bluuebunny/crossref_metadata_2025_split huggingface dataset:
Near-infrared characterization of ultra-diffuse galaxies in Abell 2744 by JWST/NIRISS imaging
Authors: Ikeda Ryota , Morishita Takahiro , Tsukui Takafumi , Vulcani Benedetta , Trenti Michele , Metha Benjamin , Acebron Ana , Bergamini Pietro , Grillo Claudio , Iono Daisuke , Mercurio Amata , Rosati Piero , Vanzella Eros 
Published: June 2023

ABSTRACT
We present a search and characterization of ultra-diffuse galaxies (UDGs) in the Frontier Fields cluster Abell 2744 at $z$ = 0.308. We use JWST/NIRISS F200W observations, acquired as part of the GLASS-JWST Early Release Science programme, aiming to characterize morphologies of cluster UDGs and their diffuse stellar components. A total number of 22 UDGs are identified by our selection criteria using morphological parameters, down to stellar mass of ∼107 M⊙. The selected UDGs are systematically larger in effective radius in F200W than in Hubble Space Telescope (HST)/ACS F814W images, which implies that some of them would not have been identified as UDGs when selected at rest-frame optical wavelengths. In fact, we find that about one-third of the UDGs were not previously identified based on the F814W data. We observe a flat distribution of the UDGs in the stellar mass–size plane, similar to what is found for cluster quiescent galaxies at comparable mass. Our pilot study using the new JWST F200W filter showcases the efficiency of searching UDGs at cosmological distances, with 1/30 of the exposure time of the previous deep observing campaign with HST. Further studies with JWST focusing on spatially resolved properties of individual sources will provide insight into their origin.
A GALEX view of the DA white dwarf population
Authors: Wall Renae E , Kilic Mukremin , Bergeron P , Leiphart Nathan D 
Published: June 2023

ABSTRACT
We present a detailed model atmosphere analysis of 14001 DA white dwarfs from the Montreal White Dwarf Database with ultraviolet photometry from the GALEX mission. We use the 100 pc sample, where the extinction is negligible, to demonstrate that there are no major systematic differences between the best-fitting parameters derived from optical only data and the optical + UV photometry. GALEX FUV and NUV data improve the statistical errors in the model fits, especially for the hotter white dwarfs with spectral energy distributions that peak in the UV. Fitting the UV to optical spectral energy distributions also reveals UV-excess or UV-deficit objects. We use two different methods to identify outliers in our model fits. Known outliers include objects with unusual atmospheric compositions, strongly magnetic white dwarfs, and binary white dwarfs, including double degenerates and white dwarf + main-sequence systems. We present a list of 89 newly identified outliers based on GALEX UV data; follow-up observations of these objects will be required to constrain their nature. Several current and upcoming large-scale spectroscopic surveys are targeting &gt;105 white dwarfs. In addition, the ULTRASAT mission is planning an all-sky survey in the NUV band. A combination of the UV data from GALEX and ULTRASAT and optical data on these large samples of spectroscopically confirmed DA white dwarfs will provide an excellent opportunity to identify unusual white dwarfs in the solar neighbourhood.
GRB 201015A and the nature of low-luminosity soft gamma-ray bursts
Authors: Patel M , Gompertz B P , O’Brien P T , Lamb G P , Starling R L C , Evans P A , Amati L , Levan A J , Nicholl M , Ackley K , Dyer M J , Lyman J , Ulaczyk K , Steeghs D , Galloway D K , Dhillon V S , Ramsay G , Noysena K , Kotak R , Breton R P , Nuttall L K , Pallé E , Pollacco D 
Published: June 2023

ABSTRACT
GRB 201015A is a peculiarly low luminosity, spectrally soft gamma-ray burst (GRB), with T90 = 9.8 ± 3.5 s (time interval of detection of 90 per cent of photons from the GRB), and an associated supernova (likely to be type Ic or Ic-BL). GRB 201015A has an isotropic energy $E_{\gamma , \rm iso}$$= 1.75 ^{+0.60} _{-0.53} \times 10^{50}$ erg, and photon index $\Gamma = 3.00 ^{+0.50} _{-0.42}$ (15–150 keV). It follows the Amati relation, a correlation between $E_{\gamma , \rm iso}$ and spectral peak energy Ep followed by long GRBs. It appears exceptionally soft based on Γ, the hardness ratio of HR = 0.47 ± 0.24, and low-Ep, so we have compared it to other GRBs sharing these properties. These events can be explained by shock breakout, poorly collimated jets, and off-axis viewing. Follow-up observations of the afterglow taken in the X-ray, optical, and radio reveal a surprisingly late flattening in the X-ray from t = (2.61 ± 1.27) × 104 s to $t = 1.67 ^{+1.14} _{-0.65} \times 10^6$ s. We fit the data to closure relations describing the synchrotron emission, finding the electron spectral index to be $p = 2.42 ^{+0.44} _{-0.30}$ and evidence of late-time energy injection with coefficient $q = 0.24 ^{+0.24} _{-0.18}$. The jet half opening angle lower limit (θj ≥ 16°) is inferred from the non-detection of a jet break. The launch of SVOM and Einstein Probe in 2023 should enable detection of more low-luminosity events like this, providing a fuller picture of the variety of GRBs.
Universal gravothermal evolution of isolated self-interacting dark matter halos for velocity-dependent cross-sections
Authors: Outmezguine Nadav Joseph , Boddy Kimberly K , Gad-Nasr Sophia , Kaplinghat Manoj , Sagunski Laura 
Published: June 2023

ABSTRACT
We study the evolution of isolated self-interacting dark matter halos using spherically symmetric gravothermal equations allowing for the scattering cross-section to be velocity dependent. We focus our attention on the large class of models where the core is in the long mean free path regime for a substantial time. We find that the temporal evolution exhibits an approximate universality that allows velocity-dependent models to be mapped onto velocity-independent models in a well-defined way using the scattering time-scale computed when the halo achieves its minimum central density. We show how this time-scale depends on the halo parameters and an average cross-section computed at the central velocity dispersion when the central density is minimum. The predicted collapse time is fully defined by the scattering time-scale, with negligible variation due to the velocity dependence of the cross-section. We derive new self-similar solutions that provide an analytic understanding of the numerical results.
Coronal height constraint in IRAS 13224–3809 and 1H 0707–495 by the random forest regressor
Authors: Mankatwit N , Chainakun P , Luangtip W , Young A J 
Published: June 2023

ABSTRACT
We develop a random forest regressor (RFR) machine learning model to trace the coronal evolution in two highly variable active galactic nuclei (AGNs) IRAS 13224-3809 and 1H 0707-495 observed with XMM–Newton, by probing the X-ray reverberation features imprinted on their power spectral density (PSD) profiles. Simulated PSDs in the form of a power law, with a similar frequency range and bins to the observed data, are produced. Then, they are convolved with relativistic disc-response functions from a lamp-post source before being used to train and test the model to predict the coronal height. We remove some bins that are dominated by Poisson noise and find that the model can tolerate the frequency-bin removal up to ∼10 bins to maintain a prediction accuracy of R2 &gt; 0.9. The black hole mass and inclination should be fixed so that the accuracy in predicting the source height is still &gt;0.9. The accuracy also increases with the reflection fraction. The corona heights for both AGN are then predicted using the RFR model developed from the simulated PSDs, whose frequency range and bins are specifically adjusted to match those from each individual observation. The model suggests that their corona varies between ∼5–18 rg, with R2 &gt; 0.9 for all observations. Such high accuracy can still be obtained if the difference between the true mass and the trained value is ${\lesssim}10\ \hbox{per cent}$. Finally, the model supports the height-changing corona under the light-bending scenario, where the height is correlated to source luminosity in both IRAS 13224-3809 and 1H 0707-495.
Effective temperatures of classical Cepheids from line-depth ratios in the H-band
Authors: Kovtyukh V , Lemasle B , Nardetto N , Bono G , da Silva R , Matsunaga N , Yushchenko A , Fukue K , Grebel E K 
Published: June 2023

ABSTRACT
The technique of line depth ratios (LDRs) is one of the methods to determine the effective temperature of a star. They are crucial in the spectroscopic studies of variable stars like Cepheids since no simultaneous photometry is usually available. A good number of LDR-temperature relations are already available in the optical domain; here we want to expand the number of relations available in the near-infrared (NIR) in order to fully exploit the capabilities of current and upcoming NIR spectrographs. We used 115 simultaneous spectroscopic observations in the optical and the NIR for six Cepheids and optical LDRs to find new pairs of lines sensitive to temperature and to calibrate LDR-temperature relations in the NIR spectral range. We have derived 87 temperature calibrations valid in the [4800–6500] K range of temperatures. The typical uncertainty for a given relation is 60–70 K, and combining many of them provides a final precision within 30–50 K. We found a discrepancy between temperatures derived from optical or NIR LDR for pulsations phases close to ϕ ≈0.0 and we discuss the possible causes for these differences. LDRs in the NIR will allow us to spectroscopically investigate highly reddened Cepheids in the Galactic centre or in the far side of the disc.
Impact of quasi-periodic and steep-spectrum timing noise on the measurement of pulsar timing parameters
Authors: Keith Michael J , Niţu Iuliana C 
Published: June 2023

Abstract
Timing noise in pulsars is often modelled with a Fourier-basis Gaussian process that follows a power law with periodic boundary conditions on the observation time, Tspan. However the actual noise processes can extend well below 1/Tspan, and many pulsars are known to exhibit quasi-periodic timing noise. In this paper we investigate several adaptions that try to account for these differences between the observed behaviour and the simple power-law model. Firstly, we propose to include an additional term that models the quasi-periodic spin-down variations known to be present in many pulsars. Secondly, we show that a Fourier basis of 1/2Tspan can be more suited for estimating long term timing parameters such as the spin frequency second derivative (F2), and is required when the exponent of the power spectrum is greater than ∼4. We also implement a Bayesian version of the generalised least squares ‘Cholesky’ method which has different limitations at low frequency, but find that there is little advantage over Fourier-basis methods. We apply our quasi-periodic spin down model to a sample of pulsars with known spin-down variations and show that this improves parameter estimation of F2 and proper motion for the most pathological cases, but in general the results are consistent with a power-law model. The models are all made available through the run_enterprise software package.
Dynamically coupled kinetic chemistry in brown dwarf atmospheres – I. Performing global scale kinetic modelling
Authors: Lee Elspeth K H , Tan Xianyu , Tsai Shang-Min 
Published: June 2023

ABSTRACT
The atmospheres of brown dwarfs have been long observed to exhibit a multitude of non-equilibrium chemical signatures and spectral variability across the L, T, and Y spectral types. We aim to investigate the link between the large-scale 3D atmospheric dynamics and time-dependent chemistry in the brown dwarf regime, and to assess its impact on spectral variability. We couple the miniature kinetic chemistry module ‘mini-chem’ to the Exo-FMS general circulation model (GCM). We then perform a series of idealized brown dwarf regime atmospheric models to investigate the dynamical 3D chemical structures produced by our simulations. The GCM output is post-processed using a 3D radiative transfer model to investigate hemisphere-dependent spectral signatures and rotational variability. Our results show the expected strong non-equilibrium chemical behaviour brought on by vertical mixing and global spatial variations due to zonal flows. Chemical species are generally globally homogenized, showing variations of ±10 per cent or less, dependent on pressure level, and follow the dynamical structures present in the atmosphere. However, we find localized storm regions and eddies can show higher contrasts, up to ±100 per cent, in mixing ratio compared to the background global mean. This initial study represents another step in understanding the connection between 3D atmospheric flows in brown dwarfs and their rich chemical inventories.
Astrophysical cloaking of a naked singularity
Authors: Vieira Ronaldo S S , Kluźniak Włodek 
Published: June 2023

Abstract
A massive naked singularity would be cloaked by accreted matter, and thus may appear to a distant observer as an opaque (quasi-)spherical surface of a fluid, not unlike that of a star or planet. We present here analytical solutions for levitating atmospheres around a wide class of spherically symmetric naked singularities. Such an atmosphere can be constructed in every spacetime which possesses a zero-gravity radius and which is a solution of a (modified-)gravity theory possessing the usual conservation laws for matter. Its density peaks at the zero-gravity radius and the atmospheric fluid is supported against infall onto the singularity by gravity alone. In an astrophysical context, an opaque atmosphere would be formed in a very short time by accretion of ambient matter onto the singularity—in a millisecond for an X-ray binary, in a thousand seconds for a singularity traversing interstellar space, and a thousand years for a singularity that is the central engine of an AGN.
Carbon–oxygen ultra-massive white dwarfs in general relativity
Authors: Althaus Leandro G , Córsico Alejandro H , Camisassa María E , Torres Santiago , Gil-Pons Pilar , Rebassa-Mansergas Alberto , Raddi Roberto 
Published: June 2023

ABSTRACT
We employ the La Plata stellar evolution code, lpcode, to compute the first set of constant rest-mass carbon–oxygen ultra-massive white dwarf evolutionary sequences for masses higher than 1.29 M⊙ that fully take into account the effects of general relativity on their structural and evolutionary properties. In addition, we employ the lp-pul pulsation code to compute adiabatic g-mode Newtonian pulsations on our fully relativistic equilibrium white dwarf models. We find that carbon–oxygen white dwarfs more massive than 1.382 M⊙ become gravitationally unstable with respect to general relativity effects, being this limit higher than the 1.369 M⊙ we found for oxygen–neon white dwarfs. As the stellar mass approaches the limiting mass value, the stellar radius becomes substantially smaller compared with the Newtonian models. Also, the thermo-mechanical and evolutionary properties of the most massive white dwarfs are strongly affected by general relativity effects. We also provide magnitudes for our cooling sequences in different passbands. Finally, we explore for the first time the pulsational properties of relativistic ultra-massive white dwarfs and find that the period spacings and oscillation kinetic energies are strongly affected in the case of most massive white dwarfs. We conclude that the general relativity effects should be taken into account for an accurate assessment of the structural, evolutionary, and pulsational properties of white dwarfs with masses above ∼1.30 M⊙.
CN and CO features: key indicators of red giant evolutionary phase in moderate-resolution X-shooter spectra
Authors: Banks Kirsten A , Ho Chantel Y Y , Martell Sarah L , Buder Sven , Stello Dennis , Sharma Sanjib , Priest James , Gonneau Anaïs , Hawkins Keith 
Published: June 2023

ABSTRACT
Data-driven analysis methods can help to infer physical properties of red giant stars where ‘gold-standard’ asteroseismic data are not available. The study of optical and infrared spectra of red giant stars with data-driven analyses has revealed that differences in oscillation frequencies and their separations are imprinted in said spectra. This makes it possible to confidently differentiate core helium burning red clump (RC) stars from those that are still on their first ascent of the red giant branch (RGB). We extend these studies to a tenfold larger wavelength range of 0.33–2.5 µm with the moderate-resolution VLT/X-shooter spectrograph. Our analysis of 49 stars with asteroseismic data from the K2 mission confirms that CN, CO, and CH features are indeed the primary carriers of spectroscopic information on the evolutionary stages of red giant stars. We report 215 informative features for differentiating the RC from the RGB within the range of 0.33–2.5 µm. This makes it possible for existing and future spectroscopic surveys to optimize their wavelength regions to deliver both a large variety of elemental abundances and reliable age estimates of luminous red giant stars.
Characterizing asteroid (152830) Dinkinesh in preparation for the encounter with the NASA Lucy mission: a photometric study
Authors: Mottola Stefano , Denk Tilmann , Marchi Simone , Binzel Richard P , Noll Keith S , Spencer John R , Levison Harold F 
Published: June 2023

ABSTRACT
Main Belt asteroid (152830) Dinkinesh will be the first fly-by target of the Lucy mission on 2023 November 1, during its cruise to the Trojan clouds. We report our photometric time series observations of this target performed on 14 nights over nearly three months during the 2022-23 apparition with the 1.23-m telescope at Calar Alto, Spain, aimed at determining its rotation and photometric properties. We find that Dinkinesh is a slow rotator (Psyn = 52.67 ± 0.04 h) with a moderately large light-curve amplitude (A = 0.39 ± 0.02), which implies an axial ratio a/b ≳ 1.43. Its photometric parameters in the HG-system are HR = 17.17 ± 0.04 and GR = 0.378 ± 0.035 with a colour index $\rm {V \!-\! R}$ = 0.455 ± 0.025. A fit to the IAU $\rm {H,G_1,G_2}$ system results in $H_{\rm R-(H,G_1,G_2)}$ = 17.17 ± 0.14; G1 = 0.37 ± 0.17 and G2 = 0.43 ± 0.04. Assuming that Dinkinesh’s albedo lies within ±2σ of the average value for small S-class asteroids, its spherical surface-equivalent diameter is between 0.66 and 1.36 km.
Varstrometry selected radio-loud candidates of dual and off-nucleus quasars at sub-kpc scales
Authors: Wang Hao-Chen , Wang Jun-Xian , Gu Min-Feng , Liao Mai 
Published: June 2023

ABSTRACT
Dual super massive black holes (SMBHs) at sub-kpc to kpc scales, the product of galaxy mergers, are progenitors of eventually coalescing binary SMBHs. If both or one of the dual SMBHs are accreting, they may appear as dual AGNs or off-nucleus AGNs. Studying such systems is essential to learn the dynamical evolution of binary SMBHs as well as the process of galaxy merging. Recently a novel astrometry-based method named varstrometry has been put forward to search for dual SMBHs at high redshift, as the unsynchronized flux variability of dual AGNs (or off-nucleus AGNs) will cause astrometric jitters detectable by Gaia without spatially resolving them. Based on Gaia varstrometry, we select a rare sample of five radio loud quasars with clear Gaia astrometric jitters. With e-MERLIN observations, we have revealed a single compact radio source for each of them. Remarkably all but one exhibit clear Gaia-radio offsets of ∼9–60 mas. The observed Gaia jitters appear consistent with the expected values. These detected Gaia-radio offsets suggest these candidate dual SMBHs may have projected separations as small as ∼0.01–0.1 arcsec (∼0.1 kpc, depending on the optical flux ratio of two SMBHs). Meanwhile, this work highlights the remarkably high efficiency of Gaia varstrometry selection of jittering sources.
Cytoplasmic Polyadenylation Is an Ancestral Hallmark of Early Development in Animals
Authors: Rouhana Labib , Edgar Allison , Hugosson Fredrik , Dountcheva Valeria , Martindale Mark Q , Ryan Joseph F 
Published: June 2023

AbstractDifferential regulation of gene expression has produced the astonishing diversity of life on Earth. Understanding the origin and evolution of mechanistic innovations for control of gene expression is therefore integral to evolutionary and developmental biology. Cytoplasmic polyadenylation is the biochemical extension of polyadenosine at the 3′-end of cytoplasmic mRNAs. This process regulates the translation of specific maternal transcripts and is mediated by the Cytoplasmic Polyadenylation Element-Binding Protein family (CPEBs). Genes that code for CPEBs are amongst a very few that are present in animals but missing in nonanimal lineages. Whether cytoplasmic polyadenylation is present in non-bilaterian animals (i.e., sponges, ctenophores, placozoans, and cnidarians) remains unknown. We have conducted phylogenetic analyses of CPEBs, and our results show that CPEB1 and CPEB2 subfamilies originated in the animal stem lineage. Our assessment of expression in the sea anemone, Nematostella vectensis (Cnidaria), and the comb jelly, Mnemiopsis leidyi (Ctenophora), demonstrates that maternal expression of CPEB1 and the catalytic subunit of the cytoplasmic polyadenylation machinery (GLD2) is an ancient feature that is conserved across animals. Furthermore, our measurements of poly(A)-tail elongation reveal that key targets of cytoplasmic polyadenylation are shared between vertebrates, cnidarians, and ctenophores, indicating that this mechanism orchestrates a regulatory network that is conserved throughout animal evolution. We postulate that cytoplasmic polyadenylation through CPEBs was a fundamental innovation that contributed to animal evolution from unicellular life.
Body-Plan Reorganization in a Sponge Correlates with Microbiome Change
Authors: Vargas Sergio , Leiva Laura , Eitel Michael , Curdt Franziska , Rohde Sven , Arnold Christopher , Nickel Michael , Schupp Peter , Orsi William D , Adamska Maja , Wörheide Gert 
Published: June 2023

Abstract
Mounting evidence suggests that animals and their associated bacteria interact via intricate molecular mechanisms, and it is hypothesized that disturbances to the microbiome influence animal development. Here, we show that the loss of a key photosymbiont (i.e., bleaching) upon shading correlates with a stark body-plan reorganization in the common aquarium cyanosponge Lendenfeldia chondrodes. The morphological changes observed in shaded sponges include the development of a thread-like morphology that contrasts with the flattened, foliose morphology of control specimens. The microanatomy of shaded sponges markedly differed from that of control sponges, with shaded specimens lacking a well-developed cortex and choanosome. Also, the palisade of polyvacuolar gland-like cells typical in control specimens was absent in shaded sponges. The morphological changes observed in shaded specimens are coupled with broad transcriptomic changes and include the modulation of signaling pathways involved in animal morphogenesis and immune response, such as the Wnt, transforming growth factor β (TGF-β), and TLR–ILR pathways. This study provides a genetic, physiological, and morphological assessment of the effect of microbiome changes on sponge postembryonic development and homeostasis. The correlated response of the sponge host to the collapse of the population of symbiotic cyanobacteria provides evidence for a coupling between the sponge transcriptomic state and the state of its microbiome. This coupling suggests that the ability of animals to interact with their microbiomes and respond to microbiome perturbations has deep evolutionary origins in this group.