Papers for Monday, Nov 04 2024

New Interferometric Testing Utility (NITU) is a newly developed Python package for analyzing and visualizing interferometric data. It provides Zernike decomposition, interactive visualization, time series analysis, and additional features for optical manufacturing and testing.

This study presents the methodology for creating a cost-efficient radio astronomy telescope that can be used to detect 21 cm emissions (1420.405 MHz) and determine the distribution and kinematics of neutral hydrogen specifically in the Milky Way. By measuring the Doppler shifts of the 21 cm emission, the velocities of hydrogen clouds relative to Earth can be determined. This enables the identification of these clouds' movements, their positions within the galaxy's spiral arms, and their roles in the overall rotational dynamics of the Milky Way. The setup is designed to be accessible to amateurs, enabling others to conduct similar projects. The measurement apparatus consists of a 1-meter parabolic dish, a H1-LNA for 21 cm emissions, an SDR, and a Raspberry Pi. This paper also provides an overview of the data processing required to detect the hydrogen line and generate velocity profiles. Additionally, it examines RFI mitigation techniques, such as spectral filtering and instrument shielding, which enhance observational clarity even in urban environments like Los Angeles. This study also analyzes the observed velocities of different galactic arms, as well as measurements across the sky.

We present TOPO (Time-Ordered Provable Outputs), a tool designed to enhance reproducibility and data integrity in astrophysical research, providing a trustless alternative to data analysis blinding. Astrophysical research frequently involves probabilistic algorithms, high computational demands, and stringent data privacy requirements, making it difficult to guarantee the integrity of results. TOPO provides a secure framework for verifying reproducible data analysis while ensuring sensitive information remains hidden. Our approach utilizes deterministic hashing to generate unique digital fingerprints of outputs, and Merkle Trees to store outputs in a time-ordered manner. This enables efficient verification of specific components or the entire dataset while making it computationally infeasible to manipulate results - thereby mitigating the risk of human interference and confirmation bias, key objectives of blinding methods. We demonstrate TOPO's utility in a cosmological context using TOPO-Cobaya, showcasing how blinding and verification can be seamlessly integrated into Markov Chain Monte Carlo calculations, rendering the process cryptographically provable. This method addresses pressing challenges in the reproducibility crisis and offers a robust, verifiable framework for astrophysical data analysis.

We find statistical evidence for a mismatch between the (global) spatial curvature parameter $K$ in the geodesic equation for incoming photons, and the corresponding parameter in the Friedmann equation that determines the time evolution of the background spacetime and its perturbations. The mismatch hereafter referred to as `curvature-slip' is especially evident when the SH0ES prior on the current expansion rate is assumed. This result is based on joint analyses of cosmic microwave background (CMB) observations with the PLANCK satellite (P18), first year results of the Dark Energy Survey (DES), Baryonic Oscillation (BAO) data, and - at a lower level of significance - also on Pantheon SNIa (SN) catalog. For example, the betting odds against the Null Hypothesis are greater than $10^7$:1, 1400:1 and 1000:1 when P18+SH0ES, P18+DES+SH0ES, and P18+BAO+SH0ES, respectively, are considered. Datasets involving SNIa weaken this curvature slip considerably. Notably, even when the SH0ES prior is not imposed the betting odds for the rejection of the Null Hypothesis are 70:1 and 160:1 in cases where P18+DES and P18+BAO are considered. When the SH0ES prior is imposed, global fit of the modified model (that allows for a nonvanishing `curvature slip') strongly outperforms that of $\Lambda$CDM as is manifested by significant Deviance Information Criterion (DIC) gains, ranging between 7 and 23, depending on the dataset combination considered. Even in comparison to K$\Lambda$CDM the proposed model results in significant, albeit smaller, DIC gains when SN data are excluded. Our finding could possibly be interpreted as an inherent inconsistency between the (idealized) maximally symmetric nature of the FRW metric, and the dynamical evolution of the GR-based homogeneous and isotropic $\Lambda$CDM model (abridged)

The Lyman-$\alpha$ (Lya) line of hydrogen is a well-known tracer of galaxies at high-z. However, the connection between Lya observables and galaxy properties has not fully been established, limiting the use of the line to probe the physics of galaxies. Here, we derive global neutral hydrogen gas (HI) properties of nearby Lya-emitting galaxies to assess the impact of HI on the Lya output of galaxies. We observed 21cm line emission using the VLA in D-array configuration (~55" resolution, ~38 kpc) for 37 star-forming galaxies with available Lya imaging from the Lyman Alpha Reference Samples (LARS and eLARS). We detect 21cm emission for 33/37 galaxies observed. We find no significant correlation of global HI properties with Lya luminosity, escape fraction or equivalent width derived with HST photometry. Additionally, both Lya-emitters and weak or non-emitters are distributed evenly along the HI parameter space of optically-selected z=0 galaxies. Around 74% of the sample is undergoing galaxy interaction, this fraction is higher for Lya-emitters (83% for galaxies with EW$\geq$20Å) than for non or weak emitters (70%). Nevertheless, galaxies identified as interacting have Lya and HI properties statistically consistent with those of non-interacting galaxies. Our results show that global HI properties (on scales > 30kpc) have little direct impact on the Lya output from galaxies. Instead, HI likely regulates Lya emission on small scales: statistical comparisons of Lya and high angular resolution 21cm observations are required to fully assess the role of HI in Lya radiative transfer. While our study indicates that galaxy mergers could play a role in the emission of Lya photons in the local universe, especially for galaxies with high HI fractions, the line-of-sight through which a system is observed ultimately determines Lya observables.

Astrometry from Gaia DR3 has produced a sample of $\sim$170,000 Keplerian orbital solutions, with many more anticipated in the next few years. These data have enormous potential to constrain the population of binary stars, giant planets, and compact objects in the Solar neighborhood. But in order to use the published orbit catalogs for statistical inference, it is necessary to understand their selection function: what is the probability that a binary with a given set of properties ends up in a catalog? We show that such a selection function for the Gaia DR3 astrometric binary catalog can be forward-modeled from the Gaia scanning law, including individual 1D astrometric measurements, the fitting of a cascade of astrometric models, and quality cuts applied in post-processing. We populate a synthetic Milky Way model with binary stars and generate a mock catalog of astrometric orbits. The mock catalog is quite similar to the DR3 astrometric binary sample, suggesting that our selection function is a sensible approximation of reality. Our fitting also produces a sample of spurious astrometric orbits similar to those found in DR3; these are mainly the result of scan angle-dependent astrometric biases in marginally resolved wide binaries. We show that Gaia's sensitivity to astrometric binaries falls off rapidly at high eccentricities, but only weakly at high inclinations. We predict that DR4 will yield $\sim 1$ million astrometric orbits, mostly for bright ($G \lesssim 15$) systems with long periods ($P_{\rm orb} \gtrsim 1000$ d). We provide code to simulate and fit realistic Gaia epoch astrometry for any data release and determine whether any hypothetical binary would receive a cataloged orbital solution.

The cosmological 21-cm signal is sourced from hyperfine transitions in neutral hydrogen atoms. Yet, although hydrogen atoms belong to the sub-class of baryonic matter, it is customary to simplify their treatment and analyze the 21-cm signal as if all the matter in the Universe was in the form of collisionless cold dark matter (CDM). This is usually done by evolving the density field via a scale-independent growth factor (SIGF). In this work, we separate the baryons from CDM and evolve the two species with a proper scale-dependent growth factor (SDGF). By incorporating the SDGF in the 21cmFirstCLASS code, we demonstrate the effect that baryons and CDM have on the 21-cm signal at the linear dark ages epoch and the subsequent non-linear epochs of cosmic dawn and reionization. Our analysis shows that the baryonic nature of hydrogen cannot be ignored during the dark ages, and that non-linear effects in density-field evolution must be accounted for after stars have formed. Furthermore, we discuss how the 21-cm signal is modified at lower redshifts, where ground-based 21-cm interferometers are mostly sensitive, due to the choice of working with either the "linear" or "non-linear" matter over-density (that is, the over-density as computed from linear perturbation theory, and non-linear perturbation theory, respectively) in the extended Press-Schechter formalism. Our code is publicly available at this https URL.

Using early data from the Dark Energy Spectroscopic Instrument (DESI) survey, we search for AGN signatures in 410,757 line-emitting galaxies. By employing the BPT emission-line ratio diagnostic diagram, we identify AGN in 75,928/296,261 ($\approx$25.6%) high-mass ($\log (M_{\star}/\rm M_{\odot}) >$ 9.5) and 2,444/114,496 ($\approx$2.1%) dwarf ($\log (M_{\star}/\rm M_{\odot}) \leq$ 9.5) galaxies. Of these AGN candidates, 4,181 sources exhibit a broad H$\alpha$ component, allowing us to estimate their BH masses via virial techniques. This study more than triples the census of dwarf AGN as well as that of intermediate-mass black hole (IMBH; $M_{\rm BH} \le 10^6~\rm M_{\odot}$) candidates, spanning a broad discovery space in stellar mass (7 $< \log (M_{\star}/\rm M_{\odot}) <$ 12) and redshift (0.001 $< \rm z <$ 0.45). The observed AGN fraction in dwarf galaxies ($\approx$2.1%) is nearly four times higher than prior estimates, primarily due to DESI's smaller fiber size, which enables the detection of lower luminosity dwarf AGN candidates. We also extend the $M_{\rm BH}$ - $M_{\star}$ scaling relation down to $\log (M_{\star}/\rm M_{\odot}) \approx$ 8.5 and $\log (M_{\rm BH}/M_{\odot}) \approx$ 4.4, with our results aligning well with previous low-redshift studies. The large statistical sample of dwarf AGN candidates from current and future DESI releases will be invaluable for enhancing our understanding of galaxy evolution at the low-mass end of the galaxy mass function.

X-ray observations of galaxy clusters are routinely used to derive radial distributions of ICM thermdynamical properties such as density and temperature. However, observations allow us to access quantities projected on the celestial sphere only, so that an assumption on the 3D distribution of the ICM is necessary. Usually, spherical geometry is assumed. The aim of this paper is to determine the bias due to this approximation on the reconstruction of ICM density radial profile of a clusters sample and on the intrinsic scatter of the density profiles distribution, when clusters substructures are not masked. We used 98 simulated clusters for which we know the 3D ICM distribution drawn from The Three Hundred project. For each cluster we simulated 40 different observations by projecting the cluster along 40 different lines of sight. We extracted the ICM density profile from each observation assuming the ICM to be spherical distributed. For each line of sight we then considered the mean density profile over the sample and compared it with the 3D density profile given by the simulations. The spherical bias on the density profile is derived by considering the ratio between the observed and the input quantities. We also study the bias on the intrinsic scatter of the density profile distribution performing the same procedure. We find a bias on the density profile, $b_n$, smaller than $10\%$ for $R\lesssim R_{500}$ while it increases up to $\sim 50\%$ for larger radii. The bias on the intrinsic scatter profile, $b_s$, reaches a value of $\approx 100\%$ for $R\approx R_{500}$. The bias on both the analysed quantities strongly depends on the morphology of the objects: for clusters that do not show large scale substructures, both $b_n$ and $b_s$ are reduced by a factor 2, conversely for systems that do show large scale substructures both $b_n$ and $b_s$ increase significantly. [abridged]

The discrepancy between the Hubble constant $H_0$ values derived from early-time and late-time measurements, reaching up to $4\sigma$, represents the most serious challenge in modern cosmology and astrophysics. In this work, we investigate if a similar tension exists between only late time measurements at different redshifts. We use the latest public datasets including Cosmic Chronometers, Megamasers, SNe Ia and DESI-BAO, that span from redshift $z \sim 0$ up to $z\sim 2.3$. By dividing the data into redshift bins, we derive $H_0$ values from each bin separately. Our analysis reveals a phenomenological dynamic evolution in $H_0$ across different redshift ranges, with a significance from $1.5\sigma$ and $2.3\sigma$, depending on the parameterization. Consistency of the model demands observational constancy of $H_0$ since it is an integration constant within the Friedmann-Lemaître-Robertson-Walker (FLRW) metric. Thus, these findings suggest that the observed Hubble tension might not only exist between early and late-time measurements but also among late-time data themselves, providing new insights into the nature of the Hubble tension.

The reported discovery of a cold ($\sim$10$^4~\text{K}$) disc-like structure around the super-massive black hole at the centre of the Milk Way, Sagittarius A* (Sgr A*), has challenged our understanding of the gas dynamics and thermodynamic state of the plasma in its immediate vicinity. State-of-the-art simulations do not agree on whether or not such a disc can indeed be a product of the multiple stellar wind interactions of the mass-losing stars in the region. This study aims to constrain the conditions for the formation of a cold disc as a natural outcome of the system of the mass-losing stars orbiting around Sgr A*, to investigate if the disc is a transient or long-lasting structure, and to assess the validity of the model through direct comparisons with observations. We conduct a set of hydrodynamic simulations of the observed Wolf-Rayet (WR) stars feeding Sgr A* using the finite-volume adaptive mesh-refinement code Ramses. We focus, for the first time, on the impact of the chemical composition of the plasma emanating from the WR stars. The simulations show that the chemical composition of the plasma affects the radiative cooling enough to impact the properties of the medium such as density and temperature and, as a consequence, the rate at which the material inflows onto Sgr A*. We demonstrated that the formation of a cold disc from the stellar winds is possible for certain chemical compositions that are consistent with the current observational constraints. However, even in such a case, it is not possible to reproduce the reported properties of the observed disc-like structure, namely its inclination and hydrogen recombination line fluxes. We conclude that the stellar winds on their own cannot form the cold disc around Sgr A* inferred from the observations. Either relevant ingredients are still missing in the model, or the interpretation of the observed data needs to be revised.

High-velocity outflows are ubiquitous in star-forming galaxies at cosmic noon, but are not as common in passive galaxies at the same epoch. Using optical spectra of galaxies selected from the UKIDSS Ultra Deep Survey (UDS) at z > 1, we perform a stacking analysis to investigate the transition in outflow properties along a quenching time sequence. To do this, we use MgII (2800 A) absorption profiles to investigate outflow properties as a function of time since the last major burst of star formation (tburst). We find evidence for high-velocity outflows in the star-forming progenitor population (vout ~ 1400 $\pm$ 210 km/s), for recently quenched galaxies with tburst < 0.6 Gyr (vout ~ 990 $\pm$ 250 km/s), and for older quenched galaxies with 0.6 < tburst < 1 Gyr (vout ~ 1400 $\pm$ 220 km/s). The oldest galaxies (tburst > 1 Gyr) show no evidence for significant outflows. Our samples show no signs of AGN in optical observations, suggesting that any AGN in these galaxies have very short duty cycles, and were 'off' when observed. The presence of significant outflows in the older quenched galaxies (tburst > 0.6 Gyr) is difficult to explain with starburst activity, however, and may indicate energy input from episodic AGN activity as the starburst fades.

Observations of Faraday rotation and synchrotron emission in galaxy clusters imply large-scale magnetic fields with $\mu\mathrm{G}$ strengths possibly extending back to $z=4$. Non-radiative cosmological simulations of galaxy clusters show a comparably slow magnetic field growth that only saturates at late times. We include galaxy formation physics and find a significantly accelerated magnetic field growth. We identify three crucial stages in the magnetic field evolution. 1) At high redshift, the central dominant galaxy serves as the prime agent that magnetizes not only its immediate vicinity but also most of the forming protocluster through a combination of a small-scale dynamo induced by gravitationally driven, compressive turbulence and stellar and active galactic nuclei feedback that distribute the magnetic field via outflows. 2) This process continues as other galaxies merge into the forming cluster in subsequent epochs, thereby transporting their previously amplified magnetic field to the intracluster medium (ICM) through ram pressure stripping and galactic winds. 3) At lower redshift, gas accretion and frequent cluster mergers trigger additional small-scale dynamo processes, thereby preventing the decay of the magnetic field and fostering the increase of the magnetic coherence scale. We show that the magnetic field observed today in the weakly collisional ICM is consistently amplified on collisional scales. Initially, this occurs in the collisional interstellar medium during protocluster assembly, and later in the ICM on the magnetic coherence scale, which always exceeds the particle mean free path, supporting the use of magneto-hydrodynamics for studying the cluster dynamo. We generate synthetic Faraday rotation measure observations of protoclusters, highlighting the potential for studying magnetic field growth during the onset of cluster formation at cosmic dawn.

We present the Baryon Pasted (BP) X-ray and thermal Sunyaev-Zel'dovich (tSZ) maps derived from the half-sky Uchuu Lightcone simulation. These BP-Uchuu maps are constructed using more than $75$ million dark matter halos with masses $M_{500c} \geq 10^{13} M_\odot$ within the redshift range $0 \leq z \leq 2$. A distinctive feature of our BP-Uchuu Lightcone maps is their capability to assess the influence of both extrinsic and intrinsic scatter caused by triaxial gaseous halos and internal gas characteristics, respectively, at the map level. We show that triaxial gas drives substantial scatter in X-ray luminosities of clusters and groups, accounting for nearly half of the total scatter in core-excised measurements. Additionally, scatter in the thermal pressure and gas density profiles of halos enhances the X-ray and SZ power spectra, leading to biases in cosmological parameter estimates. These findings are statistically robust due to the extensive sky coverage and large halo sample in the BP-Uchuu maps.

The Pierre Auger Observatory has revealed a significant challenge in air shower physics: a discrepancy between the simulated and observed muon content in cosmic-ray interactions, known as the 'Muon Puzzle'. This issue stems from a lack of understanding of high-energy hadronic interactions. Current state-of-the-art hadronic interaction models fall short, underscoring the need for improvements. In this contribution, we explore the integration of the Pythia 8 hadronic interaction model into air shower simulations. While Pythia 8 is primarily used in Large Hadron Collider experiments, recent advancements in its Angantyr module show promise in better describing hadron-nucleus interactions, making it a valuable tool for addressing the Muon Puzzle.

We present observations of the high-mass star-forming region S255IR, which harbors the $\sim$20 M$_\odot$ protostar NIRS3, where a disk-mediated accretion burst was recorded several years ago, with the angular resolution of $\sim$15 mas, which corresponds to $\sim$25 au and is almost an order of magnitude better than in the previous studies of this object. The observations were performed with ALMA at a wavelength of 0.9 mm in continuum and in several molecular lines. In the continuum we detected the central bright source (brightness temperature $\sim$850 K) elongated along the jet direction and two pairs of bright knots in the jet lobes. These pairs of knots imply a double ejection from NIRS3 with the time interval of $\sim$1.5 years. The orientation of the jet differs by $\sim$20$^\circ$ from that on larger scales, as mentioned also in some other recent works. The 0.9 mm continuum emission of the central source represents a mixture of the dust thermal emission and free-free emission of the ionized gas. Properties of the free-free emission are typical for hypercompact H II regions. In the continuum emission of the knots in the jet the free-free component apparently dominates. In the molecular lines a sub-Keplerian disk around NIRS3 about 400 au in diameter is observed. The absorption features in the molecular lines towards the central bright source may indicate an infall. The molecular line emission appears very inhomogeneous at small scales, which may indicate a small-scale clumpiness in the disk.

We present three separate void catalogs created using a volume-limited sample of the DESI Year 1 Bright Galaxy Survey. We use the algorithms VoidFinder and V2 to construct void catalogs out to a redshift of z=0.24. We obtain 1,461 interior voids with VoidFinder, 420 with V2 using REVOLVER pruning, and 295 with V2 using VIDE pruning. Comparing our catalog with an overlapping SDSS void catalog, we find generally consistent void properties but significant differences in the void volume overlap, which we attribute to differences in the galaxy selection and survey masks. These catalogs are suitable for studying the variation in galaxy properties with cosmic environment and for cosmological studies.

We present statistical analysis of video meteor observations for the Perseid and Geminid showers taken with two camera systems operating in Hungary from the end of 2019 through 2023. Zenithal hourly rates (ZHR) and meteor fluxes, determined by MetRec-based analog video cameras HUKON, HUPIS and HUHOD, are inferred and compared with detections of slow fireballs measured at the same sites by a system consisting of automated DSLR cameras (the KoMON system).

Time-of-arrival (TOA) measurements of pulses from pulsars are conventionally made by a template matching algorithm that compares a profile constructed by averaging a finite number of pulses to a long-term average pulse shape. However, the shapes of pulses can and do vary, leading to errors in TOA estimation. All pulsars show stochastic variations in shape, amplitude, and phase between successive pulses that only partially average out in averages of finitely many pulses. This jitter phenomenon will only become more problematic for timing precision as more sensitive telescopes are built. We describe techniques for characterizing jitter (and other shape variations) and demonstrate them with data from the Vela pulsar, PSR B0833$-$45. These include partial sum analyses; auto-and cross correlations between templates and profiles and between multifrequency arrival times; and principal component analysis. We then quantify how pulse shape changes affect TOA estimates using both analytical and simulation methods on pulse shapes of varying complexity (multiple components). These methods can provide the means for improving arrival time precision for many applications, including gravitational wave astronomy using pulsar timing arrays.

In this work, we examine seven systems discovered by TESS, to see whether there is any room in those systems for an additional planet (or several) to lurk unseen between the two planets already confirmed therein. In five of those systems (namely HD 15337; HD 21749; HD 63433; HD 73583 and LTT 3780) we find that there is ample room for an undiscovered planet to move between those that have already been discovered. In other words, as they currently stand, those systems are not tightly packed. In stark contrast, the perturbative influence of the two known TOI-1670 planets is such that additional planets in between are ruled out. The final system, TOI 421, is more challenging. In the vast majority of cases, adding an Earth-mass planet to that system between the orbits of the known planets caused catastrophic instability. Just ~1.1% of our simulations of the modified system proved dynamically stable on a timescale of one million years. As a result, it seems that there is very little room between the two known planets in the TOI 421 system for an addition unseen world to exist, but the existence of such a planet can not be definitely ruled out on dynamical grounds alone.

ALMA surveys have suggested that protoplanetary disks are not massive enough to form the known exoplanet population, under the assumption that the millimeter continuum emission is optically thin. In this work, we investigate how the mass determination is influenced when the porosity of dust grains is considered in radiative transfer models. The results show that disks with porous dust opacities yield similar dust temperature, but systematically lower millimeter fluxes compared to disks incorporating compact dust grains. Moreover, we recalibrate the relation between dust temperature and stellar luminosity for a wide range of stellar parameters, and calculate the dust masses of a large sample of disks using the traditionally analytic approach. The median dust mass from our calculation is about 6 times higher than the literature result, and this is mostly driven by the different opacities of porous and compact grains. A comparison of the cumulative distribution function between disk dust masses and exoplanet masses show that the median exoplanet mass is about 2 times lower than the median dust mass, if grains are porous, and there are no exoplanetary systems with masses higher than the most massive disks. Our analysis suggests that adopting porous dust opacities may alleviate the mass budget problem for planet formation. As an example illustrating the combined effects of optical depth and porous dust opacities on the mass estimation, we conduct new IRAM/NIKA-2 observations toward the IRAS 04370+2559 disk and perform a detailed radiative transfer modeling of the spectral energy distribution. The best-fit dust mass is roughly 100 times higher than the value from the traditionally analytic calculation. Future spatially resolved observations at various wavelengths are required to better constrain the dust mass.

During the last decade, studies about highly attenuated and massive red star-forming galaxies (RedSFGs) at $z \sim 4$ have suggested that they could constitute a crucial population for unraveling the mechanisms driving the transition from vigorous star formation to quiescence at high redshifts. Since such a transition seems to be linked to a morphological transformation, studying the morphological properties of these RedSFGs is essential to our understanding of galaxy evolution. To this end, we are using JWST/NIRCam images from the CEERS survey to assemble a mass-complete sample of 188 massive galaxies at $z=3-4$, for which we perform resolved-SED fit. After classifying galaxies into typical blue SFGs (BlueSFGs), RedSFGs and quiescent galaxies (QGs), we compare the morphologies of each population in terms of stellar mass density, SFR density, sSFR, dust-attenuation and mass-weighted age. We find that RedSFGs and QGs present similar stellar surface density profiles and that RedSFGs manifest a dust attenuation concentration significantly higher than that of BlueSFGs at all masses. This indicates that to become quiescent, a BlueSFG must transit through a major compaction phase once it has become sufficiently massive. At the same time, we find RedSFGs and QGs to account for more than $50\%$ of galaxies with ${\rm log}(M_\ast/M_\odot)> 10.4$ at this redshift. This transition mass corresponds to the "critical mass" delineating the bimodality between BlueSFGs and QGs in the local Universe. We then conclude that there is a bimodality between extended BlueSFGs and compact, highly attenuated RedSFGs that have undergone a major gas compaction phase enabling the latter to build a massive bulb in situ. There is evidence that this early-stage separation is at the origin of the local bimodality between BlueSFGs and QGs, which we refer to as a "primeval bimodality".

Quasi-periodic eruptions (QPEs) are recurring bursts of soft X-rays from the nuclei of galaxies. Their physical origin is currently a subject of debate, with models typically invoking an orbiter around a massive black hole or disk instabilities. Here we present and analyze the temporal and spectral evolution of the QPE source eRO-QPE2 over 3.5 years. We find that eRO-QPE2 1) is remarkably stable over the entire 3.5-year temporal baseline in its eruption peak luminosity, eruption temperature, quiescent temperature, and quiescent luminosity, 2) has a stable mean eruption recurrence time of 2.35 hours, with marginal ($\sim$2$\sigma$) evidence for a $0.1$ hour reduction over the 3.5 yr period, and 3) has a long-short variation in its recurrence time in August 2020, but this pattern is absent from all subsequent observations. The stability of its peak eruption luminosity and that of the quiescent state are notably dissimilar from three previously tracked QPEs (GSN069, eRO-QPE1, eRO-QPE3), which show declines in eruption and quiescent flux over comparable temporal baselines. This stability is even more pronounced in eRO-QPE2 due to its 2.4 hour average recurrence time compared to GSN-069's 9 hour, eRO-QPE1's 16 hour, and eRO-QPE3's 20 hour recurrence times, i.e., this system has undergone 4-8 times more cycles than these other systems over the 3.5 years of observations. We discuss the implications of these observations within the context of some proposed extreme mass ratio inspiral (EMRI) models.

We present steady-state solutions for a one-dimensional, magnetically-driven accretion disk wind model based on magnetohydrodynamic equations. We assume a geometrically thin, gas-pressure-dominated accretion disk, incorporating both magnetic braking and turbulent viscosity introduced by an extended alpha-viscosity prescription. Additionally, the vertical stress parameter is assumed to scale with the disk aspect ratio. We confirm that the derived solutions result in standard disk solutions when the wind is absent. We find that the mass accretion rate decreases as the disk mass falls inward, while the mass loss rate increases with radius. The disk spectrum emitted from the magnetically-driven disk wind can be observed without interference from the wind medium because the wind is significantly optically thin. The spectral luminosity is proportional to $\nu^{1/3}$ in the intermediate, multicolor-blackbody wavebands, in the absence of wind, as predicted by standard disk theory. However, in the presence of wind, it follows a different power-law dependence on frequency over the same range. A deviation from the spectral slope of $1/3$, particularly a negative spectral slope, is a clear indicator of the presence of a magnetically driven wind. We also discuss an observational strategy to test our model with multi-wavelength observations.

The large-scale imaging survey will produce massive photometric data in multi-bands for billions of galaxies. Defining strategies to quickly and efficiently extract useful physical information from this data is mandatory. Among the stellar population parameters for galaxies, their stellar masses and star formation rates (SFRs) are the most fundamental. We develop a novel tool, \textit{Multi-Layer Perceptron for Predicting Galaxy Parameters} (MLP-GaP), that uses a machine-learning (ML) algorithm to accurately and efficiently derive the stellar masses and SFRs from multi-band catalogs. We first adopt a mock dataset generated by the \textit{Code Investigating GALaxy Emission} (CIGALE) for training and testing datasets. Subsequently, we used a multi-layer perceptron model to build MLP-GaP and effectively trained it with the training dataset. The results of the test performed on the mock dataset show that MLP-GaP can accurately predict the reference values. Besides MLP-GaP has a significantly faster processing speed than CIGALE. To demonstrate the science-readiness of the MLP-GaP, we also apply it to a real data sample and compare the stellar masses and SFRs with CIGALE. Overall, the predicted values of MLP-GaP show a very good consistency with the estimated values derived from SED fitting. Therefore, the capability of MLP-GaP to rapidly and accurately predict stellar masses and SFRs makes it particularly well-suited for analyzing huge amounts of galaxies in the era of large sky surveys.

We present the first X-ray polarization measurement of the neutron star low-mass X-ray binary and Z-source, GX 340$+$0, in the normal branch (NB) using a 200 ks observation with the Imaging X-ray Polarimetric Explorer (IXPE). This observation was performed in 2024 August. Along with IXPE, we also conducted simultaneous observations with NICER, AstroSat, Insight-HXMT, ATCA, and GMRT to investigate the broadband spectral and timing properties in the X-ray and radio wavelengths. During the campaign, the source traced a complete Z-track during the IXPE observation but spent most of the time in the NB. We measure X-ray polarization degree (PD) of $1.22\pm0.25\%$ in the 2-8 keV energy band with a polarization angle (PA) of $38\pm6^\circ$. The PD in the NB is observed to be weaker than in the horizontal branch (HB) but aligned in the same direction. The PD of the source exhibits a marginal increase with energy while the PA shows no energy dependence. The joint spectro-polarimetric modeling is consistent with the observed X-ray polarization originating from a single spectral component from the blackbody, the Comptonized emission, or reflection feature, while the disk emission does not contribute towards the X-ray polarization. GMRT observations at 1.26 GHz during HB had a tentative detection at 4.5$\pm$0.7 mJy while ATCA observations a day later during the NB detected the source at 0.70$\pm$0.05 mJy and 0.59$\pm$0.05 mJy in the 5.5 & 9 GHz bands, respectively, suggesting an evolving jet structure depending on the Z-track position.

We investigate the effects of the magnetic field and the redshift on the propagation of galactic and extragalactic cosmic rays (CRs) in a modified theory of gravity (MTG) and an alternative theory of gravity (ATG) framework. For this purpose, we consider the $f(R)$ gravity and the $f(Q)$ gravity theories. We utilise these two MTG and ATG to compute the density enhancement factor of CRs as a function of the magnetic field and the redshift. For this work, we take the magnetic field strength from $1-100$ nG, while $0-2.5$ for the redshift. For each of these parameters, we take $100$ bins within their considered range for the computation. The enhancement parameter for the mixed composition of heavy nuclei up to Fe is also taken into account for this work. Further, we compute the $E^3$ magnified diffusive flux for $150$ sources separated by a distance $d_\text{s}$ for the different cosmological models. For the fitting with observational data from the Pierre Auger Observatory (PAO) and Telescope Array (TA), we parameterized some set that consists of the redshift $z$, the separation distances $d_\text{s}$ between the $150$ sources, and the maximum cutoff energy $E_{\text{max}}$. For each case, a residue plot and $\chi^2$ value are also added to check the goodness of fitting. A comparative analysis of considered models has been performed in each of the cases along with the $\Lambda$CDM model. The considered MTG and ATG models produce notable and fascinating outcomes, with the $f(Q)$ model showing the highest CR density enhancement and the lowest reduced chi-squared value when fitted to PAO and TA data of UHECRs flux. This research provides new perspectives on the connections between high-energy physics, astrophysics, and cosmology.

Ultraluminous X-ray sources (ULXs) are non-nuclear point-like objects observed with extremely high X-ray luminosity that exceeds the Eddington limit of a $\rm10\,M_\odot$ black hole. A fraction of ULXs has been confirmed to contain neutron star (NS) accretors due to the discovery of their X-ray pulsations. The donors detected in NS ULXs are usually luminous massive stars because of the observational biases. Recently, the He donor star in NGC 247 ULX-1 has been identified, which is the first evidence of a He donor star in ULXs. In this paper, we employed the stellar evolution code MESA to investigate the formation of ULXs through the NS+He star channel, in which a He star transfers its He-rich material onto the surface of a NS via Roche-lobe overflow. We evolved a large number of NS+He star systems and provided the parameter space for the production of ULXs. We found that the initial NS+He star systems should have $\rm\sim 0.7-2.6 \, M_\odot$ He star and $\rm \sim 0.1-2500\, d$ orbital period for producing ULXs, eventually evolving into intermediate-mass binary pulsars. According to binary population synthesis calculations, we estimated that the Galactic rate of NS ULXs with He donor stars is in the range of $\sim1.6-4.0\times10^{-4}\,{\rm yr}^{-1}$, and that there exist $\sim7-20$ detectable NS ULXs with He donor stars in the Galaxy.

We present results of a comprehensive analysis of the polarization characteristics of GRB 200503A and GRB 201009A observed with the Cadmium Zinc Telluride Imager (CZTI) on board AstroSat. Despite these GRBs being reasonably bright, they were missed by several spacecraft and had thus far not been localized well, hindering polarization analysis. We present positions of these bursts obtained from the Inter-Planetary Network (IPN) and the newly developed CZTI localization pipeline. We then undertook polarization analyses using the standard CZTI pipeline. We cannot constrain the polarization properties for GRB 200503A, but find that GRB 201009A has a high degree of polarization.

Sunspot-area measurements using digital images captured by two telescopes at the Mitaka campus of the National Astronomical Observatory of Japan are conducted using automated sunspot detection. A comparison between sunspot areas derived from Mitaka and those from the reference data by Mandal et al. ({\it Astron. Astrophys.} {\bf 640,} A78, 2020), who compiled a cross-calibrated daily sunspot-area catalog, revealed that the correlation coefficients between them are high (0.96--0.97), whereas the areas in the Mitaka data are 70 \%--83 \% of those of Mandal et al. The correlation is limited by the differences in observation times and detection capabilities of spots near the limb, with discrepancies in areas arising from different definitions of spot outlines. Given the high correlation and the ease of calibrating area discrepancies with a correction factor, automated sunspot detection appears promising for future sunspot-area measurements. Furthermore, we addressed the measurements of brightness deficit caused by sunspots.

We study the stellar, neutral gas content within halos over a halo mass range $10^{10} \text{ to } 10^{15.5} \text{M}_\odot$ and hot X-ray gas content over a halo mass range $10^{12.8} \text{ to } 10^{15.5} \text{M}_\odot$ in the local universe. We combine various empirical datasets of stellar, \HI\ and X-ray observations of galaxies, groups and clusters to establish fundamental baryonic mass vs halo mass scaling relations. These scaling relations are combined with halo mass function to obtain the baryon densities of stars, neutral gas and hot gas ($T>10^6 \text{K}$), as a function of halo mass. We calculate the contributions of the individual baryonic components to the cosmic baryon fraction. Cosmic stellar mass density ($\Omega_\text{star}=2.09^{+0.21}_{-0.18} \times 10^{-3}$), cosmic HI mass density ($\Omega_\text{HI}=0.49^{+0.25}_{-0.12} \times 10^{-3}$) and cosmic neutral gas mass density ($\Omega_\text{neutral gas}=0.71^{+0.39}_{-0.18} \times 10^{-3}$) estimates are consistent with previous more direct method measurements of these values, thereby establishing the veracity of our method. We also give an estimate of the cosmic hot plasma density ($\Omega_\text{hot gas}=2.58^{+2.1}_{-0.66} \times 10^{-3}$).

The identification of large numbers of localised transient EUV brightenings, with small spatial scales, in the quiet-Sun corona has been one of the key early results from Solar Orbiter. However, much is still unknown about these events. Here, we aim to better understand EUV brightenings by investigating their spatial distributions, specifically whether they occur co-spatial with specific line-of-sight magnetic field topologies in the photospheric network. EUV brightenings are detected using an automated algorithm applied to a high-cadence (3 s) dataset sampled over ~30 min on 8 March 2022 by the Extreme Ultraviolet Imager's 17.4 nm EUV High Resolution Imager. Data from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly are used to provide context about the line-of-sight magnetic field and for alignment purposes. We found a total of 5064 EUV brightenings within this dataset that are directly comparable to events reported previously in the literature. These events occurred within around 0.015-0.020 % of pixels for any given frame. We compared eight different thresholds to split the EUV brightenings into four different categories related to the line-of-sight magnetic field. Using our preferred threshold, we found that 627 EUV brightenings (12.4 %) occurred co-spatial with Strong Bipolar configurations and 967 EUV brightenings (19.1 %) occurred in Weak Field regions. Fewer than 10 % of EUV brightenings occurred co-spatial with Unipolar line-of-sight magnetic field no matter what threshold was used. Of the 627 Strong Bipolar EUV Brightenings, 54 were found to occur co-spatial with cancellation whilst 57 occurred co-spatial with emergence. EUV brightenings preferentially occur co-spatial with the strong line-of-sight magnetic field in the photospheric network. They do not, though, predominantly occur co-spatial with (cancelling) bi-poles.

The Faint Particle Trigger (FPT) was developed for the IceCube Neutrino Observatory to enhance the detection efficiency for faint signatures, produced by free Fractionally Charged Particles (FCP) predicted in several Standard Model (SM) extensions. A previous IceCube analysis has shown a reduced trigger efficiency in detecting FCP with a charge of e/3 due to the $\text{z}^2$ dependence of photon production processes. The FPT addresses this shortcoming by incorporating a so far unused hit type, so called SLC hits in the trigger decision. These are single isolated hits that are not used for triggering high energy signatures in IceCube. The FPT employs a sliding time window to analyze hits, utilizing four cuts to remove noise and bright background contributions. The noise contribution is effectively decreased to a few Hz by velocity and directional consistency of hit pairs. Furthermore a part of the dominating atmospheric muon rate is reduced, by requiring a minimum fraction of SLC hits in the trigger window. The FPT significantly improves the trigger efficiency by a factor of 1.55, compared to standard triggers, while increasing the event rate in IceCube by a factor 1.004. The trigger algorithm was tested and successfully deployed at South Pole in November 2023.

The objective of the coronagraphic IFU of RISTRETTO is to enable High Dispersion Coronagraphy of planets at a distance of 2$\lambda$/D from their star, without compromising on transmission. The new idea of a PIAA Nuller (PIAAN) allows contrast down to 10$^{-5}$ over large bandwidth $\ge$ 25%, with high transmission $\ge$ 70% at the distance of 2$\lambda$/D. While RISTRETTO will be installed on a VLT, this development is of tremendous importance for fully exploiting future ELTs XAO. We will discuss our PIAAN prototyping activities. This covers 1) the characterisation of our 2nd set of IFU bundles, with 3D-printed MLAs; 2) the characterisation of our first PIAA optics; 3) the integration of a high contrast bench, planned for prototyping of Front-End control strategies; 4) the characterisation of the PIAAN system on the bench.

The formation mechanism of interstellar formamide (NH$_2$CHO), a key prebiotic precursor, is currently a matter of hot debate within the astrochemistry community, with both gas-phase and grain-surface chemical pathways having been proposed as its dominant formation route. The aim of the present study is to place firm observational constraints on the formation pathways leading to formamide thanks to new interferometric observations of the molecular outflow driven by the protostellar binary L1157. We employed the IRAM NOEMA interferometer to map the entire southern outflow of L1157, which contains three main shocked regions with increasing post-shock age: B0, B1, and B2. This allowed us to measure how the abundance of formamide, that of acetaldehyde (CH$_3$CHO), and the ratio of the two, vary with time in this region. In order to gain a greater understanding of the most likely formation routes of formamide, we ran a grid of astrochemical models and compared these to our observations. A comparison between observations and astrochemical modelling indicates that there are two possible scenarios: one in which the amount of formamide observed can be explained by gas-phase-only chemistry, and more specifically via the reaction H$_2$CO + NH$_2$ $\rightarrow$ NH$_2$CHO + H$_2$, and another in which part of the observed formamide originates from surface chemistry and part from gas-phase chemistry. Surface chemistry alone cannot account for the abundance of formamide that we measure. While grain-surface chemistry cannot be ruled out, the present study brings definitive proof that gas-phase chemistry does work in L1157-B and acts efficiently in the production of this molecular species.

The double neutron star PSR J1846-0513 is discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. The pulsar is revealed to be harbored in an eccentric orbit with $e=0.208$ and orbital period of 0.613 days. The total mass of the system is constrained to be $2.6287(35)\rm{M}_{\odot}$, with a mass upper limit of $1.3455{\rm~M}_{\odot}$ for the pulsar and a mass lower limit of $1.2845{\rm~M}_{\odot}$ for the companion star. To reproduce its evolution history, we perform a 1D model for the formation of PSR J1846-0513 whose progenitor is assumed to be neutron star - helium (He) star system via MESA code. Since the large eccentricity is widely believed to originate from an asymmetric supernova explosion, we also investigate the dynamical effects of the supernova explosion. Our simulated results show that the progenitor of PSR J1846-0513 could be a binary system consisting of a He star of $3.3-4.0{\rm~M}_\odot$ and a neutron star in a circular orbit with an initial period of $\sim0.5$ days.

The stellar initial mass function (IMF) is a key parameter to understand the star formation process and the integrated properties of stellar populations in remote galaxies. We present a spectroscopic study of young massive clusters (YMCs) in the starburst galaxies NGC 4038/39. The integrated spectra of seven YMCs obtained with GMOS-S attached to the 8.2-m Gemini South telescope reveal the spectral features associated with stellar ages and the underlying IMFs. We constrain the ages of the YMCs using the absorption lines and strong emission bands from Wolf-Rayet stars. The internal reddening is also estimated from the strength of the Na I D absorption lines. Based on these constraints, the observed spectra are matched with the synthetic spectra generated from a simple stellar population model. Several parameters of the clusters including age, reddening, cluster mass, and the underlying IMF are derived from the spectral matching. The ages of the YMCs range from 2.5 to 6.5 Myr, and these clusters contain stellar masses ranging from 1.6 X 10^5 M_sun to 7.9 X 10^7 M_sun. The underlying IMFs appear to differ from the universal form of the Salpeter/Kroupa IMF. Interestingly, massive clusters tend to have the bottom-heavy IMFs, although the masses of some clusters are overestimated due to the crowding effect. Based on this, our results suggest that the universal form of the IMF is not always valid when analyzing integrated light from unresolved stellar systems. However, further study with a larger sample size is required to reach a definite conclusion.

The nature of the gravitational wave background (GWB) is a key question in modern astrophysics and cosmology, with significant implications for understanding of the structure and evolution of the Universe. We demonstrate how cross-correlating large-scale structure (LSS) tracers with the GWB spatial anisotropies can extract a clear astrophysical imprint from the GWB signal. Focusing on the unresolved population of supermassive black hole binaries (SMBHBs) as the primary source for the GWB at nanohertz frequencies, we construct full-sky maps of galaxy distributions and characteristic strain of the GWB to explore the relationship between GWB anisotropies and the LSS. We find that at current pulsar timing array (PTA) sensitivities, very few loud SMBHBs act as Poisson-like noise. This results in anisotropies dominated by a small number of sources, making GWB maps where SMBHBs trace the LSS indistinguishable from a GWBs from a uniform distribution of SMBHBs. In contrast, we find that the bulk of the unresolved SMBHBs produce anisotropies which mirror the spatial distribution of galaxies, and thus trace the LSS. Importantly, we show that cross-correlations are required to retrieve a clear LSS imprint in the GWB. Specifically, we find this LSS signature can me measured at a $3\sigma$ level in near-future PTA experiments that probe angular scales of $\ell_{\text{max}} \geq 42$, and $5\sigma$ for $\ell_{\text{max}} \geq 72$. Our approach opens new avenues to employ the GWB as an LSS tracer, providing unique insights into SMBHB population models and the nature of the GWB itself. Our results motivate further exploration of potential synergies between next-generation PTA experiments and cosmological tracers of the LSS.

We present a freeze-out approach to the formation of heavy elements in expanding nuclear matter. Applying concepts used in the description of heavy-ion collisions or ternary fission, we determine the abundances of heavy elements taking into account in-medium effects such as Pauli blocking and the Mott effect, which describes the dissolution of nuclei at high densities of nuclear matter. With this approach, we search for a universal primordial distribution in an equilibrium state from which the gross structure of the solar abundances of heavy elements freezes out via radioactive decay of the excited states. The universal primordial state is characterized by the Lagrangian parameters of temperature and chemical potentials of neutrons and protons. We show that such a state exists and determine a temperature of 5.266 MeV, a neutron chemical potential of 940.317 MeV and a proton chemical potential of 845.069 MeV, at a baryon number density of 0.013 fm$^{-3}$ and a proton fraction of 0.13. Heavy neutron-rich nuclei such as the hypothesized double-magic nucleus $^{358}$Sn appear in the primordial distribution and contribute to the observed abundances after fission. We discuss astrophysical scenarios for the realization of this universal primordial distribution for heavy element nucleosynthesis, including supernova explosions, neutron star mergers and the inhomogeneous Big Bang. The latter scenario may be of interest in the light of early massive objects observed with the James Webb Space Telescope and opens new perspectives to explain universality of the observed r-process patterns and the lack of observations of population III stars.

In the context of Chameleon gravity, we present a semi-analytical solution of the chameleon field profile in accurately modelled galaxy cluster's mass components, namely: the stellar mass of the Brightest Cluster Galaxy (BCG), the baryonic mass in galaxies (other than the BCG), the mass of the Intra-Cluster Medium (ICM) and the diffuse cold dark matter (CDM). The obtained semi-analytic profile is validated against the numerical solution of the chameleon field equation and implemented in the \textsc{MG-MAMPOSSt} code for kinematic analyses of galaxy clusters in modified gravity scenarios. By means of mock halos, simulated both in GR and in modified gravity, we show that the combination of velocities and positions of cluster member galaxies, along with data of the stellar velocity dispersion profile of the BCG, can impose constraints on the parameter space of the Chameleon model; for a cluster generated in GR, these constraints are at the same level as a joint lensing+kinematics analysis of a cluster modelled with a single mass profile, without the BCG data.

The sulfur content in dense molecular regions of the interstellar medium is highly depleted in comparison to diffuse clouds. The reason of this phenomenon is unclear, thus it is necessary to carry out observational studies of sulfur-bearing species towards dense regions, mainly at early evolutive stages to uncover the early sulfur chemistry. Using data from the Atacama Large Millimeter Array (ALMA) data archive, we investigated a sample of 37 dense cores embedded in the most massive infrared-quiet molecular clumps from the ATLASGAL survey. Lines of 34SO, SO2, NS, SO, SO+, and H2CS were analyzed and column densities of each molecular species were obtained. From the continuum emission, and two CH3OH lines, the 37 cores were characterized in density and temperature, and the corresponding H2 column densities were derived. The abundances of such sulfur-bearing species were derived and studied. We find that the abundances of the analyzed species increase with the growth of the gas temperature, suggesting that the chemistry involved in the formation of each of the analyzed molecule may have a similar dependence with Tk in the range 20 to 100 K. We find that the comparisons among abundances are, in general, highly correlated. Given that such correlation decreases in more evolved sources, we suggest that the sulfur-bearing species here analyzed should have a similar chemical origin. From the measured line widths we point out that molecules with oxygen content (34SO, SO2, SO, and SO+) may be associated with warmer and more turbulent gas than the other ones. H2CS and NS are associated with more quiescent gas, probably in the external envelopes of the cores. This work gives quantitative information about abundances that could be useful in chemical models pointing to explain the sulfur chemistry in the interstellar medium.

In our former paper I, we showed on the Sun that different active regions possess unique intensity profiles on the Ca II H & K lines. We now extend the analysis by showing how those properties can be used on real stellar observations, delivering more powerful activity proxies for radial velocity correction. More information can be extracted on rotational timescale from the Ca II H & K lines than the classical indicators: S-index and log(R'HK). For high-resolution HARPS observations of alpha Cen B, we apply a principal and independent component analysis on the Ca II H & K spectra time-series to disentangle the different sources that contribute to the disk-integrated line profiles. While the first component can be understood as a denoised version of the Mount-Wilson S-index, the second component appears as powerful activity proxies to correct the RVs induced by the inhibition of the convective blueshift in stellar active regions. However, we failed to interpret the extracted component into a physical framework. We conclude that a more complex kernel or bandpass than the classical triangular of the Mount Wilson convention should be used to extract activity proxies. To this regard, we provide the first principal component activity profile obtained across the spectral type sequence between M1V to F9V type stars.

We conducted a multi-wavelength analysis of the blazar Mrk\,501, utilizing observations from \emph{Astro}Sat (SXT, LAXPC), \emph{Swift-UVOT}, and \emph{Fermi-LAT} during the period August 15, 2016 to March 27, 2022. The resulting multi-wavelength light curve revealed relatively low activity of the source across the electromagnetic spectrum. Notably, logparabola and broken power-law models provided a better fit to the joint X-ray spectra from \emph{Astro}Sat-SXT/LAXPC instruments compared to the power-law model. During the low activity state, the source showed the characteristic harder when brighter trend at the X-ray energies. To gain insights into underlying physical processes responsible for the broadband emission, we performed a detailed broadband spectral analysis using the convolved one-zone leptonic model with different forms of particle distributions such as logparabola (LP), broken power-law (BPL), power-law model with maximum energy ($\xi_{max}$), and energy-dependent acceleration (EDA) models. Our analysis revealed similar reduced-$\chi^2$ values for the four particle distributions. The LP and EDA models exhibited the lowest jet powers. The correlation analyses conducted for the LP and BPL models revealed that there is a positive correlation between jet power and bulk Lorentz factor. Specifically, in the LP model, jet power proved independent of $\gamma_{min}$, whereas in the broken power-law model, jet power decreased with an increase in $\gamma_{min}$. The jet power in the LP/EDA particle distribution is nearly 10 percent of the Eddington luminosity of a $10^7$ M$_\odot$ black hole. This result suggests that the jet could potentially be fueled by accretion processes.

The X-ray binary system Cygnus X-3 (4U 2030+40, V1521 Cyg) is luminous but enigmatic owing to the high intervening absorption. High-resolution X-ray spectroscopy uniquely probes the dynamics of the photoionized gas in the system. In this paper we report on an observation of Cyg X-3 with the XRISM/Resolve spectrometer which provides unprecedented spectral resolution and sensitivity in the 2-10 keV band. We detect multiple kinematic and ionization components in absorption and emission, whose superposition leads to complex line profiles, including strong P-Cygni profiles on resonance lines. The prominent Fe XXV He$\alpha$ and Fe XXVI Ly$\alpha$ emission complexes are clearly resolved into their characteristic fine structure transitions. Self-consistent photoionization modeling allows us to disentangle the absorption and emission components and measure the Doppler velocity of these components as a function of binary orbital phase. We find a significantly higher velocity amplitude for the emission lines than for the absorption lines. The absorption lines generally appear blueshifted by ${\sim}-500$-$600$km s$^{-1}$. We show that the wind decomposes naturally into a relatively smooth and large scale component, perhaps originating with the background wind itself, plus a turbulent more dense structure located close to the compact object in its orbit.

The Vela pulsar (J0835-4510) is known to exhibit variations in Faraday rotation and dispersion on multi-decade timescales due to the changing sightline through the surrounding Vela supernova remnant and the Gum Nebula. Until now, variations in Faraday rotation towards Vela have not been studied on timescales less than around a decade. We present the results of a high-cadence observing campaign carried out with the Aperture Array Verification System 2 (AAVS2), a prototype SKA-Low station, which received a significant bandwidth upgrade in 2022. We collected observations of the Vela pulsar and PSR J0630-2834 (a nearby pulsar located outside the Gum Nebula), spanning $\sim 1\,\mathrm{yr}$ and $\sim 0.3\,\mathrm{yr}$ respectively, and searched for linear trends in the rotation measure (RM) as a function of time. We do not detect any significant trends on this timescale ($\sim$months) for either pulsar, but the constraints could be greatly improved with more accurate ionospheric models. For the Vela pulsar, the combination of our data and historical data from the published literature have enabled us to model long-term correlated trends in RM and dispersion measure (DM) over the past two decades. We detect a change in DM of $\sim 0.3\,\mathrm{cm}^{-3}\,\mathrm{pc}$ which corresponds to a change in electron density of $\sim 10^5\,\mathrm{cm}^{-3}$ on a transverse length scale of $\sim$1-2 au. The apparent magnetic field strength in the time-varying region changes from $240^{+30}_{-20}\,\mu\mathrm{G}$ to $-6.2^{+0.7}_{-0.9}\,\mu\mathrm{G}$ over the time span of the data set. As well as providing an important validation of polarimetry, this work highlights the pulsar monitoring capabilities of SKA-Low stations, and the niche science opportunities they offer for high-precision polarimetry and probing the microstructure of the magneto-ionic interstellar medium.

It is well known that silicon photomultipliers (SiPMs) are prone to radiation damage. With the increasing popularity of SiPMs among new spaceborne missions, especially on CubeSats, it is of paramount importance to characterize their performance in space environment. In this work, we report the in-orbit ageing of SiPM arrays, so-called multi-pixel photon counters (MPPCs), using measurements acquired by the GRBAlpha and VZLUSAT-2 CubeSats at low Earth orbit (LEO) spanning over three years, which in duration is unique. GRBAlpha is a 1U CubeSat launched on March 22, 2021, to a 550 km altitude sun-synchronous polar orbit (SSO) carrying on board a gamma-ray detector based on CsI(Tl) scintillator readout by eight MPPCs and regularly detecting gamma-ray transients such as gamma-ray bursts and solar flares in the energy range of ~30-900 keV. VZLUSAT-2 is a 3U CubeSat launched on January 13, 2022 also to a 550 km altitude SSO carrying on board, among other payloads, two gamma-ray detectors similar to the one on GRBAlpha. We have flight-proven the Hamamatsu MPPCs S13360-3050 PE and demonstrated that MPPCs, shielded by 2.5 mm of PbSb alloy, can be used in an LEO environment on a scientific mission lasting beyond three years. This manifests the potential of MPPCs being employed in future satellites.

In June 2022, the Gaia mission released a catalog of astrometric orbital solutions for 168,065 binary systems, by far the largest such catalog to date. Unlike previous binary stars catalogs, which were heterogeneous collections of orbits from different surveys and instruments, these orbits were derived using Gaia data alone. Despite this homogeneity, the selection function is difficult to characterize because of choices made in the construction of the catalog. Understanding the catalog's selection function is required to model and interpret its contents. We use a combination of analytic and empirical prescriptions to construct a function that computes the probability that a binary with a given set of properties would have been published in the Gaia Data Release 3 astrometric orbit catalog. We also construct a binary population synthesis model based on Moe & Di Stefano (2017) to validate our characterization of the selection function, finding good agreement with the actual Gaia NSS catalog, with the exception of the orbital eccentricity distribution. The NSS catalog suggests high-eccentricity orbits are relatively uncommon at intermediate periods $100 \lesssim P_{orb} \lesssim 1000$ days. As an example application of the selection function, we estimate the Gaia DR3 detection probabilities of the star + BH binaries Gaia BH1, BH2, and BH3. We also estimate the population of Sun-like star + BH binaries in the Galaxy to be $\sim 5000$ for $100 < P_{orb} < 400$ day, $\lesssim 2,000$ for $400 < P_{orb} < 1000$ day, and $ \lesssim 20,000$ for $1000 < P_{orb} < 2000$ days.

We investigate the nature of star formation in gas-rich galaxies at $z > 7$ forming in a markedly overdense region, in the whereabouts of a massive virialized halo already exceeding $10^{12}$ M$_{\odot}$. We find that not only the primary galaxy, but also the lower-mass companion galaxies rapidly develop massive self-gravitating compact gas disks, less than 500~pc in size, which undergo fragmentation by gravitational instability into very massive bound clumps. Star formation proceeds fast in the clumps, which quickly turn into compact star clusters with masses in the range $10^5$-$10^8$ M$_{\odot}$ and typical half-mass radii of a few pc, reaching characteristic densities above $10^5$ M$_{\odot}$ pc$^{-2}$. The properties of the clusters in the lowest-mass galaxy bear a striking resemblance to those recently discovered by the James Webb Space Telescope (JWST) in the lensed Cosmic Gems arc system at $z = 10.2$. We argue that, due to their extremely high stellar densities, intermediate-mass black holes (IMBHs) would form rapidly inside the clusters, which would then swiftly sink and merge on their way to the galactic nucleus, easily growing a $10^7$~M$_{\odot}$ supermassive black hole (SMBH). Due to the high fractional mass contribution of clusters to the stellar mass of the galaxies, in the range $20$-$40\%$, the central SMBH would comprise more than $10\%$ of the mass of its host galaxy, naturally explaining the overmassive SMBHs discovered by JWST at $z > 6$.

Numerical simulations have shown that the strength of planetary magnetic fields depends on the convective energy flux emerging from planetary interiors. Here we model the interior structure of gas giant planets using \texttt{MESA}, to determine the convective energy flux that can drive the generation of magnetic field. This flux is then incorporated in the Christensen et al. dynamo formalism to estimate the maximum dipolar magnetic field $B^\mathrm{(max)}_\mathrm{dip}$ of our simulated planets. First, we explore how the surface field of intensely irradiated hot Jupiters ($\sim 300 M_\oplus$) and hot Neptunes ($\sim 20 M_\oplus$) evolve as they age. Assuming an orbital separation of 0.1 au, for the hot Jupiters, we find that $B^\mathrm{(max)}_\mathrm{dip}$ evolves from 240 G at 500 Myr to 120 G at 5~Gyr. For hot Neptunes, the magnetic field evolves from 11 G at young ages and dies out at $\gtrsim$ 2 Gyr. Furthermore, we also investigate the effects of atmospheric mass fraction, atmospheric evaporation, orbital separations $\alpha$ and additional planetary masses on the derived $B^\mathrm{(max)}_\mathrm{dip}$. We found that $B^\mathrm{(max)}_\mathrm{dip}$ increases with $\alpha$ for very close-in planets and plateaus out after that. Higher atmospheric mass fractions lead in general to stronger surface fields, because they allow for more extensive dynamo regions and stronger convection.

Despite the energetic significance of Lyman-alpha (Ly{\alpha}; 1216Å) emission from solar flares, regular observations of flare related Ly{\alpha} have been relatively scarce until recently. Advances in instrumental capabilities and a shift in focus over previous Solar Cycles mean it is now routinely possible to take regular co-observations of Ly{\alpha} emission in solar flares. Thus, it is valuable to examine how the instruments selected for flare observations may influence the conclusions drawn from the analysis of their unique measurements. Here, we examine three M-class flares each observed in Ly{\alpha} by GOES-14/EUVS-E, GOES-15/EUVS-E, or GOES-16/EXIS-EUVS-B, and at least one other instrument from PROBA2/LYRA, MAVEN/EUVM, ASO-S/LST-SDI, and SDO/EVE-MEGS-P. For each flare, the relative and excess flux, contrast, total energy, and timings of the Ly{\alpha} emission were compared between instruments. It was found that while the discrepancies in measurements of the relative flux between instruments may be considered minimal, the calculated contrasts, excess fluxes, and energetics may differ significantly - in some cases up to a factor of five. This may have a notable impact on multi instrument investigations of the variable Ly{\alpha} emission in solar flares and estimates of the contribution of Ly{\alpha} to the radiated energy budget of the chromosphere. The findings presented in this study will act as a guide for the interpretation of observations of flare-related Ly{\alpha} from upcoming instruments during future Solar Cycles and inform conclusions drawn from multi-instrument studies.

Solar energetic particles (SEPs) associated with solar flares and coronal mass ejections (CMEs) are key agents of space weather phenomena, posing severe threats to spacecraft and astronauts. Recent observations by Parker Solar Probe (PSP) indicate that the magnetic flux ropes of a CME can trap energetic particles and act as barriers, preventing other particles from crossing. In this paper, we introduce the novel COCONUT+PARADISE model to investigate the confinement of energetic particles within a flux rope and the effects of cross-field diffusion (CFD) on particle transport in the solar corona, particularly in the presence of a CME. Using the global magnetohydrodynamic coronal model COCONUT, we generate background configurations containing a CME modeled as a Titov-Démoulin flux rope (TDFR). We then utilize the particle transport code PARADISE to inject monoenergetic 100 keV protons inside one of the TDFR legs near its footpoint and evolve the particles through the COCONUT backgrounds. To study CFD, we employ two different approaches regarding the perpendicular proton mean free path (MFP): a constant MFP and a Larmor radius-dependent MFP. We contrast these results with those obtained without CFD. While particles remain fully trapped within the TDFR without CFD, we find that even relatively small perpendicular MFP values allow particles on the outer layers to escape. In contrast, the initially interior trapped particles stay largely confined. Finally, we highlight how our model and this paper's results are relevant for future research on particle acceleration and transport in an extended domain encompassing both the corona and inner heliosphere.

Propagation of interplanetary (IP) shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here we address effects of the ambient solar wind on the propagation of two similar CME-driven shocks from the Sun to Earth. The two shock events (CME03: April 3, 2010 and CME12: July 12, 2012) have the following properties: Both events (1) were driven by a halo CME (i.e., source location is near the Sun-Earth line), (2) had a CME source in the southern hemisphere, (3) had a similar transit time (~2 days) to Earth, (4) occurred in a non-quiet solar period, and (5) led to a severe geomagnetic storm. The initial (near the Sun) propagation speed, as measured by coronagraph images, was slower (by ~300 km/s) for CME03 than CME12, but it took about the same amount of traveling time for both events to reach Earth. According to the in-situ solar wind observations from the Wind spacecraft, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12-driven shock. This is also demonstrated in our global MHD simulations. Analysis of our simulation result indicates that the drag force indirectly plays an important role in the shock propagation. The present study suggests that in addition to the initial CME propagation speed near the Sun the shock speed (in the inertial frame) and the ambient solar wind condition, in particular the solar wind speed, are the key to timing the arrival of CME-driven-shock events.

We investigate the possibility that primordial black holes (PBHs) can be formed from large curvature perturbations generated during the waterfall phase transition in a hybrid inflation model driven by an axion-like particle (ALP) $\phi$. The model predicts a spectral index $n_s \simeq 0.964$ and a tensor-to-scalar ratio $r \simeq 0.003$, in agreement with Planck data and potentially testable by next generation cosmic microwave background (CMB) experiments such as CMB-S4 and LiteBIRD. We find that the PBH mass and the peak of the associated scalar-induced gravitational wave (SIGW) spectrum are correlated with the ALP mass. In particular, PBHs in the mass range $10^{-13}\, M_\odot$ can constitute either the entire dark matter (DM) content of the universe or a significant fraction of it. The predicted second-order GWs from this mechanism are within the sensitivity reach of future observatories like LISA and ET. The typical reheating temperature in the model is around $10^6 - 10^7$ GeV is consistent with Big Bang Nucleosynthesis (BBN) constraints.