bluuebunny/crossref_metadata_2025_split huggingface dataset:
Connecting the early afterglow to the prompt GRB and the central engine in the striped jet model
Authors: Damoulakis Michail , Duran Rodolfo Barniol , Giannios Dimitrios 
Published: June 2023

ABSTRACT
Despite a generally accepted framework for describing the gamma-ray burst (GRB) afterglows, the nature of the compact object at the central engine and the mechanism behind the prompt emission remain debated. The striped jet model is a promising venue to connect the various GRB stages since it gives a robust prediction for the relation of jet bulk acceleration, magnetization, and dissipation profile as a function of distance. Here, we use the constraints of the magnetization and bulk Lorentz of the jet flow at the large scales, where the jet starts interacting with the ambient gas in a large sample of bursts to (i) test the striped jet model for the GRB flow and (ii) study its predictions for the prompt emission and the constraints on the nature of the central engine. We find that the peak of the photospheric component of the emission predicted by the model is in agreement with the observed prompt emission spectra in the majority of the bursts in our sample, with a radiative efficiency of about 10 per cent. Furthermore, we adopt two different approaches to correlate the peak energies of the bursts with the type of central engine to find that more bursts are compatible with a neutron star central engine compared to a black hole one. Lastly, we conclude that the model favours broader distribution of stripe length-scales which results in a more gradual dissipation profile in comparison to the case, where the jet stripes are characterized by a single length-scale.
Effective cosmic density field reconstruction with convolutional neural network
Authors: Chen Xinyi , Zhu Fangzhou , Gaines Sasha , Padmanabhan Nikhil 
Published: June 2023

ABSTRACT
We present a cosmic density field reconstruction method that augments the traditional reconstruction algorithms with a convolutional neural network (CNN). Following previous work, the key component of our method is to use the reconstructed density field as the input to the neural network. We extend this previous work by exploring how the performance of these reconstruction ideas depends on the input reconstruction algorithm, the reconstruction parameters, and the shot noise of the density field, as well as the robustness of the method. We build an eight-layer CNN and train the network with reconstructed density fields computed from the Quijote suite of simulations. The reconstructed density fields are generated by both the standard algorithm and a new iterative algorithm. In real space at z = 0, we find that the reconstructed field is 90 per cent correlated with the true initial density out to $k\sim 0.5 \, \mathrm{ h}\, \rm {Mpc}^{-1}$, a significant improvement over $k\sim 0.2 \, \mathrm{ h}\, \rm {Mpc}^{-1}$ achieved by the input reconstruction algorithms. We find similar improvements in redshift space, including an improved removal of redshift space distortions at small scales. We also find that the method is robust across changes in cosmology. Additionally, the CNN removes much of the variance from the choice of different reconstruction algorithms and reconstruction parameters. However, the effectiveness decreases with increasing shot noise, suggesting that such an approach is best suited to high density samples. This work highlights the additional information in the density field beyond linear scales as well as the power of complementing traditional analysis approaches with machine learning techniques.
Common envelope jets supernova with thermonuclear outburst progenitor for the enigmatic supernova remnant W49B
Authors: Grichener Aldana , Soker Noam 
Published: June 2023

ABSTRACT
We suggest a common envelope jets supernova (CEJSN) origin to the supernova remnant (SNR) W49B where jets launched by a neutron star (NS) that collapsed to a black hole (BH) together with a thermonuclear outburst of the disrupted red super giant’s (RGS’s) core powered and shaped the ejecta. The jets account for the highly non-spherical morphology of W49B and the thermonuclear outburst to its high iron abundance. CEJSNe are violent events powered by jets that a NS or a BH launch as they orbit inside a red supergiant star and accrete mass from its envelope and then from its core. We classify the CEJSN process to either a case where the NS/BH enters the core to form a common envelope evolution (CEE) inside the core or to a case where the NS/BH tidally disrupts the core. In the later case, the core material forms an accretion disc around the NS that might experience a thermonuclear outburst, leading to an energetic event powered by both jets and thermonuclear burning. We term this scenario thermonuclear CEJSN. We find that the maximum core mass that leads to this scenario with a NS is 2 M⊙ ≲ Mcore ≲ 3.5 M⊙. We estimate the event rates of CEJSN that go through tidal disruption of the core by a NS to be 5 per 1000 core collapse supernovae.
Initial sizes of star clusters: implications for cluster dissolution during galaxy evolution
Authors: Reina-Campos Marta , Sills Alison , Bichon Godefroy 
Published: June 2023

ABSTRACT
Massive star clusters are often used as tracers of galaxy formation and assembly. In order to do so, we must understand their properties at formation, and how those properties change with time, galactic environment, and galaxy assembly history. The two most important intrinsic properties that govern star cluster evolution are mass and radius. In this paper, we investigate 10 theoretically and observationally motivated initial size–mass relations for star clusters, and evolve populations of clusters through galaxy formation models. We compare our results to each other and to observations of cluster populations in M83, M31, and the Milky Way. We find that none of our size–mass relations agree with the observations after 6–10 Gyr of evolution. We can successfully reproduce the cluster mass functions with models that have a small range of initial radii, and which do not allow cluster radii to change with time. However, these models do not agree with our understanding of cluster evolution, which does involve radius evolution, and do not match the observed distributions of radii. We note that there is a region of parameter space where clusters are optimally protected from both tidal shocks and evaporation due to two-body relaxation. Clusters that are allowed to evolve into this parameter space will likely survive. An improved understanding of both mass and radius evolution of star clusters in realistic, time-varying galactic potentials is necessary to appropriately make the connection between present-day cluster properties and their use as tracers of galaxy formation and assembly.
Analysis of accretion disc structure and stability using open code for vertical structure
Authors: Tavleev A S , Lipunova G V , Malanchev K L 
Published: June 2023

ABSTRACT
Radial structure of accretion discs around compact objects is often described using analytic approximations which are derived from averaging or integrating vertical structure equations. For non-solar chemical composition, partial ionization, or for supermassive black holes, this approach is not accurate. Additionally, radial extension of ‘analytically-described’ disc zones is not evident in many cases. We calculate vertical structure of accretion discs around compact objects, with and without external irradiation, with radiative and convective energy transport taken into account. For this, we introduce a new open Python code, allowing different equations of state and opacity laws, including tabular values. As a result, radial structure and stability ‘S-curves’ are calculated for specific disc parameters and chemical composition. In particular, based on more accurate power-law approximations for opacity in the disc, we supply new analytic formulas for the farthest regions of the hot disc around stellar-mass object. On calculating vertical structure of a self-irradiated disc, we calculate a self-consistent value of the irradiation parameter Cirr for stationary α-disc. We find that, for a fixed shape of the X-ray spectrum, Cirr depends weakly on the accretion rate but changes with radius, and the dependence is driven by the conditions in the photosphere and disc opening angle. The hot zone extent depends on the ratio between irradiating and intrinsic flux: corresponding relation for $T_{\rm irr,\, crit}$ is obtained.
Keck spectroscopy of NGC 1052-DF9: stellar populations in the context of the NGC 1052 group
Authors: Gannon Jonah S , Buzzo Maria Luisa , Ferré-Mateu Anna , Forbes Duncan A , Brodie Jean P , Romanowsky Aaron J 
Published: June 2023

ABSTRACT
In this study, we use Keck/Keck Cosmic Web Imager spectroscopy to measure the age, metallicity, and recessional velocity of NGC 1052-DF9 (DF9), a dwarf galaxy in the NGC 1052 group. We compare these properties to those of two other galaxies in the group, NGC 1052-DF2 and NGC 1052-DF4, which have low dark matter content. The three galaxies are proposed constituents of a trail of galaxies recently hypothesized to have formed as part of a ‘bullet dwarf’ collision. We show that the ages and total metallicities of the three galaxies are within uncertainties of one another which may be expected if they share a related formation pathway. However, the recessional velocity we recover for DF9 (1680 ± 10 km s−1) is higher than predicted for a linearly projected interpretation of the ‘bullet dwarf’ trail. DF9 is then either not part of the trail or the correlation of galaxy velocities along the trail is not linear in 2D projection due to their 3D geometry. After examining other proposed formation pathways for the galaxies, none provide a wholly satisfactory explanation for all of their known properties. We conclude further work is required to understand the formation of this interesting group of galaxies.
Discovery of delta Scuti variables in eclipsing binary systems II. Southern TESS field search
Authors: Kahraman Aliçavuş F , Çoban Ç G , Çelik E , Dogan D S , Ekinci O , Aliçavuş F 
Published: June 2023

ABSTRACT
The presence of pulsating stars in eclipsing binary systems (EBs) makes these objects significant since they allow us to investigate the stellar interior structure and evolution. Different types of pulsating stars could be found in EBs, such as δ Scuti variables. δ Scuti stars in EBs have been known for decades, and the increasing number of such systems is important for understanding pulsational structure. Hence, in this study, research was carried out on the southern TESS field to discover new δ Scuti stars in EBs. We produced an algorithm to search for detached and semidetached EBs considering three steps: the orbital period (Porb)’s harmonics in the Fourier spectrum, skewness of the light curves, and classification of upsilon program. If two of these steps classify a system as an EB, the algorithm also identifies it as an EB. The TESS pixel files of targets were also analysed to see whether the fluxes were contaminated by other systems. No contamination was found. We researched the existence of pulsation through EBs with a visual inspection. To confirm δ Scuti-type oscillations, the binary variation was removed from the light curve, and residuals were analysed. Consequently, we identified 42 δ Scuti candidates in EBs. The Porb, L, and MV of systems were calculated. Their positions on the H–R diagram and the known orbital-pulsation period relationship were analysed. We also examined our targets to see if any of them showed frequency modulation with the orbital period and discovered one candidate of tidally tilted pulsators.
What causes the formation of discs and end of bursty star formation?
Authors: Hopkins Philip F , Gurvich Alexander B , Shen Xuejian , Hafen Zachary , Grudić Michael Y , Kurinchi-Vendhan Shalini , Hayward Christopher C , Jiang Fangzhou , Orr Matthew E , Wetzel Andrew , Kereš Dušan , Stern Jonathan , Faucher-Giguère Claude-André , Bullock James , Wheeler Coral , El-Badry Kareem , Loebman Sarah R , Moreno Jorge , Boylan-Kolchin Michael , Quataert Eliot 
Published: June 2023

ABSTRACT
As they grow, galaxies can transition from irregular/spheroidal with ‘bursty’ star formation histories (SFHs), to discy with smooth SFHs. But even in simulations, the direct physical cause of such transitions remains unclear. We therefore explore this in a large suite of numerical experiments re-running portions of cosmological simulations with widely varied physics, further validated with existing FIRE simulations. We show that gas supply, cooling/thermodynamics, star formation model, Toomre scale, galaxy dynamical times, and feedback properties do not have a direct causal effect on these transitions. Rather, both the formation of discs and cessation of bursty star formation are driven by the gravitational potential, but in different ways. Disc formation is promoted when the mass profile becomes sufficiently centrally concentrated in shape (relative to circularization radii): we show that this provides a well-defined dynamical centre, ceases to support the global ‘breathing modes’ that can persist indefinitely in less-concentrated profiles and efficiently destroy discs, promotes orbit mixing to form a coherent angular momentum, and stabilizes the disc. Smooth SF is promoted by the potential or escape velocity Vesc (not circular velocity Vc) becoming sufficiently large at the radii of star formation that cool, mass-loaded (momentum-conserving) outflows are trapped/confined near the galaxy, as opposed to escaping after bursts. We discuss the detailed physics, how these conditions arise in cosmological contexts, their relation to other correlated phenomena (e.g. inner halo virialization, vertical disc ‘settling’), and observations.
The challenges of identifying Population III stars in the early Universe
Authors: Katz Harley , Kimm Taysun , Ellis Richard S , Devriendt Julien , Slyz Adrianne 
Published: June 2023

ABSTRACT
The recent launch of JWST has enabled the exciting prospect of detecting the first generation of metal-free, Population III (Pop. III) stars. Determining characteristics that robustly signify Pop. III stars against other possible contaminants represents a key challenge. To this end, we run high-resolution (sub-pc) cosmological radiation hydrodynamics simulations of the region around a dwarf galaxy at z ≥ 10 to predict the emission line signatures of the Pop. III/Pop. II transition. We show that the absence of metal emission lines is a poor diagnostic of Pop. III stars because metal-enriched galaxies can maintain low [O iii] 5007 Å that may be undetectable due to sensitivity limits. Combining spectral hardness probes (e.g. He ii 1640 Å/H α) with metallicity diagnostics is more likely to probe metal-free stars, although contamination from Wolf−Rayet stars, X-ray binaries, or black holes may be important. The hard emission from Pop. III galaxies fades fast due to the short stellar lifetimes of massive stars, which could further inhibit detection. Pop. III stars may be identifiable after they evolve off the main sequence due to the cooling radiation from nebular gas or a supernova remnant; however, these signatures are also short-lived (i.e. few Myr). Contaminants including flickering black holes might confuse this diagnostic. While JWST will provide a unique opportunity to spectroscopically probe the nature of the earliest galaxies, both the short time-scales associated with pristine systems and ambiguities in interpreting emission lines may hinder progress. Special care will be needed before claiming the discovery of systems with pure Pop. III stars.
Evidence of radius inflation in radiative GCM models of WASP-76b due to the advection of potential temperature
Authors: Sainsbury-Martinez Felix , Tremblin Pascal , Schneider Aaron David , Carone Ludmila , Baraffe Isabelle , Chabrier Gilles , Helling Christiane , Decin Leen , Jørgensen Uffe Gråe 
Published: June 2023

ABSTRACT
Understanding the discrepancy between the radii of observed hot Jupiters and standard ‘radiative-convective’ models remains a hotly debated topic in the exoplanet community. One mechanism which has been proposed to bridge this gap, and which has recently come under scrutiny, is the vertical advection of potential temperature from the irradiated outer atmosphere deep into the interior, heating the deep unirradiated atmosphere, warming the internal adiabat, and resulting in radius inflation. Specifically, a recent study which explored the atmosphere of WASP-76b using a 3D non-grey GCM suggested that their models lacked radius inflation, and hence any vertical enthalpy advection. Here we perform additional analysis of these, and related models, focusing on an explicit analysis of vertical enthalpy transport and the resulting heating of the deep atmosphere compared with 1D models. Our results indicate that, after any evolution linked with initialization, all the WASP-76b models considered here exhibit significant vertical enthalpy transport, heating the deep atmosphere significantly when compared with standard 1D models. Furthermore, comparison of a long time-scale (and hence near steady-state) model with a Jupiter-like internal-structure model suggests not only strong radius-inflation, but also that the model radius, 1.98 RJ, may be comparable with observations (1.83 ± 0.06 RJ). We thus conclude that the vertical advection of potential temperature alone is enough to explain the radius inflation of WASP-76b, and potentially other irradiated gas giants, albeit with the proviso that the exact strength of the vertical advection remains sensitive to model parameters, such as the inclusion of deep atmospheric drag.
Possible contribution of X-ray binary jets to the Galactic cosmic ray and neutrino flux
Authors: Kantzas D , Markoff S , Cooper A J , Gaggero D , Petropoulou M , De La Torre Luque P 
Published: June 2023

ABSTRACT
For over a century, the identification of high-energy cosmic ray (CR) sources remains an open question. For Galactic CRs with energy up to 1015 eV, supernova remnants (SNRs) have traditionally been thought the main candidate source. However, recent TeV γ-ray observations have questioned the SNR paradigm. Propagating CRs are deflected by the Galactic magnetic field, hence, γ-rays and neutrinos produced via inelastic hadronic interactions are the only means for unveiling the CR sources. In this work, we study the γ-ray and neutrino emission produced by CRs accelerated inside Galactic jets of stellar-mass black holes in X-ray binaries (BHXBs). We calculate the intrinsic neutrino emission of two prototypical BHXBs , Cygnus X–1 and GX 339–4, for which we have high-quality, quasi-simultaneous multiwavelength spectra. Based on these prototypical sources, we discuss the likelihood of the 35 known Galactic BHXBs to be efficient CR accelerators. Moreover, we estimate the potential contribution to the CR spectrum of a viable population of BHXBs that reside in the Galactic plane. When these BHXBs go into outburst, they may accelerate particles up to hundreds of TeV that contribute to the diffuse γ-ray and neutrino spectra while propagating in the Galactic medium. Using HERMES, an open-source code that calculates the hadronic processes along the line of sight, we discuss the contribution of BHXBs to the diffuse γ-ray and neutrino fluxes, and compare these to their intrinsic γ-ray and neutrino emissions. Finally, we discuss the contribution of BHXBs to the observed spectrum of Galactic CRs.
Atmospheres as windows into sub-Neptune interiors: coupled chemistry and structure of hydrogen–silane–water envelopes
Authors: Misener William , Schlichting Hilke E , Young Edward D 
Published: June 2023

ABSTRACT
Sub-Neptune exoplanets are commonly hypothesized to consist of a silicate-rich magma ocean topped by a hydrogen-rich atmosphere. Previous work studying the outgassing of silicate material has demonstrated that such atmosphere–interior interactions can affect the atmosphere’s overall structure and extent. However, these models only considered SiO in an atmosphere of hydrogen gas, without considering chemical reactions between them. Here, we couple calculations of the chemical equilibrium between H, Si, and O species with an atmospheric structure model. We find that substantial amounts of silane, SiH4, and water, H2O, are produced by the interaction between the silicate-rich interior and hydrogen-rich atmosphere. These species extend high into the atmosphere, though their abundance is greatest at the hottest, deepest regions. For example, for a 4 M⊕ planet with an equilibrium temperature of 1000 K, a base temperature of 5000 K, and a 0.1 M⊕ hydrogen envelope, silicon species and water can comprise 30 per cent of the atmosphere by number at the bottom of the atmosphere. Due to this abundance enhancement, we find that convection is inhibited at temperatures ≳2500 K. This temperature is lower, implying that the resultant non-convective region is thicker, than was found in previous models that did not account for atmospheric chemistry. Our findings show that significant endogenous water is produced by magma–hydrogen interactions alone, without the need to accrete ice-rich material. We discuss the observability of the signatures of atmosphere–interior interaction and directions for future work, including condensate lofting and more complex chemical networks.
A unified exploration of the chronology of the Galaxy
Authors: Stokholm Amalie , Aguirre Børsen-Koch Víctor , Stello Dennis , Hon Marc , Reyes Claudia 
Published: June 2023

ABSTRACT
The Milky Way has distinct structural stellar components linked to its formation and subsequent evolution, but disentangling them is non-trivial. With the recent availability of high-quality data for a large numbers of stars in the Milky Way, it is a natural next step for research in the evolution of the Galaxy to perform automated explorations with unsupervised methods of the structures hidden in the combination of large-scale spectroscopic, astrometric, and asteroseismic data sets. We determine precise stellar properties for 21 076 red giants, mainly spanning 2–15 kpc in Galactocentric radii, making it the largest sample of red giants with measured asteroseismic ages available to date. We explore the nature of different stellar structures in the Galactic disc by using Gaussian mixture models as an unsupervised clustering method to find substructure in the combined chemical, kinematic, and age subspace. The best-fitting mixture model yields four distinct physical Galactic components in the stellar disc: the thin disc, the kinematically heated thin disc, the thick disc, and the stellar halo. We find hints of an age asymmetry between the Northern and Southern hemisphere, and we measure the vertical and radial age gradient of the Galactic disc using the asteroseismic ages extended to further distances than previous studies.