Papers for Wednesday, Jul 24 2024

We report new branching fraction measurements for 224 ultraviolet (UV) and optical transitions of Tm II. These transitions range in wavelength (wavenumber) from 2350 - 6417 Angstroms (42532 - 15579 cm-1) and originate in 13 odd-parity and 24 even-parity upper levels. Thirty-five of the 37 levels, accounting for 213 of the 224 transitions, are studied for the first time. Branching fractions are determined for two levels studied previously for comparison to earlier results. The levels studied for the first time are high-lying, ranging in energy from 35753 - 54989 cm-1. The branching fractions are determined from emission spectra from two different high-resolution spectrometers. These are combined with radiative lifetimes reported in an earlier study to produce a set of transition probabilities and log(gf) values with accuracy ranging from 5 - 30%. Comparison is made to experimental and theoretical transition probabilities from the literature where such data exist. These new log(gf) values are used to derive an abundance from one previously unused Tm II line in the UV spectrum of the r-process-enhanced metal-poor star HD 222925, and this abundance is consistent with previous determinations based on other Tm II lines.

JWST has revealed a population of low-luminosity AGN at $z>4$ in compact, red hosts (the "Little Red Dots", or LRDs), which are largely undetected in X-rays. We investigate this phenomenon using GRRMHD simulations of super-Eddington accretion onto a SMBH with $M_\bullet=10^7 \,\rm M_\odot$ at $z\sim6$, representing the median population; the SEDs that we obtain are intrinsically X-ray weak. The highest levels of X-ray weakness occur in SMBHs accreting at mildly super-Eddington rates ($1.4<f_{\rm Edd}<4$) with zero spin, viewed at angles $>30^\circ$ from the pole. X-ray bolometric corrections in the observed $2-10$ keV band reach $\sim10^4$ at $z=6$, $\sim5$ times higher than the highest constraint from X-ray stacking. Most SEDs exhibit $\alpha_{\rm ox}$ values outside standard ranges, with X-ray weakness increasing with optical-UV luminosity; they are also extraordinarily steep and soft in the X-rays (median photon index $\Gamma=3.1$, mode of $\Gamma=4.4$). SEDs strong in the X-rays have harder spectra with a high-energy bump when viewed near the hot ($>10^8$ K) and highly-relativistic jet, whereas X-ray weak SEDs lack this feature. Viewing a SMBH within $10^\circ$ of its pole, where beaming enhances the X-ray emission, has a $\sim1.5\%$ probability, matching the LRD X-ray detection rate. Next-generation observatories like AXIS will detect X-ray weak LRDs at $z\sim6$ from any viewing angle. Although many SMBHs in the LRDs are already estimated to accrete at super-Eddington rates, our model explains $50\%$ of their population by requiring that their masses are overestimated by a mere factor of $\sim3$. In summary, we suggest that LRDs host slowly spinning SMBHs accreting at mildly super-Eddington rates, with large covering factors and broad emission lines enhanced by strong winds, providing a self-consistent explanation for their X-ray weakness and complementing other models.

This study aims to assess the potential of the upcoming PLATO mission to investigate exoplanet populations around stars in diverse Galactic environments, specifically focusing on the Milky Way thin disk, thick disk, and stellar halo. We aim to quantify PLATOs ability to detect planets in each environment and determine how these observations could constrain planet formation models. Beginning from the all-sky PLATO Input Catalog, we kinematically classify the 2.4 million FGK stars into their respective Galactic components. For the sub-sample of stars in the long-observation LOPS2 and LOPN1 PLATO fields, we estimate planet occurrence rates using the New Generation Planet Population Synthesis (NGPPS) dataset. Combining these estimates with a PLATO detection efficiency model, we predicted the expected planet yields for each Galactic environment during a nominal 2+2 year mission. Based on our analysis, PLATO is likely to detect at least 400 exoplanets around the alpha-enriched thick disk stars. The majority of those planets are expected to be Super-Earths and Sub-Neptunes with radii between 2 and 10 Earth radii and orbital periods between 2 and 50 days, ideal for studying the link between the radius valley and stellar chemistry. For the metal-poor halo, PLATO is likely to detect between 1 and 80 planets with periods between 10 and 50 days, depending on the potential existence of a metallicity threshold for planet formation. The PLATO fields contain more than 3,400 potential target stars with [Fe/H] < -0.6, which will help to improve our understanding of planets around metal-poor stars. We identify a specific target list of 47 (kinematically classified) halo stars in the high-priority, high-SNR PLATO P1 sample, offering prime opportunities in the search for planets in metal-poor environments.

NGC~6558 is a low-galactic latitude globular cluster projected in the direction of the Galactic bulge. Due to high reddening, this region presents challenges in deriving accurate parameters, which require meticulous photometric analysis. We present a combined analysis of near-infrared and optical photometry from multi-epoch high-resolution images collected with Gemini-South/GSAOI+GeMS (in the $J$ and $K_S$ filters) and HST/ACS (in the F606W and F814W filters). We aim to refine the fundamental parameters of NGC~6558, utilizing high-quality Gemini-South/GSAOI and HST/ACS photometries. Additionally, we intend to investigate its role in the formation of the Galactic bulge. We studied the impact of two differential reddening corrections on the age derivation. When removing as much as possible the Galactic bulge field star contamination, the isochrone fitting combined with synthetic colour-magnitude diagrams gives a distance of $8.41^{+0.11}_{-0.10}$ kpc, an age of $13.0\pm 0.9$ Gyr, a reddening of E($B-V$)$\,\,=0.34\pm0.02$, and a total-to-selective coefficient R$_V = 3.2\pm0.2$ thanks to the simultaneous near-infrared$-$Optical synthetic colour-magnitude diagram fitting. The orbital parameters showed that NGC~6558 is confined whitin the inner Galaxy and it is not compatible with a bar-shape orbit, indicating that it is a bulge member. The old age of NGC~6558, combined with similar metallicity and a blue horizontal branch in the Galactic bulge, indicates that it is part of the moderately metal-poor globular clusters. Assembling the old and moderately metal-poor ([Fe/H]$\,\,\sim-1.1$) clusters in the Galactic bulge, we derived their age-metallicity relation with star formation stars at $13.6\pm0.2$ Gyr and effective yields of $\rho=0.007\pm0.009\,\, Z_\odot$ showing a chemical enrichment ten times faster than the ex-situ globular clusters branch.

Hydrogen lines from forming planets are crucial for understanding planet formation. However, the number of planetary hydrogen line detections is still limited. Recent JWST/NIRSpec observations have detected Paschen and Brackett hydrogen lines at TWA 27 B (2M1207b). TWA 27 B is classified as a planetary-mass companison (PMC) rather than a planet due to its large mass ratio to the central object ($\approx 5 M_\mathrm{J}$ compared to $25 M_\mathrm{J}$). Nevertheless, TWA 27 B's hydrogen line emission is expected to be same as for planets, given its small mass. We aim to constrain the accretion properties and accretion geometry of TWA 27 B, contributing to our understanding of hydrogen line emission mechanism common to both PMCs and planets. We conduct spectral fitting of four bright hydrogen lines (Pa-$\alpha$, Pa-$\beta$, Pa-$\gamma$, Pa-$\delta$) with an accretion-shock emission model tailored for forming planets. We estimate the mass accretion rate at $\dot{M} \approx 3 \times 10^{-9}\, M_\mathrm{J}\,\mathrm{yr}^{-1}$ with our fiducial parameters, though this is subject to an uncertainty of up to factor of ten. Our analysis also indicates a dense accretion flow, $n\gtrsim 10^{13}\,\mathrm{cm^{-3}}$ just before the shock, implying a small accretion-shock filling factor $f_\mathrm{f}$ on the planetary surface ($f_\mathrm{f} \lesssim 5\times10^{-4}$). This finding suggests that magnetospheric accretion is occurring at TWA 27 B. Additionally, we carry out a comparative analysis of hydrogen-line emission color to identify the emission mechanism, but the associated uncertainties proved too large for definitive conclusions. This underscores the need for further high-precision observational studies to elucidate these emission mechanisms fully.

Type Ia supernovae (SNe Ia) are thermonuclear exploding stars that can be used to put constraints on the nature of our universe. One challenge with population analyses of SNe Ia is Malmquist bias, where we preferentially observe the brighter SNe due to limitations of our telescopes. If untreated, this bias can propagate through to our posteriors on cosmological parameters. In this paper, we develop a novel technique of using a normalising flow to learn the non-analytical likelihood of observing a SN Ia for a given survey from simulations, that is independent of any cosmological model. The learnt likelihood is then used in a hierarchical Bayesian model with Hamiltonian Monte Carlo sampling to put constraints on different sets of cosmological parameters conditioned on the observed data. We verify this technique on toy model simulations finding excellent agreement with analytically-derived posteriors to within $1 \sigma$.

We perform axisymmetric two-dimensional radiation-hydrodynamic simulations of super-Eddington accretion flow and outflow around black holes to examine the properties of radiation and outflow as functions of the black hole mass and the accretion rate onto the black hole ($\dot M_{\rm BH}$). We find that the $\dot{m}_{\rm BH} (\equiv \dot{M}_{\rm BH}c^2 /L_{\rm Edd})$ dependence of $L_{\rm rad}/L_{\rm Edd}$ and $L_{\rm mech}/L_{\rm Edd}$ found for stellar-mass black hole can apply to the high mass cases, where $L_{\rm rad}$ is the radiation luminosity, $L_{\rm mech}$ is the mechanical luminosity, $c$ is the speed of light, and $L_{\rm Edd}$ is the Eddington luminosity. Such universalities can appear in the regime, in which electron scattering opacity dominates over absorption opacity. Further, the normalized isotropic mechanical luminosity $L_{\rm mech}^{\rm ISO}/L_{\rm Edd}$ (evaluated by normalized density and velocity at $\theta=10^\circ$) exhibits a broken power-law relationship with ${\dot m}_{\rm BH}$; $L_{\rm mech}^{\rm ISO}/ L_{\rm Edd} \propto{\dot m}_{\rm BH}^{2.7}$ (or $\propto {\dot m}_{\rm BH}^{0.7}$) below (above) ${\dot m}_{\rm BH}\sim 400$. This is because the radial velocity stays nearly constant (or even decreases) below (above) the break with increase of $\dot m_{\rm BH}$. We also find that the luminosity ratio is $L_{\rm mech}/L_{\rm rad}^{\rm ISO} \sim$ 0.05 at ${\dot m}_{\rm BH} \sim 100$, which is roughly consistent with the observations of NLS1, 1H 0323+103.

Recent results of the event horizon-scale images of M87* and Sagittarius A* from the Event Horizon Telescope Collaboration show that strong magnetic fields are likely present around the central black holes (BHs) in these sources. Magnetically arrested disks (MADs), the end stage of magnetic flux saturation around BHs, are especially rich in horizon-scale physics due to the presence of powerful jets and magnetic flux eruptions that provide significant feedback on the accretion mechanism. Here, we present an overview of our current knowledge about the magnetic field evolution in numerical simulations of accreting BHs, focusing on jet launching, black hole-interstellar medium feedback, and black hole imaging of MADs. We find that misaligned MAD accretion flows seemingly exhibit jet ejection cycles that could produce flaring states in radio-quiet active galactic nuclei. Further, we show that advances in horizon-scale interferometric telescopes could identify disk misalignment by imaging the disk-jet connection region.

Star formation rate (SFR) is a fundamental parameter for describing galaxies and inferring their evolutionary course. HII regions yield the best measure of instantaneous SFR in galaxies, although the derived SFR can have large uncertainties depending on tracers and assumptions. We present an SFR calibration for the entire molecular gas disk of the nearby Seyfert galaxy NGC 1068, based on our new high-sensitivity ALMA 100GHz continuum data at 55pc (=0."8) resolution in combination with the HST Pa{\alpha} line data. In this calibration, we account for the spatial variations of dust extinction, electron temperature of HII regions, AGN contamination, and diffuse ionized gas (DIG) based on publicly available multi-wavelength data. Especially, given the extended nature and the possible non-negligible contribution to the total SFR, a careful consideration of DIG is essential. With a cross-calibration between two corrected ionized gas tracers (free-free continuum&Pa{\alpha}), the total SFR of the NGC 1068 disk is estimated to be 3.2\pm0.5 Msol/yr, one-third of the SFR without accounting for DIG (9.1\pm1.4 Msol/yr). We confirmed high SFR around the southern bar-end and the corotation radius, which is consistent with the previous SFR measurements. In addition, our total SFR exceeds the total SFR based on 8{\mu}m dust emission by a factor of 1.5. We attribute this discrepancy to the differences in the young stars at different stages of evolution traced by each tracer and their respective timescales. This study provides an example to address the various uncertainties in conventional SFR measurements and their potential to lead to significant SFR miscalculations.

In close binary star systems, common envelope evolution may occur after a previous phase of mass transfer. Some isolated formation channels for double neutron star binaries suggest that the donor of common envelope evolution was the accretor of a previous phase of stable mass transfer. Accretion should substantially alter the structure of the donor, particularly by steepening the density gradient at the core-envelope interface and rejuvenating the star. We study the common envelope evolution of a donor that was the accretor of a previous phase of stable mass transfer and has a rejuvenated structure. We perform 3D hydrodynamics simulations of the common envelope evolution of a 18 $M_\odot$ supergiant with a 1.4 $M_\odot$ companion using rejuvenated and non-rejuvenated 1D stellar models for the donor. We compare the two simulations to characterize the effect of the rejuvenation on the outcome of the common envelope phase and the shape of the ejecta. We find that accounting for a previous phase of mass transfer reduces the duration of the inspiral phase by a factor of two, likely due to the different structure in the outer layers of the donor. In the rejuvenated case, the simulations show more equatorially concentrated and asymmetric ejecta, though both cases display evidence for the formation of a pressure-supported thick circumbinary disk. During the dynamical inspiral phase, the impact of rejuvenation on the unbinding of the envelope is unclear; we find that rejuvenation decreases the amount of unbound mass by 20$\%$ to 40$\%$ depending on the energy criterion used.

A major aim of current and upcoming cosmological surveys is testing deviations from the standard $\Lambda$CDM model, but the full scientific value of these surveys will only be realised through efficient simulation methods that keep up with the increasing volume and precision of observational data. $N$-body simulations of modified gravity (MG) theories are computationally expensive since highly non-linear equations need to be solved to model the non-linear matter evolution; this represents a significant bottleneck in the path to reach the data volume and resolution attained by equivalent $\Lambda$CDM simulations. We develop a field-level, neural-network-based emulator that generates density and velocity divergence fields under the $f(R)$ gravity MG model from the corresponding $\Lambda$CDM simulated fields. Using attention mechanisms and a complementary frequency-based loss function, our model is able to learn this intricate mapping. We further use the idea of latent space extrapolation to generalise our emulator to $f(R)$ models with differing field strengths. The predictions of our emulator agree with the $f(R)$ simulations to within 5% for matter density and to within 10% for velocity divergence power spectra up to $k \sim 2\,h$ $\mathrm{Mpc}^{-1}$. But for a few select cases, higher-order statistics are reproduced with $\lesssim$10% agreement with the $f(R)$ simulations. Latent extrapolation allows our emulator to generalise to different $f(R)$ model variants without explicitly training on those variants. Given a $\Lambda$CDM simulation, the GPU-based emulator is able to reproduce the equivalent $f(R)$ realisation $\sim$600 times faster than full $N$-body simulations. This lays the foundations for a valuable tool for realistic yet rapid mock field generation and robust cosmological analyses.

The origin of Phobos and Deimos remains unknown. They are typically thought either to be captured asteroids or to have accreted from a debris disk produced by a giant impact. Here, we present an alternative scenario wherein fragments of a tidally disrupted asteroid are captured and evolve into a collisional proto-satellite disk. We simulate the initial disruption and the fragments' subsequent orbital evolution. We find that tens of percent of an unbound asteroid's mass can be captured and survive beyond collisional timescales, across a broad range of periapsis distances, speeds, masses, spins, and orientations in the Sun--Mars frame. Furthermore, more than one percent of the asteroid's mass could evolve to circularise in the moons' accretion region. The resulting lower mass requirement for the parent body than that for a giant impact could increase the likelihood of this route to forming a proto-satellite disk that, unlike direct capture, could also naturally explain the moons' orbits. These formation scenarios imply different properties of Mars's moons to be tested by upcoming spacecraft missions.

The Mid-Infrared Instrument (MIRI)'s Medium Resolution Spectrometer (the MRS) on JWST has potentially important advantages for transit and eclipse spectroscopy of exoplanets, including lack of saturation for bright host stars, wavelength span to longward of 20 microns, and JWST's highest spectral resolving power. We here test the performance of the MRS for time series spectroscopy by observing the secondary eclipse of the bright stellar eclipsing binary R Canis Majoris. Our observations push the MRS into saturation at the shortest wavelength, more than for any currently known exoplanet system. We find strong charge migration between pixels that we mitigate using a custom data analysis pipeline. Our data analysis recovers much of the spatial charge migration by combining detector pixels at the group level, via weighting by the point spread function. We achieve nearly photon-limited performance in time series data at wavelengths longward of 5.2 microns. In 2017, Snellen et al. suggested that the MRS could be used to detect carbon dioxide absorption from the atmosphere of the temperate planet orbiting Proxima Centauri. We infer that the relative spectral response of the MRS versus wavelength is sufficiently stable to make that detection feasible. As regards the secondary eclipse of this Algol-type binary, we measure the eclipse depth by summing our spectra over the wavelengths in four channels, and also measuring the eclipse depth as observed by TESS. Those eclipse depths require a temperature for the secondary star that is significantly hotter than previous observations in the optical to near-IR, probably due to irradiation by the primary star. At full spectral resolution of the MRS, we find atomic hydrogen recombination emission lines in the secondary star, from principal quantum levels n = 7, 8, 10, and 14.

We study the stellar properties of a sample of simulated ultra-diffuse galaxies (UDGs) with stellar mass $M_\star=10^{7.5}$ - $10^{9} ~ \rm{M_{\odot}}$, selected from the TNG50 simulation, where UDGs form mainly in high-spin dwarf-mass halos. We divide our sample into star-forming and quenched UDGs, finding good agreement with the stellar assembly history measured in observations. Star-forming UDGs and quenched UDGs with $M_\star \geq 10^8\; \rm M_\odot$ in our sample are particularly inefficient at forming stars, having $2$ - $10$ times less stellar mass than non-UDGs for the same virial mass halo. These results are consistent with recent mass inferences in UDG samples and suggest that the most inefficient UDGs arise from a late assembly of the dark matter mass followed by a stellar growth that is comparatively slower (for star-forming UDGs) or that was interrupted due to environmental removal of the gas (for quenched UDGs). Regardless of efficiency, UDGs are $60\%$ poorer in [Fe/H] than the population of non-UDGs at a fixed stellar mass, with the most extreme objects having metal content consistent with the simulated mass-metallicity relation at $z \sim 2$. Quenched UDGs stop their star formation in shorter timescales than non-UDGs of similar mass and are, as a consequence, alpha-enhanced with respect to non-UDGs. We identify metallicity profiles in UDGs as a potential avenue to distinguish between different formation paths for these galaxies, where gentle formation as a result of high-spin halos would present well-defined declining metallicity radial profiles while powerful-outflows or tidal stripping formation models would lead to flatter or constant metallicity as a function of radius due

Gamma-ray bursts (GRBs) brighter than the GRB 221009A, the brightest yet observed, have previously been estimated to occur at a rate of 1 per 10,000 years, based on the extrapolation of the distribution of fluences of the Long GRB population. We show that bursts this bright could instead have a rate as high as approximately one per 200 years if they are from a separate population of narrow-jet GRBs. This population must have a maximum redshift of about $z\approx 0.38$ in order to avoid over-producing the observed rate of fainter GRBs. We show that it will take $> 100$ years to confirm this new population based on observing another GRB from it with a $\gamma$-ray detector; observing an orphan optical afterglow from this population with Vera Rubin Observatory or an orphan radio afterglow with the Square Kilometer Array will also take similarly long times to observe, and it is unclear if they could be distinguished from the standard GRB population. We show that the nearby narrow-jet population has more favorable energetics for producing ultra-high energy cosmic rays than standard GRBs. The rate of bursts in the Milky Way bright enough to cause mass extinctions of life on Earth from the narrow jet population is estimated to be approximately 1 per 500 Myr. This GRB population could make life in the Milky Way less likely, with implications for future searches for life on exoplanets.

The presence of dark gaps, a preferential light deficit along the bar minor axis, is observationally well known. The properties of dark gaps are thought to be associated with the properties of bars, and their spatial locations are often associated with bar resonances. However, a systematic study, testing the robustness and universality of these assumptions, is still largely missing. Here, we investigate the formation and evolution of bar-induced dark gaps using a suite of N-body models of (kinematically cold) thin and (kinematically hot) thick discs with varying thick disc mass fraction, and different thin-to-thick disc geometry. We find that dark gaps are a natural consequence of the trapping of disc stars by the bar. The properties of dark gaps (such as strength and extent) are well correlated with the properties of bars. For stronger dark gaps, the fractional mass loss along the bar minor axis can reach up to ~60-80 percent of the initial mass contained, which is redistributed within the bar. These trends hold true irrespective of the mass fraction in the thick disc and the assumed disc geometry. In all our models harbouring slow bars, none of the resonances (corotation, Inner Lindblad resonance, and 4:1 ultra-harmonic resonance) associated with the bar correspond to the location of dark gaps, thereby suggesting that the location of dark gaps is not a universal proxy for these bar resonances, in contrast with earlier studies.

The sensitivity and spectral coverage of JWST is enabling us to test our assumptions of ultracool dwarf atmospheric chemistry, especially with regards to the abundances of phosphine (PH$_3$) and carbon dioxide (CO$_2$). In this paper, we use NIRSpec PRISM spectra ($\sim$0.8$-$5.5 $\mu$m, $R\sim$100) of four late T and Y dwarfs to show that standard substellar atmosphere models have difficulty replicating the 4.1$-$4.4 $\mu$m wavelength range as they predict an overabundance of phosphine and an underabundance of carbon dioxide. To help quantify this discrepancy, we generate a grid of models using PICASO based on the Elf Owl chemical and temperature profiles where we include the abundances of these two molecules as parameters. The fits to these PICASO models show a consistent preference for orders of magnitude higher CO$_2$ abundances and a reduction in PH$_3$ abundance as compared to the nominal models. This tendency means that the claimed phosphine detection in UNCOVER$-$BD$-$3 could instead be explained by a CO$_2$ abundance in excess of standard atmospheric model predictions; however the signal-to-noise of the spectrum is not high enough to discriminate between these cases. We discuss atmospheric mechanisms that could explain the observed underabundance of PH$_3$ and overabundance of CO$_2$, including a vertical eddy diffusion coefficient ($K_{\mathrm{zz}}$) that varies with altitude, incorrect chemical pathways, or elements condensing out in forms such as NH$_4$H$_2$PO$_4$. However, our favored explanation for the required CO$_2$ enhancement is that the quench approximation does not accurately predict the CO$_2$ abundance, as CO$_2$ remains in chemical equilibrium with CO after CO quenches.

The study of the chemical composition of the interstellar medium (ISM) requires a strong synergy between laboratory astrophysics, modeling, and observations. In particular, astrochemical models have been developed for decades now and include an increasing number of processes studied in the laboratory or theoretically. These models follow the chemistry both in the gas phase and at the surface of interstellar grains. Since 2012, we have provided complete gas-phase chemical networks for astrochemical codes that can be used to model various environments of the ISM. Our aim is to introduce the new up-to-date astrochemical network kida.uva.2024 together with the ice chemical network and the fortran code to compute time dependent compositions of the gas, the ice surface, and the ice mantles under physical conditions relevant for the ISM. The gas-phase chemical reactions, as well as associated rate coefficients, included in kida.uva.2024 were carefully selected from the KIDA online database and represent the most recent values. The model predictions for cold core conditions and for when considering only gas-phase processes were computed as a function of time and compared to the predictions obtained with the previous version, kida.uva.2014. In addition, key chemical reactions were identified. The model predictions, including both gas and surface processes, were compared to the molecular abundances as observed in the cold core TMC1-CP. Many gas-phase reactions were revised or added to produce kida.uva.2024. The new model predictions are different by several orders of magnitude for some species. The agreement of this new model with observations in TMC-1 (CP) is, however, similar to the one obtained with the previous network.

The clouds have a great impact on Venus's energy budget and climate evolution, but its three-dimensional structure is still not well understood. Here we incorporate a simple Venus cloud physics scheme into a flexible GCM to investigate the three-dimensional cloud spatial variability. Our simulations show good agreement with observations in terms of the vertical profiles of clouds and H2SO4 vapor. H2O vapor is overestimated above the clouds due to efficient transport in the cloud region. The cloud top decreases as latitude increases, qualitatively consistent with Venus Express observations. The underlying mechanism is the combination of H2SO4 chemical production and meridional circulation. The mixing ratios of H2SO4 at 50-60 km and H2O vapors in the main cloud deck basically exhibit maxima around the equator, due to the effect of temperature's control on the saturation vapor mixing ratios of the two species. The cloud mass distribution is subject to both H2SO4 chemical production and dynamical transport and shows a pattern that peaks around the equator in the upper cloud while peaks at mid-high latitudes in the middle cloud. At low latitudes, H2SO4 and H2O vapors, cloud mass loading and acidity show semidiurnal variations at different altitude ranges, which can be validated against future missions. Our model emphasizes the complexity of the Venus climate system and the great need for more observations and simulations to unravel its spatial variability and underlying atmospheric and/or geological processes.

We present new free-form and hybrid mass reconstructions of the galaxy cluster lens MACS J0416.1-2403 at $z=0.396$ using the lens inversion method GRALE. The reconstructions use 237 spectroscopically confirmed multiple images from Bergamini et. al. 2023 as the main input. Our primary model reconstructs images to a positional accuracy of 0.191", thus representing one of the most precise reconstructions of this lens to date. Our models find broad agreement with previous reconstructions, and identify two $\sim 10^{11} M_{\odot}$ light-unaffiliated substructures. We focus on two highly magnified arcs: Spock and Mothra. Our model features a unique critical curve structure around the Spock arc with 2 crossings. This structure enables sufficient magnification across this arc to potentially explain the large number of transients as microlensing events of supergiant stars. Additionally, we develop a model of the millilens substructure expected to be magnifying Mothra, which may be a binary pair of supergiants with $\mu \sim 6000$. This model accounts for flexibility in the millilens position while preserving the observed flux and minimizing image position displacements along the Mothra arc. We constrain the millilens mass and core radius to $\lesssim 10^6 M_{\odot}$ and $\lesssim 12$ pc, respectively, which would render it one of the smallest and most compact substructures constrained by lensing. If the millilens is dominated by wave dark matter, the axion mass is constrained to be $< 3.0 \times 10^{-21}$ eV. Further monitoring of this lens with JWST will uncover more transients, permitting tighter constraints on the structure surrounding these two arcs.

Close-in planets smaller than Neptune form two distinct populations composed of rocky super-Earths and sub-Neptunes that may host primordial H/He envelopes. The origin of the radius valley separating these two planet populations remains an open question and has been posited to emerge either directly from the planet formation process or via subsequent atmospheric escape. Multi-transiting systems that span the radius valley are known to be useful diagnostics of XUV-driven mass loss. Here, we extend this framework to test XUV-driven photoevaporation, core-powered mass loss, and an accretion-limited primordial radius valley model. Focusing on multi-transiting systems allows us to eliminate unobservable quantities that are shared within individual systems such as stellar XUV luminosity histories and the properties of the protoplanetary disk. We test each proposed radius valley emergence mechanism on all 221 known multi-transiting systems and calculate the minimum masses of the systems' enveloped planets to be consistent with the models. We compare our model predictions to 75 systems with measured masses and find that the majority of systems can be explained by any of the three proposed mechanisms. We also examine model consistency as a function of stellar mass and stellar metallicity but find no significant trends. More multi-transiting systems with mass characterizations are required before multi-transiting systems can serve as a viable diagnostic of radius valley emergence models. Our software for the model evaluations presented herein is available on GitHub and may be applied to future multi-transiting system discoveries.

The 16 Myr-old A0V star HD 156623 in the Scorpius--Centaurus association hosts a high-fractional-luminosity debris disk, recently resolved in scattered light for the first time by the Gemini Planet Imager (GPI) in polarized intensity. We present new analysis of the GPI H-band polarimetric detection of the HD 156623 debris disk, with particular interest in its unique morphology. This debris disk lacks a visible inner clearing, unlike the majority of low-inclination disks in the GPI sample and in Sco-Cen, and it is known to contain CO gas, positioning it as a candidate ``hybrid'' or ``shielded'' disk. We use radiative transfer models to constrain the geometric parameters of the disk based on scattered light data and thermal models to constrain the unresolved inner radius based on the system's spectral energy distribution (SED). We also compute a measurement of the polarized scattering phase function, adding to the existing sample of empirical phase function measurements. We find that HD 156623's debris disk inner radius is constrained to less than 26.6 AU from scattered light imagery and less than 13.4 AU from SED modeling at a 99.7% confidence interval, and suggest that gas drag may play a role in retaining sub-blowout size dust grains so close to the star.

Binary neutron star mergers play an important role in nuclear astrophysics: their gravitational wave and electromagnetic signals carry information about the equation of state of cold matter above nuclear saturation density, and they may be one of the main sources of r-process elements in the Universe. Neutrino-matter interactions during and after merger impact the properties of these electromagnetic signals, and the relative abundances of the produced r-process elements. Existing merger simulations are however limited in their ability to realistically model neutrino transport and neutrino-matter interactions. Here, we perform a comparison of the impact of the use of state-of-the art two-moment or Monte-Carlo transport schemes on the outcome of merger simulations, for a single binary neutron star system with a short-lived neutron star remnant ($(5-10)\,{\rm ms}$). We also investigate the use of different reaction rates in the simulations. While the best transport schemes generally agree well on the qualitative impact of neutrinos on the system, differences in the behavior of the high-density regions can significantly impact the collapse time and the properties of the hot tidal arms in this metastable merger remnant. The chosen interaction rates, transport algorithm, as well as recent improvements by Radice et al to the two-moment algorithms can all contribute to changes at the $(10-30)\%$ level in the global properties of the merger remnant and outflows. The limitations of previous moment schemes fixed by Radice et al also appear sufficient to explain the large difference that we observed in the production of heavy-lepton neutrinos in a previous comparison of Monte-Carlo and moment schemes in the context of a low mass binary neutron star system.

A small number of pulsars are known to emit giant pulses, single pulses much brighter than average. Among these is PSR J0534+2200, also known as the Crab pulsar, a young pulsar with high giant pulse rates. Long-term monitoring of the Crab pulsar presents an excellent opportunity to perform statistical studies of its giant pulses and the processes affecting them, potentially providing insight into the behavior of other neutron stars that emit bright single pulses. Here, we present an analysis of a set of 24,985 Crab giant pulses obtained from 88 hours of daily observations at a center frequency of 1.55 GHz by the 20-meter telescope at the Green Bank Observatory, spread over 461 days. We study the effects of refractive scintillation at higher frequencies than previous studies and compare methods of correcting for this effect. We also search for deterministic patterns seen in other single-pulse sources, possible periodicities seen in several rotating radio transients and fast radio bursts, and clustering of giant pulses like that seen in the repeating fast radio burst FRB121102.

We compare two-moment based \emph{energy-dependent} and 3 variants of \emph{energy-integrated} neutrino transport general-relativistic magnetohydrodynamics simulations of hypermassive neutron star. To study the impacts due to the choice of the neutrino transport schemes, we perform simulations with the same setups and input neutrino microphysics. We show that the main differences between energy-dependent and energy-integrated neutrino transport are found in the disk and ejecta properties, as well as in the neutrino signals. The properties of the disk surrounding the neutron star and the ejecta in energy-dependent transport are very different from the ones obtained using energy-integrated schemes. Specifically, in the energy-dependent case, the disk is more neutron-rich at early times, and becomes geometrically thicker at later times. In addition, the ejecta is more massive, and on average more neutron-rich in the energy-dependent simulations. Moreover, the average neutrino energies and luminosities are about 30\% higher. Energy-dependent neutrino transport is necessary if one wants to better model the neutrino signals and matter outflows from neutron star merger remnants via numerical simulations.

The efficiency of science observation Short-Term Scheduling (STS) can be defined as being a function of how many highly ranked observations are completed per unit time. Current STS at ESO's Paranal observatory is achieved through filtering and ranking observations via well-defined algorithms, leading to a proposed observation at time t. This Paranal STS model has been successfully employed for more than a decade. Here, we summarise the current VLT(I) STS model, and outline ongoing efforts of optimising the scientific return of both the VLT(I) and future ELT. We describe the STS simulator we have built that enables us to evaluate how changes in model assumptions affect STS effectiveness. Such changes include: using short-term predictions of atmospheric parameters instead of assuming their constant time evolution; assessing how the ranking weights on different observation parameters can be changed to optimise the scheduling; changing STS to be more `dynamic' to consider medium-term scheduling constraints. We present specific results comparing how machine learning predictions of the seeing can improve STS efficiency when compared to the current model of using the last 10\,min median of the measured seeing for observation selection.

We utilized photometric data from the space telescope AKARI to identify potential planetary nebulae (PNe) and proto-planetary nebulae (PPNe) candidates. Using the colour-colour diagram, we found a region with a high concentration of established PNe and PPNe, comprising about 95% of the objects. Based on this, we identified 67 objects within this region that lack definitive classification in existing literature, suggesting they are promising candidates. We conducted Spectral Energy Distribution (SED) analysis and morphological investigations using imagery from various observatories and satellites. Finally, we present a list of 65 potential PNe and PPNe candidates.

This paper explores the use of low-dimensional parametric representations of neutron-star equations of state that include discontinuities caused by phase transitions. The accuracies of optimal piecewise-analytic and spectral representations are evaluated for equations of state having first- or second-order phase transitions with a wide range of discontinuity sizes. These results suggest that the piecewise-analytic representations of these non-smooth equations of state are convergent, while the spectral representations are not. Nevertheless, the lower-order (2 <= N_parms <= 7) spectral representations are found to be more accurate than the piecewise-analytic representations with the same number of parameters.

We investigate the impact of relativistic SZ corrections on Planck measurements of massive galaxy clusters, finding that they have a significant impact at the $\approx$5 -- 15% and up to $\approx 3\sigma$ level. We investigate the possibility of constraining temperature directly from these SZ measurements but find that only weak constraints are possible for the most significant detections; for most clusters, an external temperature measurement is required to correctly measure integrated Compton-$y$. We also investigate the impact of profile shape assumptions and find that these have a small but non-negligible impact on measured Compton-$y$, at the $\approx$5% level. Informed by the results of these investigations, we recalibrate the Planck SZ observable-mass scaling relation, using the updated NPIPE data release and a larger sample of X-ray mass estimates. Along with the expected change in the high-mass end of the scaling relation, which does not impact Planck mass estimation, we also find hints of a low-mass deviation but this requires better understanding of the selection function in order to confirm.

Very massive stars are radiation pressure dominated. Before running out of viable nuclear fuel, they can reach a thermodynamic state where electron-positron pair-production robs them of radiation support, triggering their collapse. Thermonuclear explosion(s) in the core ensue. These have long been predicted to result in either repeated episodic mass loss (pulsational pair instability), which reduces the mass available to eventually form a black hole, or, if sufficient energy is generated, the complete unbinding of all stellar material in one single explosive episode (pair instability supernova), which leaves behind no black hole. Despite theoretical agreement among modelers, the wide variety of predicted signatures and the rarity of very high-mass stellar progenitors have so far resulted in a lack of observational confirmation. Nevertheless, because of the impact of pair instability evolution on black hole masses relevant to gravitational-wave astronomy, as well as the present and upcoming expanded capabilities of time-domain astronomy and high redshift spectroscopy, interest in these explosion remains high. We review the current understanding of pair instability evolution, with particular emphasis on the known uncertainties. We also summarize the existing claimed electromagnetic counterparts and discuss prospects for future direct and indirect searches.

Recently, the first pulsating ultraluminous X-ray source M82 X-2 was reported to be experiencing a rapid orbital decay at a rate of $\dot{P}=-(5.69\pm0.24)\times 10^{-8}~\rm s\,s^{-1}$ based on seven years \emph{NuSTAR} data. To account for the observed orbital-period derivative, it requires a mass transfer rate of $\sim200\dot{M}_{\rm edd}$ ($\dot{M}_{\rm edd}$ is the Eddington accretion rate) from the donor star to the accreting neutron star. However, other potential models cannot be completely excluded. In this work, we propose an anomalous magnetic braking (AMB) model to interpret the detected orbital decay of M82 X-2. If the donor star is an Ap/Bp star with an anomalously strong magnetic field, the magnetic coupling between strong surface magnetic field and irradiation-driven wind from the surface of the donor star could cause an efficient angular-momentum loss, driving a rapid orbital decay observed in M82 X-2. The AMB mechanism of an Ap/Bp star with a mass of $5.0-15.0~M_{\odot}$ and a surface magnetic field of $3000-4500~\rm G$ could produce the observed $\dot{P}$ of M82 X-2. We also discuss the possibility of other alternative models including the companion star expansion and a surrounding circumbinary disk.

We present here RadioSED, a Bayesian inference framework tailored to modelling and classifying broadband radio spectral energy distributions (SEDs) using only data from publicly-released, large-area surveys. We outline the functionality of RadioSED, with its focus on broadband radio emissions which can trace kiloparsec-scale absorption within both the radio jets and the circumgalactic medium of Active Galactic Nuclei (AGN). In particular, we discuss the capability of RadioSED to advance our understanding of AGN physics and composition within youngest and most compact sources, for which high resolution imaging is often unavailable. These young radio AGN typically manifest as peaked spectrum (PS) sources which, before RadioSED, were difficult to identify owing to the large, broadband frequency coverage typically required, and yet they provide an invaluable environment for understanding AGN evolution and feedback. We discuss the implementation details of RadioSED, and we validate our approach against both synthetic and observational data. Since the surveys used are drawn from multiple epochs of observation, we also consider the output from RadioSED in the context of AGN variability. Finally, we show that RadioSED recovers the expected SED shapes for a selection of well-characterised radio sources from the literature, and we discuss avenues for further study of these and other sources using radio SED fitting as a starting point. The scalability and modularity of this framework make it an exciting tool for multiwavelength astronomers as next-generation telescopes begin several all-sky surveys. Accordingly, we make the code for RadioSED, which is written in Python, available on Github.

The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly at many wavelengths. Recently, young massive star clusters have been suggested to also efficiently produce high-energy cosmic rays, potentially beyond PeV energies. Here, we report the detection of very-high-energy $\gamma$-ray emission from the direction of R136 with the High Energy Stereoscopic System, achieved through a multicomponent, likelihood-based modeling of the data. This supports the hypothesis that R136 is indeed a very powerful cosmic-ray accelerator. Moreover, from the same analysis, we provide an updated measurement of the $\gamma$-ray emission from 30 Dor C, the only superbubble detected at TeV energies presently. The $\gamma$-ray luminosity above $0.5\,\mathrm{TeV}$ of both sources is $(2-3)\times 10^{35}\,\mathrm{erg}\,\mathrm{s}^{-1}$. This exceeds by more than a factor of 2 the luminosity of HESS J1646$-$458, which is associated with the most massive young star cluster in the Milky Way, Westerlund 1. Furthermore, the $\gamma$-ray emission from each source is extended with a significance of $>3\sigma$ and a Gaussian width of about $30\,\mathrm{pc}$. For 30 Dor C, a connection between the $\gamma$-ray emission and the nonthermal X-ray emission appears likely. Different interpretations of the $\gamma$-ray signal from R136 are discussed.

The brightest of all time (BOAT) GRB221009A show evidence for a narrow, evolving MeV emission line. Here, we show that this line can be explained as due to pair annihilation in the prompt emission region, and that its temporal evolution is naturally explained as the high-latitude emission (emission from higher angles from the line of sight) after prompt emission is over. We consider both the high and low optical depth for pair production regimes, and find acceptable solutions, with the GRB Lorentz factor $\Gamma \approx 600$ and the emission radius $r \gtrsim 10^{16.5}$~cm. We discuss the conditions for the appearance of such a line, and show that a unique combination of high luminosity and Lorentz factor that is in a fairly narrow range are required for the line detection. This explains why such an annihilation line is rarely observed in GRBs.

We compare the abundant prolate shaped galaxies reported beyond z$>$3 in deep JWST surveys, with the predicted {\it stellar} appearance of young galaxies in detailed hydro-simulations of three main dark matter contenders: Cold (CDM), Wave/Fuzzy ($\psi$DM) and Warm Dark Matter (WDM). We find the observed galaxy images closely resemble the elongated stellar appearance of young galaxies predicted for both $\psi$DM and WDM, during the first $\simeq$ 500Myr while material steadily accretes from long, smooth filaments. The dark mater halos of WDM and $\psi$DM also have pronounced, prolate elongation similar to the stars, indicating a shared, highly triaxial equilibrium. This is unlike CDM where the early stellar morphology is mainly spheroidal formed from fragmented filaments with frequent merging, resulting in modest triaxiality. Quantitatively, the excess of prolate galaxies observed by JWST matches well WDM and $\psi$DM for particle masses of 1.4KeV and $2.5\times 10^{-22}$ eV respectively. For CDM, several visible subhalos are typically predicted to orbit within the virial radius of each galaxy from subhalo accretion, whereas merging is initially rare for WDM and $\psi$DM. We also verify with our simulations that $\psi$DM may be distinguished from WDM by the form of the core, which is predicted to be smooth and centered for WDM, but is a dense soliton for $\psi$DM traced by stars and measurably offset from the galaxy center by random wave perturbations in the simulations. We emphasise that long smooth filaments absent of galaxies may prove detectable with JWST, traced by stars and gas with comoving lengths of 150kpc predicted at z$\simeq$10, depending on the particle mass of $\psi$DM or WDM.

In 2013, the IceCube Collaboration reported the first observation of an astrophysical neutrino flux, with energies extending up to the PeV-scale. Over the last decade, this flux has been characterized by measurements in multiple detection channels that are complementary with respect to the sensitive energy range, flavor composition, sky coverage, and backgrounds. The origin of these neutrinos remains largely unknown. However, evidence has been found for neutrino emission from the directions of the blazar TXS 0506+056, Seyfert galaxy NGC 1068. and the Galactic Plane. IceCube also has an active program of indirect dark matter searches with competitive constraints on dark matter models. In this talk, we will present recent results of the IceCube experiment, highlighting the latest diffuse flux measurements, point source searches, and dark matter analyses.

Primordial black holes (PBHs) with log-normal mass spectrum with masses up to $\sim 10^4-10^5 M_\odot$ can be created after QCD phase transition in the early Universe at $z\sim 10^{12}$ by the modified Affleck-Dine baryogenesis. Using a model binary PBH formation, the expected detection rate of such binary intermediate-mass PBHs by the TianQin space laser interferometer is calculated to be from a few to hundreds events per year for the assumed parameters of the PBH log-normal mass spectrum and abundance consistent with LIGO-Virgo-KAGRA results. Distinctive features of such primordial IMBH mergings are vanishingly small effective spins, possible high redshifts $z>20$ and lack of association with gas-rich regions or galaxies.

We have carried out spatially resolved thermal/nonthermal separation on two edge-on galaxies, NGC~3044 and NGC~5775, using only radio data. Narrow-band imaging within a frequency band that is almost contiguous from 1.25 to 7.02 GHz (L-band, S-band and C-band) has allowed us to fit spectra and construct thermal, nonthermal, and nonthermal spectral index maps. This method does not require any ancillary H$\alpha$ and infrared data, or reliance on dust corrections that are challenging in edge-on galaxies. For NGC~3044, at 15 arcsec resolution, we find a median thermal fraction of $\sim\, 13$\% with an estimated uncertainty in this fraction of $\sim\, 50$\% at 4.13 GHz. This compares well with the H$\alpha$ mixture method results. We uncovered evidence for a vertical outflow feature reaching at least $z\,\sim\,3.5$ kpc in projection above the plane, reminiscent of M82's starburst wind. For the higher SFR galaxy, NGC~5775 at 12 arcsec resolution, we find a median thermal fraction of 44\% at 4.13 GHz with an estimated error on this fraction of 17\%. Both galaxies show a change of slope (flattening) in L-band. These results suggest that a radio-only method for separating thermal from nonthermal emission is not only feasible, but able to reveal new features that might otherwise be obscured in edge-on disks.

Flares, sometimes accompanied by coronal mass ejections (CMEs), are the result of sudden changes in the magnetic field of stars with high energy release through magnetic reconnection, which can be observed across a wide range of the electromagnetic spectrum from radio waves to the optical range to X-rays. In our observational review, we attempt to collect some fundamental new results, which can largely be linked to the Big data era that has arrived due to the expansion of space photometric observations of the last two decades. We list the different types of stars showing flare activity, their observation strategies, and discuss how their main stellar properties relate to the characteristics of the flares (or even CMEs) they emit. Our goal is to focus, without claiming to be complete, on those results that may in one way or another challenge the "standard" flare model based on the solar paradigm.

We analyze the frequencies of three known roAp stars, TIC 96315731, TIC 72392575, and TIC 318007796, using the light curves from the Transiting Exoplanet Survey Satellite (TESS). For TIC 96315731, the rotational and pulsational frequencies are $0.1498360\,\mathrm{d}^{-1}$ and $165.2609\,\mathrm{d}^{-1}$, respectively. In the case of TIC 72392575, the rotational frequency is $0.25551\,\mathrm{d}^{-1}$. We detect a quintuplet of pulsation frequencies with a center frequency of $135.9233\,\mathrm{d}^{-1}$, along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation frequency. These two signals may correspond to the frequencies of a dipole mode. In TIC 318007796, the rotational and pulsational frequencies are $0.2475021\,\mathrm{d}^{-1}$, $192.73995\,\mathrm{d}^{-1}$, and $196.33065\,\mathrm{d}^{-1}$, respectively. Based on the oblique pulsator model, we calculate the rotation inclination $\left( i \right)$ and magnetic obliquity angle $\left( \beta \right)$ for the stars, which provides the geometry of the pulsation modes. Combining the phases of the frequency quintuplets, the pulsation amplitude and phase modulation curves, and the results of spherical harmonic decomposition, we conclude that the pulsation modes of frequency quintuplets in TIC 96315731, TIC 72392575, and TIC 318007796 correspond to distorted dipole mode, distorted quadrupole mode, and distorted dipole mode, respectively.

Understanding planet formation is important in the context of the origin of planetary systems in general and of the Solar System in particular, as well as to predict the likelihood of finding Jupiter, Neptune, and Earth analogues around other stars. We aim to precisely determine the radii and dynamical masses of transiting planets orbiting the young M star AU Mic using public photometric and spectroscopic datasets. We characterise the stellar activity and physical properties (radius, mass, density) of the transiting planets in the young AU Mic system through joint transit and radial velocity fits with Gaussian processes. We determine a radius of $R^{b}$= 4.79 +/- 0.29 R$_\oplus$, a mass of $M^{b}$= 9.0 +/- 2.7 M$_\oplus$, and a bulk density of $\rho^{b}$ = 0.49 +/- 0.16 g cm$^{-3}$ for the innermost transiting planet AU Mic b. For the second known transiting planet, AU Mic c, we infer a radius of $R^{c}$= 2.79 +/- 0.18 R$_\oplus$, a mass of $M^{c}$= 14.5 +/- 3.4 M$_\oplus$, and a bulk density of $\rho^{c}$ = 3.90 +/- 1.17 g cm$^{-3}$. According to theoretical models, AU Mic b may harbour an H2 envelope larger than 5\% by mass, with a fraction of rock and a fraction of water. AU Mic c could be made of rock and/or water and may have an H2 atmosphere comprising at most 5\% of its mass. AU Mic b has retained most of its atmosphere but might lose it over tens of millions of years due to the strong stellar radiation, while AU Mic c likely suffers much less photo-evaporation because it lies at a larger separation from its host. Using all the datasets in hand, we determine a 3$\sigma$ upper mass limit of $M^{[d]}\sin{i}$ = 8.6 M$_{\oplus}$ for the AU Mic 'd' TTV-candidate. In addition, we do not confirm the recently proposed existence of the planet candidate AU Mic 'e' with an orbital period of 33.4 days.

Aims. The space radiation environment conditions and the maximum expected coronal mass ejection (CME) speed are being assessed through the investigation of scaling laws between the peak proton flux and fluence of Solar Energetic Particle (SEP) events with the speed of the CMEs. Methods. We utilize a complete catalog of SEP events, covering the last ~25 years of CME observations (i.e. 1997 to 2017). We calculate the peak proton fluxes and integrated event fluences for those events reaching an integral energy of up to E> 100 MeV, covering the period of the last ~25 years of CME observations. For a sample of 38 strong SEP events, we first investigate the statistical relations between the recorded peak proton fluxes (IP) and fluences (FP) at a set of integral energies of E >10 MeV, E>30 MeV, E>60 MeV, and E>100 MeV versus the projected CME speed near the Sun (VCME) obtained by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph (SOHO/LASCO). Based on the inferred relations, we further calculate the integrated energy dependence of both IP and FP, assuming that they follow an inverse power-law with respect to energy. By making use of simple physical assumptions, we combine our derived scaling laws to estimate the upper limits for VCME, IP, and FP focusing on two cases of known extreme SEP events that occurred on February 23, 1956 (GLE05) and in AD774/775, respectively. Given physical constraints and assumptions, several options for the upper limit VCME, associated with these events, are investigated. Results. A scaling law relating IP and FP to the CME speed as V^{5}CME for CMEs ranging between ~3400-5400 km/s is consistent with values of FP inferred for the cosmogenic nuclide event of AD774/775. At the same time, the upper CME speed that the current Sun can provide possibly falls within an upper limit of VCME <= 5500 km/s.

This study concerns an inventory of the gravitational force and tidal field induced by filaments, walls, cluster nodes and voids on Megaparsec scales and how they assemble and shape the Cosmic Web. The study is based on a N$_{\rm Part}=512^3$ $\Lambda$CDM dark matter only N-body simulation in a (300$h^{-1}$~Mpc)$^3$ box at $z=0$. We invoke the density field NEXUS+ multiscale morphological procedure to assign the appropriate morphological feature to each location. We then determine the contribution by each of the cosmic web components to the local gravitational and tidal forces. We find that filaments are, by far, the dominant dynamical component in the interior of filaments, in the majority of underdense void regions and in all wall regions. The gravitational influence of cluster nodes is limited, and they are only dominant in their immediate vicinity. The force field induced by voids is marked by divergent outflowing patterns, yielding the impression of a segmented volume in which voids push matter towards their boundaries. Voids manifest themselves strongly in the tidal field as a cellular tapestry that is closely linked to the multiscale cosmic web. However, even within the interior of voids, the dynamical influence of the surrounding filaments is stronger than the outward push by voids. Therefore, the dynamics of voids cannot be understood without taking into account the influence of the environment. We conclude that filaments constitute the overpowering gravitational agent of the cosmic web, while voids are responsible for the cosmic web's spatial organisation and hence of its spatial connectivity.

Strong gravitational lensing magnifies the light from a background source, allowing us to study these sources in detail. Here, we study the spectra of a $z = 1.95$ lensed Type Ia supernova SN~Encore for its brightest Image A, taken 39 days apart. We infer the spectral age with template matching using the supernova identification (SNID) software and find the spectra to be at 29.0 $\pm 5.0$ and 37.4 $\pm 2.8$ rest-frame days post maximum respectively, consistent with separation in the observer frame after accounting for time-dilation. Since SNe~Ia measure dark energy properties by providing relative distances between low- and high-$z$ SNe, it is important to test for evolution of spectroscopic properties. Comparing the spectra to composite low-$z$ SN~Ia spectra, we find strong evidence for similarity between the local sample of SN~Encore. The line velocities of common SN~Ia spectral lines, Si II 6355 and Ca II NIR triplet are consistent with the distribution for the low-$z$ sample as well as other lensed SNe~Ia, e.g. iPTF16geu ($z = 0.409$) and SN~H0pe ($z = 1.78$). The consistency in SN~Ia spectra across cosmic time demonstrates the utility of using SNe~Ia in the very high-$z$ universe for dark energy inference. We also find that the spectra of SN~Encore match the predictions for explosion models very well. With future large samples of lensed SNe~Ia, spectra at such late phases will be important to distinguish between different explosion scenarios.

Numerical simulations of relativistic plasmas have become more feasible, popular, and crucial for various astrophysical sources with the availability of computational resources. The necessity for high-accuracy particle dynamics is especially highlighted in pulsar modelling due to the extreme associated electromagnetic fields and particle Lorentz factors. Including the radiation-reaction force in the particle dynamics adds even more complexity to the problem, but is crucial for such extreme astrophysical sources. We have also realised the need for such modelling concerning magnetic mirroring and particle injection models proposed for AR Sco, the first white dwarf pulsar. This paper demonstrates the benefits of using higher-order explicit numerical integrators with adaptive time step methods to solve the full particle dynamics with radiation-reaction forces included. We show that for standard test scenarios, namely various combinations of uniform $E$- and $B$-fields and a static dipole $B$-field, the schemes we use are equivalent to and in extreme field cases outperform standard symplectic integrators in accuracy. We show that the higher-order schemes have massive computational time improvements due to the adaptive time steps we implement, especially in non-uniform field scenarios and included radiation reaction where the particle gyro-radius rapidly changes. When balancing accuracy and computational time, we identified the adaptive Dormand-Prince eighth-order scheme to be ideal for our use cases. The schemes we use maintain accuracy and stability in describing the particle dynamics and we indicate how a charged particle enters radiation-reaction equilibrium and conforms to the analytic Aristotelian Electrodynamics expectations.

Understanding the nature and identity of dark matter is a key goal in the physics community. In the case that TeV-scale dark matter particles decay or annihilate into standard model particles, very-high-energy (VHE) gamma rays (greater than 100 GeV) will be present in the final state. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an imaging atmospheric Cherenkov telescope array that can indirectly detect VHE gamma rays in an energy range of 100 GeV to > 30 TeV. Dwarf spheroidal galaxies (dSphs) are ideal candidates in the search for dark matter due to their high dark matter content, high mass-to-light ratios, and their low gamma-ray fluxes from astrophysical processes. This study uses a legacy data set of 638 hours collected on 17 dSphs, built over 11 years with an observing strategy optimized according to the dark matter content of the targets. The study addresses a broad dark matter particle mass range, extending from 200 GeV to 30 PeV. In the absence of a detection, we set the upper limits on the dark matter velocity-weighted annihilation cross section.

*** Context: The halos of low-mass galaxies may allow us to constrain the nature of dark matter (DM), but the kinematic measurements to diagnose the required properties are technically extremely challenging. However, the photometry of these systems is doable. Aims. Using only stellar photometry, constrain key properties of the DM haloes in low-mass galaxies. *** Methods: Unphysical pairs of DM gravitational potentials and starlight distributions can be identified if the pair requires a distribution function f that is negative somewhere in the phase space. We use the classical Eddington inversion method (EIM) to compute f for a battery of DM gravitational potentials and around 100 observed low-mass galaxies with Mstar between 10**6 and 10**8 Msun. The battery includes NFW potentials (expected from cold DM) and potentials stemming from cored mass distributions (expected in many alternatives to cold DM). The method assumes spherical symmetry and isotropic velocity distribution and requires fitting the observed profiles with analytic functions, for which we use polytropes (with zero inner slope, a.k.a. core) and profiles with variable inner and outer slopes. The validity of all these assumptions is analyzed. *** Results: In general, the polytropes fit well the observed starlight profiles. If they were the correct fits (which could be the case) then all galaxies are inconsistent with NFW-like potentials. Alternatively, when the inner slope is allowed to vary for fitting, between 40% and 70% of the galaxies are consistent with cores in the stellar mass distribution and thus inconsistent with NFW-like potentials. *** Conclusions: Even though the stellar mass of the observed galaxies is still not low enough to constrain the nature of DM, this work shows the practical feasibility of the EIM technique to infer DM properties only from photometry.

Due to its inclined orbit and the complex geometry of the magnetic field of Neptune, Triton experiences a highly variable magnetic environment. As precipitation of magnetospheric electrons is thought to have a large impact on the Triton atmosphere, a better understanding of the interaction between its atmosphere and the magnetosphere of Neptune is important. We aim to couple a model of the Triton atmosphere with an electron transport model to compute the impact of a varying electron precipitation on the atmospheric composition. We coupled a recent photochemical model of the Triton atmosphere with the electron transport model TRANSPlanets. The inputs of this code were determined from Voyager 2 observations and previous studies. The main inputs were the electron precipitation flux, the orbital scaling factor, and the magnetic field strength. The electron-impact ionization and electron-impact dissociation rates computed by TRANSPlanets were then used in the photochemical model. We also analyzed the model uncertainties. The coupling of the two models enabled us to find an electron density profile, as well as N$_2$ and N number densities, that are consistent with the Voyager 2 observations. We found that photoionization and electron-impact ionization are of the same order, in contrast to the results of previous photochemical models. However, we emphasize that this result depends on the hypotheses we used to determine the input variables of TRANSPlanets. Our model would greatly benefit from new measurements of the magnetic environment of Triton, as well as of the electron fluxes in the Neptune magnetosphere.

Phase transitions in the early universe lead to a reduction in the equation of state of the primordial plasma. This exponentially enhances the formation rate of primordial black holes. However, this sensitivity to the equation of state is the same that primordial black hole abundances show to the primordial curvature power spectrum amplitude. In this paper, we investigate peaked power spectra and show the challenges associated with motivating populations of primordial black holes with standard model enhancements. The parametrisation of different power spectra plays an important role in this discussion. The allowed parameter space consistent with a large QCD phase transition impact on the primordial black hole abundance differs greatly. This is particularly evident for wider spectra.

The majority of stars in today's Universe reside within spheroids, which are bulges of spiral galaxies and elliptical galaxies. Their formation is still an unsolved problem. Infrared/submm-bright galaxies at high redshifts have long been suspected to be related to spheroids formation. Proving this connection has been hampered so far by heavy dust obscuration when focusing on their stellar emission or by methodologies and limited signal-to-noise ratios when looking at submm wavelengths. Here we show that spheroids are directly generated by star formation within the cores of highly luminous starburst galaxies in the distant Universe. This follows from the ALMA submillimeter surface brightness profiles which deviate significantly from those of exponential disks, and from the skewed-high axis-ratio distribution, both derived with a novel analysis technique. These galaxies are fully triaxial rather than flat disks: scale-height ratios are 0.5 on average and $>0.6$ for most spatially compact systems. These observations, supported by simulations, reveal a cosmologically relevant pathway for in-situ spheroid formation through starbursts likely preferentially triggered by interactions (and mergers) acting on galaxies fed by non co-planar gas accretion streams.

Previous simulations of cataclysmic variables studied either the quiescence, or the outburst state in multiple dimensions or they simulated complete outburst cycles in one dimension using simplified models for the gravitational torques. We self-consistently simulate complete outburst cycles of normal and superoutbursts in cataclysmic variable systems in two dimensions. We study the effect of different $\alpha$ viscosity parameters, mass transfer rates, and binary mass ratios on the disk luminosities, outburst occurrence rates, and superhumps. We simulate non-isothermal, viscous accretion disks in cataclysmic variable systems using a modified version of the FARGO code with an updated equation of state and a cooling function designed to reproduce s-curve behavior. Our simulations can model complete outburst cycles using the thermal tidal instability model. We find higher superhump amplitudes and stronger gravitational torques than previous studies, resulting in better agreement with observations.

Meridional flow is crucial in generating the solar poloidal magnetic field by facilitating the poleward transport of the field from the decayed Bipolar Magnetic Regions (BMRs). As the meridional circulation changes with the stellar rotation rate, the properties of stellar magnetic cycles are expected to be influenced by this flow. In this study, we explore the role of meridional flow in generating magnetic fields in Sun and sun-like stars using STABLE, Surface flux Transport And Babcock-Leighton, dynamo model. We find that a moderate meridional flow increases the polar field by efficiently driving the trailing polarity flux toward the pole, while a strong flow tends to transport both polarities of BMRs poleward, potentially reducing the polar field. Our findings are in perfect agreement with what one can expect from the surface flux transport model. Similarly, the toroidal field initially increases with moderate flow speeds and then decreases after a certain value. This trend is due to the competitive effects of shearing and diffusion. Furthermore, our study highlights the impact of meridional flow on the cycle strength and duration in stellar cycles. By including the meridional flow from a mean-field hydrodynamics model in STABLE, we show that the magnetic field strength initially increases with the stellar rotation rate and then declines in rapidly rotating stars, offering an explanation of the observed variation of stellar magnetic field with rotation rate.

Dark photon is a new gauge boson beyond the Standard Model as a kind of dark matter (DM) candidate. Dark photon dark matter (DPDM) interacts with electromagnetic fields via kinetic mixing, implicating an approach to give a constraint with extragalactic very high energy (VHE) sources. In this work, we attempt to constrain the kinetic mixing from the photon-dark photon scattering process in the host galaxy of blazar, the intergalactic medium and the Milky Way. The VHE photons from a blazar would pass through a dense DM spike around the supermassive black hole where the absorption from DPDM is dramatically enhanced. The kinetic mixing is constrained to be $\epsilon \sim 10^{-7}$ at a 95$\%$ confidence level with $m_{\rm D}\sim 0.03 - 1$ eV mass range from the observations of Markarian (Mrk) 421 and Mrk 501.

Current and future large-scale structure surveys aim to constrain cosmological parameters with unprecedented precision by analyzing vast amounts of data. This imposes a pressing need to develop fast and accurate methods for computing the matter power spectrum $P(k)$, or equivalently, the matter transfer function $T(k)$. In previous works, we introduced precise fitting formulas for these quantities within the standard cosmological model, including extensions such as the presence of massive neutrinos and modifications of gravity. However, these formulations overlooked a key characteristic imprinted in $P(k)$: the baryon acoustic oscillation signal. Here, we leverage our understanding of the well-known physics behind this oscillatory pattern to impose constraints on our genetic algorithm, a machine learning technique. By employing this ``physics-informed'' approach, we introduce an expression that accurately describes the matter transfer function with sub-percent mean accuracy. The high interpretability of the output allows for straightforward extensions of this formulation to other scenarios involving massive neutrinos and modifications of gravity. We anticipate that this formula will serve as a competitive fitting function for $P(k)$, meeting the accuracy requirements essential for cosmological analyses.

In this paper, we utilize recent observational data from Gamma-Ray Bursts (GRBs) and Pantheon+ Supernovae Ia (SNe Ia) sample to explore the interacting Dark Energy (IDE) model in a phenomenological scenario. Results from GRBs-only, SNe Ia and GRBs+SNe Ia indicate that the energy is transferred from dark energy to dark matter and the coincidence problem is alleviated. The value of H0 from GRBs+SNe Ia in the IDE scenario shows agreement with the SH0ES measurement. Considering the age estimate of the quasar APM 08279+5255 at z = 3.91, we find that the phenomenological IDE scenario can predict a cosmic age greater than that of the {\Lambda}CDM model, thus the cosmic age problem can be alleviated.

Detecting planet signatures in protoplanetary disks is fundamental to understanding how and where planets form. In this work, we report dust and gas observational hints of planet formation in the disk around 2MASS-J16120668-301027, as part of the ALMA Large Program ``AGE-PRO: ALMA survey of Gas Evolution in Protoplanetary disks''. The disk was imaged with the Atacama Large Millimeter/submillimeter Array (ALMA) at Band 6 (1.3 mm) in dust continuum emission and four molecular lines: $^{12}$CO(J=2-1), $^{13}$CO(J=2-1), C$^{18}$O(J=2-1), and H$_2$CO(J=3$_{(3,0)}$-2$_{(2,0)}$). Resolved observations of the dust continuum emission (angular resolution of $\sim 150$ mas, 20 au) show a ring-like structure with a peak at $0.57 ^{\prime \prime}$ (75 au), a deep gap with a minimum at 0.24$^{\prime \prime}$ (31 au), an inner disk, a bridge connecting the inner disk and the outer ring, along with a spiral arm structure, and a tentative detection (to $3\sigma$) of a compact emission at the center of the disk gap, with an estimated dust mass of $\sim 2.7-12.9$ Lunar masses. We also detected a kinematic kink (not coincident with any dust substructure) through several $^{12}$CO channel maps (angular resolution $\sim$ 200 mas, 30 au), located at a radius of $\sim 0.875^{\prime \prime}$ (115.6 au). After modeling the $^{12}$CO velocity rotation around the protostar, we identified a purple tentative rotating-like structure at the kink location with a geometry similar to that of the disk. We discuss potential explanations for the dust and gas substructures observed in the disk, and their potential connection to signatures of planet formation.

The contribution of the magnetic field to the formation of high-mass stars is poorly understood. We report the high-angular resolution ($\sim0.3^{\prime\prime}$, 870 au) map of the magnetic field projected on the plane of the sky (B$_\mathrm{POS}$) towards the high-mass star forming region G333.46$-$0.16 (G333), obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.2 mm as part of the Magnetic Fields in Massive Star-forming Regions (MagMaR) survey. The B$_\mathrm{POS}$ morphology found in this region is consistent with a canonical ``hourglass'' which suggest a dynamically important field. This region is fragmented into two protostars separated by $\sim1740$ au. Interestingly, by analysing H$^{13}$CO$^{+}$ ($J=3-2$) line emission, we find no velocity gradient over the extend of the continuum which is consistent with a strong field. We model the B$_\mathrm{POS}$, obtaining a marginally supercritical mass-to-flux ratio of 1.43, suggesting an initially strongly magnetized environment. Based on the Davis-Chandrasekhar-Fermi method, the magnetic field strength towards G333 is estimated to be 5.7 mG. The absence of strong rotation and outflows towards the central region of G333 suggests strong magnetic braking, consistent with a highly magnetized environment. Our study shows that despite being a strong regulator, the magnetic energy fails to prevent the process of fragmentation, as revealed by the formation of the two protostars in the central region.

We investigate how galaxy pairs are oriented in three dimensions within cosmic filaments using data from the EAGLE simulation. We identify filament spines using DisPerSE and isolate galaxies residing in filamentary environments. Employing a FoF algorithm, we delineate individual filaments and determine their axes by diagonalizing the moment of inertia tensor. The orientations of galaxy pairs relative to the axis of their host filament are analyzed. Our study covers diverse subsets of filaments identified through varying linking lengths, examining how galaxy pairs align with the filament axis across different spatial parameters such as pair separation and distance from the filament spine. We consistently observe a strong alignment pattern characterized by the probability distribution for the cosine of the orientation angle, which is nearly identical in each case. Furthermore, the study investigates the impact of redshift space distortions, confirming that the alignment signal persists in both real and redshift space. To validate our method, we employ Monte Carlo simulations with different theoretical probability distributions. Our results reaffirm previous findings with projected two-dimensional distributions and extend our understanding of how filaments impact the spatial organization and evolution of galaxies across cosmic scales.

Recent Baryon Acoustic Oscillation (BAO) measurements released by DESI, when combined with Cosmic Microwave Background (CMB) data from Planck and two different samples of Type Ia supernovae (Pantheon-Plus and DESY5) reveal a preference for Dynamical Dark Energy (DDE) characterized by a present-day quintessence-like equation of state that crossed into the phantom regime in the past. A core ansatz for this result is assuming a linear Chevallier-Polarski-Linder (CPL) parameterization $w(a) = w_0 + w_a (1-a)$ to describe the evolution of the DE equation of state (EoS). In this paper, we test if and to what extent this assumption impacts the results. To prevent broadening uncertainties in cosmological parameter inference and facilitate direct comparison with the baseline CPL case, we focus on 4 alternative well-known models that, just like CPL, consist of only two free parameters: the present-day DE EoS ($w_0$) and a parameter quantifying its dynamical evolution ($w_a$). We demonstrate that the preference for DDE remains robust regardless of the parameterization: $w_0$ consistently remains in the quintessence regime, while $w_a$ consistently indicates a preference for a dynamical evolution towards the phantom regime. This tendency is significantly strengthened by DESY5 SN measurements. By comparing the best-fit $\chi^2$ obtained within each DDE model, we notice that the linear CPL parameterization is not the best-fitting case. Among the models considered, the EoS proposed by Barboza and Alcaniz consistently leads to the most significant improvement.

We present the variations in far-ultraviolet (FUV) and H$\alpha$ star formation rates (SFR), SFR$_{UV}$ and SFR$_{H\alpha}$, respectively, at sub-kpc scales in 11 galaxies as part of the Deciphering the Interplay between the Interstellar Medium, Stars, and the Circumgalactic medium (DIISC) survey. Using archival GALEX FUV imagery and H$\alpha$+[NII] narrowband images obtained with the Vatican Advanced Technology Telescope, we detect a total of 1335 (FUV-selected) and 1474 (H$\alpha$-selected) regions of recent high-mass star formation, respectively. We find the H$\alpha$-to-FUV SFR ratios tend to be lower primarily for FUV-selected regions, where SFR$_{H\alpha}$ generally underestimates the SFR by an average factor of 2-3, for SFR $<$ 10$^{-4}$ M$_{\odot}$ yr$^{-1}$. In contrast, the SFRs are generally observed to be consistent for H$\alpha$-selected regions. This discrepancy arises from morphological differences between the two indicators. Extended FUV morphologies and larger areas covered by FUV-only regions, along with decreasing overlap between FUV clumps and compact HII regions with $R/R_{25}$ suggest that stochastic sampling of the initial mass function may be more pronounced in the outer regions of galaxies. Our observed H$\alpha$-to-FUV SFR ratios are also consistent with stochastic star formation model predictions. However, using larger apertures that include diffuse FUV emission results in an offset of 1 dex between SFR$_{H\alpha}$ and SFR$_{UV}$. This suggests that the observed low H$\alpha$-to-FUV SFR ratios in galaxies are likely caused by diffuse FUV emission, which can contribute $\sim$60-90\% to the total FUV flux.