Papers for Monday, Dec 02 2024

Neutron stars provide a compelling testing ground for gravity, nuclear dynamics, and physics beyond the Standard Model, and so it will be useful to locate the neutron stars nearest to Earth. To that end, we revisit pulsar distance estimates extracted from the dispersion measure of pulsar radio waves scattering on electrons. In particular, we create a new electron density map for the local kiloparsec by fitting to parallax measurements of the nearest pulsars, which complements existing maps that are fit on the Galactic scale. This ``near-Earth'' electron density map implies that pulsars previously estimated to be 100-200 pc away may be as close as tens of parsecs away, which motivates a parallax-based measurement campaign to follow-up on these very-near candidate pulsars. Such nearby neutron stars would be valuable laboratories for testing fundamental physics phenomena, including several late-stage neutron star heating mechanisms, using current and forthcoming telescopes. We illustrate this by estimating the sensitivities of the upcoming Extremely Large Telescope and Thirty Meter Telescope to neutron stars heated by dark matter capture.

Metal-poor stars enriched by a single supernova (mono-enriched stars) are direct proof (and provide valuable probes) of supernova nucleosynthesis. Photometric and spectroscopic observations have shown that metal-poor stars have a wide variety of chemical compositions; the star's chemical composition reflects the nucleosynthesis process(es) that occurred before the star's formation. While the identification of mono-enriched stars enables us to study the ejecta properties of a single supernova, the fraction of mono-enriched stars among metal-poor stars remains unknown. Here we identify mono-enriched stars in a star-by-star cosmological zoom-in simulation of a dwarf galaxy. We find that the fraction of mono-enriched stars is higher for lower metallicity, stars with [Fe/H] $< -2.5$. The percentages of mono-enriched stars are 11% at [Fe/H] = $-$5.0 and 1% at [Fe/H] = $-$2.5, suggesting that most metal-poor stars are affected by multiple supernovae. We also find that mono-enriched stars tend to be located near the center of the simulated dwarf. Such regions will be explored in detail in upcoming surveys such as the Prime Focus Spectrograph (PFS) on the Subaru telescope.

The differentiation between chaotic and stochastic systems has long been scrutinized, particularly in observations where data is often noise-contaminated and finite. Our research examines the dual nature of the black hole X-ray binary IGR J17091-3624, an object whose behavior has been closely studied in parallel to GRS 1915+105. Remarkable similarities in the temporal classes of these two objects are explored in literature. However, this was not the case with their non-linear dynamics: GRS 1915+105 shows signs of determinism, while IGR J17091-3624 was found to be stochastic. In this study, we confront the inherent challenge of noise contamination, as in IGR J17091-3624, faced by previous studies, particularly Poisson noise, which adversely impacts the reliability of non-linear results. We employ several denoising techniques to mitigate noise effects and employ methods like Autoencoder, Principal Component Analysis (PCA), Singular Value Decomposition (SVD), and Correlation Integral (CI) to isolate the deterministic signatures. We have found signs of determinism in IGR J17091-3624 after denoising, thus supporting the hypothesis of it being similar to GRS 1915+105, even as a dynamical system.

Recent structure models of Jupiter suggest the existence of an extended region in the deep interior with a high heavy element abundance, referred to as a dilute core. This finding has led to increased interest in modelling the formation and evolution processes with the goal of understanding how and under what circumstances such a structure is formed and retained, to in turn better understand the relation between atmospheric and bulk metallicity. We modelled the evolution of giant planets, varying various parameters relevant for the convective mixing process, such as the mixing length parameter and the size of the mesh, and parameters related to the general evolution, such as the orbital distance and the initial luminosity. We in particular studied hot Jupiters and find that the effect of bloating on the mixing process is small but can in some cases inhibit convective mixing by lowering the intrinsic luminosity for a given entropy. Semi-convection can significantly lower the extent of a dilute core if it is strong enough. We find that dilute cores are unable to persist for initial luminosities much higher than 3 x 1e3 LJ for a Jupiter-like planet for the initial heavy element profiles we studied. From this we conclude that, based on our model, it is unlikely that a large number of giant planets retain a dilute core throughout their evolution, although this is dependent on the assumptions and limitations of our method. Future work should focus on improving the link between formation and evolution models so that the mixing process is accurately modelled throughout a planet's lifetime and on improving the understanding of how to model convection near radiative-convective boundaries.

Over the last few decades, there has been considerable interest in the violation of the sacred "Chandrasekhar" mass limit of white dwarfs (WDs). Peculiar over-luminous type Ia supernovae (such as SNLS-03D3bb) lend observational support to the idea that these super-Chandrasekhar WDs exist. Our group, for more than a decade, has been actively working on the theoretical possibility of these objects through the presence of the star's magnetic field. The magnetic field greatly contributes to the existence of these massive WDs, both through classical and quantum effects. In this work, we explore super-Chandrasekhar WDs, formed via evolution from a main sequence star, as a result of the classical effects of the star's magnetic field. We obtain super-Chandrasekhar WDs and new mass limit(s), depending on the magnetic field geometry. We explore the full evolution and stability of these objects from the main sequence stage through the one-dimensional stellar evolution code STARS. In order to do so, we have appropriately modified the given codes by introducing magnetic effect and cooling. Our simulation confirms that massive WDs are possible in the presence of a magnetic field satisfying underlying stability.

In the past, researchers have mostly relied on single-resolution images from individual telescopes to detect gravitational lenses. We propose a search for galaxy-scale lenses that, for the first time, combines high-resolution single-band images (in our case the Hubble Space Telescope, HST) with lower-resolution multi-band images (in our case Legacy survey, LS) using machine learning. This methodology aims to simulate the operational strategies that will be employed by future missions, such as combining the images of Euclid and the Rubin Observatory's Legacy Survey of Space and Time (LSST). To compensate for the scarcity of lensed galaxy images for network training, we have generated mock lenses by superimposing arc features onto HST images, saved the lens parameters, and replicated the lens system in the LS images. We test four architectures based on ResNet-18: (1) using single-band HST images, (2) using three bands of LS images, (3) stacking these images after interpolating the LS images to HST pixel scale for simultaneous processing, and (4) merging a ResNet branch of HST with a ResNet branch of LS before the fully connected layer. We compare these architecture performances by creating Receiver Operating Characteristic (ROC) curves for each model and comparing their output scores. At a false-positive rate of $10^{-4}$, the true-positive rate is $\sim$0.41, $\sim$0.45, $\sim$0.51 and $\sim$0.55, for HST, LS, stacked images and merged branches, respectively. Our results demonstrate that models integrating images from both the HST and LS significantly enhance the detection of galaxy-scale lenses compared to models relying on data from a single instrument. These results show the potential benefits of using both Euclid and LSST images, as wide-field imaging surveys are expected to discover approximately 100,000 lenses.

Maps of the magnetic field at the Sun's surface are commonly used as boundary conditions in space-weather modeling. However, continuous observations are only available from the Sun's Earth-facing side. One commonly used approach to mitigate the lack of far-side information is to apply a surface flux transport (SFT) model to model the evolution of the magnetic field as the Sun rotates. Helioseismology can image active regions on the far side using acoustic oscillations, and hence has the potential to improve the modeled surface magnetic field. In this study, we propose a novel approach for estimating magnetic fields of active regions on the Sun's far side based on seismic measurements, and then include them into a SFT model. To calibrate seismic signal to magnetic field, we apply our SFT model to line-of-sight magnetograms from SDO/HMI to obtain reference maps of global magnetic fields. The resulting maps are compared with seismic maps on the Sun's far side computed using helioseismic holography. The spatial structure of the magnetic field within an active region is reflected in the spatial structure of seismic phase shifts. We assign polarities to the unipolar magnetic-field concentrations based on Hale's law and require approximate flux balance between the two polarities. From 2010 to 2024, we modeled 859 active regions, with an average total unsigned flux of $7.84\cdot 10^{21}$ Mx and an average area of $4.48\cdot 10^{10}$ km$^{2}$. Approximately $4.2\%$ of the active regions were found to have an anti-Hale configuration, which we manually corrected. Comparisons between modeled open-field areas and EUV observations reveal a substantial improvement in agreement when far-side active regions are included. This proof of concept study demonstrates the potential of the ``combined surface flux transport and helioseismic Far-side Active Region Model'' (FARM) to improve space-weather modeling.

This study uses the Pearson's chi-square test to analyze the VNIR reflectance spectra of seven asteroids and look for spectral matches among approximately 11,000 laboratory spectra of meteoritic, terrestrial, synthetic, Apollo, and Luna samples. First, we use the chi-square method to analyze three well-studied asteroids - (4) Vesta, (6) Hebe, and (19) Fortuna - to establish the technique's reliability by attempting to confirm previously predicted spectral matches. The chi-square test is then applied to four other asteroids: the Mars trojans (5261) Eureka, (101429) 1998 VF31, (311999) 2007 NS2, and (385250) 2001 DH47. This study focuses on Mars trojans because of their undetermined origin and possible relationship to Mars. For asteroids that may have undergone space weathering, reddening effects are removed from the spectra to allow for a more accurate chi-square analysis. The top chi-square matches among the Mars trojans reveal significant spectral similarities with Martian meteorites and minerals found on Mars, supporting the hypothesis of a Martian origin for the analyzed Mars trojans. However, the possibility that these Mars trojans could be fragments of a disrupted differentiated body or bodies cannot be ruled out. We find that using the chi-square test with a large number of laboratory spectra is a very useful initial technique for identifying spectral analogs to asteroids.

Dark matter (DM) models with a non-zero DM-baryon interaction cross section imply energy transfer between DM and baryons. We present a new method of constraining the DM-baryon interaction cross section and DM particle mass for velocity-independent interactions using the thermodynamics of galaxy clusters. If the baryonic gas in these clusters is in thermodynamic equilibrium and DM cools baryons, this cooling rate is limited by the net heating rate of other mechanisms in the cluster. We use the REFLEX clusters from the Meta-Catalogue of X-ray detected Clusters of Galaxies (MCXC) with mass estimates from the Atacama Cosmology Telescope (ACT) catalog of Sunyaev-Zel'dovich (SZ) selected galaxy clusters. This yields 95% upper bounds on the DM-proton interaction cross section for velocity-independent interactions of $\sigma_0\leq9.3\times10^{-28} \mathrm{~cm^2}$ for DM masses, $m_\chi = 10^{-4} - 10^{-1}$ GeV. These constraints are within an order of magnitude of the best constraints derived in this mass range, and serve as a complementary, independent constraint. We also apply this model to the fractional interacting DM scenario, where only 10% and 1% of the DM is interacting. Unlike other methods, this constraint scales linearly with this fraction. This yields 95% upper bounds of $\sigma_0\leq1.1\times10^{-26} \mathrm{~cm^2}$ and $\sigma_0\leq8.2\times10^{-26} \mathrm{~cm^2}$, which are the strongest existing constraints for this scenario. This paper serves as a proof of concept. Upcoming SZ measurements will provide temperature profiles for galaxy clusters. Combining these measurements with more complex thermodynamic models could lead to more robust constraints.

We report on follow-up observations of the recently discovered transient by the Einstein Probe, EP240709A, with the Neutron star Interior Composition Explorer (NICER). We also incorporated archival multiwavelength survey data from the Neil Gehrels Swift Observatory (X-ray), Gaia (optical), the Fermi Gamma-ray Space Telescope (gamma-ray), and the Wide-field Infrared Survey Explorer (infrared) to distinguish between blazars and stellar systems. We suggest that EP240709A is likely an active blazar.

The abundance of dark matter haloes as a function of halo mass is a key diagnostic for constraining the cosmological model. The theoretical framework based on excursion set arguments, when applied to an initial Gaussian random field of density fluctuations, predicts universal behaviour for this quantity, when variables are recast in terms of peak height. The great advantage of this, if true, is that it implies one simply needs to accurately simulate only a single cosmological model to build an emulator for any other cosmology of interest. This tantalising possibility has inspired a number of studies over the years. In practice, the diversity of ways for defining haloes has led to a variety of mixed results concerning this issue. In this work, we utilise a suite of high-resolution cosmological $N$-body simulations, to revisit this question for friends-of-friends haloes. We perform our study in the context of the flat, time-evolving dark energy model (hereafter $w$CDM), and with simple modifications of the primordial physics afforded through variations of the scalar power spectral index and its possible running. We construct the universal mass function locus from our fiducial simulation (a ${\Lambda}$CDM model) and emulate this using a linear interpolating function. We then compare this against the loci that we measure for our array of alternate models. We find mass functions that are consistent with universality to within ${\lesssim} \ 5\%$ in the fractional difference, with respect to variations of the 8 cosmological parameters that we have considered (2 variations per parameter) and for redshifts $z < 7$.

Spectrum analysis at 3 mm of the central region ($r\sim$800 pc) of NGC\,4303 showed molecular gas lines of both dense gas tracers (HCN, HNC, HCO$^+$, and C$_2$H) and diffuse gases ($^{13}$CO and C$^{18}$O). Molecular gas derived parameters: $H_2$ mass $M_{H_2}$=(1.75$\pm$0.32)$\times10^{8}$ M$_{\odot}$; radial velocity, V$_{dense}=$178$\pm$60 km\,s$^{-1}$, and V$_{CO}=$151$\pm$29 km\,s$^{-1}$; HCN luminosity $L_{HCN}$=(7.38$\pm$1.40)$\times10^{6}\,\,K\,\,km\,\,s^{-1}\,pc^{2}$; dense gas mass $M_{dense}$=(4.7$\pm$0.3) $\times 10^{7}$ M$_{\odot}$, and dense gas tracers abundances indicating that dense gas contributes significantly to the total molecular gas mass. To explore the AGN nature and central dusty torus of the galaxy, CIGALE was used to fit the integrated spectral energy distribution from submillimeter to UV frequencies. Large torus properties are estimated: luminosity $L_{TORUS}$\,=\,(7.1$\pm$2.8) $\times 10^{43}$ erg s$^{-1}$ and line of sight inclination of 67$\pm$16$^\circ$, which is consistent with a Type 2 AGN; total infrared luminosity $L_{IR}$=(3.51$\,\pm$\,0.30)$\times 10^{44}$ erg s$^{-1}$; star formation rate $SFR$=6.0$\pm$0.3 M$_{\odot}$\,yr$^{-1}$; and found that the AGN contribution is marginal at $\sim$20\%.

Quiet-Sun regions cover most of the Sun's surface; its magnetic fields contribute significantly to the solar chromospheric and coronal heating. However, characterizing the magnetic fields of the quiet Sun is challenging due to their weak polarization signal. The 4-m \textit{Daniel K. Inouye Solar Telescope} (\textit{DKIST}) is expected to improve our understanding of the quiet-Sun magnetism. In this paper, we assess the diagnostic capability of the Diffraction-Limited Near Infrared Spectropolarimeter (DL-NIRSP) instrument on \textit{DKIST} on the energy transport processes in the quiet-Sun photosphere. To this end, we synthesize high-resolution, high-cadence Stokes profiles of the \ion{Fe}{1} 630~nm lines using a realistic magnetohydrodynamic simulation, degrade them to emulate the \textit{DKIST}/DL-NIRSP observations, and subsequently infer the vector magnetic and velocity fields. For the assessment, we first verify that a widely used flow-tracking algorithm, Differential Affine Velocity Estimator for Vector Magnetograms, works well for estimating the large-scale ($> 200$ km) photospheric velocity fields with these high-resolution data. We then examine how the accuracy of inferred velocity depends on the temporal resolution. Finally, we investigate the reliability of the Poynting flux estimate and its dependence on the model assumptions. The results suggest that the unsigned Poynting flux, estimated with existing schemes, can account for about $71.4\%$ and $52.6\%$ of the reference ground truth at $\log \tau =0.0$ and $\log \tau = -1$. However, the net Poynting flux tends to be significantly underestimated. The error mainly arises from the underestimated contribution of the horizontal motion. We discuss the implications on \textit{DKIST} observations.

We present a 19.7 - 214 $\mu$m imaging atlas of local (4 - 181 Mpc; median 43 Mpc) active galactic nuclei (AGN) observed with FORCAST and HAWC+ on board the SOFIA telescope with angular resolutions ~ 3"- 20". This atlas comprises 22 Seyferts (17 Type 2 and 5 Type 1) with a total of 69 images, 41 of which have not been previously published. The AGN span a range of luminosities of log$_{10}$ ($L_{bol}$ [erg/s]) = [42, 46] with a median of log$_{10}$ ($L_{bol}$ [erg/s]) = 44.1 $\pm$ 1.0. We provide total fluxes of our sample using aperture photometry for point source objects and a 2-D Gaussian fitting for objects with extended host galaxy emission, which was used to estimate the unresolved nuclear component. Most galaxies in our sample are point-like sources, however, four sources (Centaurus A, Circinus, NGC 1068, and NGC 4388) show extended emission in all wavelengths. The 30 - 40 $\mu$m extended emission in NGC 4388 is coincident with the narrow line region at PA ~ 50$^{\circ}$, while the dusty extension at longer wavelengths arises from the host galaxy at PA ~ 90$^{\circ}$. Our new observations allow us to construct the best sampled spectral energy distributions (SEDs) available between 30 - 500 $\mu$m for a sample of nearby AGN. We estimate that the average peak wavelength of the nuclear SEDs is ~ 40 $\mu$m in $\nu$F$_{\nu}$ , which we associate with an unresolved extended dusty region heated by the AGN.

Context. Spectroscopic surveys like APOGEE, GALAH, and LAMOST have significantly advanced our understanding of the Milky Way by providing extensive stellar parameters and chemical abundances. Complementing these, photometric surveys with narrow/medium-band filters, such as the Southern Photometric Local Universe Survey (S-PLUS), offer the potential to estimate stellar parameters and abundances for a much larger number of stars. Aims. This work develops methodologies to extract stellar atmospheric parameters and selected chemical abundances from S-PLUS photometric data, which spans ~3000 square degrees using seven narrowband and five broadband filters. Methods. Using 66 S-PLUS colors, we estimated parameters based on training samples from LAMOST, APOGEE, and GALAH, applying Cost-Sensitive Neural Networks (NN) and Random Forests (RF). We tested for spurious correlations by including abundances not covered by the S-PLUS filters and evaluated NN and RF performance, with NN consistently outperforming RF. Including Teff and log g as features improved accuracy by ~3%. We retained only parameters with a goodness-of-fit above 50%. Results. Our approach provides reliable estimates of fundamental parameters (Teff, log g, [Fe/H]) and abundance ratios such as [{\alpha}/Fe], [Al/Fe], [C/Fe], [Li/Fe], and [Mg/Fe] for ~5 million stars, with goodness-of-fit >60%. Additional ratios like [Cu/Fe], [O/Fe], and [Si/Fe] were derived but are less accurate. Validation using star clusters, TESS, and J-PLUS data confirmed the robustness of our methodology. Conclusions. By leveraging S-PLUS photometry and machine learning, we present a cost-effective alternative to high-resolution spectroscopy for deriving stellar parameters and abundances, enabling insights into Milky Way stellar populations and supporting future classification efforts.

We present the polarization calibration of the 19-beam receiver at 1420 MHz within the full illumination of the Five-hundred-meter Aperture Spherical Telescope from October 2018 to March 2023. We perform spider observations to characterize the on-axis Mueller matrix of the central beam. The calibrated polarization percentage and polarization angle of a source with strong linear polarization emission are about 0.2\% and 0.5$^{\circ}$. Several parameters of the central-beam Mueller matrix show time variability from months to years, suggesting relatively frequent polarization calibrations are needed. We obtain the Mueller matrix parameters of the 18 off-center beams with the combination of on-the-fly observations and spider observations. The polarization calibration provides consistent fractional Stokes parameters of the 19 beams, although the Mueller matrix parameters of the off-center beams are not as accurate as those of the central beam. The Mueller matrix parameters of the central beam do not show a strong dependence on the reflector surface. However, we notice different off-center Mueller matrix parameters between the eastern and western sides of the reflector surface. We provide average parameters of the 19-beam Mueller matrices which should be applicable to observations from 2020 to 2022 with several caveats. After applying the average parameters, on-axis fractional linear polarization measurements $\gtrsim$ 10\% and on-axis fractional circular polarization measurements $\gtrsim$ 1.5\% can be considered high-confidence detections. For sources with weak polarization, timely polarization calibrations using spider observations are required.

Photometric redshifts will be a key data product for the Rubin Observatory Legacy Survey of Space and Time (LSST) as well as for future ground and space-based surveys. The need for photometric redshifts, or photo-zs, arises from sparse spectroscopic coverage of observed galaxies. LSST is expected to observe billions of objects, making it crucial to have a photo-z estimator that is accurate and efficient. To that end, we present DeepDISC photo-z, a photo-z estimator that is an extension of the DeepDISC framework. The base DeepDISC network simultaneously detects, segments, and classifies objects in multi-band coadded images. We introduce photo-z capabilities to DeepDISC by adding a redshift estimation Region of Interest head, which produces a photo-z probability distribution function for each detected object. On simulated LSST images, DeepDISC photo-z outperforms traditional catalog-based estimators, in both point estimate and probabilistic metrics. We validate DeepDISC by examining dependencies on systematics including galactic extinction, blending and PSF effects. We also examine the impact of the data quality and the size of the training set and model. We find that the biggest factor in DeepDISC photo-z quality is the signal-to-noise of the imaging data, and see a reduction in photo-z scatter approximately proportional to the image data signal-to-noise. Our code is fully public and integrated in the RAIL photo-z package for ease of use and comparison to other codes at this https URL

In this work, we aim to estimate the stellar parameters of the primary (Aa) by performing asteroseismic analysis on its period-spacing pattern. We use the C-3PO neural network to perform asteroseismic modelling of the g-mode period-spacing pattern of Aa, discussing the interplay of this information with external constraints from spectroscopy ($T_{\rm eff}$ and $\log(g)$) and eclipse modelling ($R$). To estimate the level of uncertainty due to different frequency extraction and pattern identification processes, we consider four different variations on the period-spacing patterns. To better understand the correlations between and the uncertainty structure of our parameter estimates, we also employed a classical, parameter-based MCMC grid search on four different stellar grids. The best-fitting, externally constrained model to the period-spacing pattern arrives at estimates of the stellar properties for Aa of: $M=1.51 \pm 0.05 M_\odot$, $X_c =0.43 \pm 0.04$, $R=1.66 \pm 0.1 R_\odot$, $f_{\rm ov}=0.010$, $\Omega_c=1.58 \pm 0.01$ d$^{-1}$ with rigid rotation to within the measurement errors, $\log(T_{\rm eff})=3.856 \pm 0.008$ dex, $\log(g)=4.18 \pm 0.04$ dex, and $\log(L)=0.809 \pm 0.005$ dex, which agree well with previous measurements from eclipse modelling, spectroscopy, and the Gaia DR3 luminosity. We find that the near-core properties of the best-fitting asteroseismic models are consistent with external constraints from eclipse modelling and spectroscopy. Aa appears to be a typical example of a $\gamma$ Dor star, fitting well within existing populations. We find that Aa is quasi-rigidly rotating to within the uncertainties, and note that the asteroseismic age estimate for Aa (1100 $\pm$ 100 Myr) is considerably older than the young (35 Myr) age implied by previous isochrone fits to the B binary in the literature. Our MCMC parameter-based grid-search agrees well with our pattern-modelling approach.

Infrared-faint radio sources (IFRSs) are believed to be a rare class of radio-loud active galactic nuclei (RL AGN) characterized by their high radio-to-infrared flux density ratios of up to several thousands. Previous studies have shown that a fraction of IFRSs are likely to be hosted in dust-obscured galaxies (DOGs). In this paper, our aim was to probe the dust properties, star formation rate (SFR), and AGN activity of IFRSs by modeling the UV-to-infrared spectral energy distribution (SED) of 20 IFRSs with spectroscopic redshifts ranging from 1.2 to 3.7. We compare the Bayesian evidence of a three-component model (stellar, AGN and cold dust) with that of a two-component model (stellar and cold dust) for six IFRSs in our sample with far-infrared (FIR) photometry and find that the three-component model has significantly higher Bayesian evidence, suggesting that IFRSs are most likely to be AGN. The median SED of our IFRS sample shows similarities to AGN-starburst composite in the IR regime. The derived IR luminosities of IFRSs indicate that they are low-luminosity counterparts of high-redshift radio galaxies. We disentangle the contributions of AGN-heated and star-formation-heated dust to the IR luminosity of IFRSs and find that our sample is likely AGN-dominated. However, despite the evidence for significant impact of AGN on the host galaxy, the AGN luminosity of our sample does not show correlation with the SFR of the sources.

The ejection of neutron-rich matter is one of the most important consequences of a neutron star merger. While the bulk of the matter is ejected at fast, but non-relativistic velocities ($\sim0.2c$), a small amount of mildly relativistic dynamic ejecta have been seen in a number of numerical simulations. Such ejecta can have far reaching observational consequences ranging from the shock breakout burst of gamma-rays promptly after the merger, to an early ($\sim 1$ hour post-merger) blue kilonova precursor signal, to synchrotron emission years after the merger ("kilonova afterglow"). These all potentially carry the imprint of the binary system parameters and the equation of state. By analyzing Lagrangian simulations in full General Relativity, performed with the code SPHINCS\_BSSN, we identify two ejection mechanisms for fast ejecta: i) about 30\% of the ejecta with {$v> 0.4c$} are "sprayed out" from the shear interface between the merging stars and escape along the orbital plane and ii) the remaining $\sim$ 70\% of the fast ejecta result from the central object "bouncing back" after strong, general-relativistic compression. This "bounce component" is ejected in a rather isotropic way and reaches larger velocities (by $\sim0.1c$) so that its faster parts can catch up with and shock slower parts of the spray ejecta. Even for a case that promptly collapses to a black hole, we find fast ejecta with similar properties to the non-collapsing case, while slower matter parts are swallowed by the forming black hole. We discuss observational implications of these fast ejecta, including shock breakout and kilonova afterglow.

We present SynthPop, a new open source, modular population synthesis Galactic modeling software to simulate catalogs of Milky Way stars along any sightline outward from the Sun. Motivated by a lack flexibility in existing Galactic models, SynthPop is coded entirely in python, can be run standalone or as an imported module, and is configured by json files that allow different model components to be switched out as desired. We describe the modular code structure, how the population generation process runs, and how to use the code. We also present model validation testing and known inaccuracies, and present an example of the code use, comparing Gaia data and the Gaia Universe Model Snapshot to a SynthPop implementation. The code is available now via GitHub with ReadTheDocs documentation and can be installed via pip.

Pulsating stars in eclipsing binaries are very important to understand stellar interior structures through astroseismology because their absolute parameters such as the masses and radii can be determined in high precision based on photometric and spectroscopic data. The high-precision and continuously time-series photometric data of the Transiting Exoplanet Survey Satellite (TESS) provides an unprecedented opportunity to search for and study this kind of variable stars in the whole sky. About 1626 Algol type (EA-type) eclipsing binary systems were observed by TESS in the 1-45 sectors with 2-minutes short cadence. By analyzing those TESS data, we found 57 new pulsating stars in EA-type binary stars. The preliminary results show that those binary systems have orbital periods in the range from 0.4 to 27 days, while the periods of pulsating components are in the range from 0.02 to 5 days. It is detected that 43 targets follow the correlation between pulsation and orbital periods of oscillating eclipsing binaries of Algol type (oEA), which may indicate that they are typical oEA stars. The other 14 targets may be other types of variable stars in eclipsing binary systems. These objects are a very interesting source to investigate the binary structures and evolutions as well as to understand the influences of tidal forces and mass transfer on stellar pulsations.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been fully operational since 11 January 2020. We present a comprehensive analysis of the beam structure for each of the 19 feed horns on FAST's L-band receiver across the Stokes I, Q, U, and V parameters. Using an on-the-fly mapping pattern, we conducted simultaneous sky mapping using all 19 beams directed towards polarization calibrators J1407+2827 and J0854+2006 from 2020 to 2022. Electromagnetic simulations were also performed to model the telescope's beam patterns in all Stokes parameters. Our findings reveal a symmetrical Gaussian pattern in the Stokes I parameter of the central beam without strong sidelobes, while the off-center beams exhibit significant asymmetrical shapes that can be fitted using a combination of log-normal and Gaussian distributions. The inner beams have higher relative beam efficiencies and smaller beam sizes compared to those of the outer beams. The sidelobes of the inner beams contribute approximately 2% of the total flux in the main lobe, increasing to 5% for outer beams, with a peak at 6.8%. In Stokes U, a distinct four-lobed cloverleaf beam squash structure is observed, with similar intensity levels in both inner and outer beams. In Stokes V, a two-lobed beam squint structure is observed in the central beam, along with a secondary eight-lobed structure. The highest squint peak in Stokes V is about 0.3% of the Stokes I in the outer beams. These results align closely with the simulations, providing valuable insights for the design of radio multi-beam observations.

The power spectrum of the primordial curvature perturbation $\mathcal{P}_\mathcal{R}$ has been measured with high precision on large scales $10^{-4}\lesssim k\lesssim 3~\rm Mpc^{-1}$, basing on the observations of cosmic microwave background, Lyman-$\alpha$ forest and large scale structure. On small scales $3\lesssim k \lesssim 10^{23}~\rm Mpc^{-1}$, the constrains are mainly from the studies on the primordial black holes (PBHs). Specifically, on small scales $10^{17}\lesssim k\lesssim 10^{23}~{\rm Mpc^{-1}}$, the limits arise from studies on the lightest supersymmetric particles produced by PBHs radiation and the stable Planck-mass relics after its evaporation. It has been demonstrated that the big bang nucleosynthesis can be used to constrain the initial fraction of PBHs with masses $10^{9}\lesssim M_{\rm PBH}\lesssim 10^{13}~{\rm g}$, corresponding to the scales $10^{16}\lesssim k\lesssim 10^{18}~{\rm Mpc^{-1}}$. Recently, on one hand, it is found that the evaporation of light PBHs ($M_{\rm PBH}\lesssim 10^{9}\rm g$) can modify the expansion rate of the Universe and the baryon-to-photon ratio, resulting in the influences on the primordial abundance of light nuclei. On the other hand, it has been proposed that the `memory burden' effect can slow down the mass loss rate of black hole (BH), leading to the existence of light PBHs by now. Based on the recent theoretical research process of BH and the limits on the (initial) mass fraction of light PBHs with masses $10^{4}\lesssim M_{\rm PBH}\lesssim 10^{10}~\rm g$, we derive new constraints on $\mathcal{P}_\mathcal{R}$ on small scales $1.5\times 10^{18}\lesssim k\lesssim 2.5\times 10^{21}~\rm Mpc^{-1}$, which are rarely studied in previous literature.

The paper proposes a new approach for approximating the lateral distribution functions (LDF) of Cherenkov light emitted by the electromagnetic component of extensive air showers (EAS) in the Earth's atmosphere. The information basis of the study is a series of simulations with the CORSIKA code. To approximate the LDF atmospheric Cherenkov light the probability density functions of one-dimensional fractional stable distributions were used. The results obtained in the work allow us to propose a fast modeling method for the CORSIKA code using a procedure similar to the Nishimura-Kamata-Greisen (NKG) for calculating the LDF of the EAS electromagnetic component.

Current and future searches for dark matter axions, based on their resonant conversion to photons in a magnetic field, span many orders of magnitude, from the very low mass GUT-scale axion to the very high mass post-inflation axion. The higher end of this range, 10 GHz and above is challenging for conventional microwave cavity-based experiments, owing to the steep drop-off in volume and thus conversion power with frequency. We present results on a first step towards a tunable microwave resonator that can be made suitably large and sufficiently high in frequency to begin probing the lower end of the post-inflation axion mass range. The design incorporates a tunable symmetric lattice and a photonic band gap structure that confines the TM$_{010}$ mode to which the axion couples, while suppressing all TE modes to which the axion does not.

Changing-look active galactic nuclei (CL-AGNs), characterized by emerging or disappearing of broad lines accompanied with extreme continuum flux variability, have drawn much attention for their potential of revealing physical processes underlying AGN evolution. We perform seven-season spectroscopic monitoring on Mrk~1018, one of the earliest identified CL-AGN. Around 2020, we detect a full-cycle changing-look transition of Mrk~1018 within one year, associated with a nucleus outburst, which likely arise from the disk instability in the transition region between the outer standard rotation-dominated disk and inner advection-dominated accretion flow. Over the past forty-five years, the accretion rate of Mrk~1018 changed 1000 times and the maximum Eddington ratio reached 0.02. By investigating the relation between broad-line properties and Eddington ratio ($L_{\rm bol}/L_{\rm Edd}$), we find strong evidence that the full-cycle type transition is regulated by accretion. There exists a turnover point in the Balmer decrement, which is observed for the first time. The broad Balmer lines change from a single peak in Type 1.0-1.2 to double peaks in Type 1.5-1.8 and the double-peak separation decreases with increasing accretion rate. We also find that the full width at half maximum (FWHM) of the broad Balmer lines obeys FWHM$\propto (L_{\rm bol}/L_{\rm Edd})^{-0.27}$, as expected for a virialized BLR. The velocity dispersion $\sigma_{\rm line}$ follows a similar trend in Type 1.5-1.8, but displays a sharp increases in Type 1.0-1.2, resulting in a dramatic drop of FWHM/$\sigma_{\rm line}$. These findings suggest that a virialized BLR together with accretion-dependent turbulent motions might be responsible for the diversity of BLR phenomena across AGN population.

With recent observations confirming exoplanets orbiting white dwarfs, there is growing interest in exploring and quantifying the habitability of temperate rocky planets around white dwarfs. In this work, the limits of the habitable zone of an Earth-like planet around a white dwarf are computed based on the incident stellar flux, and these limits are utilized to assess the duration of habitability at a given orbital distance. For a typical $0.6 M_\odot$ white dwarf an Earth-like planet at $\sim 0.012$ AU could remain in the temporally evolving habitable zone, maintaining conditions to support life, for nearly 7 Gyr. In addition, additional constraints on habitability are studied for the first time by imposing the requirement of receiving sufficient photon fluxes for UV-mediated prebiotic chemistry and photosynthesis. We demonstrate that these thresholds are comfortably exceeded by planets in the habitable zone. The prospects for detecting atmospheric biosignatures are also evaluated, and shown to require integration times on the order of one hour or less for ongoing space observations with JWST.

Photons emitted during the formation of primordial hydrogen and helium atoms over the Epoch of Recombination are expected to be preserved as additive distortions to the Cosmic Microwave Background (CMB) spectrum. The 'ripple' like spectral features from Cosmological Recombination Radiation (CRR) have never been detected, and are expected to be 9 orders of magnitude fainter than the CMB. Array of Precision Spectrometers for the Epoch of Recombination - APSERa - is an upcoming ground-based experiment to detect the CRR signal over 2-6 GHz. While astrophysical foregrounds may be theoretically separated from the CRR signal using their inherently different spectral characteristics, instrument generated systematics present a practical problem. We present a first ever study to detect the CRR lines in the presence of a non-ideal antenna adopting a toy model for antenna beam chromaticity. Using Euclidean distance and Pearson correlation coefficient as metrics to distinguish between CRR signal presence and absence in a simulation pipeline, we demonstrate that it is indeed possible to detect the signal using a chromatic antenna. Furthermore, we show that there are different tolerances to the antenna non-ideality based on the type of chromaticity, observing location, and LST. These can inform antenna and experiment design for a practical detection.

Atmospheric mass loss is thought to have strongly shaped the sample of close-in exoplanets. These atmospheres should be lost isotropically, leading to no net migration on the planetary orbit. However, strong stellar winds can funnel the escaping atmosphere into a tail trailing the planet. We derive a simple kinematic model of the gravitational interaction between the planet and this anisotropic wind, and derive expressions for the expected migration of the planet. Over the expected range of parameters, we find typical migrations of a few tenths to a few percent inward. We argue that this modest migration may be observable for planet pairs near mean motion resonances, which would provide an independent observational constraint on atmospheric mass loss models.

The solar wind is typically categorized as fast and slow based on the measured speed ($v_\mathrm{sw}$). The separation between these two regimes is often set between 400 and 600 km/s without a rigorous definition. Observations of the solar wind's kinetic signatures, chemical makeup, charge state properties, and Alfvénicity suggest that such a two-state model may be insufficiently nuanced to capture the relationship between the solar wind and its solar sources. We test this two-state fast/slow solar wind paradigm with heavy ion abundances (X/H) and characterize how the transition between fast and slow wind states impacts heavy ion in the solar wind. We show that (1) the speed at which heavy ion abundances indicate a change between fast and slow solar wind as a function of speed is slower than the speed indicated by the helium abundance; (2) this speed is independent of heavy ion mass and charge state; (3) the abundance at which heavy ions indicate the transition between fast and slow wind is consistent with prior observations of fast wind abundances; (4) and there may be a mass or charge-state dependent fractionation process present in fast wind heavy ion abundances. We infer that (1) identifying slow solar wind as having a speed $v_\mathrm{sw} \lesssim$ 400 km/s may mix solar wind from polar and equatorial sources; (2) He may be impacted by the acceleration necessary for the solar wind to reach the asymptotic fast, non-transient values observed at 1 AU; and (3) heavy ions are fractionated in the fast wind by a yet-to-be-determined mechanism.

The radiation reprocessing model, in which an optically-thick outflow absorbs the high-energy emission from a central source and re-emits in longer wavelengths, has been frequently invoked to explain some optically bright transients, such as fast blue optical transients (FBOTs) whose progenitor and explosion mechanism are still unknown. Previous studies on this model did not take into account the frequency dependence of the opacity. We study the radiative reprocessing and calculate the UV-optical-NIR band spectra from a spherical outflow composed of pure hydrogen gas, for a time-dependent outflowing mass rate. Electron scattering and frequency-dependent bound-free, free-free opacities are considered. The spectrum deviates from the blackbody at NIR and UV frequencies; in particular, it has $\nu L_{\nu} \propto \nu^{1.5}$ at NIR frequencies, because at these frequencies the absorption optical depth from the outflow's outer edge to the so-called photon trapping radius is large and is frequency dependent. We apply our model to the proto-type FBOT AT2018cow by {the spectra} to the observed SED. The best-fit mass loss rate suggests that the total outflow mass in AT2018cow is $M_{\rm out} \approx 5.7^{+0.4}_{-0.4} \, M_{\odot}$. If that equals the total mass lost during an explosion, and if the progenitor is a blue supergiant (with a pre-explosion mass of $\sim 20 \, M_{\odot}$), then it will suggest that the central compact remnant mass is at least $\approx \, \rm{14 \, M_{\odot}}$. This would imply that the central remnant is a black hole.

The Gamma-Ray Transient Monitor (GTM) is an all-sky monitor onboard the Distant Retrograde Orbit-A (DRO-A) satellite, with the scientific objective of detecting gamma-ray bursts in the energy range of 20 keV to 1 MeV. The GTM is equipped with five Gamma-Ray Transient Probes (GTPs), utilizing silicon photomultiplier (SiPM) arrays coupled with NaI(Tl) scintillators for signal readout. To test the performance of the GTP in detecting electrons, we independently developed a continuous-energy-tunable, low-current, quasi-single-electron accelerator, and used this facility for ground-based electron calibration of the GTP. This paper provides a detailed description of the operational principles of the unique electron accelerator and comprehensively presents the process and results of electron calibration for the GTP. The calibration results indicate that the dead time for normal signals is less than 4 $\mu$s, while for overflow signals, it is approximately 70 $\mu$s, consistent with the design specifications. The GTP's time-recording capability is working correctly, accurately recording overflow events. The GTP responds normally to electrons in the 0.4-1.4 MeV energy range. The ground-based electron calibration validates the design of the GTP and enhances the probe's mass model, laying the foundation for payload development, in-orbit observation strategies, and scientific data analysis.

We analyse and model rapid rotations of polarization orientations in PSR B1919+21's single pulses, based on FAST observation data. In more than one third of B1919+21's single pulses, polarization angle (PA) is found to rotate quasi-monotonically with pulse longitude, by over 180 or even 360 degrees. Most of these quasi-monotonic PA curves have negative slopes with respect to pulse longitude. Oscillations of circular polarization fraction accompany these PA rotations. This rapid rotation could be induced by quick change of phase lag between normal wave modes within an individual pulse. We propose a phenomenological model to successfully reproduce the observed polarization rotations in single pulses, and calculate phase lags in a dipolar magnetic field of an aligned rotating pulsar, with a dispersion relation of orthogonal wave modes in strongly magnetized plasma. The weak frequency dependence of observed polarization rotation requires the radio emission height to be low, approximately 10 times the neutron star radius.

High-$z$ radio galaxies (HzRGs) are considered important objects for understanding the formation and evolution of massive galaxies in the early universe. However, till date, detailed studies of the stellar population of HzRGs such as the star-formation history have been scarce. Therefore, this study conducted a new survey to establish a less-biased sample of HzRGs and consequently investigate their properties. We utilized a sample of $g$-dropout Lyman break galaxies (LBGs) obtained from an optical wide and deep imaging survey made by Subaru Hyper Suprime-Cam (HSC). Based on the cross-matching of this LBG sample with the VLA FIRST radio survey data, we constructed a photometric sample of high-redshift radio galaxies (HzRGs) at $z \sim 4$ for $\sim$560 deg$^2$ survey field. Consequently, we identified 146 HzRG candidates. To analyze the characteristics of these candidates, we focus on objects exhibiting the near-infrared photometry of VIKING or UKIDSS and the mid-infrared photometry of unWISE (28 objects). The results indicate that 7 objects exhibit SEDs consistent with galaxies at $z \sim 4$. The HzRG candidates have very large stellar masses with $\sim 4.2 \times 10^{11} M_{\odot}$ on average. This stellar mass is similar to that of previously discovered USS HzRGs at $z \sim 4$, though our sample is affected by a sample selection bias that selects only HzRGs with $M_{\star} > 10^{11} M_{\odot}$. Further, the SEDs of those HzRG candidates suggest a past fast quenching with a rough timescale of $\sim$0.1 Gyr, as evidenced from the rest-frame UVJ diagram.

Our understanding of the intensity distribution of the interstellar radiation background is based on the observational data from IRAS, COBE-FIRAS and Planck. The intensity of this radiation field increases rapidly towards the Galactic plane and is the highest near the Galactic centre due to the high density of stars and dust. However, a precise determination of the variations of this radiation field with spatial and angular coordinates is not feasible observationally. We explore how future studies of gamma-ray spectra from numerous ultra-high-energy gamma-ray sources can indirectly probe variations in the interstellar radiation field's intensity across different distances from the Galactic centre and across Galactic latitudes and longitudes. This study is crucial for making self-consistent predictions of high energy gamma-ray fluxes from Galactic sources detected by observatories like LHAASO, Tibet AS$_{\gamma}$ and the next-generation gamma-ray telescopes.

The binary Yarkovsky effect on the secondary asteroid (BYS) was recently discovered to influence binary asteroid systems by pushing the secondary asteroid toward a synchronous orbit on a short timescale. However, the binary Yarkovsky effect on the primary (BYP) remains less understood, partly due to non-linear effects from partial eclipses, but could have significant implications for singly synchronous binaries. In this work, we studied the BYP effect by numerical methods and estimated its induced orbital drifting rates for real binary asteroids. We find an empirical modified solution to estimate the effective BYP: the traditional BYP formula multiplied by $(r_s / r_p)^(\alpha -1 )$. We confirm that the BYP pushes the primary towards a synchronous orbit where its spin equals the mean motion. The parameter $\alpha$ is insensitive to the ratio of the spin rate to the mean motion and decreases slightly with increasing thermal inertia. For small binary systems with a typical thermal inertia of 200 tiu, $\alpha$ is approximately 1.7. The BYP is found to affect the mutual orbit of singly synchronous binaries with a timescale typically an order of magnitude longer than that of the BYS. Drift rates induced by the BYP for known small binary asteroids (primary radius < 1 km) range from -0.001 to -1 cm $yr^{-1}$. A comparative analysis with observed orbital drift rates shows agreement for pre-impact Didymos and 1996 FG$_3$ but discrepancies for 2001 SL$_9$ and 1999 KW$_4$, suggesting complex dynamics in these systems involving the BYP, the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, and tides. The BYP is changing the mutual orbits of most discovered binary asteroids. We suggest that the BYP should be considered along with BYORP and tidal effects when studying binary systems' long-term dynamics.

The existence of massive white dwarfs (WDs) containing more than Chandrasekhar's maximum mass has been suggested via the detection of peculiar type Ia Supernovae. It had been crucial to directly detect those 'super' (more massive)-Chandrasekhar WDs to confirm their existence. The WD's small size and cold internal environment have been a great disadvantage for detecting them via electromagnetic surveys like GAIA and SDSS. Although many WDs are detected in optical observations, none of the super-Chandrasekhar WDs was observed directly. Mukhopadhyay and his group proposed a decade ago that one of the possibilities to explain the high mass of super-Chandrasekhar WD is to exercise the existence of a strong magnetic field in the WD interior. The group also recently proposed that a high magnetic field, in turn, can nontrivially deform the star from a spherical shape. In the presence of rotation and obliquity angle, such WDs can radiate continuous gravitational waves (CGW). This opens up the exciting possibility of detecting the super-Chandrasekhar WDs with the upcoming detector LISA. However, the gravitational wave (GW) amplitude will decay with time due to electromagnetic radiation and quadrupolar radiation. Altogether, those decay mechanisms will set a timescale for detecting WDs via CGW. Even with a timescale bound, we can expect to detect a few super-Chandrasekhar WDs with a couple of years of cumulative detection, leading to the direct detection of super-Chandrasekhar WDs.

The basic framework of the superfluid vortex model for pulsar glitches, though, is well accepted; there is a lack of consensus on the possible trigger mechanism responsible for the simultaneous release of a large number ($\sim 10^{17}$) of superfluid vortices from the inner crust. Here, we propose a simple trigger mechanism to explain such catastrophic events of vortex unpinning. We treat a superfluid vortex line as a classical massive straight string with well-defined string tension stretching along the rotation axis of pulsars. The crustquake-induced lattice vibration of the inner crust can act as a driving force for the transverse oscillation of the string. Such forced oscillation near resonance causes the bending of the vortex lines, disturbing their equilibrium configuration and resulting in the unpinning of vortices. We consider unpinning from the inner crust's so-called {\it strong (nuclear)} pinning region, where the vortices are likely pinned to the nuclear sites. We also comment on vortex unpinning from the interstitial pinning region of the inner crust. We sense that unifying crustquake with the superfluid vortex model can naturally explain the cause of large-scale vortex unpinning and generation of large-size pulsar glitches.

The heating of the solar corona and solar wind, through suprathermal particles and kinetic Alfvén waves within the 0 - 10 $R_{\rm Sun}$ range, has been a subject of great interest for many decades. This study investigates the acceleration and heating of charged particles and the role of KAWs in the solar corona. We investigate how KAWs transport energy and accelerate/heat the charged particles, focusing on the behavior of perturbed EM fields, Poynting flux vectors, net power transfer, resonant particle speed, group speed, and the damping length of KAWs. The study examines how these elements are influenced by suprathermal particles \kappa and the electron-to-ion temperature $T_e/T_i$. We use kinetic plasma theory coupled with the Vlasov-Maxwell model to investigate the dynamics of KAWs and particles. We assume a collisionless, homogeneous, and low-beta electron-ion plasma in which Alfvén waves travel in the kinetic limits. The results show the perturbed EM fields are significantly influenced by $\kappa$ and $T_e/T_i$. We evaluate both the parallel and perpendicular Poynting fluxes and find that the parallel Poynting flux dissipates gradually for lower \kappa values. The perpendicular flux dissipates quickly over shorter distances. Power deposition in solar flux tubes is significantly influenced by \kappa and Te/Ti. We find that particles can heat the solar corona over long distances in the parallel direction and short distances in the perpendicular direction. The group velocity of KAWs increases for lower \kappa values, and the damping length is enhanced under lower \kappa, suggesting longer energy transport distances. These findings offer a comprehensive understanding of particle-wave interactions in the solar corona and wind, with potential applications for missions such as the Parker Solar Probe (PSP), and can also apply to other environments.

Context. Binary star systems allow us to study the planet formation process under extreme conditions. In the early stages, these systems contain a circumbinary disk and a disk around each star. To model the interactions between these disks in the frame of one of the stars, strong fictitious forces must be included in the simulations. The original Fargo and the Fargo3D codes fail to correctly simulate such systems if the indirect term becomes too strong. Aims. We present a different way to compute the indirect term which, together with a tensor artificial viscosity prescription, allows the Fargo code to simulate the circumbinary disks in a non-inertial frame of reference. In this way, the Fargo code can be used to study interactions between circumstellar and circumbinary disks. Results. We find that updating the indirect term becomes relevant when the indirect term becomes stronger than the direct gravitational forces, which occurs for mass ratios of $q > 5\%$. The default artificial viscosity used in the Fargo code inherently produces artificial pressure in a non-inertial frame of reference even in the absence of shocks. This leads to artificial mass ejection from the Hill sphere, starting at brown dwarf masses ($q > 1\%$). These problems can be mitigated by using a tensor artificial viscosity formulation. For high mass ratios, $q > 1\%$, it is also becomes important to initialize the disk in the center-of-mass frame. We expect our proposed changes to be relevant for other grid-based hydrodynamic codes where strong indirect terms occur, or for codes that use artificial viscosity.

The Hercules kinematic group is a kinematic anomaly of stars observed in the solar neighbourhood (SNd). In this series of papers, we present a comprehensive study of this structure. This paper focuses on its chemical signatures over several groups of elements. The next paper discusses its kinematical properties. While studies suggested a non-native origin of Hercules stars due to the distinct chemical and kinematic features, previous studies focussed mainly on the Fe abundances. We adopt chemical data with abundances of elements from APOGEE and GALAH to seek further chemical evidence of the origin. Our analysis reveals that the low alpha population of the low angular momentum Hercules group is significantly enhanced in iron-peak (Fe, Ni, Mn) and odd-Z (Na, Al) elements, and slightly deficient in alpha elements (O, Ca, Ti) compared to kinematically local stars. The super enhancement in iron-peak elements and deficiency in alpha elements support their origin from the outer thin bar in the inner Galaxy. Moreover, the enhancement in Na and Al indicates these stars as the youngest stars in the old sequence from the inner thick disc. Hence, the origin of these stars can be related to the outer bar region. These chemical signatures require the underlying dynamical mechanism that forms the Hercules group to be capable of transporting stars in the inner Galaxy out to the SNd. The next paper will consider the Trojan orbits as the favoured mechanism.

The Hercules structure is a stellar kinematic group anomaly observed in the solar neighbourhood (SNd). In the previous paper, we analysed chemical signatures and related the origin of this stellar population to the outer bar. Next to consider is how this alien population migrate out into the SNd. Often, the formation of this kinematic structure is associated with bar resonances. In this paper, We consider the driving mechanism of Hercules on the orbital level. We construct a simple Milky Way-like potential model with a slowly rotating long bar and explore some of the stellar orbit families and their stability. With this model, our numerical solutions of the equations of motion show that extended quasi-periodic orbits trapped around fast-rotating periodic orbits around the L4 Lagrange point of the bar minor axis can pass through the SNd. When observed in the SNd, they populate the Hercules structure in the Lz-Vr kinematics space. Moreover, the variation in radial coverage in the galactic plane with the SNd kinematics shows good agreement with chemical signatures found in Paper I. Furthermore, the effective potential shows the topology of a volcano, the rim of which limits most orbits to stay inside or outside. Trojan orbits are a stable orbit family that can transport inner Galactic stars out to the SNd. They can explain the stellar kinematics of the Hercules group, and provide a straightforward basis for its chemical properties (see Paper I). We support the view that Trojan orbits associated with the slowly rotating Galactic bar explain the Hercules structure observed in SNd.

The dynamic of relativistic jets in the inner parsec regions is deeply affected by the nature of the magnetic fields. The level of magnetization of the plasma, as well as the geometry of these fields on compact scales, have not yet been fully constrained. In this paper we employ multi-frequency and multi-epoch very long baseline interferometry observations of the nearby radio galaxy NGC 315. We aim to derive insights into the magnetic field properties on sub-parsec and parsec scales by examining observational signatures such as the spectral index, synchrotron turnover frequency, and brightness temperature profiles. This analysis is performed by considering the properties of the jet acceleration and collimation zone, which can be probed thanks to the source vicinity, as well as the inner part of the jet conical region. We observe remarkably steep values for the spectral index on sub-parsec scales ($\alpha \sim -2$, $S_\nu \propto \nu^\alpha$) which flatten around $\alpha \sim -0.8$ on parsec scales. We suggest that the observed steep values may result from particles being accelerated via diffusive shock acceleration mechanisms in magnetized plasma and subsequently experiencing cooling through synchrotron losses. The brightness temperature of the 43 GHz cores indicates a dominance of the magnetic energy at the jet base, while the cores at progressively lower frequencies reveal a gradual transition towards equipartition. Based on the spectral index and brightness temperature along the incoming jet, and by employing theoretical models, we derive that the magnetic field strength has a close-to-linear dependence with distance going from parsec scales up to the jet apex. Overall, our findings are consistent with a toroidal-dominated magnetic field on all the analyzed scales.

Interactions between magma oceans and overlying atmospheres on young rocky planets leads to an evolving feedback of outgassing, greenhouse forcing, and mantle melt fraction. Previous studies have predominantly focused on the solidification of oxidized Earth-similar planets, but the diversity in mean density and irradiation observed in the low-mass exoplanet census motivate exploration of strongly varying geochemical scenarios. We aim to explore how variable redox properties alter the duration of magma ocean solidification, the equilibrium thermodynamic state, melt fraction of the mantle, and atmospheric composition. We develop a 1D coupled interior-atmosphere model that can simulate the time-evolution of lava planets. This is applied across a grid of fixed redox states, orbital separations, hydrogen endowments, and C/H ratios around a Sun-like star. The composition of these atmospheres is highly variable before and during solidification. The evolutionary path of an Earth-like planet at 1 AU ranges between permanent magma ocean states and solidification within 1 Myr. Recently solidified planets typically host H2O- or H2-dominated atmospheres in the absence of escape. Orbital separation is the primary factor determining magma ocean evolution, followed by the total hydrogen endowment, mantle oxygen fugacity, and finally the planet's C/H ratio. Collisional absorption by H2 induces a greenhouse effect which can prevent or stall magma ocean solidification. Through this effect, as well as the outgassing of other volatiles, geochemical properties exert significant control over the fate of magma oceans on rocky planets.

Deconvolution of astronomical images is a key aspect of recovering the intrinsic properties of celestial objects, especially when considering ground-based observations. This paper explores the use of diffusion models (DMs) and the Diffusion Posterior Sampling (DPS) algorithm to solve this inverse problem task. We apply score-based DMs trained on high-resolution cosmological simulations, through a Bayesian setting to compute a posterior distribution given the observations available. By considering the redshift and the pixel scale as parameters of our inverse problem, the tool can be easily adapted to any dataset. We test our model on Hyper Supreme Camera (HSC) data and show that we reach resolutions comparable to those obtained by Hubble Space Telescope (HST) images. Most importantly, we quantify the uncertainty of reconstructions and propose a metric to identify prior-driven features in the reconstructed images, which is key in view of applying these methods for scientific purposes.

Deuterium was primarily created during the Big Bang Nucleosynthesis (BBN). This fact, alongside its fractionation reactions resulting in enhanced abundances of deuterated molecules, means that these abundances can be used to better understand many processes within the interstellar medium (ISM), as well as its history. Previously, observations of deuterated molecules have been limited to the Galaxy, the Magellanic Clouds and (with respect to HD) to quasar absorption spectra. We present the first robust detection of a deuterated molecule in a starburst environment and, besides HD, the first one detected outside the Local Group. We therefore can constrain the deuterium fractionation, as observed by DCN. We observed the CMZ of the nearby starburst galaxy NGC 253 covering multiple Giant Molecular Clouds (GMC) with cloud scale observations ($\sim 30$ pc) using ALMA. Via the use of the \texttt{MADCUBA} package we were able to perform LTE analysis in order to obtain deuterium fractionation estimates. We detect DCN in the nuclear region of the starburst galaxy NGC 253 and estimate the deuterium fractionation (D/H ratio) of DCN within the GMCs of the CMZ of NGC 253. We find a range of $5 \times 10^{-4}$ to $10 \times 10^{-4}$, relatively similar to the values observed in warm Galactic star-forming regions. We also determine an upper limit of D/H of $8 \times 10^{-5}$ from DCO\plus within one region, closer to the cosmic value of D/H. Our observations of deuterated molecules within NGC 253 appear to be consistent with previous galactic studies of star forming regions. This implies that warmer gas temperatures increase the abundance of DCN relative to other deuterated species. This study also further expands the regions, particularly in the extragalactic domain, in which deuterated species have been detected.

The abundances resulting from $r$-process nucleosynthesis as predicted by simulations of binary neutron-star (BNS) mergers remain an open question as the current state-of-the-art is still restricted to three-species neutrino transport. We present the first BNS merger simulations employing a moment-based general-relativistic neutrino transport with five neutrino species, thus including (anti)muons and advanced muonic $\beta$-processes, and contrast them with traditional three neutrino-species simulations. Our results show that a muonic trapped-neutrino equilibrium is established, forming a different trapped-neutrino hierarchy akin to the electronic equilibrium. The formation of (anti)muons and the muonization via muonic $\beta$-processes enhance the neutrino luminosity, leading to rapid cooling in the early post-merger phase. Since muonic processes redirect part of the energy otherwise used for protonization by electronic processes, they yield a cooler remnant and disk, together with neutrino-driven winds that are more neutron-rich. Importantly, the unbound ejected mass is smaller than three-species simulations and, because of its comparatively smaller temperature and proton fraction, it can enhance lanthanide production and reduce the overproduction of light $r$-process elements for softer equations of state. This finding underlines the importance of muonic interactions and five neutrino species in long-lived BNS remnants.

The assumption of a flat universe that follows the cosmological principle, i.e., that the universe is statistically homogeneous and isotropic at large scales, comprises one of the core foundations of the standard cosmological model -- namely, the $\Lambda$CDM paradigm. Nevertheless, it has been seldom tested in the literature. In this work, we assess the validity of this hypothesis by reconstructing the cosmic curvature with currently available observations, such as Type Ia Supernova and Cosmic Chronometers. We do so by means of null tests, given by consistency relations within the standard model scenario, using a non-parametric method -- which allows us to circumvent prior assumptions on the underlying cosmology. We find no statistically significant departure from the cosmological principle and null curvature in our analysis. In addition, we show that future cosmological observations, such as those expected from Hubble parameter measurements from redshift surveys, along with gravitational wave observations as standard sirens, will be able to significantly reduce the uncertainties of current reconstructions.

Our study aims to elucidate both short-term and long-term variations in the light curve of the eclipsing system OGLE-LMC-ECL-14413, with a particular focus on the unusual reversals in eclipse depth. We aim to clarify the role of the accretion disk in these fluctuations, especially in long-cycle changes spanning hundreds of days. Additionally, we seek to determine the evolutionary stage of the system and gain insights into the internal structure of its stellar components. We analyzed photometric time series from the Optical Gravitational Lensing Experiment (OGLE) project in the I and V bands, and from the MAssive Compact Halo Objects project in the BM and RM bands, covering a period of 30.85 years. Using light curve data from 27 epochs, we constructed models of the accretion disk. An optimized simplex algorithm was employed to solve the inverse problem, deriving the best-fit parameters for the stars, orbit, and disk. We also utilized the Modules for Experiments in Stellar Astrophysics software to assess the evolutionary stage of the binary system, investigating the progenitors and potential future developments. We found an orbital period of 38.15917(54) d and a long-term cycle of approximately 780 d. Temperature, mass, radius, and surface gravity values were determined for both stars. The photometric orbital cycle and the long-term cycle are consistent with a disk containing variable physical properties, including two shock regions. The disk encircles the more massive star and the system brightness variations align with the long-term cycle at orbital phase 0.25. Our mass transfer rate calculations correspond to these brightness changes. \texttt{MESA} simulations indicate weak magnetic fields in the donor star's subsurface, which are insufficient to influence mass transfer rates significantly.

Blue-tilted Gravitational Waves (BGWs) have been proposed as a potential candidate for the cosmic gravitational waves detected by Pulsar Timing Arrays (PTA). In the standard cosmological framework, BGWs are constrained in their frequency range by the Big Bang Nucleosynthesis (BBN) limit on GW amplitude, which precludes their detection at interferometer scales. However, introducing a phase of early matter domination dilutes BGWs at higher frequencies, ensuring compatibility with both the BBN and LIGO constraints on stochastic GWs. This mechanism allows BGWs to align with PTA data while producing a distinct and testable GW signal across a broad frequency spectrum. Ultralight Primordial Black Holes (PBHs) could provide the required early matter-dominated phase to support this process. Interpreted through the lens of BGWs, the PTA results offer a way to constrain the parameter space of a new scenario involving modified Hawking radiation, known as the ``memory burden" effect, associated with ultralight PBHs. This interpretation can be further probed by high-frequency GW detectors. Specifically, we demonstrate that PBHs as light as $10^{2-3}~{\rm g}$ can leave detectable imprints on BGWs at higher frequencies while remaining consistent with PTA observations.

A key to understand exoplanets is characterisation of their host stars. One of the most powerful tools to characterise stellar properties like effective temperature, surface gravity and metallicity, is spectroscopy based on observations of stellar atmospheres. This chapter describes the stellar parameters that can be derived from a spectrum with examples of well established methods and theoretical model atmospheres. Combined with photometry and parallax measurements, the outcome of the spectroscopic modelling can be used to derive stellar radii and masses.

Some Active Galactic Nuclei (AGN) host outflows which have the potential to alter the host galaxy's evolution (AGN feedback). These outflows have been linked to enhanced radio emission. Here we investigate the connection between low-frequency radio emission using the International LOFAR Telescope and [O III] $\lambda$5007 ionised gas outflows using the Sloan Digital Sky Survey. Using the LOFAR Two-metre Sky Survey (LoTSS) Deep Fields, we select 198 AGN with optical spectra, 115 of which are detected at 144 MHz, and investigate their low-frequency radio emission properties. The majority of our sample do not show a radio excess when considering radio luminosity - SFR relationship, and are therefore not driven by powerful jets. We extract the [O III] $\lambda$5007 kinematics and remove AGN luminosity dependencies by matching the radio detected and non-detected AGN in $L_{\mathrm{6\mu m}}$ and redshift. Using both spectral fitting and $W_{80}$ measurements, we find radio detected AGN have a higher outflow rate (67.2$\pm$3.4 percent) than the radio non-detected AGN (44.6$\pm$2.7 percent), indicating a connection between ionised outflows and the presence of radio emission. For spectra where there are two components of the [O III] emission line present, we normalise all spectra by the narrow component and find that the average broad component in radio detected AGN is enhanced compared to the radio non-detected AGN. This could be a sign of higher gas content, which is suggestive of a spatial relationship between [O III] outflows and radio emission in the form of either low-powered jets or shocks from AGN winds.

In binary neutron star mergers, the remnant can be stabilized by differential rotation before it collapses into a black hole. Therefore, the angular momentum transport mechanisms are crucial for predicting the lifetime of the hypermassive neutron star. One such mechanism is the Tayler-Spruit dynamo, and recent simulations have shown that it could grow in proto-neutron stars formed during supernova explosions. We aim to investigate whether hypermassive neutron stars with high neutrino viscosity could be unstable to the Tayler-Spruit dynamo and study how magnetic fields would evolve in this context. Using a one-zone model based on the result of a 3D GRMHD simulation, we investigate the time evolution of the magnetic fields generated by the Tayler-Spruit dynamo. In addition, we analyze the dynamics of the 3D GRMHD simulation to determine whether the dynamo is present. Our one-zone model predicts that the Tayler-Spruit dynamo can increase the toroidal magnetic field to $ \ge 10^{17}$ G and the dipole field to amplitudes $\ge 10^{16}$ G. The dynamo's growth timescale depends on the initial large-scale magnetic field right after the merger. In the case of a long-lived hypermassive neutron star, an initial magnetic field of $\ge 10^{12}$ G would be enough for the magnetic field to be amplified in a few seconds. However, we show that the resolution of the current GRMHD simulations is insufficient to resolve the Tayler-Spruit dynamo due to high numerical dissipation at small scales. We find that the Tayler-Spruit dynamo could occur in hypermassive neutron stars and shorten their lifetime, which would have consequences on multi-messenger observations.

Red Supergiants (RSGs) are cool, evolved massive stars in the last evolutionary stage before exploding as a supernova. However, the most luminous RSGs may evolve blueward before exploding, given the observational evidence for luminous, warm, post-RSG objects and the lack of supernova progenitors originating from luminous RSGs. In this work, we analyze WOH G64, considered since the 1980s as the most extreme RSG in the Large Magellanic Cloud in terms of its size, luminosity, and mass-loss rate. Time-series photometry over the last 30 years reveals a sudden, yet smooth change from semi-regular to irregular variability in 2014. Multi-epoch optical spectroscopy confirms the transition, as WOH G64 now exhibits properties of a B[e] star in the optical, and warm-star features in the near-infrared. We report that WOH G64 has transitioned from a RSG to a Yellow Hypergiant and, moreover, has a B-star companion. The dramatic transition can be explained by: a) binary interactions partially stripping the envelope, b) the return of WOH G64 to a quiescent state after an outstanding eruption exceeding 30 years, and c) the expulsion of its outer layers due to a pre-SN superwind phase, indicating its imminent explosion. WOH G64 offers a unique opportunity to witness stellar evolution in real-time, providing crucial clues for the late phases of massive stars and their resulting supernovae.

We report the first, direct measurement of the electron density turbulence parameter $C_1$, enabled by 550-750 MHz observations with the upgraded Giant Metrewave Radio Telescope. The parameter $C_1$ depends on the power law index of the wavenumber spectrum of electron density inhomogeneities in the ionized interstellar medium. Radio waves propagating through the inhomogeneous ionized medium suffer multipath propagation, as a result of which the pulsed emission from a neutron star undergoes scatter broadening. Consequently, interference between the delayed copies of the scatter-broadened electric field manifests as scintillation. We measure a scintillation bandwidth $\Delta\nu_d=149\pm3$ Hz as well as a scatter-broadening timescale $\tau_d=1.22\pm0.09$ ms at 650 MHz towards the magnetar XTE J1810-197, using which we estimate $C_1=1.14\pm0.09$ directly from the uncertainty relation. This is also the first reported direct measurement of a scintillation bandwidth of order 100 Hz. We describe the methods employed to obtain these results and discuss their implications in general, as well as for the magnetar XTE J1810-197. We also discuss how such, effectively in-situ, measurements of $C_1$ can aid in inferring the wavenumber spectrum power law index, and hence, quantitatively discriminate between the various possible scattering scenarios in the ionized medium.

The first "seeds" of supermassive black holes (BHs) continue to be an outstanding puzzle, and it is currently unclear whether the imprints of early seed formation survive today. Here we examine the signatures of seeding in the local Universe using five $[18~\mathrm{Mpc}]^3$ BRAHMA simulation boxes run to $z=0$. They initialize $1.5\times10^5~M_{\odot}$ BHs using different seeding models. The first four boxes initialize BHs as heavy seeds using criteria that depend on dense & metal-poor gas, Lyman-Werner radiation, gas spin, and environmental richness. The fifth box initializes BHs as descendants of lower mass seeds ($\sim10^3~M_{\odot}$) using a new stochastic seed model built in our previous work. We find that strong signatures of seeding survive in $\sim10^5-10^6~M_{\odot}$ local BHs hosted in $M_*\lesssim10^{9}~M_{\odot}$ dwarf galaxies. The signatures survive due to two reasons: 1) there is a substantial population of local $\sim10^5~M_{\odot}$ BHs that are ungrown relics of early seeds from $z\sim5-10$; 2) BH growth up to $\sim10^6~M_{\odot}$ is dominated by mergers all the way down to $z\sim0$. As the contribution from gas accretion increases, the signatures of seeding start to weaken in more massive $\gtrsim10^6~M_{\odot}$ BHs, and they eventually disappear for $\gtrsim10^7~M_{\odot}$ BHs. This is in contrast to high-z ($z\gtrsim5$) BH populations wherein the BH growth is fully merger dominated, which causes the seeding signatures to persist at least up to $\sim10^8~M_{\odot}$. The different seed models predict abundances of local $\sim10^6~M_{\odot}$ BHs ranging from $\sim0.01-0.05~\mathrm{Mpc}^{-3}$ with occupation fractions of $\sim20-100\%$ in $M_*\sim10^{9}~M_{\odot}$ galaxies. Our results highlight the potential for local $\sim10^5-10^6~M_{\odot}$ BH populations in dwarf galaxies to serve as a promising probe for BH seeding models.

The stellar mass distribution in star-forming regions, stellar clusters and associations, the Initial Mass Function (IMF), appears to be invariant across different star-forming environments, and is consistent with the IMF observed in the Galactic field. Deviations from the field, or standard, IMF, if genuine, would be considered strong evidence for a different set of physics at play during the formation of stars in the birth region in question. We analyse N-body simulations of the evolution of spatially and kinematically substructured star-forming regions to identify the formation of binary star clusters, where two (sub)clusters which form from the same Giant Molecular Cloud orbit a common centre of mass. We then compare the mass distributions of stars in each of the subclusters and compare them to the standard IMF, which we use to draw the stellar masses in the star-forming region from which the binary cluster(s) form. In each binary cluster that forms, the mass distributions of stars in one subcluster deviates from the standard IMF, and drastically so when we apply similar mass resolution limits as for the observed binary clusters. Therefore, if a binary subcluster is observed to have an unusual IMF, this may simply be the result of dynamical evolution, rather than different physical conditions for star formation in these systems.

This paper aims to present the time-dependent coupling between the coronal model COolfluid COroNal UnsTructured (COCONUT) and the heliospheric forecasting tool EUHFORIA. We perform six COCONUT simulations where a flux rope is implemented at the solar surface using either the Titov-Démoulin CME model or the Regularized Biot-Savart Laws (RBSL) CME model. At regular intervals, the magnetic field, velocity, temperature, and density of the 2D surface $R_{b}=21.5~\;R_{\odot}$ are saved in boundary files. This series of coupling files is read in a modified version of EUHFORIA to update progressively its inner boundary. After presenting the early stage of the propagation in COCONUT, we examine how the disturbance of the solar corona created by the propagation of flux ropes is transmitted into EUHFORIA. In particular, we consider the thermodynamic and magnetic profiles at L1 and compare them with those obtained at the interface between the two models. We demonstrate that the properties of the heliospheric solar wind in EUHFORIA are consistent with those in COCONUT, acting as a direct extension of the coronal domain. Moreover, the disturbances initially created from the propagation of flux ropes in COCONUT continue evolving from the corona in the heliosphere to Earth with a smooth transition at the interface between the two simulations. Looking at the profile of magnetic field components at Earth and different distances from the Sun, we also find that the transient magnetic structures have a self-similar expansion in COCONUT and EUHFORIA. However, the amplitude of the profiles depends on the flux rope model used and its properties, thus emphasizing the important role of the initial properties in solar source regions for accurately predicting the impact of CMEs.

We present a status report of our intensive and long-term UBV RI photometric monitoring of nova KT Eri since its outbust in 2009. The old-nova in quiescence is characterized by very high excitation conditions (HeII 4686 being constantly the strongest emission line in optical spectra) and a complex-pattern photometric variability of one mag amplitude in which multi-periodicities (from hours to years) are mixed with chaotic activity of similar amplitude. Mean color and brightness levels are the same for pre- and post- outburst quiescence.

Baryon Acoustic Oscillation (BAO) provides a powerful tool to measure cosmic expansion and consequently the nature of the Dark Energy (DE). Recent precise BAO measurements by Dark Energy Spectroscopic Instrument data release 1 (DESI DR1), when combined with Cosmic Microwave Background (CMB) data from Planck and Supernovae of Type Ia (SN Ia), favor evolving dark energy over cosmological constant. This result is strongly related to the assumed priors on the Chevallier-Polarski-Linder (CPL) parameterization of DE. We test another parametrization which introduces two free parameters $n$ and $\alpha$, only $n$ is independent. Thus, it reduces the parameter space compared to the CPL model, which derives a more robust preference for evolving DE, if any. The model potentially produces three cosmological scenarios according to the values of its parameters. For $n=3$, the $\Lambda$CDM model is recovered, quintessence for $n<3$, and phantom for $n>3$. In the present study, we test the model on the background level, and, to our knowledge for the first time, on the linear perturbation level. Bayesian evidence analysis shows a weak preference for dynamical DE in the phantom regime over the cosmological constant DE using Planck, DESI, and PantheonPlus\&SH0ES data. The model predicts current phantom DE $w_{de,0} = -1.073 \pm 0.032$ and $H_0=70.9\pm 1.4$ km/s/Mpc when Planck+DESI data is used, which decreases the tension with $H_0$ local measurements to $1.2\sigma$ level.

The exceptionally low mass of $0.77_{-0.17}^{+0.2} M_{\odot}$ for the central compact object (CCO) XMMU J173203.3 -- 344518 (XMMU J1732) in the supernova remnant (SNR) HESS J1731 -- 347 challenges standard neutron star (NS) formation models. The nearby post-AGB star IRAS 17287 -- 3443 ($\approx 0.6 M_\odot$), also within the SNR, enriches the scenario. To address this puzzle, we advance the possibility that the gravitational collapse of a rotating pre-SN iron core ($\approx 1.2 M_\odot$) could result in a low-mass NS. We show that angular momentum conservation during the collapse of an iron core rotating at $\approx 45\%$ of the Keplerian limit results in a mass loss of $\approx 0.3 M_\odot$, producing a stable newborn NS of $\approx 0.9 M_\odot$. Considering the possible spin-down, this indicates that the NS is now slowly rotating, thus fulfilling the observed mass-radius relation. Additionally, the NS's surface temperature ($\approx 2 \times 10^6$ K) aligns with canonical thermal evolution for its $\approx 4.5$ kyr age. We propose the pre -- SN star, likely an ultra-stripped core of $\approx 4.2 M_\odot$, formed a tidally locked binary with IRAS 17287 -- 3443, having a 1.43-day orbital period. The supernova led to a $\approx 3 M_\odot$ mass loss, imparting a kick velocity $\lesssim 670$ km s$^{-1}$, which disrupted the binary. This scenario explains the observed 0.3 pc offset between XMMU J1732 and IRAS 17287 -- 3443 and supports the possibility of CCOs forming in binaries, with rotation playing a key role in core-collapse, and the CCO XMMU J1732 being the lightest NS ever observed.

We present the discovery and analysis of a nearby eclipsing ultra-compact accreting binary at coordinates 11:38:10.91 $-$51:39:49.15 (SMSS J1138$-$5139), the first well-constrained LISA-detectable Type Ia supernova progenitor. Our time series optical spectroscopy identifies its orbital period through radial velocity monitoring at $P_{\rm orb,RV}=27.69\pm0.03~{\rm min}$; twice the photometric period seen in 2-minute cadence data from TESS Sector 37. We model our optical spectroscopy together with new simultaneous multi-band time series photometry from Gemini to place constraints on the binary parameters. Our light curve modeling finds that SMSS J1138$-$5139 contains an $M_2=0.24~{\rm M_\odot}$ pre-white dwarf donor with a massive $M_1=0.99~{\rm M_\odot}$ white dwarf accretor at orbital inclination $i=88.7~{\rm deg}$. Based on our photometrically derived system parameters, we expect that gravitational wave radiation will drive SMSS J1138$-$5139 to a merger within $\tau=5.7\pm0.3~{\rm Myr}$ and result in a Type Ia supernova. Even without a direct merger event, the component masses of SMSS J1138$-$5139 and active hydrogen accretion suggest that eventual helium accretion will likely also trigger a Type Ia supernova explosion through the dynamically-driven double-degenerate double-detonation (D6) channel. We expect LISA to detect the gravitational wave emission from SMSS J1138$-$5139 with signal-to-noise $7-10$ after a 48-month mission.

Current studies of large-scale asymmetries (i.e. lopsidedness) in the stellar density distribution of disk galaxies have mainly focused on the local Universe. Recent observations have found a significant fraction (over 60%) of lopsided galaxies at high-redshift ($1.5 < z < 3$), which is significantly larger than the fraction (~30%) observed in the nearby Universe. We aim to understand whether the more widespread lopsidedness at high- than low-redshift can be associated to environmental mechanisms being more effective in producing lopsided perturbations at high-redshift. At each redshift between $0 < z < 2$, we independently select a sample of disk-like galaxies from the IllustrisTNG simulations. We then characterize lopsidedness in the disks of galaxies at each redshift, study the relevant mechanisms generating lopsidedness, as well as the correlation between such perturbation, the local environment and the galaxy internal properties as a function of redshift. Consistent with previous and new observational results, we find that: 1) simulations predict a significant fraction (~60%) of lopsided galaxies at high-redshift ($1.5 < z < 2$), 2) the fraction of lopsided galaxies, as well as the lopsided amplitude, decreases from high- to low-redshift, and 3) there is not a significant dependence of lopsidedness on the local environment, but there is a strong correlation between the lopsided amplitude and basic galaxies' structural properties at all redshift between $0 < z < 2$. This means that, independent of the mechanisms on-setting lopsidedness, galaxies with low central stellar mass density and more extended disks are more susceptible of developing strong lopsidedness. We find that both recent interactions with mass-ratio >1:10 and gas accretion with subsequent star formation can produce lopsided perturbations at all redshift, but they are both significantly more effective at high-redshift.

The QCD axion, originally proposed to solve the strong CP problem in QCD, is a prominent candidate for dark matter (DM). In the presence of strong magnetic fields, such as those around neutron stars, axions can theoretically convert into photons, producing detectable electromagnetic signals. This axion-photon coupling provides a unique experimental pathway to probe axions within a specific mass range. We investigate a novel observational approach using the Green Bank Telescope (GBT) to search for radio transients that could arise from interactions between neutron stars and dense DM clumps known as axion miniclusters. By observing the core of Andromeda with the VErsatile GBT Astronomical Spectrometer (VEGAS) and the X-band receiver (8 to 10 GHz), we achieve sensitivity to axions with masses in the range of (33 - 42)$\,\mu$eV, with a mass resolution of $3.8 \times 10^{-4}\,\mu$eV. We detail our observational and analytical strategies developed to capture transient signals from axion-photon conversion, achieving an instrumental sensitivity of $2\,$mJy per spectral channel. Despite our sensitivity threshold, no candidate signals exceeding the 5$\sigma$ level were identified. Future implementations will extend this search across additional spectral bands and refine the modeling used for the processes involved, strengthening the constraints on axion DM models.

We present a global census of metals in the Universe and their evolution with cosmic time, synthesizing robust estimates of metals in stars, hot intra-cluster gas, and gaseous absorbers tracing neutral gas as well as ionized gas in the circumgalactic and intergalactic media. We observe a 13-fold increase in the stellar metal mass density from z~2.5 to 0.7, over which time stars emerge as the most important metal reservoir at low redshifts, housing ~31% of the total expected metal density at z~0.1. Hot virialized intracluster/intragroup gas accounts for ~15% and 10% of metals at z~0.1 and 0.7, respectively. Using metallicity measurements from CCC, KODIAQ-Z, and HD-LLS surveys covering redshifts z<1 to z~2-3.5 we investigate the global distribution of metals in extragalactic ionized gas as a function of HI column density. During the period from z~3 to z<1, the global metal density of cool (T~10^{4-5} K) gas has doubled. However, the fractional contribution of the ionized gas to the total expected metal density decreased from ~20% at z~3 to ~4% at z<1. The cosmic metal density of all gas phases has increased with cosmic time, reflecting an "inside-out" metal dispersion by feedback mechanisms and galactic outflows.

Peculiar velocities are the motions of galaxies due to the gravitational influence of large-scale structure, and thus are an important cosmological probe of the underlying matter density field. In recent years the number of surveys designed to measure peculiar velocities has increased, to the point that it is plausible that we will have completely mapped out the peculiar velocity field in the local universe within the next decade. Such an abundance of data will enable us to place precise constraints on the growth rate of large-scale structure which in turn will inform us about the true nature of the laws of gravity and the standard cosmological model. In this chapter, the physics governing the generation of peculiar velocities, the methods of measuring them, and the statistical tools used to extract cosmological information from them are described. It will also cover a swathe of current and future surveys dedicated to collecting peculiar velocities, what their aims are, and what these datasets may mean for the future of cosmological analyses.

The production of silicon monoxide (SiO) can be considered as a fingerprint of shock interaction. In this work, we use high-sensitivity observations of the SiO (2-1) and H$^{13}$CO$^{+}$ (1-0) emission to investigate the broad and narrow SiO emission toward 146 massive star-forming regions in the ATOMS survey. We detected SiO emission in 136 regions and distinguished broad and narrow components across the extension of 118 sources (including 58 UC $H_{II}$ regions) with an average angular resolution of 2.5$^{\prime}$$^{\prime}$. The derived SiO luminosity ($L_{SiO}$) across the whole sample shows that the majority of $L_{SiO}$ (above 66$\%$) can be attributed to broad SiO, indicating its association with strong outflows. The comparison of the ALMA SiO images with the filamentary skeletons identified from H$^{13}$CO$^{+}$ and in the infrared data (at 4.5, 8, and 24 $mu$m), further confirms that most SiO emission originates from outflows. However, note that for nine sources in our sample, the observed SiO emission may be generated by expanding UC $H_{II}$ regions. There is a moderate positive correlation between the bolometric luminosity ($L_{bol}$) and $L_{SiO}$ for both components (narrow and broad). The UC $H_{II}$ sources show a weaker positive correlation between $L_{bol}$ and $L_{SiO}$ and higher $L_{SiO}$ compared to the sources without UC $H_{II}$ regions. These results imply that the SiO emission from UC $H_{II}$ sources might be affected by UV-photochemistry induced by UC $H_{II}$ regions.

We examine the physical implications of the centrifugal and gravitational electromotive forces on magnetic reconnection in a Kerr black hole background. We find that both forces increase the reconnection rate, though the underlying mechanisms differ substantially. The gravitational force leads to a separation of charge density, breaking the quasi-neutrality of the plasma. In contrast, the centrifugal electromotive force affects the electric current by reducing the effective length of the current sheet. This reduction arises from the non-Euclidean spatial geometry observed by a locally comoving observer with respect to the rotating sheet. This phenomenon amplifies both the transport of charged carriers and the thermal-inertia effect within the current sheet, irrespective of the presence of a black hole.

To investigate the radio properties of the recently found high-redshift population, we collected a sample of $919$ little red dots (LRDs) from the literature. By cross-matching their coordinates with the radio catalogues based on the first- and second-epoch observations of the Very Large Array Sky Survey (VLASS) and the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey, we found no radio counterparts coinciding with any of the LRDs. To uncover possible sub-mJy level weak radio emission, we performed mean and median image stacking analyses of empty-field 'Quick Look' VLASS and FIRST image cutouts centred on the LRD positions. We found no radio emission above $3\sigma$ noise levels ($\sim11$ and $\sim18~\mu$Jy~beam$^{-1}$ for the VLASS and FIRST maps, respectively) in either of the stacked images for the LRD sample, while the noise levels of the single-epoch images are comparable to those found earlier in the stacking of high-redshift radio-quiet active galactic nuclei (AGNs). The non-detection of radio emission in LRDs suggests these sources host weaker (or no) radio AGNs.

High precision differential Astrometry is the branch of astronomy that evaluates the relative position, distance and motion of celestial objects with respect to the stars present in the field of view. A mission called Theia has been submitted in 2022 for ESA's M7 call for missions, using a diffraction-limited telescope about 1m in diameter and with a field of view of 0.5 degrees, capable of achieving sub-micro-arcsecond angular accuracy, corresponding to 1e-5 pixel on the detector. Such precision makes it possible to study the nature of dark matter in our galaxy and to reveal the architecture of exoplanetary systems close to the Sun, down to the mass of the Earth. The aim of the experimental tests presented in this poster is to improve the TRL of 2 specific aspects: the calibration of new CMOS detectors with very large number of pixels and the calibration of the telescope this http URL, a key element of such a space telescope is the focal plane, which must be calibrated spatially with an extreme precision down to the 1e-5 pixel level. Previous work has shown that this is possible with small detector matrices (80x80 px) [1]. The goal is now to check the performances and validate this method with the new very large detectors. Pyxalis, a company based near Grenoble, is developing very large detectors (8000x5000 px) that have a low noise level and high sensitivity. The aim is to characterize and validate this type of detectors in a laboratory demonstration (see poster Pancher et al.), to ensure that the performance achieved meets the required specifications. We present the results of these characterization in this this http URL telescope stability is also a sensitive issue. Recent work [2] has shown that the reference stars in the field of the telescope can be used as actual metrology sources in order to compute the field distortion function. Our simulations allow to model the optical aberrations with bivariate polynoms. The effects on the calibration accuracy of the degrees of the polynoms, the number of reference stars and the tilt perturbation of the M2 mirror are investigated. This poster will present the latest results obtained on a test bed developed to experimentally study the performances of this new field calibration method.

Quasars are objects of high interest for applications in extragalactic astrophysics, cosmology, and astrometry. One of their useful qualities is owed to their relativistic jets: they can be radio-loud. However, the fraction of radio-loud vs. radio-quiet quasars is subject to ongoing investigations, where the statistical power is limited by the low number of known quasars with radio counterparts. In this analysis, we revisited the radio-loudness statistics of quasars by significantly expanding the pool of known sources. Our main goal was to create a new, value-added catalogue of quasars with information about their extinction-corrected magnitudes, radio flux density, possible contamination levels, and other data flags, besides their sky coordinates and photometric redshifts. We cross-matched the optical Quaia catalogue of about 1.3 million quasars (selected from the Gaia data set) with 1.9 million sources from the Very Large Array Sky Survey (VLASS) radio catalogue. We explored different thresholds for the matching radius, balancing the completeness and purity of the resulting Quaia-VLASS catalogue, and found that 1.5 arc seconds is a sufficient choice. Our main finding is that the radio-loud fraction of quasars is in good agreement with previous works (< 10%), and there is no significant large-scale pattern in radio-loudness across the sky. The exact estimate depends on the G-band magnitude limit, and we observed some weak trends with redshift and absolute optical magnitude, possibly indicating remnant systematic effects in our data sets. The cross-matched Quaia-VLASS catalogue with 43,650 sources is available to the public for future analyses. This latest census of QSOs with radio counterparts will facilitate further investigations of the dichotomy of radio-loud and radio-quiet quasars, and it may also support other lines of investigations using quasars in cosmology and astrophysics.

Cosmic rays (CRs) are fundamental to the chemistry and physics of star-forming regions, influencing molecular gas ionization, mediating interactions with interstellar magnetic fields, and regulating star formation from the diffuse interstellar medium to the creation of stellar cores. The electronic GeV component of CRs is expected to produce non-thermal synchrotron radiation detectable at radio frequencies, yet such emissions from Galactic star-forming regions remain elusive. This study reports the first statistical attempt to detect synchrotron emission at 144 MHz using the LOw Frequency ARray (LOFAR) in the nearby Perseus molecular cloud (300 pc). By median-stacking 353 prestellar and 132 protostellar cores from the Herschel Gould Belt Survey and using LOFAR Two-Meter Sky Survey (LoTSS) data (20" resolution), 18 protostellar and 5 prestellar radio candidates were initially identified. However, these were likely extragalactic contaminants within the Herschel catalog. Stacked analyses did not reveal significant radio counterparts for prestellar and protostellar cores, with upper limits of $5\, \mu$Jy beam$^{-1}$ and $8\, \mu$Jy beam$^{-1}$, respectively. Non-detections suggest strong extinction mechanisms like free-free absorption and the Razin-Tsytovich effect for protostellar cores. For prestellar cores, analytical magnetostatic-isothermal models constrain the maximum ordered magnetic-field strength to 100 $\mu$G. Future predictions suggest that Square Kilometre Array-Low (SKA-Low) arrays could detect this emission in 9 hours (AA*) or 4 hours (AA4), enabling more sensitive constraints on synchrotron radiation in star-forming cores.

Exoplanet detection surveys revealed the existence of numerous multi-planetary systems packed close to their stability limit. In this proceeding, we review the mechanism driving the instability of compact systems, originally published in Petit et al. (2020). Compact systems dynamics are dominated by the interactions between resonances involving triplets of planets. The complex network of three-planet mean motion resonances drives a slow chaotic semi-major axes diffusion, leading to a fast and destructive scattering phase. This model reproduces quantitatively the instability timescale found numerically. We can observe signpost of this process on exoplanet systems architecture. The critical spacing ensuring stability scales as the planet-to star mass ratio to the power 1/4. It explains why the Hill radius is not an adapted measure of dynamical compactness of exoplanet systems, particularly for terrestrial planets. We also provide some insight on the theoretical tools developed in the original work and how they can be of interest in other problems.

The fine structures of solar radio bursts reveal complex dynamics in the corona, yet the observed characteristics of these sub-second bursts are additionally complicated by radio wave scattering in the turbulent solar corona. We examine the impact of anisotropic turbulence in radio-wave propagation simulations with non-radial magnetic field structures in shaping the morphology, time-characteristics, and source position of fine structures. The apparent sources are found to move along the direction of the magnetic-field lines and not along the density gradient, whereas the major axis of the scattered source is perpendicular to the local magnetic field (the scattering anisotropy axis). Using a dipolar magnetic field structure of an active region, we reproduce observed radio fine structure source motion parallel to the solar limb associated with a coronal loop and provide a natural explanation for puzzling observations of solar radio burst position motions with LOFAR. Furthermore, the anisotropy aligned with a dipolar magnetic field causes the apparent source images to bifurcate into two distinct components, with characteristic sizes smaller than in unmagnetized media. The temporal broadening induced by scattering reduces the observed frequency drift rate of fine structures, depending on the contribution of scattering to the time profile. The findings underscore the role of magnetic field geometry and anisotropic scattering for the interpretation of solar radio bursts and highlight that anisotropic scattering produces more than a single source.

This work focuses on the ice features toward the binary protostellar system Ced 110 IRS 4A and 4B, and observed with JWST as part of the Early Release Science Ice Age collaboration. We aim to explore the JWST observations of the binary protostellar system Ced~110~IRS4A and IRS4B to unveil and quantify the ice inventories toward these sources. We compare the ice abundances with those found for the same molecular cloud. The analysis is performed by fitting or comparing laboratory infrared spectra of ices to the observations. Spectral fits are carried out with the ENIIGMA fitting tool that searches for the best fit. For Ced~110~IRS4B, we detected the major ice species H$_2$O, CO, CO$_2$ and NH$_3$. All species are found in a mixture except for CO and CO$_2$, which have both mixed and pure ice components. In the case of Ced~110~IRS4A, we detected the same major species as in Ced~110~IRS4B, as well as the following minor species CH$_4$, SO$_2$, CH$_3$OH, OCN$^-$, NH$_4^+$ and HCOOH. Tentative detection of N$_2$O ice (7.75~$\mu$m), forsterite dust (11.2~$\mu$m) and CH$_3^+$ gas emission (7.18~$\mu$m) in the primary source are also presented. Compared with the two lines of sight toward background stars in the Chameleon I molecular cloud, the protostar has similar ice abundances, except in the case of the ions that are higher in IRS4A. The clearest differences are the absence of the 7.2 and 7.4~$\mu$m absorption features due to HCOO$^-$ and icy complex organic molecules in IRS4A and evidence of thermal processing in both IRS4A and IRS4B as probed by the CO$_2$ ice features. We conclude that the binary protostellar system Ced~110~IRS4A and IRS4B has a large inventory of icy species. The similar ice abundances in comparison to the starless regions in the same molecular cloud suggest that the chemical conditions of the protostar were set at earlier stages in the molecular cloud.

The extreme temperature gradients from day- to nightside in the atmospheres of hot Jupiters generate fast winds in the form of equatorial jets or day-to-night flows. Observations of blue-shifted and red-shifted signals in the transmission and dayside spectra of WASP-189b have sparked discussions about the nature of winds on this planet. To investigate the structure of winds in the atmosphere of the ultra-hot Jupiter WASP-189b, we studied its dayside emission spectrum with CRIRES$^+$ in the spectral K band. We used the cross-correlation method to detect emission signals of CO and Fe, and employed a Bayesian framework to retrieve the atmospheric parameters relating to the temperature-pressure structure and chemistry. The retrieval incorporated a numerical model of the line profile influenced by various dynamic effects to determine the wind structure. The cross-correlation signals of CO and Fe showed a velocity offset of ~6km/s, which could be caused by a fast day-to-night wind in the atmosphere of WASP-189b. The atmospheric retrieval showed that the line profile of the observed spectra is best fitted by the presence of a day-to-night wind of 4.4km/s, while the retrieved equatorial jet velocity of 1.0km/s is consistent with the absence of such a jet. Such a wind pattern is consistent with the observed line broadening and can explain the majority of the velocity offset, while uncertainties in the ephemerides and the effects of a hot spot could also contribute to this offset. We further retrieved an inverted temperature-pressure profile and determined the C/O ratio and metallicity. We showed that red-shifts of a few km/s in the dayside spectra could be explained by day-to-night winds. Further studies combining transmission and dayside observations could advance our understanding of WASP-189b's atmospheric circulation by improving the uncertainties in the velocity offset and wind parameters.

The recently launched James Webb Space Telescope (JWST) is opening new observing windows on the distant universe. Among JWST's instruments, the Mid Infrared Instrument (MIRI) offers the unique capability of imaging observations at wavelengths $\lambda > 5\mu$m. This enables unique access to the rest frame near infra-red (NIR, $\lambda \ge 1$\mum) emission from galaxies at redshifts $z>4$ and the visual ($\lambda \gtrsim 5000$Å) rest frame for $z>9$. We here report on the guaranteed time observations (GTO) from the MIRI European Consortium, of the Hubble Ultra Deep Field (HUDF), forming the MIRI Deep Imaging Survey (MIDIS), consisting of an on source integration time of $\sim41$ hours in the MIRI/F560W (5.6 $\mu$m) filter. To our knowledge, this constitutes the longest single filter exposure obtained with JWST of an extragalactic field as yet.

We study the statistical properties of the anisotropy in the gravitational wave (GW) background originating from supermassive black hole (SMBH) binaries. We derive the distribution of the GW anisotropy power spectrum coefficients, $C_{l\geq1}/C_0$, in scenarios including environmental effects and eccentricities of the SMBH binaries. Although the mean of $C_{l\geq1}/C_0$ is the same for all multipoles, we show that their distributions vary, with the low $l$ distributions being the widest. We also find a strong correlation between spectral fluctuations and the anisotropy in the GW signal. We show that the GW anisotropy can break the degeneracy between the scenarios including environmental effects or eccentricity. In particular, we find that existing NANOGrav constraints on GW anisotropy begin to constrain SMBH scenarios with strong environmental effects.

Lopsided galaxies are late-type galaxies with a non-axisymmetric disc due to an uneven distribution of their stellar mass. Despite being a relatively common perturbation, several questions regarding its origin and the information that can be extracted from them about the evolutionary history of late-type galaxies. The advent of several large multi-band photometric surveys will allow us to statistically analyze this perturbation, with information that was not previously available. Given the strong correlation between lopsidedness and the structural properties of the galaxies, this paper aims to develop a method to automatically classify late-type galaxies between lopsided and symmetric. We seek to explore if an accurate classification can be obtain by only considering their internal properties, without additional information about the environment. We select 8000 late-type galaxies from TNG50. A Fourier decomposition of their stellar mass surface density is used to label galaxies as lopsided and symmetric. We trained a Random Forest classifier to rapidly and automatically identify this type of perturbations, exclusively using galaxies internal properties. We test different algorithms to deal with the imbalance of our data and select the most suitable approach based on the considered metrics. We show that our trained algorithm can provide a very accurate and rapid classification of lopsided galaxies. The excellent results obtained by our classifier strongly supports the hypothesis that lopsidedness is mainly a tracer of galaxies internal structures. We show that similar results can be obtained using observable quantities, readily obtainable from multi-bad photometric surveys. Our results show it allows a rapid and accurate classification of lopsided galaxies, allowing us to explore whether lopsidedness in present-day disc galaxies is connected to galaxies specific evolutionary histories.

We present a long-term strong correlation between millimeter (mm) radio and $\gamma$-ray emission in the flat-spectrum radio quasar (FSRQ) PKS 1424-418. The mm$-\gamma$-ray connection in blazars is generally thought to originate from the relativistic jet close to the central engine. We confirm a unique long-lasting mm$-\gamma$-ray correlation of PKS 1424-418 by using detailed correlation analyses and statistical tests, and we find its physical meaning in the source. We employed ~8.5 yr of (sub)mm and $\gamma$-ray light curves observed by ALMA and Fermi-LAT, respectively. From linear and cross-correlation analyses between the light curves, we found a significant, strong mm$-\gamma$-ray correlation over the whole period. We did not find any notable time delay within the uncertainties for the mm$-\gamma$-ray correlation, which means zero lag. The mm wave spectral index values (S$_{\nu}$ $\propto$ $\nu_{\alpha}$) between the band 3 and 7 flux densities indicate a time-variable opacity of the source at (sub)mm wavelengths. Interestingly, the mm wave spectral index becomes temporarily flatter (i.e., $\alpha$ > $-$0.5) when the source flares in the $\gamma$-rays. We relate our results with the jet of PKS 1424-418, and we discuss the origin of the $\gamma$-rays and opacity of the inner (sub)parsec-scale jet regions.

Disk winds play a crucial role in the evolution of protoplanetary disks. Typical conditions for star and planet formation are in regions with intermediate or strong UV radiation fields produced by massive stars. The $\sigma$-Orionis cluster is the ideal site to study disk winds under these conditions; its outer parts can be used to study disk evolution, while its innermost regions to study the effect of external irradiation. For this, we analyze the $\rm [OI]\,\lambda$6300, $\rm [NII]\,\lambda$6583, and $\rm [SII]\,\lambda$6731,$\lambda$6716 lines using high-resolution MIKE spectra of 27 classical T Tauri stars and complemented by intermediate-resolution X-shooter data. We decompose the line profiles into multiple Gaussian components. We calculated luminosities, line ratios, and kinematic properties of these components. We found that the $\rm [OI]\,\lambda$6300 line luminosity and kinematic properties are similar to those found in low-mass star-forming regions (SFRs). The frequency of single-component $\rm [OI]\,\lambda$6300 line profiles reflects the expected evolutionary stage given the intermediate age of $\sigma$-Orionis. This points to internal processes contributing to the line emission. However, the highly irradiated disks do not follow the accretion - [OI] luminosity relation found in low-mass SFRs, and all exhibit single-component line profiles. Line ratios of highly ionized species of [NII] and [SII] show higher ratios than typical values found in low-mass SFRs. The innermost regions of $\sigma$-Orionis are clearly affected by external irradiation, evidenced by the lack of correlation in the accretion - [OI] luminosity relation. The broad line widths of close-in sources, however, indicate a contribution from internal processes, such as magnetohydrodynamical winds and/or internal photoevaporation. This suggests a coevolution of internal and external winds in $\sigma$-Orionis.

The presence of a hydrosphere on Europa raises questions about its habitability, and studies of its volatile inventory can provide insight into its formation process. Different scenarios suggest that Europa's volatiles could be derived from cometary ices or devolatilized building blocks. The study of post-accretion processes, in particular the "open ocean" phase that likely occurred before the formation of the icy crust, is crucial to distinguish these origins, as this phase is likely to have influenced the volatile inventory. The abundance of ammonia in Europa's building blocks is also crucial for understanding the composition of its ocean and primordial atmosphere. We aim to investigate ocean-atmosphere equilibrium during the post-accretion period by varying the ammonia fraction in the atmosphere. Our model evaluates the vapor-liquid equilibrium of water and volatiles, as well as the chemical equilibrium within the ocean, to study Europa's early hydrosphere. We explore two initial conditions: one in which Europa's hydrosphere originates from comet-like building blocks, and another in which it forms in equilibrium with a thick, CO$_2$-rich atmosphere. In both scenarios, the initial ratio of accreted CO$_2$ to NH$_3$ determines the magnitude of their partial pressures in Europa's early atmosphere. If this ratio exceeds a certain threshold (set to $10^{-4}$ in this study), the atmosphere will be CO$_2$-rich; otherwise, it will be CO$_2$-depleted by multiple orders of magnitude. Overall, our work provides a initial assessment of the distribution of primordial volatiles in Europa's primitive hydrosphere, and provides a baseline for interpreting data from the upcoming Europa Clipper mission.

Gamma-ray bursts (GRBs) are usually classified into long/short categories according to their durations, but controversy still exists in this aspect. Here we re-examine the long/short classification of GRBs and further compare the cosmological distribution and evolution of each potential subclass. A large number of $Swift/BAT$ GRBs are analyzed in this study. The Gaussian mixture model is used to fit the duration distribution as well as the joint distribution of duration and hardness ratio, and the Akaike and Bayesian information criteria are adopted to assess the goodness of fit. It is found that three Gaussian components can better fit both the univariate and bivariate distributions, indicating that there are three subclasses in the $Swift/BAT$ GRBs, namely short, intermediate, and long subclasses. The non-parametric Efron-Petrosian and Lynden-Bell's $c^{-}$ methods are used to derive the luminosity function and formation rate from the truncated data of bursts with known redshift in each subclass. It is found that the luminosity distributions and birth rates of the three subclasses are different, further supporting the existence of the intermediate subclass in the $Swift/BAT$ GRBs.

The Atacama Millimeter/Submillimeter Array (ALMA) remains unparalleled in sensitivity at radio frequencies above 35 GHz. In this paper, we explore ALMA's potential for narrowband technosignature detection, considering factors such as the interferometer's undistorted field of view, signal dilution due to significant drift rates at high frequencies and the possibility of spectral confusion. We present the first technosignature survey using archival ALMA data in Band 3, focusing on two spectral windows centred on 90.642 GHz and 93.151 GHz. Our survey places new limits at these frequencies on the prevalence of extraterrestrial transmitters for 28 galactic stars, selected from the Gaia DR3 catalogue. We employ a stellar 'bycatch' method to sample these objects within the undistorted field of view of four ALMA calibrators. For the closest star in our sample, we find no evidence of transmitters with EIRP_min > 7 x 10^17 W. To the best of our knowledge, this represents the first technosignature search conducted using ALMA data.

The stability of toroidal magnetic fields within the interior of stars remains a significant unresolved issue in contemporary astrophysics. In this study, we combine a nonlocal linear analysis with 3D direct numerical simulations to examine the instability of toroidal fields within nonrotating, stably stratified stellar interiors in spherical geometry. Both analyses start from an equilibrium solution derived from balancing the Lorentz force with an anisotropic component of the fluid pressure, which is unstable to the (nonaxisymmetric) Tayler instability, and account for the combined effects of gravity and thermal diffusion. The numerical simulations incorporate finite magnetic resistivity and fluid viscosity while reaching a regime of highly stable stratification that has never been explored before. The linear analysis, which is global in the radial direction, shows that gravity significantly reduces the growth rate of the instability and uncovers the importance of unstable modes with low radial wavenumbers operating at low latitudes. The simulations trace the entire evolution of the instability from the linear to the nonlinear phase and strongly corroborate the findings of the linear analysis. Our results reveal that in highly stratified stellar interiors, the newly configured magnetic fields remain unstable only on the thermal diffusion timescale. Combining the linear analysis results with stellar evolution models of low-mass stars, we find that the limiting toroidal field strength for Tayler instability in red giant cores decreases with the stellar evolution. The predicted field strengths align with the ones expected from recent asteroseismic observations, suggesting that the observed fields may be remnants of a Tayler instability during the transition from the main sequence to the giant phase.

We study an extension of the natural inflation model comprising a non-Abelian gauge sector coupled to the axion-inflaton kinetic term. We show how such non-minimal coupling serves as a source of friction for the rolling inflaton granting sixty or more $e$-folds of accelerated expansion for sub-Planckian values of the axion decay constant. The analysis of perturbations reveals a negative sound speed, thus signaling an instability. Implementing a Chern-Simons-type coupling between the inflaton and gauge sectors cures the instability by delivering a positive speed. We perform a numerical study of scalar and tensor perturbations for a fiducial set of parameters finding that the corresponding observables are compatible with current CMB bounds.

We investigate UV continuum slopes $\beta$ of 974 galaxies at $z=4-14$ using archival JWST/NIRSpec PRISM spectra obtained from major JWST GTO, ERS, and GO programs, including JADES, CEERS, and UNCOVER. Among these galaxies, we identify a remarkable galaxy at $z=9.25$, dubbed EBG-1, with a significantly blue UV slope $\beta=-2.99\pm0.15$, unlike the rest of the galaxies that exhibit red continua or ambiguous blue continua hindered by large uncertainties. We confirm that the $\beta$ value negligibly changes by the data reduction and fitting wavelength ranges for UV emission/absorption line masking. The extreme blue slope, $\beta=-3.0$, rules out significant contributions from dust extinction or AGN activity. Comparing with stellar and nebular emission models, we find that such a blue UV slope cannot be reproduced solely by stellar models even with very young, metal-poor, or top-heavy contiguous star formation associated with strong nebular continua making the UV slopes red, but with a high ionizing photon escape fraction, $f_\mathrm{esc}^\mathrm{ion} \gtrsim 0.5$, for a weak nebular continuum. While the H$\beta$ emission line is not detected, likely due to the limited sensitivity of the spectrum, we find moderately weak [O III] $\lambda\lambda$4959,5007 emission lines for the given star-formation rate ($3\, \mathrm{M_\odot}$ yr$^{-1}$) and stellar mass ($10^{8.0} \, \mathrm{M_\odot}$) that are about three times weaker than the average emission lines, again suggestive of the high ionizing photon escape fraction, $f_\mathrm{esc}^\mathrm{ion} \sim 0.7$ or more. EBG-1 would provide crucial insights into stellar and nebular continuum emission in high-redshift galaxies, serving as an example of the ionizing photon escaping site at the epoch of reionization.

We use galaxy cluster abundance measurements from the South Pole Telescope (SPT) enhanced by Multi-Component Matched Filter (MCMF) confirmation and complemented with mass information obtained using weak-lensing data from Dark Energy Survey Year~3 (DES Y3) and targeted Hubble Space Telescope (HST) observations for probing deviations from the cold dark matter paradigm. Concretely, we consider a class of dark sector models featuring interactions between dark matter (DM) and a dark radiation (DR) component within the framework of the Effective Theory of Structure Formation (ETHOS). We focus on scenarios that lead to power suppression over a wide range of scales, and thus can be tested with data sensitive to large scales, as realized for example for DM$-$DR interactions following from an unbroken non-Abelian $SU(N)$ gauge theory (interaction rate with power-law index $n=0$ within the ETHOS parameterization). Cluster abundance measurements are mostly sensitive to the amount of DR interacting with DM, parameterized by the ratio of DR temperature to the cosmic microwave background (CMB) temperature, $\xi_{\rm DR}=T_{\rm DR}/T_{\rm CMB}$. We find an upper limit $\xi_{\rm DR}<17\%$ at $95\%$ credibility. When the cluster data are combined with Planck 2018 CMB data along with baryon acoustic oscillation (BAO) measurements we find $\xi_{\rm DR}<10\%$, corresponding to a limit on the abundance of interacting DR that is around three times tighter than that from CMB+BAO data alone. We also discuss the complementarity of weak lensing informed cluster abundance studies with probes sensitive to smaller scales, explore the impact on our analysis of massive neutrinos, and comment on a slight preference for the presence of a non-zero interacting DR abundance, which enables a physical solution to the $S_8$ tension.

Type Ia supernovae, critical for studying cosmic expansion, arise from thermonuclear explosions of white dwarfs, but their precise progenitor pathways remain unclear. Growing evidence supports the ``double-degenerate'' scenario, where two white dwarfs interact. The absence of other companion types capable of explaining the observed Ia rate, along with observations of hyper-velocity white dwarfs interpreted as surviving companions of such systems provide compelling evidence in favor of this scenario. Upcoming millihertz gravitational wave observatories like the Laser Interferometer Space Antenna (LISA) are expected to detect thousands of double-degenerate systems, though the most compact known candidate Ia progenitors produce only marginally detectable gravitational wave signals. Here, we report observations of ATLAS J1138-5139, a binary white dwarf system with an orbital period of 28 minutes. Our analysis reveals a 1 solar mass carbon-oxygen white dwarf accreting from a helium-core white dwarf. Given its mass, the accreting carbon-oxygen white dwarf is poised to trigger a typical-luminosity Type Ia supernova within a few million years, or to evolve into a stably mass-transferring AM CVn system. ATLAS J1138-5139 provides a rare opportunity to calibrate binary evolution models by directly comparing observed orbital parameters and mass transfer rates closer to merger than any previously identified candidate Type Ia progenitor. Its compact orbit ensures detectability by LISA, demonstrating the potential of millihertz gravitational wave observatories to reveal a population of Type Ia progenitors on a Galactic scale, paving the way for multi-messenger studies offering insights into the origins of these cosmologically significant explosions.

We present a new scale decomposition method to investigate turbulence in wavenumber-frequency space. Using 3D magnetohydrodynamic turbulence simulations, we show that magnetic fluctuations with time scales longer than the nonlinear time exhibit an inverse cascade toward even smaller frequencies. Low frequency magnetic fluctuations support turbulence, acting as an energy reservoir that is converted into plasma kinetic energy, the latter cascading toward large wavenumbers and frequencies, where it is dissipated. Our results shed new light on the spatio-temporal properties of turbulence, potentially explaining the origin and role of low frequency turbulent fluctuations in the solar wind.

Presolar grains are stardust particles that condensed in the ejecta or in the outflows of dying stars and can today be extracted from meteorites. They recorded the nucleosynthetic fingerprint of their parent stars and thus serve as valuable probes of these astrophysical sites. The most common types of presolar silicon carbide grains (called mainstream SiC grains) condensed in the outflows of asymptotic giant branch stars. Their measured silicon isotopic abundances are not significantly influenced by nucleosynthesis within the parent star, but rather represents the pristine stellar composition. Silicon isotopes can thus be used as a proxy for galactic chemical evolution. However, the measured correlation of $^{29}$Si/$^{28}$Si versus $^{30}$Si/$^{28}$Si does not agree with any current chemical evolution model. Here, we use a Monte Carlo model to vary nuclear reaction rates within their theoretical or experimental uncertainties and process them through stellar nucleosynthesis and galactic chemical evolution models to study the variation of silicon isotope abundances based on these nuclear reaction rate uncertainties. We find that these uncertainties can indeed be responsible for the discrepancy between measurements and models and that the slope of the silicon isotope correlation line measured in mainstream SiC grains agrees with chemical evolution models within the nuclear reaction rate uncertainties. Our result highlights the importance of future precision reaction rate measurements for resolving the apparent data-model discrepancy.

We present an analysis of two epochs of ACIS observations of the SA(s)c spiral galaxy NGC 3938 with the Chandra X-ray Observatory. The total exposure time of the observations was 95 ksec with a limiting unabsorbed luminosity of approximately 10^{38}$ ergs/sec assuming a distance of 22 Mpc. A total of 47 discrete merged sources from both epochs were detected at the 3sigma level or greater with the D25 radius. We demonstrate that at the time of the Chandra observations, the nucleus was not detected. We connect the detected sources to counterparts in other wavebands to the degree possible. Based on the two epochs, we identify three variable sources and an additional two that may have varied between the two observations. We do not formally detect any of the five historical supernovae that have occurred in NGC 3938. The luminosity function of NGC 3938 is compared to a recent compilation of 38 galaxies and we identify a potentially significant problem with the `known' distance to NGC 3938. Star formation rate and metallicity values are also computed; the star formation rate is highly dependent upon the adopted distance. The metallicity appears to lie in the range of 8.2-9.2, consistent with values from other work. We include in an appendix a short discussion of the sources that lie in Chandra's field-of-view but lie outside of NGC 3938.

The circumgalactic medium (CGM), as the gas repository for star formation, might contain the answer to the mysterious galaxy quenching and bimodal galaxy population origin. We measured the X-ray emission of the hot CGM around star-forming and quiescent galaxies. We detect extended X-ray emission from the hot CGM around star-forming galaxies with $\log(M_*/M_\odot)>11.0$ and quiescent galaxies with $\log(M_*/M_\odot)>10.5$, extending out to $R_{\rm 500c}$. $L_{\rm X, CGM}$ of star-forming galaxies with median stellar masses $\log(M_{\rm *,med}/M_\odot) = 10.7, 11.1, 11.3$ are approximately $0.8\,, 2.3\,, 4.0 \times 10^{40}\,\rm erg/s$, while for quiescent galaxies with $\log(M_{\rm *,med}/M_\odot) = 10.8, 11.1, 11.4$, they are $1.1\,, 6.2\,, 30 \times 10^{40}\,\rm erg/s$. Notably, quiescent galaxies with $\log(M_{\rm *,med}/M_\odot) > 11.0$ exhibit brighter hot CGM than their star-forming counterparts. In halo mass bins, we detect similar X-ray emission around star-forming and quiescent galaxies with $\log(M_{\rm 200m}/M_\odot) > 12.5$, suggesting that galaxies in the same mass dark matter halos host equally bright hot CGM. We emphasize the observed $L_{\rm X, CGM} - M_{\rm 500c}$ relations of star-forming and quiescent galaxies are sensitive to the stellar-to-halo mass relation (SHMR). A comparison with cosmological hydrodynamical simulations (EAGLE, TNG100, and SIMBA) reveals varying degrees of agreement, contingent on the simulation and the specific stellar or halo mass ranges considered. Either selected in stellar mass or halo mass, the star-forming galaxies do not host brighter stacked X-ray emission from the hot CGM than their quiescent counterparts at the same mass range. The result provides useful constraints on the extent of feedback's impacts as a mechanism for quenching star formation as implemented in current cosmological simulations.

This paper investigates the influence of nonlinear dissipative forces, specifically Gravitational Friction (GF), on the precession of celestial bodies within the framework of general relativity. We derive a modified line element by introducing a density-dependent term to model interactions between planetary bodies and the low-density interplanetary medium, providing a covariant description of dissipative forces in planetary motion. The resulting metric modification leads to corrections in the perihelion precession of Mercury, also reproducing the classical relativistic predictions. Utilizing the method of multiple scales, we analyze perturbative effects induced by GF. Using this model, we successfully constrain the medium density near Mercury to approximately $\rho_0 \approx 1.12 \times 10^{-10} \, \text{kg/m}^3$. These findings offer a new approach for incorporating dissipative mechanisms into general relativity, with potential applications in other astrophysical systems.

GPU is the dominant accelerator device due to its high performance and energy efficiency. Directive-based GPU offloading using OpenACC or OpenMP target is a convenient way to port existing codes originally developed for multicore CPUs. Although OpenACC and OpenMP target provide similar features, both methods have pros and cons. OpenACC has better functions and an abundance of documents, but it is virtually for NVIDIA GPUs. OpenMP target supports NVIDIA/AMD/Intel GPUs but has fewer functions than OpenACC. Here, we have developed a header-only library, Solomon (Simple Off-LOading Macros Orchestrating multiple Notations), to unify the interface for GPU offloading with the support of both OpenACC and OpenMP target. Solomon provides three types of notations to reduce users' implementation and learning costs: intuitive notation for beginners and OpenACC/OpenMP-like notations for experienced developers. This manuscript denotes Solomon's implementation and usage and demonstrates the GPU-offloading in $N$-body simulation and the three-dimensional diffusion equation. The library and sample codes are provided as open-source software and publicly and freely available at \url{this https URL}.

Based on the relativistic mean field (RMF) model with Thomas-Fermi approximation, we investigate the elastic properties of neutron star matter. The elastic constants are estimated by introducing deformations on the nuclear pasta structures in $\beta$-equilibrium, where various crystalline configurations are considered in a fully three-dimensional geometry without the Wigner-Seitz approximation. Two scenarios with different symmetry energy slope ($L = 41.34$ and 89.39 MeV) are examined, where the the elastic constants can vary by ten times. By fitting to the numerical results, we improve the analytic formulae for the elastic properties of nuclear pasta by introducing damping factors.

Gravitational waves, first predicted by Albert Einstein within the framework of general relativity, were confirmed in 2015 by the LIGO/Virgo collaboration, marking a pivotal breakthrough in astrophysics. Despite this achievement, a key challenge remains in distinguishing true gravitational wave signals from noise artifacts, or "glitches," which can distort data and affect the quality of observations. Current state-of-the-art methods, such as the Q-transform, are widely used for signal processing, but face limitations when addressing certain types of signals. In this study, we investigate the Wavelet Scattering Transform (WST), a recent signal analysis method, as a complementary approach. Theoretical motivation for WST arises from its stability under signal deformations and its equivariance properties, which make it particularly suited for the complex nature of gravitational wave data. Our experiments on the LIGO O1a dataset show that WST simplifies classification tasks and enables the use of more efficient architectures compared to traditional methods. Furthermore, we explore the potential benefits of integrating WST with the Q-transform, demonstrating that ensemble methods exploiting both techniques can capture complementary features of the signal and improve overall performance. This work contributes to advancing machine learning applications in gravitational wave analysis, introducing refined preprocessing techniques that improve signal detection and classification.

In metric-affine gravity, both the gravitational and matter actions depend not just on the metric, but also on the independent affine connection. Thus matter can be modeled as a hyperfluid, characterized by both the energy-momentum and hypermomentum tensors. The latter is defined as the variation of the matter action with respect to the connection and it encodes extra (micro)properties of particles. For a homogeneous and isotropic universe, it was recently shown that the generic cosmological hypermomentum possesses five degrees of freedom: one in dilation, two in shear, and two in spin part. The aim of the current work is to present the first systematic study of the implications of this perfect hyperfluid on the universe with Friedmann-Lemaître-Robertson-Walker metric. We adopt a simple model with non-Riemannian Einstein-Hilbert gravitational action plus arbitrary hyperfluid matter, and solve analytically the cosmological equations for single and multiple component hypermomentum contributions using different assumptions about the equation of state. It is remarkable, that in a number of cases the forms of the time evolution of the Hubble function and energy density still coincide with their general relativity counterparts, only the respective indexes $\mathrm{w}_{\mathrm{eff}}$ and $\mathrm{w}_\rho$ start to differ due to the hypermomentum corrections. The results and insights we obtained are very general and can assist in constructing interesting models to resolve the issues in standard cosmology.

One of the main goals of gravitational-wave astrophysics is to study gravity in the strong-field regime and constrain deviations from general relativity. Any such deviation affects not only binary dynamics and gravitational-wave emission but also the structure and tidal properties of compact objects. In the case of neutron stars, masses, radii, and tidal deformabilities can all differ significantly between different theories of gravity. Currently, the measurement uncertainties in neutron-star radii and tidal deformabilities are quite large. However, much less is known about how the large uncertainty in the nuclear equation of state might affect tests of general relativity using binary neutron-star mergers. Conversely, using the wrong theory of gravity might lead to incorrect constraints on the nuclear equation of state. Here we study this problem within scalar-tensor theory. We apply the recently derived $\ell = 2$ tidal love numbers in this theory to parameter estimation of GW170817. Correspondingly, we test if physics beyond general relativity could bias measurements of the nuclear equation of state and neutron-star radii. We find that parameter inference for both the general relativistic and scalar-tensor case return consistent component masses and tidal deformabilites. The radius and the equation of state posteriors, however, differ between the two theories, but neither is excluded by current observational limits. This indicates that measurements of the nuclear equation of state may be biased and that deviations from general relativity could go undetected when analyzing current binary neutron star mergers.

We present and explore a new shock-capturing particle hydrodynamics approach. We enhance a commonly used SPH discretization with Roe's approximate Riemann solver where we use slope-limited linear reconstruction in the dissipative terms of the solver. All gradients of the method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest order consistency relations so that constant and linear functions can be recovered to machine precision. We scrutinize the method with a set of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity creating shocks. In all of them we find excellent agreement with analytic/reference solutions.

Gravitational waves (GW), predicted by Einstein's General Theory of Relativity, provide a powerful probe of astrophysical phenomena and fundamental physics. In this work, we propose an unsupervised anomaly detection method using variational autoencoders (VAEs) to analyze GW time-series data. By training on noise-only data, the VAE accurately reconstructs noise inputs while failing to reconstruct anomalies, such as GW signals, which results in measurable spikes in the reconstruction error. The method was applied to data from the LIGO H1 and L1 detectors. Evaluation on testing datasets containing both noise and GW events demonstrated reliable detection, achieving an area under the ROC curve (AUC) of 0.89. This study introduces VAEs as a robust, unsupervised approach for identifying anomalies in GW data, which offers a scalable framework for detecting known and potentially new phenomena in physics.

Galaxy morphology analysis involves classifying galaxies by their shapes and structures. For this task, directly training domain-specific models on large, annotated astronomical datasets is effective but costly. In contrast, fine-tuning vision foundation models on a smaller set of astronomical images is more resource-efficient but generally results in lower accuracy. To harness the benefits of both approaches and address their shortcomings, we propose GalaxAlign, a novel method that fine-tunes pre-trained foundation models to achieve high accuracy on astronomical tasks. Specifically, our method extends a contrastive learning architecture to align three types of data in fine-tuning: (1) a set of schematic symbols representing galaxy shapes and structures, (2) textual labels of these symbols, and (3) galaxy images. This way, GalaxAlign not only eliminates the need for expensive pretraining but also enhances the effectiveness of fine-tuning. Extensive experiments on galaxy classification and similarity search demonstrate that our method effectively fine-tunes general pre-trained models for astronomical tasks by incorporating domain-specific multi-modal knowledge.

We present a method for solving loop integrals in dimensional regularization that is particularly useful in the context of inflation. We apply this method to the calculation of the tensor power spectrum induced by scalar fluctuations in slow-roll inflation.

Stochastic background gravitational waves have not yet been detected by ground-based laser interferometric detectors, but recent improvements in detector sensitivity have raised considerable expectations for their eventual detection. Previous studies have introduced methods for exploring anisotropic background gravitational waves using Bayesian statistics. These studies represent a groundbreaking approach by offering physically motivated anisotropy mapping that is distinct from the Singular Value Decomposition regularization of the Fisher Information Matrix. However, they are limited by the use of a single model, which can introduce potential bias when dealing with complex data that may consist of a mixture of multiple models. Here, we demonstrate the bias introduced by a single-component model approach in the parametric interpretation of anisotropic stochastic gravitational-wave backgrounds, and we confirm that using multiple-component models can mitigate this bias.

The indirect detection of dark matter (DM) through its annihilation products is one of the primary strategies for DM detection. One of the least constrained classes of models is neutrinophilic DM, because the annihilation products, weakly interacting neutrinos, are challenging to observe. Here, we consider a scenario where MeV-mass DM exclusively annihilates to the third neutrino mass eigenstate, which is predominantly of tau and muon flavor. In such a scenario, the potential detection rate of the neutrinos originating from the DM annihilation in our galaxy in the conventional detectors would be suppressed by up to approximately two orders of magnitude. This is because the best sensitivity of such detectors for neutrinos with energies below approximately 100~MeV is for electron neutrino flavor. In this work, we highlight the potential of large-scale DM detectors in uncovering such signals in the tens of MeV range of DM masses. In addition, we discuss how coincident signals in direct detection DM experiments and upcoming neutrino detectors such as DUNE, Hyper-Kamiokande, and JUNO could provide new perspectives on the DM problem.

We consider evolving, spatially flat isotropic and homogeneous (FLRW) cosmologies in ghost-free (dRGT) massive gravity. In this theory, no dynamical flat FLRW background exists if the reference metric is chosen to be Minkowski and the Stueckelberg fields are homogeneous. Relaxing the assumptions on the Stueckelberg profiles gives access to dynamical backgrounds. We propose a classification of the viable flat FLRW cosmological solutions of dRGT massive gravity. Instead of specifying an initial ansatz for the Stueckelberg fields $\phi^a$ and the reference metric $f_{ab}$, we show that imposing homogeneity and isotropy on the square root tensor $X^{\mu}_{\nu}=\left(\sqrt{g^{-1}\partial\phi^a \partial\phi^bf_{ab}}\right)^{\mu}_{\nu}$ leads to dynamical cosmological solutions, and we characterize their properties. These solutions become dynamical only when the Stueckelberg fields acquire a sufficiently inhomogeneous and/or anisotropic profile. We explore the consequences for the minimal model and the complete dRGT theory, and show that perturbations are strongly coupled, at the quadratic level, on these backgrounds.