bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early-timeγ-ray constraints on cosmic-ray acceleration in the core-collapse SN 2023ixf with theFermiLarge Area Telescope
Authors: Martí-Devesa G. , Cheung C. C. , Di Lalla N. , Renaud M. , Principe G. , Omodei N. , Acero F. 
Published: April 2024

Context.While supernova remnants (SNRs) have been considered the most relevant Galactic cosmic ray (CR) accelerators for decades, core-collapse supernovae (CCSNe) could accelerate particles during the earliest stages of their evolution and hence contribute to the CR energy budget in the Galaxy. Some SNRs have indeed been associated with TeVγ-rays, yet proton acceleration efficiency during the early stages of an SN expansion remains mostly unconstrained.Aims.The multi-wavelength observation of SN 2023ixf, a Type II supernova (SN) in the nearby galaxy M 101 (at a distance of 6.85 Mpc), opens the possibility to constrain CR acceleration within a few days after the collapse of the red super-giant stellar progenitor. With this work, we intend to provide a phenomenological, quasi-model-independent constraint on the CR acceleration efficiency during this event at photon energies above 100 MeV.Methods.We performed a maximum-likelihood analysis ofγ-ray data from theFermiLarge Area Telescope up to one month after the SN explosion. We searched for high-energy, non-thermal emission from its expanding shock, and estimated the underlying hadronic CR energy reservoir assuming a power-law proton distribution consistent with standard diffusive shock acceleration.Results.We do not find significantγ-ray emission from SN 2023ixf. Nonetheless, our non-detection provides the first limit on the energy transferred to the population of hadronic CRs during the very early expansion of a CCSN.Conclusions.Under reasonable assumptions, our limits would imply a maximum efficiency on the CR acceleration of as low as 1%, which is inconsistent with the common estimate of 10% in generic SNe. However, this result is highly dependent on the assumed geometry of the circumstellar medium, and could be relaxed back to 10% by challenging spherical symmetry. Consequently, a more sophisticated, inhomogeneous characterisation of the shock and the progenitor’s environment is required before establishing whether or not Type II SNe are indeed efficient CR accelerators at early times.
Shapes of dark matter haloes with discrete globular cluster dynamics: The example of NGC 5128 (Centaurus A)
Authors: Veršič T. , Rejkuba M. , Arnaboldi M. , Gerhard O. , Pulsoni C. , Valenzuela L. M. , Hartke J. , Watkins L. L. , van de Ven G. , Thater S. 
Published: April 2024

Context.Within the Λ cold dark matter (ΛCDM) cosmology, dark matter haloes are expected to deviate from spherical symmetry. The particular shape of a galactic halo reflects the environment and mass assembly history of its host, as well as the nature of dark matter. Constraining halo shapes at large galactocentric distances is challenging because of the low density of luminous tracers. The well-studied massive early-type galaxy NGC 5128, also known as Centaurus A (Cen A), has a large number of radial velocity measurements for globular clusters (GCs) and planetary nebulae (PNe) extending over a vast area of its extended low-surface-brightness stellar halo.Aims.In this work, we aim to determine the deviation from spherical symmetry of the dark matter halo of Cen A at 5Reusing its GCs as kinematic tracers of the gravitational potential.Methods.We investigated the largest photometric catalogue of GC candidates in order to accurately characterise the spatial distribution of the relaxed population of GCs. To investigate the presence of non-relaxed structures in the kinematic catalogue of GCs, we used the relaxed point-symmetric velocity field as determined by the host’s PNe population. We used anisotropic Jeans modelling under axisymmetric assumptions together with the Gaussian likelihood and GCs as discrete tracers. The gravitational potential is generated by flattened stellar and dark matter distributions. We leveraged the different orbital properties of the blue and red GCs – such as rotation and velocity anisotropy – to model both populations separately. By minimisingχ2, we iteratively find the best-fit parameters.Results.We find that the discrete kinematics of the GCs are consistent with being drawn from an underlying relaxed velocity field determined from PNe. The best-fit parameters of the gravitational potential recovered from the blue and red GCs separately agree well and we use them to compute the final results:M200 = 1.86−0.691.61 × 1012 M⊙,M⋆/LB = 2.98−0.78+0.96, and the flatteningqDM = 1.45−0.53+0.78. Both GC populations show mild rotation, with red having a slightly stronger rotational signature and radially biased orbits, and blue GCs preferring negative velocity anisotropy.Conclusions.An oblate or a spherical dark matter halo of NGC 5128 is strongly disfavoured by our modelling.
Improving the spatial resolution of solar images using super-resolution diffusion generative adversarial networks
Authors: Song Wei , Ma Ying , Sun Haoying , Zhao Xiaobing , Lin Ganghua 
Published: April 2024

Context. High-spatial-resolution solar images contribute to the study of small-scale structures on the Sun. The Helioseismic and Magnetic Imager (HMI) conducts continuous full-disk observations of the Sun at a fixed cadence, accumulating a wealth of observational data. However, the spatial resolution of HMI images is not sufficient to analyze the small-scale structures of solar activity.
Aims. We present a new super-resolution (SR) method based on generative adversarial networks (GANs) and denoising diffusion probabilistic models (DDPMs) that can increase the spatial resolution of HMI images by a factor four.
Methods. We propose a method called super-resolution diffusion GANs (SDGAN), which combines GANs and DDPMs for the SR reconstruction of HMI images. SDGAN progressively maps low-resolution (LR) images to high-resolution (HR) images through a conditional denoising process. It employs conditional GANs to simulate the denoising distribution and optimizes model results using nonsaturating adversarial loss and perceptual loss. This approach enables fast and high-quality reconstruction of solar images.
Results. We used high-spatial-resolution images from the Goode Solar Telescope (GST) as HR images and created a data set consisting of paired images from HMI and GST. We then used this data set to train SDGAN for the purpose of reconstructing HMI images with four times the original spatial resolution. The experimental results demonstrate that SDGAN can obtain high-quality HMI reconstructed images with just four denoising steps.
Black hole outflows initiated by a large-scale magnetic field
Authors: James Bestin , Janiuk Agnieszka , Karas Vladimír 
Published: April 2024

Context. Accreting black hole sources show variable outflows at different mass scales. For instance, in the case of galactic nuclei, our own Galactic center Sgr A* exhibits flares and outbursts in the X-ray and infrared bands. Recent studies suggest that the inner magnetospheres of these sources have a pronounced effect on these emissions.
Aims. Accreting plasma carries the frozen-in magnetic flux along with it down to the black hole horizon. During the infall, the magnetic field intensifies, and this can lead to a magnetically arrested state. We investigate the competing effects of inflows at the black hole horizon and the outflows that develop in the accreting plasma through the action of the magnetic field in the inner magnetosphere, and we determine the implications of these effects.
Methods. We started with a spherically symmetric Bondi-type inflow and introduced a magnetic field. In order to understand the influence of the initial configuration, we started the computations with an aligned magnetic field with respect to the rotation axis of the black hole. Then we proceeded to the case of magnetic fields that are inclined to the rotation axis of the black hole. We employed the 2D and 3D versions of the code HARM for the aligned field models and used the 3D version for the inclined field. We compared the results of computations with each other.
Results. We observe that the magnetic lines of force start to accrete with the plasma while an equatorial intermittent outflow develops. This outflow continues to push some material away from the black hole in the equatorial plane, while some other material is ejected in the vertical direction from the plane. In consequence, the accretion rate fluctuates as well. The direction of the black hole spin prevails at later stages. It determines the flow geometry near the event horizon. On larger scales, however, the flow geometry remains influenced by the initial inclination of the field.
An isotropic full-sky sample of optically selected blazars
Authors: Kudenko Maria , Troitsky Sergey 
Published: April 2024

Context. Various high-energy phenomena in the Universe are associated with blazars, which are powerful active galaxies with jets pointing at the observer. Novel results relating blazars to high-energy neutrinos, cosmic rays, and even possible manifestations of new particle physics, often emerge from statistical analyses of blazar samples, and uniform sky coverage is important for many of these studies.
Aims. Here, we construct a uniform full-sky catalog of blazars selected by their optical emission.
Methods. We defined the criteria of isotropy, making a special effort to cover the Galactic plane region, and compiled an isotropic sample of blazars with Gaia optical magnitudes of G < 18m, corrected for Galactic absorption. The sources were taken from full-sky samples selected by parsec-scale radio emission or by high-energy gamma-ray flux, both of which are known to efficiently select blazar-like objects.
Results. We present a catalog of 651 optically bright blazars, uniformly distributed in the sky, together with their radio, optical, X-ray, and gamma-ray fluxes, and an isotropic sample of 336 confirmed BL Lac type objects.
Conclusions. This catalog may be used in future statistical studies of energetic neutrinos, cosmic rays, and gamma rays.
PDRs4All
Authors: Fuente Asunción , Roueff Evelyne , Le Petit Franck , Le Bourlot Jacques , Bron Emeric , Wolfire Mark G. , Babb James F. , Yan Pei-Gen , Onaka Takashi , Black John H. , Schroetter Ilane , Van De Putte Dries , Sidhu Ameek , Canin Amélie , Trahin Boris , Alarcón Felipe , Chown Ryan , Kannavou Olga , Berné Olivier , Habart Emilie , Peeters Els , Goicoechea Javier R. , Zannese Marion , Meshaka Raphael , Okada Yoko , Röllig Markus , Le Gal Romane , Sales Dinalva A. , Palumbo Maria Elisabetta , Baratta Giuseppe Antonio , Madden Suzanne C. , Neelamkodan Naslim , Zhang Ziwei E. , Stancil P. C. 
Published: April 2024

Context. One of the main problems in astrochemistry is determining the amount of sulfur in volatiles and refractories in the interstellar medium. The detection of the main sulfur reservoirs (icy H2S and atomic gas) has been challenging, and estimates are based on the reliability of models to account for the abundances of species containing less than 1% of the total sulfur. The high sensitivity of the James Webb Space Telescope provides an unprecedented opportunity to estimate the sulfur abundance through the observation of the [S I] 25.249 µm line.
Aims. Our aim is to determine the amount of sulfur in the ionized and warm molecular phases toward the Orion Bar as a template to investigate sulfur depletion in the transition between the ionized gas and the molecular cloud in HII regions.
Methods. We used the [S III] 18.7 µm, [S IV] 10.5 µm, and [S l] 25.249 µm lines to estimate the amount of sulfur in the ionized and molecular gas along the Orion Bar. For the theoretical part, we used an upgraded version of the Meudon photodissociation region (PDR) code to model the observations. New inelastic collision rates of neutral atomic sulfur with ortho-and para- molecular hydrogen were calculated to predict the line intensities.
Results. The [S III] 18.7 µm and [S IV] 10.5 µm lines are detected over the imaged region with a shallow increase (by a factor of 4) toward the HII region. This suggests that their emissions are partially coming from the Orion Veil. We estimate a moderate sulfur depletion, by a factor of ~2, in the ionized gas. The corrugated interface between the molecular and atomic phases gives rise to several edge-on dissociation fronts we refer to as DF1, DF2, and DF3. The [S l] 25.249 µm line is only detected toward DF2 and DF3, the dissociation fronts located farthest from the HII region. This is the first ever detection of the [S l] 25.249 µm line in a PDR. The detailed modeling of DF3 using the Meudon PDR code shows that the emission of the [S l] 25.249 µm line is coming from warm (>40 K) molecular gas located at AV ~1–5 mag from the ionization front. Moreover, the intensity of the [S l] 25.249 µm line is only accounted for if we assume the presence of undepleted sulfur.
Conclusions. Our data show that sulfur remains undepleted along the ionic, atomic, and molecular gas in the Orion Bar. This is consistent with recent findings that suggest that sulfur depletion is low in massive star-forming regions because of the interaction of the UV photons coming from the newly formed stars with the interstellar matter.
Resistively controlled primordial magnetic turbulence decay
Authors: Brandenburg A. , Neronov A. , Vazza F. 
Published: April 2024

Context. Magnetic fields generated in the early Universe undergo turbulent decay during the radiation-dominated era. The decay is governed by a decay exponent and a decay time. It has been argued that the latter is prolonged by magnetic reconnection, which depends on the microphysical resistivity and viscosity. Turbulence, on the other hand, is not usually expected to be sensitive to microphysical dissipation, which affects only very small scales.
Aims. We want to test and quantify the reconnection hypothesis in decaying hydromagnetic turbulence.
Methods. We performed high-resolution numerical simulations with zero net magnetic helicity using the PENCIL CODE with up to 20483 mesh points and relate the decay time to the Alfvén time for different resistivities and viscosities.
Results. The decay time is found to be longer than the Alfvén time by a factor that increases with increasing Lundquist number to the 1/4 power. The decay exponent is as expected from the conservation of the Hosking integral, but a timescale dependence on resistivity is unusual for developed turbulence and not found for hydrodynamic turbulence. In two dimensions, the Lundquist number dependence is shown to be leveling off above values of ≈25 000, independently of the value of the viscosity.
Conclusions. Our numerical results suggest that resistivity effects have been overestimated in earlier work. Instead of reconnection, it may be the magnetic helicity density in smaller patches that is responsible for the resistively slow decay. The leveling off at large Lundquist number cannot currently be confirmed in three dimensions.
Large-field CO (J= 1−0) observations toward SNR G150.3+4.5
Authors: Feng Jian-Cheng , Chen Xuepeng , Su Yang , Sun Li , Zhang Shiyu , Zhou Xin , Guo Weihua 
Published: April 2024

Aims. We aim to investigate the molecular environment of the supernova remnant (SNR) G150.3+4.5, and explore its association with ambient molecular clouds (MCs).Methods. We present large-field CO (J= 1−0) molecular line observations toward SNR G150.3+4.5, using the 13.7 m millimeter telescope of the Purple Mountain Observatory. The observations have an angular resolution of ~55″. We analyzed the spatial distribution of MCs in relation to the SNR shell detected in previous Urumqiλ6 cm radio observations and examined the CO spectra for kinematics information.Results. We find that MCs within the velocity range of [−14, −2] km s−1are spatially distributed along the radio shell of the SNR. Line broadening and asymmetries are observed in the CO spectra of the clouds. Moreover, we find that the molecular clouds around the shell have systematic velocity gradients in the position–velocity (PV) diagram. Both the morphology alignment and gas kinematics suggest that the SNR is associated with the ambient MCs at ~740 pc. Based on the CO gas distance, the dimension and the age of the SNR are estimated to be 40 pc × 33 pc and 3.8 × 104yr, respectively. The very high energy emission of 1LHAASO J0428+5531 toward the SNR may originate from the interaction between the SNR and the surrounding MCs.
The jet of BP Tau
Authors: Dodin A. V. , Potanin S. A. , Burlak M. A. , Cheryasov D. V. , Ikonnikova N. P. , Lamzin S. A. , Safonov B. S. , Shatskii N. I. , Tatarnikov A. M. 
Published: April 2024

Context. A strong global magnetic field of young low-mass stars and a high accretion rate are the necessary conditions for the formation of collimated outflows (jets) from these objects. But it is still unclear whether these conditions are also sufficient.
Aims. We aim to check whether BP Tau, an actively accreting young star with a strong magnetic field, has a jet.
Methods. We carried out narrowband [S II] 672 nm imaging and spectroscopic observations of BP Tau and its vicinity.
Results. We find that BP Tau is a source of a Herbig-Haro flow (assigned number HH 1181), which includes two HH objects moving from the star in opposite directions and a micro- (counter-) jet of ∼1″ projected length. The flow is oriented along position angle 59 ± 1°.
Probing the eccentricity in protostellar discs: Modelling kinematics and morphologies
Authors: Ragusa Enrico , Lynch Elliot , Laibe Guillaume , Longarini Cristiano , Ceppi Simone 
Published: April 2024

Context. Protostellar discs are mostly modelled as circular structures of gas and dust orbiting a protostar. However, a number of physical mechanisms, for example, the presence of a (sub)stellar companion or initial axial asymmetry, can cause the gas and dust orbital motion to become eccentric. Theoretical studies have revealed that, when present, disc eccentricity is expected to occur with predictable profiles that can be long-lasting and potentially observable in protostellar systems.
Aims. We construct an analytical model predicting the typical features of the kinematics and morphology of eccentric protostellar discs, with the final goal of characterising the observational appearance of eccentricity in discs.
Methods. We validate the model using a numerical simulation of a circumbinary disc (where the binary makes the disc eccentric). We finally post-process the simulation with Monte Carlo radiative transfer to study how eccentric features would appear through the ‘eyes’ of ALMA.
Results. Besides the motion of the material on eccentric Keplerian orbits in the disc orbital plane, the most characteristic eccentric feature emerging from the analytical model is strong vertical motion with a typical anti-symmetric pattern (with respect to the disc line of pericentres). A circumbinary disc with a ≈ 40 au eccentric cavity (ecav = 0.2), carved by an abin = 15 au binary, placed at a distance d = 130 pc, is expected to host in its upper emission surface vertical oscillations up to vz ~ 400 m s−1 close to the cavity edge, that is to say, well within ALMA spectral and spatial resolution capabilities. A residual spiral pattern in the vertical velocity Δvz ~ 150 m s−1 of the simulation cannot be captured by the theoretical model, we speculate it to be possibly linked to the presence of a companion in the system.
Recovering the gas properties of protoplanetary disks through parametric visibility modeling: MHO 6
Authors: Kurtovic N. T. , Pinilla P. 
Published: April 2024

Context. The composition and distribution of the gas in a protoplanetary disk plays a key role in shaping the outcome of the planet formation process. Observationally, the recovery of information such as the emission height and brightness temperature from interfer-ometric data is often limited by the imaging processes.
Aims. To overcome the limitations of image-reconstruction when analyzing gas emission from interferometric observations, we have introduced a parametric model to fit the main observable properties of the gaseous disk component in the visibility plane. This approach is also known as parametric visibility modeling.
Methods. We applied our parametric visibility modeling to the gas brightness distribution of the molecular line emission from 12CO J = 3–2 and 13CO J = 3–2 in the disk around MHO 6, a very-low-mass star in the Taurus star-forming Region. To improve the flux fidelity of our parametric models, we combined models with different pixel resolution before the computation of their visibilities, referred to as “nesting images.”
Results. When we apply our parametric visibility modeling to MHO 6, with independent fits to the emission from its CO isopoto-logues, the models return the same consistent results for the stellar mass, disk geometry, and central velocity. The surface height and brightness temperature distribution are also recovered. When compared to other disks, MHO 6 surface height is among the most elevated surfaces, consistent with the predictions for disks around very-low-mass stars.
Conclusions. This work demonstrates the feasibility of running rapidly iterable parametric visibility models in moderate resolution and sensitivity interferometric observations. More importantly, this methodology opens the analysis of disk’s gas morphology to observations where image-based techniques are unable to robustly operate, as in the case of the compact disk around MHO 6.
Expatriates’ boundary-spanning: double-edged effects in multinational enterprises
Authors: Liu Ting , Sekiguchi Tomoki , Qin Jiayin , Shen Ya Xi 
Published: April 2024

Abstract
Expatriates typically perform boundary-spanning to address challenges related to functional, linguistic, and cultural variations within multinational enterprises (MNEs), which in turn influences their relationships with host-country employees. Integrating social capital and role theory perspectives, this study explores the relational dynamics between expatriates and host-country employees by developing a novel theoretical framework that examines the double-edged effects of expatriates’ boundary-spanning. We propose that expatriates’ boundary-spanning nurtures mutual trust between expatriates and host-country employees, further facilitating expatriates’ identification with subsidiaries and host-country employees’ identification with MNEs. On the other hand, we propose that boundary-spanning increases expatriates’ role stressors, causing expatriates’ emotional exhaustion and outgroup categorization by host-country employees. We further categorize expatriates’ boundary-spanning into three types (functional, linguistic, and cultural) and theorize about their varying effects on the cognitive and affective bases of mutual trust and on role stressors. With data from 177 expatriate–host-country coworker dyads in Chinese MNEs, our double-edged framework is generally supported. Our findings suggest that cultural boundary-spanning exhibits the strongest double-edged effect, while functional boundary-spanning shows asymmetric effects, with negative outcomes surpassing positive ones, and linguistic boundary-spanning demonstrates the weakest effect. This study offers realistic and comprehensive insights into expatriates’ boundary-spanning, particularly in expatriate–host-country employee relationships.