Papers for Tuesday, Apr 08 2025

The observation of celestial objects is a fundamental activity in astronomy. Ground-based and space telescopes are used to gather electromagnetic radiation from space, allowing astronomers to study a wide range of celestial objects and phenomena, such as stars, planets, galaxies, and black holes. The European Southern Observatory (ESO) charges each night 83 kEUR (Milli et al. 2019), so the schedules of the telescopes are really important in order to optimize every second. Ground-based telescopes are affected by meteorological conditions, such as clouds, wind, and atmospheric turbulence. Accurate scheduling of observations in the presence of such uncertainties can significantly improve the efficiency of telescopes use and support from automated tools is highly desirable. In this paper, we study a mathematical approach for scheduling ground-based telescope observations under an uncertain number of clear nights due to uncertain weather and atmospheric conditions. The model considers multiple targets, uncertain number of nights, and various observing constraints. We demonstrate the viability and effectiveness of an approach based on stochastic optimization and reactive strategy comparing it against other methods.

As we prepare for the next planetary mission charged with finding life beyond Earth, the Astrobiology community must continue to improve its understanding of what constitutes a biosignature, through the use of planetary analog samples. The study of these collected and generated samples is expanding our knowledge of what constitutes habitable environments, what life is capable of, and importantly, how to make biosignature detections within compositionally complex samples - aiding in the development of life detection instrumentation. And yet the full potential of these samples remains untapped. While the Astrobiology community possesses an incredible inventory of planetary analog samples, some incredibly precious, these are scattered across the country in individual freezers with varying degrees of documentation, curation practices, and contamination control. We, as a community, need to change the status quo of how we approach planetary analog research. One of the biggest actions we could take over the next 10 years to change that paradigm would be the creation of a sample repository for Astrobiology relevant materials, providing a centralized, well-curated, wealth of precious samples for the community. Such a collection would create a framework for material and meta-data submission that minimizes burden on the individual PIs, satisfying open data requirements; it would facilitate biosignature research, and aid in the creation of a robust life detection framework; support the development of a standardized sample reference suite for life detection instrumentation; and finally, aid in the development of techniques to be used for future sample return endeavors.

Different research communities are involved in planetary coordinate standardization. Geologists and Remote Sensing specialists work on extending Earth standards to Planets using Geographical Information Systems (GIS) and coordinate descriptions endorsed by the Open Geospatial Consortium (OGC). Astronomers work to define Virtual Observatory (VO) metadata and FITS World Coordinate System (WCS) for planetary bodies. In this proceeding the implementation of the planetary WCS description in Astropy is described. The related new features are available starting from Astropy 6.0. The current work is part of a broader effort involving other consortia (e.g., heliophysics for Solar or magnetospheric reference frames), and focuses on body-fixed frames to support surface and atmosphere studies.

In a series of axisymmetric core-collapse supernova simulations extending up to $\sim 2\,\mathrm{s}$, we identify a regime of pre-collapse central rotation rates ($\sim 1\,\mathrm{Hz}$) that greatly enhances the emission of gravitational waves (GWs) during extended periods of time after bounce. The enhancement is a consequence of the resonance between the frequency of the fundamental quadrupolar $^2f$-mode of oscillation of the proto-neutron star and the frequency of the epicyclic oscillations at the boundary of the inner core. We observe periods of about several hundred milliseconds each where the resonance is active. The GW emission enhancement produces a correlated resonant modulation of the associated neutrino signal at the same frequencies. With GW frequencies of $\mathcal{O}(1\,\mathrm{kHz})$ and strain amplitudes within the sensitivity curves of current and next-generation interferometers at distances of $\mathcal{O}(1\,\mathrm{Mpc})$, this resonant-amplification mechanism may represent a potential game-changer for unveiling the supernova explosion mechanism through multi-messenger astronomy.

Due to the integrated Sachs-Wolfe (ISW) effect, cosmic microwave background (CMB) temperature and polarization fluctuations are correlated with the gravitational lensing potential. Famously, this induces a CMB three-point function, whose shape can be used to constrain dark energy and modifications to gravity. An analogous effect occurs at higher-order, producing an ISW-lensing trispectrum whose amplitude is hitherto unconstrained. We present a detailed discussion of this effect, and define minimum-variance estimators for the ISW-lensing three- and four-point functions. These are implemented within the PolySpec code, and bear strong similarities to the quadratic estimators used in lensing analyses. Applying these tools to Planck, we obtain strong detections of the bispectrum amplitude (consistent with previous works), but find only weak constraints on the trispectrum, due to a strong cancellation between the various ISW-induced contributions. We additionally forecast the constraints from future datasets, finding that (a) simple estimators for the ISW-lensing bispectrum will be severely limited by non-Gaussian modifications to the covariance, and (b) the ISW-lensing trispectrum will be very challenging to detect even with high-resolution future experiments. We finally consider the induced bias on primordial non-Gaussianity amplitudes (and lensing itself), which we show to be large for the bispectrum (as expected) but negligible for the trispectrum.

We present two-dimensional numerical simulations of convection and waves in a 7 solar mass star across stellar ages ranging from zero age to terminal-age-main-sequence. We show that waves efficiently transport angular momentum across the stellar radiative envelope at young ages. However, as the core recedes, leaving behind a "spike" in the buoyancy frequency at the convective-radiative interface, the waves are severely attenuated. This, coupled with the changing stratification throughout the radiation zone, leads to significantly reduced angular momentum transport at later stages on the main sequence. Indeed, the angular momentum transport at mid-main sequence is typically 3-4 orders of magnitude lower than at zero age, though we expect this to be somewhat mitigated by the chemical mixing also induced by such waves. We provide measures of the angular momentum transport, both in terms of the divergence of the Reynolds stress and a typical "wave luminosity". However, we caution that the angular momentum transport drive shear flows, resulting in both slowing and speeding up of radiative interiors. While the values of Reynolds stress and angular momentum transport are only within the context of these limited simulations, they are not significantly different to those found previously using simpler prescriptions, providing some confidence in their applicability.

We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Ly-alpha absorbers (DLAs) at z~4.1-4.5, using the [CII]-158-micron ([CII]) line. We detect seven [CII]-emitting galaxies in the fields of 5 DLAs, all of which have absorption metallicity [M/H] > -1.5. We find that the detectability of these HI-selected galaxies with ALMA is a strong function of DLA metallicity, with a detection rate of 71^{+11}_{-20}% for DLAs with [M/H] > -1.5 and 0^{+18}% for DLAs with [M/H] <-1.5. The identified DLA galaxies have far-infrared properties similar to those of typical star-forming galaxies at z ~ 4, with estimated obscured star-formation rates ranging from ~6 Msun/yr to 110 Msun/yr. High-metallicity DLAs therefore provide an efficient way to identify and study samples of high-redshift, star-forming galaxies without preselecting the galaxies by their emission properties. The agreement between the velocities of the metal absorption lines of the DLA and the [CII] emission line of the DLA galaxy indicates that the metals within the DLA originated in the galaxy. With observed impact parameters between 14 and 59 kpc, this indicates that star-forming galaxies at z ~ 4 have a substantial reservoir of dense, cold neutral gas within their circumgalactic medium that has been enriched with metals from the galaxy.

Recent results regarding dark energy are mutually inconsistent under the $\Lambda$CDM cosmological model, hinting at the possibility of undiscovered physics. However, the currently accepted cosmological parameters come from a joint inference between observational data sets, a process that is formally invalid for inconsistent observations. We will show that many problems can arise when using joint inference on disagreeing observations such as significantly overestimated margins of error, high dependencies on priors, and sensitivities to boundary constraints. Because we do not know if these inconsistencies arise due to errors in observation, poor statistical techniques, or an improper model, it is difficult to fix these problems. We will discuss each scenario in which the analysis method breaks and explore an alternative resampling technique, developing methods that may make determining the sources of tensions in cosmological parameters easier.

We present results of new observations of [OI]145um and [NII]205um emission lines from four star-forming galaxies at redshifts between $z=6.58$ and $7.68$ that have previous detections of \Ciium\ and dust continua. Using ALMA, we successfully detect [OI]145um emission from all targets at $>4\,\sigma$ significance. However, [NII]205um emission is undetected in all galaxies (SNR $<3.5\,\sigma$) except for a tentative detection from A1689-zD1. From the observed high [CII]/[NII] emission line ratios ($\gtrsim20 - 80$), we find that most of the [CII]158um emission arise from neutral gas regions ($3\,\sigma$ lower limits of $\gtrsim 74 - 96\%$). From [OI]145um, [CII]158um lines, and infrared luminosities, we estimate the neutral gas densities of $n_{\rm H}=10^{3.5}$ - $10^6\,{\rm cm^{-3}}$ and the far-ultraviolet (FUV) radiation strengths of $G_0\sim10^{2.5}$-$10^{3}$. While the neutral gas densities are similar to those of high-redshift starburst galaxies, the FUV strengths are lower compared to both local and high-redshift starbursts. Finally, we estimate atomic hydrogen masses using [OI]145um emission lines and the oxygen abundances measured from recent JWST observations. We find gas mass ratios of $f_{\rm gas}\sim0.3$ - $0.8$, which are similar to earlier studies using [CII]158um. Starting from this pilot observation, future large [OI]145um emission line surveys will provide us with currently little-known neutral gas properties of star-forming galaxies in the early Universe.

Element isotopic ratios are powerful tools to reconstruct the journey of planetary material, from the parental molecular cloud to protoplanetary disks, where planets form and accrete their atmosphere. Radial variations in isotopic ratios in protoplanetary disks reveal local pathways which can critically affect the degree of isotope fractionation of planetary material. In this work we present spatially-resolved profiles of the 14N/15N, 12C/13C, and D/H isotopic ratios of the HCN molecule in the PDS 70 disk, which hosts two actively-accreting giant planets. ALMA high spatial resolution observations of HCN, H13CN, HC15N, and DCN reveal radial variations of fractionation profiles. We extract the HCN/HC15N ratio out to ~120 au, which shows a decreasing trend outside the inner cavity wall of the PDS 70 disk located at ~50 au. We suggest that the radial variations observed in the HCN/HC15N ratio are linked to isotope selective photodissociation of N2. We leverage the spectrally resolved hyperfine component of the HCN line to extract the radial profile of the HCN/H13CN ratio between ~40 and 90 au, obtaining a value consistent with the ISM 12C/13C ratio. The deuteration profile is also mostly constant throughout the disk extent, with a DCN/HCN ratio ~0.02, in line with other disk-averaged values and radial profiles in disks around T Tauri stars. The extracted radial profiles of isotopologue ratios show how different fractionation processes dominate at different spatial scales in the planet-hosting disk of PDS 70.

We use the TNG-Cluster simulation to examine how stellar mass and star formation rate (SFR) incompleteness affect the identification of density peaks within galaxy protoclusters at different redshifts. We focus on 352 protoclusters, defined as the set of galaxies that will reside within the virialized region of a $z=0$ cluster halo with total mass $\sim10^{14.3-15.5}~{\rm M}_{\odot}$, and consider only galaxies with ${M}_{\star}> 10^{8.5}~{\rm M}_{\odot}$ (our baseline) at any redshift. We find that ${M}_{\star}$-limited (${M}_{\star} > 10^{9.5}~{\rm M}_{\odot}$) and SFR-limited ($\rm{SFR} > 10~{\rm M}_{\odot} \mathrm{yr}^{-1}$) subpopulations only recover the true highest galaxy density peak in $\lesssim40\%$ of cases within an accuracy of $1.0$ pMpc ($\sim 2-2.5$ arcmin) at $z > 2$. We find that at $z>2$ the highest galaxy density peaks do not generally coincide with the highest dark matter or stellar mass density peaks, and this separation is larger than 0.5 pMpc in $\sim80\%$ of cases. Consequently, the region surrounding the true highest galaxy density peaks are not generally sites of enhanced star formation or accelerated mass growth relative to the remainder of the protocluster. Lastly, we find that the $\sim4$ arcmin apertures typically used to define spectroscopically-confirmed protoclusters are generally much smaller than the $8$ arcmin apertures needed to study the progenitors of the most massive galaxy clusters at $z > 2$.

Theoretical studies on the memory-burden effect suggest that Primordial Black Holes (PBHs) with masses smaller than $10^{15}$ grams may be viable dark matter candidates and, consequently, be potential sources of high-energy particles in the present Universe. In this paper, we investigate the evaporation of memory-burdened PBHs into high-energy gamma-rays. Differently from previous analyses, we account for the attenuation of gamma-rays caused by their interaction with background radiation at energies above $10^5~{\rm GeV}$, as well as the secondary emission from the electromagnetic cascades generated during the propagation through extragalactic space. Performing a likelihood analysis with current gamma-ray data, we place new constraints on the parameter space of memory-burdened PBHs. Our results show that ultra-high-energy diffuse gamma-ray observations set more restrictive bounds than high-energy neutrino data, particularly in scenarios with a strong memory-burden suppression of the PBH evaporation.

We present the first results from MARTA (Measuring Abundances at high Redshift with the T$_e$ Approach), a programme leveraging ultra-deep, medium-resolution JWST/NIRSpec spectroscopy to probe the interstellar medium (ISM) of star-forming galaxies at $z \sim 2 - 3$. We report detections of one or more auroral lines, including [O III]$\lambda4363$, [O II]$\lambda\lambda7320,7330$, [S II] $\lambda4068$, and [S III] $\lambda6312$ for 16 galaxies in the sample, providing measurements of multiple ionic temperatures. We tested the validity of the T[O II]-T[O III] relation at high redshift considering a total sample of 21 objects including literature data, and obtained a shallower slope than in the low-$z$ literature. However, such a slope is consistent with low-redshift data when ultra-low metallicity objects are considered. We assessed the correlation of the T[O II]-T[O III] relationship and its scatter on different physical parameters, finding a mild correlation with the ionisation parameter and radiation field hardness, while no significant correlation with gas density. The location of high-redshift data is also consistent with the low-$z$ literature in the T[O II]-T[S II], and T[S III]-T[O III] relations, although this conclusion is limited with low-number statistics. Finally, we leveraged our sample together with a comprehensive compilation of galaxies with [O III]$\lambda4363$ detections from the literature to recalibrate classical strong-line diagnostics at high redshift. MARTA represents a key addition in this space because it provides direct metallicities at moderately high oxygen abundances (12+log(O/H) $\sim8.0-8.4$).

Recent eROSITA measurements of the radial profiles of the hot CGM in the Milky-Way stellar mass (MW-mass) regime provide us with a new benchmark to constrain the hot gas around MW-mass central and satellite galaxies and their halo mass distributions. Modelling this rich data set with state-of-the-art hydrodynamical simulations is required to further our understanding of the shortcomings in the current paradigm of galaxy formation and evolution models. We develop forward models for the stacked X-ray radial surface brightness profile measured by eROSITA around MW-mass galaxies. Our model contains two emitting components: hot gas (around central galaxies and satellite galaxies hosted by more massive halos) and X-ray point sources (X-ray binaries and Active Galactic Nuclei). We model the hot gas profile using the TNG300-based products. We generate mock observations with our TNG300-based model (matching stellar mass and redshift with observations) with different underlying halo mass distributions. We show that for the same mean stellar mass, a factor 2x increase in the mean value of the underlying halo mass distribution results in a ~4x increase in the stacked X-ray luminosity from the hot CGM. The point sources are described by a simple point-spread-function (PSF) of eROSITA, and we fit their normalization in this work. Using empirical models to derive a permissible range of AGN and XRB luminosities in the MW-mass X-ray galaxy stack, we choose our forward model best describing the hot CGM for the eROSITA observations. We find that at < 40 kpc from the galaxy centre, the hot CGM from central galaxies and the X-ray point sources emission each account for 40-50% of the total X-ray emission budget. In summary, we show that the gas physics driving the shape of the observed hot CGM (in stellar-mass-selected samples) is tightly correlated by the underlying halo-mass distribution (abridged).

Mapping the Milky Way spiral arms in the vertical direction remains a challenging task that has received little attention. Taking advantage of recent results that link the position of the Galactic spiral arms to metal-rich regions in the disc, we analyse a sample of young giant stars from {\it Gaia} DR3 and use their metallicity distribution to produce a 3D metallicity excess map. The map shows signatures of the spiral arms, whose vertical height vary across the Galactic disc, reaching up to 400 pc in amplitude and exhibiting vertical asymmetries with respect to the midplane. Specifically, the Perseus arm displays a high vertical asymmetry consistent with the Galactic warp. Moreover, we find evidence of a metal-rich stellar structure that oscillates vertically, nearly in phase with the arrangement of star-forming regions named the Radcliffe Wave. This new structure is larger and extends beyond the Radcliffe Wave, reaching vertical amplitudes of $\sim$ 270 pc and extending for at least 4 kpc in length. We confirm that for at least half of its length this Extended Radcliffe Wave is the inner edge of the Local Arm. The finding of a metal-rich stellar counterpart of the Radcliffe Wave shows that mapping the three-dimensional metallicity distribution of young stellar populations reveals key information about the structures and chemical enrichment in the Galactic disc.

The UV radiation from high redshift quasars causes a local deficit in the neutral hydrogen absorption (Lyman-alpha forest) in their spectra, known as the proximity effect. Measurements from small samples of tens to hundreds of quasars have been used to constrain the global intensity of the UV background radiation, but so far the power of large-scale surveys such as the Sloan Digital Sky Survey and the Dark Energy Spectroscopic Instrument (DESI) survey has not been used to investigate the UV background in more detail. We develop a CDM-based halo model of the quasar proximity effect, which accounts by construction for the fact that quasars reside in overdense regions. We test this model on quasar Lyman-alpha spectra from the ASTRID cosmological hydrodynamic simulation, which includes self-consistent formation of quasar black holes and the intergalactic medium surrounding them. Fitting the model to individual quasar spectra, we constrain two parameters, r_eq (the radius at which the local quasar radiation intensity equals the background), and the quasar bias b_q (related to host halo mass). We find that r_eq can be recovered in an unbiased fashion with a statistical uncertainty of 25-50% from a single quasar spectrum. Applying such fitting to samples of millions of spectra from e.g., DESI would allow measurement of the UVBG intensity and its evolution with redshift with high precision. We use another, larger-scale, lower resolution simulation (Uchuu) to test how such a large sample of proximity effect measurements could be used to probe the spatial fluctuations in the intergalactic radiation field. We find that the large-scale structure of the UV radiation intensity could be mapped and its power spectrum measured on 100-1000 Mpc/h scales. This could allow the large-scale radiation field to join the density field as a dataset for constraining cosmology and the sources of radiation.

We are experiencing a golden age of experimental cosmology, with exact and accurate observations being used to constrain various gravitational theories like never before. Alongside these advancements, energy conditions play a crucial theoretical role in evaluating and refining new proposals in gravitational physics. We investigate the energy conditions (WEC, NEC, DEC, and SEC) for two $f(Q, L_m)$ gravity models using the FLRW metric in a flat geometry. Model 1, $f(Q, L_m) = -\alpha Q + 2L_m + \beta$, features linear parameter dependence, satisfying most energy conditions while selectively violating the SEC to explain cosmic acceleration. The EoS parameter transitions between quintessence, a cosmological constant, and phantom energy, depending on $\alpha$ and $\beta$. Model 2, $f(Q, L_m) = -\alpha Q + \lambda (2L_m)^2 + \beta$, introduces nonlinearities, ensuring stronger SEC violations and capturing complex dynamics like dark energy transitions. While Model 1 excels in simplicity, Model 2's robustness makes it ideal for accelerated expansion scenarios, highlighting the potential of $f(Q, L_m)$ gravity in explaining cosmic phenomena.

this http URL present a comprehensive photometric and spectroscopic study of the nearby Type II supernova (SN) 2023ixf, with our extensive observations spanning the phases from ~3 to over 600 days after the first light.\\ this http URL aim of this study is to obtain key information on the explosion properties of SN\,2023ixf and the nature of its progenitor.\\ this http URL observational properties of SN\,2023ixf are compared with those of a sample of Type IIP/L SNe to investigate commonalities and diversities. We conduct a detailed analysis of temporal evolution of major spectral features observed throughout different phases of the SN\,2023ixf explosion. Several interpretations are addressed through a comparison between the data and the model spectra for progenitor stars within a range of zero-age main sequence (ZAMS) masses.\\ this http URL observations indicate that SN\,2023ixf is a transitional SN that bridges the gap between Type IIP and IIL subclasses of H-rich SNe, characterized by a relatively short plateau ($\lesssim 70$\,d) in the light curve. It shows a rather prompt spectroscopic evolution toward the nebular phase; emission lines of Na, O, H, and Ca in nebular spectra all exhibit multipeak profiles, which might be attributed to bipolar distribution of the ejecta. In particular, the H$\alpha$ profile can be separated into two central peaked components (with a velocity of about 1500\,km\,s$^{-1}$) that is likely due to nickel-powered ejecta and two outer peak/box components (with a velocity extending up to ~8000 km\,s$^{-1}$) that can arise from interaction of the outermost ejecta with a circumstellar shell at a distance of $\sim6.2\times10^{15}$cm. The nebular-phase spectra of SN\,2023ixf show good agreement with those predicted by model spectra for progenitor stars with a ZAMS mass ranging from 15 to 19\,M${_\odot}$. A distance $D = 6.35^{+0.31}_{-0.39}$\,Mpc is estimated for M101.

We present a methodology for extracting firn ice properties using S-parameter reflection coefficients (`$S_{11}$') of antennas lowered into boreholes. Coupled with Finite-Difference Time Domain (FDTD) simulations and calculations, a depth-dependent $S_{11}$ profile can be translated into a refractive index profile. Since the response of an antenna deployed into a dry borehole depends on the diameter of the hole, multi-year $S_{11}$ measurements also permit an estimate of borehole closure complementary to estimates based on calipers or other dedicated mechanical loggers. We present first results, based on data taken in August, 2024 from boreholes at Summit Station, Greenland. We estimate borehole closure resolution of $\mathbf{\sim 2}$mm and also derive an index of refraction profile consistent with previous measurements.

The ejecta from binary neutron star mergers, which powers its associated kilonova, can inform us about source properties, merger dynamics, and the dense nuclear matter equation of state. While now in the era of multi-messenger astronomy, we remain more likely to observe purely electromagnetic (or purely gravitational-wave) signals due to the duty cycle and maximum observing distance of gravitational wave detectors. It is thus imperative to be able to perform high-accuracy parameter inference of purely electromagnetic detections. Here, we use a collection of ejecta formulae in an end-to-end analysis to generate mock multi-wavelength kilonova signals and recover the intrinsic merger parameters. By generating mock light curves for a broad range of possible mergers and with a variety of ejecta models, and then performing parameter estimation with different ejecta models, we measure how reliably and consistently we can use the 'map' between intrinsic and outflow properties provided by the formulae to gain source (intrinsic) information from purely electromagnetic detections (observables). We find that the posteriors probability densities are prone to biases when we vary the choice of reference model for our sampler, especially away from the best studied region of the binary parameter space, i.e. near equal mass, low mass binaries. This highlights both the need for improved models for the mass of the ejecta, and the need to exert caution when performing parameter estimation with a single mass model. We also find that most models predict that parameter degeneracies in kilonova light curves are largely orthogonal to those measurement observables, such as the chirp mass, from gravitational wave signals, indicating that kilonovae may provide a lot of additional information even in multi-messenger observations, if better modeled.

We present a novel analysis of observational systematics through the emission line stacking of the MeerKLASS L-band deep-field intensity maps, following the detection reported in arXiv:2407.21626. A stacking signal is obtained by stacking the 21cm intensity map cubelets around the galaxy positions from the GAMA survey at $0.39\lesssim z \lesssim 0.46$. An extensive simulation framework is built to study the viability of the stacking detection, the covariance estimation, and the model inference, which are then applied to the data. The statistical significance of the detection is $8.66\sigma$ when averaged into an angular map, and $7.45\sigma$ when averaged into a spectrum. The stacked spectrum exhibits an oscillating component of systematics, and we provide evidence that the systematics is a convolutional effect on the map data. The frequency of the oscillation matches the diffraction from the secondary reflector into the primary beam of the MeerKAT telescope. Bayesian inference can be used to constrain the systematics and the average HI emission of the galaxies. The fitting of the parameters gives a constraint on the systematics frequency $\nu_{\rm sys}\,[{\rm MHz}] = 17.90^{+6.53}_{-4.27}$. The amplitude of the systematics is $>6.71\%$ at the 95\% confidence level. A tentative measurement of the average HI mass of the sources is achieved at ${\rm log}_{10}[\langle M_{\rm HI}\rangle/M_\odot ]=9.84^{+0.48}_{-0.59}$, limited by the narrow redshift bin of the data, the existence of the systematics, and the low-density galaxy sample. These shortfalls will be resolved for future MeerKLASS data to enable accurate measurements of the HI density through stacking of 21cm intensity maps.

3D Magnetohydrodynamic (MHD) resistive simulations have highlighted the significance of ubiquitous turbulence to drive fast reconnection. It has been demonstrated that particle acceleration via reconnection in 3D magnetized flows, where turbulence is embedded in large-scale magnetic fields such as in relativistic jets and accretion flows around compact sources, is remarkably efficient. Particles experience Fermi acceleration across all scales of turbulent reconnection layers, outweighing the considerably slower drift acceleration mechanism. This stands in contrast to recent assertions stemming from PIC simulations, that claimed the dominance of the latter process. In this talk, I review how particle acceleration is driven by 3D turbulent reconnection to very high energies and demonstrate its potential in magnetized regions of AGN jets and accretion disks to explain the gamma-ray and neutrino emissions. Applications to sources such as TXS 0506+056, MRK 501, and NGC 1068 are discussed.

We present the construction of the ground state of the Gross-Pitaevskii-Poisson equations using genetic algorithms. By employing numerical solutions, we develop an empirical formula for the density that works within the considered parameter space. Through the analysis of both numerical and empirical solutions, we investigate the stability of these ground state solutions. Our findings reveal that while the numerical solution outperforms the empirical formula, both solutions lead to similar oscillation modes. We observe that the stability of the solutions depends on specific values of the central density and the nonlinear self-interaction term, and establish an empirical criterion delineating the conditions under which the solutions exhibit stability or instability.

We present the multiwavelength spectral energy distributions (SEDs) for 65 luminous broad absorption line (BAL) quasars with redshifts $1.55 \lesssim z \lesssim 3.50$ from the Gemini Near Infrared Spectrograph - Distant Quasar Survey (GNIRS-DQS). We integrate data from a variety of ground- and space-based observatories to construct a comprehensive spectral profile of these objects from radio through X-rays. In addition, we present a mid-infrared to X-ray composite SED of these sources. Our dataset represents the most uniform sample of BAL quasars, providing a statistically robust set of SEDs. Our findings indicate that the BAL quasars in the GNIRS-DQS sample exhibit significant reddening in the ultraviolet-optical continuum relative to their non-BAL counterparts, consistent with previous studies. Notably, our analysis reveals no significant differences in the mid- or near-infrared spectral regime between BAL and non-BAL quasars. In line with previous work, we find no strong evidence that BAL and non-BAL quasars possess fundamentally different SEDs, also consistent with recent findings that both groups display similar rest-frame optical emission-line properties.

We carried out the first high-resolution transit observations of the exoplanet WASP-49 Ab with Keck/HIRES. Upon custom wavelength calibration we achieve a Doppler RV precision of $<$ 60 {\mbox{${\rm m\,s}^{-1}$}}. This is an improvement in RV stability of roughly 240 {\mbox{${\rm m\,s}^{-1}$}} with respect to the instrument standard. We report an average sodium flux residual of $\Delta \mathcal{F}_{NaD}/ \mathcal{F}_{\star} (\lambda) \sim$ 3.2 $\pm$ 0.4 $\%$ (8.0 $\sigma$) comparable to previous studies. Interestingly, an average Doppler shift of -6.2 $\pm$ 0.5 {\mbox{${\rm km\,s}^{-1}$}} (12.4 $\sigma$) is identified offset from the exoplanet rest frame. The velocity residuals \textit{in time} trace a blueshift (v$_{\Gamma, ingress} \sim$ -10.3 $\pm$ 1.9 {\mbox{${\rm km\,s}^{-1}$}}) to redshift (v$_{\Gamma, egress} \sim$ +4.1 $\pm$ 1.5 {\mbox{${\rm km\,s}^{-1}$}}) suggesting the origin of the observed sodium is unlikely from the atmosphere of the planet. The average Na light curves indicate a depth of $\Delta \mathcal{F}_{NaD} /\mathcal{F}_{\star} (t) \sim$ 0.47 $\pm$ 0.04 \% (11.7 $\sigma$) enduring $\lesssim$ 90 minutes with a half-max duration of $\sim$ 40.1 minutes. Frequent high-resolution spectroscopic observations will be able to characterize the periodicity of the observed Doppler shifts. Considering the origin of the transient sodium gas is of unknown geometry, a co-orbiting natural satellite may be a likely source.

We propose the use of the James Webb Space Telescope (JWST) in simultaneous observations with an Earth-based telescope for parallax measurements to tightly constrain the orbital trajectory of hazardous near-Earth objects (NEOs). We demonstrate the significant reduction in localization error with varying epochs of observation at the potential time-of-impact via a Monte Carlo simulated case study of 2024 YR4, an Apollo-type near-Earth asteroid. By leveraging the L2-Earth baseline and the considerable parallax angles formed, we highlight the unexplored potential for improved localization of NEOs through parallax observations with JWST.

Accurate modeling of the inflationary gravitational waves (GWs) requires time-consuming, iterative numerical integrations of differential equations to take into account their backreaction on the expansion history. To improve computational efficiency while preserving accuracy, we present SageNet (Stiff-Amplified Gravitational-wave Emulator Network), a deep learning framework designed to replace conventional numerical solvers. SageNet employs a Long Short-Term Memory architecture to emulate the present-day energy density spectrum of the inflationary GWs with possible stiff amplification, $\Omega_\mathrm{GW}(f)$. Trained on a data set of 25,689 numerically generated solutions, SageNet allows accurate reconstructions of $\Omega_\mathrm{GW}(f)$ and generalizes well to a wide range of cosmological parameters; 89.3% of the test emulations with randomly distributed parameters exhibit errors of under 4%. In addition, SageNet demonstrates its ability to learn and reproduce the artificial, adaptive sampling patterns in numerical calculations, which implement denser sampling of frequencies around changes of spectral indices in $\Omega_\mathrm{GW}(f)$. The dual capability of learning both physical and artificial features of the numerical GW spectra establishes SageNet as a robust alternative to exact numerical methods. Finally, our benchmark tests show that SageNet reduces the computation time from tens of seconds to milliseconds, achieving a speed-up of ~$10^4$ times over standard CPU-based numerical solvers with the potential for further acceleration on GPU hardware. These capabilities make SageNet a powerful tool for accelerating Bayesian inference procedures for extended cosmological models. In a broad sense, the SageNet framework offers a fast, accurate, and generalizable solution to modeling cosmological observables whose theoretical predictions demand costly differential equation solvers.

Gas giant planets, if present, are the most massive objects in a planetary system and play a pivotal role in shaping its overall architecture. The formation of these planets has constantly been a central issue in planetary science. Increasing evidence from spacecraft explorations of Jupiter and Saturn, as well as telescope observations of exoplanets, has provided new constraints on the formation process of gas giant planets. The classic challenge of explaining formation timescales still remains a significant issue, while new constraints on planetary interiors have introduced additional complexities. Recent shifts away from the single-size planetesimal hypothesis, nevertheless, show promise in resolving these problems. Additionally, various discoveries regarding exoplanets have led to theoretical improvements, while the discovery of numerous super-Earths and sub-Neptunes has posed new challenges in understanding gas accretion. This review synthesizes the latest theoretical advancements, discussing resolved issues and emerging challenges in giant planet formation.

In this study, we present constraints on the parameters of three well-known $f(R)$ gravity models, viz. (i) Hu-Sawicki, (ii) Starobinsky, and (iii) ArcTanh by using a joint analysis of recent cosmological observations. We drive the analytical approximations for the Hubble parameter, $H(z)$, and cosmological distances in terms of the Hubble constant $(H_0)$, matter density $(\Omega_{m0})$, and a deviation parameter $b$ for each model. Our analysis uses data from four cosmological observations: (a) Hubble parameter measurements (Cosmic Chronometers), (b) Type Ia Supernovae (Union 3.0), (c) Baryon Acoustic Oscillations (DESI-2024), and (d) Gamma-Ray Bursts (GRBs). We first optimize the models using each dataset independently, and subsequently, we perform a comprehensive joint analysis combining all four datasets. Our results show that the Hu-Sawicki and ArcTanh models do not deviate significantly from the $\Lambda$CDM model at 68% confidence level for individual datasets and remain consistent at 99% confidence level in the joint analysis. In contrast, the Starobinsky model shows a strong deviation and appears as a viable alternative to $\Lambda$CDM. We also constrain the transition redshift parameter, i.e., $z_t$, and the obtained value agrees with values inferred from both early-time measurement (Planck) and late-time data from Type Ia Supernovae. These results support the potential of $f(R)$ gravity to explain the late-time cosmic acceleration effectively.

The Coma cluster, embedded in a cosmic filament, is a complex and dynamically active structure in the local Universe. Applying a density-based member selection (dbscan) to data from the Sloan Digital Sky Survey (SDSS), we identify its virilised core and zero-velocity boundary. Cross-correlating with the Cosmicflows-4 (CF4) catalogue enables a velocity-distance analysis, incorporating radial infall models and redshift-independent distance estimators. This reveals, for the first time, the Hubble flow surrounding Coma, a first step to investigate the entanglement between the dark matter in bound objects and the dark energy driving the expansion of their surroundings. The distance to the Coma centre is determined as $69.959 \pm 0.012 \, h^{-1}~\text{Mpc}$. From dbscan, we infer a virial radius of $r_{\rm vir} = \left(1.95 \pm 0.12\right)\,h^{-1}~\text{Mpc}$ and a turnaround of $r_{\rm ta} \geq 4.87~{h}^{-1}~\mbox{Mpc}$. Combining the SDSS redshifts with the CF4 distances, we estimate the Hubble constant to be $H_0 = (73.10 \pm 0.92)~\mbox{km}/\mbox{s}/\mbox{Mpc}$. However, with different calibrations for the distance moduli, $H_0$ varies between $[72, 80]$ km/s/Mpc. Mass estimates via caustics, the virial theorem, and the Hubble-flow method yield $M = [0.77, 2.0] \times 10^{15}\,h^{-1}\,M_{\odot}$, consistent with prior studies. Our systematic approach maps the structure of Coma into the local Hubble flow and shows the degeneracies between dynamical parameters such as the Hubble constant, the virial radius, and the total mass.

The ability to accurately determine the rotation rate and spin axis of active satellites during deployment, during phases of uncertain operations (e.g. loss of control, potential fuel leaks) and particularly for defunct satellites to assess suitability of removal of space objects by active debris removal is increasingly important. Conventional techniques, such as optical photometry, face challenges in providing precise attitude information. In this work, we propose a tri-static ground-based satellite laser ranging (SLR) approach combined with three onboard laser retroreflectors for precise satellite attitude determination. Via this approach our method achieves true 3D triangulation of the reflectors' positions in space, enabling a highly accurate estimation of the satellite's attitude. This multi-station configuration overcomes limitations of existing single-station SLR techniques that rely on indirect inference, e.g. Fourier analysis of range residuals, or lead to multiple possible attitude solutions. We demonstrate through simulations that our approach can estimate the spin rate and axis of a satellite with high precision, on the order of 0.1 deg/sec and 1 deg, respectively. Notably, this can be done with data from only a single pass and does not require observation of a whole satellite rotation period. We show how the layout of retroreflectors are paramount to the effectiveness of the method. We provide placement strategies to maximize attitude determination performance to allow operators to incorporate retroreflectors effectively into their own satellites. These contributions lay the groundwork for a complete ground-based solution for attitude determination, significantly improving current methods and directly supporting ADR efforts.

There is a growing interest in searching for coronal mass ejections (CMEs) in other stellar systems because they are thought to be one of the important factors shaping planetary atmospheres. We investigated the possible spectral signatures related to stellar CMEs using magnetohydrodynamic simulations and spectral synthesis techniques. Blue wing enhancements of the synthetic coronal line profiles caused by the line-of-sight motion of plasma were observed during the simulated CME events. We included instrumental conditions in the spectral synthesis and tested the detectability of the asymmetries under different instrumental broadening conditions. The results show that blue wing asymmetries are visible in some EUV lines with spectral resolutions higher than around 2000, and the line-of-sight velocities of CMEs obtained from asymmetry analysis techniques are comparable to the CME velocities derived from three-dimensional model outputs. However, when the spectral resolution drops below 2000, the asymmetries in the blue wings become barely visible, but blue shifts in the line centroids with velocities around -100 to -200 km/s are observed. We suggest a method of using MHD simulation to synthesize line profiles and analyze their asymmetries which may help to guide future instrument design in terms of detecting stellar CMEs through Doppler shifts or asymmetries of coronal spectral lines.

We describe physical processes affecting the formation, trapping, and outgassing of molecular oxygen (O2) at Europa and Ganymede. Following Voyager measurements of their ambient plasmas, laboratory data indicated that the observed ions were supplied by and would in turn impact and sputtering their surfaces, decomposing the ice and producing thin O2 atmospheres. More than a decade later, Europa's ambient O2 was inferred from observations of the O aurora and condensed O2 bands at 5773 and 6275 angstroms were observed in Ganymede's icy surface. More than another decade later, the O2 atmosphere was shown to have a dusk/dawn enhancement, confirmed by Juno data. Although the incident plasma produces these observables, processes within the surface are still not well understood. Here we note that incident plasma produces a non-equilibrium defect density in the surface grains. Subsequent diffusion leads to the formation of voids and molecular products, some of which are volatile. Although some volatiles are released into their atmospheres, others are trapped at defects or in voids forming gas bubbles, which might be delivered to their subsurface oceans. Here we discuss how trapping competes with annealing of the radiation damage. We describe differences observed at Europa and Ganymede and roughly determine the trend with latitude of O2 bands on Ganymede's trailing hemisphere. This understanding is used to discuss the importance of condensed and adsorbed O2 as atmospheric sources, accounting for dusk/dawn enhancements and temporal variability reported in condensed O2 band depths. Since plasma and thermal annealing timescales affect the observed O2 variability on all of the icy moons, understanding the critical physical processes of O2 can help determine the evolution of other detected oxidants often suggested to be related to geological activity and venting.

The recent detection of nanohertz stochastic gravitational-wave backgrounds (SGWBs) by pulsar timing arrays (PTAs) promises unique insights into astrophysical and cosmological origins. However, traditional Markov Chain Monte Carlo (MCMC) approaches become prohibitively expensive for large datasets. We employ a normalizing flow (NF)-based machine learning framework to accelerate Bayesian inference in PTA analyses. For the first time, we perform Bayesian model comparison across SGWB source models in the framework of machine learning by training NF architectures on the PTA dataset (NANOGrav 15-year) and enabling direct evidence estimation via learned harmonic mean estimators. Our examples include 10 conventional SGWB source models such as supermassive black hole binaries, power-law spectrum, cosmic strings, domain walls, scalar-induced GWs, first-order phase transitions, and dual scenario/inflationary gravitational wave. Our approach jointly infers 20 red noise parameters and 2 SGWB parameters per model in $\sim 20$\,hours (including training), compared to $\sim 10$\,days with MCMC. Critically, the NF method preserves rigorous model selection accuracy, with small Hellinger distances ($\lesssim 0.3$) relative to MCMC posteriors, and reproduces MCMC-based Bayes factors across all tested scenarios. This scalable technique for SGWB source comparison will be essential for future PTA expansions and next-generation arrays such as the SKA, offering orders-of-magnitude efficiency gains without sacrificing physical interpretability.

The new Dark Energy Spectroscopic Instrument (DESI) DR2 results have strengthened the possibility that dark energy is dynamical, i.e., it has evolved over the history of the Universe. One simple, but theoretically well motivated and widely studied, physical model of dynamical dark energy is minimally coupled, single-field quintessence $\phi$ with an exponential potential $V(\phi)=V_0\,e^{-\lambda\phi}$. We perform a full Bayesian statistical analysis of the model using the DESI DR2 data, in combination with other cosmological observations, to constrain the model's parameters and compare its goodness of fit to that of the standard $\Lambda$CDM model. We find that the quintessence model provides a significantly better fit to the data, both when the spatial curvature of the Universe is fixed to zero and when it is allowed to vary. The significance of the preference varies between $\sim3.3\sigma$ and $\sim3.8\sigma$, depending on whether the curvature density parameter $\Omega_K$ is fixed or varied. We obtain the values $0.698^{+0.173}_{-0.202}$ and $0.722^{+0.182}_{-0.208}$ at the $68.3\%$ (i.e., $1\sigma$) confidence level for the parameter $\lambda$ in the absence and the presence of $\Omega_K$, respectively, which imply $\sim3.5\sigma$ preference for a nonzero $\lambda$. We also obtain $\Omega_K=0.003\pm 0.001$, which implies $\sim3\sigma$ preference for a positive $\Omega_K$, i.e., a negative curvature. Finally, we discuss the differences between quintessence and phenomenological parametrizations of the dark energy equation-of-state parameter, in particular the Chevallier-Polarski-Linder (CPL) parametrization.

A wide variety of scenarios for the origin of life have been proposed, with many influencing the prevalence and distribution of biosignatures across exoplanet populations. This relationship suggests these scenarios can be tested by predicting biosignature distributions and comparing them with empirical data. Here, we demonstrate this approach by focusing on the cyanosulfidic origins-of-life scenario and investigating the hypothesis that a minimum near-ultraviolet (NUV) flux is necessary for abiogenesis. Using Bayesian modeling and the \bioverse\ survey simulator, we constrain the probability of obtaining strong evidence for or against this ``UV Threshold Hypothesis'' with future biosignature surveys. Our results indicate that a correlation between past NUV flux and current biosignature occurrence is testable for sample sizes of $\gtrsim$50 planets. The diagnostic power of such tests is critically sensitive to the intrinsic abiogenesis rate and host star properties, particularly maximum past NUV fluxes. Surveys targeting a wide range of fluxes, and planets orbiting M dwarfs enhance the chances of conclusive results, with sample sizes $\gtrsim$100 providing $\gtrsim$80\% likelihood of strong evidence if abiogenesis rates are high and the required NUV fluxes are moderate. For required fluxes exceeding a few hundred erg/s/cm$^2$, both the fraction of inhabited planets and the diagnostic power sharply decrease. Our findings demonstrate the potential of exoplanet surveys to test origins-of-life hypotheses. Beyond specific scenarios, this work underscores the broader value of realistic survey simulations for future observatories (e.g., HWO, LIFE, ELTs, Nautilus) in identifying testable science questions, optimizing mission strategies, and advancing theoretical and experimental studies of abiogenesis.

Using Keck DEIMOS spectra of stars in the Andromeda (M31) and Triangulum (M33) galaxies, selected from the large multi-band (near ultraviolet, visible light, and near infrared) Hubble Space Telescope surveys PHAT and PHATTER, respectively, we have identified a subset of stars that contain a previously unnoticed weak spectral absorption feature around 8000 Angstrom (0.8 micron). This absorption feature appears to be associated with the cyanogen (CN) molecule. Strong CN spectral absorption is a standard feature of carbon stars, which are thought to be intermediate mass (2-3 ~ M_sun) stars with C/O > 1 in the thermally-pulsating asymptotic giant branch phase of stellar evolution. However, the stars that are the focus of this paper are characterized by a weak version of this CN spectral absorption feature in a spectrum that is otherwise dominated by normal O-rich spectral absorption lines such as TiO and/or the Ca near infrared triplet. We have dubbed these stars "weak CN" stars. We present an automated method for identifying weak CN stars in M31 and M33, and examine their photometric properties in relation to model isochrones and stellar tracks. We find that weak CN stars tend to be fairly localized in color-magnitude space, and appear to be red supergiant stars with masses ranging from 5-10 M_sun, overall lifetimes of about 40-50 Myr, and currently in the core He burning phase of stellar evolution.

An uncatalogued bright X-ray transient was detected with MAXI on November 9, 2024, named MAXI J1752$-$457. The NinjaSat X-ray observatory promptly observed the source from November 10 to 18 under the severe Sun angle constraint, which hampered other X-ray observatories from performing follow-up monitoring. The MAXI and NinjaSat light curves in the 2-10 keV band showed fast and slow decaying components at the early and late phases, approximated by exponential functions with e-folding constants of 1.2 $\pm$ 0.2 and 14.9 $\pm$ 0.9 hours (1$\sigma$ errors), respectively. A single blackbody model reproduces the X-ray spectrum with a softening trend of its temperature decreasing from 1.8 $\pm$ 0.1 keV to 0.59 $\pm$ 0.06 keV. Assuming the unknown source distance at 8 kpc, at which the initial X-ray luminosity roughly corresponds to the Eddington limit, the shrinking blackbody radius was estimated at 5-11 km. This X-ray brightening is interpreted as a superburst in a Galactic low-mass X-ray binary, which is powered by thermonuclear burning triggered presumably by carbon ignition at a thick layer in the neutron-star outer/deep crust. The transition between two decaying components occurred at 5.5-7.7 hours, corresponding to the thermal time scale of the burning layer. The ignition column density is estimated to be $\sim$(2.8-5.1)$\times 10^{12}$ g cm$^{-2}$.

The peaked-spectrum (PS) sources exhibit turnover characteristics in their broad radio spectra. However, the mechanism underlying this phenomenon remains elusive. The two most common hypotheses are synchrotron self-absorption (SSA) and free-free absorption (FFA). By incorporating multiple absorption scenarios, we propose a multi-mechanism hybrid (MMH) model, which aligns well with current observational data and provides a good physical explanation. Using the GLEAM survey data, we identified a sample of 4,315 sources with peak frequencies approximately between 72--3000 MHz, most of which are MHz-peaked-spectrum sources (MPS). Our analysis shows that instead of SSA, the FFA is the dominant mechanism in producing the spectral turnover for most of the sources in this sample. The index of the optically thick spectrum alpha_thick has a lower boundary due to the FFA, and the steeper alpha_thick indicates a complex multi-absorption mechanism. In particular, the external FFA produces substantial alpha_thick, which exhibits a weak correlation with the peak frequency. Future ultra-long wavelength observations would also provide data on the spectrum of these sources at even lower frequencies. Determining the absorption mechanism that shaped the spectrum of these sources would be a crucial part of understanding their nature.

this http URL is the first paper of a series aiming to determine the fractions and birth rates of various types of supernovae (SNe) in the local Universe. Aims. In this paper, we aim to construct a complete sample of SNe in the nearby universe and provide more precise measurement of subtype fractions. this http URL carefully selected our SN sample at a distance of < 40 Mpc mainly from wide-field surveys conducted over the years from 2016 to 2023. this http URL sample contains a total of 211 SNe, including 109 SNe II, 69 SNe Ia, and 33 SNe Ibc. With the aid of sufficient spectra, we can obtain relatively accurate subtype classifications for all SNe in this sample. After corrections for the Malmquist bias, this volume-limited sample gives fractions of SNe Ia, SNe Ibc, and SNe II as $30.4^{+3.7}_{-11.5}\%$, $16.3^{+3.7}_{-7.4}\%$, and $53.3^{+9.5}_{-18.7}\%$, this http URL the SN Ia sample, the fraction of the 91T-like subtype becomes relatively low (~5.4\%), while that of the 02cx-like subtype shows a moderate increase (~6.8\%). In the SN Ibc sample, we find significant fractions of broadlined SNe Ic (~18.0\%) and SNe Ibn (~8.8\%). The fraction of 87A-like subtype is determined as ~2.3\% for the first time, indicating rare explosions from blue supergiant stars. We find that SNe Ia show a double peak number distribution in S0- and Sc-type host galaxies, which may serve as a straightforward evidence for the presence of "prompt" and "delayed" progenitor components giving rise to SN Ia explosions. Several subtypes of SNe such as 02cx-like SNe Ia, broadlined SNe Ic, SNe IIn (and perhaps SNe Ibn) are found to occur preferentially in less massive spiral galaxies, favoring their associations with young stellar progenitors. Moreover, the 02cx-like subtype shows a trend of exploding in the outer skirt of their hosts, suggestive of metal-poor progenitors.

DESI has reported a dynamical dark energy (DE) signal based on the $w_0 w_a$CDM model that is in conflict with Hubble tension. Recalling that the combination of DESI DR1 BAO and DR1 full-shape (FS) modeling are consistent with $\Lambda$CDM, in this letter we comment on the status of fluctuations in DR1 BAO documented in \cite{DESI:2024mwx, Colgain:2024xqj} in the DR2 update. In particular, we note that neither DR1 BAO nor DR2 BAO nor DR2 BAO+CMB confronted to the $w_0 w_a$CDM model with relaxed model parameter priors confirm late-time accelerated expansion today. Translating DESI BAO constraints into flat $\Lambda$CDM constraints, we observe that the DESI LRG1 constraint remains the most prominent outlier preferring larger $\Omega_m$ values, LRG2 switches from smaller to larger $\Omega_m$ values relative to Planck-$\Lambda$CDM, and ELG data drive the relatively low $\Omega_m$ in the full DR2 BAO. We observe that one cannot restore $w_0 = -1$ within one $1 \sigma$ by removing either LRG1 or LRG2, but LRG2 in DR2, in contrast to LRG1 in DR1, now has a greater bearing on $w_0 > -1$. We conclude that the BAO has yet to stabilise, but the general trend is towards greater consistency with DESI DR1 FS modeling results, where there may be no dynamical DE signal in DESI data alone.

Recent observations of the accretion disk around the Herbig Ae/Be star HD169142 revealed its complex and asymmetric morphology indicating the presence of planets. The knowledge of the magnetic field structure in host stars is indispensable for our understanding of the magnetospheric interaction between the central stars, the circumstellar (CS) environment, and planetary companions. We intend to study the geometry of the magnetic field of HD169142. We measured the mean longitudinal magnetic field from high resolution ESPaDOnS and HARPSpol spectra of HD169142 using the Least Square Deconvolution technique. Additionally, the spectral variability of hydrogen lines is studied using dynamical spectra. Our analysis of the Stokes V spectra reveals the presence of definitely detected narrow Zeeman features observed using line masks with neutral iron lines. On two observing epochs, we also obtain marginally detected broad Zeeman features. To explain the simultaneous appearance of narrow and broad Zeeman features, we discuss different scenarios, including one scenario related to a non-photospheric origin of the narrow Zeeman features due to magnetospheric interaction with warm CS matter. In an environment such as a wind or an accretion disk, spectral lines may form over a relatively large volume, and the field topology may therefore be complex not only in latitude and azimuth, but in radius as well. Dynamical plots of the Hbeta line show an intriguing very complex structure with appearing and disappearing absorption features, which can be related to the complex morphology of the CS matter with asymmetric dust clump structures. The profiles of spectral lines belonging to different elements are variable, indicating the presence of chemical spots.

Accurately predicting eclipse events around irregular small bodies is crucial for spacecraft navigation, orbit determination, and spacecraft systems management. This paper introduces a novel approach leveraging neural implicit representations to model eclipse conditions efficiently and reliably. We propose neural network architectures that capture the complex silhouettes of asteroids and comets with high precision. Tested on four well-characterized bodies - Bennu, Itokawa, 67P/Churyumov-Gerasimenko, and Eros - our method achieves accuracy comparable to traditional ray-tracing techniques while offering orders of magnitude faster performance. Additionally, we develop an indirect learning framework that trains these models directly from sparse trajectory data using Neural Ordinary Differential Equations, removing the requirement to have prior knowledge of an accurate shape model. This approach allows for the continuous refinement of eclipse predictions, progressively reducing errors and improving accuracy as new trajectory data is incorporated.

With the launch of the Fermi-LAT observatory in 2008, more new gamma-ray objects were discovered, mostly dominated by blazars. In addition, some of the narrow line Seyfert 1 (NLSy1) galaxies were observed in gamma-ray but in less number, making them different from other NLSy1 galaxies. We studied the six gamma-ray-detected NLSy1 galaxies using the hard X-ray observations from NuSTAR and optical g- & r-band from ZTF. The X-ray spectra corresponding to all objects are well-fitted with a power-law spectral model, and a strong "brighter-when-redder" trend is seen, which is the properties mostly seen in Blazars. The X-ray light curves were produced for all the available observations, and the F$_{var}$ is estimated for all the observations. In 1H 0323+342, we found that F$_{var}$ lies between 9-22%, suggesting significant variability in the same source. Similarly, for PKS 2004-447, we found F$_{var}$ lies between 10-21%. We see a strong X-ray and gamma-ray spectral index correlation among these objects, suggesting that X-rays and gamma-rays are produced through a similar process. Comparing the X-ray spectral index with other class objects, we see that NLSy1 galaxies are similar to LBL and IBL types. We see a negative trend of X-ray flux with the gamma-ray luminosity in these objects, suggesting an anti-correlation between X-ray and gamma-ray luminosity. A similar trend is seen between the X-ray flux, total jet power, and disk luminosity. The X-ray spectral index also shows a negative trend with total jet power and disk luminosity. The optical variability amplitude lies between 0.90 to 2.32, and the fractional variability varies from 13-40%. The color-magnitude plot shows mostly the brighter-when-redder trend, suggesting $\gamma$-NLSy1 are much closer to FSRQs than BL Lacs. Our results, overall, summarize how the various parameters in gamma-ray-detected NLSy1 are connected.

We present the Bayesian Global Sky Model (B-GSM), a new absolutely calibrated model of the diffuse Galactic foreground at frequencies below 408 MHz. We assemble a dataset of publicly available diffuse emission maps at frequencies between 45 MHz and 408 MHz, along with absolute temperature data from the EDGES radiometer between 40 and 200 MHz. We use nested sampling to perform a joint Bayesian analysis of these two datasets and determine posterior distributions of: spatially resolved diffuse components, spectral parameters for the diffuse emission, and calibration corrections for each observed map. Using Bayesian model comparison, we find that the low-frequency sky is optimally modelled by two emission components, each following a curved power-law spectrum. The spectrum for the first component has a spectral index of beta_1 = -2.633 plus/minus 0.002 and a curvature of gamma_1 = 0.014 plus/minus 0.001, while the second has beta_2 = -2.108 plus/minus 0.008 and gamma_2 = -0.424 plus/minus 0.008. The diffuse maps require temperature-scale corrections of 1% to 29%, and zero-level adjustments of a few kelvin to a few hundred kelvin. We find that the Haslam 408 MHz map is well calibrated, requiring a scale correction of 1.029 plus/minus 0.003 (about 3%) and a zero-level correction of 0.91 plus/minus 0.05 kelvin. Posterior predictions for the sky's absolute temperature are in excellent agreement with EDGES data, indicating accurate calibration. The posterior sky predictions agree with observations within statistical uncertainty across all frequencies. However, agreement varies by position, with the largest discrepancies in the Galactic plane. This is the second paper in the B-GSM series; the low-frequency sky model, along with all code and data, is available for download.

Context. Vela X-1 is among the earliest discovered high-mass X-ray binary (HMXB) pulsars. In such systems, the companion's stellar wind is strongly affected by ionisation from X-rays emitted by the compact object. A smooth, isotropic stellar wind model cannot account for the observed orbital variation in absorption column density. A stream-like photoionisation wake trailing the neutron star has been proposed to explain this variation. Aims. We investigated the variability of the circumbinary environment at different intensity levels of the Vela X-1 and used a model similar to the above-mentioned stream-like photoionisation wake to explain the asymmetric absorption column density present in the source. Methods. The 2.0-20.0 keV MAXI/GSC spectrum was well modelled with a Comptonised continuum absorbed by local and interstellar material. Nearly 13 years of MAXI/GSC data was used to constrain the variations in absorption column density in Vela X-1 from orbital-phase and intensity-and-orbital-phase resolved spectroscopy. Results. The long-term light curve of Vela X-1 shows orbit-to-orbit intensity level variations without any apparent super-orbital periodicity. The orbital-phase resolved spectroscopy in multiple intensity levels reveals asymmetric variation in absorption column density changes across the intensity levels. Conclusions. We confirm that the orbital variation in absorption column density in Vela X-1 cannot be explained by a smooth stellar wind alone using long-term MAXI/GSC data. An additional component, such as a photoionisation or accretion wake, is required. The wake structure is present across intensity levels, with geometry varying by intensity. The long-term MAXI/GSC data enabled us to vary wake parameters and derive best-fit stellar wind parameters for the time-averaged intensity, reproducing observed absorption column density across intensity levels. (Abbreviated.)

this http URL is the second paper of a series aiming to determine the birth rates of supernovae in the local Universe. Aims. In this paper, we aim to estimate the SN rates in the local universe and fit the delay-time distribution of SNe Ia to put constraints on their progenitor scenarios. this http URL performed a Monte-Carlo simulation to estimate the volumetric rates with the nearby SN sample introduced in Paper I of the series. The rate evolution of core-collapse SNe well traces the evolution of cosmic star formation history; while that of SNe Ia involves the convolution of cosmic star-formation history and a two-component delay-time distribution including a power law and a Gaussian component. this http URL volumetric rates of type Ia, Ibc and II SNe are derived as $0.325\pm0.040^{+0.016}_{-0.010}$, $0.160\pm0.028^{+0.044}_{-0.014}$, and $0.528\pm0.051^{+0.162}_{-0.013}$ (in unit of $10^{-4} yr^{-1} Mpc^{-3} h^3_{70}$), respectively. The rate of CCSNe is consistent with previous estimates. The newly derived local SN Ia rate is larger than existing results given at redshifts 0.01 < z < 0.1, favoring an increased rate from the universe at z ~ 0.1 to the local universe. A two-component model can well fit the rate variation, with the power law component accounting for the rate evolution at larger redshifts and the Gaussian component with a delay time of 12.63$\pm$0.38 Gyr accounting for the local rate evolution. This delayed component with such a longer delay time suggests that the progenitors of these SNe Ia were formed at around 1 Gyr after the birth of the universe, which could only be explained by a double-degenerate progenitor scenario. This is evidenced by the comparison with the PTF sample of SNe Ia at z = 0.073, which reveals that the increase in SN Ia rate at z < 0.01 is primarily due to the SNe Ia of massive E and S0 galaxies with old stellar populations.

Double white dwarf binaries are a leading explanation to the origin of type Ia supernovae, but no system exceeding the Chandrasekhar mass limit (1.4 M$_\odot$) has been found that will explode anywhere close to a Hubble time. Here, we present the super-Chandrasekhar mass double white dwarf WDJ181058.67+311940.94 whose merger time ($22.6\pm1.0$ Gyr) is of the same order as a Hubble time. The mass of the binary is large, combining to $1.555\pm0.044$ M$_\odot$, while being located only 49 pc away. We predict that the binary will explode dynamically via a double detonation destroying both stars just before they merge, appearing as a subluminous type Ia supernova with a peak apparent magnitude of about $m_V=-16$ (200,000 times brighter than Jupiter). The observationally-derived birthrate of super-Chandrasekhar mass double white dwarfs is now at least $6.0\times10^{-4}$ yr$^{-1}$ and the observed rate of type Ia supernovae in the Milky Way from such systems is approximately $4.4\times10^{-5}$ yr$^{-1}$, while the predicted type Ia supernova rate in the Milky Way from all progenitor channels is about sixty times larger. Hence, WDJ181058.67+311940.94 mitigates the observed deficit of massive double white dwarfs witnessed in volume-complete populations, but further evidence is required to determine the majority progenitors of type Ia supernovae.

Recently, the LHAASO Collaboration reported the first very-high-energy gamma-ray catalog, containing 90 TeV sources. Among these sources, 1LHAASO J1929+1846u is located 0.3$^\circ$ west of SNR G54.1+0.3 and also lies within a $+53 \, \text{km s}^{-1}$ cloud (the Western Cloud). Moreover, one of the IceCube track-type high-energy starting events is found around 1.3$^\circ$ north of 1LHAASO J1929+1846u, which may serve as strong evidence for the hadronic origin of this TeV source. SNR G54.1+0.3 is a young supernova remnant (SNR), with a powerful pulsar wind nebula (PWN) inside. Its X-ray radiation from the PWN and the SNR Shell can be clearly identified. The radio emission from the PWN region is also given. However, given the angular resolution of gamma-ray experiments, the entire SNR region is viewed as a point source by Fermi-LAT, H.E.S.S. and VERITAS. In this work, we explore a hybrid scenario where SNR G54.1+0.3 is indeed associated with the Western Cloud, and we derive the multi-wavelength emissions from the PWN, the SNR Shell, and the Western Cloud, separately. Our model can explain the observations well, indicating that SNR G54.1+0.3 might be an excellent candidate of Galactic PeVatron and neutrino source.

Galaxy clusters are powerful laboratories for studying both cosmic structure formation and galaxy evolution. We present a comprehensive analysis of the velocity anisotropy profile, beta(r), in galaxy clusters using the Uchuu-UniverseMachine mock galaxy catalog, which combines the large-volume Uchuu N-body simulation with the UniverseMachine galaxy formation model. Focusing on clusters with log(M200) >= 13.9 [h^-1 M_sun] up to redshift z = 1.5, we investigate the behavior of beta(r) as a function of cluster-centric radius, mass, and redshift. We find that beta(r) exhibits a universal shape: it rises from isotropic values near the cluster core, peaks at approximately 1.7 R200, declines around 3.4 R200 due to orbital mixing, and increases again in the outskirts due to the dominance of first-infalling galaxies. Our results show that more massive clusters have higher radial anisotropy and larger peak beta values. Moreover, beta(r) evolves with redshift, with high-redshift clusters displaying more radially dominated orbits and enhanced infall motions. We further derive redshift-dependent power-law scaling relations between M200 and key physical radii: hydrostatic (R_hs), infall (R_inf), and turnaround (R_ta). These findings offer a robust theoretical framework for interpreting the dynamical properties of observed galaxy clusters and provide key insights into the evolution of their dynamical state over cosmic time.

We report the first spectro-polarimetric investigation of the bright Z-type source GX 349+2 using simultaneous observations of \textit{IXPE}, \textit{NuSTAR} and \textit{Swift/XRT}. The source exhibited significant polarization in the 2-8 keV energy range during the flaring branch (FB) and normal branch (NB). The estimated polarization degree (PD) and polarization angle (PA) for FB are $1.74 \pm 0.52\%$ ($3.3\sigma$) and $19.4 \pm 8.9^\circ$, respectively; while for NB, PD and PA are $0.8 \pm 0.22\%$ ($3.6\sigma$) and $35.4 \pm 7.9^\circ$, respectively. The energy-resolved polarization for NB revealed an increase in PD from $0.78\pm0.2\%$ ($3.6\sigma$) to $1.32\pm0.40\%$ ($3.3\sigma$) and a change in PA from $17.9\pm8.1^\circ$, and $53.2\pm8.6^\circ$, in the energy range of 2-4 and 4-8 keV, respectively. Using the simultaneous observations of \textit{Swift/XRT} and \textit{NuSTAR}, we investigated the spectral properties of the source during NB, and the Western model well explained it. The spectra also depicted a strong and broad Fe K$\alpha$ line. However, spectro-polarimetric analyses carried out by \textit{IXPE} align closely with model-independent polarimetric results. We discuss results obtained from the polarimetric studies in the context of various coronal geometries, and we confirm the slab-like geometry in the NB for GX 349+2.

Over the past century, supernova (SN) searches have detected multiple supernovae (SNe) in hundreds of individual galaxies. So-called SN siblings discovered in the same galaxy present an opportunity to constrain the dependence of the properties of SNe on those of their host galaxies. To investigate whether there is a connection between sibling SNe in galaxies that have hosted multiple SNe and the properties of galaxies, we have acquired integrated optical spectroscopy of 59 galaxies with multiple core-collapse SNe. Perhaps surprisingly, a strong majority of host-galaxy spectra fall within the composite region of the Baldwin-Phillips-Terlevich (BPT) diagram. We find a statistically significant difference (KS test p-value = 0.044) between the distributions of the [NII] $\lambda$6583/H$\alpha$ of galaxies that have hosted a majority SN Ibc and those that have hosted a majority SN II, where the majority SN Ibc galaxies have, on average, higher ratios. The difference between the distributions of [NII] $\lambda$6583/H$\alpha$ may arise from either increased contribution from AGN or LINERs in SN Ibc host galaxies, greater metallicity for SN Ibc host galaxies, or both. When comparing the inferred oxygen abundance and the ionization parameter for the galaxies in the Star-Forming region on the BPT diagram, we find statistically significant differences between the distributions for SN Ibc hosts and SN II hosts (p=0.008 and p=0.001, respectively), as well as SN Ib hosts and SN II hosts (p=0.030 and p=0.006, respectively). We also compare the H$\alpha$ equivalent width distributions, also integrated across the galaxies, and find no significant difference.

X-ray quasi-periodic oscillations (QPOs) are commonly observed in Galactic X-ray binaries (XRBs) and extragalactic ultraluminous X-ray sources (ULXs). In this study, we perform a phase-resolved analysis of recently discovered X-ray millihertz QPOs in M51 ULX-7. This represents the first detailed phase-resolved analysis of QPOs conducted in ULXs. Our findings reveal that the amplitude of the mHz QPO slightly increases with photon energy, accompanied by a narrowing of the phase modulation profile. The phase-resolved spectroscopy indicates significant variability in the energy spectrum: both disk blackbody components exhibit marked variations on the QPO timescale, with the low-temperature component demonstrating significant synchronous changes in the disk temperature and luminosity, showing a positive correlation between these two parameters throughout the QPO cycle. This correlation supports the hypothesis that the disk inner radius corresponds to the magnetospheric radius, which slightly varies with the accretion rate. Our results suggest that the soft component, without beaming, originates from a magnetically truncated outer disk, while the hard component is geometrically beamed from the inner funnel regions.

Baryon acoustic oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI) appear to indicate the first evidence for dynamical dark energy (DDE), with a present-day behavior resembling quintessence. This evidence emerges when the Chevallier-Polarski-Linder (CPL) parametrization of the dark energy equation of state, $w_{\textrm{de}} = w_0 + w_a (1-a)$, is considered, and persists across other functional forms of $w_{\textrm{de}}$. In this work, we investigate how the inclusion of future gravitational wave (GW) standard siren data impacts the uncertainties in cosmological parameters when combined with DESI measurements. Specifically, we analyze the expected contributions from three upcoming GW observatories: the Einstein Telescope (ET), the Deci-hertz Interferometer Gravitational-wave Observatory (DECIGO), and the Laser Interferometer Gravitational-Wave Observatory (LIGO). We find that the addition of GW data, particularly from LIGO and DECIGO, significantly reduces the uncertainties in cosmological parameters, with the extent of the improvement depending on the specific form of $w_{\textrm{de}}$. Our results highlight both the constraining power of future GW observations and the importance of considering a range of cosmological models in data analysis.

Magnetic reconnection is a fundamental mechanism of driving eruptive phenomena of different scales and may be coupled with turbulence as suggested by recent remote-sensing and in-situ observations. However, the specific physics behind the complex three-dimensional (3D) turbulent reconnection remains mysterious. Here, we develop a novel methodology to identify and analyze multitudes of multi-scale reconnection fragments within a strongly turbulent current sheet (CS) and apply it to a state-of-the-art numerical simulation of turbulent reconnection for solar flares. It is determined that the reconnection fragments tend to appear as quasi-2D sheets forming along local magnetic flux surfaces, and, due to strong turbulence, their reconnection flow velocities and reconnection rates are significantly broadened statistically but are scale-independent. Each reconnection fragment is found to be surrounded by strongly fluctuated in/out-flows and has a widely distributed reconnection rate, mainly in the range of 0.01-0.1. The results, for the first time, provide quantitative measurements of 3D magnetic reconnection in strongly turbulent flare CSs, offering insights into the cascading laws of 3D reconnection in other turbulent plasmas.

We present a statistical analysis of Ly$\alpha$ absorption using 581 galaxies at $z=4.5$-13 observed with multiple JWST/NIRSpec spectroscopy programs, including JADES, UNCOVER, CEERS, and GO/DDT. We carefully construct composite spectra binned by redshift with homogeneous UV properties (UV magnitudes, UV slopes, and Ly$\alpha$ equivalent widths) and identify significant Ly$\alpha$ forest signals in galaxies at $z\sim5$-6, which diminish toward higher redshifts. We also find UV continuum breaks at rest-frame 1216Å that soften beyond $z\gtrsim6$, confirming the effects of cosmic reionization through a self-consistent transition from Gunn-Peterson to Ly$\alpha$ damping wing absorption in galaxies. Fair comparisons of composite spectra with matched UV magnitudes and slopes across redshift reveal that UV-faint galaxies clearly show stronger Ly$\alpha$ absorption than UV-bright galaxies towards high redshift, providing insights into the topological evolution of reionization. We estimate Ly$\alpha$ transmission at the Gunn-Peterson trough and Ly$\alpha$ damping wing absorption by comparing the galaxy spectra to low-$z$ ($z\sim2$-5) galaxy templates that include galactic and circumgalactic absorption and Ly$\alpha$ emission. Using these measurements together with reionization simulations, we derive volume average neutral hydrogen fractions of $\langle x_{\rm HI} \rangle$ = ${0.00}^{+0.12}_{-0.00}$, ${0.25}^{+0.10}_{-0.20}$, ${0.65}^{+0.27}_{-0.35}$, ${1.00}^{+0.00}_{-0.20}$, and ${1.00}^{+0.00}_{-0.40}$ at $z\sim5$, 6, 7, 9, and 10, respectively. These values align with a reionization history characterized by a rapid transition around $z\sim7$-8, consistent with Ly$\alpha$ emitter observations. While the physical driver of this rapid reionization remains unclear, it may involve the emergence of hidden AGN populations and/or the onset of Lyman-continuum escape from galaxies.

The surface magnetic fields of pre-main-sequence stars and zero-age main-sequence stars are notably strong, resulting in the generation of numerous spots and the emission of bright chromospheric lines. Rotational variations in magnetic field strength have been identified in T Tauri stars (TTSs) and young main-sequence stars using Zeeman--Doppler imaging. This study investigates the relationship between the mean values and variation amplitudes of the magnetic field strengths of TTSs, main-sequence stars, and the Sun. The findings reveal a positive correlation of over three orders of magnitude, suggesting that a common mechanism drives the magnetic fields of these stars. This positive correlation implies that stars with larger spot sizes experience greater variation amplitudes due to rotational modulations. For the Sun, both the mean magnetic field strength value and its variation amplitude tend to be higher during solar maximum than during solar minimum.

Microquasars are the compact objects generally including accreting black holes which produce relativistic jets. The physical mechanisms of jet launching, collimation, and acceleration are poorly understood. Microquasars show strong variability in multi-wavelength observations. In X-rays, the sources show the fast variation features down to millisecond time scales, with the prominent quasiperiodic oscillations (QPOs) around 0.1 Hz - tens of Hz in light curves, however, physical origin of QPOs is still uncertain. FAST as the largest radio telescope provides the opportunity to study fast variability of both radio flux and polarization in microquasars. In the FAST observations from 2020 - 2022, we reported the first evidence of radio subsecond quasi-periodic oscillations of GRS 1915+105, providing the direct link between QPOs and the dynamics of relativistic jets. These QPOs with the centroid frequency around 5 Hz are transient, accompanied with strong evolution of the spectral index. Combined with multiwavelength observations, we discuss the possible physical models to produce radio QPOs in BH systems: the helical motion of jet knots or precession of the jet base. In near future, high time resolution radio monitoring of microquasars based on FAST is expected to discover more new phenomena in black hole systems, which will be important to understand the physics in strong gravity.

Optical transients with timescale of months, such as supernovae (SNe) and tidal disruption events (TDEs), are candidates of high-energy neutrino sources. Multiple neutrino detections from the same direction within a month timescale provide a unique opportunity to identify such optical counterparts in the nearby Universe. In this work, we conduct archival search for the optical counterpart of an IceCube triplet event using the data of Zwicky Transient Facility. We develop a dedicated alert filtering system and validate the performance by following a blind analysis method. Applying this filtering system to the data after the detections of the IceCube triplet event, we find no transient candidates within the localization area. Assuming that the IceCube triplet event originates from an astrophysical source, we constrain parameters of optical transient, a peak luminosity and a decay timescale, using a simple signal model that is motivated by TDEs and superluminous SNe (SLSNe). Assuming the case with no time lag between neutrino detections and optical peak, almost entire parameter space of the known TDEs and SLSNe would be constrained. To give constraints on transients with a rapidly evolving light curve, quick follow-up observations for future neutrino multiplet events are crucial.

We present a multi-wavelength study of the filamentary cloud G47 (d $\sim$4.44 kpc), which hosts the mid-infrared bubbles N98, B1, and B2. The SMGPS 1.3 GHz continuum map detects ionized emission toward all the bubbles, marking the first detection of ionized emission toward the B2 bubble. Analysis of the unWISE 12.0 $\mu$m image, Spitzer 8.0 $\mu$m image, and the Herschel column density and temperature maps reveals two previously unreported hub-filament system candidates associated with the HII regions B2 and N98, which are powered by massive OB stars. This indirectly favours the applicability of a global non-isotropic collapse (GNIC) scenario for massive star formation in N98 and B2. The position-position-velocity diagram of FUGIN $^{13}$CO(1-0) shows significant velocity variations from 61 to 53 km s$^{-1}$ toward areas between B2 and N98, where the magnetic field morphology exhibits significant curvature, and high velocity dispersion (i.e., 2.3--3.1 km s$^{-1}$) is observed. This may be explained by the expansion of the HII regions B2 and N98. The energy budget of the cloud, estimated using SOFIA/HAWC+ and molecular line data, suggests that the magnetic field dominates over turbulence and gravity in G47. Furthermore, the radial column density and velocity profiles of G47 display signatures of converging flows in a sheet-like structure. The relative orientations between the magnetic field and local gravity suggest that G47 may undergo gravitational contraction along the magnetic field lines once it becomes magnetically supercritical.

We present an X-ray spectral analysis of a black hole X-ray binary SLX 1746-331 during the 2023 outburst using five \textit{Insight}-HXMT observations. We jointly use the reflection model \texttt{relxillcp} and the general relativistic thermal thin disk model \texttt{kerrbb} to fit the spectra from 2 - 100 keV. By jointly fitting the five spectra, we constrained the black hole mass to be $M=5.8\pm 0.3 M_{\odot}$ and dimensionless spin parameter to be $a_{*}=0.88^{+0.01}_{-0.02}$ (90 percent statistical confidence). The reflection model shows that SLX 1746-331 is a high-inclination system with the inclination angle $i=63.7^{+1.3}_{-1.0}$ degrees, the accretion disk has a density $\rm{log}N\sim 16 ~\rm cm^{-3}$. In addition, with the different reflection model \texttt{relxilllp}, which assumes a lamp-post geometry corona, we still give similar results.

Rapid X-ray variability of GX 339$-$4 including the low-frequency quasi-periodic oscillations (LFQPOs) and broad-band noises have been observed with the Hard X-ray Modulation Telescope (\textit{Insight}-HXMT) and Neutron star Interior Composition Explorer (\textit {NICER}) during the 2021 outburst. Here we present a systematic study of the evolution and energy dependence properties of such broad-band noises (BBN). The outburst from February to March of 2021 can be divided into three stages: the low hard state (LHS), the hard intermediate state (HIMS) and soft intermediate state (SIMS). In the PDSs of the LHS and HIMS, the broad-band noises are well fitted with three Lorentzian components: a low-frequency component $L_1$, a middle-frequency component $L_2$ and a high-frequency component $L_3$. The increasing trend of the characteristic frequencies for $L_1$ and $L_2$ and the relation between the QPO frequency and characteristic BBN frequency are reported. We found that the energies corresponding to the peaks and shapes of the rms spectra for three BBN components are different. The comparison among three BBN components indicates that energy-dominant bands of these BBN components are distinct. Our results can be explained with the truncated disc/hot flow model with a large variable disc and a small hot inner flow. A possible description of the accretion structure and its evolution from the LHS to the SIMS is proposed. Further research is still required to probe such accretion structure in GX 339--4.

X-ray polarimetry of accreting compact object has revealed fast time variations in the polarization angle (PA), suggesting that the geometry and/or optical depth of the corona is changing rapidly. This prompts investigations into how fast such variability can be. Conventionally, the data are often binned to examine the time variability such that the measurement in each bin is above the minimum detectable polarization (MDP). Here we demonstrate that this is unnecessary, and even below the MDP, one can infer the posterior distribution of PA reliably using the Bayesian approach and still be able to place useful constraints on the physics in many cases. With this approach, we discovered that the PA variation in one of the Imaging X-ray Polarimetry Explorer (IXPE) observations of GX 13+1 is not following a linear rotation mode as suggested previously. Instead, the PA swings between two discrete angles, suggesting that there are two emitting components, e.g., the boundary layer and the spreading layer, competing with each other. Also in one of the observations of GX 13+1 and Sco X-1, the PA is found to vary in correlation with the source count rate, indicating that the mass accretion rate is shaping the corona properties. Also, during the IXPE observation of Sco X-1, the PA in highest flux level seems to deviate from the averaged value and appear to be consistent with previous measurement results with PolarLight and OSO-8.

We present the multi-wavelength study of the ejection of a plasma blob from the limb flare SOL2023-12-31T21:36:00 from NOAA 13536 observed by the Solar Ultraviolet Imaging Telescope (SUIT) on board Aditya-L1. We use SUIT observations along with those from Atmospheric Imaging Assembly (AIA) on board SDO and Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter to infer the kinematics and thermal nature of the ejected blob and its connection to the associated flare. The observations show that the flare was comprised of two eruptions. The blob was ejected during the first eruption and later accelerated to velocities over 1500 km/s measured at a maximum projected height of ~ 178 Mm from the Sun's surface. The acceleration of the ejected plasma blob is co-temporal with the bursty appearance of the hard X-ray light curve recorded by STIX. Radio spectrogram observations from STEREO-A/WAVES and RSTN reveal type III bursts at the same time, indicative of magnetic reconnection. DEM analysis using AIA observations suggests the plasma blob is comprised of cooler and denser plasma in comparison to the ambient corona. To the best of our knowledge, this is the first observation of such a plasma blob in the NUV, providing crucial measurements for eruption thermodynamics.

The mergers of binary neutron stars (BNSs) and neutron star-black holes (NSBHs) binaries have long been linked to short-duration gamma-ray bursts (SGRBs). However, despite their stellar progenitors, SGRBs are often found outside the stellar light of the host galaxy. This is commonly attributed to supernova kicks, which displace the SGRB progenitors from the original stellar population. Our goal is to use stellar population synthesis models to reproduce and interpret the observed offsets of a statistical sample of SGRBs, using realistic galactic models based on the observed host properties. We derive the host galaxy potentials from the observed properties on a case-by-case basis, and simulate the galactic trajectories of synthetic BNSs and NSBHs from the BPASS code using three different kick prescriptions. We compare predicted and observed offsets to investigate the impact of velocity kicks, host galaxy types, and host association criteria. The results confirm that the locations of the SGRB population are consistent with the expectations of kicked BNS or BHNS progenitors, implying that such mergers are the dominant (if not only) progenitor system. Predictions for NSBHs provide a significantly worse fit compared to BNSs, while we find no significant difference when comparing different kick prescriptions. For late-type hosts, we find the best agreement when including hosts with a probability of chance alignment Pch up to 20%, while lower Pch thresholds lead us to overestimate SGRB offsets. We argue that Pch is biased against viable hosts at the largest offsets, and suggest the use of less conservative Pch thresholds for late-type hosts. For early-type hosts, the predictions underestimate SGRB offsets in a few cases regardless of the Pch threshold applied. We argue that this is likely due to the models missing galaxy evolution, or spurious host associations.

The era of time domain multi-messenger (MM) astrophysics requires sensitive, large field-of-view (FoV) observatories that are able to quickly react in order to respond to alerts from gravitational wave (GW) triggers, neutrino detections, and transient sources from all parts of the electromagnetic (EM) spectrum. This is particularly true at hard X-rays and soft gamma-rays where the EM counterparts to GW triggers, gamma-ray bursts (GRBs), emit most of their flux. While the present decade has a number of instruments capable of accomplishing this task, there are no missions planned for the 2030's when improved MM facilities will detect many more events. It is in this context that we present the GRINTA mission concept. GRINTA has a large area, large FoV detector to search for short, impulsive events in the 20 keV - 10 MeV energy range and a coded mask telescope for localizing and performing follow-up observations of sources from 5-200 keV. While GRINTA's main scientific goal is studying MM events, the instruments will observe numerous other sources to explore the sky at hard X-rays/soft gamma-rays.

The relationship between the mass-loss history and final evolutionary stage of massive stars and the properties of the observable supernova (SN) is still under debate. This is especially true for stripped-envelope (Type Ib/c) SNe, where the progenitor ejects a considerably large amount of material during its evolution, which can lead to a circumstellar medium relatively close to the exploding star. Moreover, when the star explodes as a SN, this matter may contribute significantly to the generated luminosity because of the interaction. However, the trace of this circumstellar interaction can only be investigated for a couple of Type Ib/c SNe, and the nature of a close (within around $10^{15}$ cm) circumstellar matter (CSM) has also been largely unexplored for these objects. Here, we present the results of our radio and bolometric light curve (LC) analysis related to SN 2004gq. We describe a combined model that explains the unusual LC properties of this event and supports the circumstellar interaction scenario. For that, we computed the quasi-bolometric LC of the SN and fit this with a multicomponent model to gain information on the progenitor and the surrounding circumstellar medium. We also analyzed the available radio LCs (taken at 1.4,\ 4.9 and 8.5 GHz) of SN 2004gq to verify our estimated average mass-loss rate, which is one of the most crucial physical properties related to CSM models. We infer reasonable parameters for SN 2004gq using radioactive decay and magnetar energy input. To power the entire LC, we must also add an extra energy source related to the CSM. We determine the most essential parameter of this medium: the average mass-loss rate from both LC and radio data fitting. We find that the suggested hidden circumstellar interaction is a viable mechanism that provides the required energy deficiency and that it can be estimated using a simple semi-analytic model.

This paper focuses on observing unstudied Galactic open clusters in the Ultraviolet (UV) wavelength range and analyzing their photometric data. The Gaia Data Release 3 (DR3) enables us to precisely study known Galactic open clusters. We conducted observations using the 1.54-meter Danish Telescope (DK1.54) in Chile and the 2.15-meter telescope at the Complejo Astron{ó}mico El Leoncito (CASLEO) in Argentina, employing UV filters. Furthermore, we have collected available photometric and astrometric data for our observed clusters. We aim to estimate the reddening of Galactic open clusters using UV photometry. We applied isochrone fitting to determine the reddening of the clusters using well-known members. As a final result, we present the reddening values of 105 Galactic open clusters in the UV, as determined by our photometry.

Numerous experiments have been designed to investigate the Cosmic Dawn (CD) and Epoch of Reionization (EoR) by examining redshifted 21-cm emissions from neutral hydrogen. Detecting the global spectrum of redshifted 21-cm signals is typically achieved through single-antenna experiments. However, this global 21-cm signal is deeply embedded in foreground emissions, which are about four orders of magnitude stronger. Extracting this faint signal is a significant challenge, requiring highly precise instrumental calibration. Additionally, accurately modelling receiver noise in single-antenna experiments is inherently complex. An alternative approach using a short-spacing interferometer is expected to alleviate these difficulties because the noise in different receivers is uncorrelated and averages to zero upon cross-correlation. The Short-spacing Interferometer array for Global 21-cm Signal detection (SIGMA) is an upcoming experiment aimed at detecting the global CD/EoR signal using this approach. We describe the SIGMA system with a focus on optimal antenna design and layout, and propose a framework to address cross-talk between antennas in future calibrations. The SIGMA system is intended to serve as a prototype to gain a better understanding of the system's instrumental effects and to optimize its performance further.

We present the first computation of the gravity model testing parameter $E_G$ on realistic simulated modified gravity galaxy mocks. The analysis is conducted using two twin simulations presented in arXiv:1805.09824(1): one based on general relativity (GR) and the other on the $f(R)$ Hu $\&$ Sawicki model with $f=10^{-5}$ (F5). This study aims to measure the $E_G$ estimator in GR and $f(R)$ models using high-fidelity simulated galaxy catalogs, with the goal of assessing how future galaxy surveys can detect deviations from standard gravity. Deriving this estimator requires precise, unbiased measurements of the growth rate of structure and the linear galaxy bias. We achieve this by implementing an end-to-end cosmological analysis pipeline in configuration space, using the multipoles of the 2-point correlation function. Our analysis demonstrates how to measure the scale-dependent growth rate predicted by non-standard gravity models. We split the estimation of the RSD $\beta$ parameter over distinct scale ranges, separating large (quasi-linear) and small (non-linear) scales. We show that this estimator can be accurately measured using mock galaxies in low redshift bins ($z < 1$), where it offers strong discriminating power over competing gravity theories. We find that, for an all-sky galaxy survey and neglecting observational systematics, accurate and largely unbiased estimations of $E_G$ can be obtained across all redshifts. However, the error bars are too large to clearly distinguish between the theories. When measuring the scale-dependence of the $E_G$ estimator, we note that state-of-the-art theory modeling limitations and intrinsic "prior volume effects" prevent high-accuracy constraints. Alternatively, we propose a null test of gravity using RSD clustering, which, if small scales are modeled accurately in future surveys, could detect significant departures from GR.

Recent findings suggest a universal relationship between the quasi-periodic sub-structures and rotational periods across various types of radio-emitting neutron stars. In this study, we report the detection of 12 quasi-periodic sub-structures in a rotating radio transient (RRAT) J1913+1330 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). This is the second known RRAT exhibiting quasi-periodic sub-structures. Our result reinforces the observed relationship between quasi-periodicity and rotational period. The polarization analysis reveals that 11 of the 12 pulses exhibit high linear polarization consistent with the quasi-periodic behaviour of the total intensity, while circular polarization with detectable quasi-periodic sub-structures is observed in only three pulses. No correlation is found between the sub-structure periods and their widths, peak fluxes, or fluences, even under the extremely variable single-pulse energy and morphology observed in J1913+1330.

We propose SILVIA (Space Interferometer Laboratory Voyaging towards Innovative Applications), a mission concept designed to demonstrate ultra-precision formation flying between three spacecraft separated by 100 m. SILVIA aims to achieve sub-micrometer precision in relative distance control by integrating spacecraft sensors, laser interferometry, low-thrust and low-noise micro-propulsion for real-time measurement and control of distances and relative orientations between spacecraft. A 100-meter-scale mission in a near-circular low Earth orbit has been identified as an ideal, cost-effective setting for demonstrating SILVIA, as this configuration maintains a good balance between small relative perturbations and low risk for collision. This mission will fill the current technology gap towards future missions, including gravitational wave observatories such as DECIGO (DECihertz Interferometer Gravitational wave Observatory), designed to detect the primordial gravitational wave background, and high-contrast nulling infrared interferometers like LIFE (Large Interferometer for Exoplanets), designed for direct imaging of thermal emissions from nearby terrestrial planet candidates. The mission concept and its key technologies are outlined, paving the way for the next generation of high-precision space-based observatories.

The radiation mechanisms powering Gamma-ray bursts (GRBs) and their physical processes remain one of the unresolved questions in high-energy astrophysics. Spectro-polarimetric observations of exceptionally bright GRBs provide a powerful diagnostic tool to address these challenges. GRB 230307A, the second-brightest long-duration GRB ever detected, exhibits a rare association with a Kilonova, offering a unique and rare probe into the emission processes of GRBs originating from compact object mergers. We present a comprehensive time-averaged and time-resolved spectro-polarimetric analysis of GRB 230307A using joint observations from the $AstroSat$ Cadmium Zinc Telluride Imager (CZTI), the $Fermi$ Gamma-ray Burst Monitor (GBM) and $Konus$-Wind. Spectral analysis reveals a temporal evolution in the low-energy photon index, $\alpha$, transitioning from a hard to a softer state over the burst duration. Time-averaged polarimetric measurements yield a low polarization fraction ($<$ 12.7 %), whereas time-resolved polarization analysis unveils a marked increase in polarization fractions ($>$ 49 %) in the later stages of the emission episode. This spectro-polarimetric evolution suggests a transition in the dominant radiative mechanism: the initial phase characterized by thermal-dominated photospheric emission (unpolarized or weakly polarized) gives way to a regime dominated by non-thermal synchrotron emission (highly polarized). This transition provides critical evidence for the evolving influence of magnetic fields in shaping the GRB emission process and jet dynamics.

Flat Spectrum Radio Quasars (FSRQs) are weak sources of very high energy (VHE; E>100 GeV) emission, despite exhibiting strong MeV-GeV emissions that dominate their radiative output. To date, only ten FSRQs have been detected at VHEs, primarily during bright optical phases. In this study, we perform a detailed and systematic, temporal, and spectral analysis of the nine VHE-detected FSRQs, using the Swift X-ray Telescope (XRT) data. Our findings show no correlation between VHE activity and the X-ray flux or spectral state of the sources. However, investigation of spectral properties with X-ray brightness shows anti-correlation between flux and spectral index. The X-ray, generally with a different spectral shape lies at the farther end of the optical-UV synchrotron spectrum which typically shows a declining power-law spectrum, and thus, the X-ray spectrum is generally explained by Synchrotron Self-Compton (SSC) process. However, if optical-UV synchrotron emission extends into the X-ray band, it can soften the X-ray spectrum. While most sources in our sample exhibit rising X-ray SEDs, indicative of non-synchrotron origins or minimal synchrotron contributions, many display softer or flat X-ray spectra, mainly during low X-ray flux states (e.g., 4C +21.35, 3C 279, TON 0599, PKS 1441+25, and PKS 0346-27) suggesting potential synchrotron contributions. These synchrotron continuations influence the gamma-ray spectrum, implying extension into the VHE range for inverse Compton (IC) scattering in the Thomson scattering limit. If the extended component corresponds to an underlying low-level emission, these FSRQs could represent potential candidates for persistent VHE activity.

Blazars, a unique class of active galactic nuclei, exhibit highly variable emission across the electromagnetic spectrum. This variability frequently manifests as intense flaring events, sparking an ongoing debate in recent literature about whether these flares exhibit periodic behavior in certain sources. However, many blazars also show clear signs of stochastic, uncorrelated flares that do not follow a regular pattern. This paper explores how the presence of one such of these stochastic flares can distort an intrinsically periodic pattern of emission in blazars. Our results demonstrate that, depending on the specific circumstances, the deviations in significance and periods can exceed 100\%. Sometimes, these deviations can be so severe that they eliminate any evidence of a periodic pattern. These findings highlight the dramatic impact that flares can have on periodicity searches. To confront this challenge, we propose an innovative approach, the Singular Spectrum Analysis method, which appears more robust against the effects of flares. As an alternative solution, we also propose the sigma clipping technique to mitigate the impact of flares. This framework offers a valuable foundation for analyzing periodicity in similar astrophysical sources that are also subject to stochastic flaring events.

Annular substructures serve as ideal venues for planetesimal formation. In this series, we investigate the linear stage of dust growth within rings. The first paper examines the global streaming instability, while this study focuses on the dusty Rossby wave instability (DRWI). We perform a linear analysis of the two-fluid equations on a background pressure bump, representing annular substructures. The spectral code \textsc{Dedalus} is used to solve the linear eigenvalue problem. We identify two distinct DRWI modes: Type I, which originates from dust-modified gas RWI, and Type II, which results from dust-gas coupling. These modes never coexist for a given azimuthal wavenumber $\ky$, but transition between each other as $\ky$ varies. Type I modes are driven by the advection of background vorticity, whereas Type II modes involve two primary waves: Rossby waves, driven by advection, and thin waves, driven by dust-gas drag. Finally, we assess the relevance of DRWI in ALMA rings using DSHARP sources. Our findings suggest that Type I modes could explain the absence of azimuthal asymmetries in many ALMA disks, whereas Type II modes are entirely absent in all eight observed rings, implying that unresolved narrow rings or alternative mechanisms may play a role in dust growth within annular substructures.

This paper proposes a non-smooth controller optimization method and shows the results of ongoing research on the implementation of this method for gravitational wave applications. Typical performance requirements concerning these type of suspensions are defined in terms of both H2- and Hinf-type constraints. A non-smooth optimization approach is investigated, which allows the use of non-convex cost functions that are often a result of mixed H2/Hinf optimization problems. Besides the controller, the distribution of the actuation is integrated with the optimization to investigate the feasibility of simultaneous controller and actuator optimization. The results demonstrate that the proposed non-smooth optimization method is able to find suitable solutions for the control and actuator distribution that satisfy all required performance and design constraints.

We present arguments on the likely origins of supernovae without associated host galaxies from open field, non-clustered, environments. We show why it is unlikely these ``hostless'' supernovae stem from escaped hyper-velocity stars (HVS) in any appreciable numbers, especially for core-collapse supernovae. It is highly likely that hostless events arise from dwarf host galaxies too faint to be detected in their parent surveys. Several detections and numerous upper limits suggest a large number of field dwarfs, to $M_V>-14$, which themselves may be important to constraining the slope of the low-mass end of the UV luminosity function, understanding galaxy evolution, and putting $\Lambda$CDM into context. Moreover, the detailed study of these mass and metallicity-constrained host environments, and the variety of supernovae that occur within them, could provide more stringent constraints on the nature of progenitor systems.

The physical processes in the solar corona that shape the solar wind remain an active research topic. Modeling efforts have shown that energy and plasma exchanges near the transition region plays a crucial role in modulating solar wind properties. Although these regions cannot be measured in situ, plasma parameters can be inferred from coronal spectroscopy and ionization states of heavy ions, which remain unchanged as they escape the corona. We introduce a new solar wind model extending from the chromosphere to the inner heliosphere, capturing thermodynamic coupling across atmospheric layers. By including neutral and charged particle interactions, we model the transport and ionisation processes of the gas through the transition region, the corona and into the solar wind. Instead of explicitly modeling coronal heating, we link its spatial distribution to large-scale magnetic field properties. Our results confirm that energy deposition strongly affects wind properties through key mechanisms involving chromospheric evaporation, thermal expansion, and magnetic flux expansion. For sources near active regions, the model predicts significant solar wind acceleration, with plasma outflows comparable to those inferred from coronal spectroscopy. For winds from large coronal holes, the model reproduces the observed anticorrelation between charge state and wind speed. However, the predicted charge state ratios are overall lower than observed. Inclusion of a population of energetic electrons enhances both heavy ion charge states and solar wind acceleration, improving agreement with observations.

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has emerged as the world's premier facility for studying fast radio bursts (FRBs) through its fast transient search backend CHIME/FRB\@. The CHIME/FRB Outriggers project will augment this high detection rate of 2--3 FRBs per day with the ability to precisely localize them using very long baseline interferometry (VLBI). Using three strategically located stations in North America and deploying recently developed synoptic VLBI observing techniques, the Outriggers will provide $\sim 50$~milliarcsecond localization precision for the majority of detected FRBs. This paper presents an overview of the design and implementation of the Outriggers, covering their geographic distribution, structural design, and observational capabilities. We detail the scientific objectives driving the project, including the characterization of FRB populations, host galaxy demographics, and the use of FRBs as cosmological probes. We also discuss the calibration strategies available to mitigate ionospheric and instrumental effects, ensuring high-precision localization. With two stations currently in science operations, and the third in commissioning, the CHIME/FRB Outriggers project is poised to become a cornerstone of the FRB field, offering unprecedented insights into this enigmatic cosmic phenomenon.

We present the synthesis and laboratory rotational spectroscopy of the 7-ring polycyclic aromatic hydrocarbon (PAH) cyanocoronene (C$_{24}$H$_{11}$CN) using a laser-ablation assisted cavity-enhanced Fourier transform microwave spectrometer. A total of 71 transitions were measured and assigned between 6.8--10.6\,GHz. Using these assignments, we searched for emission from cyanocoronene in the GBT Observations of TMC-1: Hunting Aromatic Molecules (GOTHAM) project observations of the cold dark molecular cloud TMC-1 using the 100\,m Green Bank Telescope (GBT). We detect a number of individually resolved transitions in ultrasensitive X-band observations and perform a Markov Chain Monte Carlo analysis to derive best-fit parameters, including a total column density of $N(\mathrm{C}_{24}\mathrm{H}_{11}\mathrm{CN}) = 2.69^{+0.26}_{-0.23} \times 10^{12}\,\mathrm{cm}^{-2}$ at a temperature of $6.05^{+0.38}_{-0.37}\,$K. A spectral stacking and matched filtering analysis provides a robust 17.3$\,\sigma$ significance to the overall detection. The derived column density is comparable to that of cyano-substituted naphthalene, acenaphthylene, and pyrene, defying the trend of decreasing abundance with increasing molecular size and complexity found for carbon chains. We discuss the implications of the detection for our understanding of interstellar PAH chemistry and highlight major open questions and next steps.

A hothouse climate may develop throughout Earth's history and its warming future and on potentially habitable exoplanets near the inner edge of the habitable zone. Previous studies suggested that near-surface atmospheric inversion (NAIV) with planetary boundary air temperature being higher than the air temperature adjacent to the surface, is a pronounced phenomenon in hothouse climates. However, the underlying mechanisms are unclear. Here we show that lower-tropospheric radiative heating is necessary but not independently sufficient in forming the NAIV. Instead, the dynamic heating induced by large-scale subsidence is essential. With the prescribed reasonable large-scale subsidence, NAIV appears in small-domain cloud-resolving simulations, which was not observed in previous studies. Surface evaporative cooling also contributes to the formation of the NAIV. Besides NAIV, we find that surface inversion (SIV) with the air adjacent to the surface being warmer than the underlying sea surface is also a distinct phenomenon in hothouse climates. SIV is caused by strong surface evaporative cooling and large atmospheric shortwave absorption. These two types of inversion strongly stabilize the atmosphere, weaken atmospheric circulation, dry the free troposphere, and suppress the hydrological cycle.

The intrinsic alignments (IA) of galaxies, a key contaminant in weak lensing analyses, arise from correlations in galaxy shapes driven by tidal interactions and galaxy formation processes. Accurate IA modeling is essential for robust cosmological inference, but current approaches rely on perturbative methods that break down on nonlinear scales or on expensive simulations. We introduce IAEmu, a neural network-based emulator that predicts the galaxy position-position ($\xi$), position-orientation ($\omega$), and orientation-orientation ($\eta$) correlation functions and their uncertainties using mock catalogs based on the halo occupation distribution (HOD) framework. Compared to simulations, IAEmu achieves ~3% average error for $\xi$ and ~5% for $\omega$, while capturing the stochasticity of $\eta$ without overfitting. The emulator provides both aleatoric and epistemic uncertainties, helping identify regions where predictions may be less reliable. We also demonstrate generalization to non-HOD alignment signals by fitting to IllustrisTNG hydrodynamical simulation data. As a fully differentiable neural network, IAEmu enables $\sim$10,000$\times$ speed-ups in mapping HOD parameters to correlation functions on GPUs, compared to CPU-based simulations. This acceleration facilitates inverse modeling via gradient-based sampling, making IAEmu a powerful surrogate model for galaxy bias and IA studies with direct applications to Stage IV weak lensing surveys.

The spatial resolution and sensitivity of JWST's NIRCam instrument has revolutionised our ability to probe the internal structure of early galaxies. By leveraging deep medium-band imaging in the Jades Origins Field, we assemble comprehensive spectral energy distributions (SEDs) using 19 photometric bands for over 200 high-redshift galaxies ($z \geq 4.5$). We present an analysis of this sample with particular emphasis on investigating the "outshining" phenomenon, which can bias the inferred stellar populations by masking the presence of evolved stellar populations ($\geq$ 100 Myr) with the light of bright, young O and B-type stars. We address this problem by performing spatially-resolved SED-fitting of both binned and full pixel-by-pixel photometry, which we compare to the traditional integrated approach. We find evidence for systematic underestimation of stellar mass in low-mass galaxies ($\leq 10^9 \rm M_\odot$) with bursty star formation, which can exceed a factor of 10 in individual cases, but on average is typically a factor of 1.25-2.5, depending on the binning methodology and SFH model used. The observed mass offset correlates with burstiness (SFR$_{10 \ \rm Myr}$/SFR$_{100 \ \rm Myr}$) and sSFR, such that galaxies with recently rising SFHs have larger mass offsets. The integrated SFH models which produce the most consistent stellar masses are the double power-law and non-parametric `continuity' models, although no integrated model fully reproduces all resolved SFHs. We apply an outshining correction factor to the Stellar Mass Function at $z=7$, finding little impact within the uncertainties. We conclude that outshining can be important in individual low-mass galaxies, but the overall impact is limited and should be considered alongside other systematic SED fitting effects.

The source OGLE-BLG-DN-0064 (hereafter OGLE64) was classified as a potential dwarf nova based on its regular outburst activity revealed by the OGLE optical survey. In this paper, we investigate the X-ray and optical emissions from the source OGLE64 based on archival Chandra and Swift X-ray data and our optical observations with the 6-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences. OGLE64 shows an X-ray luminosity $ L_X \approx 1.6 \times 10^{32} \, \text{erg s}^{-1} $ and a high X-ray-to-optical flux ratio $ F_X / F_{\text{opt}} \approx 1.5$, typical for accreting white dwarfs. The X-ray spectrum of OGLE64 is better fitted by the models of a power law with a photon index $\Gamma \approx 1.9$ and an optically thin plasma with a temperature $ kT \approx 6.4 \, \text{keV} $. The optical spectrum shows hydrogen and neutral helium emission lines, in some of which a double-peaked structure is observed. An analysis of the outburst activity of OGLE64, based on data from the OGLE, ZTF, ATLAS, and ASAS-SN optical surveys, has revealed superoutbursts with a characteristic supercycle $ P_{\text{super}} \approx 400 \, \text{days} $. We found no significant variability in either the X-ray or optical light curves of OGLE64 that could be associated with the change in the visibility conditions for the emitting regions at different orbital phases. Our estimates of the orbital period of the system by indirect methods show that the period probably lies in the range $ P_{\text{orb}} \sim 1.5 - 3.5 \, \text{h} $. The properties of the X-ray and optical emissions from OGLE64 lead us to conclude that the system is an SU UMa-type dwarf nova.

The scatter of the star-forming main sequence (SFMS) holds a wealth of information about how galaxies evolve. The timescales encoded in this scatter can provide valuable insight into the relative importance of the physical processes regulating star formation. In this paper, we present a detailed observational analysis of the timescales imprinted in galaxy star-formation history (SFH) fluctuations by using the stochastic SFH model to fit 1928 massive, z ~ 0.8 galaxies in the LEGA-C survey. We find that the total intrinsic scatter of the SFMS is ~0.3 dex in galaxies with stellar masses $\gtrsim 10^{10}~\mathrm{M}_\odot$. This scatter decreases as the timescale over which SFRs are averaged increases, declining to a non-negligible ~0.15 - 0.25 dex at 2 Gyr, underscoring the importance of long-timescale SFH diversity to the SFMS scatter. Furthermore, galaxies currently above (below) the SFMS tend to have been above (below) the SFMS for at least ~1 Gyr, providing evidence that individual galaxies may follow different median tracks through SFR$-\mathrm{M}_*$ space. On shorter timescales (~30 - 100 Myr), galaxies' SFRs also vary on the order of ~0.1 - 0.2 dex. Our work supports the idea that the SFMS emerges from a population average of the pathways that individual galaxies trace through the SFR$-\mathrm{M}_*$ plane. The scatter reflects the long-term heterogeneity of these paths likely set by the evolutionary timescales of halo growth and cooling, accentuated by short-term variations reflecting the dynamical timescale of the galaxy and its interstellar medium. Our results emphasize the dynamic nature of the SFMS and the importance of understanding the diverse processes governing star formation.

Europa has been modified by a variety of geologic processes, exposing internally-derived materials that are heavily irradiated by charged particles trapped in Jupiter's magnetosphere. Prior spectral analysis of H2O ice on Europa relied on low signal-to-noise data at wavelengths >2.5 microns, limiting assessment of a 3.1 micron Fresnel peak that is diagnostic of exposed crystalline ice. We report new measurements of H2O ice spectral features using high signal-to-noise data collected by the NIRSpec spectrograph (1.48 - 5.35 microns) on the James Webb Space Telescope. These data reveal a narrow 3.1 micron crystalline H2O ice Fresnel peak, which is primarily located at southern latitudes in Tara and Powys Regiones. Our analysis indicates that crystalline ice exposed in these low-latitude regiones is likely sustained by ongoing thermal (re)crystallization outpacing charged particle amorphization of the top 10 microns of Europa's regolith over short timescales (<15 days). We also measured H2O ice features centered near 1.5 microns, 1.65 microns, and 2.0 microns, and a broad 3.6 micron H2O continuum peak, which are all stronger at northern latitudes, in contrast to the 3.1 micron Fresnel peak identified at southern latitudes. These results support the hypothesis that H2O ice in Europa's regolith is vertically stratified, with amorphous ice grains dominating its exposed surface, except in Tara and Powys Regiones. We also find that a previously detected 4.38 micron 13O2 feature is present almost exclusively at southern latitudes in Tara and Powys Regiones, likely derived from an internal source of carbon-bearing material.

This paper presents a novel approach to four fundamental problems in the field of cosmological perturbation theory. Firstly, the issue of gauge dependence has been addressed by demonstrating the existence of unique and gauge-invariant quantities corresponding to the actual perturbations. Secondly, the formation of primordial structures after decoupling of matter and radiation is dependent on the existence of local fluid flows resulting from local pressure gradients. To take pressure gradients into account, it is necessary to consider both the energy density and the particle number density. Thirdly, the novel relativistic perturbation theory applies to an open, flat, and closed Friedmann-Lemaître-Robertson-Walker universe. The derivation of the novel perturbation theory definitively reveals the inherent limitations of Newtonian gravitation as a framework for investigating cosmological density perturbations. Finally, the application of the perturbation theory to a flat universe demonstrates that, prior to decoupling, perturbations in both Cold Dark Matter and ordinary matter are coupled to perturbations in radiation. Therefore, the universe's earliest structures formed only after decoupling, at which point local nonadiabatic random pressure fluctuations became a significant factor. Negative nonadiabatic pressure fluctuations resulted in a brief, rapid growth of density fluctuations until the total pressure fluctuations became positive. In contrast, positive nonadiabatic pressure fluctuations led to the formation of voids. Perturbations with masses about $2.2\times10^{4}\,\text{M}_\odot$ became nonlinear already $60$ million years after the Big Bang, and perturbations with masses between $6.7\times10^2\,\text{M}_\odot$ and $1.2\times10^6\,\text{M}_\odot$ became nonlinear within about $600$ million years.

The Earth's ionosphere refracts radio signals, shifting the apparent position of radio sources. Wide-field measurements with a radio interferometer can measure the ionospheric distortion. The Murchison Widefield Array (MWA) has the ability to capture ionospheric structures that are smaller than 100 km in extent. We report unusually strong ionospheric activity in MWA data during a magnetic storm on 2023 December 1. The duct-like structure (roughly 50 km $\times$ $>$100 km) passes through the MWA field-of-view (FOV) with a velocity of ~ 100 m/s. The offsets of the apparent position of the radio source are more than 1 degree in the MWA observation data at around 180 MHz. By comparing the Total Electron Content (TEC) data obtained from the GNSS receiver network, we have found that the TEC fluctuations represented by a high Rate of TEC change index (ROTI) coincided with the strong ionospheric activity observed by the MWA. This result suggests that unusual ionospheric signatures detected by the MWA could be caused by plasma bubbles extending across Western Australia during a magnetic storm.

We present a novel approach for implementing baryogenesis via leptogenesis at low scale within neutrino seesaw framework where a sufficient lepton asymmetry can be generated via out of equilibrium CP-violating decays of right handed neutrinos (RHNs) even when their mass falls below the Standard Model (SM) Higgs mass. It becomes possible by keeping the sphaleron in equilibrium below its conventional decoupling temperature $T_{\rm sp}^{\rm SM} \sim131.7$ GeV in SM so as to facilitate the conversion of lepton asymmetry to baryon asymmetry at such a low scale, thanks to the flexibility of the bubble nucleation temperature in case the electroweak phase transition (EWPT) is of first order. The scenario emerges as an exciting (and perhaps unique) possibility for low scale leptogenesis, particularly if the Universe attains a reheating temperature lower than 131.7 GeV. We show that a stochastic gravitational wave, characteristic of such first order EWPT, may be detected in near future detectors while the presence of RHNs of mass as low as 35 GeV opens up an intriguing detection possibility at current and future accelerator experiments.

We present a method for constructing numerical schemes with up to 3rd strong convergence order for solution of a class of stochastic differential equations, including equations of the Langevin type. The construction proceeds in two stages. In the first stage one approximates the stochastic equation by a differential equation with smooth coefficients randomly sampled at each time step. In the second stage the resulting regular equation is solved with the conventional operator-splitting techniques. This separation renders the approach flexible, allowing one to freely combine the numerical techniques most suitable to the problem at hand. The approach applies to ordinary and partial stochastic differential equations. In the latter case, it naturally gives rise to pseudo-spectral algorithms. We numerically test the strong convergence of several schemes obtained with this method in mechanical examples. Application to partial differential equations is illustrated by real-time simulations of a scalar field with quartic self-interaction coupled to a heat bath. The simulations accurately reproduce the thermodynamic properties of the field and are used to explore dynamics of thermal false vacuum decay in the case of negative quartic coupling.

We consider constraints on the axion-photon coupling by superradiance due to a plasma instability in the magnetospheres of millisecond pulsars. We compute the growth rate of a superradiant axion cloud in a dipole magnetic field, and give a semi-analytical formula for the superradiance rate for the lowest state. By requiring the associated instability time to be longer than the characteristic age of the supermassive black-widow millisecond pulsar PSR J0952-0607, we examine the pulsar-timing array constraints on axions of mass $\sim 10^{-12}\text{ eV}$. We find that competitive axion bounds from plasma instabilities are unlikely unless a new high spin pulsar is discovered.

We investigate the gravitational particle production from vacuum for a minimally coupled fermionic spectator field during a single-field inflationary phase. We observe that metric perturbations arising from the quantum fluctuations of a scalar inflaton field enhance gravitational production, showing that such a perturbative contribution becomes dominant if the field mass is sufficiently smaller than the inflationary Hubble rate. We focus on modes that leave the Hubble horizon during the latest stages of slow-roll and we numerically compute the total number of particles obtained from perturbations, providing a lower bound on the amount of such \enquote{geometric} particles for the case of Starobinsky inflation and a quadratic hilltop scenario. Our outcomes are compatible with the net observational cold dark matter abundance as experimentally measured, whose dark matter candidate exhibits mass in the range $10^5 \lesssim m \lesssim 10^7$ GeV, excluded by previous non-perturbative calculations.

Alfvénic turbulence is an effective mechanism for particle acceleration in strongly magnetized, relativistic plasma. In this study, we investigate a scenario where turbulent plasma is influenced by a strong guide magnetic field, resulting in highly anisotropic turbulent fluctuations. In such cases, the magnetic moments of particles are conserved, which means that acceleration can only occur along the direction of the magnetic field. Consistent with previous analytic studies, we find through PIC simulations of magnetically dominated pair plasma that the momenta of accelerated particles are closely aligned with the magnetic field lines. Notably, the alignment angle decreases as particle energy increases, potentially limited only by the inherent curvature and gradients of the turbulent magnetic fluctuations. This finding has significant implications for interpreting the synchrotron radiation emitted by highly accelerated particles.

Recent advances, including gravitational wave detections and imaging of black hole shadows, have strongly validated general relativity. Nevertheless, ongoing cosmological observations suggest potential limitations of general relativity, spurring interest in modified theories of gravity. This study explores Lorentz gauge theory, an alternative gravitational framework offering promising solutions to longstanding conceptual issues in quantum gravity and cosmology. By analyzing black hole shadow structures and gravitational lensing effects-both weak and strong deflection regimes-we highlight unique observational signatures of Lorentz gauge gravity. Our findings provide valuable tools for future observational tests, potentially distinguishing these modified gravity models from general relativity and advancing our understanding of spacetime geometry and fundamental gravitational interactions.

We present a novel concept of enhanced asymmetric dark matter annihilation in astrophysical bodies like the Sun in the presence of multiple dark matter candidates based on hidden annihilation mechanisms. We consider hidden sector annihilation of a heavy dark matter into an asymmetric dark matter, resulting in a significant change in the dark matter annihilation flux and the muon flux at neutrino detectors. We quantify expected changes in the muon flux with scaling parameters for the symmetric or asymmetric nature of the heavier dark matter candidate.

The conceptual problems of the standard slow-roll inflationary scenario include the Trans-Planckian Censorship Conjecture issue, which severely restricts the tensor-to-scalar ratio in the standard minimally coupled scalar field inflation. Motivated by the fact that a scalar field in its vacuum configuration can be minimally coupled to gravity, or conformally coupled, and also that the first quantum corrections of the scalar field action include $R^2$ corrections, in this work we assume that $R^2$ gravity in the presence of a scalar field with constant equation of state parameter co-exist and control the early Universe. Constant equation of state parameter scalar field result from exponential scalar potentials. In our approach, the standard slow-roll era is controlled by the $R^2$ gravity and is followed by a power-law inflationary tail governed by a minimally coupled scalar field with an quintessential equation of state parameter, stemming from an exponential scalar potential. The fact that the total equation of state parameter after the end of the slow-roll era is equal to the value determined by the scalar field, has an effect on the duration of the $R^2$ governed slow-roll era, and it actually shortens the duration of the slow-roll era, by an extent which depends on the reheating temperature too, after all the inflationary patches have ended. The power-law inflationary tail to the standard $R^2$ inflation, solves the Trans-Planckian Censorship Conjecture issues, and also the Swampland conjecture can be amended in this context. We also perform a dynamical system study to confirm numerically our findings.

The effective field theory (EFT) of dark energy provides a unified model independent theoretical framework to study the effects of dark energy and modified gravity. We show that the EFT allows to derive a theory independent consistency relation between the effective gravitational constant, the gravitational and electromagnetic luminosity distance and the speed of gravitational waves (GW), which generalizes the results obtained in some luminal modified gravity theories. We apply the consistency relation to map the large scale structure observational constraints on the effective gravitational constant to GW-EMW distance ratio constraints. The consistency relation allows to probe the value of the effective gravitational constant with multimessenger observations, independently from large scale structure observations, or at high redshift, where only GW events and their electromagnetic counterpart are observable.

A system of exclusive fermions occurs when two fermions of opposite spin are prohibited from occupying the same quantum level. We derive the distribution of exclusive fermions via the employment of the grand canonical ensemble. Salient features of its statistical properties, compared to the free electron gases, include: larger Fermi energy, higher degeneracy pressure, but the same Pauli paramagnetism and Landau diamagnetism. In particular, higher degeneracy pressure leads to an inflation of the Chandrasekhar limit to 1.6 times when applied to white dwarf stars and neutron stars.

We review the gauged quintessence scenario, wherein the quintessence scalar field responsible for dark energy is promoted to a complex field charged under a dark $U(1)$ gauge symmetry. This construction leads to new and potentially rich cosmological phenomenology. After a concise recap of the standard quintessence scenario, we highlight how a $U(1)$ gauge invariance alters the dynamics of the scalar and the associated dark gauge boson. We survey the evolution of both fields across cosmic history, discuss their possible production via a misalignment mechanism, and examine implications for the Hubble tension. We also comment on potential non-gravitational signals of gauged quintessence through kinetic mixing (the dark photon vector portal).

We study the properties of supercritical Reissner-Nordström Anti-de Sitter (RN-AdS) black holes in the extended phase space with the pressure defines as the cosmological constant. Supercritical black holes exist in the region where both temperature and pressure exceed the critical point, known as the supercritical region. The conventional view states that black holes in this regime are indistinguishable between large and small phases. However, recent research reveals that the supercritical regime exhibits universal gas-like and liquid-like phase separation, which shed light on the study on the supercritical region of RN-AdS black holes in the extended phase space. In this work, we calculate the thermodynamic potential and quasinormal modes (QNMs) of RN-AdS black holes, and identify transition curves between two different states in supercritical region using thermodynamic and dynamic methods. On one hand, we find the thermodynamic crossover curve (Widom line) by defining the scaled variance $\Omega$ (a higher-order derivative of Gibbs free energy). On the other hand, we identify the dynamic crossover curve (Frenkel line) by analyzing transitions between distinct QNM decay modes.

Exoplanets play an important role in understanding the mechanics of planetary system formation and orbital evolution. In this context the correlations of different parameters of the planets and their host star are useful guides in the search for explanatory mechanisms. Based on a reanalysis of the data set from \cite{figueria14} we study the as of now still poorly understood correlation between planetary surface gravity and stellar activity of Hot Jupiters. Unfortunately, data collection often suffers from measurement errors due to complicated and indirect measurement setups, rendering standard inference techniques unreliable. We present new methods to estimate and test for correlations in a deconvolution framework and thereby improve the state of the art analysis of the data in two directions. First, we are now able to account for additive measurement errors which facilitates reliable inference. Second we test for relevant changes, i.e. we are testing for correlations exceeding a certain threshold $\Delta$. This reflects the fact that small nonzero correlations are to be expected for real life data almost always and that standard statistical tests will therefore always reject the null of no correlation given sufficient data. Our theory focuses on quantities that can be estimated by U-Statistics which contain a variety of correlation measures. We propose a bootstrap test and establish its theoretical validity. As a by product we also obtain confidence intervals. Applying our methods to the Hot Jupiter data set from \cite{figueria14}, we observe that taking into account the measurement errors yields smaller point estimates and the null of no relevant correlation is rejected only for very small $\Delta$. This demonstrates the importance of considering the impact of measurement errors to avoid misleading conclusions from the resulting statistical analysis.

In this paper we study quasinormal modes and absorption cross sections for the $(1+3)$-dimensional Bardeen black hole surrounded by perfect fluid dark matter. Studies of the massless scalar field is already done in \cite{Sun:2023slzl}. Hence, in this paper we will focus on the massive scalar field perturbations and massless Dirac field perturbations. To compute the quasinormal modes we use the semi-analytical 3rd-order WKB method, which has been shown to be one of the best approaches when the effective potential is adequate and when $n < \ell$ and $n < \lambda$. We have also utilized the Pöschl-Teller method to compare the valus obtained using the WKB approach. We have computed quasinormal frequencies by varying various parameters of the theory such as the mass of the scalar field $\mu$, dark matter parameter $\alpha$ and the magnetic charge $g$. We have summarized our solutions in tables and figures for clarity. As for the absorption cross section, we used third order WKB approach to compute reflection, transmission coefficients and partial absorption cross sections. Graphs are presented to demonstrate the behavior of the above quantities when the dark matter parameter and mass of the massive scalar field are varied.

Systematic R-matrix calculations of electron-impact excitation for ions of astrophysical interest have been performed since 2007 for many iso-electronic sequences as part of the UK Atomic Process for Astrophysical Plasma (APAP) network. Rate coefficients for Maxwellian electron distributions have been provided and used extensively in the literature and many databases for astrophysics. Here, we provide averaged collision strengths to be used to model plasma where electrons are non-Maxwellian, which often occur in laboratory and astrophysical plasma. We also provide for many ions new Maxwellian-averaged collision strengths which include important corrections to the published values. The H- and He-like atomic data were recently made available in Mao+(2022). Here, we provide data for ions of the Li-, Be-, B-, C-, N-, O-, Ne-, Na-, and Mg-like sequences.