Papers for Monday, Jun 16 2025

This paper presents an overview of the U.S. federal civil space budget between FY23 and proposed spending in FY25, providing a foundational reference dataset for civil space budget analyses. Projects that support, enable, or leverage space activities for civil purposes are found in more than 100 individual line items spread across 17 federal departments and agencies and are funded by 4 different appropriations bills. Across all these elements, civil space-related appropriations total roughly 44 billion dollars in FY25, of which NASA constitutes about 58 percent (Figure 1). To better view the cross-cutting nature of space missions and the support that enables them, the second half of this report introduces a novel representation of the civil space budget by organizing the data into six national priority areas: American Leadership and Manufacturing; Workforce Development; Fundamental Science; Efficiency, Improvements, and Growth; Homeland Security; Infrastructure, Energy, and Resiliency; and Remote Sensing Applications (Figure 2). This organization of the data highlights the ubiquity of space-related activity throughout diverse sectors to reach the same common goal.

Higher order finite volume schemes for magnetohydrodynamics (MHD) and relativistic magnetohydrodynamics (RMHD) are very valuable because they allow us to carry out astrophysical simulations with very high accuracy. However, astrophysical problems sometimes have unusually large Mach numbers, exceptionally high Lorentz factors and very strong magnetic fields. All these effects cause higher order codes to become brittle and prone to code crashes. In this paper we document physical constraint preserving (PCP) methods for treating numerical MHD and RMHD. While unnecessary for standard problems, for stringent astrophysical problems these methods show their value. We describe higher order methods that allow divergence-free evolution of the magnetic field. We present a novel two-dimensional Riemann solver. This two-dimensional Riemann solver plays a key role in the design of PCP schemes for MHD and RMHD. We present a very simple PCP formulation and show how it is amalgamated with the evolution of face-centered magnetic fields. The methods presented here are time-explicit and do not add much to the computational cost. We show that the methods meet their design accuracies and work well on problems that would otherwise be considered too extreme for typical higher order Godunov methods of the type used in computational astrophysics.

Upcoming cosmic microwave background (CMB) experiments will measure temperature fluctuations on small angular scales with unprecedented precision, enabling improved measurements of the kinetic Sunyaev-Zel'dovich (kSZ) effect. This secondary anisotropy has emerged as a valuable probe of the distribution of ionized electrons in the post-recombination Universe. Although the sensitivity of the kSZ effect has recently been utilized to study the high-redshift epoch of hydrogen (H) reionization, its redshift-integrated nature -- combined with anticipated improvements in measurement precision -- suggests that accounting for the later epoch of helium (He) reionization will become increasingly important in the near future. Joint characterization of the epochs will allow for a more coherent understanding of early-star and -quasar formation, as these sources drive the ionization of H and He in the intergalactic medium. In this paper, we extend the kSZ higher-order statistic introduced by Smith \& Ferraro (2017) to forecast the ability of upcoming CMB surveys to probe the morphology of both H and He reionization. Moreover, given that upcoming large-scale structure surveys will trace density fluctuations at redshifts overlapping with the epoch of He reionization, we propose a novel cross-correlation between the kSZ higher-order statistic and galaxy survey measurements. Using a joint information-matrix analysis of H and He reionization, we show that next-generation CMB and galaxy surveys will have sufficient statistical power to characterize the patchy morphology of H reionization and set constraints on the redshift evolution of its He counterpart.

A commonly employed method to detect protoclusters in the young universe is the search for overdensities of massive star forming galaxies, such as submillimeter galaxies (SMGs), around high-mass halos, including those hosting quasars. In this work, we study the Megaparsec environment surrounding nine physically associated quasar pairs between $z=2.45$ and $z=3.82$ with JCMT/SCUBA-2 observations at 450 $\mu$m and 850 $\mu$m covering a field of view of roughly 13.7 arcmin in diameter (or 32 Mpc$^2$ at the median redshift) for each system. We identify a total of 170 SMG candidates and 26 non-SMG and interloper candidates. A comparison of the underlying 850 $\mu$m source models recovered with Monte Carlo simulations to the blank field model reveals galaxy overdensities in all fields, with a weighted average overdensity factor of $\delta_{\rm cumul} = 3.4 \pm 0.3$. From this excess emission at 850 $\mu$m, we calculate a star formation rate density of $1700 \pm 100$ M$_{\odot}$ yr$^{-1}$ Mpc$^{-3}$, consistent with predictions from protocluster simulations and observations. Compared to fields around single quasars, those surrounding quasar pairs have higher excess counts and more centrally peaked star formation, further highlighting the co-evolution of SMGs and quasars. We do not find preferential alignment of the SMGs with the quasar pair direction or their associated Ly$\alpha$ nebulae, indicating that cosmic web filaments on different scales might be traced by the different directions. Overall, this work substantiates the reliability of quasar pairs to detect overdensities of massive galaxies and likely sites of protocluster formation. Future spectroscopic follow-up observations are needed to confirm membership of the SMG candidates with the physically associated quasar pairs and definitively identify the targeted fields as protoclusters.

Ray tracing algorithms that compute pulse profiles from rotating neutron stars are essential tools for constraining neutron-star properties with data from missions such as NICER. However, the high computational cost of these simulations presents a significant bottleneck for inference algorithms that require millions of evaluations, such as Markov Chain Monte Carlo methods. In this work, we develop a residual neural network model that accelerates this calculation by predicting the observed flux from the surface of a spinning neutron star as a function of its physical parameters and rotational phase. Leveraging GPU-parallelized evaluation, we demonstrate that our model achieves many orders-of-magnitude speedup compared to traditional ray tracing while maintaining high accuracy. We also show that the trained network can efficiently accommodate complex emission geometries, including non-circular and multiple hot spots, by integrating over localized flux predictions.

Dust substructures in protoplanetary discs can be signatures of embedded young planets whose detection and characterisation would provide a better understanding of planet formation. Traditional techniques used to link substructures' morphology to the properties of putative embedded planets present several limitations that the use of deep learning methods has partly overcome. In our previous work, we developed DBNets, a tool exploiting an ensemble of Convolutional Neural Networks (CNNs) to estimate the mass of putative planets in disc dust substructures. This inference problem, however, is degenerate as planets of different masses could produce the same rings and gaps if other physical disc properties were different. In this paper, we address this issue improving our simulation-based inference pipeline to estimate the full posterior distribution for the planet mass and three additional disc properties: the disc $\alpha$-viscosity, the scale height and the dust Stokes number. We also address some minor issues of our previous tool. The new pipeline involves a CNN that summarises the input images in a set of summary statistics, followed by an ensemble of normalising flows that model the inferred posterior for the target properties. We tested our pipeline on a dedicated set of synthetic observations using the TARP test and standard metrics, demonstrating its accuracy and precision. Additionally, we use the results obtained on the test set to study the degeneracies between pairs of parameters. Finally, we apply the developed pipeline to a set of 49 gaps in 34 protoplanetary discs' continuum observations. The results show typically low values of $\alpha$-viscosity, disc scale heights, and planet masses, with 83% of them being lower than 1M$_J$. These low masses are consistent with the non-detections of these putative planets in direct imaging surveys. Our tool is publicly available.

We present a framework for relating gravitational wave (GW) sources to the astrophysical properties of spectroscopic galaxy samples. We show how this can enable using clustering measurements of gravitational wave (GW) sources to infer the relationship between the GW sources and the astrophysical properties of their host galaxies. We accomplish this by creating mock GW catalogs from the spectroscopic Sloan Digital Sky Survey (SDSS) DR7 galaxy survey. We populate the GWs using a joint host-galaxy probability function defined over stellar mass, star formation rate (SFR), and metallicity. This probability is modeled as the product of three broken power-law distributions, each with a turnover point motivated by astrophysical processes governing the relation between current-day galaxy properties and BBH mergers, such as galaxy quenching and BBH delay time. Our results show that GW bias is most sensitive to host-galaxy probability dependence on stellar mass, with increases of up to $\sim O (10)\%$ relative to galaxy bias as the stellar mass pivot scale rises. We also find a notable relationship between GW bias and SFR: when the host-galaxy probability favors low-SFR galaxies, the GW bias significantly increases. In contrast, we observe no strong correlation between GW bias and metallicity. These findings suggest that the spatial clustering of GW sources is primarily driven by the stellar mass and SFR of their host galaxies and shows how GW bias measurements can inform models of the host-galaxy probability function.

We present a new lens model for the $z=0.375$ galaxy cluster Abell 370 based on previously spectroscopically confirmed lensed galaxies and new lensed systems identified in JWST data, including recent data from the MAGNIF program. Based on the best models able to reproduce two radial arcs near the BCGs, we compare the stellar mass to the total mass from the lens model and find that the fraction of dark matter in the south BCG is consistent with $\Lambda$CDM while in the north BCG we find a very small amount of dark matter, more consistent with alternative models to $\Lambda$CDM. We discuss possible causes for this and conclude that additional data is needed to clarify the situation. We study the lensing properties, magnification, time delay and strength of the critical curve, along the Dragon arc, where previous studies have reported tens of alleged microlensing events from supergiant stars at $z=0.7251$. The new lens model is able to reproduce the distribution of microlensing events with great accuracy. Some of the microlensing events may be reinterpreted as long-period Cepheid in future observations. We consider this possibility and study in more detail the challenges for such detection from intervening microlenses.

Numerous studies have established that the environment influences the physical properties of a galaxy. While gas inflows supply the fuel for SF, high density and temperature conditions suppress SF activity through various quenching processes. Investigations into large scale structures, such as filaments and overdense regions in the cluster outskirts, have focused on the low z. To move to intermediate z and explore galaxy pathways combined with environmental effects, it is crucial to join wide field spectroscopy and deep photometry. Our primary objective is to spectroscopically analyze the photometric overdensities observed by Estrada et al.(2023) in the outskirts of massive cluster MACS J0416.1-2403 (z=0.397), interpreted as evidence of ongoing group infall, i.e. the pre processing scenario, and to investigate the behavior of galaxies in the outskirts about their g-r color, Mstar, and local density, emphasizing the influence of the environment on galaxy evolution. We conducted a spectroscopic analysis out to 5.5R200, using the AAOmega spectrograph. The large FoV and depth allowed us to explore galaxies up to the cluster periphery and across a wide Mstar range, reaching down to the limit of dwarf galaxies. Redshifts were obtained through independent but comparable methods: Redrock, EZ, and Redmost. We identified 148 new spectroscopic cluster members from a sample of 1236 objects. We found 81 galaxies located in filamentary and overdense regions, supporting the role of filamentary infall in the cluster mass assembly history. Our analysis revealed that galaxies in high density regions are more massive, redder, and more passive, compared to galaxies in low density regions that appear to be bluer, less massive, and more SF. These findings underscore the significance of environmental effects and the role of pre processing in shaping galaxy properties before cluster infall.

On 2032 December 22 the 60 m diameter asteroid 2024 YR4 has a 4% chance of impacting the Moon. Such an impact would release 6.5 MT TNT equivalent energy and produce a ~1 km diameter crater. We estimate that up to 10^8 kg of lunar material could be liberated in such an impact by exceeding lunar escape speed. Depending on the actual impact location on the Moon as much as 10% of this material may accrete to the Earth on timescales of a few days. The lunar ejecta-associated particle fluence at 0.1 - 10 mm sizes could produce upwards of years to of order a decade of equivalent background meteoroid impact exposure to satellites in near-Earth space late in 2032. Our results demonstrate that planetary defense considerations should be more broadly extended to cis-lunar space and not confined solely to near-Earth space.

It has long been suggested that a fraction of the dark matter in the Universe could exist in the form of primordial black holes (PBHs) that have existed since the radiation dominated era. Recent studies have suggested that these PBHs may be the progenitors to the population of high-redshift, supermassive black holes (SMBHs) observed since the launch of JWST. For the first time, we have included PBHs in cosmological simulations, to test whether PBHs can sink to the center of collapsing halos, locate dense gaseous regions experience significant growth. We tested PBH-to-DM mass ratios of $f_{\rm PBH}$ = $10^{-4}$ and $10^{-3}$, with an initial PBH mass of 1000 M$_\odot$, as inspired by recent observational constraints. We find that at $f_{\rm PBH} = 10^{-3}$, a number of PBHs were able to embed themselves in dense gas and grow to $10^{4}$-$10^{5}$ M$_\odot$ by $z=20$. These intermediate black holes (IMBHs) are possible progenitors to the highest redshift SMBH observations such as GNZ-11 ($10^{6}$ M$_\odot$ by $z=10$), outperforming light seed black hole (BH) growth seen in recent simulations without the need to invoke heavy seeding prescriptions. On the other hand, $f_{\rm PBH} = 10^{-4}$ resulted in no significant BH growth, emphasizing that the ability of PBHs to act as SMBH seeds is sensitive to the true value of $f_{\rm PBH}$ in the Universe, and showing that the $f_{\rm PBH} =10^{-4}-10^{-3}$ boundary marks the threshold above which SMBH seeding via 1000 M$_\odot$ PBHs becomes effective. This is the first step towards building a realistic PBH framework in cosmological simulations.

We present a second-order calculation of relativistic large-scale-structure observables in cosmological perturbation theory, specifically the "cosmic rulers and clock", which are the building-blocks of any other large-scale-structure observable, including galaxy number counts, on large scales. We calculate the scalar rulers (longitudinal perturbation and magnification) and the cosmic clock to second order, using a fully non-linear covariant definition of the observables. We validate our formulae on three non-trivial space-time metrics: two of them are null tests on metrics which are obtained by applying a gauge transformation to the background space-time, while the third is the "separate universe" curved background, for which we can also compute the observables exactly. We then illustrate the results by evaluating the second-order observables in a simplified symmetric setup. On large scales, they are suppressed over the linear contributions by $\sim 10^{-4}$, while they become comparable to the linear contributions on mildly non-linear scales. The results of this paper form a significant (and the most complicated) part of the relativistic galaxy number density at second order.

We report the detection of a new HI absorption system associated with the radio source NVSS J164725+375218 at a redshift of z=2.327, identified through a blind survey conducted by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). This marks the fifth detection of an associated system at z > 2. By analyzing a subset of available data, we conducted a blind survey for HI absorption systems within the redshift range of 0.78 to 2.55 along 202 lines of sight in the declination range of 35 to 60 degrees. We detected three HI absorbers, including two previously known intervening systems and one newly discovered associated system. By fitting the absorption profile with a number of Gaussian functions, we put lower limits on the optical depth, velocity integrated optical depth and the ratio between the HI column density and the spin temperature of the absorption systems. These results represent a validation of CHIME's absorber search strategy, and demonstrate CHIME's ability to discover new absorbers even in small subsets of its full dataset.

Globular clusters exhibit star-to-star chemical variations, traceable through both photometric and spectroscopic data. In this study, we investigate chemical variations in the globular cluster NGC104 (47Tucanae), aiming to trace multiple stellar populations across evolutionary phases and examine how the C/N anti-correlation evolves from the main sequence (MS) to the asymptotic giant branch (AGB). We also assess the impact of these populations on the interpretation of the V vs. V-I diagram. [C/Fe] and [N/Fe] abundances are obtained from CN and the CH features, while atmospheric parameters are homogeneously derived from photometry. The inferred abundances allow us to disentangle multiple populations along the CMD and refine cluster parameters. We find that MS stars are more C- and N-rich than their red giant branch, horizontal branch, and AGB counterparts. The C/N anti-correlation shifts during the sub-giant branch phase, coinciding with the first dredge-up. Interestingly, stars with different C and N abundances occupy distinct regions of the V vs V-I diagram, a pattern not attributable to differential reddening. Proper CMD fitting requires two isochrones with differing helium content, metallicity, and possibly age.

The HI mass function is a crucial tool to understand the evolution of the HI content in galaxies over cosmic times and to constrain both the baryon cycle in galaxy evolution and the reionization history of the Universe. We aim to derive semi-empirical constraints at $z\sim 0.37$ by combining literature results on the stellar mass function from optical surveys with recent findings on the $M_{\rm HI}-M_\star$ scaling relation derived via spectral stacking analysis applied to 21-cm line interferometric data from the MIGHTEE and CHILES surveys, conducted with MeerKAT and the VLA, respectively. We draw synthetic stellar mass samples directly from the publicly-available results underlying the analysis of the COSMOS2020 galaxy photometric sample. Afterwards, we convert $M_\star$ into $M_{\rm HI}$ using analytical fitting functions to the data points from HI stacking. We then fit a Schechter function to the median HIMF from all the samples via MCMC. We finally derive the posterior distribution for $\Omega_{\rm HI}$ by integrating the models for the HIMF built from the posteriors samples of the Schechter parameters. We find evolution of the HIMF at $z\sim 0.37$ with respect to results at $z\sim 0$ from the ALFALFA survey and at $z\sim 1$ from uGMRT data. Our results for $\Omega_{\rm HI}$ are in broad agreement with other literature results, and follow the trend on $\Omega_{\rm HI}$ as a function of redshift. The derived value $\Omega_{\rm HI}=\left(7.02^{+0.59}_{-0.52}\right)\times10^{-4}$ at $z\sim 0.37$ from the combined analysis deviates at $ \sim 2.9\sigma$ from the ALFALFA result at $z\sim 0$. We conclude that the HIMF and $\Omega_{\rm HI}$ constraints that we derive from state-of-the-art deep interferometric surveys suggest an evolution of the HIMF and of the cosmic HI density, supporting a picture of smooth transition of the HI content of galaxies from $z\sim 0$ to $z\sim 1$.

Primordial black hole (PBH) binaries experience strong gravitational perturbations in the case of their initial clustering, which significantly affects the dynamics of their mergers. In this work, we develop a new formalism to account for these perturbations and track the evolution of the binary orbital parameters distribution. Based on this approach, we calculate the merger rate of PBH binaries and demonstrate that its temporal evolution differs greatly from that of isolated binary systems. Moreover, PBH clustering produces distinctive features in the stochastic gravitational-wave background: the canonical $2/3$ spectral slope transforms to $\Omega_{\rm gw} \propto \nu^{-65/28}$ in a certain frequency band. These predictions can be probed in future gravitational wave observations, opening up new opportunities to test the clustering of PBHs and their contribution to dark matter.

Although the standard cosmological model is capable of explaining most current observational data, it faces some theoretical and observational issues. This is the main motivation for exploring alternative cosmological models. In this paper, we focus on a novel proposal that consists in adding an infinite tower of higher-order curvature invariants to the usual Einstein-Hilbert action. We obtain the late-time background evolution for three families of models that can be obtained from this proposal. We use recent data from Cosmic Chronometers and type Ia supernovae to test the late-time predictions of our models. In addition, we consider estimations from the Age of the Older Globular Clusters to constrain our models. While some of the studied cases are ruled out by the data, we show that there are particular cases of the GILA model that can explain current data.

We report our discovery of a faint nebula surrounding a previously little-studied 15th-mag variable star, ASASSN-19ds, in the southern-hemisphere constellation Antlia. Spectra verify that the star is a cataclysmic variable (CV). Using new and archival photometry, we confirm that ASASSN-19ds is an eclipsing binary with an orbital period of 0.139 days (3.34 hr). Moreover, its out-of-eclipse brightness shows a "sawtooth" light curve with an amplitude of $\sim$1~mag and an interval between peaks that varies between about three to nearly five weeks. Its mean absolute magnitude in the Gaia system is $M_G=+6.5$. These combined properties lead to a classification of ASASSN-19ds as a Z Camelopardalis-type CV. We obtained deep narrow-band images of the nebulosity, using modest-sized telescopes and extremely long exposure times. Our imagery reveals a bipolar morphology, with thin arcs at the ends of the major axis, likely indicating an interaction with the interstellar medium. We consider several scenarios for the origin of the nebula, but from the existing information we are unable to distinguish between it being ejecta from an unobserved classical-nova outburst several centuries ago, or an ancient planetary nebula. Future observations should be able to decide between these possibilities. At the star's distance of only $\sim$557 pc, a nova eruption would have been a spectacular naked-eye event.

Galaxy groups are more susceptible to feedback from the central active galactic nuclei (AGN) due to their lower gravitational binding energy compared to clusters. This makes them ideal laboratories to study feedback effects on the overall energy and baryonic mass budget. We study the LOFAR-detected galaxy group Nest200047, where there is clear evidence of multiple generations of radio lobes from the AGN. Using 140 ks Chandra and 25 ks XMM-Newton data, we investigate thermodynamic properties of the the intragroup medium including any excess energy due to the central AGN. We also investigate X-ray properties of the central black hole and constrain the $2-10$ keV X-ray flux. We used spectral analysis techniques to measure various thermodynamic profiles across the whole field of view. We also used both imaging and spectral analysis to detect and estimate the energy deposited by potential shocks and cavities. Due to the faint emission from the object beyond the core, various background effects were considered. Nest200047 has significant excess entropy, and the AGN likely contributes to a part of it. There is an excess energy of $(5-6.5) \times 10^{60}$ erg within 400 kpc, exceeding the binding energy. The pressure profile indicates that gas is likely being ejected from the system, resulting in a baryon fraction of $\sim4\%$ inside $r_{500}$. From scaling relations, we estimate a black hole mass of $(1-4)\times 10^9 M_{\odot}$. An upper limit of $2.1 \times 10^{40}$ erg s$^{-1}$ was derived on the black hole bolometric luminosity, which is $\sim$2.5% of the Bondi accretion power. Nest200047 is likely part of a class of over-heated galaxy groups like ESO 3060170, AWM 4 and AWM 5. Such excessive heating may lead to high quenching of star formation. Moreover, the faint X-ray nuclear emission in Nest is likely due to the accretion energy being converted into jets rather than radiation.

The origin of jets in young stellar objects (YSOs) remains a subject of active investigation. We present a 3D non-ideal magnetohydrodynamic simulation of jet launching in YSOs, focusing on the interaction between the stellar magnetosphere and the circumstellar disk. At the beginning of the simulation, the magnetosphere partially opens, forming two oppositely directed magnetic field regions: one threading the star and the other threading the inner disk. The latter dominates over the original disk field at small radii and contributes to launching a disk wind. In our model, the jet is launched from the interface between these regions by toroidal magnetic pressure generated along ``two-legged'' field lines, anchored at a magnetically dominated stellar footpoint and a mass-dominated point on the disk surface. Outflows are driven along these lines via a ``load-fire-reload'' cycle: in the ``load'' stage, differential rotation between the stellar and disk footpoints generates a toroidal magnetic field; in the ``fire'' stage, vertical gradients in toroidal field strength drive the outflow and release magnetic energy; and in the ``reload'' stage, magnetic reconnection between oppositely directed field lines resets the configuration, enabling the cycle to repeat. This process occurs rapidly and asynchronously across azimuthal angles, producing a continuous, large-scale outflow. From an energetic perspective, Poynting flux transports the toroidal field from the vicinity of the star into the polar cavity, powering the jet. Comparison with a disk-only model shows that the rotating stellar magnetosphere promotes bipolar jet launching by shaping a magnetic field geometry favorable to symmetric outflows.

We present a new program aimed at developing a new generation of micromirror devices specifically tailored for astronomical applications, multi-slit spectroscopy in particular. We first overview the general characteristics of Multi-Object-Spectrographs based on the current Digital Micromirror Devices (DMDs), with particular focus on the newly deployed SAMOS instrument at the 4.1 m SOAR telescope on Cerro Pachon. We illustrate the operational advantages of DMD-based instruments and the technical limitations of the currently available devices, the DMDs produced by Texas Instruments (TI). We then introduce the baseline and target parameters of the new Micro-Mirror-Devices (MMDs) that we plan to develop with the goal of reaching TRL-5 by mid-2029 as required by the Habitable Worlds Observatory (HWO) timeline. We conclude with a brief illustration of the exciting potential of MMD-based spectrographs for an 8 m class space telescope like HWO.

Using continuum and $\text{C}^{18}\text{O}\:(2-1)$ line data obtained from the large ALMA program FAUST, we studied the structure of the protostellar binary system L1551 IRS5 at scales between 30 and 3,000 au to constrain its properties, from the circumstellar and circumbinary disks up to the envelope and outflow scales, which exhibits complex and entangled structures at the scales of its inner and outer envelopes, presumably caused by the influence of the central binary. Assuming a dust-to-gas ratio of 100, we calculated the dust+gas mass for the circumbinary disk and each circumstellar disk of the binary, obtaining 0.018 M$_{\odot}$, for the circumbinary disk, 0.004 M$_{\odot}$, and 0.002 M$_{\odot}$, for the northern and southern circumstellar disk respectively. From the line emission, we retrieved the gas masses for each structure component. With the $\text{C}^{18}\text{O}\:(2-1)$ PV diagram along the circumbinary disk, we were able to constrain the centrifugal barrier, $r_{CB}=55$ au, update the specific angular momentum, $j\sim270$~au~km~s$^{-1}$. We built an analytical model that can be used to predict the influence of the morphology of the outflow and a few dynamic features that can reproduce the system emission, allowing us to explain and discern the outflow contribution from the complex emission due to the binary. Additionally, we inferred the density power law index, $\alpha=1.7$, and the envelope rotation velocity, $v_{c}=2$~km~s$^{-1}$. Finally, the observations gave us the physical constraints to obtain a coherent outflow model for L1551 IRS5.

The rapid increase in satellite launches in recent years, and the pressure of launches planned into the next decade, demands an improvement in the efficiency of space domain awareness facilities. Optical facilities form an important component of global space domain awareness capabilities, however traditional optical telescopes are restricted to observing satellites during a small twilight window. In this work we explore expanding this operational period to encompass the entire day to dramatically improve the observing opportunities at a single site. We explore daytime space domain awareness observations with the Huntsman Telescope Pathfinder, an instrument built using predominantly off the self components, and Canon telephoto lenses. We report successful detections and photometric light curves of 81 Starlink satellites from Sun altitudes ranging 20 degrees to midday. Starlink satellites are found to be particularly bright at $3.6 \pm 0.05$ mag, $\sigma = 0.6 \pm 0.05$ mag in Sloan r', or $\sim 11\times$ brighter than twilight conditions. We conclude this surprising observed brightness is due to the contribution of Earthshine beneath the orbiting satellites. We also compare our observations to existing satellite optical brightness models and find that satellite optical brightness during the day can only be well described by a model including an Earthshine component. We find that observed light curves are more complex than simple geometric models predict, but generally agree within an order of magnitude. Finally we suggest improvements to satellite optical brightness models by incorporating weather data to measure the actual Earthshine under a satellite.

We present a library of the major spiral arm models (and maps) of the Galaxy. The package is written in Python, and allows the user to both extract the 2D trace and overplot the spiral arms in Cartesian/Polar coordinates in both Heliocentric (HC) and Galactocentric (GC) frames. The current version is a compilation of 8 models (and maps) covering a range of tracers (stars, gas). Other models can also be added upon request.

We report the detection of a burst of emission over a 695.5 MHz-1031.5 MHz bandwidth by the Australian Square Kilometre Array Pathfinder, ASKAP. The burst was localised through analysis of near-field time delays to the long-decommissioned Relay 2 satellite, and exhibited a dispersion measure of $2.26 \cdot 10^{-5}$ pc cm$^{-3}$ -- 69.7 TECU, consistent with expectations for a single pass through the ionosphere. After coherent dedispersion, the burst was determined to be less than 30 ns in width, with an average flux density of at least 300 kJy. We consider an electrostatic discharge (ESD) or plasma discharge following a micrometeoroid impact to be plausible explanations for the burst. ESDs have previously been observed with the Arecibo radio telescope, but on 1000 times longer timescales. Our observation opens new possibilities for the remote sensing of ESD, which poses a serious threat to spacecraft, and reveals a new source of false events for observations of astrophysical transients.

The Large Millimeter Telescope Alfonso Serrano (LMT), is the largest millimeter radio telescope in the world, and was founded in 2006. This radio telescope is the final product of a collaboration agreement between Mexico and the United States in the 1990s. It is located on top of an extinct volcano in Mexico at an altitude of 4600 meters above sea level. In 2018, the University of Manchester and the Rutherford Appleton Laboratory signed an agreement with the Instituto Nacional de Astrofisica Optica y Electronica (INAOE) to train Mexican astronomers in high-frequency radio receiver construction techniques by designing an innovative device called Collaborative Heterodyne Amplifier Receiver for Mexico (CHARM) designed to work at a frequency of 345 GHz. The research team, composed of British and Mexican technicians and scientists, installed CHARM at the LMT in 2019 and began testing the equipment until the COVID-19 pandemic shut it down in March 2020. This paper describes the collaboration process between Mexico and the United Kingdom, facilitated by a British institution dedicated to supporting scientific projects in developing countries, the Global Challenges Research Fund (GCRF).

Data tables on the equation of state (EOS) and microscopic structures for cold dense stellar matter with proton fractions $Y_p =0.01$-$0.65$ and baryon number densities $n_\text{b}=10^{-8}$-$2 \ \mathrm{fm}^{-3}$ are obtained adopting 13 different relativistic density functionals, i.e., NL3, PK1, PK1r, GM1, MTVTC, DD-LZ1, PKDD, DD-ME2, TW99, DD-MEX, DD-MEX1, DD-MEX2, and DD-MEY. The EOSs of dense stellar matter inside neutron stars with baryon number densities $n_\text{b}=7.6\times 10^{-11}$-$2 \ \mathrm{fm}^{-3}$ are obtained as well fulfilling $\beta$-stability condition. In general, the dense stellar matter exhibits droplet phase at $n_\mathrm{b}\lesssim 0.015\ \mathrm{fm}^{-3}$, while more exotic structures such as rods, slabs, tubes, and bubbles appear sequentially as density increases. The critical proton fractions $Y_p^\mathrm{drip}$ ($\approx 0.26$-0.31) for neutron drip are obtained, where neutron gas emerges outside of nuclei at $Y_p< Y_p^\mathrm{drip}$. For dense stellar matter at small densities ($n_\text{b}\lesssim 10^{-5} \ \mathrm{fm}^{-3}$) or large proton fractions ($n_\text{b}\lesssim0.1 \ \mathrm{fm}^{-3}$ and $Y_p\gtrsim Y_p^\mathrm{drip}$), the EOSs and microscopic structures are generally insensitive to the adopted density functionals. With the onset of neutron drip at $Y_p\lesssim Y_p^\mathrm{drip}$, the uncertainties emerge and peak at $n_\text{b} \approx 0.02 \ \mathrm{fm}^{-3}$ within the range $10^{-5} \lesssim n_\text{b}\lesssim0.1 \ \mathrm{fm}^{-3}$. At $n_\text{b}\gtrsim0.1 \ \mathrm{fm}^{-3}$, the dense stellar matter becomes uniform and muons eventually appear, where the uncertainties in the EOSs grow significantly.

The IceCube Neutrino Observatory, located at the geographic South Pole, comprises a surface component, IceTop, and an optical in-ice array. This unique com\-bi\-na\-tion allows for coincident measurements of low-energy ($\sim \rm{GeV}$) and high-energy ($\gtrsim 400\,\rm{GeV}$) muons produced in cosmic-ray air showers. The ratio of the low- and high-energy muon yields can constitute a useful tool not only for composition analyses but also for testing different hadronic interaction models. However, since IceTop does not feature dedicated muon detectors, the measurement of the low-energy muon component for individual air showers is challenging. In this work, a new approach for a single-event based estimation of the low-energy muon content using a two component lateral distribution function (LDF) is utilized. This method combines an analytic description for the electromagnetic and muon lateral distributions of the total signal, with an aim to reconstruct primary energy and low-energy muon number, respectively. The underlying principle of this method as well as the resulting reconstruction performance will be detailed in this work.

We propose that the Hubble tension arises due to an unaccounted additional component, that behaves as \emph{matter with pressure}. We demonstrate that this fluid remains subdominant compared to both dust and radiation throughout nearly the entire universe expansion history. Specifically, the additional fluid satisfies the Zel'dovic limit with a constant equation of state, $\omega_s > 0$, and a quite small normalized energy density, $\Omega_s$. Accordingly, this component modifies both the sound horizon and the background expansion rate, \emph{acting quite differently from early dark energy models}, without significantly affecting the other cosmological parameters. To show this, we perform a Monte Carlo Markov chain analysis of our model, hereafter dubbed $\Lambda_{\omega_s}$CDM paradigm, using the publicly available \texttt{CLASS} Boltzmann code. Our results confirm the presence of this fluid, with properties that closely resemble those of radiation. We find best-fit values that satisfy $\omega_s \lesssim \omega_\gamma$ and a relative energy density $\Omega_s / \Omega_\gamma = 0.45$, with $\omega_r$ and $\Omega_r$ the equation of state and density of photons, respectively. The effective fluid may be associated with generalized K-essence models or, alternatively, with Proca-type vector fields, albeit we do not exclude \emph{a priori} more exotic possibilities, i.e., dark radiation, axions, and so on. Physical implications of our results are analyzed in detail, indicating a statistical preference for the $\Lambda_{\omega_s}$CDM scenario over the conventional $\Lambda$CDM background.

We analyze the CS (J=2-1) line cube from the internal data release obtained by the large-scale program "ALMA CMZ Exploration Survey (ACES)" to investigate the kinematic structure of the innermost $\sim 10$ pc region of the Galaxy, which contains the high-velocity compact cloud (HVCC) at $(l,b,v_{\rm lsr})\sim(+0^\circ.02,-0^\circ.02, 100 {\rm km~s}^{-1})$ (hereafter G0.02). The longitude-velocity diagram (LVD) of the cloud draws an elliptical structure, which is interpreted as an orbital trajectory in the $(l,V_{\rm lsr})$ space of a noncircular (eccentric) motion of the molecular gas in the gravitational potential of an extended mass distribution in the central 10 pc of the Galaxy. We argue that G0.02 is a kinematic tracer of the inner potential, a rare case of a dense gas following an eccentric orbit in the nuclear gravitational field.

Aims : Extended-UV (XUV) galaxies are galaxies presenting an extended outer ultraviolet disks. Although some Giant Low Surface Brightness (GLSB) galaxies are also XUV, their relation has been seldom studied. This work aims to determine whether a sample of nine XUV galaxies can be classified as GLSBs, by analyzing their photometric properties in deep optical images. Method : The method presented here uses optical data from the Dark Energy Survey (DES) to construct surface brightness (SB) profiles for each galaxy. A characteristic UV radius is defined to examine the XUV disks. The surface brightness profiles are fitted using simple exponential functions, and the extracted parameters are compared with the literature to identify possible GLSB galaxies. We examined also other diagnostics, including color profiles. Results : The analysis of the optical surface brightness profiles of XUV galaxies reveal that they can be classified into three different families. One third meet the GLSB criteria in terms of diffuseness, another third are regular, and the remaining have a stronger decline in the outer disk than in the inner disk, opposite to GLSBs. The color profiles allowed us, in addition to distinguish one of the galaxy, NGC1140, likely resulting from a rare dwarf-dwarf merger.

We numerically analyze quasiperiodic oscillations (QPOs) using a well-established spacetime model with neutron star sources. Within the framework of general relativity, we present expressions for the fundamental frequencies of test particles in the gravitational field of a slowly rotating and slightly deformed compact object defined by the Hartle-Thorne (HT) metric. Using the Relativistic Precession Model (RPM) formulated by Stella and Morinsk, we examine quasiperiodic oscillation data from eight neutron stars in low-mass X-ray binary systems. Employing Markov Chain Monte Carlo analyses with the Metropolis-Hastings algorithm, we estimate 1-$\sigma$ and 2-$\sigma$ error bars. Finally, we compare our results with predictions from the Schwarzschild, Lense-Thirring, and Kerr metrics, demonstrating that three of the eight sources can be well explained within the Hartle-Thorne model.

We present results from an experimental study on the interaction of atomic deuterium with Mg-rich amorphous enstatite and forsterite type silicates. Infrared spectroscopy was used to examine the process. During D atom exposure, deuteroxyl group formation was observed. The cross section for OD group formation, estimated from the OD stretching band intensity with D atom fluence, is 4.2.10^{-18} cm^2 for both silicates. HD (D2) molecules form via D atom abstraction of chemisorbed H(D) atoms from OH (OD) groups, with a cross section of 7.0.10^{-18} cm^2. Quantum chemical calculations on enstatite and forsterite amorphous nano-clusters were used to analyze chemisorption and abstraction energies of H atoms. The formation of OH groups on forsterite is barrierless, while enstatite has a small energy barrier. H2 abstraction from hydroxyl groups is barrierless in both silicates. The results support our interpretation of IR spectral changes during D atom exposure as addition and exchange reactions, with catalytic molecular deuterium formation. These findings, obtained at 300 K, are relevant to astrophysical environments like photodissociation regions and interstellar clouds at lower temperatures. Amorphous silicates, like carbon grains, undergo hydrogenation in the diffuse interstellar medium due to interactions with atomic hydrogen and UV photons. The detection of these components on comet 67P/Churyumov-Gerasimenko connects primitive solar system objects to interstellar dust, offering new insights into their evolution.

The measurements of the number density of galaxy-galaxy strong lenses can be used to put statistical constraints on the foreground mass distributions. Dusty galaxies uncovered in submillimeter surveys are particularly useful in this regard because of the large volume probed by these surveys. Previous discoveries of strong galaxy-galaxy lensed dusty galaxies are predominantly the brightest in the sky discovered by Herschel, SPT, and Planck. However, models have also predicted a non-negligible fraction of strong galaxy-galaxy lensed faint dusty galaxies, which were difficult to confirm due to technical difficulties. Utilizing the deepest SCUBA-2 submillimeter survey, STUDIES, in both the COSMOS and the UDS fields, together with a red JWST color selection method, we discover a population of 13 strong galaxy-galaxy lensed faint dusty galaxies. The rich ancillary data allow us to confirm their strongly lensed nature via estimates of redshifts and lens modeling. Our systematic search has allowed us to construct the 450$\mu$m number counts of strongly lensed sources down to the flux levels about an order of magnitude fainter than previous measurements. The measured lensing fractions of $\sim$1% are consistent with predictions from models that also successfully produce the number density of the strong galaxy-galaxy lensed bright dusty galaxies. Future searches from Euclid and Roman are expected to discover orders of magnitude more strongly lensed faint dusty galaxies.

Astronomical surveys produce time-series data by observing stellar objects across multiple wavelength bands. Foundational transformer-based models, such as Astromer, encode each time-series as a sequence of embeddings of uniform dimensions. However, such models operate independently on each band at a single time and do not natively leverage information across telescope filters. We extend this framework by introducing a fusion mechanism that maps the collection of single-band embeddings to a unified sequence representation, enabling multiband modeling for downstream tasks. The challenge lies in devising a mechanism within the encoder to coordinate between data from different wavelengths, which are often recorded at asynchronous times. We pre-train multiband models on a subset of 600000 high signal-to-noise light curves from the MACHO survey and fine-tune them using the Alcock and ATLAS survey datasets. Experimental results show that both our proposed multiband architectures outperform the single-band models by approximately 10% in F1-score, with jointly pre-trained multiband encoders further improving performance over a collection of independently pre-trained single-band encoders. Furthermore, our experiments show that there are minimal differences in multiband performance when sampling individual band data asynchronously versus sampling all individual bands on the same set of time-steps. However, jointly pre-trained models can take more than twice the time to pre-train. These results demonstrate the trade-offs of the multiband approach where multivariate data are available.

We have developed a 1D planetary atmosphere model that solves in a self-consistent manner the evolution of temperature and disequilibrium chemistry in the vertical direction. Thermochemical kinetics is based on a reaction network built from scratch that includes 164 gaseous species composed of H, C, N, O, S, Si, P, Ti, He, and Ar, connected by 2352 forward reactions. The model is applied to the well-known gas giant exoplanets WASP-33b, HD209458b, HD189733b, GJ436b, and GJ1214b, and to secondary atmospheres that exoplanets characterized in the future may plausibly have. For irradiated gas giants with solar or supersolar metallicity, the corrections to the temperature due to disequilibrium chemistry are relatively small, on the order of 100 K at most, in agreement with previous studies. Although the atmospheric composition of some of these planets deviates significantly from chemical equilibrium, the impact on the temperature is moderate because the abundances of the main atmospheric species that provide opacity, such as H2O, CO2, CO, and/or CH4, are not seriously modified by disequilibrium chemistry. An impact on the temperature greater than 100 K appears in hot Jupiters due to TiO, which is predicted to be seriously depleted by UV photons in the upper layers. However, the extent of this depletion, and thus of its impact on the temperature, is uncertain due to the lack of knowledge about TiO photodestruction. In secondary atmospheres, the impact of disequilibrium chemistry on the temperature depends on the composition. In atmospheres dominated by H2O and/or CO2 the temperature is not affected to an important extent. However, reducing atmospheres dominated by CH4 and oxidizing atmospheres dominated by O2 see their temperature being seriously affected due to the important processing of the atmospheric composition induced by disequilibrium chemistry.

We propose a mass-dependent bimodality in the early evolution of galaxies. The massive track connects the super-bright galaxies at cosmic dawn ($z>8$) to the super-massive quiescent galaxies and black holes (BHs) at cosmic morning ($z=4-7$). The dark-matter halos $>10^{10.5}M_\odot$ at $z=10$ are expected to undergo feedback-free starbursts (FFB) with high star-formation efficiency in dense star clusters within compact galaxies. The less massive halos avoid FFB and form stars gradually under stellar feedback, leading to the peak star-forming galaxies at cosmic noon ($z=1-3$). The FFB and non-FFB halos originate from $>4\sigma$ and $2-3\sigma$ density peaks, respectively. The post-FFB galaxies quench their star formation soon after the FFB phase and remain quiescent due to (a) gas depletion by the FFB starbursts and outflows, (b) compaction events driven by angular-momentum loss in colliding streams within the high-sigma-peak FFB halos, (c) turbulent circum-galactic medium (CGM) that suppresses feeding by cold streams, and (d) BH feedback, being a key for complete quenching. BH feedback is enhanced by FFB-driven BH seeding and growth. It seems capable of disrupting the streams by generating CGM turbulence or photo-heating, but this remains an open challenge. The cosmic-morning quiescent galaxies are expected to be massive, compact, showing signatures of compaction, outflows and AGN, with a comoving number density $\sim 10^{-5} {\rm Mpc}^{-3}$, comparable to the super-bright galaxies at cosmic dawn and the AGN at cosmic morning. Their UV luminosity function should peak about $M_{\rm uv} \sim -22$ and contribute $\sim 10\%$ of the galaxies there.

Fast X-ray transients (FXTs) are bright X-ray flashes with durations of minutes to hours, peak isotropic luminosities of L_X,peak ~ 10^42-10^47 erg/s, and total isotropic energies of E ~ 10^47-10^50 erg. They have been detected in the soft X-ray band by Chandra, XMM-Newton, Swift-XRT, and, most recently, by Einstein Probe, which has reported more than 50 FXTs in its first year of operation. While several models have been proposed, the nature of many FXTs remains unknown. One model suggests FXTs are powered by the spin-down of newly formed millisecond magnetars, typically produced by binary neutron star (BNS) mergers. However, the BNS volumetric rate, ~10^2 Gpc^-3 yr^-1, barely overlaps with the estimated FXT rate of 10^3-10^4 Gpc^-3 yr^-1. Even within that overlap, BNS mergers would need to produce FXTs at nearly 100% efficiency. We explore whether other millisecond magnetar formation channels could account for this discrepancy. We compile rate densities for several proposed progenitors: accretion-induced collapse of white dwarfs, binary white dwarf mergers, neutron star-white dwarf mergers, and the collapse of massive stars, and convert Galactic event rates into volumetric rates using either the star formation rate or the stellar mass density distributions as a function of redshift. We find that the highest potential formation rates arise from binary white dwarf mergers and massive star collapses. However, both channels face theoretical and observational challenges: the spin and magnetic field properties of the resulting neutron stars are uncertain, and few are expected to satisfy both conditions required for FXT production. Across all scenarios, the fraction of suitable millisecond magnetars is low or poorly constrained. We conclude that they are unlikely to be the dominant progenitors of FXTs and can contribute to at most 10% of the observed FXT population.

The study of high-redshift galaxies provides critical insights into the early stages of cosmic evolution, particularly during the so-called 'cosmic noon', when star formation activity reached its peak. Within this context, the origin of the nebular emission remains an open question. In this work, we conduct a systematic, multi-wavelength investigation of a sample of z ~ 2-4 emitters from the MUSE Hubble Ultra Deep Field surveys, utilising both MUSE and JWST/NIRSpec data and extending the sample presented by previous studies. We derive gas-phase metallicities and key physical properties, including electron densities, temperatures and the production rates of hydrogen- and He+-ionising photons. Our results suggest that a combination of factors-such as stellar mass, initial mass function, stellar metallicity, and stellar multiplicity-likely contributes to the origin of the observed nebular emission. Specifically, for our galaxies with higher gas-phase metallicity (12 + log(O/H) > 7.55), we find that models for binary population with Salpeter IMF (Mup=100 Msol) and stellar metallicity ~ 0.001 (i.e., similar to that of the gas) can reproduce the observed ionising conditions. However at lower metallicities, models for binary population with `top-heavy' initial mass function (Mup = 300 Msol) and Zstar much lower < Zstar) than that of the gas are required to fully account for the observed ionising photon production. These results reinforce that the ionisation keeps challenging current stellar populations, and the ionisation problem persists in the very low metallicity regime.

The energy spectrum of cosmic rays above 2.5 EeV has been measured across the declination range $-90^\circ \leq\delta\leq +44.8^\circ$ using data from $\sim 310{,}000$ events accrued at the Pierre Auger Observatory from an exposure of $(104{,}900\pm 3{,}100)$ km$^2\,$sr$\,$yr. No significant variations of energy spectra with declination are observed, after allowing or not for non-uniformities across the sky arising from the well-established dipolar anisotropies in the arrival directions of ultra-high energy cosmic rays. Additionally, the instep feature in the spectrum at $\simeq$ 10 EeV reported previously is now established at a significance above $5\,\sigma$. The quasi-uniformity of the energy spectrum across declinations disfavors an origin for the instep from a few distinctive sources.

Thousands of exoplanets orbit nearby stars, showcasing a remarkable diversity in mass, size, and orbits. With the James Webb Space Telescope now operational, we are observing exoplanet atmospheres and aiming to reach down to small, habitable-zone exoplanets in search of signs of habitability and possibly even biosignature gases. Given the scarcity of targets, it is imperative to embrace the known diversity and consider the range of exoplanets that might host life. We review how Earth life interacts with various atmospheric gases, noting that bacteria can survive in high concentrations of gases such as H2, He, CO2, and CO. Additionally, we consider the potential for life in alternative solvents and in cloud biospheres where rocky surfaces are excessively hot, as well as in hypothesized planetary global oceans. We highlight that life fundamentally requires metal ions for catalytic reactions, suggesting that environments without surface contact need meteoritic delivery to provide these essential elements. Despite today's observational limits, a suite of next-generation telescopes is being designed specifically for exoplanet studies, promising to expand our capabilities and understanding in the future.

The interpretation of the thermal evolution of the transiently accreting neutron stars MXB 1659-29 and KS 1731-260 after an outburst is challenging, both within the traditional deep-crustal heating paradigm and the thermodynamically consistent approach of Gusakov and Chugunov that accounts for neutron diffusion throughout the crust. All these studies assume that the neutron superfluid in the crust is at rest. However, we have recently shown that a finite superflow could exist and could lead to a new gapless superfluid phase if quantized vortices are pinned. We have revisited the cooling of MXB 1659-29 and KS 1731-260 and we have found that gapless superfluidity could naturally explain their late time cooling. We pursue here our investigation by performing new simulations of the thermal relaxation of the crust of MXB 1659-29 and KS 1731-260 within a Markov Chain Monte Carlo method accounting for neutron diffusion and allowing for gapless superfluidity. We have varied the global structure of the neutron star, the composition of the heat-blanketing envelope, and the mass accretion rate. In all cases, observations are best fitted by models with gapless superfluidity. Finally, we make predictions that could be tested by future observations.

The two giant protoplanets directly imaged in the dust-depleted cavity of PDS 70 offer a unique opportunity to study ongoing planet formation. Both planets have been detected in infrared thermal emission and in H$\alpha$, indicating active accretion. We calibrate and analyse archival ALMA Band 6 and 7 observations of PDS 70 from 2019, 2021, and 2023 to search for circumplanetary material and assess its motion. Using 2D visibility modelling of the high-resolution (~0.11"x0.08" in Band 6; ~0.05"x0.05" in Band 7) dust continuum from the outer disc, we subtract the model and image the cavity at multiple epochs. We re-detect compact dust emission around PDS 70 c in all datasets with >$3.8\sigma$ significance, and tentatively detect emission near PDS 70 b at ~$3\sigma$ in Band 6, with peak fluxes of $59\pm17\mu$Jy/beam and $46\pm14\mu$Jy/beam. The relative astrometry of the compact emission around PDS 70 c is consistent with the expected position of the planet between 2019-2023. We find a peak flux difference up to $64\pm34\mu$Jy/beam at 1$\sigma$, but Bayesian analysis indicates no significant variability. We detect no flux variability in the inner disc. The inferred dust mass near PDS 70 c and in the inner disc ranges from $0.008$-$0.063 M_\oplus$ and $0.04$-$0.31 M_\oplus$, respectively, consistent with prior estimates. Finally, we measure Band 6-7 spectral indices of $2.5\pm1.2$ (PDS 70 c) and $3.2\pm0.5$ (inner disc), suggesting that the inner disc emission is dominated by optically thin dust.

Context: Solar active regions (ARs) are key manifestations of the Sun's magnetic activity, displaying diverse spatial and temporal characteristics. Their formation and evolution play a crucial role in understanding the solar dynamo and space weather. While individual ARs exhibit significant variability, ensemble averaging offers a method to extract their typical properties and evolution. Aims: This study aims to construct an average bipolar AR using ensemble averaging of observational data. By normalizing ARs in space and time, we seek to identify general trends in the evolution of magnetic flux, velocity fields, and atmospheric emissions, providing insights into the underlying physical mechanisms governing AR development. Methods: We analysed a sample of bipolar ARs observed by the Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory. The ARs were selected based on strict criteria, ensuring clear polarity separation and emergence within 60 degrees of the solar central meridian. Normalisation procedures were applied to align ARs spatially and temporally before computing an ensemble average of various observables, including line-of-sight magnetograms, Dopplergrams, and multi-wavelength intensity maps. Results: The average AR exhibits a well-defined evolutionary pattern, with flux emergence followed by peak activity and subsequent decay. The leading polarity retains coherence longer than the trailing one, consistent with previous studies. Surface flow maps revealed a diverging outflow near the emergence site before the emerged AR is clearly visible in magnetograms. Atmospheric emission variations indicate enhanced heating above the AR in later phases, possibly due to persistent reconnection events. The ensemble averaging approach highlights systematic features of AR evolution that are often obscured by individual-case variability.

The next generation of radio surveys is going to be transformative for cosmology and other aspects of our understanding of astrophysics. Realistic simulations of radio observations are essential for the design and planning of radio surveys. They are employed in the development of methods for tasks, such as data calibration and reduction, automated analysis and statistical studies in cosmology. We implemented a software for machine learning-assisted simulations of realistic surveys with the LOFAR telescope, resulting in a synthetic radio sky model and a corresponding artificial telescope observation. We employed a diffusion model trained on LoTSS observations to generate individual radio galaxy images with control over the angular size. Single sources are assembled into a radio sky model, using an input catalog from cosmological simulations. We then transformed this sky model into visibilities corresponding to a typical LoTSS pointing. We added realistic noise to this synthetic measurement and obtained our final simulated sky maps through deconvolution. We explored different ways to evaluate our resulting sky model. We were able to simulate realistic LOFAR observations, covering a sky patch of 5x5 degrees at an effective resolution of 8.5 arcseconds. The simulated sources have flux and size distributions that match real observations, and the resulting maps have sensitivities compatible with LoTSS observations. Our diffusion model is able to synthesize high-quality realistic radio galaxy images with precise control over the source sizes. This software can readily be applied to other instruments.

HD 138965 is a young A type star and member of the nearby young Argus association. This star is surrounded by a broad, bright debris disc with two temperature components that was spatially resolved at far-infrared wavelengths by Herschel. Here we present ALMA millimetre-wavelength imaging of the cool outer belt. These reveal its radial extent to be $150^{+10}_{-7}$ au with a width ($\sigma$) of 49$^{+7}_{-6}$ au (${\Delta}R/R$ = 0.77), at a moderate inclination of 49$\fdeg$9^{+3.3}_{-3.7}$. Due to the limited angular resolution, signal-to-noise, and inclination we have no constraint on the disc's vertical scale height. We modelled the disc emission with both gravitational and radiation forces acting on the dust grains. As the inner belt has not been spatially resolved, we fixed its radius and width prior to modelling the outer belt. We find astronomical silicate is the best fit for the dust composition. However, we could not reject possible scenarios where there are at least 10 \% water-ice inclusions. Combining the spatially resolved imaging by ALMA with non-detection at optical wavelengths by HST, we obtain a limit on the scattering albedo $\omega \leq 0.09$ for the debris dust in the outer belt. Analysis of the outer belt's architecture in conjunction with simple stirring models places a mass limit of $2.3~\pm~0.4 M_{\rm Jup}$ on a companion interior to the belt ($a \leq 78$ au), a factor of two improvement over constraints from high contrast imaging.

Recent data from multiple supernova catalogs and DESI, when combined with CMB, suggest a non-trivial evolution of dark energy (DE) at the $2.5-4\sigma$ CL. This evidence is typically quantified using the CPL parametrization of the DE equation-of-state parameter which corresponds to a first-order Taylor expansion around $a = 1$. However, this truncation is to some extent arbitrary and may bias our interpretation of the data, potentially leading us to mistake spurious features of the best-fit CPL model for genuine physical properties of DE. In this work, we apply the Weighted Function Regression (WFR) method to eliminate the subjectivity associated with the choice of truncation order. We assign Bayesian weights to the various orders and compute weighted posterior distributions of the quantities of interest. Using this model-agnostic approach, we reconstruct some of the most relevant background quantities, examining the robustness of our results against variations in the CMB and SNIa likelihoods. Furthermore, we extend our analysis by allowing for negative DE. Our results corroborate previous indications of dynamical DE, now confirmed for the first time using the WFR method. The combined analysis of CMB, BAO, and SNIa data favors a DE component that transitions from phantom to quintessence at redshift $z_{\rm cross}\sim 0.4$. The probability of phantom crossing lies between 96.21% and 99.97%, depending on the SNIa data set used, and hence a simple monotonic evolution of the DE density is excluded at the $\sim 2-4\sigma$ CL. Moreover, we find no significant evidence for a negative dark energy density below $z\sim 2.5-3$. Our reconstructions do not address the Hubble tension, yielding values of $H_0$ consistent with the Planck/$\Lambda$CDM range. If SH0ES measurements are not affected by systematic biases, the evidence for dynamical dark energy may need to be reassessed.

Building on the recent lattice simulations of ultra-slow-roll (USR) dynamics presented in arXiv:2410.23942, we investigate the role of the nonlinear relation between the inflaton field configuration and the curvature perturbation $\zeta$, the key observable after inflation. Using a nonperturbative $\delta N$ approach applied to the lattice output, we generate fully nonlinear three-dimensional maps of $\zeta$. This calculation captures both the non-Gaussianity arising from the nonlinear mapping between $\phi$ and $\zeta$, and the intrinsic non-Gaussianity generated around Hubble crossing by the nonlinear field dynamics, which is neglected in stochastic approaches. We find that the nonlinear mapping has a profound impact on the statistics, significantly enhancing the positive tail of the $\zeta$ probability distribution, with important implications for observable quantities. A central part of this work is the comparison with the standard perturbative treatment based on a gauge transformation, which allows us to quantify when and how the perturbative picture breaks down as fluctuations grow large. Together with arXiv:2410.23942, this work sets the basis for robust, nonperturbative predictions of primordial black hole production and scalar-induced gravitational wave emission from inflation using lattice simulations.

InflationEasy is the first lattice code specifically developed for cosmological inflation. It simulates the nonlinear dynamics of a scalar field on a three-dimensional lattice in an expanding FLRW universe, using finite-difference spatial derivatives and a staggered leapfrog integrator for time evolution. Based in part on the well-known LATTICEEASY, it incorporates several improvements tailored to inflationary applications. Among other features, InflationEasy implements a nonperturbative $\delta N$ method to compute the curvature perturbation at the end of inflation $\zeta$ directly from the lattice, enabling fully nonlinear studies of scenarios with large fluctuations or nonperturbative non-Gaussianities. The code supports a broad range of inflationary models, including those relevant for primordial black hole formation, gravitational wave production, and large-scale structure. This makes InflationEasy a versatile and lightweight tool for studying inflationary dynamics beyond the reach of perturbation theory.

We derive analytical expressions for the growth factor, $D(z)$, and density-weighted growth rate, $f\sigma_8(z)$, for coasting cosmologies, in which the scale factor is a linear function of time. We fit the latter to data from redshift space distortion measurements in the redshift range $z<2$ using the \texttt{dynesty} implementation of a nested sampling algorithm. In total, four models are tested: three coasting models with curvature parameters ${k=\{-1, 0, +1\}}$ in $H^2_0c^{-2}$ units, as well as a flat $\Lambda$CDM model. We evaluate each model's consistency with the data by applying an Anderson-Darling test for normality on the normalized residuals. For the coasting models, we obtained ${\Omega_\mathrm{m,0}=\{ 0.206^{+0.073}_{-0.061},\, 0.297^{+0.085}_{-0.073},\, 0.412^{+0.097}_{-0.086}}\}$ and ${\sigma_{8}(z=0)=\{1.071^{+0.213}_{-0.151},\,0.867^{+0.128}_{-0.097},\,0.725^{+0.080}_{-0.065}\}}$. Fitting the $\Lambda$CDM model yielded ${\{\Omega_\mathrm{m,0}=0.286_{-0.047}^{+0.053},\,\sigma_{8}(z=0)= 0.764_{-0.035}^{+0.039}\}}$. All four models are consistent with the data, though coasting models are weakly favored over the $\Lambda$CDM model, with $\log$-Bayes factors of ${\log_{10}{\mathcal{B}} = \{0.197,\, 0.234,\,0.272\}}$. We also examined whether the $S_8$ tension can be resolved by linear expansion restricted to $z<2$. The curve fitting yielded ${S_8=\{0.890^{+0.024}_{-0.024},\,0.865^{+0.024}_{-0.024},\,0.850^{+0.026}_{-0.026}\}}$ for the ${k=\{-1, 0, +1\}}$ coasting models, respectively, resulting in ${\Delta S^\mathrm{Coasting}_8=\{1.94\sigma,\,1.07\sigma,\,0.52\sigma\}}$ discrepancies with the standard $\textit{Planck}$ 2018 value. The tension level was the highest for the $\Lambda$CDM model, as the constraint from our fit is $S_8=0.746^{+0.041}_{-0.039}$, indicating a tension level of ${\Delta S_8^{\Lambda\mathrm{CDM}}=2.00\sigma}$.

Within disk galaxies, the velocity dispersion, $\sigma$, of stars increases with age, $\tau$, as measured in the Milky Way (MW) and nearby galaxies. This relation provides a key window into galactic formation history, tracing both the kinematics of stars at birth and the dynamical heating of stars after birth. We compile and compare observational measurements of the MW, M31, M33, and 16 galaxies from the PHANGS survey. The MW exhibits significantly colder stellar kinematics, with 2-3 times lower $\sigma(\tau)/v_{\phi,0}$ at a given age, than all but one other observed galaxy. Therefore, the MW is a kinematic outlier. To assess how measurement effects influence $\sigma(\tau)$, we analyze the FIRE-2 cosmological simulations, quantifying the impact of uncertainties in stellar age, aperture size, galactocentric radius, and galaxy inclination. Aperture size and galactocentric radius affect $\sigma(\tau)$ by up to a factor of $\approx2$ for stars younger than 100 Myr, with milder effects on older stars. Age uncertainties up to 40\% change the \textit{value} of $\sigma(\tau)$ at a given age by $\lesssim20\%$ but can reshape the relation with age and erase merger signatures. We compare $\sigma(\tau)/v_{\phi,0}$ in FIRE-2 simulations with observations. FIRE-2 agrees well with M31 and M33 at all measured ages, and with PHANGS for stars older than $\approx500$ Myr. The average $\sigma(\tau)/v_{\phi,0}$ in FIRE-2 is about two times higher than the MW at most ages, but the youngest stars show better agreement. The velocity ratios ($\sigma_{\phi}/\sigma_{R}$, $\sigma_{Z}/\sigma_{\phi}$, $\sigma_{Z}/\sigma_{R}$) in FIRE-2 broadly agree with the MW. We conclude that $\sigma(\tau)$ in FIRE-2, and most cosmological zoom-in simulations, reasonably matches observed nearby galaxies, but matching the MW is rare, because it is a kinematic outlier.

Dwarf galaxies satellite of the Milky Way are excellent laboratories for testing dark matter (DM) models and baryonic feedback implementation in simulations. The Sculptor 'classical' dwarf spheroidal galaxy, a system with two distinct stellar populations and high-quality data, offers a remarkable opportunity to study DM distributions in these galaxies. In this work, we infer the DM halo density distribution of Sculptor, applying a method based on spherically symmetric distribution functions depending on actions to fit the stellar structural and kinematic properties of Sculptor. The galaxy is represented via four components: two distinct stellar populations based on distribution functions, tracers within a fixed and dominant DM potential, plus the contribution of a third stellar component that accounts for possible sources of contamination. The model-data comparison accounts for the kinematics and metallicities of individual stars, allowing us to assign probabilities of membership to each star. The modeling is applied on the largest available set of spectroscopic data, which have not been previously analyzed with this objective. We find the DM distribution of Sculptor to have a logarithmic inner slope of 0.39+0.23-0.26 and a scale radius of 0.79+0.38-0.17 kpc at 1 sigma confidence level. Our results show that Sculptor DM density profile deviates from predictions of DM-only simulations at a 3 sigma level over a large range of radii. Our analysis suggests that the velocity distribution of Sculptor's two main stellar components is isotropic in the center and becomes radially anisotropic in the outskirts. Additionally, we provide predictions for the projected radial and tangential velocity dispersion profiles. We also present updated DM annihilation and decay J- and D-factors, finding J = 18.15+0.11-0.12 and D = 18.07+0.10-0.10 for an angular aperture of 0.5 degrees.

The formation of the first stars and galaxies marked the onset of cosmic structure and chemical enrichment, yet direct observations of such primordial systems remain elusive. Here we present James Webb Space Telescope spectroscopic observations of LAP1-B, an ultra-faint galaxy at redshift z_{spec}=6.625 +/-0.001, corresponding to a cosmic age of 800 million years after the Big Bang, strongly magnified by gravitational lensing. LAP1-B exhibits a gas-phase oxygen abundance of (4.2 +/- 1.8) x 10^{-3} times the solar value, making it the most chemically primitive galaxy ever identified at any epoch to date. The galaxy displays an exceptionally hard ionizing radiation field, which is inconsistent with chemically enriched stellar populations or accreting black holes, but consistent with theoretical predictions for zero-metallicity stars. It also shows an elevated carbon-to-oxygen abundance ratio for its metallicity in the interstellar medium, matching nucleosynthetic yields expected from stellar population formed in the absence of initial metals. The lack of detectable stellar continuum constrains the stellar mass to <2700 Msun, while the dynamical mass, derived from emission-line kinematics, exceeds the combined stellar and gas mass by more than two orders of magnitude, indicating the presence of a dominant dark matter halo. These observations establish LAP1-B as the most chemically primitive star-forming galaxy yet identified, offering a rare window into the earliest stages of galaxy formation.

Axion inflation models coupled to a gauge sector via a Chern-Simons term exhibit an array of interesting phenomenology including a chiral gravitational wave spectrum and primordial black hole production. They may also provide a useful mechanism for generating lepton asymmetry. The possibility to embed this class of models in UV-finite theories and their intriguing, testable, signatures make for a compelling candidate for early acceleration. Due to the Chern-Simons coupling, gauge modes may undergo a finite tachyonic growth during which non-linearities become important. Naturally, this raises the question of whether such (self) interactions can lead to thermalization during inflation. We provide a set of conservative criteria for sustained thermalization in an axion-$SU(2)$ model and chart the parameter space of the model accordingly. We find that the cold inflation regime constitutes a very significant fraction of the parameter space. Our analysis accounts for a initially vanishing as well as non-zero gauge field vacuum expectation value (VEV). We also consider the possibility of a dynamically generated VEV.

We present polarization images from the Karl G. Jansky Very Large Array (VLA) and the Giant {Metrewave} Radio Telescope (GMRT) at 5.5, 10 GHz and 663 MHz of the changing-look (CL) AGN, NGC3516. A transverse gradient in the rotation measure (RM) is detected in the northern and southern kpc-scale lobes. Such gradients have typically been suggested to be signatures of a helical magnetic (B-) field. We detect circular polarization in the core and inner jet-knot of this source which is known to host a precessing radio jet interacting with emission-line gas. Soft X-ray emission from the Chandra X-ray Observatory suggests the presence of a hot wind emerging from the nucleus of NGC3516. Taken together with the RM gradient, this presents a picture of jet+wind outflow in this Seyfert galaxy with the B-field confining both the jet and lobe emission. A magnetically driven outflow may in turn cause accretion disk warping and jet precession which is observed in the case of NGC3516.

In an era where astronomical data is expanding at an unprecedented rate, the importance of data sharing and accessibility among astronomy archives cannot be overstated. Since the 1990s, an international partnership between the Space Telescope Science Institute (STScI), the European Space Astronomy Centre (ESAC), and the Canadian Astronomy Data Centre (CADC) has been focused on this endeavor, facilitating the exchange of data from the Hubble and James Webb Space Telescopes. We will present how this collaboration has evolved over time, highlighting key milestones and innovations in decision-making, communication, and technology. Additionally, we will discuss some of the challenges we have encountered and the strategies we employed to overcome them, offering insights that could benefit future archive collaborations.

Precise localizations of fast radio bursts (FRBs) are essential for uncovering their host galaxies and immediate environments. We present the milliarcsecond-precision European VLBI Network (EVN) localization of FRB 20240114A, a hyper-active repeating FRB, achieving <90x30 mas (1-sigma) accuracy. This precision places the burst 0.5 kpc from the nucleus of its low-metallicity star-forming dwarf host at a spectroscopic redshift of z = 0.1300. Our Gran Telescopio CANARIAS (GTC) spectroscopic follow-up reveals that the dwarf FRB host is gravitationally bound to a more massive, star-forming spiral galaxy. This establishes the first known instance of an FRB residing in a satellite galaxy within a larger galactic system. This configuration, analogous to the Small Magellanic Cloud orbiting the Milky Way (but at a lower overall mass scale), expands the known diversity of FRB host environments and offers important insights for interpreting seemingly "hostless" or highly offset FRBs. Furthermore, our detailed dispersion measure (DM) budget analysis indicates that the dominant contribution to FRB 20240114A's DM likely originates from the foreground halo of the central galaxy. This finding addresses the anomalously high DM observed for this FRB and underscores the significant role of intervening foreground structures in shaping observed FRB DMs, which is important for accurate FRB-based cosmological measurements. Our results highlight the importance of deep, high-resolution optical/infrared observations (e.g., with Hubble or James Webb Space Telescopes) to fully leverage our precise radio localization and probe the immediate astrophysical birthplaces of FRB progenitors within these complex galactic systems.

Supernovae (SNe) are believed to be the dominant sources of dust production at high redshift. However, the reverse shock generated by the interaction of the SN forward shock and the interstellar medium (ISM) significantly reduces the mass of newly formed dust in SN ejecta. This study quantifies the mass, composition, and grain size distribution of surviving dust after the passage of the reverse shock using the GRASHrev model. Our analysis covers a grid of SN models with progenitor masses $13\,M_\odot\leq m_\star\leq120M_\odot$, metallicity $-3\leq\text{[Fe/H]}\leq0$, and rotation velocities $v = 0$ and $300\,\mathrm{km\,s^{-1}}$. The SN explosions occur in a uniform ISM with densities $n_\text{ISM} = 0.05, 0.5$, and $5\text{ cm}^{-3}$. We find that the larger grains ($\gtrsim10\text{ nm}$) are more resistant to destruction by the reverse shock, with amorphous carbon dominating the surviving dust mass in most models. The surviving dust mass decreases with increasing ISM density. For non-rotating progenitors, the maximum mass of dust surviving the passage of the reverse shock is $\simeq 0.02\,M_\odot$ released by SN explosions of a $120\,M_\odot$ progenitor with $\text{[Fe/H]}=0$ in the ISM density $0.5\,\text{cm}^{-3}$, corresponding to $\simeq4\%$ of the initial dust mass before the passage of the reverse shock. Among rotating progenitors, a maximum surviving mass fraction is $\simeq5\%$ with a final dust mass $\simeq0.03\,M_\odot$ in $\text{[Fe/H]}=-1$ models. Although the reverse shock has a strong destructive impact, our results indicate that, on very short timescales, SNe can enrich the ISM with carbonaceous grains ranging in size from approximately $1\text{ nm}$ to $100\text{ nm}$ (up to $\simeq1\,\mathrm{\mu m}$ in non-rotating models). This is notable given the detection of the 2175 Å extinction bump in galaxies at $z>6$, suggesting the early presence of such dust.

Atomic hydrogen constitutes the gas reservoir from which molecular gas and star formation in galaxies emerges. However, the weakness of the line means it has been difficult to directly detect in all but the very local Universe. Here we present results from the first search using the MeerKAT International Tiered Extragalactic Exploration (MIGHTEE) Survey for high-redshift ($z>0.25$) H{\sc i} emission from individual galaxies. By searching for 21-cm emission centered on the position and redshift of optically-selected emission-line galaxies we overcome difficulties that hinder untargeted searches. We detect 11 galaxies at $z>0.25$, forming the first sample of $z>0.25$ detections with an interferometer, with the highest redshift detection at $z = 0.3841$. We find they have much larger H{\sc i} masses than their low-redshift H{\sc i}-selected counterparts for a given stellar mass. This can be explained by the much larger cosmological volume probed at these high redshifts, and does not require any evolution of the H{\sc i} mass function. We make the first-ever measurement of the baryonic Tully-Fisher relation (bTFr) with H{\sc i} at $z>0.25$ and find consistency with the local bTFr, but with tentative evidence of a flattening in the relation at these redshifts for higher-mass objects. This may signify evolution, in line with predictions from hydrodynamic simulations, or that the molecular gas mass in these high-mass galaxies could be significant. This study paves the way for future studies of H{\sc i} beyond the local Universe, using both searches targeted at known objects and via pure H{\sc i} selection.

Cosmological constraints derived from weak lensing (WL) surveys are limited by baryonic effects, which suppress the non-linear matter power spectrum on small scales. By combining WL measurements with data from external tracers of the gas around massive structures, it is possible to calibrate baryonic effects and, therefore, obtain more precise cosmological constraints. In this study, we generate mock data for a Stage-IV weak lensing survey such as the Legacy Survey of Space and Time (LSST), X-ray gas fractions, and stacked kinetic Sunyaev-Zel'dovich (kSZ) measurements, to jointly constrain cosmological and astrophysical parameters describing baryonic effects (using the Baryon Correction Model - BCM). First, using WL data alone, we quantify the level to which the BCM parameters will need to be constrained to recover the cosmological constraints obtained under the assumption of perfect knowledge of baryonic feedback. We identify the most relevant baryonic parameters and determine that they must be calibrated to a precision of $\sim 10$-$20\%$ to avoid significant degradation of the fiducial WL constraints. We forecast that long-term X-ray data from $\sim 5000$ clusters should be able to reach this threshold for the parameters that characterise the abundance of hot virialised gas. Constraining the distribution of ejected gas presents a greater challenge, however, but we forecast that long-term kSZ data from a CMB-S4-like experiment should achieve the level of precision required for full self-calibration.

When neutron stars accrete matter from a companion star, this matter forms a disc around them and eventually falls on their surface. Here, the fuel can ignite into bright flashes called Type I bursts. Theoretical calculations based on state-of-the-art nuclear reactions are able to explain many features of the bursts. However, models predict that the bursts should cease at high accretion rates, whereas in many sources they disappear at much lower rates. Moreover, their recurrence times also show strong discrepancies with predictions. Although various solutions have been proposed, none can account for all the observational constraints. Here we describe a new model that explains all the contradictory behaviours within a single picture. We are able to reconstruct the conditions on the star surface that determine the burst properties by comparing data to new simulations. We find strong evidence that the physical mechanism driving the burst behaviour is the structure of the accretion disc in the regions closest to the star. This connection reconciles the puzzling burst phenomenology with nuclear physics and also opens a new window on the study of accretion processes around compact objects.

We present observations of two binary systems within the cold classical region of the Kuiper belt -- 2001 XR254 and 2016 BP81 -- obtained with the JWST Near-Infrared Spectrograph. The measured reflectance spectrum of 2001 XR254 is characteristic of the red cold classicals, with strong features due to carbon dioxide, carbon monoxide, and methanol ices. In contrast, 2016 BP81 is a blue binary, with a water-ice-rich surface composition. The two components of the 2016 BP81 binary display identical spectral profiles, consistent with coeval formation from gravitational collapse. Through qualitative and quantitative comparisons of water-ice-rich Kuiper belt objects observed with JWST, we identify a small subclass, including 2016 BP81, that appears to differ in systematic ways from the rest of the population. The relatively deep carbon dioxide ice absorption bands and enhanced signatures of aliphatic organics suggest that objects within this subclass may have originated in a distinct formation environment from the other water-ice-rich Kuiper belt objects. The implications of our findings are discussed within the context of recent models of Kuiper belt formation and evolution.

TOI-3884~b is an unusual 6.4~R$_\oplus$ planet orbiting an M4 host, whose transits display large and persistent spot-crossing events. We used the \textit{Tierras} Observatory to monitor both the long-term photometric variability of TOI-3884 and changes in the spot-crossing events across multiple transits of the planet. We show that the star rotates with a period of $11.021 \pm 0.014$~days. We simultaneously model the rotational modulation of the star and variations in transit shapes that arise due to rotation of the spot, allowing us to determine the true stellar obliquity, $\psi_\star$. The data are best described by a planet on a misaligned orbit around a highly inclined star ($\psi_\star = {76.1^\circ} ^{+2.2^\circ}_{-2.6^\circ}$; $i_\star = {24.4^\circ}^{+1.8^\circ}_{-1.4^\circ}$) that hosts a large polar starspot ($r_\mathrm{spot} = {33.1^\circ}^{+2.0^\circ}_{-1.9^\circ}$; $\lambda_\mathrm{spot} = {79.4^\circ}^{+1.4^\circ}_{-1.2^\circ}$). Archival photometry from the Zwicky Transient Facility suggests that this polar spot has persisted on TOI-3884 for at least seven years. The TOI-3884 system provides a benchmark for studying the evolution of a polar spot on an M dwarf.

Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI) show evidence of a deviation from a cosmological constant $\Lambda$ within a Bayesian analysis. In this work, we validate that frequentist constraints from profile likelihoods on the Chevallier-Polarski-Linder parameters $w_0$, $w_a$ are in excellent agreement with the Bayesian constraints when combining with Planck cosmic microwave background, Planck and Atacama Cosmology Telescope lensing, and either Pantheon+ or Dark Energy Survey Y5 supernova data. Further, we assess which datasets drive these constraints by considering the contributions to the $\chi^2$ from the individual datasets. For profile likelihoods of the matter fraction $\Omega_\mathrm{m}$, such an investigation shows internal inconsistencies when assuming $\Lambda$, which are resolved when assuming a $w_0w_a$ dark-energy model. We infer the equations of state $w(z)$ at the pivot redshifts, supporting previous interpretations that current data appears to be more sensitive to the derivative of $w(z)$ rather than a mean offset from $\Lambda$. Thus our frequentist analysis corroborates previous findings on dynamical DE.

We present the first numerical relativity simulations of the gravitational scattering of two neutron stars. Constraint-satisfying initial data for two equal-mass non-spinning sequences are constructed at fixed energy and various initial angular momenta (impact parameter) and evolved with Einstein equations through the scattering process. The strong-field scattering dynamics are explored up to scattering angles of $225^\circ$ and the threshold of dynamical captures. The transition to bound orbits is aided by significant mass ejecta up to baryon mass ${\sim}1M_\odot$. A quantitative comparison with predictions of the scattering angle from state-of-the-art effective-one-body and post-Minkowskian calculations indicates quantitative agreement for large initial angular momenta although significant discrepancies in the tidal contribution emerge towards the capture threshold. Gravitational waveforms and radiated energy are in qualitative agreement with the analogous black hole problem and state-of-the-art effective-one-body predictions. Towards the capture threshold waveforms from scattering dynamics carry a strong imprint of matter effects, including the stars' $f$-mode excitations during the close encounter. Overall, our simulations open a new avenue to study tidal interactions in the relativistic two-body problem.

We investigate a class of scalar field dark energy models non-minimally coupled to gravity, characterized by a double exponential potential and parameterized coupling {\xi}. First, we study the cosmological dynamics for a recently proposed Q-SC-CDM model. Initially, we choose two distinct values of {\xi}: 0.1 and 0.5. In case of {\xi}=0.1, the evolution of the universe is split up into three different phases: deceleration, acceleration and slow-contraction, and provide Big Crunch Singularity at distant future. However, in case of {\xi}=0.5, the phase of slow-contraction vanishes, correspondingly Big Crunch Singularity is redundant. Second, we perform the phase space analysis for Q-SC-CDM, bring new asymptotic regimes and find stable de-Sitter solution. Finally, fixing {\xi} to two representative values: {\xi} = 0.1 and 0.05, we perform a comprehensive Bayesian analysis using recent late-time cosmological observations, including Cosmic Chronometers (CC), Type Ia Supernovae (Pantheon+ and DES-SN5YR), and Baryon Acoustic Oscillation (DESI DR2) data. Our results demonstrate that both models yield constraints on key cosmological parameters \Omega_{0m}, H_0 and the sound horizon r_d that are consistent with {\Lambda}CDM within 68\% confidence level, yet exhibit mild tension with Pantheon+ measurements. We analyze the evolution of the effective equation of state, showing that the model transitions from a stiff matter phase at high redshift to a dark energy dominated phase with effective equation of state less than -0.5 at late times. Additionally, we employ the Om(z) diagnostic to distinguish our model from {\Lambda}CDM, finding minimal deviation up to redshift z \sim 2. Statistical model comparison using Akaike (AIC) and Bayesian (BIC) Information Criteria reveals moderate support for the model with {\xi} = 0.1, though {\Lambda}CDM remains statistically preferred.

We extend the study of the effect of density perturbations to the well known thermal dark matter freeze-out scenario. We find $\sim 10 \, \%$ enhancements in the cross section are required to match onto the observed relic abundance for primordial curvature perturbations $\sim 0.2$ at length scales $\sim 1/$Hubble at freeze-out. Such corrections may be of importance in scenarios in which such perturbations are present and observational signals, such as the indirect detection rate, depend sensitively on the DM mass and freeze-out cross section, e.g. near resonances associated with DM bound states.