cosmos, in conjunction with the other great wide-field observatories of the next decade (e.g., Euclid, Roman, Vera Rubin). FORECASTOR (Finding Optics Requirements and Exposure times for CASTOR) will supply a coordinated suite of mission-planning tools that will serve as the one-stop shop for proposal preparation, data reduction, and analysis for the CASTOR mission. We present the first of these tools: a pixel-based, user-friendly, extensible, multi-mission exposure time calculator built in Python, including a modern browser-based graphical user interface that updates in real time. We then provide several illustrative examples of FORECASTOR's use that advance the design of planned legacy surveys for the CASTOR mission: a search for the most massive white dwarfs in the Magellanic Clouds, a study of the frequency of flaring activity in M stars and their distribution and impacts on habitability of exoplanets, mapping the proper motions of faint stars in the Milky Way, wide and deep galaxy surveys, and time-domain studies of active galactic nuclei.

Keywords: galaxies; m stars; photometry; proper motions; ultraviolet telescopes; white dwarf stars
Search for Lensing Signatures in the Gravitational-Wave Observations from the First Half of LIGO–Virgo's Third Observing Run

We search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo during O3a, the first half of their third observing run. We study: (1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; (2) how the interpretation of individual high-mass events would change if they were found to be lensed; (3) the possibility of multiple images due to strong lensing by galaxies or galaxy clusters; and (4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses.

Keywords: gravitational wave astronomy; gravitational wave sources; astrophysical black holes; gravitational waves; gravitational wave detectors; gravitational lensing; strong gravitational lensing; weak gravitational lensing; gravitational microlensing
Observational Analysis and Numerical Modeling of the Solar Wind Fluctuation Spectra during Intervals of Plasma Instability

We perform a statistical analysis of observed magnetic spectra in the solar wind at 1 au with localized power elevations above the level of the ambient turbulent fluctuations. We show that the elevations are seen only when the intensity of the ambient fluctuations is sufficiently low. Assuming that the spectral elevations are caused by thermal-ion instabilities, this suggests that on average the effect of the solar wind background is strong enough to suppress the instability or obscure it or both. We then carry out nonlinear numerical simulations with particle ions and an electron fluid to model a thermal-ion instability coexisting with an ambient turbulence. The parameters of the simulation are taken from a known solar wind interval where an instability was assumed to exist based on the linear theory and a bi-Maxwellian fit of the observed distribution with core and secondary-beam protons. The numerical model closely matches the position of the observed spectral elevation in the wavenumber space. This confirms that the thermal-ion instability is responsible for the elevation. At the same time, the magnitude of the elevation turns out to be smaller than in the real solar wind. When higher intensity of the turbulence is used in the simulation, which is typical of solar wind in general, the power elevation is no longer seen. This is in agreement with the reduced observability of the elevations at higher intensities. However, the simulations show that the turbulence does not simply obscure the instability but also lowers its saturation level.

Keywords: space plasmas; interplanetary turbulence; solar wind
No Need for Extreme Stellar Masses at z 7: A Test-case Study of COS-87259

Recent controversy regarding the existence of massive ( $\mathrm{log}({M}_{* }/{M}_{\odot })\gtrsim 11$ ) galaxies at z > 6 poses a challenge for galaxy formation theories. Hence, it is of critical importance to understand the effects of SED fitting methods on stellar mass estimates of Epoch of Reionization galaxies. In this work, we perform a case study on the AGN host galaxy candidate COS-87259, with spectroscopic redshift z spec = 6.853, that is claimed to have an extremely high stellar mass of $\mathrm{log}({M}_{* }/{M}_{\odot })\sim 11.2$ . We test a suite of different SED fitting algorithms and stellar population models on our independently measured photometry in 17 broad bands for this source. Between five different code setups, the stellar mass estimates for COS-87259 span $\mathrm{log}({M}_{* }/{M}_{\odot })=10.24$ -11.00, while the reduced χ 2 values of the fits are all close to unity within ${\rm{\Delta }}{\chi }_{\nu }^{2}=1.2$ , such that the quality of the SED fits is basically indistinguishable. Only when we adopt a nonparametric star formation history model within PROSPECTOR do we retrieve a stellar mass exceeding $\mathrm{log}({M}_{* }/{M}_{\odot })=11$ . Although the derived stellar masses change when using previously reported photometry for this source, the nonparametric SED-fitting method always yields the highest values. As these models are becoming increasingly popular for James Webb Space Telescope high-redshift science, we stress the absolute importance of testing various SED fitting routines particularly on apparently very massive galaxies at such high redshifts.

Keywords: high-redshift galaxies; stellar masses; spectral energy distribution
Discovery of Raman-scattered He II λ6545 in the Planetary Nebulae NGC 6886 and NGC 6881

Young planetary nebulae (PNe) retain a large amount of neutral material that was shed in the previous asymptotic giant branch stage. The thick H I region in young PNe can be effectively probed by illuminating far-UV radiation that may be inelastically scattered to appear in the optical region. Raman-scattered features are unique spectroscopic tracers of neutral regions that can be used to investigate the mass-loss process in young PNe. We conduct high-resolution spectroscopy of young PNe using the Bohyunsan Observatory Echelle Spectrograph (BOES) and report the discovery of a Raman-scattered He II feature at 6545 Å in NGC 6886 and NGC 6881. The Raman-scattered He II features have been found in only five PNe so far, and in particular, it is the first direct detection of an H I component in NGC 6881. The Raman He II λ6545 features in the two PNe are observed to be redshifted with respect to He II λ6560, indicating that the neutral regions are expanding. We perform line profile analyses using the grid-based Monte Carlo code "STaRS" by assuming a neutral hydrogen region in the shape of a partial spherical shell expanding radially. The profiles are well fitted with the model parameters of covering factor CF = 0.3, H I column density NHI = 5 × 1020 cm-2, and expansion speed ${v}_{\exp }=25\,\,\mathrm{km}\,{{\rm{s}}}^{-1}$ for NGC 6886 and CF = 0.6, NHI = 3 × 1020 cm-2, and ${v}_{\exp }=30\,\mathrm{km}\,{{\rm{s}}}^{-1}$ for NGC 6881, respectively.

Keywords: planetary nebulae; stellar mass loss; h i regions
AI-enhanced Citizen Science Discovery of an Active Asteroid: (410590) 2008 GB140

We report the discovery of cometary activity emanating from Main-belt asteroid 410590 (2008 GB140), a finding facilitated, for the first time, by an artificial intelligence (AI) assistant. The assistant, TailNet, is a prototype we designed to enhance volunteer efforts of our Citizen Science project Active Asteroids, a NASA Partner program hosted on the Zooniverse platform. Our follow-up investigation revealed eight Dark Energy Camera images showing 2008 GB140 with a tail spanning UT 2023 April 23–UT 2023 July 3, when the object was inbound to perihelion. We classify 2008 GB140 as an active asteroid and a candidate Main-belt comet (MBC)—a main-belt asteroid that undergoes volatile sublimation-driven activity. Notably, 2008 GB140 is presently near perihelion, thus the object is a prime target for follow-up observations to further characterize its activity.

Keywords: asteroids; comae; comet tails; convolutional neural networks
Recent Formation of a Spiral Disk Hosting Progenitor Globular Clusters at the Center of the Perseus Brightest Cluster Galaxy. II. Progenitor Globular Clusters

We address the nature and origin of super star clusters (SSCs) discovered by Holtzman et al. within a radius of ~5 kpc from the center of NGC 1275, the giant elliptical galaxy at the center of the Perseus Cluster. We show that, in contrast with the much more numerous population of SSCs subsequently discovered up to ~30 kpc from the center of this galaxy, the central SSC population have maximal masses an order of magnitude higher and a mass function with a shallower power-law slope. Furthermore, whereas the outer SSC population have ages spanning a few Myr to at least ~1 Gyr, the central SSC population have ages strongly concentrated around ~500 Myr with a 1σ dispersion of ~100 Myr. These SSCs share a close spatial and temporal relationship with the "central spiral," which also has a radius ~5 kpc centered on NGC 1275 and a characteristic stellar age of ~150 Myr. We argue that both the central SSC population and the central spiral formed from gas deposited by a residual cooling flow, with the SSCs forming first followed by the formation of the stellar body of the central spiral ~300-400 Myr later. The ages of the central SSC population imply that they are able to withstand very strong tidal fields near the center of NGC 1275, making them genuine progenitor globular clusters. Evidently, a spiral disk hosting progenitor globular clusters has recently formed at the center of a giant elliptical galaxy.

Keywords: star clusters; perseus cluster; brightest cluster galaxies; cooling flows
Direct Observations of Reconnection Fronts in Earth's Turbulent Magnetosheath

Reconnection fronts (RFs), ion-scale magnetic transients characterized by dramatic enhancement of reconnected magnetic fields, have been documented as crucial energy transfer regions during magnetic reconnection. RFs have hitherto been observed only in the planetary (e.g., Earth, Saturn, Mars, and Venus) magnetotails. Whether RFs can exist in other magnetospheric regions remains unclear. Here, using high-cadence data from NASA's Magnetospheric Multiscale mission, we present the first observation of successive RFs in Earth's turbulent magnetosheath. The RFs were detected inside an ion diffusion region and several di (ion inertial length) away from reconnection X-line. In addition, we find that the strongest energy conversion occurs at the RF rather than at the X-line. The present observation indicates that RFs may be universal in the planetary magnetosphere and play a crucial role in the reconnection dynamics.

Keywords: space plasmas
Integral Field Spectroscopy of 13 Tidal Disruption Event Hosts from the Zwicky Transient Facility Survey

The host galaxies of tidal disruption events (TDEs) have been shown to possess peculiar properties, including high central light concentrations, unusual star formation histories, and "green" colors. The ubiquity of these large-scale galaxy characteristics among TDE host populations suggests that they may serve to boost the TDE rate in such galaxies by influencing the nuclear stellar dynamics. We present the first population study of integral field spectroscopy for 13 TDE host galaxies across all spectral classes and X-ray brightnesses with the purpose of investigating their large-scale properties. We derive the black hole masses via stellar kinematics (i.e., the M-σ relation) and find masses in the range $5.0\lesssim \mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })\lesssim 8.0$ , with a distribution dominated by black holes with M BH ~ 106 M ⊙. We find one object with M BH ≳ 108 M ⊙, above the "Hills mass", which if the disrupted star was of solar type, allows a lower limit of a ≳ 0.16 to be placed on its spin, lending further support to the proposed connection between featureless TDEs and jetted TDEs. We also explore the level of rotational support in the TDE hosts, quantified by (V/σ) e , a parameter that has been shown to correlate with the stellar age and may explain the peculiar host-galaxy preferences of TDEs. We find that the TDE hosts exhibit a broad range in (V/σ) e following a similar distribution as E + A galaxies, which have been shown to be overrepresented among TDE host populations.

Keywords: tidal disruption; stellar kinematics; galaxy stellar content; supermassive black holes; scaling relations; black holes
An Exploration of Tensor Virial Equilibrium in Magnetized Molecular Cloud Cores

PolCat is a software package designed to generate and constrain models of triaxial, magnetized molecular cloud cores using submillimeter polarization and continuum intensity data. Such models often compare well with observational data, but they are mathematically degenerate. As a result, many allowed models are either very elongated or flattened, and far from virial equilibrium. We present a tensor virial analysis of PolCat models with the aim of developing an optional new regularization constraint that can be used on the fly during the PolCat modeling process. This constraint is intended to guide PolCat toward models that are in or close to equilibrium on all three principal axes. While we have found the expected families of spheroidal solutions in tensor virial balance, we have also found a population of triaxial cores that are in three-axis tensor virial equilibrium. We find that models generated using the virial constraint have much more realistic shapes, with very elongated or flattened solutions now absent. Thus, these show that the tensor virial constraint may be useful for restricting PolCat's solution space to more realistic models, thereby also reducing the degeneracy inherent in our approach. We also perform a Monte Carlo analysis to predict the range of projected axis ratios present in the population of equilibrium solutions to suggest how these cores may appear when observed.

Keywords: molecular clouds; astronomical models; magnetic fields; gravitational equilibrium; submillimeter astronomy; computational methods
Physical Properties of 5000 Cool Large Magellanic Cloud Supergiants with Gaia XP Spectra: A Detailed Portrait of the Upper H-R Diagram Hints at Missing Supernova Progenitors

Characterizing the physical properties of cool supergiants allows us to probe the final stages of a massive star's evolution before it undergoes core collapse. Despite their importance, the fundamental properties of these stars- $\mathrm{log}{T}_{\mathrm{eff}}$ and $\mathrm{log}L/{L}_{\odot }$ -are only known for a limited number of objects. The third data release of the Gaia mission contains precise photometry and low-resolution spectroscopy of hundreds of cool supergiants in the LMC with well-constrained properties. Using these data, we train a simple and easily interpretable machine-learning model to regress effective temperatures and luminosities with high accuracy and precision comparable to the training data. We then apply our model to 5000 cool supergiants, many of which have no previously published T eff or L estimates. The resulting Hertzprung-Russell diagram is well populated, allowing us to study the distribution of cool supergiants in great detail. Examining the luminosity functions of our sample, we find a notable flattening in the luminosity function of yellow supergiants above $\mathrm{log}L/{L}_{\odot }=5$ , and a corresponding steepening of the red supergiant luminosity function. We place this finding in context with previous results and present its implications for the infamous red supergiant problem.

Keywords: stellar properties; stellar effective temperatures; stellar luminosities; regression; multivariate analysis; spectroscopy; large magellanic cloud; late-type supergiant stars; supergiant stars