bluuebunny/crossref_metadata_2025_split huggingface dataset:
AFGL 5180 and AFGL 6366S: sites of hub–filament systems at the opposite edges of a filamentary cloud
Authors: Maity A K , Dewangan L K , Bhadari N K , Ojha D K , Chen Z , Pandey Rakesh 
Published: June 2023

ABSTRACT
We present a multiscale and multiwavelength study to unveil massive star formation (MSF) processes around sites AFGL 5180 and AFGL 6366S, both hosting a Class ii 6.7 GHz methanol maser emission. The radio continuum map at 8.46 GHz reveals a small cluster of radio sources towards AFGL 5180. Signatures of the early stages of MSF in our target sites are spatially seen at the opposite edges of a filamentary cloud (length ∼5 pc), which is observed in the submillimetre dust continuum maps. Using the near-infrared photometric data, the spatial distribution of young stellar objects is found towards the entire filament, primarily clustered at its edges. The getsf utility on the Herschel far-infrared images reveals a hub–filament system (HFS) towards each target site. The analysis of the molecular line data, which benefits from large area coverage (∼1° × 1°), detects two cloud components with a connection in both position and velocity space. This supports the scenario of a cloud–cloud collision (CCC) that occurred ∼1 Myr ago. The filamentary cloud, connecting AFGL 5180 and AFGL 6366S, seems spatially close to an H ii region Sh 2−247 excited by a massive O9.5 star. Based on the knowledge of various pressures exerted by the massive star on its surroundings, the impact of its energetic feedback on the filamentary cloud is found to be insignificant. Overall, our observational outcomes favour the possibility of the CCC scenario driving MSF and the formation of HFSs towards the target sites.
A synthetic Roman Space Telescope High-Latitude Time-Domain Survey: supernovae in the deep field
Authors: Wang Kevin X , Scolnic Dan , Troxel M A , Rodney Steven A , Popovic Brodie , Duff Caleb , Filippenko Alexei V , Foley Ryan J , Hounsell Rebekah , Jha Saurabh W , Jones David O , Joshi Bhavin A , Long Heyang , Macias Phillip , Riess Adam G , Rose Benjamin M , Yamamoto Masaya 
Published: June 2023

ABSTRACT
NASA will launch the Nancy Grace Roman Space Telescope (hereafter Roman) in the second half of this decade, which will allow for a generation-defining measurement of dark energy through multiple probes, including Type Ia supernovae (SNe Ia). To improve decisions on survey strategy, we have created the first simulations of realistic Roman images that include artificial SNe Ia injected as point sources in the images. Our analysis combines work done on Roman simulations for weak gravitational lensing studies as well as catalogue-level simulations of SN Ia samples. We have created a time series of images over 2 yr containing ∼1050 SNe Ia, covering a 1 deg2 subarea of a planned 5 deg2 deep survey. We have released these images publicly for community use along with input catalogues of all injected sources. We create secondary products from these images by generating coadded images and demonstrating recovery of transient sources using image subtraction. We perform first-use analyses on these images in order to measure galaxy detection efficiency, point source detection efficiency, and host-galaxy association biases. The simulated images can be found here at https://roman.ipac.caltech.edu/sims/SN_Survey_Image_sim.html.
Machine learning and galaxy morphology: for what purpose?
Authors: Fraix-Burnet D 
Published: June 2023

ABSTRACT
Classification of galaxies is traditionally associated with their morphologies through visual inspection of images. The amount of data to come render this task, inhuman and Machine Learning (mainly Deep Learning) has been called to the rescue for more than a decade. However, the results look mitigate and there seems to be a shift away from the paradigm of the traditional morphological classification of galaxies. In this paper, I want to show that the algorithms indeed are very sensitive to the features present in images, features that do not necessarily correspond to the Hubble or de Vaucouleurs vision of a galaxy. However, this does not preclude to get the correct insights into the physics of galaxies. I have applied a state-of-the-art ‘traditional’ Machine Learning clustering tool, called Fisher-EM, a latent discriminant subspace Gaussian mixture model algorithm to 4458 galaxies carefully classified into 18 types by the EFIGI project. The optimum number of clusters given by the integrated complete likelihood criterion is 47. The correspondence with the EFIGI classification is correct, but it appears that the Fisher-EM algorithm gives a great importance to the distribution of light which translates to characteristics such as the bulge to disc ratio, the inclination or the presence of foreground stars. The discrimination of some physical parameters (bulge-to-total luminosity ratio, (B–V)T, intrinsic diameter, presence of flocculence or dust, and arm strength) is very comparable in the two classifications.
Timing analysis of the new black hole candidate MAXI J1803−298 with Insight–HXMT and NICER
Authors: Zhu Haifan , Chen Xiao , Wang Wei 
Published: June 2023

ABSTRACT
We present the timing analysis results of MAXI J1803−298, a black hole candidate, during its 2021 outburst using data obtained from the Insight–Hard X-ray Modulation Telescope (Insight–HXMT) and the Neutron star Interior Composition Explorer (NICER). Our analysis reveals that the source undergoes a state transition from the low hard state to the hard intermediate state, followed by the soft intermediate state, ultimately reaching the high soft state. We searched for the quasi-periodic oscillations (QPOs) and studied the characteristics of the outburst. At the beginning of the outburst, the source was in the hard state, many type-C QPOs were seen in the Insight–HXMT data, and the frequency of these QPOs increased from ∼0.16 to 2.6 Hz. Our analysis of the rms–frequency relationship of the type-C QPOs indicates a turning point in the frequency. We also analysed the phase lag versus frequency and energy relationship and deduced that the source likely has a high inclination angle, consistent with previous research. The observed rms and phase-lag features in type-C QPOs could be explained by the Lense–Thirring precession model, although alternatives would be still viable. The lag spectrum of type-B QPOs exhibits a U-shaped pattern similar to that of many other sources, and the type-B QPOs’ rms increases as the energy increases. This phenomenon can be explained by the dual-corona model.
Life after AGN switch off: evolution and properties of fossil galactic outflows
Authors: Zubovas Kastytis , Maskeliūnas Gediminas 
Published: June 2023

ABSTRACT
Galaxy-wide outflows driven by active galactic nuclei (AGN) are an important ingredient in galaxy evolution. Analytical calculations suggest that such outflows have significant inertia and can persist long after the AGN itself fades away. We use hydrodynamical simulations of outflows in idealized galaxy bulges to investigate the propagation of these ‘fossil’ AGN outflows. We find that fossil outflows should be common in gas-poor galaxies but form only rarely in gas-rich ones; in general, fossil outflows should outnumber driven ones by a factor of a few in the local Universe, and possibly more at high redshift. When they do form, fossil outflows tend to be lopsided and detached from the nucleus, and colder than their driven counterparts, with a more prominent molecular phase. Spatially resolved and/or multiphase observations can help distinguish fossil AGN outflows from star formation-driven ones, which have similar integrated properties. We discuss a number of spatially-resolved observations of outflows, suggesting that most show evidence of fossil outflow existence, sometimes together with driven outflows on smaller scales.
High-energy cosmic rays and gamma-rays from star clusters: the case of Cygnus OB2
Authors: Blasi Pasquale , Morlino Giovanni 
Published: June 2023

ABSTRACT
We investigate the acceleration of cosmic rays at the termination shock that results from the interaction of the collective wind of star clusters with the surrounding interstellar medium. The solution of the transport equation of accelerated particles in the wind-excavated cavity, including energy losses due to CR interactions with neutral gas in the bubble, shows several interesting properties that are discussed in detail. The issue of the maximum energy of the accelerated particles is discussed with special care, because of its implications for the origin of Galactic cosmic rays. Gamma-ray emission is produced in the cavity due to inelastic pp scattering, while accelerated particles are advected downstream of the termination shock and diffuse at the same time. Both the spectrum and the morphology of such emission are discussed, with a comparison of our results with the observations of gamma-ray emission from the Cygnus OB2 region.
A theoretic analysis of magnetoactive GES-based turbulent solar plasma instability
Authors: Das Souvik , Atteya Ahmed , Karmakar Pralay Kumar 
Published: June 2023

ABSTRACT
A recently reported gravito-electrostatic sheath (GES) model is procedurally applied to study the turbumagnetoactive helioseismic oscillation features in the entire bi-fluidic solar plasma system. The bounded solar interior plasma (SIP, internally self-gravitating), and the unbounded solar wind plasma (SWP, externally point-gravitating) are coupled through the interfacial diffused solar surface boundary (SSB) due to an exact gravito-electrostatic interplay. A numerical platform on the developed theoretic formalism reveals the evolution of both dispersive and non-dispersive features of the modified GES mode fluctuations in new parametric windows. Different colourspectral profiles exhibit important features of the GES-based SIP–SWP perturbations elaborately. It is illustratively shown that the thermostatistical GES stability depends mainly on the radial distance, magnetic field, equilibrium plasma density, and plasma temperature. We see that their dispersive features are more pertinently pronounced in the self-gravitational domains (SIP) than the electrostatic counterparts (SWP). Besides, different characteristic parameters with accelerating (or decelerating) and stabilizing (or destabilizing) effects influencing the entire solar plasma stability are illustratively portrayed. We speculate that, in the SIP, the long-wave (gravitational-like) helioseismic fluctuations become highly dispersive showing more propagatory nature than the shorter ones (acoustic-like). The short waves show more propagatory propensity than the longer ones in the SSB and SWP regime. The reliability of our proposed investigation is bolstered along with the tentative applicability and future scope in light of the current solar observational scenarios, such as SOHO, STEREO, SDO, PSP, and SolO.
Application of the binary spectral model to high-resolution spectra. First estimation of the fundamental parameters for HD 20784
Authors: Kovalev Mikhail , Straumit Ilya 
Published: June 2023

ABSTRACT
In this paper, we applied previously developed method of binary spectral model fitting to the high-resolution spectra of HD 20784. Simultaneously analysing all three available epochs, we found spectroscopic parameters for both components of the system. These parameters are consistent with stellar evolution model’s predictions and analysis of the photometrical data from Transiting Exoplanets Survey Satellite (TESS).
NuSTAR investigation of X-ray variability and hard X-ray spectral properties in IGR J16320-4751 and IGR J16479-4514
Authors: Bahal Varun , Raman Gayathri 
Published: June 2023

Abstract
We present the results obtained from a comprehensive timing and spectral study of two high mass X-ray binary sources using NuSTAR observations. These two sources, IGR J16320-4751 and IGR J16479-4514 were discovered by INTEGRAL and have been characterizated for the first time in the hard X-ray band (beyond 10 keV) in this work. In these sources, we observe the occurrence of intense X-ray flares, with average luminosities exceeding 1036 erg s−1. Our analysis reveals that these flares can be described consistently in the quasi-spherical accretion regime. The orbital phase of the first flare in NuSTAR observation of IGR J16479-4514 matches with the orbital phases of previous flares (φ = 0.35) in this source detected by other telescopes. We conclude that this flare occurs as a result of the periastron passage of the neutron star, rather than due to the presence of a corotating interaction region (CIR). Furthermore, from the energy-resolved pulse profile analysis of IGR J16320-4751, we find that the pulse fraction is lower in hard X-rays compared to the soft X-rays. We present the hard X-ray spectral parameters of these two sources using several standard spectral model components. We do not detect a cyclotron absorption feature in either target. We provide estimates to the surface magnetic field strength of NS in IGR J16320-4751 using two indirect methods. Lastly, we observe spectral hardening during flaring segments compared to the off-flaring segments which indicates that comptonization is more effective during the flaring segments.
A matched-filter approach to radio variability and transients: searching for orphan afterglows in the VAST Pilot Survey
Authors: Leung James K , Murphy Tara , Lenc Emil , Edwards Philip G , Ghirlanda Giancarlo , Kaplan David L , O’Brien Andrew , Wang Ziteng 
Published: June 2023

ABSTRACT
Radio transient searches using traditional variability metrics struggle to recover sources whose evolution time-scale is significantly longer than the survey cadence. Motivated by the recent observations of slowly evolving radio afterglows at gigahertz frequency, we present the results of a search for radio variables and transients using an alternative matched-filter approach. We designed our matched-filter to recover sources with radio light curves that have a high-significance fit to power-law and smoothly broken power-law functions; light curves following these functions are characteristic of synchrotron transients, including ‘orphan’ gamma-ray burst afterglows, which were the primary targets of our search. Applying this matched-filter approach to data from Variables and Slow Transients Pilot Survey conducted using the Australian SKA Pathfinder, we produced five candidates in our search. Subsequent Australia Telescope Compact Array observations and analysis revealed that: one is likely a synchrotron transient; one is likely a flaring active galactic nucleus, exhibiting a flat-to-steep spectral transition over 4 months; one is associated with a starburst galaxy, with the radio emission originating from either star formation or an underlying slowly evolving transient; and the remaining two are likely extrinsic variables caused by interstellar scintillation. The synchrotron transient, VAST J175036.1–181454, has a multifrequency light curve, peak spectral luminosity, and volumetric rate that is consistent with both an off-axis afterglow and an off-axis tidal disruption event; interpreted as an off-axis afterglow would imply an average inverse beaming factor $\langle f^{-1}_{\text{b}} \rangle = 860^{+1980}_{-710}$, or equivalently, an average jet opening angle of $\langle \theta _{\textrm {j}} \rangle = 3^{+4}_{-1}\,$ deg.
Carbon-enhanced metal-poor star candidates from BP/RP spectra in Gaia DR3
Authors: Lucey Madeline , Al Kharusi Nariman , Hawkins Keith , Ting Yuan-Sen , Ramachandra Nesar , Price-Whelan Adrian M , Beers Timothy C , Lee Young Sun , Yoon Jinmi 
Published: June 2023

ABSTRACT
Carbon-enhanced metal-poor (CEMP) stars comprise almost a third of stars with [Fe/H] &lt; −2, although their origins are still poorly understood. It is highly likely that one sub-class (CEMP-s stars) is tied to mass-transfer events in binary stars, while another sub-class (CEMP-no stars) are enriched by the nucleosynthetic yields of the first generations of stars. Previous studies of CEMP stars have primarily concentrated on the Galactic halo, but more recently they have also been detected in the thick disc and bulge components of the Milky Way. Gaia DR3 has provided an unprecedented sample of over 200 million low-resolution (R ≈ 50) spectra from the BP and RP photometers. Training on the CEMP catalogue from the SDSS/SEGUE database, we use XGBoost to identify the largest all-sky sample of CEMP candidate stars to date. In total, we find 58 872 CEMP star candidates, with an estimated contamination rate of 12 per cent. When comparing to literature high-resolution catalogues, we positively identify 60–68 per cent of the CEMP stars in the data, validating our results and indicating a high completeness rate. Our final catalogue of CEMP candidates spans from the inner to outer Milky Way, with distances as close as r ∼ 0.8 kpc from the Galactic centre, and as far as r &gt; 30 kpc. Future higher resolution spectroscopic follow-up of these candidates will provide validations of their classification and enable investigations of the frequency of CEMP-s and CEMP-no stars throughout the Galaxy, to further constrain the nature of their progenitors.
Hierarchical triple mergers: testing Hawking’s area theorem with the inspiral signals
Authors: Tang Shao-Peng , Fan Yi-Zhong , Wei Da-Ming 
Published: June 2023

ABSTRACT
Hawking’s area theorem is one of the fundamental laws of black holes (BHs), which has been tested at a confidence level of $\sim 95~{{\ \rm per\ cent}}$ with gravitational wave (GW) observations by analysing the inspiral and ringdown portions of GW signals, independently. In this work, we propose to carry out the test in a new way with the hierarchical triple merger (i.e. two successive BH mergers occurred sequentially within the observation window of GW detectors), for which the properties of the progenitor BHs and the remnant BH of the first coalescence can be inferred from the inspiral portions of the two mergers. As revealed in our simulations, the BH area law can be well confirmed for some plausible hierarchical triple merger events detectable in LIGO/Virgo/KAGRA/LIGO-India’s O4/O5 runs. Our proposed method provides significant facilitation for testing the area law and complements previous methods.
A T-Dwarf candidate from JWST early release NIRCam data
Authors: Wang Po-Ya , Goto Tomotsugu , Ho Simon C-C , Lin Yu-Wei , Wu Cossas K-W , Ling Chih-Teng , Hashimoto Tetsuya , Kim Seong Jin , Hsiao Tiger Y-Y 
Published: June 2023

Abstract
We present a distant T-type brown dwarf candidate at ≈2.55 kpc discovered in the Cosmic Evolution Early Release Science (CEERS) fields by James Webb Space Telescope (JWST) NIRCam. In addition to the superb sensitivity, we utilised 7 filters from JWST in near-IR and thus is advantageous in finding faint, previously unseen brown dwarfs. From the model spectra in new JWST/NIRCam filter wavelengths, the selection criteria of F115W-F277W&lt;-0.8 and F277W-F444W&gt;1.1 were chosen to target the spectrum features of brown dwarfs having temperatures from 500 K to 1300 K. Searching through the data from Early Release Observations (ERO) and Early Release Science (ERS), we find 1 promising candidate in the CEERS field. The result of SED fitting suggested an early T spectral type with a low effective temperature of Teff ≈1300 K, the surface gravity of log g ≈ 5.25 cms−2, and an eddy diffusion parameter of logKzz ≈ 7 cm2s−1, which indicates an age of ≈1.8 Gyr and a mass of ≈0.05 M⊙. In contrast to typically found T dwarf within several hundred parsecs, the estimated distance of the source is ≈2.55 kpc, showing the JWST’s power to extend the search to a much larger distance.
Suppression of the inclination instability in the trans-Neptunian Solar system
Authors: Das Arnav , Batygin Konstantin 
Published: June 2023

ABSTRACT
The trans-Neptunian scattered disc exhibits unexpected dynamical structure, ranging from an extended dispersion of perihelion distance to a clustered distribution in orbital angles. Self-gravitational modulation of the scattered disc has been suggested in the literature as an alternative mechanism to Planet nine for sculpting the orbital architecture of the trans-Neptunian region. The numerics of this hypothesis have hitherto been limited to N &lt; O(103) superparticle simulations that omit direct gravitational perturbations from the giant planets and instead model them as an orbit-averaged (quadrupolar) potential, through an enhanced J2 moment of the central body. For sufficiently massive discs, such simulations reveal the onset of collective dynamical behaviour – termed the ‘inclination instability’ – wherein orbital circularisation occurs at the expense of coherent excitation of the inclination. Here, we report N = O(104) GPU-accelerated simulations of a self-gravitating scattered disc (across a range of disc masses spanning 5–40 M⊕) that self-consistently account for intraparticle interactions as well as Neptune’s perturbations. Our numerical experiments show that even under the most favourable conditions, the inclination instability never ensues. Instead, due to scattering, the disc depletes. While our calculations show that a transient lopsided structure can emerge within the first few hundreds of Myr, the terminal outcomes of these calculations systematically reveal a scattered disc that is free of any orbital clustering. We conclude thus that the inclination instability mechanism is an inadequate explanation of the observed architecture of the Solar system.
The 3D kinematics of stellar substructures in the periphery of the Large Magellanic Cloud
Authors: Navarrete Camila , Aguado David S , Belokurov Vasily , Erkal Denis , Deason Alis , Cullinane Lara , Carballo-Bello Julio 
Published: June 2023

ABSTRACT
We report the 3D kinematics of 27 Mira-like stars in the northern, eastern, and southern periphery of the Large Magellanic Cloud (LMC), based on Gaia proper motions and a dedicated spectroscopic follow-up. Low-resolution spectra were obtained for more than 40 Mira-like candidates, selected to trace known substructures in the LMC periphery. Radial velocities and stellar parameters were derived for all stars. Gaia data release 3 astrometry and photometry were used to discard outliers, derive periods for those stars with available light curves, and determine their photometric chemical types. The 3D motion of the stars in the reference frame of the LMC revealed that most of the stars, in all directions, have velocities consistent with being part of the LMC disc population, out of equilibrium in the radial and vertical directions. A suite of numerical simulations was used to constrain the most likely past interaction history between the Clouds given the phase-space distribution of our targets. Model realizations in which the Small Magellanic Cloud (SMC) had three pericentric passages around the LMC best resemble the observations. The interaction history of those model realizations has a recent SMC pericentric passage (∼320 Myr ago), preceded by an SMC crossing of the LMC disc at ∼0.97 Gyr ago, having a radial crossing distance of only ∼4.5 kpc. The previous disc crossing of the SMC was found to occur at ∼1.78 Gyr ago, with a similar radial crossing distance of ∼5.6 kpc.