bluuebunny/crossref_metadata_2025_split huggingface dataset:
UV-photoprocessing of acetic acid (CH3COOH)-bearing interstellar ice analogues
Authors: Olivares C del Burgo , Carrascosa H , Escribano B , Caro G M Muñoz , Martín-Doménech R 
Published: December 2023

ABSTRACT
Acetic acid (CH3COOH) was detected in the gas towards interstellar clouds, hot cores, protostars, and comets. Its formation in ice mantles was proposed, and acetic acid awaits detection in the infrared spectra of the ice as most of the other complex organic molecules except methanol. The thermal annealing and UV-irradiation of acetic acid in the ice was simulated experimentally in this work under astrophysically relevant conditions. The experiments were performed under ultrahigh vacuum conditions. An ice layer was formed by vapour deposition onto a cold substrate, and was warmed up or exposed to ultraviolet (UV) photons. The ice was monitored by infrared spectroscopy, while the molecules desorbing to the gas phase were measured using a quadrupole mass spectrometer. The transformation of the CH3COOH monomers to cyclic dimers occurs at 120 K, and the crystal form composed of chain polymers was observed above 160 K during warm-up of the ice. Ice sublimation proceeds at 189 K in our experiments. Upon UV-irradiation, simpler species and radicals are formed, which leads to a residue made of complex molecules after warm-up to the room temperature. The possible formation of oxalic acid needs to be confirmed. The photodestruction of acetic acid molecules is reduced when mixed with water in the ice. This work may serve to search for the acetic acid photoproducts in lines of sight where this species is detected. A comparison of the reported laboratory infrared spectra with current JWST observations allows to detect or set upper limits on the CH3COOH abundances in interstellar and circumstellar ice mantles.
A multiwavelength study of spiral structure in galaxies. II. Spiral arms in deep optical observations
Authors: Mosenkov Aleksandr V , Panasyuk Andrey D , Turner Savanah , Bartier Crystal-Lynn , Skryabina Maria N , Marchuk Alexander A , Savchenko Sergey S , Bergstedt Jakob , Reshetnikov Vladimir P , Chugunov Ilia V 
Published: December 2023

ABSTRACT
In this paper, we look to analyse the spiral features of grand-design, multiarmed, and flocculent spiral galaxies using deep optical imaging from DESI Legacy Imaging Surveys. We explore the resulting distributions of various characteristics of spiral structure beyond the optical radius, such as the distributions of azimuthal angle, the extent of spiral arms, and of the spiral arm widths for the aforementioned galaxy classes. We also compare the measured properties for isolated galaxies and galaxies in groups and clusters. We find that, on average, compared to multiarmed and flocculent spiral galaxies, the spiral arms of grand-design galaxies exhibit slightly larger azimuthal angles, greater extent, and larger widths in the periphery of the galaxy. Furthermore, on average, isolated galaxies tend to have slightly smaller widths of outer spiral arms compared to galaxies in tight environments, which is likely related to the tidally induced mechanism for generating wider outer spiral arms. We also report that breaks of the disc surface brightness profiles are often related to the truncation of spiral arms in galaxies.
The VISCACHA survey – IX. The SMC Southern Bridge in 8D
Authors: Parisi M C , Oliveira R A P , Angelo M S , Dias B , Maia F F S , Saroon S , Feinstein C , Santos J F C , Bica E , Ferreira B Pereira Lima , Fernández−Trincado J G , Westera P , Minniti D , Garro E R , Santrich O J Katime , De Bortoli B J , Souza S O , Kerber L , Pérez−Villegas A 
Published: December 2023

ABSTRACT
The structure of the Small Magellanic Cloud (SMC) outside of its main body is characterized by tidal branches resulting from its interactions mainly with the Large Magellanic Cloud (LMC). Characterizing the stellar populations in these tidal components helps to understand the dynamical history of this galaxy and of the Magellanic system in general. We provide full phase-space vector information for Southern Bridge clusters. We performed a photometric and spectroscopic analysis of twelve SMC clusters, doubling the number of SMC clusters with full phase-space vector information known to date. We reclassify the sample considering 3D distances and 3D velocities. We found that some of the clusters classified as Southern Bridge objects according to the projected 2D classification actually belong to the Main Body and Counter-Bridge in the background. The comparison of the kinematics of the genuine foreground Bridge clusters with those previously analysed in the same way reveals that Southern Bridge clusters are moving towards the LMC and share the kinematics of the Northern Bridge. Adding to our sample clusters from the literature with CaT metallicity determinations we compare the age–metallicity relation of the Southern Bridge with the one of the Northern Bridge. We reinforce the idea that both regions do not seem to have experienced the same chemical enrichment history and that there is a clear absence of clusters in the Northern Bridge older than 3 Gyr and more metal poor than −1.1, which would not seem to be due to a selection effect.
The narrow-line region properties of ESO 138-G001 unveiled by SOAR/SIFS observations
Authors: Rodríguez-Ardila A , May D , Panda S , Fonseca-Faria M A , Fraga L 
Published: December 2023

ABSTRACT
We study in detail the inner ∼600 pc of the Seyfert 2 galaxy ESO 138-G001 by means of the Soar Integral Field Spectrograph attached to the SOAR telescope. This source is known for displaying a very rich coronal line spectrum and a blob of high-excitation emission ∼3 arcsec south-east (SE) of the active galactic nucleus (AGN). The nature of this emission has not been fully understood yet. The excellent spatial and spectral resolution of SIFS allows us to confirm that the bulk of the coronal line forest emission region is very compact, of ∼0.8 arcsec in diameter, centred on the AGN and most likely powered by radiation from the AGN. In addition, evidence of a nuclear outflow, restricted to the inner 1 arcsec centred at the nucleus is found based on the detection of broad components in the most important emission lines. The gas in the inner few tens of parsecs filters out the AGN continuum so that the NLR is basically illuminated by a modified SED. This scenario is confirmed by means of photoionization models that reproduce the most important lines detected in the SIFS field of view. From the modelling, we also found that the black hole mass MBH of the AGN is about 105.50 M⊙, in agreement with previous X-ray observations. The spectrum of the SE blob is dominated by emission lines of low- to mid-ionization, with no hints of coronal lines. Our results show that it represents gas in the ionization cone that is photoionized by the filtered central AGN continuum.
Research of the family associations of active asteroids in the main belt
Authors: Xin Yingqi , Shi Jianchun , Ma Yuehua 
Published: December 2023

ABSTRACT
We apply the Hierarchical Clustering method (HCM) and Selective Backward Integration method (BIM) to search for associated families and young families for all main-belt active asteroids (MBAAs) known to date. We find four newly candidate sub-groups of known families, which include the candidate Brueghel family associated with 176P/LINEAR, the candidate 324P group associated with 324P/La Sagra, the candidate G1 group associated with P/2016 G1, and the candidate Tutenchamun family associated with (62412) 2000 SY178. Additionally, we identify three entirely new candidate families, the Interamnia family associated with P/2021 A5, the candidate 457P group associated with 457P/Lemmon-PANSTARRS, and the candidate Scheila family associated with (596) Scheila. We also reveal two newly identified family associations with known families between 259P/Garradd and the Adeona family, P/2019 A4 and the Jones family. All main-belt comets (MBCs) are likely associated with young and primitive families. Some unstable MBCs, which cannot be identified using HCM, may still originate from young and primitive families. However, due to dynamic diffusion, they cannot be conclusively linked to current families. Impact-disrupted asteroids could be linked with young families and they may change their original spectrum under the impact activity. Rotational fission of young and primitive asteroids might be a useful mechanism for facilitating the exposure of subsurface ice, and therefore triggering sublimation-driven activity. Rapid rotation and sublimation activity mechanisms are likely coupled. Therefore, further research should be made on such fast rotational asteroids that are located in primitive families.
Insights into the phase-dependent cyclotron line feature in XTE J1946+274: an AstroSat and Insight-HXMT view
Authors: Devaraj Ashwin , Sharma Rahul , Nagesh Shwetha , Paul Biswajit 
Published: December 2023

ABSTRACT
XTE J1946+274 is a Be/X-ray binary with a 15.8 s spin period and 172 d orbital period. Using RXTE/PCA data of the 1998 outburst, a cyclotron line around 37 keV was reported. The presence of this line, its dependence on the pulse phase, and its variation with luminosity have been of some debate since. In this work, we present the re-analysis of two AstroSat observations: one made during the rising phase of the 2018 outburst and the other during the declining phase of the 2021 outburst. We also present a new analysis of the Insight-HXMT observations of the source at the peak of the 2018 outburst. We find the source to be spinning up over the course of the outburst and spinning down between the two outbursts. We report the presence of a higher cyclotron line energy using the 2018 AstroSat observation (∼45 keV) and 2018 Insight-HXMT observation (∼50 keV) and a line at ∼40 keV during the declining phase of the 2021 outburst using data from AstroSat. We also investigate the pulse phase dependence of the cyclotron line parameters and find that the line is significantly detected in all the phases of both AstroSat observations, along with showing variation with the pulse phase. This differs from the previous results reported using BeppoSAX and NuSTAR. We explain this behaviour of the cyclotron line to be due to photon spawning and different accretion column radii at the two poles of this neutron star.
SPH–DEM modelling of hypervelocity impacts on rubble-pile asteroids
Authors: Jiao Yifei , Yan Xiaoran , Cheng Bin , Baoyin Hexi 
Published: December 2023

ABSTRACT
Investigating the hypervelocity impact process on rubble-pile asteroids is crucial for understanding the formation and evolution of small celestial bodies, and has important implications for planetary defence. In recent years, numerical simulations have been widely used to model asteroid impacts, as a complement to experimental and theoretical approaches. In particular, the hybrid SPH–DEM framework has been introduced to describe the multistage dynamics involving shock propagation and gravitational re-accumulation. However, the tension between modelling accuracy and computational costs poses significant challenges in rubble-pile impact simulations. In this study, we introduce two distinct particle configurations, i.e. multiple layers of similar-sized surface contact particles and a set of different-sized gravity particles, to efficiently describe the large irregular boulders during long-term evolution. Accordingly, the new transition algorithms are implemented to convert the smoothed particle hydrodynamics (SPH) results into the desired discrete-element method (DEM) configurations. With the proposed method, the complexity of contact computation is reduced from $\mathcal {O}(N)$ to $\mathcal {O}(N^{2/3})$, and the gravity computation is accelerated by about one hundred times while maintaining the same level of resolution. The method is then used to simulate the double asteroid redirection test impact on the rubble-pile asteroid Dimorphos. Our numerical simulations have reproduced the observation results regarding momentum transfer and mass ejection. Moreover, we predict that the impact event will form a final crater larger than 45–68 m in diameter and lead to global resurfacing of the target. The renewed surface and fresh interior will be accessible to the upcoming Hera mission, providing new perspectives on the formation and evolution of the rubble-pile binary asteroids.
Doppler imaging of a southern ApSi star HD 152564
Authors: Potravnov I , Ryabchikova T , Piskunov N , Pakhomov Y , Kniazev A 
Published: December 2023

ABSTRACT
We present the results of the spectroscopic study of a chemically peculiar star HD 152564. Using medium-resolution (R = 37 000) observations obtained with the high-resolution fibre échelle spectrograph mounted on the South African Large Telescope, we determined atmospheric parameters Teff = 11 950 ± 200 K and log g = 3.6 ± 0.2 dex. Abundance analysis revealed mild deficiency of the light elements and an overabundance of up to ∼2 dex of metals, with the greatest excess for silicon. With these characteristics, HD 152564 is a typical member of the silicon subgroup of Ap stars. The rotational modulation of the light curve and line profiles of HD 152564 are typical for the inhomogeneous surface distribution of elements in its atmosphere. We performed multi-element Doppler imaging of the surface of HD 152564. Abundance maps constructed for He, O, Mg, Si, and Fe revealed the concentration of these elements in a sequence of equatorial spots as well as in the circumpolar rings. The photometric maximum of the light curve coincided with the visibility of two most overabundant silicon spots. Abundances determined from the different ionization stages of Fe and Si show clear evidence for vertical stratification of these elements in the atmosphere of HD 152564. Meanwhile, the horizontal distribution of silicon reconstructed from the lines of different ionization stages and excitation energies appears to be identical with increasing average abundance deeper in atmosphere.
Not all subhaloes are created equal: modelling the diversity of subhalo density profiles in TNG50
Authors: Heinze Felix M , Despali Giulia , Klessen Ralf S 
Published: December 2023

ABSTRACT
In this work, we analyse the density profiles of subhaloes with masses Msh ≥ 1.4 × 108 M⊙ in the TNG50 simulation, with the aim of including baryonic effects. We evaluate the performance of frequently used models, such as the standard Navarro–Frenk–White (NFW), the Einasto, and a smoothly truncated version of the NFW profile. We find that these models do not perform well for the majority of subhaloes, with the NFW profile giving the worst fit in most cases. This is primarily due to mismatches in the inner and outer logarithmic slopes, which are significantly steeper for a large number of subhaloes in the presence of baryons. To address this issue, we propose new three-parameter models and show that they significantly improve the goodness of fit independently of the subhalo’s specific properties. Our best-performing model is a modified version of the NFW profile with an inner log-slope of −2 and a variable truncation that is sharper and steeper than the slope transition in the standard NFW profile. Additionally, we investigate how both the parameter values of the best density profile model and the average density profiles vary with subhalo mass, Vmax, distance from the host halo centre, baryon content, and infall time, and we also present explicit scaling relations for the mean parameters of the individual profiles. The newly proposed fit and the scaling relations are useful to predict the properties of realistic subhaloes in the mass range 108 M⊙ ≤Msh ≤ 1013 M⊙ that can be influenced by the presence of baryons.
Modelling post-reionization H i distributions in fuzzy dark matter cosmologies using conditional normalizing flows
Authors: Dome Tibor , Azhar Rumail , Fialkov Anastasia 
Published: December 2023

ABSTRACT
Upcoming 21-cm intensity mapping experiments like the Square Kilometer Array (SKA) hold significant potential to constrain the properties of dark matter. In this work, we model neutral hydrogen (H i) distributions using high-resolution hydrodynamical N-body simulations of both cold dark matter (CDM) and fuzzy dark matter (FDM) cosmologies in the post-reionization redshift range of z = 3.42−4.94. We show that the H i abundance decreases in FDM-like cosmologies. Extreme FDM models with m ∼ 10−22 eV are at odds with a range of measurements. Due to the increased halo bias, the H i bias increases, paralleled by the damped Lyman-α (DLA) bias which we infer from the cross-section of DLAs. The distribution of the latter in extreme FDM models has a high median at the low-mass end, which can be traced to the high column density of cosmic filaments. FDM models exhibit a very similar abundance of DLAs compared to CDM while sub-DLAs are already less abundant. We study the prospects of detecting the brightest H i peaks with SKA1-Low at z = 4.94, indicating moderate signal-to-noise ratios (SNRs) at angular resolution θA = 2 arcmin with a rapidly declining SNR for lower values of θA. After training the conditional normalizing flow network HIGlow on 2D H i maps, we interpolate its latent space of axion masses to predict the peak flux for a new, synthetic FDM cosmology, finding good agreement with expectations. This work thus underscores the potential of normalizing flows in capturing complex, non-linear structures within H i maps, offering a versatile tool for conditional sample generation and prediction tasks.
In-situ versus accreted Milky Way globular clusters: a new classification method and implications for cluster formation
Authors: Belokurov Vasily , Kravtsov Andrey 
Published: December 2023

ABSTRACT
We present a new scheme for the classification of the in-situ and accreted globular clusters (GCs). The scheme uses total energy E and z-component of the orbital angular momentum and is calibrated using the [Al/Fe] abundance ratio. We demonstrate that this classification results in two GC populations with distinct spatial, kinematic, and chemical abundance distributions. The in-situ GCs are distributed within the central 10 kpc of the Galaxy in a flattened configuration aligned with the Milky Way (MW) disc, while the accreted GCs have a wide distribution of distances and a spatial distribution close to spherical. In-situ and accreted GCs have different $\rm [Fe/H]$ distributions with the well-known bimodality present only in the metallicity distribution of the in-situ GCs. Furthermore, the accreted and in-situ GCs are well separated in the plane of $\rm [Al/Fe]-[Mg/Fe]$ abundance ratios and follow distinct sequences in the age–$\rm [Fe/H]$ plane. The in-situ GCs in our classification show a clear disc spin-up signature – the increase of median Vϕ at metallicities −1.3 &lt; [Fe/H] &lt; −1 similar to the spin-up in the in-situ field stars. This signature signals the MW’s disc formation, which occurred ≈11.7−12.7 Gyr ago (or at z ≈ 3.1−5.3) according to in-situ GC ages. In-situ GCs with metallicities of $\rm [Fe/H]\gtrsim -1.3$ were thus born in the MW disc, while lower metallicity in-situ GCs were born during early, turbulent, pre-disc stages of the evolution of the Galaxy and are part of its Aurora stellar component.
An Overview of Sunspot Observations in the Early Maunder Minimum: 1645–1659
Authors: Hayakawa Hisashi , Carrasco Víctor M S , Aparicio Alejandro J P , Villalba Álvarez Joaquín , Vaquero José M 
Published: December 2023

Abstract
Within four centuries of sunspot observations, the Maunder Minimum (MM) in 1645–1715 has been considered a unique grand minimum with weak solar cycles in group numbers of sunspots and hemispheric asymmetry in sunspot positions. However, the early part of the MM (1645–1659) is poorly understood in terms of its source records and has accommodated diverse reconstructions of the contemporaneous group number. This study identified their source records, classidied them in three different categories (datable observations, general descriptions, and misinterpreted records), and revised their data. On this basis, we estimated the yearly mean group number using the brightest star method, derived the active day fraction (ADF), reconstructed the sunspot number based on ADF, and compared them with proxy reconstructions from the tree-ring data sets. Our results revised the solar activity in the early MM downward in yearly mean group numbers using the brightest star method and upward in the active day fraction and sunspot number estimates. Our results are consistent with the proxy reconstruction for 1645–1654 and show more realistic values for 1657–1659 (against the unphysical negative sunspot number). These records have paid little attention to sunspot positions, except for Hevelius' report on a sunspot group in the northern solar hemisphere in 1652 April. Therefore, slight caveats are required to discuss if the sunspot positions are located purely in the southern solar hemisphere throughout the MM.
An efficient and robust method to estimate halo concentration based on the method of moments
Authors: Wang Kai , Mo H J , Chen Yangyao , Schaye Joop 
Published: December 2023

ABSTRACT
We propose an efficient and robust method to estimate the halo concentration based on the first moment of the density distribution, which is $R_1\equiv \int _0^{r_{\rm vir}}4\pi r^3\rho (r)\mathrm{ d}r/M_{\rm vir}/r_{\rm vir}$. We find that R1 has a monotonic relation with the concentration parameter of the Navarro–Frenk–White (NFW) profile, and that a cubic polynomial function can fit the relation with an error $\lesssim 3~{{\ \rm per\ cent}}$. Tests on ideal NFW haloes show that the conventional NFW profile fitting method and the Vmax/Vvir method produce biased halo concentration estimation by $\approx 10~{{\ \rm per\ cent}}$ and $\approx 30~{{\ \rm per\ cent}}$, respectively, for haloes with 100 particles. In contrast, the systematic error for our R1 method is smaller than 0.5 per cent even for haloes containing only 100 particles. Convergence tests on realistic haloes in N-body simulations show that the NFW profile fitting method underestimates the concentration parameter for haloes with ≲300 particles by $\gtrsim 20~{{\ \rm per\ cent}}$, while the error for the R1 method is $\lesssim 8~{{\ \rm per\ cent}}$. We also show other applications of R1, including estimating Vmax and the Einasto concentration ce ≡ rvir/r−2. The calculation of R1 is efficient and robust, and we recommend including it as one of the halo properties in halo catalogues of cosmological simulations.