bluuebunny/crossref_metadata_2025 huggingface dataset:
Confronting Taboo Topics in Communication Sciences and Disorders: How Conversations Can Uncover Cultural Blind Spots
Authors: Tyson Cara E. , Núñez Giselle
Published: April 2024

Purpose:

An increase in social justice movements has renewed the focus on topics surrounding diversity, equity, and inclusion (DEI) in the speech, language, and hearing sciences. For example, the American Speech-Language-Hearing Association publicly renewed its commitment to advance DEI initiatives. This commitment includes restructuring the certification maintenance standards around these initiatives and the standards of graduate education on cultural responsiveness. Despite these requirements, there remains a slow movement toward impactful and sustainable changes. One explanation is the hesitation to engage in conversations that are difficult and often considered taboo.

Conclusion:

This article aims to discuss taboo topics in communication sciences and disorders related to race and racism, privilege, and support through allyship.
Characterising X-ray variability in light curves with complex sampling patterns: Application to the eROSITA south ecliptic pole survey
Authors: Bogensberger D. , Nandra K. , Buchner J.
Published: April 2024

Aims. During its all-sky survey phase, the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) spacecraft scans through the ecliptic poles every 4 h. This extensive data set of long-duration, frequent, and consistent observations of thousands of X-ray sources is ideal for a detailed long-term X-ray-variability analysis. However, individual observations are short, are separated by long but consistent gaps, and have varying exposure times. Therefore, the identification of variable sources and the characterisation and quantification of their variability requires a unique methodology. We aim to develop and evaluate variability analysis methods for eROSITA observations, focusing on sources close to the survey poles. We also aim to detect intrinsically variable sources at any count rate and quantify the variability of low-count-rate sources.

Methods. We simulate eROSITA-like light curves to evaluate and quantify the effect of survey mode observations on the measured periodogram and normalised excess variance. We introduce a new method for estimating the normalised intrinsic variance of a source based on the Bayesian excess variance (bexvar) method.

Results. We determine thresholds for identifying likely variable sources while minimising the false-positive rate, as a function of the number of bins, and the average count rate in the light curve. The bexvar normalised intrinsic variance estimate is significantly more accurate than the normalised excess variance method in the Poisson regime. At high count rates, the two methods are comparable. We quantify the scatter in the intrinsic variance of a stationary pink-noise process, and investigate how to reduce it. Finally, we determine a description of the excess noise in a periodogram caused by varying exposure times throughout a light curve. Although most of these methods were developed specifically for analysing variable active galactic nuclei in the eROSITA all-sky survey, they can also be used for the variability analysis of other datasets from other telescopes, with slight modifications.
Cosmology with galaxy cluster properties using machine learning
Authors: Qiu Lanlan , Napolitano Nicola R. , Borgani Stefano , Zhong Fucheng , Li Xiaodong , Radovich Mario , Lin Weipeng , Dolag Klaus , Tortora Crescenzo , Wang Yang , Remus Rhea-Silvia , Wu Sirui , Longo Giuseppe
Published: April 2024

Context. Galaxy clusters are the largest gravitating structures in the universe, and their mass assembly is sensitive to the underlying cosmology. Their mass function, baryon fraction, and mass distribution have been used to infer cosmological parameters despite the presence of systematics. However, the complexity of the scaling relations among galaxy cluster properties has never been fully exploited, limiting their potential as a cosmological probe.

Aims. We propose the first machine learning (ML) method using galaxy cluster properties from hydrodynamical simulations in different cosmologies to predict cosmological parameters combining a series of canonical cluster observables, such as gas mass, gas bolometric luminosity, gas temperature, stellar mass, cluster radius, total mass, and velocity dispersion at different redshifts.

Methods. The ML model was trained on mock “measurements” of these observable quantities from Magneticum multi-cosmology simulations to derive unbiased constraints on a set of cosmological parameters. These include the mass density parameter, Ωm, the power spectrum normalization,σ8, the baryonic density parameter, Ωb, and the reduced Hubble constant,h0.

Results. We tested the ML model on catalogs of a few hundred clusters taken, in turn, from each simulation and found that the ML model can correctly predict the cosmology from where they have been picked. The cumulative accuracy depends on the cosmology, ranging from 21% to 75%. We demonstrate that this is sufficient to derive unbiased constraints on the main cosmological parameters with errors on the order of ~14% for Ωm, ~8% forσ8, ~6% for Ωb, and ~3% forh0.

Conclusions. This proof-of-concept analysis, though based on a limited variety of multi-cosmology simulations, shows that ML can efficiently map the correlations in the multidimensional space of the observed quantities to the cosmological parameter space and narrow down the probability that a given sample belongs to a given cosmological parameter combination. More large-volume, mid-resolution, multi-cosmology hydro-simulations need to be produced to expand the applicability to a wider cosmological parameter range. However, this first test is exceptionally promising, as it shows that these ML tools can be applied to cluster samples from multiwavelength observations from surveys such asRubin/LSST, CSST,Euclid, andRomanin optical and near-infrared bands, and eROSITA in X-rays, to the constrain cosmology and effect of baryonic feedback.
Identifying frequency de-correlated dust residuals in B-mode maps by exploiting the spectral capability of bolometric interferometry
Authors: Regnier M. , Manzan E. , Hamilton J.-Ch. , Mennella A. , Errard J. , Zapelli L. , Torchinsky S. A. , Paradiso S. , Battistelli E. , De Bernardis P. , Colombo L. , De Petris M. , D’Alessandro G. , Garcia B. , Gervasi M. , Masi S. , Mousset L. , Miron Granese N. , O’Sullivan C. , Piat M. , Rasztocky E. , Romero G. E. , Scoccola C. G. , Zannoni M.
Published: April 2024

Context. Astrophysical polarized foregrounds represent the most critical challenge in cosmic microwave background (CMB) B-mode experiments, requiring multifrequency observations to constrain astrophysical foregrounds and isolate the CMB signal. However, recent observations indicate that foreground emission may be more complex than anticipated. Not properly accounting for these complexities during component separation can lead to a bias in the recovered tensor-to-scalar ratio.

Aims. In this paper we investigate how the increased spectral resolution provided by band-splitting in bolometric interferometry (BI) through a technique called spectral imaging can help control the foreground contamination in the case of an unaccounted-for Galactic dust frequency de-correlation along the line of sight (LOS).

Methods. We focused on the next-generation ground-based CMB experiment CMB-S4 and compared its anticipated sensitivity, frequency, and sky coverage with a hypothetical version of the same experiment based on BI (CMB-S4/BI). We performed a Monte Carlo analysis based on parametric component separation methods (FGBuster and Commander) and computed the likelihood of the recovered tensor-to-scalar ratio, r.

Results. The main result is that spectral imaging allows us to detect systematic uncertainties on r from frequency de-correlation when this effect is not accounted for in the component separation. Conversely, an imager such as CMB-S4 would detect a biased value of r and would be unable to spot the presence of a systematic effect. We find a similar result in the reconstruction of the dust spectral index, and we show that with BI we can more precisely measure the dust spectral index when frequency de-correlation is present and not accounted for in the component separation.

Conclusions. The in-band frequency resolution provided by BI allows us to identify dust LOS frequency de-correlation residuals where an imager with a similar level of performance would fail. This creates the possibility of exploiting this potential in the context of future CMB polarization experiments that will be challenged by complex foregrounds in their quest for B-mode detection.
Extremely metal-poor stars in the Fornax and Carina dwarf spheroidal galaxies
Authors: Lucchesi R. , Jablonka P. , Skúladóttir Á. , Lardo C. , Mashonkina L. , Primas F. , Venn K. , Hill V. , Minniti D.
Published: April 2024

We present our analysis of VLT/UVES and X-shooter observations of six very metal-poor stars, including four stars at [Fe/H] ≈ −3 in the Fornax and Carina dwarf spheroidal (dSph) galaxies. To date, this metallicity range in these two galaxies has not yet been investigated fully, or at all in some cases. The chemical abundances of 25 elements are presented, based on 1D and local thermodynamic equilibrium (LTE) model atmospheres. We discuss the different elemental groups, and find thatα- and iron-peak elements in these two systems are generally in good agreement with the Milky Way halo at the same metallicity. Our analysis reveals that none of the six stars we studied exhibits carbon enhancement, which is noteworthy given the prevalence of carbon-enhanced metal-poor stars withouts-process enhancement (CEMP-no) in the Galaxy at similarly low metallicities. Our compilation of literature data shows that the fraction of CEMP-no stars in dSph galaxies is significantly lower than in the Milky Way, and than in ultra-faint dwarf galaxies. Furthermore, we report the discovery of the lowest metallicity, [Fe/H] = −2.92,r-process rich (r-I) star in a dSph galaxy. This star, fnx_06_019, has [Eu/Fe] = +0.8, and also shows enhancement of La, Nd, and Dy, [X/Fe] > +0.5. Our new data in Carina and Fornax help populate the extremely low metallicity range in dSph galaxies, and add to the evidence of a low fraction of CEMP-no stars in these systems.
Equilibrium tides and magnetic activity in stars with close-by massive planets
Authors: Lanza A. F. , Breton S. N.
Published: April 2024

Aims. WASP-18 is an F6V star that hosts a planet with a mass of ~10 Jupiter masses and an orbital period of ~0.94 days. In spite of its relatively fast rotation and young age, the star remains undetected in X-rays, thus implying a very low level of magnetic activity. To account for such unexpected properties, we propose a mechanism that modifies the internal stratification and the photospheric magnetic activity of a late-type main sequence star with a close-by massive planet based on the action of the equilibrium tide.

Methods. We speculate that the horizontal flow produced by the equilibrium tide may interact with the convective plumes in the overshoot layer below the stellar outer convective envelope. The interaction is characterised by a very high Reynolds number (Re ~ 1010), leading to the development of turbulent boundary layers at the surface of such structures, whereas turbulent wakes extend over most of the overshoot layer that they straddle.

Results. We propose that such a tidally induced turbulence can lead to a reduction of the filling factor of the downdrafts in the overshoot layer. As a consequence, the absolute value of the sub-adiabatic gradient increases in that layer hindering the emergence of magnetic flux tubes responsible for the formation of photospheric starspots. We conjecture that this process is occurring in WASP-18, thus providing a possible mechanism to account for the very low level of magnetic activity observed for such a planet host.
Integral field spectroscopy supports atmospheric optics to reveal the finite outer scale of the turbulence
Authors: García-Lorenzo B. , Esparza-Arredondo D. , Acosta-Pulido J. A. , Castro-Almazán J. A.
Published: April 2024

Context. The spatial coherence wavefront outer scale (ℒ0) characterizes the size of the largest turbulence eddies in Earth’s atmosphere, determining low spatial frequency perturbations in the wavefront of the light captured by ground-based telescopes. Advances in adaptive optics (AO) techniques designed to compensate for atmospheric turbulence emphasize the crucial role of this parameter for the next generation of large telescopes.

Aims. The motivation of this work is to introduce a novel technique for estimating ℒ0 from seeing-limited integral field spectroscopic (IFS) data. This approach is based on the impact of a finite ℒ0 on the light collected by the pupil entrance of a ground-based telescope.

Methods. We take advantage of the homogeneity of IFS observations to generate band filter images spanning a wide wavelength range, enabling the assessment of image quality (IQ) at the telescope’s focal plane. Comparing the measured wavelength-dependent IQ variation with predictions derived from a first-order analytical approach based on turbulence statistics simplifications using the von Kármán model provides valuable insights into the prevailing ℒ0 parameter during the observations. We applied the proposed technique to observations from the Multi-Unit Spectroscopic Explorer (MUSE) in the wide-field mode obtained at the Paranal Observatory.

Results. Our analysis successfully validates the first-order analytical expression, which combines the seeing (ε0) and the ℒ0 parameters, to predict the IQ variations with the wavelength in ground-based astronomical data. However, we observed some discrepancies between the measured and predictions of the IQ that are analyzed in terms of uncertainties in the estimated ε0 and dome-induced turbulence contributions.

Conclusions. This work constitutes the empirical validation of the analytical expression for estimating IQ at the focal plane of ground-based telescopes under specific ε0 and finite ℒ0 conditions. Additionally, we provide a simple methodology to characterize the ℒ0 and dome-seeing (εdome) as by-products of IFS observations routinely conducted at major ground-based astronomical observatories.
Multi-messenger prospects for black hole – neutron star mergers in the O4 and O5 runs
Authors: Colombo Alberto , Duqué Raphaël , Salafia Om Sharan , Broekgaarden Floor S. , Iacovelli Francesco , Mancarella Michele , Andreoni Igor , Gabrielli Francesco , Ragosta Fabio , Ghirlanda Giancarlo , Fragos Tassos , Levan Andrew J. , Piranomonte Silvia , Melandri Andrea , Giacomazzo Bruno , Colpi Monica
Published: April 2024

The existence of merging black hole-neutron star (BHNS) binaries has been ascertained through the observation of their gravitational wave (GW) signals. However, to date, no definitive electromagnetic (EM) emission has been confidently associated with these mergers. Such an association could help unravel crucial information on these systems, for example, their BH spin distribution, the equation of state (EoS) of the neutron star and the rate of heavy element production. We modeled the multi-messenger (MM) emission from BHNS mergers detectable during the fourth (O4) and fifth (O5) observing runs of the LIGO-Virgo-KAGRA (LVK) GW detector network in order to provide detailed predictions that can help enhance the effectiveness of observational efforts and extract the highest possible scientific information from such remarkable events. Our methodology is based on a population synthesis approach, which includes the modeling of the signal-to-noise ratio of the GW signal in the detectors, the GW-inferred sky localization of the source, the kilonova (KN) optical and near-infrared light curves, the relativistic jet gamma-ray burst (GRB) prompt emission peak photon flux, and the GRB afterglow light curves in the radio, optical, and X-ray bands. The resulting prospects for BHNS MM detections during O4 are not promising, with an LVK GW detection rate of 15.0−8.8+15.4 yr−1, but joint MM rates of ∼10−1 yr−1 for the KN and ∼10−2 yr−1 for the jet-related emission. In O5, we found an overall increase in expected detection rates by around an order of magnitude, owing to both the enhanced sensitivity of the GW detector network and the coming online of future EM facilities. Considering variations in the NS EoS and BH spin distribution, we find that the detection rates can increase further by up to a factor of several tens. Finally, we discuss direct searches for the GRB radio afterglow with large field-of-view instruments during O5 and beyond as a new possible follow-up strategy in the context of ever-dimming prospects for KN detection due to the recession of the GW horizon.
The winding number of coronal flux ropes
Authors: Price D. J. , Pomoell J. , Kilpua E. K. J.
Published: April 2024

Context. Magnetic flux ropes are key structures in solar and solar-terrestrial research. Their magnetic twist is an important quantity for understanding their eruptivity, their evolution in interplanetary space, and their consequences for planetary space environments. The magnetic twist is expressed in terms of a winding number that describes how many times a field line winds about the axis of the flux rope (FR). Due to the complexity of calculating the winding number, current methods rely largely on its approximation.

Aims. We use a data-driven simulated FR to investigate the winding number Tg in comparison to the commonly used twist proxy Tw, which describes a winding of two infinitesimally close field lines. We also estimate the magnetic flux enclosed in the resultant FR(s).

Methods. We use the magnetic field analysis tools (MAFIAT) software to compute Tg and Tw for data-driven time-dependent magnetofrictional modelling of AR12473.

Results. We find that the FR boundaries can significantly differ depending on whether they are defined using the twist approximation Tw or the winding number Tg. This also significantly affects the FR structure and the estimates of the enclosed magnetic flux. For the event analysed here, Tg also reveals that the twisted flux system consists of two separate intertwined FRs.

Conclusions. The results of this study suggest that the computation of the winding number (Tg) is important for investigations of solar FRs.
Probing star formation rates and histories in AGN and non-AGN galaxies across diverse cosmic environments and X-ray luminosity ranges
Authors: Mountrichas G. , Siudek M. , Cucciati O.
Published: April 2024

In this work, we compare the star formation rates (SFRs) and star formation histories (SFHs) of active galactic nucleus (AGN) and non-AGN galaxies. We explore these aspects across different density fields and over three orders of magnitude in X-ray luminosity (LX). For that purpose, we employed X-ray AGNs detected in the XMM-XXL field and constructed a galaxy control sample, using sources from the VIPERS catalogue. We applied strict photometric and quality selection criteria to ensure that only sources with robust (host) galaxy measurements were included in the analysis. Our final samples consist of 149 X-ray AGNs with 42 < log,[LX,2#x2212;10 keV (erg s−1)] < 45 and 3488 non-AGN systems. The sources span a redshift range of 0.5 < z < 1.0 and have stellar masses within, 10.5 < log [M*(M⊙)] < 11.5. For these systems, we adopted the available measurements for their local densities and their spectral lines (Dn4000) from the VIPERS catalogue. To compare the SFRs of these two populations, we calculated the SFRnorm parameter. The latter is defined as the ratio of the SFRs of AGNs to the SFRs of non-AGN galaxies with similar M* and redshift. Our findings reveal that low- and moderate-LX AGNs (42 < log,[LX,2#x2212;10 keV (erg s−1)] < 44) that reside in low-density fields have a nearly flat SFRnorm-LX relation. In contrast, the AGNs of similar LX values that reside in high-density environments present an increase in SFRnorm with LX. These results are in line with previous studies. Notably, our results suggest that the most luminous of the AGNs (log,[LX,2#x2212;10 keV (erg s−1)] > 44) exhibit an increased SFR in comparison to non-AGN galaxies. This trend appears to be independent of the density of the environment. Furthermore, for AGNs with similar LX, those in high-density regions tend to have higher SFRnorm values compared to their counterparts in low-density areas. Comparisons of the Dn4000 spectral index, which serves as a proxy for the age of the stellar population, reveals that low- and moderate-LX AGNs reside in galaxies with comparable stellar populations with non-AGN systems, regardless of the density field they are situated in. However, the most luminous X-ray sources tend to reside in galaxies that have younger stellar populations, as compared to non-AGN galaxies, regardless of the galaxy’s environment.
Secondary cosmic-ray nuclei in the Galactic halo model with nonlinear Landau damping
Authors: Chernyshov D. O. , Ivlev A. V. , Dogiel V. A.
Published: April 2024

We employed our recent model of the cosmic-ray (CR) halo to compute the Galactic spectra of stable and unstable secondary nuclei. In this model, confinement of the Galactic CRs is entirely determined by the self-generated Alfvénic turbulence whose spectrum is controlled by nonlinear Landau damping. We analyzed the physical parameters affecting propagation characteristics of CRs and estimated the best set of free parameters providing accurate description of available observational data. We also show that agreement with observations at lower energies may be further improved by taking into account the effect of ion-neutral damping that operates near the Galactic disk.
Overstability of the 2:1 mean motion resonance: Exploring disc parameters with hydrodynamic simulations
Authors: Afkanpour Zahra , Ataiee Sareh , Ziampras Alexandros , Penzlin Anna B. T. , Sfair Rafael , Schäfer Christoph , Kley Wilhelm , Schlichting Hilke
Published: April 2024

Context. Resonant planetary migration in protoplanetary discs can lead to an interplay between the resonant interaction of planets and their disc torques called overstability. While theoretical predictions and N-body simulations hinted at its existence, there was no conclusive evidence until hydrodynamical simulations were performed.

Aims. Our primary purpose is to find a hydrodynamic setup that induces overstability in a planetary system with two moderate-mass planets in a first-order 2:1 mean motion resonance. We also aim to analyse the impact of key disc parameters, namely the viscosity, surface density, and aspect ratio, on the occurrence of overstability in this planetary system when the masses of the planets are kept constant.

Methods. We performed 2D locally isothermal hydrodynamical simulations of two planets, with masses of 5 and 10 M⊕, in a 2:1 resonance. Upon identifying the fiducial model in which the system exhibits overstability, we performed simulations with different disc parameters to explore the effects of the disc on the overstability of the system.

Results. We observe an overstable planetary system in our hydrodynamic simulations. In the parameter study, we note that overstability occurs in discs characterised by low surface density and low viscosity. Increasing the surface density reduces the probability of overstability within the system. A limit cycle was observed in a specific viscous model with αv = 10−3. In almost all our models, planets create partial gaps in the disc, which affects both the migration timescale and structure of the planetary system.

Conclusions. We demonstrate the existence of overstability using hydrodynamic simulations but find deviations from the analytic approximation and show that the main contribution to this deviation can be attributed to dynamic gap opening.
Small-scale magnetic flux emergence preceding a chain of energetic solar atmospheric events
Authors: Nóbrega-Siverio D. , Cabello I. , Bose S. , van der Voort L. H. M. Rouppe , Joshi R. , Froment C. , Henriques V. M. J.
Published: April 2024

Context.Advancements in instrumentation have revealed a multitude of small-scale extreme-ultraviolet (EUV) events in the solar atmosphere and considerable effort is currently undergoing to unravel them.

Aims.Our aim is to employ high-resolution and high-sensitivity magnetograms to gain a detailed understanding of the magnetic origin of such phenomena.

Methods.We used coordinated observations from the Swedish 1-m Solar Telescope (SST), the Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory (SDO) to analyze an ephemeral magnetic flux emergence episode and the following chain of small-scale energetic events. These unique observations clearly link these phenomena together.

Results.The high-resolution (0.″057 pixel−1) magnetograms obtained with SST/CRISP allowed us to reliably measure the magnetic field at the photosphere and to detect the emerging bipole that caused the subsequent eruptive atmospheric events. Notably, this small-scale emergence episode remains indiscernible in the lower resolution SDO/HMI magnetograms (0.″5 pixel−1). We report the appearance of a dark bubble in Ca IIK 3933 Å related to the emerging bipole, a sign of the canonical expanding magnetic dome predicted in flux emergence simulations. Evidence of reconnection are also found, first through an Ellerman bomb and later by the launch of a surge next to a UV burst. The UV burst exhibits a weak EUV counterpart in the coronal SDO/AIA channels. By calculating the differential emission measure (DEM), its plasma is shown to reach a temperature beyond 1 MK and to have densities between the upper chromosphere and transition region.

Conclusions.Our study showcases the importance of high-resolution magnetograms in revealing the mechanisms that trigger phenomena such as EBs, UV bursts, and surges. This could hold implications for small-scale events similar to those recently reported in the EUV using Solar Orbiter. The finding of temperatures beyond 1 MK in the UV burst plasma strongly suggests that we are examining analogous features. Therefore, we recommend caution when drawing conclusions from full-disk magnetograms that lack the necessary resolution to reveal their true magnetic origin.
One-dimensional, geometrically stratified semi-empirical models of the quiet-Sun photosphere and lower chromosphere
Authors: Borrero J. M. , Milić I. , Pastor Yabar A. , Kaithakkal A. J. , de la Cruz Rodríguez J.
Published: April 2024

Context. One-dimensional, semi-empirical models of the solar atmosphere are widely employed in numerous contexts within solar physics, ranging from the determination of element abundances and atomic parameters to studies of the solar irradiance and from Stokes inversions to coronal extrapolations. These models provide the physical parameters (i.e. temperature, gas pressure, etc.) in the solar atmosphere as a function of the continuum optical depth τc. The transformation to the geometrical z scale (i.e. vertical coordinate) is provided via vertical hydrostatic equilibrium.

Aims. Our aim is to provide updated, one-dimensional, semi-empirical models of the solar atmosphere as a function of z, but employing the more general case of three-dimensional magneto-hydrostatic equilibrium (MHS) instead of vertical hydrostatic equilibrium (HE).

Methods. We employed a recently developed Stokes inversion code that, along with non-local thermodynamic equilibrium effects, considers MHS instead of HE. This code is applied to spatially and temporally resolved spectropolarimetric observations of the quiet Sun obtained with the CRISP instrument attached to the Swedish Solar Telescope.

Results. We provide average models for granules, intergranules, dark magnetic elements, and overall quiet-Sun as a function of both τc and z from the photosphere to the lower chromosphere.

Conclusions. We demonstrate that, in these quiet-Sun models, the effect of considering MHS instead of HE is negligible. However, employing MHS increases the consistency of the inversion results before averaging. We surmise that in regions with stronger magnetic fields (i.e. pores, sunspots, network) the benefits of employing the magneto-hydrostatic approximation will be much more palpable.
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.
Asimulation: Domain formation and impact on observables in resolved cosmological simulations of the (a)symmetron
Authors: Christiansen Øyvind , Hassani Farbod , Mota David F.
Published: April 2024

The symmetron is a dark energy and dark matter candidate that forms topological defects in the late-time universe and holds the promise of resolving some of the cosmological tensions. We performed high-resolution simulations of the dynamical and non-linear (a)symmetron using the recently developed relativistic N-body code asevolution. By extensively testing the temporal and spatial convergence of domain decompositioning and domain wall stability, we determined criteria and physical intuition for the convergence. We applied the resolution criteria to run five high-resolution simulations with 12803 grids and a box size of 500 Mpc h−1 of the (a)symmetron. We considered the behaviour of the scalar field and the domain walls in each scenario. We find the effect on the matter power spectra, the HMFs, and observables computed over the past light cone of an observer, such as the integrated Sachs-Wolfe and non-linear Rees-Sciama effect and the lensing, compared to ΛCDM. We show local oscillations of the fifth force strength and the formation of planar structures in the density field. The dynamics of the field was visualised in animations with high resolution in time. The simulation code is made publicly available.
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.
The MODEST catalog of depth-dependent spatially coupled inversions of sunspots observed by Hinode/SOT-SP
Authors: Castellanos Durán J. S. , Milanovic N. , Korpi-Lagg A. , Löptien B. , van Noort M. , Solanki S. K.
Published: April 2024

We present a catalog that contains depth-dependent information about the atmospheric conditions inside sunspot groups of all types. The catalog, which we named MODEST, is currently composed of 944 observations of 117 individual active regions with sunspots and covers all types of features observed in the solar photosphere. We used the SPINOR-2D code to perform spatially coupled inversions of the Stokes profiles observed by Hinode/SOT-SP at high spatial resolution. SPINOR-2D accounts for the unavoidable degradation of the spatial information due to the point spread function of the telescope. The sunspot sample focuses on complex sunspot groups, but simple sunspots are also part of the catalog for completeness. Sunspots were observed from 2006 to 2019, covering parts of solar cycles 23 and 24. The catalog is a living resource, as with time, more sunspot groups will be included.
Cosmography with supernova Refsdal through time-delay cluster lensing: Independent measurements of the Hubble constant and geometry of the Universe
Authors: Grillo C. , Pagano L. , Rosati P. , Suyu S H.
Published: April 2024

We present new measurements of the values of the Hubble constant, matter density, dark energy density, and dark energy density equation-of-state (EoS) parameters. These results have been obtained from a full strong-lensing analysis of the observed positions of 89 multiple images and 4 measured time delays of the supernova (SN) Refsdal in the Hubble Frontier Fields galaxy cluster MACS J1149.5+2223. By strictly following the identical modelling methodology (as done in our previous work undertaken before time delays were available), our cosmographic measurements are essentially blind, based on the frozen procedure. Without using any priors from other cosmological experiments, in an open wCDM cosmological model and via our reference cluster mass model, we measure the following values: H0 = 65.1−3.4+3.5 km s−1 Mpc−1, ΩDE = 0.76−0.10+0.15, and w = −0.92−0.21+0.15 (at the 68.3% confidence level). No other single cosmological probe has been able to simultaneously measure all these parameters. Remarkably, our estimated values of the cosmological parameters, in particular that of H0, are very robust and do not significantly depend on the assumed cosmological model or the cluster mass modelling details. The latter aspect introduces systematic uncertainties on the values of H0 and w, which are found to be largely subdominant compared to the statistical errors. The results of this study demonstrate that the combination of time delays in lens galaxy clusters with extensive photometric and spectroscopic information offers a novel and competitive cosmological tool.