Papers for Tuesday, Aug 05 2025

As humanity advances toward long-term lunar presence under NASA's Artemis program, the development of lunar-based manufacturing and construction (LBMC) capabilities has become increasingly critical. The high cost of transporting materials from Earth makes in-situ resource utilization (ISRU) essential, with lunar regolith serving as a promising local feedstock. Additive manufacturing (AM) offers a compelling platform for LBMC due to its geometric flexibility, material efficiency, and capacity for on-demand, site-specific production. This study investigates material extrusion (MEX) AM of polyether-ether-ketone (PEEK) composites containing 10 to 50 wt% lunar regolith simulant (LRS). PEEK and LMS-1D powders were melt-compounded via twin-screw extrusion, printed using a high-temperature chamber, and annealed at 300 degrees C. The samples were characterized through density measurements, thermal analysis, tensile testing, and microstructural and elemental mapping. All filaments exhibited densities above 96%, though as-printed porosity increased from less than 1% in neat PEEK to 7.5% at 50 wt% LRS due to elevated melt viscosity. Regolith incorporation enhanced crystallinity (17.4 to 20.5%) and elastic modulus (by 6-41%), while reducing delamination and warping, which improved dimensional accuracy and print success rates. Tensile strength declined gradually from 107 MPa to 90 MPa up to 40 wt% LRS, then dropped sharply to approximately 70 MPa at 50 wt%. Annealing improved density and stiffness for composites containing up to 30 wt% LRS, with marginal benefit at higher contents. Microstructural and elemental analyses confirmed a continuous PEEK matrix with uniformly dispersed regolith particles. This work establishes processing windows and trade-offs for regolith-rich PEEK composites, supporting ISRU-enabled AM of future lunar infrastructure.

Recent developments in AI techniques for space applications mirror the success achieved in terrestrial applications. Machine learning, which excels in data rich environments, is particularly well suited to space-based computer vision applications, such as space optical attitude sensing. Of these sensors, digital sun sensors (DSS) are one of the most common and important sensors for spacecraft attitude determination. The main challenge in using the DSS for attitude estimation are sensor errors, which limit the overall achievable estimation accuracy. However, the traditional sun sensor calibration process is costly, slow, labor-intensive and inefficient. These limitations motivate the use of AI techniques to enable more accurate and efficient DSS calibration. The objective of this work is to develop an end-to-end predictive calibration methodology for digital sun sensors to solve 2-axis state estimates utilizing a sparse submanifold convolutional neural network (SSCNN). We find that the proposed framework can achieve state-of-the-art performance on synthetic data with a mean accuracy of 0.005° for the two sun angle estimates. Furthermore, the model is highly capable of implicitly learning complex noise patterns and handling mixed noise types, thereby greatly improving the model robustness and accuracy to real-world applications. The main contributions of this work are: (1) the first application (to our knowledge) of a CNN regression model to the problem of DSS predictive calibration, (2) the introduction of a fused end-to-end training approach for DSS calibration, (3) the creation of a publicly available physics-informed synthetic dataset and simulation for DSS training images, and (4) the evaluation of the performance of the deep learning approach for various mask configurations.

A wide range of phenomena, from explosive transients to active galactic nuclei, exhibit variability at radio wavelengths on timescales of a few years. Characterizing the rate and scale of variability in the radio sky can provide keen insights into dynamic processes in the Universe, such as accretion mechanics, jet propagation, and stellar evolution. We use data from the first two epochs of the Very Large Array Sky Survey to conduct a census of the variable radio sky. Approximately $3,600$ objects are found to significantly vary in brightness during the $\sim2.5\,$ years between observations. For compact sources whose mean flux density across the two epochs, $\mu_{S}$, is brighter than $20\,$mJy, $\approx 5\,$% show brightness variations $>30\,$%, rising to $\approx 9\,$% at $\mu_{S}>300\,$mJy. Most of the VLASS variables have multiwavelength properties consistent with blazars and quasars, including those with the largest absolute changes in flux density. The largest fractional changes in brightness are exhibited by galactic sources. We discuss our results, including some of the more interesting and extreme examples of variable radio sources identified, as well as future research directions.

Odd Radio Circles (ORCs) are a new class of distinct radio objects that has recently been discovered. The origin of these features is yet unclear because their peculiar properties are a challenge for our current understanding of astrophysical sources for diffuse radio emission. In this work we test the feasibility of major mergers in galaxy groups as a possible formation channel for ORCs. By modeling the assembly of a massive galaxy group with a final virial mass of $M_{200}\sim 10^{13}\, \rm M_\odot$ in a magnetohydrodynamic zoom-in simulation with on-the-fly cosmic ray treatment, we are able to derive the X-ray and radio properties of the system self-consistently and compare them to observations. We show that the X-ray properties for the simulated system are agreeing with characteristics of observed galaxy groups in the regarded mass range, legitimating the comparison between the radio properties of the simulated halo and those of observed ORCs. A major merger between two galaxies in the simulation is triggering a series of strong shocks in the circumgalactic medium, which in unison are forming a ring if the line of sight is perpendicular to the merger axis. The shock is rapidly expanding in radial direction and quickly reaches the virial radius of the halo. This formation channel can hence readily explain the morphology and large extent of ORCs. However, the inferred radio luminosity of these features is lower than for observed counterparts, while the degree of polarization seems to be systematically overpredicted by the simulation. Fossil cosmic ray populations from AGN and stellar feedback might be necessary to explain the full extent of the radio properties of ORCs, since diffusive shock acceleration was the only source term for non-thermal electrons considered in this work.

We present Hubble Space Telescope (HST) imaging of Pegasus V and Pisces VII, along with a re-analysis of the archival imaging of Pegasus W, and Jansky Very Large Array (VLA) neutral gas (HI) observations of all three. These three ultra-faint dwarfs (UFDs) are all within the Local Group in the approximate direction of M31. The VLA observations place stringent upper limits on their HI content, with all having $M_\mathrm{HI} < 10^4\;\mathrm{M_\odot}$. As the red giant branches of these UFDs are sparsely populated, we determined distances from the HST photometry of horizontal branch (HB) stars in comparison to a fiducial HB population (from M92), with all three falling in the range 0.7-1 Mpc. Using a new Python-based star formation history (SFH) fitting code (based on StarFISH), we derive SFHs of all three UFDs. As found previously, the best fit SFH for Pegasus W includes significant star formation well beyond the end of reionization, while the SFHs calculated for Pegasus V and Pisces VII are consistent with them having quenched shortly after reionization. These findings for the latter two objects indicate that, like those in the vicinity of the Milky Way, lower mass UFDs in the vicinity of M31 likely quenched at early times.

The formation and evolution of galaxies are intricately linked to the baryon cycle, which fuels star formation while shaping chemical abundances within galaxies. Investigating the relationship between star formation and metallicity for large samples of galaxies requires expensive IFU surveys or sophisticated tools to analyze grism data. Here we analyze JWST NIRISS slitless grism data using Sleuth, a tool that forward models and infers spatially resolved physical properties from grism data, including observations from JWST NIRISS/NIRCam and future grism data like that from the Roman Space Telescope. Sleuth enables extraction of high-quality emission line maps from slitless spectra, overcoming contamination and spatially varying stellar populations, which previously limited such studies. Utilizing Sleuth with data from the CAnadian NIRISS Unbiased Cluster Survey (CANUCS), we investigated the relationship between metallicity and star formation in the star-forming clumps of galaxies at 0.6 < z < 1.35. We analyzed a sample of 20 galaxies, extracted high-quality emission line maps with Sleuth, and analyzed, in detail, the spatially resolved properties of star-forming clumps. Using $H\alpha$, [SII], and [SIII] emission line maps, we examined the spatially resolved metallicities, ionization, and star formation rates of our sample. Our findings reveal that these star-forming clumps show lower metallicities ($\sim$ 0.1 dex) than their surrounding galactic environments, indicating a metallicity dilution of 20 $\%$ within the clumps' gas. Our analysis indicates that these clumps exhibit intensified star formation and reduced metallicity, likely due to the inflow of metal-poor gas. These clumps illustrate the dynamic relationship between star formation and chemical enrichment within galaxies.

Stars in the Milky Way disk exhibit a clear separation into two chemically distinct populations based on their [$\alpha$/Fe] ratios. This $\alpha$-bimodality is not a universal feature of simulated disk galaxies and may point to a unique evolutionary history. A popular explanation is the two-infall scenario, which postulates that two periods of substantial accretion rates dominate the assembly history of the Galaxy. Thanks to recent advances in stellar age measurements, we can now compare this model to more direct measurements of the Galaxy's evolutionary timescales across the disk. We run multi-zone galactic chemical evolution models with a two-infall-driven star formation history and compare the results against abundance patterns from APOGEE DR17, supplemented with stellar ages estimated through multiple methods. Although the two-infall scenario offers a natural explanation for the $\alpha$-bimodality, it struggles to explain several features of the age--abundance structure in the disk. First, our models generically predict a massive and long-lasting dilution event, but the data show that stellar metallicity is remarkably constant across much of the lifetime of the disk. This apparent age-independence places considerable restrictions upon the two-infall parameter space. Second, most local metal-rich stars in APOGEE have intermediate ages, yet our models predict these stars should either be very old or very young. Some of these issues can be mitigated, but not completely resolved, by pre-enriching the accreted gas to low metallicity. These restrictions also place limits on the role of merger events in shaping the chemical evolution of the thin disk.

We present Hubble Space Telescope (HST) FUV spectra and light curves of the magnetic cataclysmic variable (CV) LAMOST J024048.51+195226.9 (J0240), the second known CV propeller. The five consecutive HST orbits span a full 7.34 hour binary orbital period. We detect a 24.939 $\pm$ 0.006 s FUV modulation, confirming that J0240 contains the fastest spinning white dwarf (WD) in a CV. A high N V/C IV emission line ratio is considered an indicator of a recent episode of thermal time-scale mass transfer. The observed ratio in J0240 is higher than seen in typical magnetic CVs, but far less than observed in the only other confirmed propeller, AE Aquarii (AE Aqr). We also find that J0240 is significantly less luminous than AE Aqr during both low- and high-flux states. Around orbital phase 0.5, the Si IV emission line displays a P-Cygni absorption profile likely related to the gas accelerated in the propeller. We derive new mass-dependent temperature limits for the surface temperature of the WD of T $\leq$ 11,000-15,000 K. This temperature is low enough to allow for WD core crystallization, which may be linked to magnetism in WDs, particularly those in CVs.

We study the morphology of hundreds of simulated central galaxies in the stellar mass range $M_\star=10^{7.5} \rm - 10^{11}~$\msun\, from the FIREbox cosmological volume. We demonstrate that FIREbox is able to predict a wide variety of morphologies, spanning from disk-dominated objects to spheroidal galaxies supported by stellar velocity dispersion. However, the simulations predict a strong relation between morphology (degree of rotational support) and stellar mass: galaxies comparable to the Milky Way are often disk-dominated while the presence of stellar disks mostly vanishes for dwarfs with $M_\star <10^9 ~$\msun. This defines a ``morphology transition'' regime for galaxies with $10^9 <M_\star/\rm{M_\odot}< 10^{10}$ in which disks become increasingly common, but below which disks are rare. We show that burstiness in the star formation history and the deepening of the gravitational potential strongly correlate in our simulations with this transition regime, with disks forming in objects with lower levels of burstiness in the last $\sim 6$ Gyr and halos with mass $\sim 10^{11} ~ \rm{M_{\odot}}$ and above. While observations support a transition towards thicker disks in the regime of dwarfs, our results are in partial disagreement with observations of at least some largely rotationally supported gas disks in dwarfs with $M_\star < 10^9$\msun. This study highlights dwarf morphology as a fundamental benchmark for testing future galaxy formation models.

We study two classes of single-field inflationary models - a generalization of the alpha-attractor and the alpha-Starobinsky model - and examine their compatibility with current observational data from Planck, ACT DR6, and BAO measurements from DESI DR2. Our analysis focuses on the reheating phase that follows inflation, characterized by the equation-of-state parameter omega_re, the reheating temperature T_re, and the number of e-folds N_re. We use a semi-analytical approach based on an equation linking inflationary dynamics to reheating, allowing us to compute the inflaton value at horizon crossing phi_k and other related cosmological quantities. We consider different decay channels for the inflaton: gravitational, Yukawa, and scalar. We are particularly interested in studying these models in the r-n_s and T_re-n_s planes, especially in regions close to the P-ACT-LB2 combination, which is the area most distant from the Planck data. To do this, we explore a wide range of values for the model parameters and show the graphs where the closest approximation to the P-ACT-LB2 region occurs. Other authors have already carried out related work; where there is overlap, our results are consistent with those obtained by other means.

We present a multi-epoch spectroscopic study of the broad absorption line (BAL) quasar J115636.82+085628.9 (z(em) = 2.1077), based on five spectra spanning nearly two decades in the observer's frame. This source exhibits remarkable variability in both low-ionization (LoBAL: Al III and Mg II) and high-ionization (HiBAL: C IV and Si IV) absorption features. For the first time, we detect the emergence and subsequent disappearance of LoBAL troughs at high velocities (~20,000 kms$^{-1}$), coinciding with the strengthening and weakening of the corresponding HiBAL absorption. The C IV BAL profile extends from ~6,700 kms$^{-1}$ to a conservative upper limit of 30,000 kms$^{-1}$ and is composed of narrow, variable absorption features embedded within a broad, smooth envelope. Both C IV and Si IV BAL troughs exhibit dramatic equivalent width (EW) changes, among the most extreme reported to date. Notably, these EW variations are strongly anti-correlated with continuum flux changes inferred from optical photometric light curves. We interpret this variability as the result of a new absorbing flow transiting into our line of sight, increasing the shielding of a more distant, pre-existing outflow and giving rise to transient LoBAL absorption. This scenario supports a unified picture in which LoBAL and HiBAL features arise from similar outflow structures, with observed differences governed primarily by line-of-sight column densities consistent with previous findings.

With the launch of the Laser Interferometer Space Antenna (LISA), we will be able to estimate the sky position, luminosity distance (d$_{L}$), chirp mass, and mass ratio for detected merging massive black hole binary (MBHB) systems. LISA's uncertainties on these estimates will evolve over time, and enable electromagnetic (EM) follow-up observations as early as a month from coalescence. In this paper, we create a framework that takes simulated LISA parameter estimates for sky localisation and d$_{L}$ for a MBHB and performs a census of matching EM galaxies, or candidate host galaxies. We used this framework to investigate these parameter estimates for simulated MBHB systems with masses of $3\times10^{5}$, $3\times10^{6}$, and $1\times10^{7}$M$_{\odot}$ at redshifts of $0.3$ and $0.5$ and used these parameters to select matching galaxies from archival Sloan Digital Sky Survey (SDSS) photometry. We found that the number of candidate host galaxies for a simulated MBHB system at a redshjft of $0.3$ and $1$ hour from coalescence ranged from tens to thousands. After coalescence, we found that our census numbers dropped to zero for all systems when considering median constraints most likely due to survey limitations. For a MBHB with mass $3\times10^{6}$M$_{\odot}$ at $1$ hour from coalescence, increasing the redshift from $0.3$ to $0.5$ or varying the sky position within the SDSS footprint resulted in the number of EM counterparts increasing by approximately a factor of $2$.

By fitting the tilt in the path of the Orphan-Chenab Stream (OCS), we conclude that the current mass of the Large Magellanic Cloud (LMC) within 30 kpc is $4.7$ - $5.1 \times 10^{10}$ M$_\odot$. We note that the tidal radius of the LMC of this mass is 16.9 kpc, indicating that our measured mass approximates the current bound mass of the LMC. Previous measurements of the LMC mass based on fitting the observed path of the OCS through the Milky Way (MW) halo reported the total mass of the LMC. We show that because the closest approach of the LMC to the OCS, where the gravitational perturbation of the stream path is the highest, is about 20 kpc, the mass of the LMC outside of 30 kpc is not constrained and depends entirely on the assumed radial profile at large radius. Our best-fit total mass varies between $4.5 \times 10^{10}$ and $2.2 \times 10^{11}$ M$_\odot$ or more, depending on the presumed radial profile of the LMC. We also show that previous measurements of the mass of the LMC that used a particle-spray method to simulate the path of the OCS suffered from systematic error because they assumed that all particles were stripped from the dwarf galaxy at the tidal radius; N-body simulations show that particles are actually released from a range of distances from the center of mass of the OCS. In contrast, the choice of MW potential has little effect on the estimated LMC mass from the OCS.

Cassiopeia A (Cas A) is the youngest known core-collapse supernova remnant (SNR) in the Galaxy and is perhaps the best-studied SNR in X-rays. Cas A has a line-rich spectrum dominated by thermal emission and given its high flux, it is an appealing target for high-resolution X-ray spectroscopy. Cas A was observed at two different locations during the Performance Verification phase of the XRISM mission, one location in the southeastern part (SE) of the remnant and one in the northwestern part (NW). This paper serves as an overview of these observations and discusses some of the issues relevant for the analysis of the data. We present maps of the so-called ``spatial-spectral mixing'' effect due to the fact that the XRISM point-spread function is larger than a pixel in the Resolve calorimeter array. We analyze spectra from two bright, on-axis regions such that the effects of spatial-spectral mixing are minimized. We find that it is critical to include redshifts/blueshifts and broadening of the emission lines in the two thermal components to achieve a reasonable fit given the high spectral resolution of the Resolve calorimeter. We fit the spectra with two versions of the AtomDB atomic database (3.0.9 and 3.1.0) and two versions of the SPEX (3.08.00 and 3.08.01*) spectral fitting software. Overall we find good agreement between AtomDB 3.1.0 and SPEX 3.08.01* for the spectral models considered in this paper. The most significant difference we found between AtomDB 3.0.9 and 3.1.0 and between AtomDB 3.1.0 and SPEX 3.08.01* is the Ni abundance, with the new atomic data favoring a considerably lower (up to a factor of 3) Ni abundance. Both regions exhibit significantly enhanced abundances compared to Solar values indicating that supernova ejecta dominate the emission in these regions. We find that the abundance ratios of Ti/Fe, Mn/Fe, \& Ni/Fe are significantly lower in the NW than the SE.

We present the 2025 release of the spectral synthesis code Cloudy, highlighting significant enhancements to the scope and accuracy of the physics which have been made since the previous release. A major part of this development involves resolving the Lyman $\alpha$ line into $j$-resolved fine-structure doublets, making Cloudy of use to the X-ray community. On this front, we have also updated inner-shell ionization line energies and incorporated the 1 keV feature commonly observed in X-ray binaries. Additionally, we update our in-house database, Stout, for the carbon isoelectronic sequence, improving Cloudy microphysical calculations for all wavelengths. We have also extended the molecular network by adding new silicon-bearing species, titanium-related reactions, and phosphorus-containing molecules, enhancing Cloudy's ability to model the complex chemistry relevant to rapidly growing field of exoplanet atmospheres. Finally, we outline future developments aimed at maximizing the scientific return from the current and upcoming generation of observatories, including XRISM, JWST, Roman, the Habitable Worlds Observatory (HWO) and NewAthena.

The proper motions (PMs) of M31 and M33 are key to understanding the Local Group's dynamical evolution. However, measurement discrepancies between Gaia blue and red samples, regarding whether the transverse velocity is remarkable, introduce significant ambiguity. In this work, we remeasure the systemic PMs of M31 and M33 using massive supergiant stars from Gaia Data Release 3. Clean disk tracers are selected via color-color diagrams, with foreground contaminants removed through kinematic and astrometric cuts. We identify the discrepancy in M31's blue and red samples as arising from systematic differences between Gaia's 5-parameter (5p) and 6-parameter (6p) astrometric solutions. The 6p solution, applied to sources lacking accurate color information, relies on a pseudo-color approximation, leading to lower precision and larger uncertainties. Two key limitations of the 6p solution are: 1) degraded astrometric accuracy for very red sources (GBP - GRP > 2.6); 2) significant PM zero-point offsets. In our sample, red sources are dominated by the 6p solution, while blue sources include a substantial fraction of 5p sources; this mismatch drives the observed discrepancy. By excluding extreme red sources and calibrating PM zero-points separately for 5p and 6p sources using background quasars, we reduce the discrepancy, bringing blue and red measurements into agreement within 1 sigma. We ultimately report the most robust Gaia-based PMs using high-quality 5p sources. For M31, we obtain ({\mu}_{\alpha}*, {\mu}_{\delta})_M31 = (45.9 +/- 8.1, -20.5 +/- 6.6) {\mu}as/yr, consistent with, but more precise than, the HST result. For M33, we find ({\mu}_{\alpha}*, {\mu}_{\delta})_M33 = (45.3 +/- 9.7, 26.3 +/- 7.3) {\mu}as/yr, agreeing with VLBA measurement within 1.5 sigma. These results support a first infall scenario for M33.

Interstellar medium widely exists in the universe at multi-scales. In this study, we introduce the {\it Multi-scale Decomposition Reconstruction} method, an equation-based model designed to derive width maps of interstellar medium structures and predict their volume density distribution in the plane of the sky from input column density data. This approach applies the {\it Constrained Diffusion Algorithm}, based on a simple yet common physical picture: as molecular clouds evolve to form stars, the density of interstellar medium increases while their scale decreases. Extensive testing on simulations confirms that this method accurately predicts volume density with minimal error. Notably, the equation-based model performs comparably or even more accurately than the AI-based DDPM model(Denoising Diffusion Probabilistic Models), which relies on numerous parameters and high computational resources. Unlike the "black-box" nature of AI, our equation-based model offers full transparency, making it easier to interpret, debug, and validate. Their simplicity, interpretability, and computational efficiency make them indispensable not only for understanding complex astrophysical phenomena but also for complementing and enhancing AI-based methods.

GW231123 is a merger of two black holes (BHs) whose inferred masses exceed $100\;{\rm M}_\odot$ typically; they are the most massive BHs among those discovered by gravitational wave (GW) observations. We examine if GW231123-like events can be formed from isolated Population (Pop) III binary stars by means of binary population synthesis calculations. We find that Pop III isolated binary stars can create GW231123-like events at a rate large enough to explain the discovery of GW231123, if two conditions are satisfied. First, Pop III stars evolve with inefficient convective overshooting, and second the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ rate is $2\sigma$ lower than the standard value. On the other hand, GW190521, which is the most massive BHs in Gravitational Wave Transient Catalog 3, can be formed from isolated Pop III binary stars even if the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ rate is the standard value. We reveal that the discovery of GW231123 is progressively putting constraints on possible parameter ranges of single star evolution models, assuming that all the GW events are formed through isolated binary evolution.

Heartbeat stars (HBSs) are ideal laboratories for studying the formation and evolution of binary stars in eccentric orbits and their internal tidal interactions. We present 42 new HBSs discovered based on TESS photometric data. Their light curves are modeled by using a corrected version of Kumar et al.'s model or the PHOEBE binary model code. Tidally excited oscillations (TEOs) are detected in ten systems, with most pulsation phases can be explained by the dominant being $l=2$, $m=0$, or $\pm2$ spherical harmonic. For TIC 156846634, the harmonic with large deviation ($>3\sigma$) can be expected to be a traveling wave or nonadiabatic. The $n$ = 16 harmonic in TIC 184413651 may not be considered as a TEO candidate due to its large deviation ($>2\sigma$) and lower amplitude. Moreover, TIC 92828790 shows no TEOs but exhibits a significant gamma Doradus pulsation. The eccentricity-period (e$-$P) relation also shows a positive correlation between eccentricity and period, as well as the existence of orbital circularization. The Hertzsprung-Russell diagram shows that TESS HBSs have higher temperatures and greater luminosities than Kepler HBSs. This significantly enhances the detectability of massive HBSs and those containing TEOs. Currently, the search for HBSs using TESS data has become a research focus, and these intriguing objects may serve as valuable additions to the TESS HBS catalog.

We present a comprehensive, energy-resolved study of cosmic-ray muon anisotropy using 12 years (2011-2023) of data from the IceCube Neutrino Observatory, comprising 7.92 x 10^11 events in the 13 TeV to 5.3 PeV energy range. Dividing the spectrum at log-scale energy 5 GeV, we contrast low- and high-energy anisotropy features via sidereal modulation, angular profiles, Fourier analysis, and full-sky HEALPix mapping. Gaussian and power-law fits to energy distributions are evaluated using chi-squared, reduced chi-squared, and Bayesian Information Criterion. Results show strong dipolar and large-scale anisotropy at low energies, likely due to geomagnetic and atmospheric effects, while high-energy muons display weaker, more localized structures consistent with reduced scattering and source-related anisotropy. Energy distributions are well fit by Gaussians, especially in the 6.5 to 100 bin, validating IceCube's reconstruction at PeV scales. These findings confirm energy-dependent anisotropy and support cosmic-ray diffusion models.

The vertical settling of dust grains in a circumstellar disk, characterized by their scale height, is a pivotal process in the formation of planets. This study offers in-depth analysis and modeling of the radial scale height profile of dust grains in the HL Tau system, leveraging high-resolution polarization observations. We resolve the inner disk's polarization, revealing a significant near-far side asymmetry, with the near side being markedly brighter than the far side in polarized intensity. This asymmetry is attributed to a geometrically thick inner dust disk, suggesting a large aspect ratio of $H/R \ge 0.15$. The first ring at 20 au exhibits an azimuthal contrast, with polarization enhanced along the minor axis, indicating a moderately thick dust ring with $H/R \approx 0.1$. The absence of the near-far side asymmetry at larger scales implies a thin dust layer, with $H/R < 0.05$. Taken together, these findings depict a disk with a turbulent inner region and a settled outer disk, requiring a variable turbulence model with $\alpha$ increasing from $10^{-5}$ at 100 au to $10^{-2.5}$ at 20 au. This research sheds light on dust settling and turbulence levels within protoplanetary disks, providing valuable insights into the mechanisms of planet formation.

Corotating interaction regions (CIRs) are compressions that form in stellar winds when streams of different speeds collide. They form an Archimedean spiral around the star and can compress any exoplanetary magnetospheres they impact. They may also steepen into shocks capable of accelerating particles to high energies. We model the frequency and strength of these CIRS for stars of spectral types F-M. We show that the minimum radius, $r_{CIR}=\Delta \phi u_{slow}/\Omega$, at which CIRs form varies strongly with the rotation rate (and hence age) of the star. For some exoplanets, such as those in Earth or Mars orbits, CIRs can form within the exoplanet's orbit at all stellar rotation rates, depending on the angular size of the fast wind segment ($\Delta \phi$). These exoplanets will experience CIR impacts at all stellar ages. However, for closer-in orbits such as Mercury or Venus, this may only be the case at higher stellar rotation rates. Both the frequency and impact of CIRs depend on the stellar rotation rate. For exoplanets with $P_{orbit}\gg P_*$, CIR impacts lasting for a time $\Delta t$ raise the exoplanetary outflow rate by a factor $R$. If $P_*\leq N\Delta t$ the CIR pulses overlap in time, whereas if $N\Delta t < P_* \leq N\Delta t(R+1)$, the planet experiences discrete pulses of compression and relaxation and the CIR-related outflow is more than 50$\%$ of the total. For $P_* > N\Delta t(R+1)$ the pulses are less frequent, and contribute less than $50\%$ of the total outflow.

Characterizing the atmospheres of exoplanets and brown dwarfs is crucial for understanding their atmospheric physics and chemistry, searching for biosignatures, and investigating their formation histories. Recent advances in observational techniques, combining adaptive optics with high-resolution spectrographs, have enabled detailed spectroscopic analysis for directly imaged faint companions. In this paper, we report an atmospheric retrieval on the L-type brown dwarf HR 7672 B using a near-infrared high-contrast high-resolution spectrograph, REACH (Y, J, H band, $R\sim100,000$), which combines SCExAO with IRD at the Subaru Telescope. Our model, developed based on the ExoJAX spectrum code, simultaneously accounts for several factors, including the presence of clouds in the L dwarf's atmosphere as well as contamination from the host star's light and telluric absorption lines in the observed spectra. Our analysis identified H2O and FeH as the primary absorbers in the observed J- and H-band spectra. Additionally, the observed features were reproduced with a model that includes cloud opacity, assuming an optically thick cloud at the pressure $P_\mathrm{top}$. The resulting temperature at the cloud top pressure suggests the potential formation of clouds composed of TiO2, Al2O3, or Fe. This study is the first science demonstration for faint spectra obtained by REACH, providing a foundation for future investigations into the atmospheres of exoplanets and brown dwarfs.

Symbiotic stars, which generally comprise a red giant and an accreting white dwarf, are excellent laboratories to understand mass transfer in wide binaries, with application to a wide family of systems. One of the fundamental questions is how mass is transferred from the red giant to the white dwarf. We use interferometric measurements made with the VLTI/PIONIER instrument, combined with Gaia data, to measure the radius of the giant in seven symbiotic systems. We further place the giants in the H-R diagramme, which allows us to estimate their mass and to show that they are all very evolved and likely on the asymptotic giant branch. We compare our measured giant radii to their Roche-lobe radius and show that, except for ZZ CMi, all giants are well within their Roche lobe and that mass transfer likely takes place via stellar wind. Our interferometric data provide further evidence that the giant in ZZ CMi (nearly) fills its Roche lobe. Our conclusions are still hampered by the poor characterisation of some of the giants or their binary orbit, and we encourage the community to make an effort to provide these.

Ultra-fast outflows (UFOs) with mildly relativistic velocities are frequently observed in active galactic nuclei (AGNs). The line-force-driving mechanism is often taken as a potential mechanism for driving UFOs. Due to the line-force-driven winds moving at mildly relativistic velocities, the special relativistic effects become this http URL are two special relativistic effects: one is the influence of the disc rotation on the radiation field; the other is the radiation-drag effect. We wish to study the influence of the special relativistic effects on the line-force-driven winds, and we performed numerical simulations to investigate this http URL find that the line-force-driven winds are significantly weakened when the special relativistic effects are considered. Compared with the case without special relativistic effects, when special relativistic effects are considered the winds are closer to the disc surface, the maximum speed of winds is reduced by $\sim$20 percent--70 percent, and the mass outflow rate and the kinetic power is significantly reduced.

The Central Molecular Zone (CMZ), located in the centre of the Milky Way, is a roughly cylindrical structure of molecular gas extending up to parsecs around the supermassive black hole Sagittarius A*. The average H2 ionisation rate in the CMZ is estimated to be 2e-14 s-1, which is 2-3 orders of magnitude higher than anywhere else in the Galaxy. Due to the high gas density in this region, electromagnetic radiation is rapidly absorbed, leaving low-energy cosmic rays (CRs) as the only effective ionising agents. Hence, a high CR density has been invoked to explain such high ionisation rates. However, a corresponding excess in gamma rays, which would result from interactions of high-energy CRs, has not been observed. This suggests that the supposed excess exists only in the low-energy CR spectrum. To constrain this unknown low-energy component, we first derive the high-energy CR injection spectra using gamma-ray and radio data, to which we add various low-energy components. We then propagate these injection spectra by numerically solving the CR transport equation using a Crank-Nicolson scheme. Testing multiple CR injection scenarios, we find that the energy required to sustain the observed ionisation rates is excessively high in every case. We conclude that CRs cannot be the exclusive ionising agents in the CMZ.

Dark100 is a planned array of six telescopes, using the Panoramic Search for Extraterrestrial Intelligence (PANOSETI) telescope system. It will operate as an imaging atmospheric Cherenkov telescope array, with a telescope design and array layout optimized for accessing gamma rays with tens of TeV to PeV energies. The science goals of Dark100 include the search for ultra-heavy dark matter, observations of Galactic Pevatrons, and the search for ultra-fast optical transients. Rejection of background cosmic rays is key to the sensitivity of the array. We present a first study of gamma/hadron separation based on simulated gamma rays and protons, focusing on the impact of the hadronic background models used in CORSIKA.

We report the detection of Ly${\alpha}$ in CANUCS-LRD-z8.6, a recently discovered AGN at z = 8.63 by Tripodi et al. (2024), in new NIRSpec/MSA G140H/F070LP observations. We detect broad Ly${\alpha}$ emission (FWHM $= 1540 \pm 260$ km/s) near the systemic velocity, which suggests a large ionizing bubble considering that the universe is almost fully neutral at the redshift. Through Ly${\alpha}$ line-shape modeling assuming a Stromgren sphere, we find a large bubble radius, $R_b = 1.5^{+0.3}_{-0.2}$ pMpc, and a moderately high Ly${\alpha}$ escape fraction, $f_{esc} = 11 \pm 3$ %. The intrinsic line width is inferred to be broad ($2200 \pm 280$ km/s), likely originating in the broad-line region. Existing data indicate that CANUCS-LRD-z8.6 is within a mild overdensity, $\delta = 1.9^{+2.9}_{-0.7}$, suggesting that other galaxies in its proximity might have contributed to the formation of the bubble. The high N IV]${\lambda}$1488 / C IV${\lambda}$1548 and N IV]${\lambda}$1488 / O III]${\lambda}$1661 line ratios measured in existing NIRSpec/PRISM data indicate nitrogen enrichment in this metal-poor, low-luminosity AGN. The spectroscopic features are overall similar to other nitrogen-rich galaxies discovered in the literature, such as GN-z11 and GHZ2/GLASSz12. This suggests that CANUCS-LRD-z8.6 may represent one of the evolutionary phases of those nitrogen-rich galaxies.

Propagating fluctuations within accretion disks are known to induce multi-wavelength variability across diverse timescales. While these fluctuations have been widely invoked to explain rapid timing phenomena within the inner disk region in the frequency domain, observational signatures of outer-disk fluctuations propagating in the time domain remain sparse. Here, we present an analysis of observations by the Hard X-ray Modulation Telescope (HXMT) during the 2023 outburst of the newly discovered low-mass black hole X-ray binary Swift J1727.8-1613. Follow-up, high-cadence monitoring reveals intense variability in disk emission, attributable to fluctuations in the accretion rate. These disk fluctuations exhibit damped amplitudes and shortened flare periods. We interpret these features as observational evidence of fluctuations originating at and propagating from large radii, supported by fitting the disk light curves with a propagating fluctuation model. Furthermore, we propose that a plausible mechanism driving these fluctuations is the cyclical propagation of heating and cooling fronts in the context of the disk instability model. This work bridges theoretical predictions with time-domain observations, offering critical insights into the dynamic processes governing accretion disks.

The morphology and kinematics of atomic Hydrogen (HI) gas in galaxies are influenced by both local and large scale cosmic environments. Differences in galaxy environment and interactions can leave distinct signatures in HI asymmetry, offering insight into environmental effects on galaxy evolution. We investigate the role of environment on HI asymmetries in galaxies located in two contrasting structures: the Ursa Major (UMa) group and the Perseus Pisces (PP) filament. We analyze HI 21cm imaging from the WSRT and the VLA, homogenized in resolution for fair comparison. Asymmetries in global profiles and column density maps are measured using criteria established in arXiv:2205.00675 and compared to those of mock galaxies presented in the same study. The PP volume hosts a higher fraction of galaxies with asymmetric global HI profiles (33%) compared to UMa (9%). Likewise, 46% of PP galaxies have morphological HI asymmetries above 0.5 at a threshold of 15 x 10^19 cm^-2, compared to 13% in UMa. The greater column density sensitivity of the UMa data enables detection of lopsided features and asymmetry measurement down to 5 x 10^19 cm^-2. We also identify simulated galaxies with unphysical asymmetries likely caused by unrealistic feedback. In both volumes, stellar and HI morphological asymmetries are uncorrelated. Global profile and morphological asymmetries are also found to be uncorrelated, consistent with previous results.

The analysis of precise Gaia DR3 astrometry in the LMC region has revealed asymmetric patterns in the bar quadrupole and the disc outskirts of the LMC in-plane velocity maps. We aim to quantify the asymmetries detected in the LMC radial and residual tangential velocity maps, and determine whether they are generated naturally due to the LMC's interaction with the SMC. We analyse the velocity maps of different simulations from the KRATOS suite of N-body simulations of the LMC-SMC-MW system, proposing a new methodology to quantify the kinematic asymmetry in the bar and the outskirts of the disc. We also transform the KRATOS simulations into Gaia mock catalogues to confirm that the asymmetric signature in the LMC is not an effect of observational uncertainties. In addition, we investigate the possibility of a classification bias in the neural network classifier of the Gaia optimal sample. In the KRATOS simulations of the LMC and SMC interaction, the dynamical effect of the SMC passages produces a displacement of the bar and asymmetries in the LMC velocity maps. By comparing the velocity maps of mock catalogues of the future Gaia data releases DR4, DR5 and GaiaNIR, we find that the asymmetric signature in the bar quadrupole is independent of observational errors. We thereby confirm that it is a consequence of the interaction of the LMC with the SMC. We also find a classification bias in the neural network classifier, indicating that the outer disc asymmetry observed in the optimal sample is artificial. The analysis of the KRATOS simulations reveals that the interaction of the LMC with the SMC can generate asymmetric patterns in the velocity field. In the case of the Gaia DR3 LMC velocity maps we conclude that the bar quadrupole asymmetry is directly correlated with the SMC interaction, while the outer disc asymmetry is an artefact of the classifier for the optimal sample.

Beyond deepening our understanding of the formation, growth, and evolution of supermassive black holes, it is crucial to uncover the role of feeding and feedback processes from growing black holes (i.e., active galactic nucleus; AGN) in shaping the cosmic ecosystem. Such studies include understanding the dynamics of gas flows in the interstellar (ISM), circumgalactic (CGM), intracluster (ICM), and intergalactic media (IGM). As the output of a sub-group in Habitable Worlds Observatory (HWO) AGN Working Group, this Science Case Development Document (SCDD) proposes to use future HWO observations to solve the following questions. Which mechanism is dominant in triggering inflows/outflows through feedback? How is AGN activity triggered, and is it associated with circumnuclear star formation and what is the overall effect of AGN feedback on star formation (SF)? In AGN feedback, which mode is more influential and does AGN feedback operate similarly or differently in the local universe and at high redshift? To answer these questions, this SCDD proposes to use potential HWO observations as follows. Resolve and characterize the spatial distribution of ionized and cold/warm molecular gas, especially those in inflows/outflows; Explore the spatial coupling and potential stratification of multi-phase inflows/outflows on different physical scales and their resolved and global correlations with AGN and/or SF activities; Investigate whether corresponding outflows/jets induce shocks and/or fluctuations that trigger or suppress the formation of molecular clouds and hence new stars. Specifically, HWO's capabilities will enable us to achieve the above scientific goals while existing facilities lack the required combination of high-throughput ultraviolet (UV) and near-infrared (NIR) integral field unit (IFU) capabilities with simultaneously sufficient spatial resolution and sensitivity.

With excellent spectral and angular resolutions and, especially, sensitivity, the JWST allows us to observe infrared emission lines that were previously inaccessible or barely accessible. These emission lines are promising for evaluating the physical conditions in different galaxies. Based on {\sc MAPPINGS V} photoionization models, we systematically analyze the dependence of over 20 mid-infrared (mid-IR) emission lines covered by the Mid-Infrared Instrument (MIRI) onboard JWST on the physical conditions of different galactic environments, in particular narrow line regions (NLRs) in active galactic nuclei (AGN). We find that mid-IR emission lines of highly ionized argon (i.e., [Ar~{\small V}]7.90,13.10) and neon (i.e., [Ne~{\small V}]14.32,24.32, [Ne~{\small VI}]7.65) are effective in diagnosing the physical conditions in AGN. We accordingly propose new prescriptions to constrain the ionization parameter ($U$), peak energy of the AGN spectrum ($E_{\rm peak}$), metallicity ($\rm 12+log (O/H)$), and gas pressure ($P/k$) in AGN. These new calibrations are applied to the central regions of six Seyfert galaxies included in the Galaxy Activity, Torus, and Outflow Survey (GATOS) as a proof of concept. We also discuss the similarity and difference in the calibrations of these diagnostics in AGN of different luminosities, highlighting the impact of hard X-ray emission and particularly radiative shocks, as well as the different diagnostics in star-forming regions. Finally, we propose diagnostic diagrams involving [Ar~{\small V}]7.90 and [Ne~{\small VI}]7.65 to demonstrate the feasibility of using the results of this study to distinguish galactic regions governed by different excitation sources.

We evaluate the reliability of CNEOS-derived ephemerides of fireball events given the absence of the underlying data. We analyzed 18 events that have both (i) sufficient satellite information to derive orbits and (ii) ground-based observational counterparts. We quantify the uncertainties on these calibrated events using the orbital similarity criterion D_D. We also examine the velocity components imbalance and identify discriminants that can indicate the accuracy of an event. We identify two groups in the CNEOS database. CNEOS data produces ephemeris determinations with D_D<0.1 for fireballs reported either (i) after late 2017 or (ii) with impact energies above 0.45 kt with 74-78% of events having D_D=0.03$\pm$0.02, while ~11% show D_D<0.008. Our statistical test confirms these two parameters as the only reliable discriminants that, when combined, explain the two accuracy groups. Daylight, z-velocity component, low altitude, long duration, and latitude might also indicate errors, although the limited dataset may obscure correlations. No clear discriminants are identified for more restrictive D_D cut-offs. We provide estimates of orbital uncertainties for calibrated events. The hyperbolic fireball subset in the CNEOS database appears as an outlier in the velocity imbalance test. Our results confirm that the fidelity of CNEOS fireball data improved significantly from 2018, likely due to the deployment of next-generation space sensors, and show a growing number of high-velocity events. Hyperbolic candidates should be interpreted with caution, as their velocities and inclinations likely reflect measurement errors. Accuracy constraints remain limited by the dataset size, as evidenced by the lack of statistically significant dependence on duration, preventing strong conclusions from being drawn.

Fast radio bursts (FRBs) are enigmatic millisecond-duration signals which encode otherwise unattainable information on the plasma which permeates our Universe, providing insights into magnetic fields and gas distributions. Here we report the discovery of FRB 20240304B originating at redshift 2.148 +/- 0.001 corresponding to just 3 billion years after the Big Bang. FRB 2024030 was detected with the MeerKAT radio telescope and localized to a low-mass, clumpy, star forming galaxy using the James Webb Space Telescope. This discovery doubles the redshift reach of localized FRBs and probes ionized baryons across ~80% of cosmic history. Its sightline, intersecting the Virgo Cluster and a foreground group, reveals magnetic field complexity over many gigaparsec scales. Our observations establish FRB activity during the peak of cosmic star formation and demonstrate that FRBs can probe galaxy formation during the most active era in cosmic time.

This study proposes a unified framework comprising two complementary approaches to constrain three functional forms of $f(T,B)$ gravity, namely the linear, quadratic, and general power law models, by jointly utilizing early and late Universe observations. First, we impose bounds on deviations in the weak interaction freeze-out temperature, informed by the latest measurements of the primordial helium-4 mass fraction. Second, we incorporate direct Hubble parameter data, $H(\mathcal{z})$, obtained from Cosmic Chronometers in the redshift range $0.07\le\mathcal{z}\le2.0$, to trace the expansion history of the Universe. By minimizing a combined chi-square statistic across both datasets, we derive the best-fit values and confidence intervals for each model parameter. The joint analysis significantly refines the parameter constraints compared to methods based solely on Big Bang Nucleosynthesis, thereby offering a more robust test of $f(T,B)$ gravity across cosmic epochs. The results support the viability of torsion-based modifications to General Relativity and provide a consistent methodology for future evaluation using upcoming observational data.

Temperature programmed desorption (TPD) is a well-known technique to study gas-surface processes, and it is characterized by two main quantities: the adsorbate binding energy and the pre-exponential factor. While the former has been well addressed in recent years by both experimental and computational methods, the latter remains somewhat ill-defined, and different schemes have been proposed in the literature for its evaluation. In the astrochemistry context, binding energies and pre-exponential factors are key parameters that enter microkinetic models for studying the evolution over time of the chemical species in the universe. In this paper, we studied, by computer simulations, the effect of different pre-exponential factor models using water, ammonia, and methanol adsorbed on amorphous and crystalline ices as test cases: specifically, the one most widely used by the astrochemical community (Herbst-Hasegawa), the models provided by Tait and Campbell, and an extension of the Tait formulation including the calculation of the vibrational partition function. We suggest the methods proposed by Tait and Campbell that provide TPD temperature peaks within 30 K of each other while avoiding demanding quantum mechanical calculations, as they are based on tabulated data. Finally, when the explicit inclusion of the vibrational partition function is needed, we propose a cost-effective strategy to include all the thermal contributions in the partition functions without the need for performing a full vibrational calculation of the whole system.

We present a framework for the computation of effective stellar yields that accounts for a mixed population of binary and single stars under an adjustable mix of binary evolution settings: the binary fraction, the accretion efficiencies of winds, Roche-lobe overflow, and supernovae. We emphasise the critical need for more complete yield coverage of the binary nucleosynthesis and evolution, without which the ability to make accurate predictions on the true role of binarity on GCE calculations is hamstrung. We also provide clear guidelines for future stellar modelling works to ensure their results are maximally useful to the wider community. We compute effective stellar yields using detailed binary stellar yields accounting for binary induced mass-loss from a solar-metallicity donor star. We study the effect of varying the binary mixture and accretion efficiencies, and consider a range of models for the treatment of accreted material on the secondary in detail. In the absence of detailed binary yields for the secondary, we put forth a model for the composition of accreted material that preserves the signature of the primary's nuclear processing within the post-mass-transfer secondary yields. Among the binary parameters, we find that the binary fraction, which determines the ratio of binary and single star systems, has the most significant effect on the effective stellar yields, with widespread impact across most isotopes. In contrast, varying the accretion efficiencies produces comparatively minor changes. We also find that the binary fraction has a significant influence on the logarithmic elemental abundance ratios relative to H present in the effective yield; this impact is largest for the lower-mass primaries.

The rotational evolution of a strongly magnetized neutron star (NS), accreting or isolated, is driven by external torques of different nature. In addition to the torques, even the tiniest deformations of the NS crust can affect its rotation through asymmetries in its inertia tensor. Several factors may be responsible for the deformations, including strong magnetic fields, internal stresses, or local heating. The main effect produced by the deformations is the so-called free precession: the motion of the rotational axis with respect to the crust. We consider the evolution of a triaxially deformed isolated NS with a strong dipolar magnetic field for a broad range of parameters, taking into account the magnetic field decay. We show that the combination of pulsar torques and free precession results in a considerable broadening of the distribution of magnetic obliquity angles (the angle between the magnetic and rotational axes) and creates a population of objects where the rotational axis does not align with the magnetic axis at all but enters a limit-cycle regime. The combination of free precession and magnetic torques can also explain the observed distribution in pulsar braking indices by creating a periodic oscillation in the magnetic obliquity.

The Planck measurement of the cosmic microwave background (CMB) has established the $\Lambda$-cold-dark-matter ($\Lambda$CDM) model as the concordant model along with other observations. However, recent measurements of baryon acoustic oscillations (BAO) from the Dark Energy Spectroscopic Instrument (DESI) collaboration have renewed the matter fraction $\Omega_\mathrm{m}$ tension between DESI-$\Lambda$CDM and Planck-$\Lambda$CDM. Directly reconciling this CMB-BAO tension with a dynamical DE in Chevallier-Polarski-Linder (CPL) parametrization seems to imply a crossing of the equation-of-state through $w=-1$ at low redshifts. In this letter, we will illustrate with a string-theory-motivated model that, when the DM non-minimally couples to gravity via a quintessence field, a misidentification with the $w_0w_a$CDM model would exactly fake such a crossing behavior, while the coupled quintessence never crosses $w=-1$ but behaves as a standard CDM in the early Universe and approaches a cosmological constant in the late Universe. Such a non-minimal coupling is preferred over $3\sigma$ confidence level. The worsened $\Omega_\mathrm{m}$ tension and $S_8$ tension in the $w_0w_a$CDM model are also resolved in our model.

Distant prograde orbits around the Moon exhibit remarkable potential for practical applications such as cislunar surveillance activities and low-energy transfers due to their instability. Previous works on transfers from circular low Earth orbit to distant prograde orbits mainly focused on construction methods based on dynamical structures, lacking a comprehensive analysis of the solution space of this transfer scenario. This paper investigates the solution space and identifies families of transfers from a 167 km circular low Earth orbit to a 1:1 distant prograde orbit. In particular, grid search and trajectory continuation are performed to construct these transfer trajectories. Initial guesses of the transfers are selected in the 1:1 distant prograde orbit through a backward propagation strategy and are then corrected to satisfy specified constraints. Based on the obtained solutions, a linear predictor is derived to predict more feasible solutions and a predictor-corrector continuation method is used to extend the solution space. Twelve transfer families are identified, most of which are new or previously underexplored. The distributions of construction parameters and transfer characteristics of these twelve families are analyzed and discussed, showing which families are applicable to which types of specific practical missions. Comparison between the obtained solution and solution developed by previous works is further performed to imply the effects of the selection of dynamical model on transfer construction.

Crystalline ice in Earth's atmosphere can produce spectacular phenomena due to orientation-dependent attenuation, such as sun dogs and halos, providing diagnostics of the external processes acting on the aerosol grains. Crystalline mineral aerosols, such as quartz (SiO$_2$) and enstatite/forsterite (MgSiO$_3$/Mg$_2$SiO$_4$), have long been predicted to form in hot Jupiter atmospheres with JWST MIRI LRS verifying the existence of crystalline quartz observationally. Due to the strong horizontal winds ($\sim$ 1 - 5 km s$^{-1}$) and small aerosol grains ($<1$ $\mu$m) found in hot Jupiter atmospheres, we show that aerosols could be mechanically aligned with the winds. We then derive directional-dependent optical properties of quartz, enstatite, and forsterite and model transmission and emission spectra assuming random and mechanically aligned orientations, finding that the orientation of all three crystalline aerosols can impart $\geq$ 100 ppm differences in observed spectra (8 - 12 $\mu$m). We run retrievals on JWST MIRI LRS transmission and emission data of WASP-17b and find that directionality alone cannot physically explain the transmission data, pointing towards polymorphs or insufficient lab data, and find weak hints of directionality (1.0 - 1.3$\sigma$) in the emission data. This work demonstrates the power of JWST MIRI LRS in detecting aerosol directionality with future observations, and a technique by which to probe how aerosols interact with atmospheric dynamical processes. To foster the exploration of aerosols in exoplanet data, the open-source code POSEIDON has been updated (v1.3.1) to include 144 new directional and temperature aerosols with precomputed optical properties, alongside new aerosol models.

Spectroscopic and photometric variability is widespread among O-type supergiants. It is linked to various phenomena affecting the star and its circumstellar environment, thereby providing direct information concerning them. To investigate such connections, we decided to revisit the prototypical O7.5 Iabf supergiant HD 192639. High-cadence spectroscopic monitoring was performed simultaneously with intensive space-borne photometric observations. The data were analysed with several methods to characterise the variability. Besides the usual stochastic, low-frequency photometric variability, our observations reveal the presence of recurrent - but transient - modulations on a timescale of about five days. The same signal is present in the spectroscopic data and was already seen two decades ago. This stability suggests that this timescale corresponds to the stellar rotation. Furthermore, our observations unveil, for the first time, an unusually strong dimming event in the light curve associated with absorption and emission changes in H I and He I lines. This unprecedented trough corresponds to an episodic ejection of a rather large amount of mass (its column density being comparable to that of the steady wind). While rare, such an event could hint at an overlooked aspect of mass loss in massive stars.

The long-term retention of substantial atmospheres in close-in exoplanets presents a major challenge to classical hydrodynamic escape theory, which predicts rapid mass loss under intense stellar irradiation. In this work, we propose a fully classical, interior-driven suppression mechanism based on thermoelastic contraction of the planetary mantle. By incorporating pressure- and temperature-dependent elastic deformation into the structural evolution of the planet, we demonstrate that radial contraction can lead to measurable increases in surface escape velocity. We analytically derive a modified escape condition and introduce a dimensionless suppression index Xi that quantifies the extent to which internal mechanical response inhibits atmospheric loss. Numerical simulations across a wide parameter space show that volumetric strain values in the range 0.005 to 0.01 can enhance escape velocities by up to 10 percent, leading to a reduction in energy-limited escape rates by over 50 percent. When applied to warm mini-Neptunes such as GJ 1214b, K2-18b, and TOI-270c, the model successfully accounts for their persistent atmospheres without invoking exotic stellar conditions or chemical outliers. Our results indicate that planetary elasticity, often neglected in escape models, plays a first-order role in shaping the atmospheric evolution of close-in worlds. The theory yields specific observational predictions, including suppressed outflow signatures and radius anomalies, which may be testable with JWST, ARIEL, and future spectroscopic missions.

We investigate the clustering of Primordial Black Holes (PBHs) within the framework of Excursion Set Theory (EST). The EST formalism is extended to compute the joint probability of forming PBH pairs within a clustering distance, based on two stochastic trajectories with a shared history. Our results show that an enhanced power spectrum not only increases the formation of PBHs in specific mass ranges but also enhances their clustering probability. We find a one-to-one correspondence between the blue-tilted spectral index and the mass ranges in which PBHs form and cluster. Additionally, we demonstrate that the clustering probability decreases asymptotically with increasing clustering distance, while a higher critical density threshold (barrier) leads to a suppression of clustering abundance.

The increasing availability of high-quality optical and near-infrared spectroscopic data, as well as advances in modelling techniques, have greatly expanded the scientific potential of spectroscopic studies. However, the software tools needed to fully exploit this potential often remain fragmented across multiple specialised packages, requiring scripting skills and manual integration to handle complex workflows. In this paper we present SPAN (SPectral ANalysis), a cross-platform, Python-based Graphical User Interface (GUI) software that unifies the essential tools for modern spectral analysis within a single, user-friendly environment. While SPAN can be used with a variety of spectroscopic targets, its primary focus is the analysis of unresolved galaxy spectra. SPAN allows users to extract 1D spectra from FITS images and datacubes, perform spectral processing (e.g. Doppler correction, continuum modelling, denoising), and carry out detailed analyses, including line-strength measurements, stellar and gas kinematics, and stellar population studies, using both built-in routines and the widely adopted pPXF algorithm for full spectral fitting. It runs natively on Windows, Linux, macOS, and Android, and is fully task-driven, requiring no prior coding experience. We validate SPAN by comparing its output with existing pipelines and literature studies. By offering a flexible, accessible, and well integrated environment, SPAN simplifies and accelerates the spectral analysis workflow, while maintaining scientific accuracy.

The structure of accretion flows in low-luminosity active galactic nuclei (AGN) at low Eddington ratios (~10^-2 to 10^-3) are poorly-understood, and can be probed using the spectral energy distributions (SEDs) of faded changing-look (CL) quasars. Previous results using single-epoch X-ray and rest-frame UV observations of samples of faded CL quasars suggest that their SED properties at low Eddington ratios display similarities to X-ray binaries fading from outburst. However, more robust tests demand multi-epoch observations that can trace the temporal behavior of the SEDs of individual AGN at low Eddington ratios. Here, we perform this test, by obtaining a second epoch of UV and X-ray observations of a sample of three faded CL quasars with bolometric Eddington ratios of <10^-3, using a combination of contemporaneous HST UV imaging, Chandra X-ray observations, and optical spectroscopy. We find that all three CL quasars varied in luminosity, and their optical-to-X-ray spectral indices alpha_OX all individually display a negative (harder-when-brighter) correlation with Eddington ratio. This SED evolution is also often observed in X-ray binaries at low Eddington ratios, and adds to the growing evidence that AGN accretion flows behave analogously to X-ray binaries across all accretion states.

We report observations of the ultra-high-energy gamma-ray source LHAASO J2108$+$5157, utilizing VERITAS, HAWC, \emph{Fermi}-LAT, and \textit{XMM-Newton}. VERITAS has collected $\sim$ 40 hours of data that we used to set ULs to the emission above 200 GeV. The HAWC data, collected over $\sim 2400$ days, reveal emission between 3 and 146 TeV, with a significance of $7.5~\sigma$, favoring an extended source model. The best-fit spectrum measured by HAWC is characterized by a simple power-law with a spectral index of $2.45\pm0.11_{stat}$. \emph{Fermi}-LAT analysis finds a point source with a very soft spectrum in the LHAASO J2108+5157 region, consistent with the 4FGL-DR3 catalog results. The \textit{XMM-Newton} analysis yields a null detection of the source in the 2 - 7 keV band. The broadband spectrum can be interpreted as a pulsar and a pulsar wind nebula system, where the GeV gamma-ray emission originates from an unidentified pulsar, and the X-ray and TeV emission is attributed to synchrotron radiation and inverse Compton scattering of electrons accelerated within a pulsar wind nebula. In this leptonic scenario, our X-ray upper limit provides a stringent constraint on the magnetic field, which is $\lesssim 1.5\ \mu$G.

To understand better the polarized radiative transfer near the surface of rotating massive stars that remain nearly spherically symmetric, we use plane-parallel stellar atmosphere models to explore the unique opportunity presented by the Ohman effect. This effect refers to the predicted variation in linear polarization across a rotationally broadened absorption line, due to the interaction of that line with the spatially varying continuum polarization across the face of a strongly scattering photosphere, such as found in hot stars. Even if the rotation is weak enough for the star to remain spherically symmetric, the Ohman effect persists because differential absorption induced by the rotational Doppler shift of the line breaks the symmetry that would otherwise cancel the continuum polarization in the absence of that line. Neglecting rotational distortion effects, the net polarization across the line vanishes, yet resolved line profiles display a telltale triple-peak polarization pattern, with one strong polarization peak at line center and two smaller ones in the line wings at a position angle that is rotated 90 degrees from the line center. The far ultraviolet (FUV) is emphasized because both the polarization amplitude and the specific luminosity are greatest there for photospheres with effective temperatures between about 15,000 and 20,000K. There is a high density of spectral lines in the FUV, leading to a rich "second stellar spectrum" in linear polarization (analogous to the "second solar spectrum") that is made observable with stellar rotation. Polarizations at the level of 0.1% to 1% are achievable across individual lines for a wide variety of B-type stars. We highlight the prospects for accessing the unique information encoded in the Ohman effect with future moderate-resolution spaceborne spectropolarimetric missions in the FUV.

Recent LHAASO observations hint at potential spectral hardening around 20 TeV in M87's very high energy (VHE) emission, suggesting a possible new radiation component. In this work, we construct averaged multiwavelength SEDs by combining data from Chandra and Swift-UVOT/XRT covering the same period as the LHAASO detection to investigate the origin of this feature. We test several radiation mechanisms, including the pp interaction, proton synchrotron emission, photomeson process and two-zone leptonic model. We find that only the pion decay gamma rays in pp interactions can interpret this feature in the framework of the one-zone model. With analytical analysis, we prove that proton synchrotron emission cannot generate a hard spectrum above 0.17~TeV. For photomeson model, it requires an emission zone compressed near the Schwarzschild radius of the central supermassive black hole, incompatible with broadband optical-GeV spectral constraints. In addition, the two-zone leptonic model also emerges as a viable alternative.

The origin of certain proton-rich isotopes in the solar system, particularly $^{92,94}{\rm Mo}$ and $^{96,98}{\rm Ru}$, has been a long-standing puzzle. A promising explanation is the $\nu p$-process, which is posited to operate in the neutrino-driven outflows that form inside core-collapse supernovae after shock revival. Recent studies have identified several relevant physical effects that influence the yields of this process. The impact of General Relativity (GR) on the $\nu p$-process yields, however, remains unexplored. In this work, we perform a comparative analysis of the time-integrated yields of the $p$ nuclei up to $A \lesssim 105$ in Newtonian and fully GR neutrino-driven outflows, using a detailed model of a time-evolving outflow profile. The two main GR effects are the gravitational shift of neutrino energies and post-Newtonian corrections to the gravitational potential. These effects together suppress the production of seed nuclei, significantly boosting the $\nu p$-process yields in our 18 $M_\odot$ progenitor model. Most of the production of the crucial $^{92,94}{\rm Mo}$ and $^{96,98}{\rm Ru}$ $p$ isotopes in this model occurs in an optimal time window, 1-3 seconds after shock revival. Interestingly, the same does not apply to the shielded isotope $^{92}{\rm Nb}$, a large fraction of which is produced in the subsequent ejecta. The impact of GR on this isotope is especially large, with its final abundance boosted by a factor of 25 compared to a Newtonian calculation. In our 12.75 $M_\odot$ model, an additional GR effect is observed: the outflow transitions to the supersonic regime several seconds into the explosion, causing the yields to drop. This study quantifies the important role GR effects play in the $\nu p$-process and provides guidance for identifying optimal conditions in future self-consistent supernova simulations.

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission is a CubeSat Space Weather mission, designed to operate in a Sun-Earth Distant Retrograde Orbit (DRO) at more than 10 million km from Earth. HENON will embark payloads tailored for Space Weather (SWE) observations: a high-resolution energetic particle radiation monitor, a Faraday cup, and a magnetometer, enabling quasi-real-time monitoring of interplanetary conditions in deep space. HENON has multiple objectives, such as demonstrating CubeSat capabilities in deep space, including long-duration electric propulsion with periodic telemetry and command, and robust attitude control for deep-space operations. It will pave the way for a future fleet of spacecraft on DROs, providing continuous near real-time measurements for SWE forecasting. This paper focuses on the mission analysis performed for phases A and B, with the main goal of defining a baseline transfer trajectory to a heliocentric DRO in co-orbital motion with Earth. The proposed transfer leverages a rideshare opportunity on a mission escaping Earth gravity field, most likely one headed toward the Sun-Earth L2 region, and relies exclusively on on-board electric propulsion to reach deep space, making it a pioneering demonstration of this approach and the technology. Under appropriate assumptions on the electric propulsion system performance, spacecraft mass, and propellant budget, it is shown that the HENON target DRO can be reached in about one year, accounting also for periodic interruptions of thrusting to allow for telemetry, tracking, and command.

Cross-correlations between a gravitational tracer of dark matter and the contribution to the unresolved gamma-ray background (UGRB) from the radiation produced by the annihilation of the particles responsible for the dark matter, have been established as a powerful tool to investigate the particle physics nature of dark matter. Cross-correlations of the UGRB with galaxy catalogs, cluster catalogs and weak lensing have indeed been measured. In this paper we study statistical techniques that could improve the sensitivity of the cross-correlation techniques on the bounds that can be set to the particle dark matter physical properties. The two methods that we investigate are the application of a Wiener filter and the exploitation of the full multi-tracer information. After identifying the optimal strategies, we show that the adoption of a Wiener filter in the cross-correlation analysis can improve the sensitivity to the dark matter annihilation rate by a factor of 2/2.5 as compared to the standard analysis where no filter is applied. The inclusion of the full multi-tracer information can improve the sensitivity up to a factor of 5 for dark matter masses below about 50 GeV, the Wiener filter remaining the best option for heavier dark matter.

Hot subdwarf B (sdB) stars are post-main-sequence stars of high temperature and gravity. Approximately 30$\%$ of sdBs exhibit stable pressure and/or gravity-mode pulsations, which can be used via the timing method to test for companion stars and determine their orbital solutions. We used short cadence data from the Transiting Exoplanet Survey Satellite (TESS) to search for previously undiscovered companions to sdBs. In this paper, we focus on searching for companions with orbital periods shorter than 13.5$\,$d which are detectable within one sector of TESS data (about 27$\,d$). The timing method requires that we derive pulsation frequencies in subsets of data significantly shorter than the periods we are searching for, which we set at 0.5 to 1.5$\,$d. We investigated ten sdB stars with previously detected p-mode pulsations for which at least one p-mode pulsation remains detectable with a signal-to-noise ratio (S/N) $>$ 4 within data subsets of duration 0.5 - 1.5$\,$d. We find that two (TIC$\,$202354658 and TIC$\,$69298924) of these ten sdB stars likely have white dwarf companions and set limits on companion masses for the other eight sdB stars.

Rotating black holes are known to launch relativistic jets and accelerate particles provided they accrete a magnetized plasma. However, it remains unclear how the global magnetic field orientation affects the jet powering efficiency. Here, we propose the first kinetic study of a collisionless plasma around a Kerr black hole that is embedded in a magnetic field inclined with respect to the black hole's spin axis. Using three-dimensional general-relativistic particle-in-cell simulations, we show that while oblique magnetic field configurations significantly reduce the jet power, particle acceleration remains highly efficient regardless. This suggests that black holes producing a weak jet could still be bright sources of nonthermal radiation and cosmic rays.

A sample of objects with steep and ultra-steep spectra was prepared from radio sources of the Cold experiment surveys conducted on the RATAN-600 radio telescope. It formed the basis for the Big Trio program for searching for distant radio galaxies. With the advent of high-sensitivity, high-angular-resolution radio sky surveys, as well as deep optical and infrared surveys, it became possible to conduct additional studies of the sample. We refined the morphology and spectra of continuous radio emissions from radio galaxies. A detailed study of the morphological features of the sample sources revealed that 4 of the sample sources are formed by close radio sources with a distance of about 60 kpc between the parent galaxies. 8% of the radio sources demonstrate a restart of activity in the radio range, 20% of the sources are in an environment that leads to the deformation of the lobes, 11% are young sources and 2% are fading. A high percentage of sources with a variability index greater than 3 is associated with a large difference in the angular resolution of the compared TXS and VCSS surveys, as well as an underestimated flux density for some double sources in the latter survey. Comparison of spectral indices obtained from old and new data showed that in the studied sample the share of sources with steep spectra has significantly decreased. Most likely, this is due to the addition of low-frequency GLEAM data, although for some radio sources a possible evolution of the continuum spectrum over an interval of several decades is not excluded -- a shift towards low frequencies.

M31N 2017-01e is the second-fastest recurrent nova known, with a recurrence period of 2.5 years in the Andromeda Galaxy (M31). This system exhibits a unique combination of properties: a low outburst amplitude ($\sim3$ magnitude), starkly contrasting with known recurrent novae (typically $\geq 6$ magnitudes), and a very fast evolution ($t_{2}\sim 5 $ days). Its position coincides with a bright variable source ($\mathrm{M_V \sim -4.2,\, B-V= 0.042}$) displaying a 14.3 day photometric modulation, which has been suggested as the likely progenitor. We present a multi-wavelength analysis of optical and UV data spanning quiescence and the 2019 and 2024 outbursts. Archival high-resolution imaging reveals two nearby faint sources within $5^{\prime\prime}$ of the proposed nova system, which we identified as unrelated field stars. Color analysis and spectral energy distribution fitting suggest the progenitor is likely an early-type star. Combined with archival spectra consistent with a B-type star with H$\alpha$ in emission, this points to the quiescent counterpart being a Be star with a circumstellar disc. We propose that M31N 2017-01e arises from a rare Be-WD binary, where the WD accretes from the decretion disk of its companion, explaining its rapid recurrence, low-amplitude outbursts, and unusual quiescent luminosity and color. This analysis highlights M31N 2017-01e as a compelling outlier among recurrent novae, suggesting a distinct accretion mechanism and evolutionary path that challenges the prevailing paradigm.

We present the [OIII]$_{88\mu \text{m}}$ spectral scan results from the ALMA Large Program REBELS (Reionization Era Bright Emission Line Survey). The generally high luminosity of [OIII]$_{88\mu \text{m}}$ and ALMA's Band 7 efficiency motivated its use for line scans of REBELS targets at $z>8$. Spectral scans of four sources covered 326.4-373.0 GHz ($z=8.10$-9.39), reaching [OIII]$_{88\mu \text{m}}$ luminosities of $\mathrm{\sim7.6\times10^8\ L_{\odot}}$ ($5\sigma$) for a FWHM of 400 km s$^{-1}$. No credible lines are detected for the four targets. For REBELS-04, the non-detection is unexpected given the $\geq92\%$ coverage of the redshift likelihood distribution and its estimated SFR of 40 $\text{M}_{\odot}\ \text{yr}^{-1}$. Possible explanations for the faint [OIII]$_{88\mu \text{m}}$ emission (assuming a FWHM of 100 km s$^{-1}$) include high ISM densities ($>n_{\text{crit}} \approx 510\ \text{cm}^{-3}$) and low ionization parameters ($\mathrm{log_{10}\ U_{ion}\lesssim -2.5}$). For REBELS-37, a subsequent detection of [CII]$_{158\mu \text{m}}$ ($z=7.643$) confirmed it lay outside our scan range. For REBELS-11 and REBELS-13, it remains unclear if the non-detection is due to the depth of the line scan or redshift coverage. REBELS-04 and REBELS-37 show significant ($\geq3.8\sigma$) dust continuum emission in Band 7. If the photometric redshift of REBELS-04 is accurate, i.e., $z_{\mathrm{phot}}=8.57^{+0.10}_{-0.09}$ or $z_{\mathrm{phot}}=8.43^{+0.10}_{-0.10}$ accounting for additional neutral hydrogen in the circumgalactic medium, REBELS-04 would constitute the most distant dust-detected galaxy identified with ALMA to date. Additional Band 6 dust observations of REBELS-37 constrain the shape of the far-IR SED, ruling out cold dust temperatures ($\lesssim28$ K) at $3\sigma$. Further insight into these galaxies will require spectroscopic redshifts and deeper multi-band dust observations.

Isotopic properties of meteorites provide evidence that multiple dust trap or pressure bumps had to form and persist in the inner Solar System on a timescale of millions of years. The formation of a pressure bump at the outer edge of the gap opened by Jupiter blocks particles drifting from the outer to the inner disk. This is not enough to preserve dust in the inner disk. However, in low viscosity disks, under specific condition on the gas cooling time, massive planets can also open secondary gaps, separated by density bumps, inward of the main gap. The majority of studies have been done in two dimensional equatorial simulations with prescribed disk cooling. Recent results have shown that including the treatment of radiation transport is key to determine the formation of secondary gaps. We extend previous studies to three dimensional disks including radiative effects and we also consider non ideal MHD effects, in disks with prescribed cooling time. We perform three dimensional hydrodynamical numerical simulations with self consistent treatment of radiative effects and including the magnetic field with non ideal Ohmic and Ambipolar effects. We show that in a disk with low bulk viscosity and consistent treatment of radiative effects, planetary masses close to the pebble isolation mass as well as a Jupiter massive planet open multiple gaps. In the presence of non ideal MHD effects multiple gaps and rings are also formed by a Jupiter massive this http URL conclusion the formation of multiple gaps and rings inside the planetary orbit is crucial to preserve dust reservoirs. Such reservoirs are pushed towards the inner part of the disk during Jupiter runaway growth and are persistent after Jupiter's growth. Multiple dust reservoirs could therefore be present in the inner Solar System since the formation of Jupiter's solid core if the disk had low-viscosity.

Near-Earth objects (NEOs) have the potential to cause extensive damage and loss of life on Earth. Advancements in NEO discovery, trajectory prediction, and deflection technology indicate that an impact could be prevented, with sufficient warning time. We derive an impact frequency of NEOs 140m and larger, using the NEOMOD2 NEO population model and JPL Horizons. We then place that frequency in context with other preventable causes of death; allowing for comparison between a planet-wide event and individual events that cause fatalities such as car crashes and carbon monoxide poisoning. We find that the chance of a $>140$ m asteroid hitting the Earth is more likely than the chance of an individual being struck by lightning.

In current cosmological simulations, the radiative transfer modules generally rely on the M_1 approximation, which has some glaring flaws related to its fluid-like behaviour, such as spurious pseudo-sources and loss of directionality when radiation fronts from different directions collide. P_n, another moment-based model used in other fields of physics, may correct these issues. We aim at testing out P_n in an astrophysical setting and compare it to M_1, in order to see if it can indeed correct M_1's flaws. Also, we want to use P_n's solutions to better pinpoint M_1 errors. We implement a P_n radiation transport method and couple it to a photo-thermo-chemistry module to account for the interaction of ionising radiation with the Hydrogen gas, and benchmark it using tests for radiative transfer models comparison in astrophysics as defined in arXiv:astro-ph/0603199. We find that high order P_n (e.g. P_9) indeed correct M_1's flaws, while faring as well or even better in some aspects in the tests, in particular when directionality is important or colliding radiation fronts occur. By comparing P_9 and M_1 radiation fields in an idealised and cosmological test case, we highlight a new, thus far unreported artefact of M_1, the 'dark sombrero'. A dark sombrero appears as a spherical photon-deficit shell around the source. The photon density in dark sombreros can be underestimated by a factor up to 2-3. They occur in regions where a source's radiation field connects with that of another source or group of sources. These basic properties (position and amplitude) of the dark sombreros may depend on the sources' relative intensities, positions, spatial resolution, although we have not been able to test this in detail in this study.

3I/ATLAS, also known as C/2025 N1 (ATLAS), is the third known interstellar object to pass through our Solar System. We report serendipitous Transiting Exoplanet Survey Satellite (TESS) observations of 3I/ATLAS taken between 2025-05-07 and 2025-06-02,, 55 days prior to the discovery date (2025-07-01) and 14 days prior to the current earliest observation (2025-05-21). We retrieve the TESS pixel data, perform a robust background correction and use a data-driven approach to refine the object's ephemeris. We find a statistically significant offset between the target's observed and predicted positions and we show that this is dominated by uncertainty in the TESS World Coordinate System (WCS) rather than the ephemeris. 3I/ATLAS is too faint to be detected in the individual 200\,second TESS integrations, so we perform image stacking to improve detectability. After co-adding the TESS image data, we performed aperture and Pixel Response Function (PRF) photometry to create two light curves for 3I/ATLAS. Each light curve consists of 15 measurements with $\text{SNR}>3$, collected across two different TESS cameras during the 26\,days that the object was observed, but the PRF light curve is more robust against image noise. The PRF light curve in the TESS bandpass shows a gradual increase in brightness from $T_{\text{mag}} = 20.9 \pm 0.29$ to $T_{\text{mag}} = 19.57 \pm 0.15$. This is expected as 3I/ATLAS approaches the inner Solar System. This paper highlights the power of using TESS for Solar System science; by increasing the photometric observing baseline, future studies will be able to investigate the long-term behavior of 3I/ATLAS

We analyze photometry, spectra, and variability of over 100 faint X-ray sources in the globular cluster Terzan 5, using 737 ks of Chandra data. X-ray colors and spectral fitting allow clear separation of foreground sources (with less extinction than the cluster), quiescent low-mass X-ray binaries (qLMXBs), and sources with harder spectra. We identify 22 candidate qLMXBs, over twice that found in any other cluster. This is consistent with Terzan 5's stellar interaction rate, the highest among Galactic globular clusters. We do not see qLMXBs dominated by thermal emission below $L_X\sim10^{32}$ erg/s, though qLMXBs with stronger nonthermal emission could be missed. We find that more than 50 % of the qLMXB sources have neutron star thermal component contributing over 80 % of the total luminosity. We report an unusual spectral feature around 1.75 keV in the combined spectrum of Ter 5 X-3. The concentration of the qLMXBs within the cluster is consistent with that of a population of mass $1.46 \pm 0.14$ M$_\odot$. We identify secure X-ray counterparts to millisecond pulsars Terzan 5 ar and Terzan 5 at, using positional coincidence and orbital X-ray light curves matching those expected for spider pulsars.

We investigate numerically the energy flow and radiation efficiency of accreting neutron stars as potential ultraluminous X-ray sources (ULXs). We perform ten simulations {in radiative general relativistic magnetohydrodynamics (GRRMHD)}, exploring six different magnetic dipole strengths ranging from 10 to 100 GigaGauss, along with three accretion rates, 100, 300, and 1000 Eddington luminosity units. Our results show that the energy efficiency in simulations with a strong magnetic dipole of 100 GigaGauss is approximately half that of simulations with a magnetic dipole an order of magnitude weaker. Consequently, radiation efficiency is lower in simulations with stronger magnetic dipoles. We also demonstrate that outflow power increases as the magnetic dipole weakens, resulting in stronger beaming in simulations with weaker magnetic dipoles. As a result of beaming, simulations with magnetic dipole strengths below 30 GigaGauss exhibit apparent luminosities consistent with those observed in ULXs. As for the accretion rates, we find that higher accretion rates lead to more powerful outflows, higher kinetic efficiency, and lower radiation efficiency compared to those of lower accretion rate simulations.

As part of the JWST GTO program MINDS, we analyze the mid-infrared emission of three Class II binary systems: VW Cha, WX Cha, and RW Aur, to investigate the impact of stellar multiplicity on the chemistry and physics of their inner disk. We analyze the 1D spectrum from JWST/MIRI-MRS for primary and secondary disks separately, extracted by combining forward modeling with a theoretical PSF and aperture photometry. We modeled the molecular lines with 0D slab models. We interpret the results by comparing our JWST spectra to VLT/CRIRES+, Spitzer/IRS, and ALMA. Primary and secondary disks are dramatically different in their mid-infrared emission, with primary disks showing H2O-rich spectra, and secondary disks being mostly line poor to the sensitivity of our spectra. When comparing MIRI-MRS to Spitzer/IRS, we observe large variability in the line emission of VW Cha A, as well as in the continuum of RW Aur A. The disks around VW Cha BC and RW Aur B show evidence of ionizing radiation, and a further comparison with ALMA at high angular resolution dust continuum suggest that the spectrum of RW Aur B is well explained by its ~4 au cavity. All the systems show [Ne II] jet emission, and three of them also show spatially resolved emission structures in H2, likely originated by outflows and dynamical interactions. Many of the observed features in the primary disks, such as enhanced water emission, could be linked to the increased accretion and radial drift produced by dynamical disk truncation. However, additional mechanisms are needed to explain the large differences between primary and secondary disks, potentially inner disk substructures. This work is an example of the need for combining multiple facilities to fully understand the observations from JWST.

EDGES-3 is the third iteration of the EDGES experiment, designed to measure the predicted global absorption feature in the radio spectrum produced by neutral hydrogen gas at cosmic dawn, a critical observation determining when and how the first stars populated the universe. The EDGES-3 instrument has been redesigned to include both the analog and digital electronics within the antenna, allowing for in-situ calibration and removal of the lossy balun found in EDGES-2. EDGES-3 has been on multiple deployments in the past 4 years; to Oregon, Devon Island, Adak Island, and is currently installed and taking data in the outback of Western Australia. This paper provides an accounting of the challenges inherent in the detection of the global, cosmological 21-cm signal, the strategies EDGES employs to mitigate each of these challenges, a description of the instrument, and a report on the Western Australia deployment along with observational data.

The space-based CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed at developing new CubeSat missions. As part of CUSP's Phase B study, which began in December 2024 and will last one year, we present the current development status of the design solutions adopted for the mission's most critical multi-physics design drivers. These solutions have been formulated and applied to demonstrate compliance with system requirements at both the spacecraft and platform levels. In particular, we describe the mechanical design of each structural component, the results of static, dynamic finite element analyses, and a proposal for topological optimization of the interface between the platform and payload and some fixture for test, and the preliminary environmental testing campaign (e.g., vibration, shock) that will be carried out on a mechanical demonstrator.

We present the results of a spectroscopic investigation of two Large Magellanic Cloud globular clusters, NGC 1953 and NGC 1856. Both clusters have similar ages (250 and 300 Myr, respectively). Spectra were recorded with the Michigan/Magellan Fiber System located on the Magellan-Clay 6.5m telescope. Spectra were visually inspected to assess the presence of stellar H$\alpha$ emission lines attributed to B stars rotating close to breakup velocity (Be stars). High fractions of Be stars in the cluster typically indicate the presence of a large population of fast rotating stars, predicted by some models to explain the observed split and extended main sequence. There are numerous Be star candidates in NGC 1856, exhibiting weak but broad H$\alpha$ emission. However, only one such target was detected in NGC 1953. This stark contrast between the observed populations for NGC 1856 and NGC 1953 may suggest that cluster density plays a key role in determining the fraction of Be stars. These results provide essential constraints for the different scenarios attempting to explain the bimodal distribution of rotational velocities and the multiple populations of stars observed in globular clusters. The impact of stellar radial velocity and nebular emission on photometric measures is assessed through simulations relying on the spectra. These simulations suggest that photometric studies can under-estimate the fraction of H$\alpha$ emitters in a cluster, in particular for stars with relatively weak emission features. The results also show that nebular emission has minimal impact on the photometric H$\alpha$ excesses.

Precise measurements of neutron star masses and radii by the NICER mission impose important constraints on the nuclear equation of state. The most recent NICER measurement of PSR J0614-3329 reported an equatorial radius of $R_{eq} = 10.29^{+1.01}_{-0.86}$ km for a mass of $M = 1.44^{+0.06}_{-0.07} M_{\odot}$. Considering all the NICER measurements to date, we demonstrate using Bayesian hypothesis ranking that strange quark stars are preferred over all the physically motivated models of neutron stars compatible with this low radius. This provides a strong case for the possible existence of strange quark stars, suggesting that they should be considered among the population of compact stars during analyses of astrophysical data. Using a wide sample of equations of state, we report the nucleonic equations of state that best fit current observations and rule out one model of strange quark matter.

We present optical and near-infrared (NIR) spectroscopic observations of the nearby Type II supernova SN\,2024ggi from 250 and 420 days after the explosion. Comparing the evolution of the [\ion{O}{1}] at 6300, 6363 \textÅ doublet normalized to the continuum with spectral models from the literature, we estimate a progenitor star zero-age main-sequence mass ($M_{\mathrm{ZAMS}}$) of $\approx 14$ M$_\odot$. This value is consistent with $M_{\mathrm{ZAMS}}$ reported in the literature from independent methodologies. The nebular spectra are used to study the structure of the inner ejecta. The broad H$\alpha$ line has a full-width at half maximum (FWHM) of $\simeq 3900$ km s$^{-1}$, with small deviations from a symmetric Gaussian profile centred at zero velocity, and the [\ion{O}{1}] doublet is blue-shifted by $\approx -940$ km s$^{-1}$. In the NIR, the nebular spectra reveal double-peaked emission features of \ion{Mg}{1} and [\ion{Fe}{2}] lines, suggesting a bipolar distribution of intermediate mass and iron peak elements in the line-of-sight. Such a double-peaked feature in these NIR lines has not been previously reported. No corresponding asymmetries are observed in the hydrogen lines, suggesting that the asymmetry is mostly confined to intermediate mass and iron peak elements in the innermost core of the supernova ejecta. Additionally, we detect first-overtone carbon monoxide (CO) emission at $2.3$ $\mu$m from 250 to 319 days in the NIR.

The precise measurement of the muon anomalous magnetic dipole moment (AMDM) $a_\mu$ provides an opportunity for constraining the exotic interactions between muons mediated by new scalar or vector particles. Recent progress in both experimental measurements and theoretical predictions of the muon AMDM has reconciled the long-standing tension between them. Based on the latest result for the muon AMDM, $\Delta a_\mu =a^{\rm exp}_\mu-a^{\rm SM}_\mu= (38 \pm 63) \times 10^{-11}$, we derive updated constraints on exotic interactions between muons.

Considerable theoretical efforts have gone into expanding the reach of the QCD axion beyond its canonical mass--decay-constant relation. The $Z_\mathcal{N}$ QCD axion model reduces the QCD axion mass naturally, by invoking a discrete $Z_\mathcal{N}$ symmetry through which the axion field is coupled to $\mathcal{N}$ copies of the Standard Model. Before the QCD phase transition at temperature $T_{\rm QCD}$, the $Z_\mathcal{N}$ potential has a minimum at misalignment angle $\theta=\pi$. At $T_{\rm QCD}$, $\theta =\pi$ becomes a maximum; the axion potential becomes exponentially suppressed and develops $\mathcal{N}$ minima -- only one of which actually solves the strong CP problem. Before $T_{\rm QCD}$, $\theta$ relaxes towards $\pi$. After $T_{\rm QCD}$, the axion field starts from around the hilltop and may have sufficient kinetic energy to overcome the newly suppressed potential barriers. Such a field evolution leads to nonlinear effects via the self-interactions near the hilltop, which can cause the exponential growth of fluctuations and backreaction on the coherent motion. This behavior can influence the relic density of the field and the minimum in which it settles. We conduct the first lattice simulations of the $Z_{\mathcal{N}}$ QCD axion using ${\mathcal C}$osmo${\mathcal L}$attice to accurately calculate dark matter abundances and find nonlinear dynamics reduce the abundance by up to a factor of two. We furthermore find that the probability of solving the strong CP problem tends to diverge considerably from the naive expectation of $1/\mathcal{N}$.

We investigate dark matter (DM) interactions via spectroscopic signatures of energy injection in planetary environments. We develop a general framework to account for how DM energy injection signals depend on the DM spatial distribution, planetary structure, and DM energy deposition profile. We combine UV airglow data on the Solar System's gas giants from the Voyager and New Horizons flybys, and ionospheric measurements from AMS-02 and ELFIN CubeSat on Earth, with internal heat flow data from Cassini, Voyager, and terrestrial boreholes, to constrain DM-nucleon scattering across both heavy and light mediator scenarios. We show that Earth, gas giants, and ice giants probe complementary DM masses and mediator properties, and forecast the reach of a free-floating Super-Jupiter. These results establish planetary spectroscopy as a powerful and versatile probe of the dark sector, complementary to direct detection, cosmology, and collider searches.

Within the framework of spatially covariant theories, we propose a general model for dark energy (DE) in which the cosmological background and perturbations are independently controlled by different sets of coefficients, and the equation of state of DE is directly determined by two free functions of time from the Lagrangian. These properties allow to realize arbitrary background evolutions while avoiding ghost and gradient instabilities in linear perturbations. They also enable a more direct analysis of phantom crossing without having to first solve the background equations of motion. In this model, the sound speed of the scalar mode is scale-dependent and approaches infinity at large scale, so that the field becomes non-dynamical in the infrared (IR) limit. Even though this usually indicates a strong coupling issue, we speculate that this is avoided because the scalar degree of freedom becomes frozen not only at linear order but also at any higher order in IR limit. Given this characteristic large scales behavior, we dub the model \emph{Freezing Gravity}. On smaller scales, the scalar mode propagates with a finite speed of sound. The theory has a cut-off in energy, signaled by the pole in the speed of sound, when the effective Planck mass exceeds Planck mass.

We explore novel generation of genuine multipartite entanglement within gravitational particle production processes during inflationary stages. To this end, we focus on perturbative production mechanisms, considering a non-minimally coupled scalar inflaton field with quartic self-coupling potential and computing probability amplitudes arising from its gravitational interaction with background perturbations. The corresponding entanglement amount is quantified using the recently proposed Entanglement Distance, that provides a \emph{geometric interpretation of particle entanglement, in terms of the Fubini-Study metric}. We observe that, in the limit of negligible squeezing, the total amount of entanglement is dominated by the infrared cutoff scale, in agreement with previous studies analyzing the von Neumann entropy within bipartite scenarios. We then show that \emph{non-negligible multipartite entanglement signatures may emerge across inflation, even during the latest stages of slow-roll}, highlighting their dependence on inflationary momentum scales. Generalizations to regimes with non-negligible squeezing, cubic non-Gaussianities, additional spectator fields and possible observational signatures are also discussed.

Global Positioning System (GPS) satellites are essential for providing accurate navigation and timing information worldwide. Operating in medium Earth orbit (MEO), these satellites must maintain precise Earth-pointing attitudes to transmit signals effectively. This paper presents a comprehensive review of the operational dynamics, attitude determination and control systems (ADCS), and orbital insertion techniques for GPS satellites. We explore the integration of sensors and actuators, control algorithms, stabilization strategies, and the launch procedures required to deploy these satellites. Key equations related to orbital mechanics and attitude control are discussed, and references to recent technical literature are included.

We investigate the impact of one-loop radiative corrections in a non-supersymmetric model of hybrid inflation with a chaotic (polynomial-like) potential,$V(\phi) = V_0 + \lambda_p \phi^p$, in the light of the latest constraints from \textit{Planck} and \textit{Atacama Cosmology Telescope} (ACT) observations. Here, $V_0$ denotes the energy scale of inflation, and $\lambda_p$ is a coupling associated with the polynomial term of power $p$. These corrections can naturally arise from couplings of the inflaton to other matter fields, which also facilitate the reheating process. At the tree level, the predictions of such models for the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$ typically lie outside the current observational bounds. However, incorporating one-loop radiative corrections modifies the potential to, \[ V(\phi) = V_0 + \lambda_p \phi^p + A \phi^4 \ln (\phi/ \mu), \] where $A$ characterizes the strength of the inflaton's coupling to other fields, and \(\mu\) is an appropriate renormalization scale. This radiatively corrected potential can reconcile the model with the combined \textit{Planck}+ACT data over a suitable range of parameter space explored in this work. In particular, radiative corrections from fermionic loops ($A < 0$) suppress the tensor-to-scalar ratio $r$, while simultaneously yielding a red-tilted spectrum with $n_s < 1$, even for sub-Planckian field excursions. This brings the prediction in line with current observations, while still allowing for potentially detectable signatures of primordial gravitational waves. Furthermore, the inflaton's couplings enable successful reheating and naturally accommodate non-thermal leptogenesis, providing a unified framework for inflation and baryogenesis.

Cryogenic calorimeters for low-mass dark matter searches have achieved sub-eV energy resolutions, driving advances in both low-energy calibration techniques and our understanding of detector physics. The energy deposition spectrum of gamma rays scattering off target materials exhibits step-like features, known as Compton steps, near the binding energies of atomic electrons. We demonstrate a successful use of Compton steps for sub-keV calibration of cryogenic silicon calorimeters, utilizing four SuperCDMS High-Voltage eV-resolution (HVeV) detectors operated with 0 V bias across the crystal. This new calibration at 0 V is compared with the established high-voltage calibration using optical photons. The comparison indicates that the detector response at 0 V is about 30% weaker than expected, highlighting challenges in detector response modeling for low-mass dark matter searches.

Generative artificial intelligence (AI) excels at producing complex data structures (text, images, videos) by learning patterns from training examples. Across scientific disciplines, researchers are now applying generative models to ``inverse problems'' to infer hidden parameters from observed data. While these methods can handle intractable models and large-scale studies, they can also produce biased or overconfident conclusions. We present a solution with Frequentist-Bayes (FreB), a mathematically rigorous protocol that reshapes AI-generated probability distributions into confidence regions that consistently include true parameters with the expected probability, while achieving minimum size when training and target data align. We demonstrate FreB's effectiveness by tackling diverse case studies in the physical sciences: identifying unknown sources under dataset shift, reconciling competing theoretical models, and mitigating selection bias and systematics in observational studies. By providing validity guarantees with interpretable diagnostics, FreB enables trustworthy scientific inference across fields where direct likelihood evaluation remains impossible or prohibitively expensive.

We propose a simple and predictive setup that connects neutrino masses, dark matter (DM), and gravitational waves. A minimal lepton parity DM scenario is considered where the residual symmetry $(-1)^L$ from the type I seesaw acts as the dark parity $D=(-1)^{L+2j}$, ensuring DM stability without imposing any new symmetry. A singlet Majorana fermion $S$ with even lepton parity serves as the DM candidate, interacting via a real scalar $\sigma$ which is also even lepton parity. The scalar potential possesses an accidental $\mathcal{Z}_2$ symmetry, whose spontaneous breaking gives rise to unstable domain walls (DW) in the presence of explicit $\mathcal{Z}_2$ breaking terms allowed by the lepton parity. The subsequent DW annihilation generates a stochastic gravitational wave (GW) background potentially observable at different GW experiments.