bluuebunny/crossref_metadata_2025_split huggingface dataset:
The hot circumgalactic medium in the eROSITA All-Sky Survey
Authors: Zhang Yi , Comparat Johan , Ponti Gabriele , Merloni Andrea , Nandra Kirpal , Haberl Frank , Truong Nhut , Pillepich Annalisa , Locatelli Nicola , Zhang Xiaoyuan , Sanders Jeremy , Zheng Xueying , Liu Ang , Popesso Paola , Liu Teng , Predehl Peter , Salvato Mara , Shreeram Soumya , Yeung Michael C. H. 
Published: July 2024

Aims. Understanding how the properties of galaxies relate to the properties of the hot circum-galactic medium (CGM) around them can constrain galaxy evolution models. We aim to measure the scaling relations between the X-ray luminosity of the hot CGM and the fundamental properties (stellar mass and halo mass) of a galaxy.
Methods. We measured the X-ray luminosity of the hot CGM based on the surface brightness profiles of central galaxy samples measured from Spectrum Roentgen Gamma (SRG)/eROSITA all-sky survey data. We related the X-ray luminosity to the galaxies’ stellar and halo mass, and we compared the observed relations to the self-similar model and intrinsic (i.e., not forward-modeled) output of the IllustrisTNG, EAGLE, and SIMBA simulations.
Results. The average hot CGM X-ray luminosity (LX, CGM) correlates with the galaxy’s stellar mass (M*). It increases from (1.6 ± 2.1) × 1039 erg s−1 to (3.4 ± 0.3) × 1041 erg s−1, when log(M*) increases from 10.0 to 11.5. A power law describes the correlation as log(LX, CGM) = (2.4 ± 0.1)×log(M*)+(14.6 ± 1.5). The hot CGM X-ray luminosity as a function of halo mass is measured within log(M500c) = 11.3 − 13.7, extending our knowledge of the scaling relation by more than two orders of magnitude. LX, CGM increases with M500c from (3.0 ± 1.6) × 1039 erg s−1 at log(M500c) = 11.3 to (1.3 ± 0.1) × 1042 erg s−1 at log(M500c) = 13.7. The relation follows a power law of log(LX, CGM) = (1.32 ± 0.05)×log(M500c)+(24.1 ± 0.7). Our observations highlight the necessity of non-gravitational processes at the galaxy group scale while suggesting these processes are sub-dominant at the galaxy scale. We show that the outputs of current cosmological galaxy simulations generally align with the observational results uncovered here but with possibly important deviations in selected mass ranges.
Conclusions. We explore, at the low mass end, the average scaling relations between the CGM X-ray luminosity and the galaxy’s stellar mass or halo mass, which constitutes a new benchmark for galaxy evolution models and feedback processes.
The role of active galactic nucleus feedback on the evolution of dwarf galaxies from cosmological simulations
Authors: Arjona-Gálvez Elena , Di Cintio Arianna , Grand Robert J. J. 
Published: July 2024

Aims. Recent observational studies suggest that feedback from active galactic nuclei (AGNs) may play an important role in the formation and evolution of dwarf galaxies, an issue that has received little attention from a theoretical perspective.
Methods. We investigated this using two sets of 12 cosmological magnetohydrodynamic simulations of the formation of dwarf galaxies
(108.3M⊙ ≤ M* ≤ 109.8M⊙):

one set using a version of the AURIGA galaxy formation physics model including AGN feedback and a parallel set with AGN feedback turned off.
Results. We show that the full-physics AGN runs satisfactorily reproduce several scaling relations, including the black-hole-to-stellar mass (MBH-M⋆), the black-hole-to-sigma (MBH-σ⋆), and the baryonic Tully-Fisher relation. We find that the global star formation (SF) of galaxies run with an AGN is reduced compared to the one in which the AGN has been turned off, suggesting that AGN feedback is a viable way of suppressing SF in dwarf galaxies, even though none of our galaxies is completely quenched by z = 0. Furthermore, we find a tight correlation between the median SF rates and the MBH/M⋆ ratio in our simulated dwarfs. Star formation is suppressed due to gas heating in the vicinity of the AGN: less HI gas is available in AGN runs, though the total amount of gas is preserved across the two settings within each galaxy. This indicates that the main effect of AGN feedback in our dwarfs is to heat up and push the gas away from the galaxy’s centre rather than expelling it completely. Finally, we show that the two galaxies harbouring the largest supermassive black holes have suffered a considerable (up to ∼65%) reduction in their central dark matter density, pinpointing the role of AGNs in determining the final dark matter mass distribution within dwarf galaxies. This pilot paper highlights the importance of modelling AGN feedback at the lowest mass scales and the impact this can have on dwarf galaxy evolution.
Observational signatures of the dust size evolution in isolated galaxy simulations
Authors: Matsumoto Kosei , Hirashita Hiroyuki , Nagamine Kentaro , van der Giessen Stefan , Romano Leonard E. C. , Relaño Monica , De Looze Ilse , Baes Maarten , Nersesian Angelos , Camps Peter , Hou Kuan-chou , Oku Yuri 
Published: July 2024

Aims. We aim to provide observational signatures of the dust size evolution in the interstellar medium. In particular, we explore indicators of the polycyclic aromatic hydrocarbon (PAH) mass fraction (qPAH), defined as the mass fraction of PAHs relative to the total dust grains. In addition, we validate our dust evolution model by comparing the observational signatures from our simulations to observations.
Methods. We used the hydrodynamic simulation code, GADGET4-OSAKA to model the dust properties of Milky Way-like and NGC 628-like galaxies representing star-forming galaxies. This code incorporates the evolution of grain size distributions driven by dust production and interstellar processing. Furthermore, we performed post-processing dust radiative transfer calculations with SKIRT based on the hydrodynamic simulations to predict the observational properties of the simulations.
Results. We find that the intensity ratio between 8 and 24 μm (Iν(8 μm)/Iν(24 μm)) is correlated with qPAH and can be used as an indicator of the PAH mass fraction. However, this ratio is influenced by the local radiation field. We suggest the 8 μm-to-total infrared intensity ratio (νIν(8 μm)/ITIR) as another indicator of the PAH mass fraction, since it is tightly correlated with the PAH mass fraction. Furthermore, we explored the spatially resolved evolutionary properties of the PAH mass fraction in the simulated Milky Way-like galaxy using νIν(8 μm)/ITIR. We find that the spatially resolved PAH mass fraction increases with metallicity at Z ≲ 0.2 Z⊙ due to the interplay between accretion and shattering, whereas it decreases at Z ≳ 0.2 Z⊙ because of coagulation. Also, coagulation decreases the PAH mass fraction in regions with a high hydrogen surface density. Finally, we compared the above indicators in the NGC 628-like simulation with those observed in NGC 628 by Herschel, Spitzer, and JWST. Consequently, we find that our simulation underestimates the PAH mass fraction throughout the entire galaxy by a factor of ~8 on average. This could be due to the efficient loss of PAHs by coagulation in our model, suggesting that our treatment of PAHs in dense regions needs to be improved.
Abundances of neutron-capture elements in selected solar-type stars
Authors: Sheminova Valentina , Baratella Martina , D’Orazi Valentina 
Published: July 2024

Aims. The primary objective of this study is to accurately determine the abundances of Cu, Sr, Y, Zr, Ba, La, and Ce in selected solar-type stars. This will allow us to establish observational abundance–metallicity and abundance–age relations and to explore the reasons for the excess of Ba compared to other s-elements in younger solar-type stars. The chosen s-process elements are critical diagnostics for understanding the chemical evolution of our Galaxy.
Methods. We analysed HARPS spectra with a high resolution (R = 115 000) and high signal-to-noise ratio (close to 100) of main-sequence solar-type FGK stars with metallicities from −0.15 to +0.35 dex and ages from 2 to 14 Gyr using one-dimensional (1D) local thermodynamic equilibrium (LTE) synthesis and MARCS atmospheric models. In the procedure of fitting synthetic to observed line profiles, the free parameters included abundance and microturbulent and macroturbulent velocity. The macroturbulent velocity can substantially compensate for non-local thermodynamic equilibrium (NLTE) effects in the line core.
Results. The resulting elemental abundance [X/H] increases with metallicity and age for solar-type stars. The ratio of the abundances of s-process elements [s/Fe] increases with decreasing metallicity and age, while the [Cu/Fe] ratio increases with both metallicity and age. These observed trends agree well with published observational data and with predictions from Galactic chemical evolution (GCE) models. A small [Ba/Fe] enhancement of 0.08 ± 0.08 dex has been detected in seven younger stars with an average age of 2.8 ± 0.6 Gyr. Compared to the abundances of other s-process elements, [Ba/Fe] is 0.07 and 0.08 dex higher than La and Ce on average, respectively. Furthermore, we find that the [Ba/Fe] ratio increases with increasing chromospheric activity. The average [Ba/Fe] for the three most active stars is 0.15 ± 0.10 dex higher than that of the other stars. Chromospheric activity, characterised by stronger magnetic fields found in active regions such as pores, spots, plages, and networks, can significantly alter the physical conditions in the formation layers of the Ba lines. Our primary conclusion is that to account for the observed excess of [Ba/Fe] abundance in younger stars, it is essential to use more complex atmospheric models that incorporate magnetic structures.
Impact of the numerical conversion to optical depth on the transfer of polarized radiation
Authors: D’Anna Matteo , Janett Gioele , Belluzzi Luca 
Published: July 2024

Context. Making the conversion from the geometrical spatial scale to the optical depth spatial scale is useful in obtaining numerical solutions for the radiative transfer equation. This is because it allows for the use of exponential integrators, while enforcing numerical stability. Such a conversion involves the integration of the total opacity of the medium along the considered ray path. This is usually approximated by applying a piecewise quadrature in each spatial cell of the discretized medium. However, a rigorous analysis of this numerical step is lacking.
Aims. This work is aimed at clearly assessing the performance of different optical depth conversion schemes with respect to the solution of the radiative transfer problem for polarized radiation, out of the local thermodynamic equilibrium.
Methods. We analyzed different optical depth conversion schemes and their combinations with common formal solvers, both in terms of the rate of convergence as a function of the number of spatial points and the accuracy of the emergent Stokes profiles. The analysis was performed in a 1D semi-empirical model of the solar atmosphere, both in the absence and in the presence of a magnetic field. We solved the transfer problem of polarized radiation in different settings: the continuum, the photospheric Sr I line at 4607 Å modeled under the assumption of complete frequency redistribution, and the chromospheric Ca I line at 4227 Å, taking the partial frequency redistribution effects into account during the modeling.
Results. High-order conversion schemes generally outperform low-order methods when a sufficiently high number of spatial grid points is considered. In the synthesis of the emergent Stokes profiles, the convergence rate, as a function of the number of spatial points, is impacted by both the conversion scheme and formal solver. The use of low-order conversion schemes significantly reduces the accuracy of high-order formal solvers.
Conclusions. In practical applications, the use of low-order optical depth conversion schemes introduces large numerical errors in the formal solution. To fully exploit high-order formal solvers and obtain accurate synthetic emergent Stokes profiles, it is necessary to use high-order optical depth conversion schemes.
Carbon enrichment in APOGEE disk stars as evidence of mass transfer in binaries
Authors: Foster Steve , Schiavon Ricardo P. , de Castro Denise B. , Lucatello Sara , Daher Christine , Penoyre Zephyr , Price-Whelan Adrian , Badenes Carles , Fernández-Trincado José G. , García-Hernández Domingo Aníbal , Holtzman Jon , Jönsson Henrik , Shetrone Matthew 
Published: July 2024

Context. Carbon abundances in first-ascent giant stars are usually lower than those of their main-sequence counterparts. At moderate metallicities, stellar evolution of single stars cannot account for the existence of red-giant branch stars with enhanced carbon abundances. The phenomenon is usually interpreted as resulting from past mass transfer from an evolved binary companion now in the white dwarf evolutionary stage.
Aims. We aim to confirm the links between [C/O] enhancement, s-process element enhancement and binary fraction using large-scale catalogues of stellar abundances and probable binary stars.
Methods. We use a large data set from the 17th data release of the SDSS-IV/APOGEE 2 survey to identify carbon-enhanced stars in the Galactic disk. We identify a continuum of carbon enrichment throughout three different sub-populations of disk stars and explore links between the degree of carbon enrichment and binary frequency, metallicity and chemical compositions.
Results. We verify a clear correlation between binary frequency and enhancement in the abundances of both carbon and cerium, lending support to the scenario whereby carbon-enhanced stars are the result of mass transfer by an evolved binary companion. In addition, we identify clustering in the carbon abundances of high-α disk stars, suggesting that those on the high metallicity end are likely younger, in agreement with theoretical predictions for the presence of a starburst population following the gas-rich merger of the Gaia-Enceladus/Sausage system.
Neural network reconstruction of density and velocity fields from the 2MASS Redshift Survey
Authors: Lilow Robert , Ganeshaiah Veena Punyakoti , Nusser Adi 
Published: July 2024

Aims. Our aim is to reconstruct the 3D matter density and peculiar velocity fields in the local Universe up to a distance of 200 h−1 Mpc from the Two-Micron All-Sky Redshift Survey (2MRS) using a neural network (NN).
Methods. We employed an NN with a U-net autoencoder architecture and a weighted mean squared error loss function trained separately to output either the density or velocity field for a given input grid of galaxy number counts. The NN was trained on mocks derived from the Quijote N-body simulations, incorporating redshift-space distortions (RSDs), galaxy bias, and selection effects closely mimicking the characteristics of 2MRS. The trained NN was benchmarked against a standard Wiener filter (WF) on a validation set of mocks before applying it to 2MRS.
Results. The NN reconstructions effectively approximate the mean posterior estimate of the true density and velocity fields conditioned on the observations. They consistently outperform the WF in terms of reconstruction accuracy and effectively capture the nonlinear relation between velocity and density. The NN-reconstructed bulk flow of the total survey volume exhibits a significant correlation with the true mock bulk flow, demonstrating that the NN is sensitive to information on “super-survey” scales encoded in the RSDs. When applied to 2MRS, the NN successfully recovers the main known clusters, some of which are partially in the Zone of Avoidance. The reconstructed bulk flows in spheres of different radii less than 100 h−1 Mpc are in good agreement with a previous 2MRS analysis that required an additional external bulk flow component inferred from directly observed peculiar velocities. The NN-reconstructed peculiar velocity of the Local Group closely matches the observed Cosmic Microwave Background dipole in amplitude and Galactic latitude, and only deviates by 18° in longitude. The NN-reconstructed fields are publicly available.
Evolutionary pathways of disk galaxies with different sizes
Authors: Ma Hong-Chuan , Du Min , Ho Luis C. , Sheng Ming-Jie , Liao Shihong 
Published: July 2024

Aims. This work delves into the complex interaction between disk galaxies and their host dark matter halos. It specifically focuses on scenarios with minimal external (“nurture”) influences such as mergers and substantial tidal interactions. The study uncovers the varied evolutionary paths of disk galaxies of different sizes, shaped by the initial conditions of their parent dark matter halos and subsequent internal processes. Thus, we can explore the “nature” of these galaxies.
Methods. From the TNG50 simulation, a sample of 836 central disk galaxies with tiny stellar halos is chosen to study the inherent evolution of galaxies driven by nature. These galaxies are classified as compact, normal, or extended by referencing their locations on the mass-size (M⋆ − R½) diagram. Scaling relations were then established to measure the correlations driven by internal mechanisms.
Results. This research demonstrates the distinctive evolutionary pathways of galaxies with different sizes in IllustrisTNG simulations, primarily driven by their nature. It is confirmed that disk galaxies inherit the angular momentum of their parent dark matter halos. More compact galaxies form earlier within halos that exhibit a lower specific angular momentum through heightened star formation during the early phase at redshifts above 2. During the later phase, the size of extended galaxies experiences more pronounced growth by accreting gas with a high angular momentum. Additionally, we reveal that many key characteristics of galaxies are linked to their mass and size: (1) compact galaxies tend to exhibit higher metal content, proportional to the potential well, M⋆/R½; (2) compact galaxies host more massive bulges and black holes, along with a higher central concentration. Furthermore, our analysis indicates that galaxies of all types continue to actively engage in star formation, with no evident signs of quenching attributed to their varying sizes and angular momenta.
The chemical composition of CO-rich comet C/2023 H2 (Lemmon)
Authors: Lippi M. , Ferellec L. , Opitom C. , Faggi S. , Mumma M. J. , Villanueva G. L. 
Published: July 2024

Aims. We report on the composition of comet C/2023 H2 (Lemmon) (hereafter C/2023 H2) as measured with CRIRES+ at VLT/ESO, under the Director Discretionary Time program: 2112.C-5015.
Methods. We observed C/2023 H2 between November 24 and 27, 2023, after perihelion and during its close approach to Earth. We used three settings sampling the spectral region from ≈2.5 to 5 µm, to search for fluorescence emission lines of H2O, HCN, C2H2, NH3, C2H6, H2CO, CH3OH, CH4, and CO.
Results. C/2023 H2 spectra are dominated by signatures from hyper-volatile species, namely CO, C2H6, and CH4, while it is particularly difficult to identify lines from less volatile species such as water or methanol. When compared to other comets, C/2023 H2 has an overall typical-to-enriched composition, with CO showing one of the highest infrared values reported so far in Solar System comets within 2 au from the Sun. In this respect, C/2023 H2 shares many similarities with C/2013 R1 (Lovejoy), C/2009 P1 (Garrad), and C/1999 T1 (McNaught-Hartley), although still being rather unique. Results from the analysis of optical spectra (≈300–650 nm) obtained on November 16, 2023, using the Intermediate Dispersion Spectrograph at the Isaac Newton Telescopes are consistent with the infrared ones.
Conclusions. Assuming that the composition of C/2023 H2 is original, this comet most likely formed in a region of the disc where CO was particularly enriched, or it could have been captured from other planetary systems forming in the Sun’s birth cluster. Similarities with a few other comets suggest the existence of a sub-class of CO-enriched comets, which may be currently under-sampled. Alternatively, water sublimation may have been ineffective due to the presence of a thick dust mantle covering the nucleus surface.
Rotational state-to-state transition rate coefficients for H2O + H2O collisions at nonequilibrium conditions
Authors: Mandal Bikramaditya , Zoltowski Michal , Cordiner Martin , Lique Francois , Babikov Dmitri 
Published: July 2024

Aims. The goal is to develop a database of rate coefficients for rotational state-to-state transitions in H2O + H2O collisions that is suitable for the modeling of energy transfer in nonequilibrium conditions, in which the distribution of rotational states of H2O deviates from local thermodynamic equilibrium.
Methods. A two-temperature model was employed that assumed that although there is no equilibrium between all possible degrees of freedom in the system, the translational and rotational degrees of freedom can be expected to achieve their own equilibria independently, and that they can be approximately characterized by Boltzmann distributions at two different temperatures, Tkin and Trot.
Results. Upon introducing our new parameterization of the collisional rates, taking into account their dependence on both Tkin and Trot, we find a change of up to 20% in the H2O rotational level populations for both ortho and para-H2O for the part of the cometary coma where the nonequilibrium regime occurs.
MUSE spectroscopy of the high abundance discrepancy planetary nebula NGC 6153
Authors: Gómez-Llanos V. , García-Rojas J. , Morisset C. , Monteiro H. , Jones D. , Wesson R. , Boffin H. M. J. , Corradi R. L M. 
Published: July 2024

Context. The abundance discrepancy problem in planetary nebulae (PNe) has long puzzled astronomers. NGC 6153, with its high abundance discrepancy factor (ADF ~ 10), provides a unique opportunity to study the chemical structure and ionisation processes within these objects.
Aims. We aim to understand the chemical structure and ionisation processes in this high-ADF nebula by constructing detailed emission line maps and examining variations in electron temperature and density. This study also explores the discrepancies between ionic abundances derived from collisional and recombination lines, shedding light on the presence of multiple plasma components.
Methods. We used the MUSE spectrograph to acquire IFU data covering the wavelength range 4600–9300 Å with a spatial sampling of 0.2 arcsec and spectral resolutions ranging from R = 1609 to R = 3506. We created emission line maps for 60 lines and two continuum regions. We developed a tailored methodology for the analysis of the data, including correction for recombination contributions to auroral lines and the contributions of different plasma phases.
Results. Our analysis confirmed the presence of a low-temperature plasma component in NGC 6153. We find that electron temperatures derived from recombination line and continuum diagnostics are significantly lower than those derived from collisionally excited line diagnostics. Ionic chemical abundance maps were constructed, considering the weight of the cold plasma phase in the H I emission. Adopting this approach we found ionic abundances that could be up to 0.2 dex lower for those derived from CELs and up to 1.1 dex higher for those derived from RLs than in the case of a homogeneous H I emission. The abundance contrast factor (ACF) between both plasma components was defined, with values, on average, 0.9 dex higher than the ADF. Different methods for calculating ionisation correction factors (ICFs), including state-of-the-art literature ICFs and machine learning techniques, yielded consistent results.
Conclusions. Our findings emphasise that accurate chemical abundance determinations in high-ADF PNe must account for multiple plasma phases. Future research should focus on expanding this methodology to a broader sample of PNe, with spectra deep enough to gather physical condition information of both plasma components, which will enhance our understanding of their chemical compositions and the underlying physical processes in these complex objects.