adsabs/SciX_UAT_keywords huggingface dataset:
Probing the Diversity of Type Ia Supernova Light Curves in the Open Supernova Catalog

The ever-growing sample of observed supernovae (SNe) enhances our capacity for comprehensive SN population studies, providing a richer data set for understanding the diverse characteristics of Type Ia supernovae (SNe Ia) and possibly those of their progenitors. Here, we present a data-driven analysis of observed SN Ia photometric light curves collected in the Open Supernova Catalog. Where available, we add the environmental information from the host galaxy. We focus on identifying subclasses of SNe Ia without imposing the predefined subclasses found in the literature to date. To do so, we employ an implicit rank-minimizing autoencoder neural network for developing low-dimensional data representations, providing a compact representation of the SN light-curve diversity. When we analyze light curves alone, we find that one of our resulting latent variables is strongly correlated with redshift, allowing us to approximately "de-redshift" the other latent variables describing each event. After doing so, we find that three of our latent variables account for ∼95% of the variance in our sample, and provide a natural separation between 91T and 91bg thermonuclear SNe. Of note, the 02cx subclass is not unambiguously delineated from the 91bg sample in our results, nor do either the overluminous 91T or the underluminous 91bg/02cx samples form a clearly distinct population from the broader sample of "other" SN Ia events. We identify the physical characteristics of SN light curves that best distinguish SNe 91T from SNe 91bg and 02cx, and discuss prospects for future refinements and applications to other classes of SNe as well as other transients.

Keywords: type ia supernovae; catalogs; astronomy data analysis; neural networks
The Low-temperature Corona in ESO 511-G030 Revealed by NuSTAR and XMM-Newton

We present the results from a coordinated XMM-Newton + NuSTAR observation of the Seyfert 1 galaxy ESO 511-G030. With this joint monitoring program, we conduct a detailed variability and spectral analysis. The source remained in a low flux and very stable state throughout the observation period, although there are slight fluctuations of flux over long timescales. The broadband (0.3-78 keV) spectrum shows the presence of a power-law continuum with a soft excess below 2 keV, a relatively narrow iron Kα emission (~6.4 keV), and an obvious cutoff at high energies. We find that the soft excess can be modeled by two different possible scenarios: a warm (kT e ~ 0.19 keV) and optically thick (τ = 18-25) Comptonizing corona or a relativistic reflection from a high-density ( $\mathrm{log}[{n}_{{\rm{e}}}/{\mathrm{cm}}^{-3}]=17.1\mbox{--}18.5$ ) inner disk. All models require a low temperature (kT e ~ 13 keV) for the hot corona.

Keywords: accretion; seyfert galaxies; astrophysical black holes; x-ray astronomy
The Structure of Stellar Disks in Isolated Lenticular Galaxies

We have obtained imaging data in two photometric bands, g and r, for a sample of 42 isolated lenticular galaxies with the Las Cumbres Observatory 1 m telescope network. We have analyzed the structure of their large-scale stellar disks. The parameters of surface-brightness distributions have been determined including the radial profile shapes and disk thicknesses. After inspecting the radial brightness profiles, all of the galaxies have been classified into pure exponential (Type I), truncated (Type II), and antitruncated (Type III) disks. By comparing the derived statistics of the radial profile shapes with our previous sample of cluster S0s, we noted a prominent difference between stellar disks of S0s galaxies in quite rarefied environments and in clusters: it is only in sparse environments that Type II disks, with profile truncations, can be found. This finding implies probable different dynamical history of S0 galaxies in different environments. ∗ Based on observations made with the Las Cumbres Observatory telescope network.

Keywords: disk galaxies; lenticular galaxies
Hot Corinos Chemical Diversity: Myth or Reality?

After almost 20 years of hunting, only about a dozen hot corinos, hot regions enriched in interstellar complex organic molecules (iCOMs), are known. Of them, many are binary systems with the two components showing drastically different molecular spectra. Two obvious questions arise. Why are hot corinos so difficult to find and why do their binary components seem chemically different? The answer to both questions could be a high dust opacity that would hide the molecular lines. To test this hypothesis, we observed methanol lines at centimeter wavelengths, where dust opacity is negligible, using the Very Large Array interferometer. We targeted the NGC 1333 IRAS 4A binary system, for which one of the two components, 4A1, has a spectrum deprived of iCOMs lines when observed at millimeter wavelengths, while the other component, 4A2, is very rich in iCOMs. We found that centimeter methanol lines are similarly bright toward 4A1 and 4A2. Their non-LTE analysis indicates gas density and temperature ( $\geqslant 2\times {10}^{6}$ cm-3 and 100-190 K), methanol column density (∼1019 cm-2), and extent (∼35 au in radius) similar in 4A1 and 4A2, proving that both are hot corinos. Furthermore, the comparison with previous methanol line millimeter observations allows us to estimate the optical depth of the dust in front of 4A1 and 4A2, respectively. The obtained values explain the absence of iCOMs line emission toward 4A1 at millimeter wavelengths and indicate that the abundances toward 4A2 are underestimated by ∼30%. Therefore, centimeter observations are crucial for the correct study of hot corinos, their census, and their molecular abundances.

Keywords: interstellar medium; protostars; star formation; chemical abundances; astrochemistry
A New Estimate of the Cosmic Star Formation Density from a Radio-selected Sample, and the Contribution of H-dark Galaxies at z ≥ 3

The star formation rate density (SFRD) history of the universe is well constrained up to redshift z ~ 2. At earlier cosmic epochs, the picture has been largely inferred from UV-selected galaxies (e.g., Lyman-break galaxies; LBGs). However, the inferred star formation rates of LBGs strongly depend on the assumed dust extinction correction, which is not well constrained at high z, while observations in the radio domain are not affected by this issue. In this work we measure the SFRD from a 1.4 GHz selected sample of ~600 galaxies in the GOODS-N field up to redshift ~3.5. We take into account the contribution of active galactic nuclei from the infrared-radio correlation. We measure the radio luminosity function, fitted with a modified Schechter function, and derive the SFRD. The cosmic SFRD shows an increase up to z ~ 2 and then an almost flat plateau up to z ~ 3.5. Our SFRD is in agreement with those from other far-IR/radio surveys and a factor 2 higher than those from LBG samples. We also estimate that galaxies lacking a counterpart in the HST/WFC3 H-band (H-dark) make up ~25% of the ϕ-integrated SFRD relative to the full sample at z ~ 3.2, and up to 58% relative to LBG samples.

Keywords: galaxy formation; galaxy evolution; star formation; radio galaxies
Constraining the Size of the Circumgalactic Medium Using the Transverse Autocorrelation Function of C IV Absorbers in Paired Quasar Spectra

The circumgalactic medium (CGM) plays a vital role in the formation and evolution of galaxies, acting as a lifeline between galaxies and the surrounding intergalactic medium. In this study, we leverage a unique sample of quasar pairs to investigate the properties of the CGM with absorption line tomography. We present a new sample of medium-resolution Keck/ESI, Magellan/MagE, and VLT/XSHOOTER spectra of 29 quasar pairs at redshift 2 < z < 3. We supplement the sample with additional spectra of 32 pairs from the literature, creating a catalog of 61 quasar pairs with angular separations between 1.″7 and 132.″9 and projected physical separations (r ⊥) between 14 kpc and 887 kpc. We construct a catalog of 906 metal-line absorption doublets of C IV (λλ1548, 1550) with equivalent widths ranging from 6 m Å ≤ W r,1550 ≤ 2053 m Å. The best-fit linear model to the log-space equivalent width frequency distribution ( $\mathrm{log}f({W}_{r})=m\mathrm{log}({W}_{r})+b$ ) of the sample yields coefficients of m = -1.44 ± 0.16 and b = -0.43 ± 0.16. To constrain the projected extent of C IV, we calculate the transverse autocorrelation function. The flattening of the autocorrelation function at low r ⊥ provides a lower limit for the coherence length of the metal enriched CGM-on the order of 200 h -1 comoving kpc. This physical size constraint allows us to refine our understanding of the metals in the CGM, where the extent of C IV in the CGM depends on gas flows, feedback, timescale of metal injection and mixing, and the mass of the host galaxies.

Keywords: circumgalactic medium; intergalactic medium; quasar absorption line spectroscopy
Reconstructing 3D Magnetic Topology of On-disk Prominence Bubbles from Stereoscopic Observations

Bubbles, the semi-circular voids below quiescent prominences (filaments), have been extensively investigated in the past decade. However, to this point the magnetic nature of bubbles has been unverifiable due to the lack of on-disk photospheric magnetic field observations. Here for the first time, we find and investigate an on-disk prominence bubble around a filament barb on 2019 March 18 based on stereoscopic observations from the New Vacuum Solar Telescope (NVST), Solar Dynamics Observatory (SDO), and Spacecraft-A of the Solar TErrestrial RElations Observatory (STEREO-A). In high-resolution NVST Hα images, this bubble has a sharp arch-like boundary and a projected width of ∼26 Mm. Combining SDO and STEREO-A images, we further reconstruct 3D structure of the bubble boundary, whose maximum height is ∼15.6 Mm. The squashing factor Q map deduced from extrapolated 3D magnetic fields around the bubble depicts a distinct arch-shaped interface with a height of ∼11 Mm, which agrees well with the reconstructed 3D structure of the observed bubble boundary. Under the interface lies a set of magnetic loops, which is rooted on a surrounding photospheric magnetic patch. To be more persuasive, another on-disk bubble on 2019 June 10 is presented as a supplement. According to these results obtained from on-disk bubble observations, we suggest that the bubble boundary corresponds to the interface between the prominence dips (barb) and the underlying magnetic loops rooted nearby. Therefore, it is reasonable to speculate that the bubble can form around a filament barb below which there is a photospheric magnetic patch.

Keywords: solar atmosphere; solar filaments; solar magnetic fields; solar prominences
The Chemistry of Chlorine-bearing Species in the Diffuse Interstellar Medium, and New SOFIA/GREAT Observations of HCl+

We have revisited the chemistry of chlorine-bearing species in the diffuse interstellar medium with new observations of the HCl+ molecular ion and new astrochemical models. Using the GREAT instrument on board SOFIA, we observed the 2Π3/2 J = 5/2 - 3/2 transition of HCl+ near 1444 GHz toward the bright THz continuum source W49N. We detected absorption by diffuse foreground gas unassociated with the background source, and were able to thereby measure the distribution of HCl+ along the sight line. We interpreted the observational data using an updated version of an astrochemical model used previously in a theoretical study of Cl-bearing interstellar molecules. The abundance of HCl+ was found to be almost constant relative to the related H2Cl+ ion, but the observed n(H2Cl+)/n(HCl+) abundance ratio exceeds the predictions of our astrochemical model by an order of magnitude. This discrepancy suggests that the rate of the primary destruction process for H2Cl+, dissociative recombination, has been significantly overestimated. For HCl+, the model predictions can provide a satisfactory fit to the observed column densities along the W49N sight line while simultaneously accounting for the OH+ and H2O+ column densities. * GREAT is a development by the MPI für Radioastronomie and the KOSMA/Universität zu Köln, in cooperation with the MPI für Sonnensystemforschung and the DLR Institut für Planetenforschung.

Keywords: interstellar absorption; diffuse interstellar clouds; interstellar molecules; far infrared astronomy; astrochemistry
Halo Properties and Mass Functions of Groups/Clusters from the DESI Legacy Imaging Surveys DR9

Based on a large group/cluster catalog recently constructed from the DESI Legacy Imaging Surveys DR9 using an extended halo-based group finder, we measure and model the group-galaxy weak-lensing signals for groups/clusters in a few redshift bins within redshift range 0.1 ≤ z < 0.6. Here, the background shear signals are obtained based on the DECaLS survey shape catalog, derived with the FOURIER_QUAD method. We divide the lens samples into five equispaced redshift bins and seven mass bins, which allow us to probe the redshift and mass dependence of the lensing signals, and hence the resulting halo properties. In addition to these sample selections, we also check the signals around different group centers, e.g., the brightest central galaxy, the luminosity-weighted center, and the number-weighted center. We use a lensing model that includes off-centering to describe the lensing signals that we measure for all mass and redshift bins. The results demonstrate that our model predictions for the halo masses, biases, and concentrations are stable and self-consistent among different samples for different group centers. Taking advantage of the very large and complete sample of groups/clusters, as well as the reliable estimations of their halo masses, we provide measurements of the cumulative halo mass functions up to redshift z = 0.6, with a mass precision at 0.03 ~ 0.09 dex.

Keywords: weak gravitational lensing; galaxy clusters; observational cosmology; galaxy dark matter halos
WIYN Open Cluster Study. LXXXI. Caught in the Act? The Peculiar Red Giant NGC 2243-W2135

High-dispersion spectra for giants through turnoff stars in the Li 6708 Å region have been obtained and analyzed in the old, metal-deficient open cluster, NGC 2243. When combined with high-dispersion data from other surveys, the cluster is found to contain a uniquely peculiar star at the luminosity level of the red clump. The giant is the reddest star at its luminosity, exhibits variability at a minimum 0.1 mag level on a timescale of days, is a single-lined, radial-velocity variable, and has $v\sin i$ between 35 and 40 km s-1. In sharp contrast with the majority of the red giant cluster members, the star has a detectable Li abundance, potentially as high or higher than other giants observed to date while at or just below the boundary normally adopted for Li-rich giants. The observed anomalies may be indicators of the underlying process by which the giant has achieved its unusual Li abundance, with a recent mass transfer episode being the most probable within the currently limited constraints.

Keywords: open star clusters
Magnetic Helicity Flux across Solar Active Region Photospheres. II. Association of Hemispheric Sign Preference with Flaring Activity during Solar Cycle 24

In our earlier study (Paper I) of this series, we examined the hemispheric sign preference (HSP) of magnetic helicity flux dH/dt across photospheric surfaces of 4802 samples of 1105 unique active regions (ARs) observed during solar cycle 24. Here, we investigate any association of the HSP, expressed as a degree of compliance, with flaring activity, analyzing the same set of dH/dt estimates as used in Paper I. The AR samples under investigation are assigned to heliographic regions (HRs) defined in the Carrington longitude-latitude plane with a grid spacing of 45° in longitude and 15° in latitude. For AR samples in each of the defined HRs, we calculate the degree of HSP compliance and the average soft X-ray flare index. The strongest flaring activity is found to be in one distinctive HR with an extremely low-HSP compliance of 41% as compared to the mean and standard deviation of 62% and 7%, respectively, over all HRs. This sole HR shows an anti-HSP (i.e., <50%) and includes the highly flare-productive AR NOAA 12673, however this AR is not uniquely responsible for the HR's low HSP. We also find that all HRs with the highest flaring activity are located in the southern hemisphere, and they tend to have lower degrees of HSP compliance. These findings point to the presence of localized regions of the convection zone with enhanced turbulence, imparting a greater magnetic complexity and a higher flaring rate to some rising magnetic flux tubes.

Keywords: solar magnetic fields; solar active region magnetic fields; solar active region velocity fields; solar active regions; solar activity; solar photosphere; astronomy data analysis; solar x-ray flares
Unusual Galactic H II Regions at the Intersection of the Central Molecular Zone and the Far Dust Lane

Sgr E is a massive star formation complex found toward the Galactic center that consists of numerous discrete, compact H II regions. It is located at the intersection between the central molecular zone (CMZ) and the far dust lane of the Galactic bar, similar to "hot spots" seen in external galaxies. Compared with other Galactic star formation complexes, the Sgr E complex is unusual because its H II regions all have similar radio luminosities and angular extents, and they are deficient in ∼10 μm emission from their photodissociation regions (PDRs). Our Green Bank Telescope radio recombination line observations increase the known membership of Sgr E to 19 H II regions. There are 43 additional H II region candidates in the direction of Sgr E, 26 of which are detected for the first time here using MeerKAT 1.28 $\,\mathrm{GHz}$ data. Therefore, the true H II region population of Sgr E may number >60. Using APEX SEDIGISM 13CO $2\to 1$ data we discover a 3.0 × 105 $\,{M}_{\odot }$ molecular cloud associated with Sgr E, but find few molecular or far-infrared concentrations at the locations of the Sgr E H II regions. Comparison with simulations and an analysis of its radio continuum properties indicate that Sgr E formed upstream in the far dust lane of the Galactic bar a few million years ago and will overshoot the CMZ, crashing into the near dust lane. We propose that the unusual infrared properties of the Sgr E H II regions are caused by their orbits about the Galactic center, which have possibly stripped their PDRs.

Keywords: h ii regions; galactic center; interstellar medium; radio continuum emission
Propulsion of Spacecraft to Relativistic Speeds Using Natural Astrophysical Sources

In this paper, we explore from a conceptual standpoint the possibility of using natural astrophysical sources to accelerate spacecraft to relativistic speeds. We focus on light sails and electric sails, which are reliant on momentum transfer from photons and protons, respectively, because these two classes of spacecraft are not required to carry fuel on board. The payload is assumed to be stationed near the astrophysical source, and the sail is subsequently unfolded and activated when the source is functional. By considering a number of astrophysical objects such as massive stars, microquasars, supernovae, pulsar wind nebulae, and active galactic nuclei, we show that terminal speeds approaching the speed of light might be realizable under idealized circumstances provided that sufficiently advanced sail materials and control techniques exist. We also investigate the constraints arising from the sail's material properties, the voyage through the ambient source environment, and the passage through the interstellar medium. While all of these considerations pose significant challenges to spacecraft, our analysis indicates that they are not insurmountable in optimal conditions. Finally, we sketch the implications for carrying out future technosignature searches.

Keywords: astrobiology; space vehicle instruments; high energy astrophysics; interstellar medium; search for extraterrestrial intelligence; technosignatures
Persistent Upflows and Downflows at Active Region Boundaries Observed by SUTRI and AIA

Upflows and downflows at active region (AR) boundaries have been frequently observed with spectroscopic observations at extreme ultraviolet passbands. In this paper, we report the coexistence of upflows and downflows at the AR boundaries with imaging observations from the Solar Upper Transition Region Imager (SUTRI) and the Atmospheric Imaging Assembly (AIA). With their observations from 2022 September 21 to 2022 September 30, we find 17 persistent opposite flows occurring along the AR coronal loops. The upflows are prominent in the AIA 193 Å images with a velocity of 50–200 km s‑1, while the downflows are best seen in the SUTRI 465 Å and AIA 131 Å images with a slower velocity of tens of kilometers per second (characteristic temperatures (log T(K)) for 193, 465, and 131 Å are 6.2, 5.7, and 5.6, respectively). We also analyze the center-to-limb variation of the velocities for both upflows and downflows. The simultaneous observations of downflows and upflows can be explained by the chromosphere–corona mass-cycling process, in which the localized chromospheric plasma is impulsively heated to coronal temperature forming a upflow and then these upflows experience radiative cooling producing a downflow with the previously heated plasma returning to the lower atmosphere. In particular, the persistent downflows seen by SUTRI provide strong evidence of the cooling process in the mass cycle. For upflows associated with open loops, part of the plasma is able to escape outward and into the heliosphere as solar wind.

Keywords: solar chromosphere; solar transition region; solar corona; solar ultraviolet emission
Suppression of Star Formation in Galaxy Pairs

We investigate the suppression of star formation in galaxy pairs based on the isolated galaxy pair sample derived from the Sloan Digital Sky Survey survey. By comparing the star formation rate between late-type galaxies (LTGs) in galaxy pairs and those in the isolated environment, we detect a signal of the suppression of star formation in galaxy pairs at d p < 100 kpc and 200 kpc < d p < 350 kpc. The occurrence of the suppression of star formation in these LTGs requires their companion galaxies to have an early-type morphology (n s > 2.5). The suppression of star formation in wide galaxy pairs at 200 kpc < d p < 350 kpc mainly occurs in massive LTGs, while in close galaxy pairs at d p < 100 kpc, it only appears in LTGs with a massive companion ( $\mathrm{log}{M}_{\star }\gt 11.0$ ), nearly independent of their own stellar mass. Based on these findings, we infer that the suppression of star formation in wide galaxy pairs is actually a result of galaxy conformity, while in close galaxy pairs, it stems from the influence of hot circumgalactic medium surrounding companion galaxies.

Keywords: galaxies; galaxy pairs; galaxy interactions