Papers for Wednesday, Feb 07 2024

In this paper, we report the detection of amplitude modulation in a delta Scuti star HD118660. We found that the p-mode frequency at 24.3837 c/d varies periodically in amplitude with frequency 0.0558 c/d. However, all other modes are stable in both amplitude and phase which is clear evidence of non-conservation of visible pulsation mode energy. We constructed a two-frequency model by superimposing two sinusoids with frequencies n1 = 24.3837 c/d and n2 = 24.4420 c/d and corresponding phases f1 = 0:5211 rad and f2 = 0:9481 rad to mimic the observed variations of amplitude and phase with time. The plausible explanation of the amplitude modulation in HD118660 is due to beating of two unresolved closed frequencies n1 and n2.

The cold ($\sim 10^{4}\,{\rm K}$) component of the circumgalactic medium (CGM) accounts for a significant fraction of all galactic baryons. However, using current galaxy-scale simulations to determine the origin and evolution of cold CGM gas poses a significant challenge, since it is computationally infeasible to directly simulate a galactic halo alongside the sub-pc scales that are crucial for understanding the interactions between cold CGM gas and the surrounding ''hot'' medium. In this work, we introduce a new approach: the Cold Gas Subgrid Model (CGSM), which models unresolved cold gas as a second fluid in addition to the standard ''normal'' gas fluid. The CGSM tracks the total mass density and bulk momentum of unresolved cold gas, deriving the properties of its unresolved cloudlets from the resolved gas phase. The interactions between the subgrid cold fluid and the resolved fluid are modeled by prescriptions from high-resolution simulations of ''cloud crushing'' and thermal instability. Through a series of idealized tests, we demonstrate the CGSM's ability to overcome the resolution limitations of traditional hydrodynamics simulations, successfully capturing the correct cold gas mass, its spatial distribution, and the timescales for cloud destruction and growth. We discuss the implications of using this model in cosmological simulations to more accurately represent the microphysics that govern the galactic baryon cycle.

The physical processes by which gas is accreted onto galaxies, transformed into stars and then expelled from galaxies are of paramount importance to galaxy evolution studies. Observationally constraining each of these baryonic components in the same systems however, is challenging. Furthermore, simulations indicate that the stellar mass of galaxies is a key factor influencing CGM properties. Indeed, absorption lines detected against background quasars offer the most compelling way to study the cold gas in the circumgalactic medium (CGM). The MUSE-ALMA Haloes survey is composed of quasar fields covered with VLT/MUSE observations, comprising 32 \ion{H}{i} absorbers at 0.2 $<$ $z$ $<$ 1.4 and 79 associated galaxies, with available or upcoming molecular gas measurements from ALMA. We use a dedicated 40-orbit HST UVIS and IR WFC3 broad-band imaging campaign to characterise the stellar content of these galaxies. By fitting their spectral energy distribution, we establish they probe a wide range of stellar masses: 8.1 $<$ log($M_*$/M$_{\odot}$) $<$ 12.4. Given their star-formation rates, most of these objects lie on the main sequence of galaxies. We also confirm a previously reported anti-correlation between the stellar masses and CGM hydrogen column density N(\ion{H}{i}), indicating an evolutionary trend where higher mass galaxies are less likely to host large amounts of \ion{H}{i} gas in their immediate vicinity up to 120 kpc. Together with other studies from the MUSE-ALMA Haloes survey, these data provide stellar masses of absorber hosts, a key component of galaxy formation and evolution, and observational constraints on the relation between galaxies and their surrounding medium.

Main-belt asteroid (16) Psyche is the largest M-type asteroid, a class of object classically thought to be the metal cores of differentiated planetesimals and the parent bodies of the iron meteorites. de Kleer, Cambioni, and Shepard (2021, https://doi.org/10.3847/psj/ac01ec) presented new data from the Atacama Large Millimeter Array (ALMA), from which they derived a global best-fit thermal inertia and dielectric constant for Psyche, proxies for regolith particle size, porosity, and/or metal content, and observed thermal anomalies that could not be explained by surface albedo variations only. Motivated by this, here we fit a model to the same ALMA data set that allows dielectric constant and thermal inertia to vary across the surface. We find that Psyche has a heterogeneous surface in both dielectric constant and thermal inertia but, intriguingly, we do not observe a direct correlation between these two properties over the surface. We explain the heterogeneity in dielectric constant as being due to variations in the relative abundance of metal and silicates. Furthermore, we observe that the lowlands of a large depression in Psyche's shape have distinctly lower thermal inertia than the surrounding highlands. We propose that the latter could be explained by a thin mantle of fine regolith, fractured bedrock, and/or implanted silicate-rich materials covering an otherwise metal-rich surface. All these scenarios are indicative of a collisionally evolved world.

A new model is proposed in which typical galaxies form most of their stellar mass in a phase with an intrinsically red stellar population. In the standard picture, galaxies with intrinsically red stellar populations are believed to have old stellar populations, so that only galaxies with blue stellar populations have significant star formation, and subsequent changes to the stellar population come from predominantly from aging and merging populations which have already formed. However, several observational puzzles have developed which are difficult to reconcile with this standard scenario. The most massive blue star-forming galaxies, presumed to be at the end of their stellar mass growth, are $\sim 1$ dex less massive, have a $\sim 1$ dex lower $M_*/M_{BH}$ ratio, and have a bottom-lighter IMF than local quiescent galaxies. Here, a new solution is proposed: at low temperature and high metallicity, galaxies can continue to form stars efficiently without being able to form O and B stars. These red star-forming galaxies would have many of the same properties of the population currently described as post-starburst galaxies, allowing a new interpretation of their origin. Finally, additional falsifiable observational predictions of this model are also discussed.

We study the impact of the assumption of a non-flat fiducial cosmology on the measurement, analysis and interpretation of BAO distance variables, along and across the line-of-sight. The assumption about cosmology enters in the choice of the base template, as well as on the transformation of tracer's redshifts into distances (the catalog cosmology): here we focus on the curvature assumption, separately and jointly, on both. We employ BOSS and eBOSS publicly available data and show that for the statistical precision of this data set, distance measures and thus cosmological inference are robust to assumptions about curvature both of the template and the catalog. Thus the usual assumptions of flat fiducial cosmologies (but also assumptions of non-flat cosmologies) do not produce any detectable systematic effects. For forthcoming large-volume surveys, however, small but appreciable residual systematic shifts can be generated which may require some care. These are mostly driven by the choice of catalog cosmology if it is significantly different from true cosmology. In particular, the catalog (and template) cosmology should be chosen, possibly iteratively, in such a way that the recovered BAO scaling variables are sufficiently close to unity. At this level of precision, however, other previously overlooked effects become relevant, such as a mismatch between the sound horizon as seen in the BAO and the actual sound horizon in the early Universe. If unaccounted for, such effect may be misinterpreted as cosmological and thus bias the curvature (and cosmology) constraints.

The chemical enrichment of the early Universe is a crucial element in the formation and evolution of galaxies, and Population III (PopIII) stars must play a vital role in this process. In this study, we examine metal enrichment from massive stars in the early Universe's embryonic galaxies. Using radiation hydrodynamic simulations and stellar evolution modelling, we calculated the expected metal yield from these stars. Specifically, we applied accretion rates from a previous radiation-hydrodynamic simulation to inform our stellar evolution modelling, executed with the Geneva code, across 11 selected datasets, with final stellar masses between 500 and 9000 Msol. Our results demonstrate that the first generation of Pop III stars within a mass range of 2000 to 9000 Msol result in N/O, C/O and O/H ratios compatible with the values observed in very high-z galaxies GN-z11 and CEERS 1019. The ejecta of these Pop III stars are predominantly composed of He, H, and N. Our Pop III chemical enrichment model of the halo can accurately reproduce the observed N/O and C/O ratios, and, by incorporating a hundred times more zero-metallicity interstellar material with the stellar ejecta, it accurately attains the observed O/H ratio. Thus, a sub-population of extremely massive PopIII stars, with masses surpassing approximately 2000 Msol, effectively reproduces the CNO elemental abundances observed in high-z JWST galaxies to date.

Placed slightly out of dynamical equilibrium, an isolated stellar system quickly returns towards a steady virialized state. We study this process of collisionless relaxation using the matrix method of linear response theory. We show that the full phase space distribution of the final virialized state can be recovered directly from the disequilibrium initial conditions, without the need to compute the time evolution of the system. This shortcut allows us to determine the final virialized configuration with minimal computational effort. Complementing this result, we develop tools to model the system's full time evolution in the linear approximation. In particular, we show that moments of the velocity distribution can be efficiently computed using a generalized moment matrix. We apply our linear methods to study the relaxation of energy-truncated Hernquist spheres, mimicking the tidal stripping of a cuspy dark matter subhalo. Comparison of our linear predictions against controlled, isolated $N$-body simulations shows agreement at per cent level for the parts of the system where a linear response to the perturbation is expected. We find that relaxation generates a tangential velocity anisotropy in the intermediate regions, despite the initial disequilibrium state having isotropic kinematics. We further confirm that relaxation is responsible for depleting the amplitude of the density cusp, without affecting its asymptotic slope. Finally, we compare the linear theory against $N$-body simulation of tidal stripping on a radial orbit, confirming that the theory still accurately predicts density and velocity dispersion profiles for most of the system.

In anticipation of the Euclid Wide and Deep Surveys, we present optical emission-line predictions at intermediate redshifts from 0.4 to 2.5. Our approach combines a mock light cone from the GAEA semi-analytic model to self-consistently model nebular emission from HII regions, narrow-line regions of active galactic nuclei (AGN), and evolved stellar populations. Our analysis focuses on seven optical emission lines: H$\alpha$, H$\beta$, [SII]$\lambda\lambda 6717, 6731$, [NII]$\lambda 6584$, [OI]$\lambda 6300$, [OIII]$\lambda 5007$, and [OII]$\lambda\lambda 3727, 3729$. We find that Euclid will predominantly observe massive, star-forming, and metal-rich line-emitters. Interstellar dust, modelled using a Calzetti law with mass-dependent scaling, may decrease observable percentages by a further 20-30% with respect to our underlying emission-line populations from GAEA. We predict Euclid to observe around 30-70% of H$\alpha$-, [NII]-, [SII]-, and [OIII]-emitting galaxies at redshift below 1 and under 10% at higher redshift. Observability of H$\beta$-, [OII]-, and [OI]- emission is limited to below 5%. For the Euclid-observable sample, we find that BPT diagrams can effectively distinguish between different galaxy types up to around redshift 1.8, attributed to the bias toward metal-rich systems. Moreover, we show that the relationships of H$\alpha$ and [OIII]+H$\beta$ to the star-formation rate, and the [OIII]-AGN luminosity relation, exhibit minimal changes with increasing redshift. Based on line ratios [NII]/H$\alpha$, [NII]/[OII], and [NII]/[SII], we further propose novel z-invariant tracers for the black hole accretion rate-to-star formation rate ratio. Lastly, we find that commonly used metallicity estimators display gradual shifts in normalisations with increasing redshift, while maintaining the overall shape of local calibrations. This is in tentative agreement with recent JWST data.

Determination of solar magnetic fields with a spatial resolution set by the diffraction limit of a telescope is difficult because the time required to measure the Stokes vector with sufficient signal-to-noise is long compared to the solar evolution timescale. This difficulty gets worse with increasing telescope size as the photon flux per diffraction-limited resolution element remains constant but the evolution timescale decreases linearly with the diffraction-limited resolution. We aim to improve magnetic field reconstruction at the diffraction limit without averaging the observations in time or space, and without applying noise filtering. The magnetic field vector tends to evolve slower than the temperature, velocity and microturbulence. We exploit this by adding temporal regularisation terms for the magnetic field to the linear least-squares fitting used in the weak-field approximation, as well as to the Levenberg-Marquardt algorithm used in inversions. The other model parameters are allowed to change in time without constraints. We infer the chromospheric magnetic field from Ca II 854.2 nm observations using the weak field approximation and the photospheric magnetic field from Fe I 617.3 nm observations using Milne-Eddington inversions, both with and without temporal regularisation. Temporal regularisation reduce the noise in the reconstructed maps of the magnetic field and provides a better coherency in time in both the weak-field approximation and Milne-Eddington inversions. Temporal regularisation markedly improves magnetic field determination from spatially and temporally resolved observations.

A fundamental question in the study of planetary system demographics is: how common is the solar system architecture? The primary importance of this question lies in the potential of planetary systems to create habitable environments, and dissecting the various components of solar system evolution that contributed to a sustainable temperate surface for Earth. One important factor in that respect is volatile delivery to the inner system and the dependence on giant planets beyond the snow line as scattering agents, particularly as such cold giant planets are relatively rare. Here, we provide an investigation of the eccentricity distribution for giant planet populations both interior and exterior to their system snow lines. We show that the median eccentricity for cold giants is 0.23, compared with a far more circular orbital regime for inner planets. We further present the results of a dynamical simulation that explores the particle scattering potential for a Jupiter analog in comparison with a Jupiter whose eccentricity matches that of the median cold giant eccentricity. These simulations demonstrate that the capacity for such an eccentric cold giant system to scatter volatiles interior to the snow line is significantly increased compared with the Jupiter analog case, resulting in a far greater volume of Earth-crossing volatiles. Thus, many of the known systems with cold giant planets may harbor water worlds interior to the snow line.

Tidal disruption events (TDEs) are multi-messenger transients in which a star is tidally destroyed by a supermassive black hole at the center of galaxies. The Rubin Observatory Legacy Survey of Space and Time (LSST) is anticipated to annually detect hundreds to thousands of TDEs, such that the first gravitationally lensed TDE may be observed in the coming years. Using Monte-Carlo simulations, we quantify the rate of both unlensed and lensed TDEs as a function of limiting magnitudes in four different optical bands ($u$, $g$, $r$, and $i$) for a range of TDE temperatures that match observations. Dependent on the temperature and luminosity model, we find that $g$ and $r$ bands are the most promising bands with unlensed TDE detections that can be as high as ${\sim}10^{4}$ annually. By populating a cosmic volume with realistic distributions of TDEs and galaxies that can act as gravitational lenses, we estimate that a few lensed TDEs (depending on the TDE luminosity model) can be detected annually in $g$ or $r$ bands in the LSST survey, with TDE redshifts in the range of ${\sim}0.5$ to ${\sim}2$. The ratio of lensed to unlensed detections indicates that we may detect ${\sim}1$ lensed event for every $10^{4}$ unlensed events, which is independent of the luminosity model. The number of lensed TDEs decreases as a function of the image separations and time delays, and most of the lensed TDE systems are expected to have image separations below ${\sim}3"$ and time delays within ${\sim}30$ days. At fainter limiting magnitudes, the $i$ band becomes notably more successful. These results suggest that strongly lensed TDEs are likely to be observed within the coming years and such detections will enable us to study the demographics of black holes at higher redshifts through the lensing magnifications.

Burst with memory events are potential transient gravitational wave sources for the maturing pulsar timing array (PTA) efforts. We provide a computationally efficient prescription to model pulsar timing residuals induced by supermassive black hole pairs in general relativistic hyperbolic trajectories employing a Keplerian-type parametric solution. Injection studies have been pursued on the resulting bursts with linear GW memory (LGWM) events with simulated datasets to test the performance of our pipeline, followed by its application to the publicly available NANOGrav 12.5-year (NG12.5) dataset. Given the absence of any evidence of LGWM events within the real NG12.5 dataset, we impose 95\% upper limits on the PTA signal amplitude as a function of the sky location of the source and certain characteristic frequency ($n$) of the signal. The upper limits are computed using a signal model that takes into account the presence of intrinsic timing noise specific to each pulsar, as well as a common, spatially uncorrelated red noise, alongside the LGWM signal. Our investigations reveal that the $95\%$ upper limits on LGWM amplitude, marginalized over all other parameters, is 3.48 $\pm 0.51 \ \mu$s for $n>3.16$ nHz. This effort should be relevant for constraining both burst and memory events in the upcoming International Pulsar Timing Array data releases.

Over the past few decades, many applications of physics-based simulations and data-driven techniques (including machine learning and deep learning) have emerged to analyze and predict solar flares. These approaches are pivotal in understanding the dynamics of solar flares, primarily aiming to forecast these events and minimize potential risks they may pose to Earth. Although current methods have made significant progress, there are still limitations to these data-driven approaches. One prominent drawback is the lack of consideration for the temporal evolution characteristics in the active regions from which these flares originate. This oversight hinders the ability of these methods to grasp the relationships between high-dimensional active region features, thereby limiting their usability in operations. This study centers on the development of interpretable classifiers for multivariate time series and the demonstration of a novel feature ranking method with sliding window-based sub-interval ranking. The primary contribution of our work is to bridge the gap between complex, less understandable black-box models used for high-dimensional data and the exploration of relevant sub-intervals from multivariate time series, specifically in the context of solar flare forecasting. Our findings demonstrate that our sliding-window time series forest classifier performs effectively in solar flare prediction (with a True Skill Statistic of over 85\%) while also pinpointing the most crucial features and sub-intervals for a given learning task.

Breathing pulses are mixing episodes that could develop during the core-helium burning phase of low- and intermediate-mass stars. The occurrence of breathing pulses is expected to bear consequences on the formation and evolution of white dwarfs, particularly on the core chemical structure, which can be probed by asteroseismology. We aim to explore the consequences of breathing pulses on the chemical profiles and pulsational properties of variable white-dwarf stars with hydrogen-rich envelopes, known as ZZ Ceti stars. We compute stellar models with masses of $1.0 M_{\odot}$ and $2.5 M_{\odot}$ in the zero-age main sequence, and evolve them through the core-helium burning phase to the thermal pulses on the asymptotic giant branch, and finally to advanced stages of white-dwarf cooling. We compare the chemical structure of the core of white dwarfs whose progenitors have experienced breathing pulses during the core-helium burning phase with the case in which breathing pulses have not occurred. We find that, when breathing pulses occur, the white-dwarf cores are larger and the central abundances of oxygen are higher than for the case in which the breathing pulses are suppressed, in line with previous studies. However, the occurrence of breathing pulses is not sufficient to explain the large cores and the excessive oxygen abundances that characterize recently derived asteroseismological models of pulsating white dwarfs. We find absolute differences of up to $\sim 30$ seconds when we compare pulsation periods of white dwarfs coming from progenitors that have experienced breathing pulses with the case in which the progenitors have not suffered breathing pulses.

We present NIRCam and NIRISS modules for DOLPHOT, a widely-used crowded field stellar photometry package. We describe details of the modules including pixel masking, astrometric alignment, star finding, photometry, catalog creation, and artificial star tests (ASTs). We tested these modules using NIRCam and NIRISS images of M92 (a Milky Way globular cluster), Draco II (an ultra-faint dwarf galaxy), and WLM (a star-forming dwarf galaxy). DOLPHOT's photometry is highly precise and the color-magnitude diagrams are deeper and have better definition than anticipated during original program design in 2017. The primary systematic uncertainties in DOLPHOT's photometry arise from mismatches in the model and observed point spread functions (PSFs) and aperture corrections, each contributing $\lesssim0.01$ mag to the photometric error budget. Version 1.2 of WebbPSF models, which include charge diffusion and interpixel capacitance effects, significantly reduced PSF-related uncertainties. We also observed minor ($\lesssim0.05$ mag) chip-to-chip variations in NIRCam's zero points, which will be addressed by the JWST flux calibration program. Globular cluster observations are crucial for photometric calibration. Temporal variations in the photometry are generally $\lesssim0.01$ mag, although rare large misalignment events can introduce errors up to 0.08 mag. We provide recommended DOLPHOT parameters, guidelines for photometric reduction, and advice for improved observing strategies. Our ERS DOLPHOT data products are available on MAST, complemented by comprehensive online documentation and tutorials for using DOLPHOT with JWST imaging data.

The presence of a spectral softening, occurring at 3 PeV energies, seen in the local cosmic-ray energy spectrum provides an evidence that our Galaxy hosts astrophysical objects, known as hadronic PeVatrons, that are capable of accelerating hadrons to PeV energies and above. Recent results from ground-based particle detector array experiments have provided conclusive evidence that these facilities are essential to explore the ultra-high-energy (UHE, E>100 TeV) domain and pinpoint the location of PeVatrons in the Galaxy. The Southern Wide-field Gamma-ray Observatory (SWGO) is proposed next-generation ground-based extensive air shower observatory, which holds great scientific potential for UHE observations. In this study, we investigate the expected potential of SWGO to search for hadronic PeVatrons, based on the publicly available preliminary SWGO straw-man IRFs. It can be shown that the SWGO detection of gamma-ray spectral cutoffs between 30 TeV and 100 TeV is possible for faint gamma-ray sources of 5~mCrab given that the spectral index is hard ($\Gamma$<2.0), while spectral cutoffs from softer sources with $\Gamma$=2.3 can be detected for sources brighter than 11-12 mCrab. The reconstructed SWGO PeVatron detection maps demonstrate that the future SWGO experiment can probe large parts of the investigated PeVatron parameter space, providing a robust detection and/or rejection of presence of spectral signatures associated with hadronic PeVatrons. A dedicated study on the promising PeVatron candidates, the Galactic Center region, Westerlund~1, HESSJ1702-420 and HESSJ1641-463, shows that the SWGO will have a great potential to confirm or exclude PeVatron nature of these candidate sources at a robust significance level after 5-years of observation. In addition, it is shown that controlling systematic errors will be necessary to reach full potential of the SWGO experiment for PeVatron searches.

The coarse-grained propagation of Galactic cosmic rays (CRs) is traditionally constrained by phenomenological models of Milky Way CR propagation fit to a variety of direct and indirect observables; however, constraining the fine-grained transport of CRs along individual magnetic field lines -- for instance, diffusive vs streaming transport models -- is an unsolved challenge. Leveraging a recent training set of magnetohydrodynamic turbulent box simulations, with CRs spanning a range of transport parameters, we use convolutional neural networks (CNNs) trained solely on gas density maps to classify CR transport regimes. We find that even relatively simple CNNs can quite effectively classify density slices to corresponding CR transport parameters, distinguishing between streaming and diffusive transport, as well as magnitude of diffusivity, with class accuracies between $92\%$ and $99\%$. As we show, the transport-dependent imprints that CRs leave on the gas are not all tied to the resulting density power spectra: classification accuracies are still high even when image spectra are flattened ($85\%$ to $98\%$ accuracy), highlighting CR transport-dependent changes to turbulent phase information. We interpret our results with saliency maps and image modifications, and we discuss physical insights and future applications.

The availability of large, public, multi-modal astronomical datasets presents an opportunity to execute novel research that straddles the line between science of AI and science of astronomy. Photometric redshift estimation is a well-established subfield of astronomy. Prior works show that computer vision models typically outperform catalog-based models, but these models face additional complexities when incorporating images from more than one instrument or sensor. In this report, we detail our progress creating Mantis Shrimp, a multi-survey computer vision model for photometric redshift estimation that fuses ultra-violet (GALEX), optical (PanSTARRS), and infrared (UnWISE) imagery. We use deep learning interpretability diagnostics to measure how the model leverages information from the different inputs. We reason about the behavior of the CNNs from the interpretability metrics, specifically framing the result in terms of physically-grounded knowledge of galaxy properties.

In this paper we review the possible mechanisms for the production of primordial black holes (PBHs) during a slow-reheating period {in which the energy transfer of the inflaton field to standard model particles becomes effective at slow temperatures}, offering a comprehensive examination of the theoretical foundations and conditions required for each of formation channel. In particular, we focus on post-inflationary scenarios where there are no self-resonances and the reheating epoch can be described {by the inflaton evolving in} a quadratic-like potential. In the hydrodynamical interpretation of this field during the slow-reheating epoch, the gravitational collapse of primordial fluctuations is subject to conditions on their sphericity, limits on their spin, as well as a maximum velocity dispersion. We show how to account for all conditions and show that PBHs form with different masses depending on the collapse mechanism. Finally we show, through an example, how PBH production serves to probe both the physics after primordial inflation, as well as the primordial powerspectrum at the smallest scales.

Magnetic reconnection is understood to be the main physical process that facilitates the transformation of magnetic energy into heat, motion, and particle acceleration during solar eruptions. Yet, observational constraints on reconnection region properties and dynamics are limited due to lack of high-cadence and high-spatial-resolution observations. By studying the evolution and morphology of post-reconnected field-lines footpoints, or flare ribbons and vector photospheric magnetic field, we estimate the magnetic reconnection flux and its rate of change with time to study the flare reconnection process and dynamics of the current sheet above. We compare high-resolution imaging data to study the evolution of the fine structure in flare ribbons as ribbons spread away from the polarity inversion line. Using data from two illustrative events (one M- and X-class flare), we explore the relationship between the ribbon-front fine structure and the temporal development of bursts in the reconnection region. Additionally, we use the RibbonDB database to perform statistical analysis of 73 (C- to X-class) flares and identify QPP's properties using the Wavelet Transform. Our main finding is the discovery of quasi-periodic pulsations (QPP) signatures in the derived magnetic reconnection rates in both example events and the large flare sample. We find that the oscillations' periods range from one to four minutes. Furthermore, we find nearly co-temporal bursts in Hard X-ray (HXR) emission profiles. We discuss how dynamical processes in the current sheet involving plasmoids can explain the nearly-co-temporal signatures of quasi periodicity in the reconnection rates and HXR emission.

The determination of planetary densities from the masses derived with the radial velocity (RV) and transit-timing variation (TTV) methods reveals discrepancies. Specifically, planets detected through RV exhibit higher densities than those detected through TTV, even though their radii are similar. We explored the possibility that the discrepant mass/densities in the TTV and RV populations might be linked to the properties of the environments in which these planets are formed. For the largest currently available sample of FGK-type stars hosting low-mass TTV and RV planets, we determined the host star abundances. Then, by employing a simple stoichiometric model, we used these abundances to estimate the iron-to-silicate mass fraction ($f_{iron}$) and the water-mass fraction ($w_{f}$) of the protoplanetary disks. We also calculated the kinematic properties of the host stars. We observed an indication that the hosts of TTV planets have slightly higher $f_{iron}$ and lower $w_{f}$ values than their RV counterparts. This suggests that TTV planets (without considering their atmospheres) are denser than RV planets on average, which implies that larger atmospheres on TTV planets are required to account for their overall lower densities. However, we also note differences in the properties of the planets, such as their orbital periods, and variations in the quality of the spectroscopic data, which may have an impact on these results. Exploring the TTV-RV mass and/or density discrepancy through a chemical analysis of the host star holds promise for future research, particularly with larger sample sizes and higher-quality data. Meanwhile, the provided detailed host star abundances can be employed to study the composition of the planets within the current sample, thereby contributing to a better understanding of the aforementioned discrepancy.

We present the discovery of a peculiar dwarf nova KSP-OT-201712a using high-cadence, multi-color observations made with the Korea Microlensing Telescope Network. KSP-OT-201712a exhibits a rare presence of outbursts during standstills as well as strong H${\alpha}$ emission for a dwarf nova below the period minimum with an orbital period of 58.75 $\pm$ 0.02 minutes. The outburst cycles are ~ 6.6 days within standstills but increase to ~ 15 days outside of them. Both B-V and V-I colors become bluer and redder as the outburst luminosities increase and decrease, respectively, for the outburst within standstill, while they evolve in the opposite directions outside of the standstills. The presence of strong double-peaked H${\alpha}$ and weak He I emission lines with He/H flux ratio of 0.27, together with absorption lines of Mg b and Na D in the source, leads to the estimation Teff ~ 4570 $\pm$ 40 K, [Fe/H] ~ 0.06 $\pm$ 0.15 dex, and log g ~ 4.5 $\pm$ 0.1 for its secondary. KSP-OT-201712a is the second He-deficient dwarf nova below the period minimum, while the temperature of the secondary is measured for the first time in such objects. We identify it to be an ER UMa type dwarf nova suggesting that the evolution of dwarf novae across the period minimum is accompanied by large mass transfers. The high temperature of the secondary indicates that the system started its mass transfer when the secondary was about 93$\%$ of its main sequence age. The system will evolve to a helium cataclysmic variable or to AM CVn once its hydrogen envelope is exhausted before it explodes as a Type Ia supernova.

Two heavy elements essential to human biology are thought to have been produced by the astrophysical $r$-process, which occurs in neutron-rich environments: iodine is a constituent of thyroid hormones that affect many physiological processes including growth and development, body temperature and heart rate, and bromine is essential for tissue development and architecture. Collisions of neutron stars (kilonovae) have been identified as sources of $r$-process elements including tellurium, which is adjacent to iodine in the periodic table, and lanthanides. Neutron-star collisions arise from energy loss due to gravitational-wave emission from binary systems, leading us to suggest that gravitational waves have played a key role in enabling human life by producing iodine and bromine. We propose probing this proposal by searching in lunar material for live 129I deposited by a recent nearby kilonova explosion.

Aims. As part of the ongoing GRAVITY+ upgrade of the Very Large Telescope Interferometer infrastructure, we aim to improve the performance of the GRAVITY Fringe-Tracker, and to enable its use by other instruments. Methods. We modify the group delay controller to consistently maintain tracking in the white light fringe, characterised by a minimum group delay. Additionally, we introduce a novel approach in which fringe-tracking is performed in the non-observable Optical Path Length state-space, using a covariance-weighted Kalman filter and an auto-regressive model of the disturbance. We outline this new state-space representation, and the formalism we use to propagate the state-vector and generate the control signal. While our approach is presented specifically in the context of GRAVITY/GRAVITY+, it can easily be adapted to other instruments or interferometric facilities. Results. We successfully demonstrate phase delay tracking within a single fringe, with any spurious phase jumps detected and corrected in less than 100 ms. We also report a significant performance improvement, as evidenced by a reduction of about 30 to 40% in phase residuals, and a much better behaviour under sub-optimal atmospheric conditions. Compared to what was observed in 2019, the median residuals have decreased from 150 nm to 100 nm on the Auxiliary Telescopes and from 250 nm to 150 nm on the Unit Telescopes. Conclusions. The improved phase-delay tracking combined with whit light fringe tracking means that from now-on, the GRAVITY Fringe-Tracker can be used by other instruments operating in different wavebands. The only limitation remains the need for an optical path dispersion adjustment.

HD 142527 A is a young and massive Herbig Ae/Be star surrounded by a highly structured disc. The disc shows numerous morphological structures, such as spiral arms, a horseshoe region of dust emission, a set of shadows cast by an inner disc on the outer disc, and a large cavity extending from $\simeq{}$30 au to $\simeq{}$130 au. HD 142527 A also has a lower mass companion, HD 142527 B (M = 0.13 $\pm$ 0.03 $M_\odot{}$), which is thought to be responsible for most of the structures observed in the surrounding disc. We gathered VLTI/GRAVITY observations of HD 142527, either from our own programmes or from the ESO archive. We used this inhomogeneous set of data to extract a total of seven high-precision measurements of the relative astrometry between HD 142527 A and B, spread from mid-2017 to early 2021. Combined with what is available in the literature, we now have 9 yr of astrometric monitoring on HD 142527. We used orbit fitting tools to determine the orbital parameters of HD 142527 B, and used them as inputs for a 3D hydrodynamical model of the disc to determine whether or not the binary is able to create the structures observed in the disc. Our VLTI/GRAVITY astrometry gives excellent constraints on the orbit of HD 142527 B. We show that the secondary is following an orbit of semi-major axis a = 10.80 $\pm$ 0.22 au, with moderate eccentricity (e = 0.47 $\pm$ 0.01). With such a compact orbit, we show that HD 142527 B can only generate a gap and spiral arms of $\sim$30 au in the disc, which is much smaller than what is revealed by observations. Even from a theoretical standpoint, the observed cavity size of $\sim$100 au far exceeds even the most generous predictions for a companion like HD 142527 B on such a compact orbit. Thus, we conclude that the low-mass companion cannot be solely responsible for the observed morphology of the disc surrounding the system.

The first "seeds" of supermassive black holes (BH) can range from $\sim10^2-10^6~M_{\odot}$. However, the lowest mass seeds ($\lesssim10^3 M_{\odot}$) are inaccessible to most cosmological simulations due to resolution limitations. We present our new BRAHMA suite of cosmological simulations that uses a novel flexible seeding approach to represent low mass seeds. Our suite consists of two types of boxes that model $\sim10^3~M_{\odot}$ seeds using two distinct but mutually consistent seeding prescriptions at different simulation resolutions. First, we have the highest resolution $[9~\mathrm{Mpc}]^3$ (BRAHMA-9-D3) boxes that directly resolve $\sim10^3~M_{\odot}$ seeds and place them within halos with dense and metal poor gas. Second, we have lower-resolution and larger-volume $[18~\mathrm{Mpc}]^3$ (BRAHMA-18-E4) and $\sim[36~\mathrm{Mpc}]^3$ (BRAHMA-36-E5) boxes that seed their smallest resolvable $\sim10^4~\&~10^5~\mathrm{M_{\odot}}$ BH descendants using new stochastic seeding prescriptions calibrated using the BRAHMA-9-D3 results. The three boxes together probe BHs between $\sim10^3-10^7 M_{\odot}$ at $z>7$ and we predict their key observables. The variation in the AGN luminosity functions is small (factors of $\sim2-3$) at the anticipated detection limits of potential future X-ray facilities ($\sim10^{43} \mathrm{ergs~s^{-1}}$ at $z\sim7$). Our simulations predict BHs $\sim10-100$ times heavier than expectations from local $M_*$ vs $M_{bh}$ relations, consistent with several JWST-detected AGN. For different seed models, our simulations merge BH binaries at $\sim1-15~\mathrm{kpc}$, with rates of $\sim200-2000$ per year for $\gtrsim10^3 M_{\odot}$ BHs, $\sim6-60$ per year for $\gtrsim10^4~M_{\odot}$ BHs, and up to $\sim10$ per year amongst $\gtrsim10^5 M_{\odot}$ BHs. These results suggest that the LISA mission has promising prospects for constraining seed models.

We use the SAMI galaxy survey to study the the kinematic morphology-density relation: the observation that the fraction of slow rotator galaxies increases towards dense environments. We build a logistic regression model to quantitatively study the dependence of kinematic morphology (whether a galaxy is a fast rotator or slow rotator) on a wide range of parameters, without resorting to binning the data. Our model uses a combination of stellar mass, star-formation rate (SFR), $r$-band half-light radius and a binary variable based on whether the galaxy's observed ellipticity ($\epsilon$) is less than 0.4. We show that, at fixed mass, size, SFR and $\epsilon$, a galaxy's local environmental surface density ($\log_{10}(\Sigma_5/\mathrm{Mpc}^{-2})$) gives no further information about whether a galaxy is a slow rotator, i.e. the observed kinematic-morphology density relation can be entirely explained by the well-known correlations between environment and other quantities. We show how our model can be applied to different galaxy surveys to predict the fraction of slow rotators which would be observed and discuss its implications for the formation pathways of slow rotators.

The irregular satellites of Jupiter produce dust particles through the impact of interplanetary micrometeoroids. In this paper, the dynamics of these particles is studied by both high-accuracy numerical simulation and analytical theory, in order to learn their transport, final fate, and spatial distribution. The perturbation forces that are considered in our dynamical model include the solar radiation pressure, solar gravity, Poynting-Robertson drag, Jovian oblateness, and the Galilean satellites' gravity. The trajectories of different size particles are simulated until they hit Jupiter, the Galilean satellites, or escape from the Jovian system. The average dynamical lifetimes of dust with different grain sizes are calculated, and the final fate of dust particles is reported and analysed. The steady-state spatial number density of particles is estimated by integrating the trajectories of dust particles over their initial size distribution, and compared to the previous work. The impact sites of dust on Callisto's surface are recorded and provide an important clue for the study of the hemisphere asymmetry of Callisto. Besides, the mass accretion rate, cross-sectional area influx, and mass influx density of dust on Callisto are calculated. A ring outside the orbit of Callisto dominated by dust between 2 and 25 ${\mu}$m from Jupiter's irregular satellites is suggested, with the average normal geometric optical depth of the order of $10^{-8}$ and the configuration of the ring ansae similar to Jupiter's gossamer rings.

Cosmological correlators hold the key to high-energy physics as they probe the earliest moments of our Universe, and conceal hidden mathematical structures. However, even at tree-level, perturbative calculations are limited by technical difficulties absent in flatspace Feynman diagrammatics. In this paper, we introduce CosmoFlow: a new accurate open source Python code that computes tree-level cosmological correlators by tracing their time flow. This code is specifically designed to offer a simple, intuitive and flexible coding environment to theorists, primordial and late-time cosmologists. It can typically serve to complement analytical computations, to provide physical intuition when studying various inflationary theories, and to obtain exact results in regimes that are analytically out of reach. This paper presents the basic structure of CosmoFlow, leads the reader through an in-depth user-guide, and illustrates how it can be used with a series of worked examples. Our hope is that this first building block sets the stage for a bank of theoretical data, which can be nurtured and enhanced collaboratively by the community. CosmoFlow is publicly available on GitHub.

Observations of GW170817 strongly suggest that binary neutron star (BNS) mergers can produce rapid neutron-capture nucleosynthesis (r-process) elements. However, it remains an open question whether BNS mergers can account for all the r-process element enrichment in the Milky Way's history. Here we demonstrate that a BNS population model informed by multimessenger neutron star observations predicts a merger rate and per-event r-process element yield consistent with geophysical and astrophysical abundance constraints. If BNS mergers are to explain the r-process enrichment of stars in the Galaxy, we further show using a one-zone Galactic chemical evolution model that they have to merge shortly after the formation of their progenitors, with a delay time distribution of power-law index $\alpha\leq -2.0$ and minimum delay time $t_{\rm min}\leq 40$ Myr at 90% confidence. Such short delay times are in tension with those inferred from short gamma-ray bursts (sGRBs) and those predicted by standard BNS formation models. However, we find that a two-channel enrichment scenario, where the second channel follows the star formation history, can account for both Galactic stellar and sGRB observations. Our results suggest that 40-90% of the r-process abundance in the Milky Way today was produced by a star-formation-tracking channel, rather than BNS mergers with sGRB-compatible delay times.

Black hole dynamics suggests that dark matter would re-distribute near a supermassive black hole to form a density spike. However, no direct evidence of dark matter density spike around a supermassive black hole has been identified. In this letter, we present the first robust evidence showing a dark matter density spike around a supermassive black hole. We revisit the data of the well-known supermassive black hole binary OJ 287 and show that the inclusion of the dynamical friction due to a dark matter density spike around the supermassive black hole can satisfactorily account for the observed orbital decay rate. The derived spike index $\gamma_{\rm sp}=2.351^{+0.032}_{-0.045}$ gives an excellent agreement with the value $\gamma_{\rm sp}=2.333$ predicted by the benchmark model assuming an adiabatically growing supermassive black hole. This provides a strong verification of the canonical theory suggested two decades ago modeling the gravitational interaction between collisionless dark matter and supermassive black holes.

The reionization of the second electron of helium (HeII) leaves important imprints on the thermal and ionization state of the intergalactic medium (IGM). Observational evidence suggests that HeII reionization ended at $z \simeq 3$ due to ionizing photons emitted predominantly by quasars. We present efficient semi-numerical simulations of helium reionization in a $230 \ \mathrm{h^{-1}~Mpc}$ box, that takes into account the spatial patchiness of reionization coupled with photoheating of the IGM. Dark matter haloes are assigned quasars using empirical measurements of the quasar luminosity function, assuming a universal quasar lifetime consistent with duty cycle values inferred from measurements of the quasar clustering. The ionizing photon field from quasars is then included in the semi-numerical Code for ReionIzation with PhoTon conservation (SCRIPT), which was originally developed for modeling hydrogen reionization. In this work, we make appropriate modifications to SCRIPT for modeling inhomogenous HeII reionization and the corresponding thermal history of the IGM is modelled via a subgrid prescription. Our model has three main free parameters i.e. the global clumping factor $\mathcal{C}_{HeIII}$, the temperature increase due to photoheating $T^{re}_{He}$ and the quasar spectral energy distribution (SED) index, $\alpha_{UV}$. Our \textit{fiducial} model with $\mathcal{C}_{HeIII}=15.6$ and $T^{re}_{He} \sim 6000 \ K$ gives reasonable values for the empirical measurements of the temperature density equation of state at these redshifts, assuming that quasars brighter than $\mr{M_{1450}}<-21$ and having $\alpha_{UV}=1.7$ contribute to HeII reionization. The efficiency of our code shows promising prospects for performing parameter estimation in future, for models of HeII reionization using observations of the Ly$\alpha$ forest.

The Spectrometer/Telescope for Imaging X-rays (STIX) is a hard X-ray imaging spectrometer on board the ESA and NASA heliospheric mission Solar Orbiter. STIX has been operational for three years and has observed X-ray emission from ~35,000 solar flares. Throughout its lifetime, Solar Orbiter has been frequently struck by a high flux of energetic particles usually of flare origin, or from coronal mass ejection shocks. These Solar Energetic Particles (SEPs) are detected on board by the purpose-built energetic particle detector instrument suite. During SEP events, the X-ray signal is also contaminated in STIX. This work investigates the effect of these particles on the STIX instrument for two events. The first event occurred during an interplanetary shock crossing and the second event occurred when Solar Orbiter passed through Earth's radiation belts while performing a gravity assist maneuver. The induced spectra consist of tungsten fluorescence emission lines and secondary Bremsstrahlung emission produced by incident particles interacting with spacecraft components. For these two events, we identify > 100 keV electrons as significant contributors to the contamination via Bremsstrahlung emission and tungsten fluorescence.

Some high-z active galactic nuclei (AGNs) are found to reside in extreme star-forming galaxies, such as hyper-luminous infrared galaxies (HyLIRGs), with AGN-removed $L_{\rm{IR}}$ of $>10^{13} L_{\rm{\odot}}$. In this paper, we report NOEMA observations of six apparent starburst HyLIRGs associated with optical quasars at $z\sim2-3$ in the Stripe 82 field, to study their dust and molecular CO properties. Five out of the six candidates are detected with CO(4-3) or CO(5-4) emission, and four in 2mm dust continuum. Based on the linewidth-$L'_{\rm{CO(1-0)}}$ diagnostics, we find that four galaxies are likely unlensed or weakly lensed sources. The molecular gas mass is in the range of $\mu M_{\rm{H_2}} \sim0.8-9.7\times10^{10} M_{\odot}$ (with $\alpha = 0.8 M_{\odot} (\rm{K km s^{-1} pc^2})^{-1}$ and $\mu$ is the unknown possible gravitational magnification factor). We fit their SEDs, after including the observed 2mm fluxes and upper limits, and estimate their apparent (uncorrected for possible lensing effect) star formation rates ($\mu$SFRs) to be $\sim400-2500$ $M_{\rm{\odot}} \rm{yr^{-1}}$ with depletion time of $\sim20-110$ Myr. We notice interesting offsets, of $\sim10-40$ kpc spatially or $\sim1000-2000$ km s$^{-1}$ spectroscopically, between the optical quasar and the mm continuum or CO emissions. The observed velocity shift is likely related to the blueshifted broad-emission-line region of quasars, though mergers or recoiling black holes are also possible causes, which can explain the spatial offset and the high intrinsic SFRs in the HyLIRG-quasar systems.

Thermal radiation becomes a prominent feature in the continuum spectrum of Venus longwards of $\sim$3 $\mu$m. The emission is traceable to the upper cloud and haze layers in the planet's mesosphere. Venus' thermal radiation spectrum is punctuated by CO$_2$ bands of various strengths probing into different atmospheric depths. It is thus possible to invert measured spectra of thermal radiation to infer atmospheric temperature profiles and offer some insight into the cloud and haze structure. In practice, the retrieval becomes complicated by the fact that the outgoing radiation is multiply scattered by the ubiquitous aerosol particles before leaving the atmosphere. We numerically investigate the radiative transfer problem of thermal radiation from the Venus night side between 3 and 5 $\mu$m with a purpose-built model of Venus' mesosphere. Special emphasis is laid on the significance of scattering. The simulations explore the space of model parameters, which includes the atmospheric temperature, cloud opacity, and the aerosols' size and chemical composition. We confirm that aerosol scattering must be taken into account in a prospective temperature retrieval, which means an additional complication to the already ill-posed retrieval problem. We briefly touch upon the degeneracy in the spectrum's shape associated with parameterization of the Venus clouds. Reasonable perturbations in the chemical composition and size of aerosols do not significantly impact the model simulations. Although the experiments are specific to the technical characteristics of the Visual and Infrared Thermal Imaging Spectrometer on the Venus Express spacecraft, the conclusions are generally valid.

The detection of gravitational waves (GWs) from binary black hole (BBH) coalescences by the LIGO-Virgo-KAGRA (LVK) Collaboration has raised fundamental questions about the genesis of these events. In this chapter, we explore the possibility that PBHs, proposed candidates for dark matter, may serve as the progenitors of the BBHs observed by LVK. Employing a Bayesian analysis, we constrain the PBH model using the LVK third GW Transient Catalog (GWTC-3), revealing that stellar-mass PBHs cannot dominate cold dark matter. Considering a mixed population of astrophysical black holes (ABHs) and PBHs, we determine that approximately $1/4$ of the detectable events in the GWTC-3 can be attributed to PBH binaries. We also forecast detectable event rate distributions for PBH and ABH binaries by the third-generation ground-based GW detectors, such as the Einstein Telescope, offering a potential avenue to distinguish PBHs from ABHs based on their distinct redshift evolutions.

Target of NASA's DART mission, the system of Didymos and Dimorphos will once again be visited by a space mission -- ESA's Hera mission, scheduled to be launch in 2024. Hera will arrive in the system approximately 4 years after the DART impact, a long period compared to Dimorphos' orbital period (about 12 hours). It is therefore imperative to understand the dynamics of material in this environment on a long timescale. Here, we explore the long-term dynamics of the binary system (65038) Didymos, in the context of the perturbed, planar, circular and restricted 3-body problem. We design an analytical description for a symmetrical top-shaped object, the shape assumed for the Didymos, while the Dimorphos is considered an ellipsoid. In the absence of external effects, we identify seven stable equatorial regions where particles persist for more than a decade. However, in the presence of the solar radiation effect, the lifetime of small particles (<mm) is in the order of days, being unlikely that Hera spacecraft will encounter clusters of millimetre and sub-millimetre particles in stable equatorial orbits. Nonetheless, large objects may reside in the region for some years, particularly in quasi-satellite orbits, the most stable orbits in the system. Additionally, interplanetary dust impacts onto Didymos populate the region, extending up to a distance of approximately 1500 meters from the primary center, with young dust. These impacts are responsible for a transfer of dust mainly from Didymos to Dimorphos. If the interplanetary dust impacts generate metric-sized boulders, they may persist in the system for years, in first sort orbits around Didymos.

The innermost regions of Active Galactic Nuclei (AGN) are critical for understanding galaxy evolution and the dynamics of matter near a Supermassive Black Hole (SMBH). Yet, due to smaller angular projections, it is very difficult to resolve these regions. This thesis explores indirect methods to understand these objects. We use the reverberation mapping technique to estimate accretion disk sizes for a sample of AGN, finding that the computed disk sizes are, on average, 3.9 times larger than the Shakura Sunyev (SS) standard disk model predictions. We also find a weak correlation between the obtained accretion disk sizes and the SMBH mass. We present initial results from a new accretion disk monitoring program to probe the accretion disk structure of Super Eddington Accreting AGN. We report that the disk sizes are about 4 times larger than the SS disk model. We calibrate the narrow-band photometric reverberation mapping (PRM) technique to develop tools for a large systematic narrow-band PRM project. We use simulations to test the effect of cadence, variability of the light curves, and the length of light curves in recovering the reverberation lags. We study the dichotomy between AGNs with and without detected jets using the method of microvariability observed in the accretion disk continuum. We find that AGNs with confirmed jets are about 3 times more variable on short time scales than the AGNs without a confirmed jet. By performing statistical analysis on a large sample of low luminosity AGNs, we find that the NLSy1 galaxies are more likely to have outflow signatures than their broad-line counterparts, hinting toward the disk wind origin of the material in BLR. We find that the principal components for NLSy1 galaxies differ from the BLSy1 galaxies, suggesting that the NLSy1 galaxies could be occupying their own parameter space.

Observations of disks with the Atacama Large Millimeter/submillimeter Array (ALMA) allow us to map the chemical makeup of nearby protoplanetary disks with unprecedented spatial resolution and sensitivity. The typical outer Class II disk observed with ALMA is one with an elevated C/O ratio and a lack of oxygen-bearing complex organic molecules, but there are now some interesting exceptions: three transition disks around Herbig Ae stars all show oxygen-rich gas traced via the unique detections of the molecules SO and CH3OH. We present the first results of an ALMA line survey at 337 to 357 GHz of such disks and focus this paper on the first Herbig Ae disk to exhibit this chemical signature - HD 100546. In these data, we detect 19 different molecules including NO, SO and CH3OCHO (methyl formate). We also make the first tentative detections of H213CO and 34SO in protoplanetary disks. Multiple molecular species are detected in rings, which are, surprisingly, all peaking just beyond the underlying millimeter continuum ring at 200 au. This result demonstrates a clear connection between the large dust distribution and the chemistry in this flat outer disk. We discuss the physical and/or chemical origin of these sub-structures in relation to ongoing planet formation in the HD 100546 disk. We also investigate how similar and/or different the molecular make up of this disk is to other chemically well-characterised Herbig Ae disks. The line-rich data we present motivates the need for more ALMA line surveys to probe the observable chemistry in Herbig Ae systems which offer unique insight into the composition of disk ices, including complex organic molecules.

The Atacama Large Millimeter/submillimeter Array (ALMA) can probe the molecular content of planet-forming disks with unprecedented sensitivity. These observations allow us to build up an inventory of the volatiles available for forming planets and comets. Herbig Ae transition disks are fruitful targets due to the thermal sublimation of complex organic molecule (COM) and likely H2O-rich ices in these disks. The IRS 48 disk shows a particularly rich chemistry that can be directly linked to its asymmetric dust trap. Here, we present ALMA observations of the IRS 48 disk where we detect 16 different molecules and make the first robust detections of H213CO, 34SO, 33SO and c-H2COCH2 (ethylene oxide) in a protoplanetary disk. All of the molecular emissions, aside from CO, are colocated with the dust trap and this includes newly detected simple molecules such as HCO+, HCN and CS. Interestingly, there are spatial offsets between different molecular families, including between the COMs and sulphur-bearing species, with the latter being more azimuthally extended and located radially further from the star. The abundances of the newly detected COMs relative to CH3OH are higher than the expected protostellar ratios, which implies some degree of chemical processing of the inherited ices during the disk lifetime. These data highlight IRS 48 as a unique astrochemical laboratory to unravel the full volatile reservoir at the epoch of planet and comet formation and the role of the disk in (re)setting chemical complexity.

We provide a new $Y_{SZ} - M_{500}^{Y_X}$ scaling relation using a sample of clusters from the Planck Early Sunyaev-Zeldovich (ESZ) catalogue observed in X-rays by Chandra, and compare it to the results of the Planck collaboration from XMM-Newton observations of a subsample of the ESZ. We calibrate a mass bias for a subset of the Planck cosmological cluster sample using published weak-lensing data from the Canadian Cluster Cosmology Project and Multi Epoch Nearby Cluster Survey, for the new scaling relation as well as that from the Planck collaboration. We propose a novel method to account for selection effects and find a mass bias of $(1-b)=0.89\pm0.04$ for the new scaling relation, and $(1-b)=0.76\pm0.04$ for the Planck scaling relation. With these mass biases, we obtain $Y_{SZ} - M_{500}$ scaling relations that we apply to the full Planck cosmological cluster sample, to obtain new constraints on the cosmological parameters. We find fully consistent constraints regardless of the X-ray sample used, with $\sigma_8 = 0.77\pm0.02$, $\Omega_m = 0.31\pm0.02$ and $S_8 \equiv \sigma_8 \sqrt{\Omega_m / 0.3}=0.78\pm0.02$. We also provide constraints with a redshift evolution of the scaling relation fitted from the data instead of fixing it to the self-similar value. We find a redshift evolution significantly deviating from the self-similar value, leading to a higher value of $S_8=0.81\pm0.02$. We compare our results to those from recent analyses based on various cosmological probes, and find that our $S_8$ constraints are competitive with the tightest constraints from the literature. When assuming a self-similar redshift evolution, our constraints are in agreement with most late time probes and in tension with constraints from the CMB primary anisotropies. When fitting the redshift evolution from the data, we find no significant tension with results from either late time probes or the CMB.

The Cosmic Dawn marks the first star formations and preceded the Epoch-of-Reionization, when the Universe underwent a fundamental transformation propelled by the radiation from these first stars and galaxies. Interferometric 21-cm experiments aim to probe redshifted neutral hydrogen signals from these periods, constraining the conditions of the early Universe. The SKA-LOW instrument of the Square Kilometre Array telescope is envisaged to be the largest and most sensitive radio telescope at m and cm wavelengths. The latest Aperture Array Verification Systems feature 7m coaxial transmission lines connecting the Low Noise Amplifiers to optical transmitters at the front of the analogue-receiving chain. An impedance mismatch between these components results in a partially reflected electromagnetic signal, which introduces chromatic aberrations in the instrument bandpass. This causes power from the foreground signals to appear at higher delays, potentially contaminating the EoR window, a region at which the 21-cm signal should be detectable. We present an end-to-end simulation pipeline for SKA-LOW using a composite sky model combining radio foregrounds from The GLEAM Survey, Haslam $408$MHz, and a $1.5$cGpc 21-cm brightness temperature cube generated with the 21cmSPACE simulator. Iterating a parametric approach, we derive a model for the scattering parameters of a coaxial transmission line in terms of its specifications and bulk material properties. Assuming identical cables of length $\leq 15.0$m with impedance mismatch $\leq 10\Omega$ confines the reflection to k-modes below the EoR window. However, we demonstrate that even a $0.1$% length tolerance introduces contamination with an RMSE of $\sim 10$% across all accessible k-modes.

Recent studies suggest that high-energy neutrinos can be produced in the jets of blazars, radio-loud active galactic nuclei (AGN) with jets pointing close to the line of sight. Due to the relatively poor angular resolution of current neutrino detectors, several sources can be regarded as the possible counterpart of a given neutrino event. Therefore, follow-up observations of counterpart candidates in the electromagnetic regime are essential. Since the Very Long Baseline Interferometry (VLBI) technique provides the highest angular resolution to study the radio jets of blazars, a growing number of investigations are being conducted to connect individual blazars to given high-energy neutrino events. We analyzed more than 20 years of available archival VLBI data of the blazar CTD 74, which has been listed as a possible counterpart of a neutrino event. Using cm-wavelength data, we investigated the jet structure, determined the apparent speed of jet components, and the core flux density before and after the neutrino event. Our results indicate stationary jet features and a significant brightening of the core after the neutrino event.

Several Lyman Continuum (LyC) emitters have been detected so far, but their observed ionising spectra sometimes differ from attenuated stellar spectra predicted by stellar population synthesis modelling. This discrepancy may be due to a significant contribution of LyC nebular emission. We aim to quantify the importance this emission in LyC leakers: its contribution to the ionising photons budget, and to measurements of LyC escape. To estimate the nebular contribution to the LyC spectra of galaxies, we run photoionisation models with Cloudy for a range of BPASS templates, varying the column density of the surrounding gas, from density-bounded (log(NH$_{\rm{stop}}$/cm$^{-2}$)=16) to ionisation-bounded (log(NH$_{\rm{stop}}$/cm$^{-2}$)=19) regimes. In the limits of very optically thin (f$_{\rm{esc}}$ = 1), or thick configurations (f$_{\rm{esc}}$ = 0), there is no nebular contribution to the emergent LyC spectra. This contribution matters only at intermediate LyC opacities ($0 <$ f$_{\rm{esc}}$ $< 1$), where it alters the shape of the LyC spectrum chromatically, so that escape fractions estimates are highly sensitive to the wavelength range over which they are calculated. We propose a formula to estimate integrated escape fractions using f$_{\lambda 700}$/f$_{\lambda 1100}$ flux ratios, since this wavelength range is not affected by nebular emission. Regarding simulations, the boost of hydrogen ionising photons escaping galaxies is inversely proportional to the stellar escape fractions, but since typical simulated escape fractions are low, LyC photons escape is important. Nebular LyC is a non-negligible additional source of ionising photons from galaxies, which contribution has been overlooked so far in observations and in cosmic reionisation simulations.

Global Climate Models (GCM) are very useful tools to study theoretically the general dynamics and specific phenomena in planetary atmospheres. In the case of Venus, several GCMs succeeded in reproducing the atmosphere's superrotation and the global temperature field. However, the highly variable polar temperature and the permanent cold collar have not been reproduced satisfactorily yet. Here we improve the radiative transfer scheme of the Institut Pierre Simon Laplace Venus GCM in order to numerically simulate the polar thermal features in Venus atmosphere. The main difference with the previous model is that we now take into account the latitudinal variation of the cloud structure. Both solar heating rates and infrared cooling rates have been modified to consider the cloud top's altitude decrease toward the poles and the variation in latitude of the different particle modes' abundances. A new structure that closely resembles the observed cold collar appears in the average temperature field at $2\times10^{4} - 4\times10^{3}$~Pa ($\sim62 - 66$~km) altitude range and $60^{\circ} - 90^{\circ}$ latitude band. It is not isolated from the pole as in the observation-based maps, but the obtained temperature values (220~K) are in good agreement with observed values. Temperature polar maps across this region show an inner warm region where the polar vortex is observed, but the obtained 230~K average value is colder than the observed mean value and the simulated horizontal structure does not show the fine-scale features present within the vortex. Our study shows that the cloud structure is essential in the cold collar formation. Although our analysis focuses on the improvement of the radiative forcing and the variations it causes in the thermal structure, polar dynamics is definitely affected by this modified environment and a noteworthy upwelling motion is found in the cold collar area.

We present iSLAT (the Interactive Spectral-Line Analysis Tool), a python-based graphical tool that allows users to interactively explore and manually fit line emission observed in molecular spectra. iSLAT adopts a simple slab model that simulates emission spectra with a small set of parameters (temperature, emitting area, column density, and line broadening) that users can adjust in real time for multiple molecules or multiple thermal components of a same molecule. A central feature of iSLAT is the possibility to interactively inspect individual lines or line clusters to visualize their properties at high resolution and identify them in the population diagram. iSLAT provides a number of additional features, including the option to identify lines that are not blended at the instrumental resolution, the possibility to save custom line lists selected by the user, and to fit and measure their properties (line flux, width, and centroid) for later analysis. In this paper we launch the tool and demonstrate it on infrared spectra from the James Webb Space Telescope and ground-based instruments that provide higher resolving power. We also share curated line lists that are useful for the analysis of the forest of water emission lines observed from protoplanetary disks. iSLAT is shared with the community on GitHub.

Ultra-light dark matter perturbs the orbital motion of binary pulsars, in particular by causing peculiar time variations of a binary's orbital parameters, which then induce variations in the pulses' times-of-arrival. Binary pulsars have therefore been shown to be promising detectors of ultra-light dark matter. To date, the sensitivity of binary pulsars to ultra-light dark matter has only been studied for dark matter masses in a narrow resonance band around a multiple of the binary pulsar orbital frequency. In this study we devise a two-step, bayesian method that enables us to compute semi-analytically the sensitivity for all masses, also away from the resonance, and to combine several observed binaries into one global sensitivity curve. We then apply our method to the case of a universal, linearly-coupled, scalar ultra-light dark matter. We find that with next-generation radio observatories the sensitivity to the ultra-light dark matter coupling will surpass that of solar-system constraints for a decade in mass around $m\sim10^{-21}$ $\text{eV}$, even beyond resonance.

The number of super-Earth and mini-Neptune planet discoveries has increased significantly in the last two decades thanks to transit and radial velocity surveys. When it is possible to apply both techniques, we can characterise the internal composition of exoplanets, which in turn provides unique insights on their architecture, formation and evolution. We performed a combined photometric and radial velocity analysis of TOI-238 (TYC 6398-132-1), which has one short-orbit super-Earth planet candidate announced by NASA's TESS team. We aim to confirm its planetary nature using radial velocities taken with the ESPRESSO and HARPS spectrographs, to measure its mass and to detect the presence of other possible planetary companions. We carried out a joint analysis by including Gaussian processes and Keplerian orbits to account for the stellar activity and planetary signals simultaneously. We detected the signal induced by TOI-238 b in the radial velocity time-series, and the presence of a second transiting planet, TOI-238 c, whose signal appears in RV and TESS data. TOI-238 b is a planet with a radius of 1.402$^{+0.084}_{-0.086}$ R$_{\oplus}$ and a mass of 3.40$^{+0.46}_{-0.45}$ M$_{\oplus}$. It orbits at a separation of 0.02118 $\pm$ 0.00038 AU of its host star, with an orbital period of 1.2730988 $\pm$ 0.0000029 days, and has an equilibrium temperature of 1311 $\pm$ 28 K. TOI-238 c has a radius of 2.18$\pm$ 0.18 R$_{\oplus}$ and a mass of 6.7 $\pm$ 1.1 M$_{\oplus}$. It orbits at a separation of 0.0749 $\pm$ 0.0013 AU of its host star, with an orbital period of 8.465652 $\pm$ 0.000031 days, and has an equilibrium temperature of 696 $\pm$ 15 K. The mass and radius of planet b are fully consistent with an Earth-like composition, making it likely a rocky super-Earth. Planet c could be a water-rich planet or a rocky planet with a small H-He atmosphere.

We present a comprehensive investigation on the mass function (MF) of a snake-like stellar structure in the solar neighbourhood, building on our previous discovery. To ensure the reliability of the data, we reselect the member stars of the Stellar ``Snake'' in the latest {\it Gaia} Data Release 3 using the same approach as the initial series of articles. We also precisely measure the physical parameters of the clusters within the Stellar Snake. In light of the high completeness of the member stars in the cluster regions, we develop a simulated model color-magnitude diagram-based inference method to derive the mass function, binary fraction, and mass-ratio distribution of the clusters in the Stellar Snake. Notably, despite their similar ages and metallicity, we discover systematic variations in the MFs along the elongation direction of the Snake in the mass range of 0.5 to 2.0 M$_\odot$. The ``head'' of the Snake conforms to a canonical initial mass function with a power-law slope of $\alpha\sim-2.3$. Extending towards the ``tail,'' the MF becomes more top-light, indicating a deficiency of massive stars within these clusters. This result provides evidence for the delayed formation of massive stars in the clusters. Such clues give support to the hypothesis that the Stellar Snake constitutes as a hierarchically primordial structure.

On 2022 September 26th, 23:14 UT the NASA/DART (Double Asteroid Redirection Test) spacecraft successfully impacted Dimorphos, the secondary component of the binary (65803) Didymos system, demonstrating asteroid orbit deflection for the first time. A large amount of debris, consisting on a wide size frequency distribution of particulates (from micron-sized dust to meter-sized boulders), was released, and a long-lasting tail has been observed over more than 9 months since impact. An important fraction of the ejecta mass has been ejected as individual meter-sized boulders, as have been found in images obtained by the Light Italian CubeSat for Imaging of Asteroid (LICIACube), as well as from the Hubble Space Telescope (HST). While the boulders observed by LICIACube had projected speeds of several tens of meter per second, those seen by the HST were about one hundred time slower. In this paper we analyze the long-term orbital evolution of those slow boulders using different dynamical codes, providing constraints on the fate of such large particles, and giving insight on the possibility of observing some of those boulders that might remain in orbit at the time of the ESA/Hera mission arrival to the binary system in late 2026.

Slow first-order phase transitions generate large inhomogeneities that can lead to the formation of primordial black holes (PBHs). We show that the gravitational wave (GW) spectrum then consists of a primary component sourced by bubble collisions and a secondary one induced by large perturbations. The latter gives the dominant peak if $\beta/H_0 < 10$, impacting, in particular, the interpretation of the recent PTA data. The GW signal associated with a particular PBH population is stronger than in typical scenarios because of a negative non-Gaussianity of the perturbations and it has a distinguishable shape with two peaks.

Through continuous progress in nuclear theory and experiment and an increasing number of neutron-star observations, a multitude of information about the equation of state (EOS) for matter at extreme densities is available. Here, we apply these different pieces of data individually to a broad set of physics-agnostic candidate EOSs and analyze the resulting constraints. Specifically, we make use of information from chiral effective field theory, perturbative quantum chromodynamics, as well as data from heavy-ion collisions and the PREX-II and CREX experiments. We also investigate the impact of current mass and radius measurements of neutron stars, such as radio timing measurements of heavy pulsars, NICER data, and other X-ray observations. We augment these by reanalyses of the gravitational-wave (GW) signal GW170817, its associated kilonova AT2017gfo and gamma-ray burst afterglow, the GW signal GW190425, and the GRB211211A afterglow, where we use improved models for the tidal waveform and kilonova light curves. Additionally, we consider the postmerger fate of GW170817 and its consequences for the EOS. This large and diverse set of constraints is eventually combined in numerous ways to explore limits on quantities such as the typical neutron-star radius, the maximum neutron-star mass, the nuclear symmetry-energy parameters, and the speed of sound. Based on the priors from our EOS candidate set, we find the radius of the canonical 1.4 M$_\odot$ neutron star to be $R_{1.4}= 12.27_{-0.94}^{+0.83}$ km and the TOV mass $M_{\rm TOV}= 2.26_{-0.22}^{+0.45}$ M$_\odot$ at 95% credibility, when including those constraints where systematic uncertainties are deemed small. A less conservative approach, combining all the presented constraints, similarly yields $R_{1.4}= 12.20_{-0.50}^{+0.53}$ km and $M_{\rm TOV}= 2.31_{-0.20}^{+0.08}$ M$_\odot$.

Spectra of young benchmark brown dwarfs with well-known ages are vital to characterize other brown dwarfs, for which ages are in general not known. These spectra are also crucial to test atmospheric models which have the potential to provide detailed information about the atmospheres of these objects. However, to optimally test atmospheric models, medium-resolution, long-wavelength coverage spectra with well-understood uncertainties are ideal, such as the spectra provided by the NIRSpec instrument onboard the James Webb Space Telescope. In this paper, we present the medium-resolution JWST/NIRSpec spectra of two young brown dwarfs, TWA 28 (M9.0) and TWA 27A (M9.0), and one planetary-mass object, TWA 27B (L6.0), members of the TW Hydrae Association (~10 Myr). We show the richness of the atomic lines and molecular bands present in the spectra. All objects show signs of a circumstellar disk, via near-infrared excess and/or via emission lines. We matched a set of cloudless atmospheric spectra (ATMO), and cloudy atmospheric spectra (BT-Settl) to our NIRSpec spectra, and analyzed which wavelength ranges and spectral features both models reproduce best. Both models derive consistent parameters for the three sources, and predict the existence of CH4 at 3.35 microns in TWA 27B. Nonetheless, in contrast to other slightly older objects with similar spectral type, like PSO 318.5-22 and VHS 1256b, this feature is not present in the spectrum of TWA 27B. The lack of the CH4 feature might suggest that the L/T transition of very young dwarfs starts at later spectral types than for older brown dwarfs.

We have analyzed the deconvolved surface brightness profiles of 247 massive and angularly large disk galaxies at $1\leq z\leq 3$ to study high-redshift disk breaks, using F356W-band images from the Cosmic Evolution Early Release Science survey. We found that 12.6% of these galaxies have Type I (exponential) profiles, 56.7% have Type II (down-bending) profiles, and 34.8% have Type III (up-bending) profiles. Moreover, we showed that galaxies that are more massive, centrally concentrated, or redder, tend to show fewer Type II and more Type III breaks. These fractions and the detected dependencies on galaxy properties are in good agreement with those observed in the local Universe. In particular, the ratio of the Type II disk break radius to the bar radius in barred galaxies typically peaks at a value of 2.25, perhaps due to bar-induced radial migration. However, the timescale for secular evolution may be too lengthy to explain the observed breaks at such high redshifts. Instead, violent disk instabilities may be responsible, where spiral arms and clumps torque fling out the material, leading to the formation of outer exponential disks. Our results provide further evidence for the assertion that the Hubble Sequence was already in place during these early periods.

The QCD axion can solve the Strong CP Problem and be the dark matter of our universe. If the PQ symmetry breaking scale associated with the axion is below the inflationary reheating temperature, axion strings and domain walls populate the universe. Most of these strings and walls decay away into axion dark matter, but a small subset of the walls will be self-enclosed surfaces that are not attached to any strings. These enclosed walls can collapse in on themselves, compressing a large amount of energy into a small volume and potentially forming primordial black holes (PBHs). We study the number density and dynamics of these self-enclosed walls, taking into account their size distribution, Hubble expansion, asphericities, and all stages of domain wall dynamics using a combination of semi-analytic and numerical approaches. We find that axion models with a high axion decay constant $f_a$, such as those of interest in early matter-dominated cosmologies, yield a PBH abundance potentially observable by future gravitational lensing surveys. We note that the formalism developed here is also useful for predicting relic PBH abundances in other models that exhibit unstable domain walls.

Early dark energy (EDE), introduced at the epoch of matter-radiation equality to alleviate the Hubble tension, has posed a new coincidence problem: why EDE appears at matter-radiation equality when their physics are completely unrelated? To solve this coincidence problem, we propose a new EDE model based on scalar-tensor gravity with the idea that EDE is triggered by spacetime dynamics that encodes cosmic radiation-matter transition. Our model can induce EDE naturally at matter-radiation equality without unnatural parameter tuning. Compared with other EDE models, a distinguishing feature of ours is that it can also induce a new energy component during cosmic matter-dark energy transition. This is testable with low-redshift observations.

We explore gravity-independent equations of state for neutron stars, particularly focusing on twin stars. Examining four categories, we emphasize their behavior in both General Relativity and Palatini gravity. Additionally, we discuss a subcategory of type I, which, in the context of General Relativity, does not exhibit twin star phenomena, yet demonstrates this phenomenon in modified gravity. Furthermore, we briefly address challenges associated with the negative trace of the energy-momentum tensor, prevalent in both theories.

The pulsar timings are sensitive to both the nanohertz gravitational-wave background and the oscillation of ultralight dark matter. The Hellings-Downs angular correlation curve provides a criterion to search for stochastic gravitational-wave backgrounds at nanohertz via pulsar timing arrays. We study the angular correlation of the timing residuals induced by the spin-2 ultralight dark matter, which is different from the usual Hellings-Downs correlation. At a typical frequency, we show that the spin-2 ultralight dark matter can give rise to the deformation of the Hellings-Downs correlation curve induced by the stochastic gravitational wave background.

Stratospheric balloons have emerged as an affordable and flexible alternative to traditional spacecrafts as they are implemented using commercial off-the-shelf (COTS) equipment without following strict methodologies. HERCCULES is a stratospheric balloon mission that aims to characterize the convective heat and radiative environment in the stratosphere. The purpose of this article is to present the HERCCULES onboard software (OBSW) whose design and complexity is comparable to that of satellite systems, since it must control about sixty COTS equipment using a single Raspberry Pi 4B as onboard computer and ensure the real-time requirements. Compared to similar systems, novel contributions are presented as the OBSW is developed following modelbased and component-based approaches using the TASTE toolchain from the European Space Agency (ESA) for automatic code generation. Besides, the OBSW is verified and validated following the ESA standards and the results obtained demonstrate the suitability and efficiency of the solution and the selected methodologies.