Papers for Thursday, Jan 26 2023

We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six clusters. We combine these results with four additional clusters studied by Healy & McCullough (2020) and Healy et al. (2021) to perform an ensemble analysis of their spins. We find that eight out of ten constrained clusters (80%) have spin-axis orientations consistent with isotropy, and we establish a lower limit of four out of ten (40%) isotropic clusters at 75% confidence, assuming no correlation of spins between clusters. We also identify two clusters whose spin-axis distributions can be better described by a model consisting of an aligned fraction of stars combined with an isotropic distribution. However, the inclination values of these stars may be influenced by systematic error, and the small number of stars modeled as aligned in these two clusters precludes the interpretation that their stellar subsets are physically aligned. Overall, no cluster displays an unambiguous signature of spin alignment, and 97% of the stars in our sample are consistent with isotropic orientations in their respective clusters. Our results offer support for the dominance of turbulence over ordered rotation in clumps and do not suggest alignment of rotation axes and magnetic fields in protostars.

We use passive gas tracer particles in an Arepo simulation of a dwarf spiral galaxy to relate the Lagrangian evolution of star-forming gas parcels and their H2 molecules to the evolution of their host giant molecular clouds. We find that the median chemical lifetime of H2 is just 4 Myr, independent of the lifetime of its host molecular cloud, which may vary from 1 to 90 Myr, with a substantial portion of all star formation in the galaxy occurring in relatively long-lived clouds. The rapid ejection of gas from around young massive stars by early stellar feedback is responsible for this short H2 survival time, driving down the density of the surrounding gas, so that its H2 molecules are dissociated by the interstellar radiation field. This ejection of gas from the H2-dominated state is balanced by the constant accretion of new gas from the galactic environment, constituting a "competition model" for molecular cloud evolution. Gas ejection occurs at a rate that is proportional to the molecular cloud mass, so that the cloud lifetime is determined by the accretion rate, which may be as high as 4 x 10^4 Msol/Myr in the longest-lived clouds. Our findings therefore resolve the conflict between observations of rapid gas ejection around young massive stars and observations of long-lived molecular clouds in galaxies, that often survive up to several tens of Myr. We show that the fastest-accreting, longest-lived, highest-mass clouds drive supernova clustering on sub-cloud scales, which in turn is a key driver of galactic outflows.

We present a high-cadence multi-epoch analysis of dramatic variability of three broad emission lines (MgII, H$\beta$, and H$\alpha$) in the spectra of the luminous quasar ($\lambda L_{\lambda}$(5100\r{A}) = $4.7 \times 10^{44}$ erg s$^{-1}$) SDSS J141041.25+531849.0 at $z = 0.359$ with 127 spectroscopic epochs over 9 years of monitoring (2013-2022). We observe anti-correlations between the broad emission-line widths and flux in all three emission lines, indicating that all three broad emission lines "breathe" in response to stochastic continuum variations. We also observe dramatic radial velocity shifts in all three broad emission lines, ranging from $\Delta{v}$ $\sim$400 km s$^{-1}$ to $\sim$800 km s$^{-1}$, that vary over the course of the monitoring period. Our preferred explanation for the broad-line variability is complex kinematics in the broad-line region gas. We suggest a model for the broad-line variability that includes a combination of gas inflow with a radial gradient, an azimuthal asymmetry (e.g., a hot spot), superimposed on the stochastic flux-driven changes to the optimal emission region ("line breathing"). Similar instances of line-profile variability due to complex gas kinematics around quasars are likely to represent an important source of false positives in radial velocity searches for binary black holes, which typically lack the kind of high-cadence data we analyze here. The long-duration, wide-field, and many-epoch spectroscopic monitoring of SDSS-V BHM-RM provides an excellent opportunity for identifying and characterizing broad emission-line variability, and the inferred nature of the inner gas environment, of luminous quasars.

Spurred by rich, multi-wavelength observations and enabled by new simulations, ranging from cosmological to sub-pc scales, the last decade has seen major theoretical progress in our understanding of the circumgalactic medium. We review key physical processes in the CGM. Our conclusions include: (1) The properties of the CGM depend on a competition between gravity-driven infall and gas cooling. When cooling is slow relative to free fall, the gas is hot (roughly virial temperature) whereas the gas is cold (T~10^4 K) when cooling is rapid. (2) Gas inflows and outflows play crucial roles, as does the cosmological environment. Large-scale structure collimates cold streams and provides angular momentum. Satellite galaxies contribute to the CGM through winds and gas stripping. (3) In multiphase gas, the hot and cold phases continuously exchange mass, energy and momentum. The interaction between turbulent mixing and radiative cooling is critical. A broad spectrum of cold gas structures, going down to sub-pc scales, arises from fragmentation, coagulation, and condensation onto gas clouds. (4) Magnetic fields, thermal conduction and cosmic rays can substantially modify how the cold and hot phases interact, although microphysical uncertainties are presently large. Key open questions for future work include the mutual interplay between small-scale structure and large-scale dynamics, and how the CGM affects the evolution of galaxies.

Direct measurements of cosmic rays have finally entered a precision era. Large particle physics experiments operating in space allowed high-statistic measurements of the cosmic ray energy spectra, of their chemical and isotopic composition, and of the rare antimatter components, in a wide energy range. In this paper, I will review the progress in the field, the recent results, their implications on our understanding on the origin of cosmic rays, the new open questions, the challenges for future experiments of direct detection of cosmic rays.

A growing number of gamma-ray burst (GRB) afterglows is observed at very-high energies (VHE, $\gtrsim 100$ GeV). Yet, our understanding of the mechanism powering the VHE emission remains baffling. We make use of multi-wavelength observations of the afterglow of GRB 180720B, GRB 190114C, and GRB 221009A to investigate whether the bursts exhibiting VHE emission share common features, assuming the standard afterglow model. By requiring that the blastwave should be transparent to $\gamma$-$\gamma$ pair production at the time of observation of the VHE photons and relying on typical prompt emission efficiencies and data in the radio, optical and X-ray bands, we infer for those bursts that the initial energy of the blastwave is $\tilde{E}_{k, \rm{iso}} \gtrsim \mathcal{O}(10^{54})$ erg and the circumburst density is $n_0 \lesssim \mathcal{O}(10^{-1})$ cm$^{-3}$ for a constant circumburst profile [or $A_\star \lesssim \mathcal{O}(10^{-1})$ cm$^{-1}$ for a wind scenario]. Our findings thus suggest that these VHE bursts might be hosted in low-density environments. While these trends are based on a small number of bursts, the Cherenkov Telescope Array has the potential to provide crucial insight in this context by detecting a larger sample of VHE GRBs. In addition, due to the very poor statistics, the non-observation of high-energy neutrinos cannot constrain the properties of these bursts efficiently, unless additional VHE GRBs should be detected at distances closer than $15$ Mpc when IceCube-Gen2 radio will be operational.

GeV and TeV emission from the forward shocks of supernova remnants (SNRs) indicates that they are capable particle accelerators, making them promising sources of Galactic cosmic rays (CRs). However, it remains uncertain whether this $\gamma$-ray emission arises primarily from the decay of neutral pions produced by very high energy hadrons, or from inverse-Compton and/or bremsstrahlung emission from relativistic leptons. By applying a semi-analytic approach to non-linear diffusive shock acceleration (NLDSA) and calculating the particle and photon spectra produced in different astrophysical environments, we parametrize the relative strength of hadronic and leptonic emission. We show that, even if CR acceleration is likely to occur in all SNRs, the observed photon spectra may instead primarily reflect the environment surrounding the SNR, specifically the ambient density and radiation field. We find that the most hadronic-appearing spectra are young and found in environments of high density but low radiation energy density. This study aims to guide the interpretation of current $\gamma$-ray observations and single out the best targets of future campaigns.

Despite extensive search efforts, direct observations of the first (Pop III) stars have not yet succeeded. Theoretical studies have suggested that late Pop III star formation (SF) is still possible in pristine clouds of high-mass galaxies, coexisting with Pop II stars, down to the Epoch of Reionization (EoR). Here we reassess this finding by exploring Pop III SF in eight $50h^{-1} ~ \mathrm{cMpc}$ simulations performed with the hydrodynamical code dustyGadget. We find that Pop III SF ($\sim 10^{-3.4} - 10^{-3.2} ~ \mathrm{M_\odot yr^{-1} cMpc^{-3}}$) is still occurring down to $z \sim 6 - 8$, i.e. well within the reach of deep JWST surveys. At these epochs, $\gtrsim 20 - 30 \%$ of galaxies with $M_\star \gtrsim 3 \times 10^9 ~ \mathrm{M_\odot}$ are found to host Pop III stars, although with a Pop III/Pop II mass fraction $\lesssim 0.1 \%$. Regardless of their mass, Pop\ III hosting galaxies are mainly found on the main sequence, at high SFRs, probably induced by accretion of pristine gas. This scenario is also supported by their increasing SF histories and their preferential location in high-density regions of the cosmic web. Pop\ III stars are found both in the outskirts of metal-enriched regions and in isolated, pristine clouds. In the latter case, their signal may be less contaminated by Pop IIs, although its detectability will strongly depend on the specific line-of-sight to the source, due to the complex morphology of the host galaxy and its highly inhomogeneous dust distribution.

The Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) is an optical interferometric imaging device that aims to offer an alternative to the large space telescope designs of today with reduced size, weight and power consumption. This is achieved through interferometric imaging. State-of-the-art methods for reconstructing images from interferometric measurements adopt proximal optimization techniques, which are computationally expensive and require handcrafted priors. In this work we present two data-driven approaches for reconstructing images from measurements made by the SPIDER instrument. These approaches use deep learning to learn prior information from training data, increasing the reconstruction quality, and significantly reducing the computation time required to recover images by orders of magnitude. Reconstruction time is reduced to ${\sim} 10$ milliseconds, opening up the possibility of real-time imaging with SPIDER for the first time. Furthermore, we show that these methods can also be applied in domains where training data is scarce, such as astronomical imaging, by leveraging transfer learning from domains where plenty of training data are available.

We investigate the first emergence of the so-called cold accretion, the accretion flows deeply penetrating a halo, in the early universe with cosmological N-body/SPH simulations. We study the structure of the accretion flow and its evolution within small halos with $\lesssim 10^8~{\rm M}_\odot$ with sufficiently high spatial resolutions down to $\sim 1 \ {\rm pc}$ scale. While previous studies only follow the evolution for a short period after the primordial cloud collapse, we follow the long-term evolution until the cold accretion first appears, employing the sink particle method. We show that the cold accretion emerges when the halo mass exceeds $\sim 2.2\times 10^7 \ {\rm M}_\odot\left\{\left(1+z\right)/15 \right\}^{-3/2}$, the ${\it minimum}$ halo masses above which the accretion flow penetrates halos. We further continue simulations to study whether the cold accretion provides the dense shock waves, which have been proposed to give birth to supermassive stars (SMSs). We find that the accretion flow eventually hits a compact disc near the halo centre, creating dense shocks over a wide area of the disc surface. The resulting post-shock gas becomes dense and hot enough with its mass comparable to the Jeans mass $M_{\rm J}\sim 10^{4-5} \ {\rm M}_\odot$, a sufficient amount to induce the gravitational collapse, leading to the SMS formation.

With the upcoming plethora of astronomical time-domain datasets and surveys, anomaly detection as a way to discover new types of variable stars and transients has inspired a new wave of research. Yet, the fundamental definition of what constitutes an anomaly and how this depends on the overall properties of the population of light curves studied remains a discussed issue. Building on a previous study focused on Kepler light curves, we present an analysis that uses the Unsupervised Random Forest to search for anomalies in TESS light curves. We provide a catalogue of anomalous light curves, classify them according to their variability characteristics and associate their anomalous nature to any particular evolutionary stage or astrophysical configuration. For anomalies belonging to known classes (e.g. eclipsing binaries), we have investigated which physical parameters drive the anomaly score. We find a combination of unclassified anomalies and objects of a known class with outlying physical configurations, such as rapid pulsators, deep eclipsing binaries of long periods, and irregular light curves due to obscuration in YSOs. Remarkably, we find that the set of anomalous types differ between the Kepler and TESS datasets, indicating that the overall properties of the parent population are an important driver of anomalous behaviour.

We investigate cosmological structure formation in Fuzzy Dark Matter (FDM) with an attractive self-interaction (SI) with numerical simulations. Such a SI would arise if the FDM boson were an ultra-light axion, which has a strong CP symmetry-breaking scale (decay constant). Although weak, the attractive SI may be strong enough to counteract the quantum 'pressure' and alter structure formation. We find in our simulations that the SI can enhance small-scale structure formation, and soliton cores above a critical mass undergo a phase transition, transforming from dilute to dense solitons.

The study of the early phases of star and planet formation is important to understand the physical and chemical history of stellar systems such as our own. In particular, protostars born in rich clusters are prototypes of the young Solar System. In the framework of the Seeds Of Life In Space (SOLIS) large observational project, the aim of the present work is to investigate the origin of the previously inferred high flux of energetic particles in the protocluster FIR4 of the Orion Molecular Cloud 2 (OMC-2), which appears asymmetric within the protocluster itself. Interferometric observations carried out with the IRAM NOEMA interferometer were used to map the silicon monoxide (SiO) emission around the FIR4 protocluster. Complementary archival data from the ALMA interferometer were also employed to help constrain excitation conditions. A physical-chemical model was implemented to characterise the particle acceleration along the protostellar jet candidate, along with a non-LTE analysis of the SiO emission along the jet. The emission morphology of the SiO rotational transitions hints for the first time at the presence of a collimated jet originating very close to the brightest protostar in the cluster, HOPS-108. The NOEMA observations unveiled a possible jet in the OMC-2 FIR4 protocluster propagating towards a previously measured enhanced cosmic-ray ionisation rate. This suggests that energetic particle acceleration by the jet shock close to the protostar might be at the origin of the enhanced cosmic-ray ionisation rate, as confirmed by modelling the protostellar jet.

Dust can play an important role in shaping the X-ray spectra and images of astrophysical sources. In this work we report on the implementation of dust in the ray-tracing platform RefleX. We illustrate the different effects associated to the interaction between X-ray photons and dust grains, such as dust scattering, near-edge X-ray absorption fine structures and shielding. We show how the cross-sections of the photon-gas interaction change depending on the fraction of metals in dust grains (i.e. the dust depletion factor). We compare RefleX simulations to the most widely-used absorption model that includes dust, and show how X-ray spectra are affected by the presence of dust in the absorbing/reprocessing medium for different geometries. We also show how RefleX can be used to reproduce the dust scattering halos observed in Galactic sources, and release the first torus X-ray spectral model that considers dust absorption and scattering (RXTorusD), to reproduce the spectra of active galactic nuclei (AGN). RXTorusD also considers other physical process that are not included in the most widely-used AGN torus models, such as Rayleigh scattering and scattering on molecular gas, which can lead to remarkable differences in the predicted X-ray spectra for the same set of geometrical and physical parameters.

In this paper, we aim to derive high-precision alpha-element abundances using CRIRES high-resolution IR spectra of 72 cool M giants of the inner Galactic bulge. Silicon, magnesium, and calcium abundances were determined by fitting a synthetic spectrum for each star. We also incorporated recent theoretical data into our spectroscopic analysis (i.e. updated K-band line list, better broadening parameter estimation, non-local thermodynamic equilibrium (NLTE) corrections). We compare these inner bulge alpha abundance trends with those of solar neighbourhood stars observed with IGRINS using the same line list and analysis technique; we also compare our sample to APOGEE DR17 abundances for inner bulge stars. We investigate bulge membership using spectro-photometric distances and orbital simulations. We construct a chemical-evolution model that fits our metallicity distribution function (MDF) and our alpha-element trends. Among our 72 stars, we find four that are not bulge members. [Si/Fe] and [Mg/Fe] versus [Fe/H] trends show a typical thick disc alpha-element behaviour, except that we do not see any plateau at supersolar metallicities as seen in other works. The NLTE analysis lowers [Mg/Fe] typically by $\sim$0.1 dex, resulting in a noticeably lower trend of [Mg/Fe] versus [Fe/H]. The derived [Ca/Fe] versus [Fe/H] trend has a larger scatter than those for Si and Mg, but is in excellent agreement with local thin and thick disc trends. With our updated analysis, we constructed one of the most detailed studies of the alpha abundance trends of cool M giants in the inner Galactic bulge. We modelled these abundances by adopting a two-infall chemical-evolution model with two distinct gas-infall episodes with timescales of 0.4 Gyr and 2 Gyr, respectively. Based on a very meticulous spectral analysis, we have constructed detailed and precise chemical abundances of Mg, Si, and Ca for cool M giants.

$\delta$ Orionis is the closest massive multiple stellar system and one of the brightest members of the Orion OB association. The primary (Aa1) is a unique evolved O star. In this work, we applied a two-step disentangling method to a series of spectra in the blue region (430 to 450 nm), and we detected spectral lines of the secondary (Aa2). For the first time, we were able to constrain the orbit of the tertiary (Ab) - to 55 450 d or 152 yr - using variable $\gamma$ velocities and new speckle interferometric measurements, which have been published in the Washington Double Star Catalogue. In addition, the Gaia DR3 parallax of the faint component (Ca+Cb) constrains the distance of the system to (381 $\pm$ 8) pc, which is just in the centre of the Orion OB1b association, at (382 $\pm$ 1) pc. Consequently, we found that the component masses according to the three-body model are 17.8, 8.5, and 8.7 M$_{\odot}$, for Aa1, Aa2, and Ab, respectively, with the uncertainties of the order of $1$ M$_{\odot}$. We used new photometry from the BRITE satellites together with astrometry, radial velocities, eclipse timings, eclipse duration, spectral line profiles, and spectral energy distribution to refine radiative properties. The components, classified as O9.5 II + B2 V + B0 IV, have radii of 13.1, 4.1, and 12.0 R$_{\odot}$, which means that $\delta$ Ori A is a pre-mass-transfer object. The frequency of 0.478 cycles per day, known from the Fourier analysis of the residual light curve and X-ray observations, was identified as the rotation frequency of the tertiary. $\delta$ Ori could be related to other bright stars in Orion, in particular, $\zeta$ Ori, which has a similar architecture, or $\varepsilon$ Ori, which is a single supergiant, and possibly a post-mass-transfer object.

The angle between the rotation and orbital axes of stars in binary systems -- the obliquity -- is an important indicator of how these systems form and evolve but few such measurements exist. We combine the sample of astrometric orbital inclinations from Gaia DR3 with a sample of solar-like oscillators in which rotational inclinations have been measured using asteroseismology. We supplement our sample with one binary whose visual orbit has been determined using speckle interferometry and present the projected spin-orbit alignments in five systems. We find that each system, and the overall sample, is consistent with alignment but there are important caveats. First, the asteroseismic rotational inclinations are fundamentally ambiguous and, second, we can only measure the projected (rather than true) obliquity. If rotational and orbital inclinations are independent and isotropically-distributed, however, the likelihood of drawing our data by chance is less than a few per cent. Though small, our data set argues against uniformly random obliquities in binary systems. We speculate that dozens more measurements could be made using data from NASA's TESS mission, mostly in red giants. ESA's PLATO mission will likely produce hundreds more spin-orbit measurements in systems with main-sequence and subgiant stars.

Recent progress with pulsar timing array experiments, especially from the NANOGrav collaboration indicate that we are on the cusp of detecting significant signals from the inspiral of super-massive black hole binaries (SMBHB). While recent analysis has focused on nearby galaxies as possible sources of the loudest signals, we show that mergers in identified clusters at z~1 can have larger strain amplitudes. We make an estimate comparing the nearby 2MASS redshift survey galaxy sample with the more distant MaDCoWS cluster sample, showing that the latter might be expected to contribute more, and louder, gravitational wave events. Thus the first individual source detections may well be from ultra-massive BH in clusters at z~1, rather than nearby galaxies.

In 2005, the United States Congress passed a bill mandating the detection, tracking, cataloguing and characterization of 90\% of the 140 meter and larger near-Earth objects (NEOs) by 2020. At the deadline $\sim$35\% were detected, tracked and catalogued, but only a small fraction were characterized. At the present rate, it will take 40 years to meet the detection mandate, and there are insufficient global facilities dedicated to NEO characterization to come close to the characterization threshold. The major surveys focus mainly on detection and initial orbit determination, which must be refined in order to fully be tracked and catalogued. Characterization requires observations spanning multiple wavelengths, cadences, and instruments, so it is challenging for observers to acquire the requisite data in a timely manner for planetary defense. Two upcoming surveys will easily meet the 90\% threshold for detection, but each will require separate facilities to tip and queue to refine orbits and characterize new discoveries, and they will provide too many discoveries for ground and space-based assets to keep up with. Here, I argue for a constellation of proliferating small satellites carrying visible and infrared sensors that would offer the needed coverage and flexibility to follow up detections from current and upcoming surveys in a timely manner. Such a constellation would enable NASA to move beyond the detection focused investments and fully meet the 2005 Congressional mandate.

Photon trapping is believed to be an important mechanism in super-Eddington accretion, which greatly reduces the radiative efficiency as photons are swallowed by the central black hole before they can escape from the accretion flow. This effect is interpreted as the radial advection of energy in one-dimensional height-integrated models, such as the slim disc model. However, when multi-dimensional effects are considered, the conventional understanding may no longer hold. In this paper, we study the advective energy transport in super-Eddington accretion, based on a new two-dimensional inflow-outflow solution with radial self-similarity, in which the advective factor is calculated self-consistently by incorporating the calculation of radiative flux, instead of being set as an input parameter. We found that radial advection is actually a heating mechanism in the inflow due to compression, and the energy balance in the inflow is maintained by cooling via radiation and vertical ($\theta$-direction) advection, which transports entropy upwards to be radiated closer to the surface or carried away by the outflow. As a result, less photons are advected inwards and more photons are released from the surface, so that the mean advective factor is smaller and the emergent flux is larger than those predicted by the slim disc model. The radiative efficiency of super-Eddington accretion thus should be larger than that of the slim disc model, which agrees with the results of some recent numerical simulations.

We present the first catalog of supernova remnants (SNRs) in M31 which exhibit diffuse ultraviolet (UV) emission. UV images of M31 were obtained by the Ultraviolet Imaging Telescope (UVIT) on the AstroSat satellite, and the list of SNRs was obtained from X-ray, optical and radio catalogues of SNRs in M31. We used the UVIT images to find SNRs with diffuse emission, omitting those too contaminated with stellar emission. 20 SNRs in M31 were detected with diffuse UV emission. Fluxes in the UVIT F148W, F169M, F172M, N219M and N279N filters are measured for these SNRs. The luminosities are compared to those computed from the spectra of seven known UV-emitting SNRs in the Milky Way, the LMC, and the SMC. We find similar spectral shapes between the known and the M31 UV-emitting SNRs. The spectral shapes and the diffuse nature of the emission are good evidence that the UV emissions are dominated by line emissions, like known SNRs, and the UV is associated with the SNRs. Models are applied to the 6 SNRs with X-ray spectra. The main difference is that the 2 X-ray/UV SNRs are Type Ia and the 4 X-ray/non-UV SNRs are core-collapse or unknown type. A comparison of M31 SNRs in different wavebands shows that most are detected optically, similar to the case for other nearby galaxies. 19 of the 20 UV-emitting SNRs are detected optically, expected because both UV and optical are from forbidden and recombination lines from shock-ionized gas.

We present the star formation histories (SFHs) of early-type dwarf galaxies, dSphs and dEs, in the local universe within z=0.01. The SFHs of early-type dwarf galaxies are characterized by pre-enriched, metal-poor old stellar populations, absence of moderately old stars that have ages of a few Gyr. There are some differences in the SFHs of dSphs and dEs. In particular, dSphs formed old ($\gtrsim10$ Gyr old) metal-poor stars $\sim2$ times more than dEs. The effects of reionization and feedback from supernova explosions are thought to be strong enough to remove the gas left, which prevent moderately old stellar populations in dSphs. In contrast, the ejected gas are not completely removed from dEs and fall back to ignite burst of star formation at a few Gyr after the first period of violent bursts of star formation, showing a suppression of star formation at lookback time $\approx 9.6$ Gyr. The second peak of star formation at lookback time $\approx 4.5$ Gyr in dEs produce moderately old stellar populations. Distinction between dSphs and dEs is useful to examine the SFHS of the early-type dwarfs since the cumulative SFHs are most closely related to their morphology. The stellar mass plays an important role in the SFHs of the early-type dwarfs as a driver of star formation, especially in galaxies with primordial origin.

Irradiated Jovian atmospheres are complex, dynamic, and can undergo temporal variations due to the close proximity of their parent stars. Of the Jovian planets that have been catalogued to date, KELT-9b is the hottest Gas Giant known, with an equilibrium temperature of 4050 K. We probe the temporal variability of transmission spectroscopic signatures from KELT-9b via a set of archival multi-year ground-based transit observations, performed with the TRES facility on the 1.5 m reflector at the Fred Lawrence Whipple Observatory. Our observations confirm past detections of Fe I, Fe II and Mg I over multiple epochs, in addition to excess absorption at H-alpha, which is an indicator for ongoing mass-loss. From our multi-year dataset, the H-alpha light curve consistently deviates from a standard transit, and follows a 'W' shape that is deeper near ingress and egress, and shallower mid-transit. To search for and quantify any seasonal variations that may be present, we parameterise a 'cometary tail' model to fit for the H-alpha transit. We find no detectable variations between the different observed epochs. Though a 'cometary tail' describes the H-alpha flux variations well, we note that such a scenario requires a high density of neutral hydrogen in the n = 2 excited state far beyond the planetary atmosphere. Other scenarios, such as centre-to-limb variations larger than that expected from 1-D atmosphere models, may also contribute to the observed H-alpha transit shape. These multi-epoch observations highlight the capabilities of small telescopes to provide temporal monitoring of the dynamics of exoplanet atmospheres.

Abundance matching studies have shown that the average relationship between galaxy radius and dark matter halo virial radius remains nearly constant over many orders of magnitude in halo mass, and over cosmic time since about $z=3$. In this work, we investigate the predicted relationship between galaxy radius $r_{e}$ and halo virial radius $R_{\rm h}$ in the numerical hydrodynamical simulations Illustris and IllustrisTNG from $z\sim 0$--3, and compare with the results from the abundance matching studies. We find that Illustris predicts much higher $r_e/R_{\rm h}$ values than the constraints obtained by abundance matching, at all redshifts, as well as a stronger dependence on halo mass. In contrast, IllustrisTNG shows very good agreement with the abundance matching constraints. In addition, at high redshift it predicts a strong dependence of $r_e/R_{\rm h}$ on halo mass on mass scales below those that are probed by existing observations. We present the predicted $r_e/R_{\rm h}$ relations from Illustris and IllustrisTNG for galaxies divided into star-forming and quiescent samples, and quantify the scatter in $r_e/R_{\rm h}$ for both simulations. Further, we investigate whether this scatter arises from the dispersion in halo spin parameter and find no significant correlation between $r_e/R_{\rm h}$ and halo spin. We investigate the paths in $r_e/R_{\rm h}$ traced by individual haloes over cosmic time, and find that most haloes oscillate around the median $r_e/R_{\rm h}$ relation over their formation history.

Brown dwarfs with well-measured masses, ages and luminosities provide direct benchmark tests of substellar formation and evolutionary models. We report the first results from a direct imaging survey aiming to find and characterize substellar companions to nearby accelerating stars with the assistance of the Hipparcos-Gaia Catalog of Accelerations (HGCA). In this paper, we present a joint high-contrast imaging and astrometric discovery of a substellar companion to HD 176535 A, a K3.5V main-sequence star aged approximately $3.59_{-1.15}^{+0.87}$ Gyrs at a distance of $36.99 \pm 0.03$ pc. In advance of our high-contrast imaging observations, we combined precision HARPS RVs and HGCA astrometry to predict the potential companion's location and mass. We thereafter acquired two nights of KeckAO/NIRC2 direct imaging observations in the $L'$ band, which revealed a companion with a contrast of $\Delta L'_p = 9.20\pm0.06$ mag at a projected separation of $\approx$0.$\!\!''35$ ($\approx$13 AU) from the host star. We revise our orbital fit by incorporating our dual-epoch relative astrometry using the open-source MCMC orbit fitting code $\tt orvara$. HD 176535 B is a new benchmark dwarf useful for constraining the evolutionary and atmospheric models of high-mass brown dwarfs. We found a luminosity of $\rm log(L_{bol}/L_{\odot}) = -5.26\pm0.06$ and a model-dependent effective temperature of $980 \pm 35$ K for HD 176535 B. Our dynamical mass suggests that some substellar evolutionary models may be underestimating luminosity for high-mass T dwarfs. Given its angular separation and luminosity, HD 176535 B would make a promising candidate for Aperture Masking Interferometry with JWST and GRAVITY/KPIC, and further spectroscopic characterization with instruments like the CHARIS/SCExAO/Subaru integral field spectrograph.

In this work, we studied the distribution of lithium abundances in giants as a function of stellar mass. We used a sample of 1240 giants common among Kepler photometric and LAMOST medium resolution (R $\approx$ 7500) spectroscopic survey fields. The asteroseismic $\Delta$P - $\Delta \nu$ diagram is used to define core He-burning red clump giants and red giant branch stars with inert He-core. Li abundances have been derived using spectral synthesis for the entire sample stars. Directly measured values of asteroseismic parameters $\Delta$P(or $\Delta \Pi_1$) and $\Delta \nu$ are either taken from the literature or measured in this study. Of the 777 identified red clump giants, we found 668 low mass ($\leq$ 2~M$_{\odot}$) primary red clump giants and 109 high mass ($>$ 2~M$_{\odot}$) secondary red clump giants. Observed Li abundances in secondary red clump giants agree with the theoretical model predictions. The lack of Li-rich giants among secondary red clump giants and the presence of Li-rich, including super Li-rich giants, among primary red clump stars reinforces the idea that Helium-flash holds the key for Li enrichment among low-mass giants. The results will further constrain theoretical models searching for a physical mechanism for Li enhancement among low-mass red clump giants. Results also serve as observational evidence that only giants with mass less than $\approx$ 2~M$_{\odot}$ develop degenerate He-core and undergo He-flash.

Black hole X-ray binary systems (BHBs) contain a close companion star accreting onto a stellar-mass black hole. A typical BHB undergoes transient outbursts during which it exhibits a sequence of long-lived spectral states, each of which is relatively stable. GRS 1915+105 is a unique BHB that exhibits an unequaled number and variety of distinct variability patterns in X-rays. Many of these patterns contain unusual behaviour not seen in other sources. These variability patterns have been sorted into different classes based on count rate and color characteristics by Belloni et al (2000). In order to remove human decision-making from the pattern-recognition process, we employ an unsupervised machine learning algorithm called an auto-encoder to learn what classifications are naturally distinct by allowing the algorithm to cluster observations. We focus on observations taken by the Rossi X-ray Timing Explorer's Proportional Counter Array. We find that the auto-encoder closely groups observations together that are classified as similar under the Belloni et al (2000) system, but that there is reasonable grounds for defining each class as made up of components from 3 groups of distinct behaviour.

We establish, in the framework of the theory of nested figures, the expressions for the gravitational moments $J_{2n}$ of a systems made of ${\cal L}$ homogeneous layers separated by spheroidal surfaces and in relative rotational motion. We then discuss how to solve the inverse problem, which consists in finding the equilibrium configurations (i.e. internal structures) that reproduce ``exactly'' a set of observables, namely the equatorial radius, the total mass, the shape and the first gravitational moments. Two coefficients $J_{2n}$ being constrained per surface, ${\cal L}=1+\frac{n}{2}$ layers ($n$ even) are required to fix $J_2$ to $J_{2n}$. As shown, this problem already suffers from a severe degeneracy, inherent in the fact that two spheroidal surfaces in the system confocal with each other leave unchanged all the moments. The complexity, which increases with the number of layers involved, can be reduced by considering the rotation rate of each layer. Jupiter is used as a test-bed to illustrate the method, concretely for ${\cal L}=2,3$ and $4$. For this planet, the number of possible internal structures is infinite for ${\cal L} > 2$. Intermediate layers can have smaller or larger oblateness, and can rotate slower or faster than the surroundings. Configurations with large and massive cores are always present. Low-mass cores (of the order a few Earth masses) are predicted for ${\cal L} \ge 4$. The results are in good agreement with the numerical solutions obtained from the Self-Consistent-Field method.

We present a novel method for reconstructing weak lensing mass or convergence maps as a probe to study non-Gaussianities in the cosmic density field. While previous surveys have relied on a flat-sky approximation, the forthcoming stage IV survey will cover such large areas with a large field of view (FOV) to motivate mass reconstruction on the sphere. Here, we present an improved Kaiser-Squires (KS+) mass inversion method using a HEALPix pixelisation of the sphere while controlling systematic effects. As in the KS+ methodology, the convergence maps were reconstructed without noise regularisation to preserve the Information content and allow for non-Gaussain studies. The results of this new method were compared with those of the Kaiser-Squires (KS) estimator implemented on the curved sky using high-resolution realistic N-body simulations. The quality of the method was evaluated by estimating the two-point correlation functions, third- and fourth-order moments, and peak counts of the reconstructed convergence maps. The effects of masking, sampling, and noise were tested. We also examined the systematic errors introduced by the flat-sky approximation. We show that the improved Kaiser-Squires on the sphere (SKS+) method systematically improves inferred correlation errors by 10 times and provide on average a 20-30 % better maximum signal-to-noise peak estimation compared to Kaiser-Squires on the sphere (SKS). We also show that the SKS+ method is nearly unbiased and reduces errors by a factor of about 2 and 4 in the third and fourth-order moments, respectively. Finally, we show how the reconstruction of the convergence field directly on the celestial sphere eliminates the projection effects and allows the exclusion or consideration of a specific region of the sphere in the processing.

New results on the radio-quiet type 2 quasar known as the Teacup galaxy (SDSSJ1430+1339) based on the long-slit and 3D spectroscopic data obtained at the Russian 6-m telescope are presented. The ionized gas giant nebula extending up to r=56 kpc in the [O III] emission line was mapped with the scanning Fabry-Perot interferometer. The direct estimation of the emission line ratios confirmed that the giant nebula is ionized by the AGN. Stars in the inner r<5 kpc are significantly younger than the outer host galaxy and have a solar metallicity. The central starburst age (~1 Gyr) agrees with possible ages for the galactic merger events and the previous episode of the quasar outflow produced two symmetric arcs visible in the [O III[ emission at the distances r=50-55 kpc. The ionized gas velocity field can be fitted by the model of a circular rotating disk significantly inclined or even polar to the stellar host galaxy.

Context: Young massive star clusters (YMCs) have come increasingly into the focus of discussions on the origin of galactic cosmic rays (CRs). The proposition of CR acceleration inside superbubbles (SBs) blown by the strong winds of these clusters avoids issues faced by the standard paradigm of acceleration at supernova remnant shocks. Aims: We provide an interpretation of the latest TeV $\gamma$-ray observations of the region around the YMC Westerlund 1 taken with the High Energy Stereoscopic System (H.E.S.S.) in terms of diffusive shock acceleration at the cluster wind termination shock, taking into account the spectrum and morphology of the emission. As Westerlund 1 is a prototypical example of a YMC, such a study is relevant to the general question about the role of YMCs for the Galactic CR population. Methods: We generate model $\gamma$-ray spectra, characterise particle propagation inside the SB based on the advection, diffusion, and cooling timescales, and constrain key parameters of the system. We consider hadronic emission from proton-proton interaction and subsequent pion decay and leptonic emission from inverse Compton scattering on all relevant photon fields, including the CMB, diffuse and dust-scattered starlight, and the photon field of Westerlund 1 itself. The effect of the magnetic field on cooling and propagation is discussed. Klein-Nishina effects are found to be important in determining the spectral evolution of the electron population. Results: A leptonic origin of the bulk of the observed $\gamma$-rays is preferable. The model is energetically plausible, consistent with the presence of a strong shock, and allows for the observed energy-independent morphology. The hadronic model faces two main issues: confinement of particles to the emission region and an unrealistic energy requirement.

A key feature of the Galilean satellite system is its monotonic decrease in bulk density with distance from Jupiter, indicating an ice mass fraction that is zero in the innermost moon Io, and about half in the outer moons Ganymede and Callisto. Jupiter formation models, and perhaps the Juno spacecraft water measurements, are consistent with the possibility that the Jovian system may have formed, at least partly, from ice-poor material. And yet, models of the formation of the Galilean satellites usually assume abundant water ice in the system. Here, we investigate the possibility that the Jovian circumplanetary disk was populated with ice-depleted chondritic minerals, including phyllosilicates. We show that the dehydration of such particles and the outward diffusion of the released water vapor allow condensation of significant amounts of ice in the formation region of Ganymede and Callisto in the Jovian circumplanetary disk. Our model predicts that Europa, Ganymede and Callisto should have accreted little if any volatiles other than water ice, in contrast to the comet-like composition of Saturn's moon Enceladus. This mechanism allows for the presence of ice-rich moons in water-depleted formation environments around exoplanets as well.

We report here on the results of the analysis of Chandra, XMM-Newton and NuSTAR recent observations of the Supergiant Fast X-ray Transient XTEJ1739-302. The source was caught in a low X-ray luminosity state, from a few $10^{31}$ to $10^{34}$ erg/s (0.5-10 keV). In particular, a very low X-ray luminosity was captured during an XMM-Newton observation performed in October 2022, at a few $10^{31}$ erg/s (0.5-10 keV), never observed before in XTEJ1739-302. The XMM-Newton spectrum could be well fitted either by an absorbed, steep power law model (photon index of 3.5) or by a collisionally-ionized diffuse gas with a temperature of 0.7 keV, very likely produced by shocks in the supergiant donor wind. These observations covered different orbital phases, but all appear compatible with the low luminosity level expected from the orbital INTEGRAL light curve. The absorbing column density is variable in the range $10^{22}-10^{23}$ cm$^{-2}$. A broad-band X-ray spectrum could be investigated at $10^{34}$ erg/s (0.5-30 keV) for the first time in XTEJ1739-302 with not simultaneous (but at similar orbital phases) Chandra and NuSTAR data, showing a power law spectral shape with a photon index of about 2.2 and an absorbing column density of $\sim$$10^{23}$ cm$^{-2}$. Remarkably, owing to the XMM-Newton observation, the amplitude of the X-ray variability has increased to five orders of magnitude, making XTEJ1739-302 one of the most extreme SFXTs.

We report low-frequency radio observations of the 2021 outburst of the recurrent nova RS Ophiuchi. These observations include the lowest frequency observations of this system to date. Detailed light curves are obtained by MeerKAT at 0.82 and 1.28 GHz and LOFAR at 54 and 154 MHz. These low-frequency detections allow us to put stringent constraints on the brightness temperature that clearly favour a non-thermal emission mechanism. The radio emission is interpreted and modelled as synchrotron emission from the shock interaction between the nova ejecta and the circumbinary medium. The light curve shows a plateauing behaviour after the first peak, which can be explained by either a non-uniform density of the circumbinary medium or a second emission component. Allowing for a second component in the light curve modelling captures the steep decay at late times. Furthermore, extrapolating this model to 15 years after the outburst shows that the radio emission might not fully disappear between outbursts. Further modelling of the light curves indicates a red giant mass loss rate of $\sim 5 \cdot 10^{-8}~{\rm M_\odot~yr^{-1}}$. The spectrum cannot be modelled in detail at this stage, as there are likely at least four emission components. Radio emission from stellar wind or synchrotron jets are ruled out as the possible origin of the radio emission. Finally, we suggest a strategy for future observations that would advance our understanding of the physical properties of RS Oph.

Recent Herschel observations of nearby clouds have shown that filamentary structures are ubiquitous and that most prestellar cores form in filaments. Probing the density ($n$) and velocity ($V$) structure of filaments is crucial for the understanding of the star formation process. To characterize both the $n$ and the $V$ field of a fragmenting filament, we mapped NGC2024. 13CO, C18O, and H13CO+ trace the filament seen in the $N_{H_2}$ data. The radial profile from the $N_{H_2}$ data shows $D_{HP}$~0.081 pc, which is similar to the Herschel findings. The $D_{HP}$ from 13CO and C18O are broader, while the $D_{HP}$ from H13CO+ is narrower, than $D_{HP}$ from Herschel. These results suggest that 13CO and C18O trace only the outer part of the filament and H13CO+ only the inner part. The H13CO+ $V_{centroid}$ map reveals $V$ gradients along both filament axis, as well as $V$ oscillations with a period $\lambda$~0.2 pc along the major axis. Comparison between the $V$ and the $n$ distribution shows a tentative $\lambda$/4 shift in H13CO+ or C18O. This $\lambda$/4 shift is not simultaneously observed for all cores in any single tracer but is tentatively seen in either H13CO+ or C18O. We produced a toy model taking into account a transverse $V$ gradient, a longitudinal $V$ gradient, and a longitudinal oscillation mode caused by fragmentation. Examination of synthetic data shows that the oscillation component produces an oscillation pattern in the velocity structure function (VSF) of the model. The H13CO+ VSF shows an oscillation pattern, suggesting that our observations are partly tracing core-forming motions and fragmentation. We also found that the mean $M_{core}$ corresponds to the effective $M_{BE}$ in the filament. This is consistent with a scenario in which higher-mass cores form in higher line-mass filaments.

The Hubble constant ($H_0$) tension is one of the major open problems in modern cosmology. This tension is the discrepancy, ranging from 4 to 6 $\sigma$, between the $H_0$ value estimated locally with the combination of Supernovae Ia (SNe Ia) + Cepheids and the cosmological $H_0$ obtained through the study of the Cosmic Microwave Background (CMB) radiation. The approaches adopted in Dainotti et al. 2021 (ApJ) and Dainotti et al. 2022 (Galaxies) are introduced. Through a binning division of the Pantheon sample of SNe Ia (Scolnic et al. 2018), the value of $H_0$ has been estimated in each of the redshift-ordered bins and fitted with a function lowering with the redshift. The results show a decreasing trend of $H_0$ with redshift. If this is not due to astrophysical biases or residual redshift evolution of the SNe Ia parameters, it can be explained in light of modified gravity theories, e.g., the $f(R)$ scenarios. We also briefly describe the possible impact of high-$z$ probes on the Hubble constant tension, such as Gamma-ray bursts (GRBs) and Quasars (QSOs), reported in Dainotti et al. 2022 (Galaxies) and Lenart et al. 2022 (ApJ), respectively.

A naive Bayes classifier for identifying Class II YSOs has been constructed and applied to a region of the Northern Galactic Plane containing 8 million sources with good quality Gaia EDR3 parallaxes. The classifier uses the five features: Gaia $G$-band variability, WISE mid-infrared excess, UKIDSS and 2MASS near-infrared excess, IGAPS H$\alpha$ excess and overluminosity with respect to the main sequence. A list of candidate Class II YSOs is obtained by choosing a posterior threshold appropriate to the task at hand, balancing the competing demands of completeness and purity. At a threshold posterior greater than 0.5 our classifier identifies 6504 candidate Class II YSOs. At this threshold we find a false positive rate around 0.02 per cent and a true positive rate of approximately 87 per cent for identifying Class II YSOs. The ROC curve rises rapidly to almost one with an area under the curve around 0.998 or better, indicating the classifier is efficient at identifying candidate Class II YSOs. Our map of these candidates shows what are potentially three previously undiscovered clusters or associations. When comparing our results to published catalogues from other young star classifiers, we find between one quarter and three quarters of high probability candidates are unique to each classifier, telling us no single classifier is finding all young stars.

We have applied the method of star counts with Wolf diagrams to determine the interstellar extinction in five Galactic cirri in Sloan Digital Sky Survey (SDSS) Stripe 82. For this purpose, we have used the photometry of stars in the GALEX NUV filter and the photometry of red dwarfs in five SDSS bands and four SkyMapper Southern Sky Survey DR2 bands. We have identified the cirri as sky regions with an enhanced infrared emission from the Schlegel+1998 map. The extinction in them has been calculated relative to the nearby comparison regions with a reduced emission. The results for different filters agree well, giving the range of distances and the extinction law for each cirrus. The distances in the range 140--415 pc found are consistent with the 3D reddening maps. In the range between the $B$ and $V$ filters the extinctions found are consistent with the estimates from Schlegel+1998 for the Cardelli+1989 extinction law with $R_\mathrm{V}=3.1$. However, the extinctions found for all of the filters are best described not by the Cardelli+1989 extinction law with some $R_\mathrm{V}=3.1$, but by the inverse proportionality of the extinction and wavelength with its own coefficient for each cirrus. In one of the cirri our results suggest a very slight decrease in extinction with wavelength, i.e., a large contribution of gray extinction. In the remaining cirri a manifestation of gray extinction is not ruled out either. This is consistent with the previous measurements of the extinction law far from the Galactic midplane.

We present new {\em Hubble Space Telescope} WFC3/IR medium-band photometry of the compact elliptical galaxy M32, chemically resolving its thermally pulsating asymptotic giant branch stars. We find 2829 M-type stars and 57 C stars. The carbon stars are likely contaminants from M31. If carbon stars are present in M32 they are so in very low numbers. The uncorrected C/M ratio is 0.020 $\pm$ 0.003; this drops to less than 0.007 after taking into account contamination from M31. As the mean metallicity of M32 is just below solar, this low ratio of C to M stars is unlikely due to a metallicity ceiling for the formation of carbon stars. Instead, the age of the AGB population is likely to be the primary factor. The ratio of AGB to RGB stars in M32 is similar to that of the inner disc of M31 which contain stars that formed 1.5--4 Gyr ago. If the M32 population is at the older end of this age then its lack of C-stars may be consistent with a narrow mass range for carbon star formation predicted by some stellar evolution models. Applying our chemical classifications to the dusty variable stars identified with {\em Spitzer}, we find that the x-AGB candidates identified with {\em Spitzer} are predominately M-type stars. This substantially increases the lower limit to the cumulative dust-production rate in M32 to $>$ 1.97 $\times 10^{-5}$ ${\rm M}_{\odot} \, {\rm yr}^{-1}$.

The stellar activity of M dwarfs is the main limitation for discovering and characterizing exoplanets orbiting them since it induces quasi-periodic RV variations. We aim to characterize the magnetic field and stellar activity of the early, moderately active, M dwarf Gl205 in the optical and nIR domains. We obtained high-precision quasi-simultaneous spectra in the optical and nIR with the SOPHIE spectrograph and SPIRou spectropolarimeter between 2019 and 2022. We computed the RVs from both instruments and the SPIRou Stokes V profiles. We used ZDI to map the large-scale magnetic field over the time span of the observations. We studied the temporal behavior of optical and nIR RVs and activity indicators with the Lomb-Scargle periodogram and a quasi-periodic GP regression. In the nIR, we studied the equivalent width of Al I, Ti I, K I, Fe I, and He I. We modeled the activity-induced RV jitter using a multi-dimensional GP regression with activity indicators as ancillary time series. The optical and nIR RVs have similar scatter but nIR shows a more complex temporal evolution. We observe an evolution of the magnetic field topology from a poloidal dipolar field in 2019 to a dominantly toroidal field in 2022. We measured a stellar rotation period of Prot=34.4$\pm$0.5 d in the longitudinal magnetic field. Using ZDI we measure the amount of latitudinal differential rotation (DR) shearing the stellar surface yielding rotation periods of Peq=32.0$\pm$1.8 d at the stellar equator and Ppol=45.5$\pm$0.3 d at the poles. We observed inconsistencies in the activity indicators' periodicities that could be explained by these DR values. The multi-dimensional GP modeling yields an RMS of the RV residuals down to the noise level of 3 m/s for both instruments, using as ancillary time series H$\alpha$ and the BIS in the optical, and the FWHM in the nIR.

The Isaac Newton Group of Telescopes is completing a strategic change for the scientific use of its two telescopes, the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope (INT). After more than 30 years operating as multi-purpose telescopes, the telescopes will soon complete their shift to nearly-single instrument operation dominated by large surveys. At the WHT, the WEAVE multi-fibre spectrograph is being commissioned in late 2022. Science surveys are expected to launch in 2023. 30% of the available time will be offered in open time. For the INT, construction of HARPS-3, a high-resolution ultra-stable spectrograph for extra-solar planet studies, is underway, with deployment planned for late 2024. The INT itself is being modernised and will operate as a robotic telescope. An average of 40% of the time will be offered as open time. The ING will maintain its student programme. Plans call for moving student work from the INT to the WHT once the INT starts operating robotically.

For the past decade, SALT2 has been the most common model used to fit Type Ia supernova (SN Ia) light curves for dark energy analyses. Recently, the SALT3 model was released, which upgraded a number of model features but has not yet been used for measurements of dark energy. Here, we evaluate the impact of switching from SALT2 to SALT3 for a SN cosmology analysis. We train SALT2 and SALT3 on an identical training sample of 1083 well-calibrated Type Ia supernovae, ensuring that any differences found come from the underlying model framework. We publicly release the results of this training (the SALT "surfaces"). We then run a cosmology analysis on the public Dark Energy Survey 3-Year Supernova data sample (DES-SN3YR), and on realistic simulations of those data. We provide the first estimate of the SN+CMB systematic uncertainty arising from the choice of SALT model framework (i.e. SALT2 versus SALT3), $\Delta w = +0.001 \pm 0.005$ -- a negligible effect at the current level of dark energy analyses. We also find that the updated surfaces are less sensitive to photometric calibration uncertainties than previous SALT2 surfaces, with the average spectral energy density dispersion reduced by a factor of two over optical wavelengths. This offers an opportunity to reduce the contribution of calibration errors to SN cosmology uncertainty budgets.

Compression in giant molecular cloud (GMC) collisions is a promising mechanism to trigger formation of massive star clusters and OB associations. We simulate colliding and non-colliding magnetised GMCs and examine the properties of prestellar cores, selected from projected mass surface density maps, including after synthetic {\it ALMA} observations. We then examine core properties, including mass, size, density, velocity, velocity dispersion, temperature and magnetic field strength. After four Myr, $\sim1,000$ cores have formed in the GMC collision and the high-mass end of the core mass function (CMF) can be fit by a power law $dN/d{\rm{log}}M\propto{M}^{-\alpha}$ with $\alpha\simeq0.7$, i.e., relatively top-heavy compared to a Salpeter mass function. Depending on how cores are identified, a break in the power law can appear around a few $\times10\:M_\odot$. The non-colliding GMCs form fewer cores with a CMF with $\alpha\simeq0.8$ to 1.2, i.e., closer to the Salpeter index. We compare the properties of these CMFs to those of several observed samples of cores. Considering other properties, cores formed from colliding clouds are typically warmer, have more disturbed internal kinematics and are more likely to be gravitational unbound, than cores formed from non-colliding GMCs. The dynamical state of the protocluster of cores formed in the GMC-GMC collision is intrinsically subvirial, but can appear to be supervirial if the total mass measurement is affected by observations that miss mass on large scales or at low densities.

Recent integral-field spectroscopy observations have revealed that thick- and thin-disk star-formation histories are regulated by the interplay of internal and external processes. We analyze stellar-population properties of 24 spiral galaxies from the AURIGA zoom-in cosmological simulations, to offer a more in-depth interpretation of observable properties. We present edge-on maps of stellar age, metallicity and [Mg/Fe] abundance, and we extract the star-formation and chemical-evolution histories of thin and thick disks. Both show signs of the interplay between internal chemical enrichment and gas and star accretion. Thick disks show particularly complex stellar populations, including an in-situ component, formed from both slowly enriched and accreted more pristine gas, and an additional significant fraction of ex-situ stars.

Early-time light curves/spectra of some hydrogen-rich supernovae (SNe) give firm evidence on the existence of confined, dense circumstellar matter (CSM) surrounding dying massive stars. We numerically and analytically study radiative acceleration of CSM in such systems, where the radiation is mainly powered by the interaction between the SN ejecta and the CSM. We find that the acceleration of the ambient CSM is larger for massive and compact CSM, with velocities reaching up to $\sim 10^3\ {\rm km\ s^{-1}}$ for a CSM of order $0.1\ M_\odot$ confined within $\sim 10^{15}$ cm. We show that the dependence of the acceleration on the CSM density helps us explain the diversity of the CSM velocity inferred from the early spectra of some Type II SNe. For explosions in even denser CSM, radiative acceleration can affect the dissipation of strong collisionless shocks formed after the shock breakout, which would affect early non-thermal emission expected from particle acceleration.

We present the timing and spectral studies of the Be/X-ray binary XTE J1946+274 during its 2018 and 2021 giant outbursts using observations with the SXT and the LAXPC instruments on the AstroSat satellite. Unlike the 1998 and 2010 outbursts, where a giant outburst was followed by several low intensity periodic outbursts, the 2018 and 2021 outbursts were single outbursts. The X-ray pulsations are detected over a broad energy band covering 0.5-80 keV from the compact object. We construct the spin evolution history of the pulsar over two decades and find that the pulsar spins-up during the outbursts but switches to spin-down state in the quiescent periods between the outbursts. Energy resolved pulse profiles generated in several bands in 0.5-80 keV show that the pulse shape varies with the energy. The energy spectrum of the pulsar is determined for the 2018 and 2021 outbursts. The best fit spectral models require presence of Cyclotron Resonant Scattering Feature (CRSF) at about 43 keV in the energy spectra of both the outbursts. We find indication of possible reversal in the correlation between the cyclotron line energy and luminosity which needs to be ascertained from future observations. Using the best fit spectra the X-ray luminosity of XTE J1946+274 is inferred to be $2.7 \times 10^{37}$ erg s$^{-1}$ for the 2018 observations and $2.3 \times 10^{37}$ erg s$^{-1}$ for the 2021 observations. We discuss possible mechanisms which can drive outbursts in this transient Be X-ray binary.

The JWST is revolutionizing the study of high-redshift galaxies by providing for the first time a high-sensitivity view of the early Universe at infrared wavelengths, both with its Near Infrared Camera (NIRCam) and Mid Infrared Instrument (MIRI). In this paper, we make use of medium and broad-band NIRCam imaging, as well as ultra-deep MIRI 5.6 microns imaging, in the Hubble eXtreme Deep Field (XDF) to identify prominent line emitters at z ~ 7-8. Out of a total of 58 galaxies at z ~ 7-8, we find 18 robust candidates (~31%) for prominent (Hb + [OIII]) emitters, based on their enhanced fluxes in the F430M and F444W filters, with rest-frame EW(Hb + [OIII]) ~ 87 - 2100 A. Among these emitters, 16 lie on the MIRI coverage area and 12 show a clear flux excess at 5.6 microns, indicating the simultaneous presence of a prominent Ha emission line with rest-frame EW(Ha) ~ 200 - 3000 A. This is the first time that Ha emission can be detected in individual galaxies at z>7. The Ha line, when present, allows us to separate the contributions of the Hb and [OIII] emission lines to the (Hb + [OIII]) complex and derive Ha-based star formation rates (SFRs). We find that in some cases [OIII]/Hb > 1, suggesting low metallicities, but a few have [OIII]/Hb < 1, so the NIRCam flux excess is mainly driven by Hb. The vast majority of prominent line emitters are very young starbursts or galaxies on their way to/from the starburst cloud. They make for a cosmic SFR density log10(SFRD_Ha / Msun yr^-1 Mpc^-3) ~ 2.35, which is about a third of the total value at z ~ 7-8. Therefore, the strong Ha emitters likely had an important role in reionization.

In astrophysics, several key questions in the hard X soft Gamma-ray range (above 100 keV) require sensitivity and angular resolution that are hardly achievable with current technologies. Therefore, a new kind of instrument able to focus hard X and gamma-rays is essential. Broad band Laue lenses seem to be the only solution to fulfil these requirements, significantly improving the sensitivity and angular resolution of the X and gamma-ray telescopes. This type of high-energy optics will require highly performing focal plane detectors in terms of detection efficiency, spatial resolution, and spectroscopy. This paper presents the results obtained in the project 'Technological Readiness Increase for Laue Lenses (TRILL)' framework using a Caliste-HD detector module. This detector is a pixel spectrometer developed at CEA (Commissariat a Energie Atomique, Saclay, France). It is used to acquire spectroscopic images of the focal spot produced by Laue Lens bent crystals under a hard X-ray beam at the LARIX facility (University of Ferrara, Italy).

Exomoons are a missing piece of exoplanetary science. Recently, two promising candidates were proposed, Kepler-1625 b-I and Kepler-1708 b-I. While the latter still lacks a dynamical analysis of its stability, Kepler-1625 b-I has already been the subject of several studies regarding its stability and origin. Moreover, previous works have shown that this satellite system could harbour at least two stable massive moons. Motivated by these results, we explored the stability of co-orbital exomoons using the candidates Kepler-1625 b-I and Kepler-1708 b-I as case studies. To do so, we performed numerical simulations of systems composed of the star, planet, and the co-orbital pair formed by the proposed candidates and another massive body. For the additional satellite, we varied its mass and size from a Mars-like to the case where both satellites have the same physical characteristics. We investigated the co-orbital region around the Lagrangian equilibrium point $L_4$ of the system, setting the orbital separation between the satellites from $\theta_{min} = 30^{\circ}$ to $\theta_{max} = 90^{\circ}$. Our results show that stability islands are possible in the co-orbital region of Kepler-1708 b-I as a function of the co-orbital companion's mass and angular separation. Also, we identified that resonances of librational frequencies, especially the 2:1 resonance, can constrain the mass of the co-orbital companion. On the other hand, we found that the proximity between the host planet and the star makes the co-orbital region around Kepler-1625 b-I unstable for a massive companion. Finally, we provide TTV profiles for a planet orbited by co-orbital exomoons.

We study the reconstructed deceleration parameter splitting the data in different redshift bins, fitting both a cosmographic luminosity distance and also assuming a flat $\Lambda$CDM model, using the Pantheon+ sample of type Ia supernova data (SNIA). We observe tensions $\sim 2\sigma-3\sigma$ for different redshift and distance indicators if the full sample is used. However, those tensions disappear when the SNIA at $z<0.008$ are removed. If the data is splitted in 2 hemispheres according to our movement w.r.t CMB, a strange $3.8 \sigma$ tension appears in one of the samples between particular redshift bins. Finally, considering posterior distribution as Gaussian, general linear model prefers a positive slope for $q_0$ across redshift bins opposed to a zero slope expected in a $\Lambda$CDM universe. We discuss possible explanations for our results and the influence of lowest redshift SNIA data in cosmological analysis.

We consider the dynamics of and emission from growing superbubbles in a stratified interstellar gaseous disc driven by energy release from supernovae explosions in stellar clusters with {masses $M_{cl}= 10^5-1.6\times 10^6~M_\odot$}. Supernovae are spread randomly within a sphere of $r_c=60$ pc, and inject energy episodically with a specific rate $1/130~M_\odot^{-1}$ proportional to the star formation rate (SFR) in the cluster. Models are run for several values of SFR in the range $0.01$ to $0.1~M_\odot$ yr$^{-1}$, with the corresponding average surface energy input rate $\sim 0.04-0.4$ erg cm$^{-2}$ s$^{-1}$. We find that the discrete energy injection by isolated SNe are more efficient in blowing superbubbles: asymptotically they reach heights of up to 3 to 16 kpc for $M_{cl}=10^5-1.6\times 10^5~M_\odot$, correspondingly, and stay filled with a hot and dilute plasma for at least 30 Myr. During this time they emit X-ray, H$\alpha$ and dust infrared emission. X-ray liminosities $L_X\propto {\rm SFR}^{3/5}$ that we derive here are consistent with observations in star-forming galaxies. Even though dust particles of small sizes $a\leq 0.03~\mu$m are sputtered in the interior of bubbles, larger grains still contribute considerably ensuring the bubble luminosity $L_{\rm IR}/{\rm SFR}\sim 5\times 10^7 L_\odot M_\odot^{-1} ~{\rm yr}$. It is shown that the origin of the North Polar Spur in the Milky Way can be connected with activity of a cluster with the stellar mass of $\sim 10^5~M_\odot$ and the ${\rm SFR}\sim 0.1~M_\odot$ yr$^{-1}$ some 25--30 Myr ago. Extended luminous haloes observed in edge-on galaxies (NGC 891 as an example) can be maintained by disc spread stellar clusters of smaller masses $M_\ast \simlt 10^5~M_\odot$.

High resolution cosmic microwave background (CMB) experiments have allowed us to precisely measure the CMB temperature power spectrum down to very small scales (multipole $\ell \sim 3000$). Such measurements at multiple frequencies enable separating the primary CMB anisotropies with other signals like CMB lensing, thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ), and cosmic infrared background (CIB). In this paper, we explore another signal of interest at these frequencies that should be present in the CMB maps: extragalactic CO molecular rotational line emissions, which are the most widely used tracers of molecular gas in the line intensity mapping experiments. Using the SIDES simulations adopted for top hat bandpasses at 150 and 220 GHz, we show that the cross-correlation of the CIB with CO lines has a contribution similar to the CIB-tSZ correlation and the kSZ power, thereby contributing a non-negligible amount to the total power at these scales. This signal, therefore, may significantly impact the recently reported $\geq 3\sigma$ detection of the kSZ power spectrum from the South Pole Telescope (SPT) collaboration, as the contribution of the CO lines is not considered in such analyses. Our results also provide a new way of measuring the CO power spectrum in cross-correlation with the CIB. Finally, these results show that the CO emissions present in the CMB maps will have to be accounted for in all the CMB auto-power spectrum and cross-correlation studies involving a LSS tracer.

It has been recently pointed out that nonlinear effects are necessary to model the ringdown stage of the gravitational waveform produced by the merger of two black holes giving rise to a remnant Kerr black hole. We show that this nonlinear behaviour is explained, both on the qualitative and quantitative level, by near-horizon symmetries of the Kerr black hole within the Kerr/CFT correspondence.

We further investigate the dark energy model based on the Finsler geometry inspired osculating Barthel-Kropina cosmology. The Barthel-Kropina cosmological approach is based on the introduction of a Barthel connection in an osculating Finsler geometry, with the connection having the property that it is the Levi-Civita connection of a Riemannian metric. From the generalized Friedmann equations of the Barthel-Kropina model, obtained by assuming that the background Riemannian metric is of the Friedmann-Lemaitre-Robertson-Walker type, an effective geometric dark energy component can be generated, with the effective, geometric type pressure, satisfying a linear barotropic type equation of state. The cosmological tests, and comparisons with observational data of this dark energy model are considered in detail. To constrain the Barthel-Kropina model parameters, and the parameter of the equation of state, we use 57 Hubble data points, and the Pantheon Supernovae Type Ia data sample. The st statistical analysis is performed by using Markov Chain Monte Carlo (MCMC) simulations. A detailed comparison with the standard $\Lambda$CDM model is also performed, with the Akaike information criterion (AIC), and the Bayesian information criterion (BIC) used as the two model selection tools. The statefinder diagnostics consisting of jerk and snap parameters, and the $Om(z)$ diagnostics are also considered for the comparative study of the Barthel-Kropina and $\Lambda$CDM cosmologies. Our results indicate that the Barthel-Kropina dark energy model gives a good description of the observational data, and thus it can be considered a viable alternative of the $\Lambda$CDM model.

This investigation is directed to understand the asymmetry in $\Delta$X variations caused due to the relative roles played by IMF Bz and IMF By in a particular interval (22:22 - 22:55 UT), during the main phase of a strong geomagnetic storm event of April 06, 2000 (Ap = 236). Two pairs of antipodal stations, being part of the SuperMAG network, are considered here. Ionospheric convection maps from SuperDARN network are used to understand spatio-temporal evolution of the DP2 ionospheric convection patterns over high-latitudes. The two-dimensional maps of equivalent currents are used to show signatures of global DP2 currents associated with the interplay effect between the two IMF components. Observations show increases in the difference in $\Delta$X variations between nearly antipodal stations from the Japanese-European/African sector with respect to the same between the nearly antipodal stations from the Pacific/American-Indian sector. This asymmetry is observed during the period when the absolute magnitude of IMF By is larger than that of IMF Bz resulting in a significant and conspicuous enhancement in IMF |By/Bz|. It is suggested that the distortions in DP2 cells and associated rotation of electrodynamic day-night divider, bring one pair of stations under the same DP2 cell and one station of the other pair under a different DP2 cell and throat flow region leading to the asymmetry in $\Delta$X variations between the antipodal stations. Therefore, the work highlights the importance of the interplay between IMF Bz and IMF By in determining the ionospheric impact over low latitudes during strong geomagnetic conditions.

We discuss a model of the universe where dark energy is replaced by electrically-charged extremely-massive dark matter. The cosmological constant has a value of the same order as the mean matter density, consistent with observations, and is obtained classically without fine-tuning.

We propose a new kind of axion model from the Grand Unified Theory (GUT) based on $SU(5)\times U(1)_{\rm PQ}$. We show that for a certain charge assignment and possible flavor models the axion is naturally hadrophobic, and provide a novel explanation for the required condition using the isospin symmetry. If this axion is the QCD axion that solves the strong CP problem, its photon coupling is larger than the conventional GUT QCD axion by a factor of $\sim 3.6$. Furthermore, in order to satisfy the limit on the axion-electron coupling from the tip of red giant branch, we impose the condition of electrophobia to determine a possible PQ charge assignment consistent with GUT. Then we discuss the possibility that the hadrophobic and electrophobic axion is an inflaton and dark matter as in the ALP miracle scenario. Interestingly, in the viable parameter region the strong CP phase must be suppressed, providing another solution to the strong CP problem. This scenario is intimately linked to flavor physics, dark matter searches, and stellar cooling. Detecting such an axion with peculiar couplings together in various experiments would be a probe for GUT as well as the origin of flavor.

We study the properties of hybrid stars containing a color superconducting quark matter phase in their cores, which is described by the chirally symmetric formulation of the confining relativistic density functional approach. It is shown that depending on the dimensionless vector and diquark couplings of quark matter, the characteristics of the deconfinement phase transition are varied, allowing us to study the relation between those characteristics and mass-radius relations of hybrid stars. Moreover, we show that the quark matter equation of state (EoS) can be nicely fitted by the Alford-Braby-Paris-Reddy model that gives a simple functional dependence between the most important parameters of the EoS and microscopic parameters of the initial Lagrangian. Based on it, we analyze the special points in which several mass-radius curves intersect. To find a distinguishable observational characteristic of the stars with the same mass and radius in the special points and probe their interior composition we calculate the frequencies of the fundamental mode of radial oscillations.