Vote on papers for Wednesday, Sep 03 2025

This white paper is a summary of the Uranus Flagship Workshop that took place 21 to 23 May 2024 at NASA's Goddard Space Flight Center. Co-led by Goddard and Johns Hopkins Applied Physics Lab conveners, we had a broad, international, Science Organizing Committee, and a largely early career Local Organizing Committee from APL and GSFC. From prior workshops, it was apparent that the community was wildly enthusiastic about starting a mission, but lacked focus on what was possible or where to begin. Thus, the purpose of our workshop was to discuss practical aspects of the next planetary flagship and how we can employ new paradigms to better enable robust outer planet exploration. To enable this goal, we introduced the community to the best practices and lessons learned from previous missions and NASA-commissioned studies, and discussed the challenges involved with a mission so far from the Earth/Sun. The underlying workshop purpose was to steward the community towards a more practical mission design approach that will enable the development of this mission, as well as future missions, on a shorter cadence by setting expectations and having difficult discussions early in development. Because of the time scales involved in this mission, special effort was made towards early career inclusion and participation.

The presence of massive black holes (BHs) exceeding $10^9\,{\rm M}_{\odot}$ already at redshift $z > 6$ challenges standard models of BH growth. Super-Eddington (SE) accretion has emerged as a promising mechanism to solve this issue, yet its impact on early BH evolution in tailored numerical experiments remains largely unexplored. In this work, we investigate the growth of BH seeds embedded in a gas-rich, metal-poor protogalaxy at $z \sim 15$, using a suite of high-resolution hydrodynamical simulations that implement a slim-disc-based SE accretion model. We explore a broad parameter space varying the initial BH mass, feedback efficiency, and spin. We find that SE accretion enables rapid growth in all cases, allowing BHs to accrete up to $10^5\,{\rm M}_{\odot}$ within a few $10^3$-$10^4$ years, independent of seed properties. Feedback regulates this process, both by depleting central gas and altering BH dynamics via star formation-driven potential fluctuations, yet even the strongest feedback regimes permit significantly greater growth than the Eddington-limited case. Growth stalls after less than $\sim$1 Myr due to local gas exhaustion, as no large-scale inflows are present in the adopted numerical setup. Our results show that SE accretion naturally leads to BHs that are over-massive relative to their host galaxy stellar content, consistent with JWST observations. We conclude that short, low-duty-cycle SE episodes represent a viable pathway for assembling the most massive BHs observed at early cosmic times, even starting from light seeds.

We present a grid of rotating supergiant models from post-main sequence binary merger products, constructed by the MESA stellar evolution code. We focus on the evolution of these stars until core-collapse, in addition to their rotation, which could influence their mass loss and explosion phenomenology. We find that (i) as in previous studies, larger mass gain by merger favors the production of blue supergiants (BSGs) over red supergiants, and (ii) merger products that end as BSGs at core collapse have rotating outer envelopes, with lower-mass BSGs having faster envelope rotation due to less wind mass loss. We model the expected transients from these BSGs upon core-collapse, considering cases where the neutrino-driven explosion is successful and unsuccessful. The successful explosions result in supernovae (SNe) with long-rising light curves of morphology similar to SN 1987A. Failed explosions of these BSGs result in envelope fallback of $\sim (0.1$- several) $~M_\odot$ over $10^3$-$10^5$ seconds that power strong ($10^{51}$-$10^{53}$ erg) accretion-driven outflows in winds and possibly jets, with relativistic jets (if formed) generally capable of breaking out of the BSG envelope. Our modeling points to these merger-origin BSGs as viable progenitors for SN 1987A-like SNe, ultra-long gamma-ray bursts, and some of the fast luminous transients found in high-cadence optical surveys.

We have employed deep far-UV observations secured with the Solar Blind Channel of the Advanced Camera for Surveys onboard the Hubble Space Telescope to search for hot companions to five blue stragglers stars (BSSs) showing significant surface depletion of carbon (C) and oxygen (O), in the Galactic globular cluster 47 Tucanae. Such a chemical pattern has been interpreted as the chemical signature of the mass transfer formation process for the observed blue stragglers. The mass transfer origin is also expected to leave a "photometric signature" in the form of a UV-excess, as the stripped core of the donor star should be observable as a white dwarf (WD) companion orbiting the newborn BSS. We found strong evidence for the presence of a hot (T > 20000 K) WD companion to one of the investigated BSS, indicating that it likely formed through mass transfer less than 12 Myr ago. This is the first simultaneous evidence of the chemical and the photometric signatures of the mass-transfer formation channel. The lack of evidence for a hot companion to the other investigated blue stragglers is consistent with the expectation that the photometric signature (as well as the chemical one) is a transient phenomenon.

We present the COLIBRE galaxy formation model and the COLIBRE suite of cosmological hydrodynamical simulations. COLIBRE includes new models for radiative cooling, dust grains, star formation, stellar mass loss, turbulent diffusion, pre-supernova stellar feedback, supernova feedback, supermassive black holes and active galactic nucleus (AGN) feedback. The multiphase interstellar medium is explicitly modelled without a pressure floor. Hydrogen and helium are tracked in non-equilibrium, with their contributions to the free electron density included in metal-line cooling calculations. The chemical network is coupled to a dust model that tracks three grain species and two grain sizes. In addition to the fiducial thermally-driven AGN feedback, a subset of simulations uses black hole spin-dependent hybrid jet/thermal AGN feedback. To suppress spurious transfer of energy from dark matter to stars, dark matter is supersampled by a factor 4, yielding similar dark matter and baryonic particle masses. The subgrid feedback model is calibrated to match the observed $z \approx 0$ galaxy stellar mass function, galaxy sizes, and black hole masses in massive galaxies. The COLIBRE suite includes three resolutions, with particle masses of $\sim 10^5$, $10^6$, and $10^7\,\text{M}_\odot$ in cubic volumes of up to 50, 200, and 400 cMpc on a side, respectively. The two largest runs use 136 billion ($5 \times 3008^3$) particles. We describe the model, assess its strengths and limitations, and present both visual impressions and quantitative results. Comparisons with various low-redshift galaxy observations generally show very good numerical convergence and excellent agreement with the data.

Recent pulsar timing array (PTA) analyses show evidence for a gravitational wave background (GWB) with angular correlations consistent with the Hellings-Downs curve. Anisotropies are a key discriminator of the origin of this GWB, as they are expected to be at 1--20\% for astrophysical sources, but suppressed for cosmological GWBs. However, contrary to gravitational wave detectors at higher frequencies, PTAs only take a few independent measurements of a GWB and consequently are highly sensitive to cosmic variance, which induces apparent anisotropies in individual realizations of an isotropic GWB. We demonstrate explicitly that statistical inference nevertheless remains robust, i.e., measurements are consistent with the underlying assumption of isotropy. This confirms that searches for anisotropies will be able to robustly discriminate astrophysical from cosmological GWBs. En route, we demonstrate that the maximum multipole constrained by a PTA dataset scales linearly with the number of pulsars $\ell_{\rm max} \sim N_p$.

We investigate the impacts of the evolution of dust mass and grain size distribution within a Milky Way-like (MW-like) galaxy simulation on global attenuation curves, focusing on the optical-UV slope and the 2175 $AA$ bump. We discuss the contributions of star-dust geometry, scattering, and dust properties. Post-processing dust radiative transfer was performed using SKIRT based on the MW-like galaxy simulation. The simulation was carried out with GADGET4-OSAKA, which models the evolution of grain size distributions. For lower inclination angles (closer to face-on), the attenuation curve flattens over time up to t=1 Gyr, then becomes progressively steeper. This steeper slope arises from the interplay between scattering and the dust disk becoming more extended over time (changes in star-dust geometry). At higher inclination, scattering is suppressed, and the attenuation curves slightly steepen over time due to small-grain formation and the bias of observed UV light toward older stars. The bump strengthens on a timescale of ~250 Myr due to the formation of small carbonaceous grains. The bump strength is affected not only by the abundance of small grains but also by star-dust geometry. At higher $A_V$ or higher inclination, the bump weakens. These results may help interpret flatter attenuation curves and weaker bumps in high-redshift galaxies. Variations in star-dust geometry alter the amount of scattered photons escaping the galaxy, driving the anti-correlation between the slope and $A_V$. Scatter in this relation arises from differences in dust optical depth along and perpendicular to the line of sight, reflecting inclination and star-dust geometry. Additional contributions come from variations in grain size distribution and the fraction of obscured young stars.

Photoevaporative models predict that the lower edge of the Neptune desert is sculpted by atmospheric mass loss. However, the stellar high energy fluxes that power hydrodynamic escape and set predicted mass loss rates can be uncertain by multiple orders of magnitude. These uncertainties can be bypassed by studying mass loss for planets within the same system, as they have effectively undergone scaled versions of the same irradiation history. The TOI-4010 system is an ideal test case for mass loss models, as it contains three Neptune-sized planets with planet b located in the `Neptune desert', planet c in the `Neptune ridge', and planet d in the `Neptune savanna'. Using Keck/NIRSPEC, we measured the metastable helium transit depths of all three planets in order to search for evidence of atmospheric escape. We place upper bounds on the excess helium absorption of 1.23\%, 0.81\%, and 0.87\% at 95\% confidence for TOI-4010~b, c and d respectively. We fit our transmission spectra with Parker wind models and find that this corresponds to 95th-percentile upper limits of $10^{10.17}$g~s$^{-1}$, $10^{10.53}$g~s$^{-1}$, and $10^{10.50}$g~s$^{-1}$ on the mass loss rates of TOI-4010~b, c, and d respectively. Our non-detections are inconsistent with expectations from one-dimensional hydrodynamic models for solar composition atmospheres. We consider potential reductions in signal from a decreased host star XUV luminosity, planetary magnetic fields, enhanced atmospheric metallicities, and fractionation, and explore the implications of our measurements for the past evaporation histories of all three planets.

The upcoming SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) instrument for W.M. Keck Observatory will enable new imaging and low-/mid-resolution coronagraphic integral field spectroscopic observations over the wavelength range from 2-5 microns. At the heart of the instrument are two HgCdTe Teledyne Imaging H2RG detectors, designed for a 100kHz pixel clock rate (slow mode) with a fixed 4-channel readout. However, in ground-based operation at these wavelengths, the resulting minimum frame readout time will result in the infrared background saturating the detector. To enable high quality observations without saturation from the bright infrared sky background, we operate the detectors using a custom cable for buffered readout via the Teledyne Imaging SIDECAR ASIC followed by an AstroBlank/Markury Scientific MACIE controller card controlled by custom firmware. This combination allows the detector to be read out at faster pixel clock rates. This, in combination with the slow-mode H2RG, is what we characterize as hybrid fast-slow readout, enabling readout up to 18 times faster than would be possible in slow mode alone. In the UCLA Infrared Lab, we have performed room-temperature and cold tests with the H2RG detectors. We test and optimize full-frame data acquisition with pixel clock rates from 0.2-1.8 MHz. In these proceedings, we present a summary of the controller software used to operate the H2RG-ASIC-MACIE system. We present the methodology of, and preliminary results from, the UCLA tests of cryogenic operation of both H2RG detectors. We also outline the next steps in verification of detector performance, as well as integration with the SCALES instrument.

Motivated by the recent baryon acoustic oscillation measurements of DESI DR2 collaboration, this works presents an extended analysis of a cosmological model based on holographic dark energy within the framework of Unimodular Gravity. We probe the model with an extensive set of observations: cosmic chronometers, Pantheon Plus$+$SH0ES Type Ia supernovae, DESI DR2 BAO distances, quasar X-ray/UV fluxes (two independent calibrations), and Planck 2018 CMB data. The results are analyzed to assess the modelś ability to alleviate the Hubble tension and, in comparison with the standard $\Lambda$CDM framework, to determine which of the two scenarios is preferred according to Bayesian evidence. We conclude that the present implementation of holographic dark energy in Unimodular Gravity, while theoretically appealing, does not alleviate the Hubble tension and is not statistically preferred by Bayesian criteria when compared with the standard $\Lambda$CDM model. Nevertheless, in neither case does the preference become very strong or conclusive against it.

Spectroscopic redshift errors, including redshift uncertainty and catastrophic failures, can bias cosmological measurements from galaxy redshift surveys at sub-percent level. We investigate their impact on full-shape clustering analysis using contaminated mock catalogs. We find that redshift uncertainty introduces a damping effect on the power spectrum. This damping is scale-dependent and absorbed by counterterms in the clustering model, keeping parameter biases below $5\%$ for the DESI survey. Catastrophic failures reduce the power spectrum amplitude by an approximately constant factor scaling with contamination rate $f_c$. While this effect is negligible for the DESI ELG populations ($f_c=1\%$), the slitless-like errors, combining redshift uncertainty with $f_c=5\%$ catastrophics, introduce significant biases in cosmological constraints. For this case, shifts from $6\%$ to $16\%$ ($\sim2.2\sigma$ level) arise in estimating the fractional growth rate $df\equiv f/f^{\rm{fid}}$ and the log primordial amplitude $\ln(10^{10} A_{s})$. Applying a correction factor $(1-f_c)^2$ on the galaxy power spectrum mitigates the bias but weakens the parameter constraints due to new degeneracies. Alternatively, fixing $f_c$ to its expected value during fitting successfully restores the unbiased posterior without loss in constraint. Our results indicate that for space-based slitless surveys such as \textit{Euclid}, an accurate estimation of $f_c$ and its incorporation into the clustering model are essential to get unbiased cosmological constraints. Extending to evolving dark energy and massive neutrino cosmologies, we find that redshift errors do not bias the dark energy properties parametrized by $w_0$ and $w_a$, but lead to slightly weaker constraints on $\sum m_\nu$.

Context. Central stars of planetary nebulae (CSPNe) are essential for understanding the final evolutionary stages of low- and intermediate-mass stars. However, their study in extragalactic environments remains challenging due to their intrinsic faintness and the limited availability of high-quality data. Aims. We aim to provide a comprehensive and up-to-date catalogue of extragalactic CSPNe in order to enable a more complete view of their physical properties across different galactic environments and metallicities. Methods. The catalogue was assembled using data from the most recent and reliable literature sources. Priority was given to collecting effective temperatures and luminosities that have either been directly reported or consistently derived. When available, spectral types or specific spectral features -- such as P-Cygni profiles or broad H${\alpha}$ emission lines -- were also included. This approach allowed for broader characterisation of the sample, even when accurate classifications are not available. Results. We present a new compilation of extragalactic CSPNe -- the largest to date -- comprising over 800 objects located in the Magellanic Clouds, NGC 300, NGC 5128, and fifteen other nearby galaxies. This catalogue enables, for the first time, a global comparison of CSPNe physical parameters beyond the Milky Way. Updated Hertzsprung-Russell diagrams are provided featuring CSPNe from seven different galaxies, revealing trends and outliers that merit further investigation. The catalogue represents a valuable resource for future spectroscopic follow-up and for improving our understanding of post-AGB evolution in diverse galactic contexts.

In this study, we present novel calculations of X-ray polarization from radio-quiet and unobscured active galactic nuclei (AGNs) using the Monte Carlo code MONK, which includes all general and special relativity effects. Our geometric model, referred to as the ``wedge corona'', features a homogeneous cloud of electrons characterized by an aspect ratio of h/r and a radius that extends down to the innermost stable circular orbit around the central black hole (BH). Adopting the physical parameters of the Seyfert galaxy NGC 4151 as a baseline, we investigated various geometric and physical configurations of the BH-corona-accretion disk (AD) system, such as the coronal opening angle, temperature, optical depth, BH spin, and the inner radius of the disk. Finally, we compared our calculations with results from the Imaging X-ray Polarimetry Explorer (IXPE) for NGC 4151, the only radio-quiet and unobscured AGN with significant polarization detected by IXPE, to constrain the system's geometric parameters within the framework of the wedge corona model.

The initial mass and metallicity of stars both have a strong impact on their fate. Stellar axial rotation also has a strong impact on the structure and evolution of massive stars. In this study, we exploit the large grid of GENEC models, covering initial masses from 9 to 500 $M_{\odot}$ and metallicities ranging from $Z=10^{-5}$ (nearly zero) to 0.02 (supersolar), to determine the impact of rotation on their fate across cosmic times. Using the carbon-oxygen core mass and envelope composition as indicators of their fate, we predict stellar remnants, supernova engines, and spectroscopic supernova types for both rotating and non-rotating stars. We derive rates of the different supernova and remnant types considering two initial mass functions to help solve puzzles such as the absence of observed pair-instability supernovae. We find that rotation significantly alters the remnant type and supernova engine, with rotating stars favouring black hole formation at lower initial masses than their non-rotating counterparts. Additionally, we confirm the expected strong metallicity dependence of the fates with a maximum black hole mass predicted to be below 50 $M_{\odot}$ at SMC or higher metallicities. A pair-instability mass gap is predicted between about 90 and 150 $M_{\odot}$, with the most massive black holes below the gap found at the lowest metallicities. Considering the fate of massive single stars has far-reaching consequences across many different fields within astrophysics, and understanding the impact of rotation and metallicity will improve our understanding of how massive stars end their lives, and their impact on the universe.

Recent advances in CMOS technology have potential to significantly increase the performance, at low-cost, of an astronomical space telescope. Arrays of sensors in space missions are typically contiguous and act as a monolithic detector. A non-contiguous array, with gaps between individual commercial CMOS detectors, offers potential cost and schedule benefits but poses a unique challenge for stray/scattered light mitigation due to complexities in the optomechanics. For example, if the array of detectors is being fed a large field of view, then each detector will have a different angle of incidence. Any individual bandpass filters need to be held perpendicular to the incoming beam so as not to create variances of central wavelength transmission from detector to detector. It naturally follows that the optical design can force filter ghosts to fall between detectors. When dealing with well-focused, high-intensity beams, first and second order stray light path analyses must be conducted to determine scattered light from glints off of individual optics/opto-mechanics or detector specific vane structures. More mechanical structures are necessary for imaging with non-contiguous arrays, all of which have potential to increase scattered light. This proceeding will document various stray light mitigation strategies for a non-contiguous array of sensors in a space telescope.

Microlensing induced by the stellar field within a strong lensing galaxy can introduce fluctuations in the waveforms of strongly-lensed gravitational this http URL fitting these signals with templates that do not account for microlensing,possible degeneracies can lead to false evidence of certain intrinsic parameters,resulting in a misinterpretation of the properties of the underlying this http URL example,the wave effect of microlensing may mimic spin precessions,as both effects generically induce periodic waveform this http URL previous studies suggest that lensing-induced modulations can be distinguished from precession using parameter estimation under a geometric-optic approximation,it does not directly apply for lensed image through stellar fields due to large number of stars involved an wave-optic this http URL study aims to evaluate the degree of degeneracy between the stellar-field microlensing and spin precession,investigating whether microlensing leads false evidence of this http URL other words,to what extent observed SLGWs are identified with false evidence of this http URL main findings are as this http URL,assuming O5 sensitivity and parallel spins for the underlying binary black holes,microlensing-induced false evidence of precession is generally weak(15% of the events show significant evidence,30% if the signal-to-noise ratio doubles).Second,for highly magnified events,about 72% of the population show significant evidence of precession,which could serve as an identification criterion for this http URL implies the possibility of strong lensing for the recent event GW231123,which is in the mass gap and also shows evidence of this http URL,a moderate to strong positive correlation exists between microlensing strength and precession evidence,more pronounced in Type II this http URL suggests that stronger precession evidence may imply a stronger microlensing effect.

We present a fast and accurate formulation for computing the nonlinear matter power spectrum at one-loop order based on Unified Lagrangian Perturbation Theory (ULPT). ULPT decomposes the density field into the Jacobian deviation, capturing intrinsic nonlinear growth, and the displacement-mapping factor, accounting for large-scale distortions due to bulk flows. This structural separation leads to a natural division of the power spectrum into a source term and a displacement-mapping factor, ensuring infrared (IR) safety by construction. We implement an efficient numerical algorithm using FFTLog and FAST-PT, achieving approximately 2-second evaluations on a standard laptop. The results are validated against simulation-based emulators, including the Dark Emulator and Euclid Emulator 2. Across 100 sampled cosmologies, ULPT agrees with emulator predictions at the 2--3\% level up to \( k \simeq 0.4\,h\,\mathrm{Mpc}^{-1} \) for \( z \geq 0.5 \), without any nuisance parameters. Similar agreement is found in configuration space, where the two-point correlation function remains accurate down to \( r \simeq 10\,h^{-1}\mathrm{Mpc} \). Compared to standard perturbation theory, which fails at small scales due to series expansion of the displacement factor, ULPT maintains convergence by preserving its full exponential form. We also clarify the mechanism of BAO damping: exponential suppression by displacement and peak sharpening by nonlinear growth. The combination accurately reproduces BAO features seen in simulations. ULPT thus offers a robust, IR-safe, and computationally efficient framework for modeling large-scale structure in galaxy surveys. The numerical implementation developed in this work is publicly released as the open-source Python package \texttt{ulptkit} (this https URL).

Active galactic nuclei (AGN) jets are powerful drivers of galaxy evolution, depositing energy and momentum into the circumgalactic and intracluster medium (CGM/ICM) and regulating gas cooling and star formation. We investigate the dynamics of jet evolution in the self-similar regime using the smoothed particle hydrodynamics (SPH) code Gadget4-Osaka, systematically varying jet launching schemes, artificial viscosity prescriptions, mass resolution, and jet lifetimes. Our analysis combines quantitative diagnostics of jet size and energetics with detailed morphological and thermodynamic characterizations from slice maps and phase diagrams. We find that jet lobe growth follows analytic self-similar scaling relations and converges with resolution, but is highly sensitive to the choice of artificial viscosity. While the overall jet size tracks self-similar predictions, the partitioning of thermal and kinetic energy departs significantly from the idealized picture, reflecting enhanced dissipation and mixing. These results establish robust benchmarks for SPH-based jet modeling, provide insight into the physical and numerical factors shaping jet--medium interactions, and lay the groundwork for future studies of AGN feedback in realistic galactic and cluster environments.

Protoclusters, galaxy clusters' high redshift progenitors, hold the keys to understanding the formation and evolution of clusters and their member galaxies. However, their cosmological distances and spatial extensions (tens of Mpc) have inhibited complete mapping of their structure and constituent galaxies, which is key to robustly linking protoclusters to their descendants. Here we report the discovery of the Bigfoot, a tridimensional structure at $z = 3.98$ including 11 subgroups traced by 55 (700) spectroscopic (photometric) redshifts with JWST, extending over $15\times 37$ $\times 49{\rm{cMpc^3}}$ in the PRIMER-UDS field. Bigfoot's large-scale and mass function of member galaxies closely match constrained simulations' predictions for the progenitors of today's most massive clusters (${M_0} > 10^{15} {M_{_ \odot }}$). All subgroups with ${M_{\rm{h}}} > {10^{12.5}}{M_{_ \odot }}$ exhibit enhanced fractions of massive galaxies ($>{10^{10.0} {M_{_ \odot }}}$) compared to lower-mass halos and the field, demonstrating the accelerated formation of massive galaxies in massive halos. The presence of this massive protocluster with a large central halo (${10^{13.0} {M_{_ \odot }}}$) in a JWST deep field bears important cosmological implication that favors high ${\sigma _8}$ of PLANCK cosmology over low-redshift probes.

The overwhelming majority of CVs have orbital periods shorter than 10 hr. However, a few have much longer periods, and their formation and existence pose challenges for the CV evolution models. These extremely long-period CVs must host nuclearly evolved donor stars, as otherwise, the companion of the white dwarf would be too small to fill its Roche lobe. This makes them natural laboratories for testing binary evolution models and accretion processes with subgiant donors. To shed light on the formation and evolution of accreting compact objects with subgiant companions, we investigated two extremely long-period CVs in detail, namely V479 And and V1082 Sgr. We searched for reasonable formation pathways to explain their refined stellar and binary parameters. We used a broad set of new observations, including ultraviolet and infrared spectroscopy, results of circular polarimetry, and improved Gaia distance estimates to determine fundamental parameters to be confronted with numerical simulations. Furthermore, we utilized the MESA code to conduct numerical simulations, employing state-of-the-art prescriptions, such as the CARB model for strong magnetic braking. Both systems have unusual chemical compositions and very low masses for their assigned spectral classes. This most likely indicates that they underwent thermal timescale mass transfer. We found models for both that can reasonably reproduce their properties. We conclude that the donor stars in both V479 And and V1082 Sgr are filling their Roche lobes. Our findings suggest that orbital angular momentum loss is stronger due to magnetic braking in CVs with subgiant donors compared to those with unevolved donors. In addition, our findings suggest that extremely long-period CVs could significantly contribute to the population of double white dwarf binaries in close orbits.

Hot ionized interstellar medium interlinks star formation and stellar feedback processes, redistributing energy, momentum, and material throughout galaxies. We use X-ray data from $Chandra$ to extract the hot gas emission from 78 of the most luminous infrared-selected galaxies in the local Universe. In the extreme star-forming environments, the intrinsic thermal X-ray luminosity of hot gas ($L_{\rm 0.5 - 2\,keV}^{\rm gas}$) shows a significant excess over the predictions of the standard linear $L_{\rm X}$$-$SFR relation for most objects with very high star formation rates (SFRs). The contribution of active galactic nuclei (AGNs) appears to have little impact on the global hot gas luminosity. For galaxies with SFR $\gt$ 50 ${M_{\rm \odot}}\,\,{\rm yr^{-1}}$, the Bayesian analysis gives a super-linear relation of ${\rm log}(L_{\rm 0.5-2\,keV}^{\rm gas} /{\rm erg\,s^{-1}})=1.34\,{\rm log}({\rm SFR}/{M_{\rm \odot}}\,{\rm yr^{-1}})+39.82$, similar to that found in the central regions of normal spiral galaxies. These results suggest a scenario in which the merger of galaxies delivers substantial amounts of gas, triggering intense star formation in both the nuclear region and the galactic disk, and ultimately enhancing the global thermal X-ray emission. The ratio of the apparent thermal luminosity in the 0.5$-$2 keV band ($L_{\rm 0.5 - 2\,keV}^{\rm appar}$) to $L_{\rm 0.5 - 2\,keV}^{\rm gas}$ shows statistically significant negative correlations with the intrinsic column density ($N_{\rm H}$) and SFR. Moreover, in contrast to the luminosity ratio, SFR shows a moderate positive correlation with intrinsic $N_{\rm H}$. This suggests that the correlation between $L_{\rm 0.5 - 2\,keV}^{\rm appar}$/$L_{\rm 0.5 - 2\,keV}^{\rm gas}$ and SFR may be driven by the underlying $L_{\rm 0.5 - 2\,keV}^{\rm appar}$/$L_{\rm 0.5 - 2\,keV}^{\rm gas}$$-$$N_{\rm H}$ and SFR$-$$N_{\rm H}$ relations.

We develop a new method for simulating stellar streams generated by globular clusters using angle-action coordinates. This method reproduces the variable mass-loss and variable frequency of the stripped stars caused by the changing tidal forces acting on the cluster as it moves along an eccentric orbit. The model incorporates realistic distributions for the stripping angle and frequency of the stream stars both along and perpendicular to the stream. The stream is simulated by generating random samples of stripped stars and integrating them forward in time in angle-frequency space. Once the free parameters are calibrated, this method can be used to simulate the internal structure of stellar streams more quickly than N-body simulations, while achieving a similar level of accuracy. We use this model to study the surface density of the stellar stream produced by the globular cluster M68 (NGC 4590). We select $291$ stars from the Gaia-DR3 catalogue along the observable section that are likely to be members of the stream. We find that the width of the stream is too large to be explained by stars stripped from the cluster alone. We simulate the stream using the present method and include the Gaia selection function and observational errors, and the process of separating the stream stars from the foreground. By comparing these results with the observed data, we estimate the age of the stream, or equivalently the cluster accretion time, to be $3.04_{-0.29}^{+5.63}$ Gyr, and the mass-loss of the cluster to be $0.496 \pm 0.030$ M$_{\odot}$ Myr$^{-1}$ arm$^{-1}$.

The gravitational lensing effect of gamma-ray bursts (GRBs) holds significant and diverse applications in the field of astronomy. Nevertheless, the identification of millilensing events in GRBs presents substantial challenges. We re-evaluate the gravitational lensing candidacy of six previously proposed GRBs (GRB 081122A, GRB 081126A, GRB 090717A, GRB 110517B, GRB 200716C, and GRB 210812A) using a comprehensive set of temporal and spectral diagnostics. These include $\chi^2$ light-curve similarity tests, photon-count-based hardness ratio ($HR_{count}$) comparisons, $T_{90}$ duration measurements, spectral lag, Norris pulse-shape fitting, and both time-resolved and time-integrated spectral analyses. We propose an evaluation framework, any single test that reveals a statistically significant inconsistency between the two pulses is sufficient to reject the lensing hypothesis for that this http URL certain diagnostics, such as $T_{90}$ and parametric model fits, have known limitations, they are applied and interpreted in conjunction with the more robust, model-independent $\chi^2$ and $HR_{count}$ tests. For all six GRBs, at least one diagnostic shows a significant discrepancy, leading us to conclude that none are consistent with a gravitational lensing interpretation.

One of the most outstanding questions in contemporary astrophysics is: What is the significance of galaxy morphology? What physical processes underlier the morphologies we observe and is a galaxy's internal structure driving its evolution (nature) or is it a sign of the external processes which drive galaxy evolution (nurture)? We aim to understand the color dichotomy and gradients in bulges and disks along the Hubble sequence. We fit Sérsic functions to the 2D light distributions in the $g$, $r$, $i$ bands to bulges and disks of the large EFIGI sample of galaxies with high quality morphological classification. In early-type galaxies, bulges and disks have similarly red and nearly uniform colors. Disks become significantly bluer with increasing lateness of their types and bulges get slightly redder because of patchy dust. Disks have increasingly blue colors with increasing radius, whereas dust extinction and scattering leads to smaller effective radii of the bulges and lower steepness of the best-fit Sérsic profiles in $g$ versus $i$. The impact is not uniform with Hubble type and the bulges of intermediate-type spirals (Sb-Sc) have the reddest mean colors, the largest scatter in their colors, and show the largest mean and scatter in their color gradients. Disks of the intermediate-type galaxies show the strongest color gradients. We interpret these properties of the bulges and disks of intermediate-type spirals as being due to dust extinction and scattering which we hypothesize to be an indicator of the gas content and inflow of gas. if early-type galaxies do evolve from massive spiral galaxies, typically intermediate-type spirals, these color gradients are signs of in-situ stellar growth within their bulges, likely driven by morphological structure in their disk. These results favor secular evolution (nature) as the primary driver of galaxy evolution in the local Universe.

We develop a perturbative model to describe large-scale structure in cosmologies where dark matter consists of a mixture of cold (CDM) and warm (WDM) components. In such mixed dark matter (MDM) scenarios, even a subdominant warm component can introduce distinctive signatures via its free-streaming effects, altering the evolution of density and velocity perturbations. We present linear-order solutions for both total and relative perturbations in the two-fluid system, identifying novel contributions to galaxy bias caused by the relative density and velocity modes between the components. Incorporating these effects into the galaxy bias expansion, we compute the linear galaxy power spectrum in both real and redshift space. Using Fisher matrix forecasts, we assess the sensitivity of upcoming surveys such as DESI and PFS to MDM scenarios. Our results demonstrate that neglecting relative perturbations can lead to significant biases in inferred constraints on the warm dark matter fraction, particularly for lighter WDM masses ($\lesssim 150~\mathrm{eV}$ and $\lesssim 80~\mathrm{eV}$) for PFS and DESI, respectively. This framework provides a consistent and generalizable approach for incorporating multi-component dark matter dynamics into galaxy clustering analyses.

We examined F814W and F606W images of dwarf galaxies from the Hubble Space Telescope archive, which were obtained under the HST SNAP programs 17159 to 17797. Among 58 observed dwarfs located outside the Local Group, we found only a few objects that were confidently resolved into stars. We determined two new distances for the galaxies: dw1252+2215 ($5.32\pm0.20$ Mpc) and dw1234+3952 ($4.34\pm0.16$ Mpc) via the Tip of the Red Giant Branch. They turned out to be new probable dwarf satellites of the nearby luminous spiral galaxies NGC 4826 and NGC 4736, respectively. We also note that recent SNAP surveys vary in their productivity in measuring new galaxy distances by more than an order of magnitude.

Using 16 years of Fermi-LAT data and resources from the NASA/IPAC Extragalactic Database (NED), we constructed two high-precision catalogs: the updated 4FGL-Xiang-DR2 (DR2) and a supplementary version of the fifth edition of Roma-BZCAT (5BZCAT\_err), both featuring refined positional uncertainties. We performed a spatial cross-identification between the two catalogs and developed a systematic three-step analytical pipeline: (1) efficient retrieval of positional uncertainties and multi-wavelength fluxes from 5BZCAT\_err, (2) calculation of spatial association probabilities with DR2, and (3) statistical modeling of multi-band fluxes, using the Box--Cox transformation and a truncated normal distribution. Through this process, we identified 17 new blazar candidates. Fermi-LAT analysis reveals that, except for J1043.7+5323, which exhibits significant flux variability above 100 MeV, the remaining sources display stable fluxes, without apparent spatial extension or spectral curvature. Multi-wavelength flux modeling shows that 15 of the 17 sources fall within the 2$\sigma$ confidence interval of the distribution model, demonstrating strong statistical consistency with known blazar samples. As Fermi-LAT data continues to accumulate, the remaining two sources are expected to converge toward the high-confidence region, providing further support for the common-source hypothesis.

We investigate the environmental dependence of galaxy mergers using high-resolution imaging data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. We focus on galaxy groups and clusters at $z < 0.2$ identified by the Sloan Digital Sky Survey as a laboratory of galaxy environment. We develop a new non-parametric classification scheme that combines the Gini-$M_{20}$ statistics with the shape asymmetry parameter, enabling robust identification of mergers with both central concentration and outer morphological disturbances. Applying this method to a sample of 33,320 galaxies at $0.075 \leq z < 0.2$ taken by the HSC, we identify 12,666 mergers, corresponding to a merger fraction of 38%. Our results are consistent with visual classifications from the GALAXY CRUISE project, validating the effectiveness of our method. We find that the merger fraction increases with redshift for all subsamples (field galaxies, galaxy pairs, and cluster members), and also shows a strong radial gradient within clusters, increasing toward the center. These trends suggest that merger activity is enhanced both at earlier cosmic times and in denser environments, particularly in galaxy groups. We also find tentative evidence that mergers may contribute to AGN triggering in cluster cores. Our study highlights the utility of combining non-parametric morphological diagnostics for large-scale merger identification and provides new insights into the role of environment in galaxy evolution.

Accreting massive black hole binaries (MBHBs) often display periodic variations in their emitted radiation, providing a distinctive signature for their identification. In this work, we explore the MBHBs identification via optical variability studies by simulating the observations of the LSST survey. To this end, we generate a population of MBHBs using the L-Galaxies semi-analytical model, focusing on systems with observed orbital periods $\leq$ 5 years. This ensures that at least two complete cycles of emission can be observed within the 10-year mission of LSST. To construct mock optical light curves, we first calculate the MBHB average magnitudes in each LSST filter by constructing a self-consistent SED that accounts for the binary accretion history and the emission from a circumbinary disc and mini-discs. We then add variability modulations by using six 3D hydrodynamic simulations of accreting MBHBs with different eccentricities and mass ratios as templates. To make the light curves realistic, we mimic the LSST observation patterns and cadence, and we include stochastic variability and LSST photometric errors. Our results show from $10^{-2}$ to $10^{-1}$ MBHBs per square degree, with light curves that are potentially detectable by LSST. These systems are mainly low-redshift ($z\lesssim1.5$), massive ($\gtrsim10^{7}\, M_{\odot}$), equal-mass (${\sim} 0.8$), relatively eccentric (${\sim}0.6$), and with modulation periods of around $3.5$ years. Using periodogram analysis, we find that LSST variability studies have a higher success rate ($>$50%) for systems with high eccentricities ($e>$0.6). Additionally, at fixed eccentricity, detections tend to favour systems with more unequal mass ratios. The false alarm probability shows similar trends. Circular binaries systematically feature high values ($\gtrsim 10^{-1}$). Eccentric systems have low-FAP tails, down to $\sim10^{-8}$.

Understanding the coronal geometry in different states of black hole X-ray binaries is important for more accurate modeling of the system. However, it is difficult to distinguish different geometries by fitting the observed Comptonization spectra. In this work, we use the Monte Carlo ray-tracing code MONK to simulate the spectra for three widely proposed coronal geometries: sandwich, spherical, and lamppost, varying their optical depth and size (height). By fitting the simulated NuSTAR observations with the simplcut*kerrbb model, we infer the possible parameter space for the hard state and soft state of different coronal geometries. The influence of the disk inclination angle and black hole spin is discussed. We find that for the lamppost model the disk emission is always dominant, making it incompatible in the hard state. While the sandwich and spherical models can produce similar spectra in both the hard and soft states, the simulated IXPE polarimetric spectra show the potential to break this degeneracy.

We present the detection and characterisation of the TOI-1438 multi-planet system discovered by TESS. We collected a series of follow-up observations including high-spectral resolution observations with HARPS-N over a period of five years. Our modelling shows that the K0V star hosts two transiting sub-Neptunes with Rb = 3.04 +/- 0.19 RE, Rc = 2.75 +/- 0.14 RE, Mb = 9.4 +/- 1.8 ME, and Mc = 10.6 +/- 2.1 ME. The orbital periods of planets b and c are 5.1 and 9.4 days, respectively, corresponding to instellations of 145 +/- 10 and 65 +/- 4 FE. The bulk densities are 1.8 +/- 0.5 and 2.9 +/- 0.7 g cm-3, respectively, suggesting a volatile-rich interior composition. We computed a set of planet interior structure models. Planet b presents a high-metallicity envelope that can accommodate up to 2.5 % in H/He in mass, while planet c cannot have more than 0.2 % as H/He in mass. For any composition of the core considered (Fe-rock or ice-rock), both planets would require a volatile-rich envelope. In addition to the two planets, the radial velocity (RV) data clearly reveal a third signal, likely coming from a non-transiting planet, with an orbital period of 7.6 +1.6 -2.4 years and a radial velocity semi-amplitude of 35+3-5 m s-1. Our best fit model finds a minimum mass of 2.1 +/- 0.3 MJ and an eccentricity of 0.25+0.08-0.11. However, several RV activity indicators also show strong signals at similar periods, suggesting this signal might (partly) originate from stellar activity. More data over a longer period of time are needed to conclusively determine the nature of this signal. If it is confirmed as a triple-planet system, TOI-1438 would be one of the few detected systems to date characterised by an architecture with two small, short-period planets and one massive, long-period planet, where the inner and outer systems are separated by an orbital period ratio of the order of a few hundred.

An alternative, new laser link acquisition scheme for the triangular constellation of spacecraft (SCs) in deep space in the detection of gravitational waves is considered. In place of a wide field CCD camera in the initial stage of laser link acquisition adopted in the conventional scheme, an extended Kalman filter based on precision orbit determination is incorporated in the point ahead angle mechanism (PAAM) to steer the laser beam in such a way to narrow the uncertainty cone and at the same time avoids the heating problem generated by the CCD camera.A quadrant photodetector (QPD) based on the Differential Power Sensing (DPS) technique, which offers a higher dynamic range than differential wavefront sensing (DWS), is employed as the readout of the laser beam spot. The conventional two stages (coarse acquisition and fine acquisition) are integrated into a single control loop. The payload structure of the ATP control loop is simplified and numerical simulations, based on a colored measurement noise model that closely mimics the prospective on-orbit conditions, demonstrate that the AEKF significantly reduces the initial uncertainty region by predicting the point ahead angle (PAA) even when the worst case scenario in SC position (navigation) error is considered.

We explore the potential variation of two fundamental constants, the fine-structure constant $\alpha$ and the proton-to-electron mass ratio $\mu$, within the framework of modified gravity theories and finite-temperature effects. Utilising high-precision white dwarf observations from the Gaia-DR3 survey, we construct a robust mass--radius relation using a Bayesian-inspired machine learning framework. This empirical relation is rigorously compared with theoretical predictions derived from scalar-tensor gravity models and temperature-dependent equations of state. Our results demonstrate that both underlying gravitational theory and temperature substantially influence the inferred constraints on $\alpha$ and $\mu$. We obtain the strongest constraints as $|\Delta\alpha/\alpha|=2.10^{+32.56}_{-39.26}\times10^{-7}$ and $|\Delta\mu/\mu|=1.61^{+37.16}_{-34.67}\times10^{-7}$ for modified gravity parameter $\gamma\simeq -3.69\times10^{13}\,\mathrm{cm}^2$, while for the finite temperature case, these are $|\Delta\alpha/\alpha|=1.60^{+37.31}_{-35.42}\times10^{-7}$ and $|\Delta\mu/\mu|=1.23^{+37.02}_{-35.71}\times10^{-7}$ for $T \simeq 1.1 \times 10^7\rm\, K$. These findings yield tighter constraints than those reported in earlier studies and underscore the critical roles of gravitational and thermal physics in testing the constancy of fundamental parameters.

Massive stars play a significant role in different branches of astronomy, from shaping the processes of star and planet formation to influencing the evolution and chemical enrichment of the distant universe. Despite their high astrophysical significance, these objects are rare and difficult to detect. With Gaia's advent, we now possess extensive kinematic and photometric data for a significant portion of the Galaxy that can unveil, among others, new populations of massive star candidates. In order to produce bonafide bright (G magnitude $<$ 12) massive star candidate lists (threshold set to spectral type B2 or earlier but slight changes in this threshold also explored) in the Milky Way subject to be followed up by future massive spectroscopic surveys, we have developed a Gaia DR3 plus literature data based methodology. We trained a Balanced Random Forest (BRF) with the spectral types from the compilation by Skiff et al. (2014) as labels. Our approach yields a completeness of $\sim80\%$ and a purity ranging from $0.51 \pm 0.02$ for probabilities between 0.6 and 0.7, up to $0.85 \pm 0.05$ for the 0.9-1.0 range. To externally validate our methodology, we searched for and analyzed archival spectra of moderate to high probability (p $>$ 0.6) candidates that are not contained in our catalog of labels. Our independent spectral validation confirms the expected performance of the BRF, spectroscopically classifying 300 stars as B3 or earlier (due to observational constraints imposed in the B0-3 range), including 107 new stars. Based on the most conservative yields of our methodology, our candidate list could increase the number of bright massive stars by $\sim$50\%. As a byproduct, we developed an automatic methodology for spectral typing optimized for LAMOST spectra, based on line detection and characterization guiding a decision path.

Current galaxy formation models predict the existence of X-ray-emitting gaseous halos around Milky Way (MW)-type galaxies. To investigate properties of this coronal gas in MW-like galaxies, we analyze a suite of high-resolution simulations based on the {\it SMUGGLE} framework, and compare the results with X-ray observations of both the MW and external galaxies. We find that for subgrid models incorporating any form of stellar feedback, e.g., early feedback (including stellar winds and radiation) and/or supernova (SN) explosions, the total $0.5-2$\,keV luminosity is consistent {\it within uncertainties} with X-ray observations of the MW and with scaling relations derived for external disk galaxies. However, all models exhibit an X-ray surface brightness profile that declines too steeply beyond $\sim5$\,kpc, underpredicting the extended emission seen in recent eROSITA stacking results. Across all subgrid prescriptions, the simulated surface brightness and emission measure fall below MW observations by at least $1-2$ orders of magnitude, with the most severe discrepancy occurring in the no-feedback model. Our results suggest that (i) stellar feedback primarily shapes the innermost hot atmosphere (central $\sim5$\,kpc), with comparable contributions from early feedback and SNe to the resulting X-ray luminosity; (ii) additional mechanisms such as gravitational heating, AGN feedback, and/or Compton effects of GeV cosmic ray are necessary to generate the extended, volume-filling hot gaseous halo of MW-mass galaxies; (iii) the origins of hot corona in MW-like galaxies are partially distinct from those of the warm ($\sim10^5$\,K) gas, by combining our previous finding that the {\it SMUGGLE} model successfully reproduces the kinematics and spatial distribution of MW \ion{O}{6} absorbers \citep{2024ApJ...962...15Z}.

With periods much longer than the duration of current pulsar timing surveys, gravitational waves in the picohertz (pHz) regime are not detectable in the typical analysis framework for pulsar timing data. However, signatures of these low-frequency signals persist in the slow variation of pulsar timing parameters. In this work, we present the results of the first Bayesian search for continuous pHz gravitational waves using the drift of two sensitive pulsar timing parameters -- time derivative of pulsar binary orbital period $\dot{P}_b$ and second order time derivative of pulsar spin period $\ddot{P}$. We apply our new technique to a dataset with more than double the number of pulsars as previous searches in this frequency band, achieving an order-of-magnitude sensitivity improvement. No continuous wave signal is detected in current data; however, we show that future observations by the Square Kilometre Array will provide significantly improved sensitivity and the opportunity to observe continuous pHz signals, including the early stages of supermassive black hole mergers. We explore the detection prospects for this signal by extending existing population models into the pHz regime, finding that future observations will probe phenomenologically-interesting parameter space. Our new Bayesian technique and leading sensitivity in this frequency domain paves the way for new discoveries in both black hole astrophysics and the search for new physics in the early universe.

Absorption Line Quasars (ALQs) generally exhibit significant outflows that may interact with the surrounding medium, resulting in radio emission. We selected a sample of 13 powerful radio-quiet (RQ) ALQs, where the UV outflow kinetic power is measurable, and detected nine of them with the Very Large Array at 5.5 GHz and 9.0 GHz. The radio emission is mostly unresolved, indicating no emission beyond a spatial scale of ~ 1-3 kpc. In the nine detected objects, the radio spectral slope at 5.5-9.0 GHz is steep (< -0.5) in five objects and is flat or inverted (> -0.5) in four objects. We discuss how the steep-slope emission can be associated with the UV outflows, and how the flat-slope emission can be intrinsically steep but flattened by free-free absorption from the UV outflowing gas. However, we find no correlation between the radio luminosity and the estimated outflow kinetic power, which suggests that the outflows are not a major source of the observed radio emission. In addition, the radio loudness of these RQ ALQs is comparable to that of typical RQ quasars, implying that the UV outflows do not lead to excess radio emission. Follow-up radio observations can test the free-free absorption interpretation and can be used as a new probe for outflows in AGN.

The occurrence rate of close-in super-Earths is higher around M-dwarfs compared to stars of higher masses. In this work we aim to understand how the super-Earth population is affected by both the stellar mass, the size of the protoplanetary disc, and viscous heating. We utilise a standard protoplanetary disc model with both irradiated and viscous heating together with a pebble accretion model to simulate the formation and migration of planets. We find that if the disc is heated purely through stellar irradiation, inwards migration of super-Earths is very efficient, resulting in the close-in super-Earth fraction increasing with increasing stellar mass. In contrast, when viscous heating is included, planets can undergo outwards migration, delaying migration to the inner edge of the protoplanetary disc, which causes a fraction of super-Earth planets to grow to become giant planets instead. This results in a significant reduction of inner super-Earths around high-mass stars and an increase in the number of giant planets, both of which mirror observed features of the planet population around high-mass stars. This effect is most pronounced when the protoplanetary disc is large, since such discs evolve over a longer time-scale. We also test a model when we inject protoplanets at a fixed time early on in the disc lifetime. In this case, the fraction of close-in super-Earths decreases with increasing stellar mass in both the irradiated case and viscous case, since longer disc lifetimes around high-mass stars allows for planets to grow into giants instead of super-Earths for most injection locations.

The Cygnus region is a vast star-forming complex harbouring a population of powerful objects, including massive star clusters and associations, Wolf-Rayet stars, pulsars, and supernova remnants. The multi-wavelength picture is far from understood, in particular the recent LHAASO detection of multi-degree scale diffuse gamma-ray emission up to PeV energies. We aim to model the broadband gamma-ray data, discriminating plausible scenarios amongst all candidate accelerators. We consider in particular relic hadronic emission from a supernova remnant expanding in a low-density environment and inverse Compton emission from stellar-wind termination shocks in the Cygnus OB2 stellar association. We first estimate the maximum particle energy from a 3D hydrodynamical simulation of the supernova remnant scenario. The transport equation is then solved numerically to determine the radial distribution of non-thermal protons and electrons. In order to compute synthetic gamma-ray spectra and emission maps, we develop a 3D model of the gas distribution. This includes, firstly, a HI component with a low-density superbubble around Cygnus OB2 and, secondly, molecular clouds lying at the edge of the superbubble and in the foreground. We find that a powerful, ~50 kyr-old supernova remnant can account for both the morphology and spectrum from 10 TeV-PeV. At PeV energies, the microquasar Cygnus X-3 and diffuse Galactic cosmic rays might also contribute to the flux. Below about 10 TeV, hadronic models are incompatible with the expected existence of a superbubble centred on Cygnus OB2. Instead, the spectrum is well fitted with inverse Compton emission from electrons accelerated at stellar-wind termination shocks in Cygnus OB2 in line with existing multi-wavelength limits.

KASCADE-Grande was dedicated to measuring the energy spectrum and mass composition of cosmic rays in the energy range of 10 PeV to 1 EeV. We observed a knee-like structure in the heavy mass component at around 100 PeV and an ankle-like structure in the light component. In this contribution, we present updated energy spectra based on shower size measurements, using the post-LHC hadronic models QGSJet-II-04, EPOS-LHC, and SIBYLL 2.3d, including accounting for shower-to-shower fluctuations. In addition, the newly released EPOS-LHC-R model is tested for the first time with KASCADE-Grande. We will compare and discuss the results obtained using the different hadronic interaction models.

The CoRoT (Convection, Rotation, and planetary Transits) mission still holds a large trove of high-quality, underused light curves with excellent signal-to-noise and continuous coverage. This paper, the first in a series, identifies and classifies variable stars in CoRoT fields whose variability has not been analyzed in the main repositories. We combine simulations and real data to test a moving-average scheme that mitigates instrumental jumps and enhances the recovery of short-period signals (<1 day) in roughly 20-day time series. For classification, we adopt a supervised selection built on features extracted from folded light curves using the double period, and we construct template-based models that also act as a new classifier for well-sampled light curves. We report 9,272 variables, of which 6,249 are not listed in SIMBAD or VSX. Our preliminary classes include 309 Beta Cephei, 3,105 Delta Scuti, 599 Algol-type eclipsing binaries, 844 Beta Lyrae eclipsing binaries, 497 W Ursae Majoris eclipsing binaries, 1,443 Gamma Doradus, 63 RR Lyrae, and 32 T Tauri stars. The resulting catalog inserts CoRoT variables into widely used astronomical repositories. Comparing sources in the inner and outer Milky Way, we find significant differences in the occurrence of several classes, consistent with metallicity and age gradients. The ability to recover sub-day periods also points to automated strategies for detecting longer-period variability, which we will develop in subsequent papers of this series.

Little Red Dots (LRDs), newly identified compact and dusty galaxies with an unexpectedly high number density observed by JWST, have an unusual "V-shaped" rest-frame UV to near-infrared spectral energy distribution (SED). A group of hyper-luminous, obscured quasars with excess blue emission, called Blue-excess Hot Dust-Obscured Galaxies (BHDs), also exhibit qualitatively similar SEDs to those of LRDs. They represent a rare population of galaxies hosting supermassive black holes (SMBHs) accreting near the Eddington limit at redshifts z \sim 1--4. In this study, we compare their multi-wavelength SEDs to investigate whether LRDs, or a subset of them, could be high-redshift analogs of BHDs. Our analysis reveals that despite their similar "V-shape" SEDs, LRDs appear to be a different population than BHDs. The "V-shape" of BHDs appear at longer wavelengths compared to LRDs due to different selection strategies, suggesting LRDs have much less dust attenuation than typical BHDs. The bluer colors in the rest-frame infrared (continuum) emission of LRDs suggest the absence of hot dust heated by AGN accretion activities. We also argue that the blue excess in LRDs is unlikely from AGN scattered light. The compact morphologies and lower X-ray detection frequencies of LRDs suggest a distinct formation pathway from BHDs -- which are thought to be powered by super-Eddington accretion onto central SMBHs following major galaxy mergers.

We present an independent calibration of the photometric redshift (photo-$z$) distributions for source galaxies in the HSC-Y3 weak lensing survey using small-scale galaxy-galaxy lensing. By measuring the tangential shear around spectroscopic lens galaxies from GAMA, SDSS, and DESI, divided into fifteen narrow redshift bins, we compute shear ratios that are sensitive to the mean redshift of source galaxies. Using a blinded analysis, we derive constraints on the photo-$z$ bias parameters in source bins 2, 3 and 4, achieving signal-to-noise ratios of 59, 75, and 62, respectively. Our constraints for $\Delta z_2$, $\Delta z_3$ and $\Delta z_4$ are consistent with those from HSC-Y3 cosmic shear modeling. We observe a mild shift in the $\Delta z_3$-$\Delta z_4$ plane due to the heterogeneous depth of the lens sample, which disappears when using only DESI-DR1 lenses. Combining shear-ratio measurements with cosmic shear data, we obtain joint constraints on cosmological parameters: $\Omega_{\rm m} = 0.286_{-0.074}^{+0.038}$ and $S_8 = 0.760_{-0.145}^{+0.044}$, consistent with cosmic shear-only results. This work demonstrates the utility of small-scale lensing as an independent probe for calibrating photometric redshift bias in weak lensing cosmology.

Cosmic rays around the so-called knee in the spectrum at around PeV primary energy are generally galactic in origin. Observations on the form of their energy spectrum and their mass composition are fundamental tools to understand the origin, acceleration and propagation mechanism of high-energy cosmic rays. In addition, it is required to find signatures to clarify the transition from galactic to extragalactic sources, which are believed to be responsible for the highest-energy cosmic rays above EeV. This brief review focuses on recent experimental results around the knee of the all-particle energy spectrum and composition in the energy range of the knee up to EeV energies.

We provide new line-driven wind models for OB stars with metallicities down to $0.01\,Z_\odot$. The models were calculated with our global wind code METUJE, which solves the hydrodynamical equations from nearly hydrostatic photosphere to supersonically expanding stellar wind together with the equations of statistical equilibrium and the radiative transfer equation. The models predict the basic wind parameters, namely, the wind mass-loss rates and terminal velocities just from the stellar parameters. In general, the wind mass-loss rates decrease with decreasing metallicity and this relationship steepens for very low metallicities, $Z\lesssim0.1\,Z_\odot$. Down to metallicities corresponding to the Magellanic Clouds and even lower, the predicted mass-loss rates reasonably agree with observational estimates. However, the theoretical and observational mass-loss rates for very low metallicities exhibit significant scatter. We show that the scatter of observational values can be caused by inefficient shock cooling in the stellar wind, which leaves a considerable fraction of the wind at too high temperatures with waning observational signatures. The scatter of theoretical predictions is caused by a low number of lines that effectively accelerate the wind at very low metallicities.

We investigate the nature and spectroscopic diversity of early galaxies from a sample of 40 sources at z>10 with JWST/NIRSpec prism observations, the largest of its kind thus far. We compare the properties of strong UV line emitters, as traced by intense CIV emission, with those of more "typical" sources with weak or undetected CIV. The more typical (or "CIV-weak") sources reveal significant scatter in their CIII] line strengths, UV continuum slopes, and physical sizes, spanning CIII] equivalent widths of ~1-51 Å, UV slopes of $\beta$~-1.6 to -2.6, and half-light radii of ~50-1000 pc. In contrast, CIV-strong sources generally occupy the tail of these distributions, with CIII] EWs of 16-51 Å, UV slopes $\beta$<-2.5, compact morphologies ($r_{50}$<100 pc), and elevated star formation surface densities ($\Sigma_{SFR}$>100 $M_{\odot}yr^{-1}kpc^{-2}$). Collectively these properties are consistent with concentrated starbursts that temporarily outshine the extended structure of the galaxy. Comparing average properties from composite spectra, we find the diversity of the sample is primarily driven by bursts and lulls of star formation on very short timescales (<3 Myr), where strong CIV emitters are observed at the apex of these phases and sources devoid of emission lines represent periods of relative inactivity. An apparent association between strong CIV and enhanced nitrogen abundance suggests both features may be modulated by the same duty cycle and reflect a generic mode of star formation. We show that AGN are unlikely to be a significant contributor to this duty cycle based on a comparison of UV line diagnostics to photoionisation models, although some non-thermal activity cannot be fully ruled out. Our results support a unified evolutionary picture whereby transient bursts and lulls can explain the spectral diversity and early growth of bright galaxies in the first 500 Myr.

Identifying Earth-like planets outside out solar system is a leading research goal in astronomy, but determining if candidate planets have atmospheres, and more importantly if they can retain atmospheres, is still out of reach. In this paper, we present our study on the impact of enhanced EUV flux on the stability and escape of the upper atmosphere of an Earth-like exoplanet using the Global Ionosphere and Thermosphere Model (GITM). We also investigate the differences between one- and three-dimensional solutions. We use a baseline case of EUV flux experienced at the Earth, and multiplying this flux by a constant factor going up to 50. Our results show a clear evidence of an inflated and elevated ionosphere due to enhanced EUV flux, and they provide a detailed picture of how different heating and cooling rates, as well as the conductivity are changing at each EUV flux level. Our results also demonstrate that one-dimensional solutions are limited in their ability to capture a global atmosphere that are not uniform. We find that a threshold EUV flux level for a stable atmosphere occurs around a factor of 10 times the baseline level, where EUV fluxes above this level indicate a rapidly escaping atmosphere. This threshold EUV flux translates to about 0.3AU for a planet orbiting the Sun. Thus, our findings indicate that an Earth-like exoplanet orbiting its host star in a close-in orbit is likely to lose its atmosphere quickly.

Studying young, high-mass stellar objects is challenging for testing models of massive star formation due to their great distances, often kiloparsecs away. This requires extremely high-angular resolution to resolve features like accretion discs around massive protostars. Consequently, while powerful, collimated outflows are evident in massive protostars, the compact accretion discs anticipated at their centres are still proving difficult to pinpoint. This study presents ALMA continuum and molecular line observations at 1.3 mm of the massive protostar W75N(B)-VLA3. The observations achieve an angular resolution of $\sim$0.12$^{\prime\prime}$ ($\sim$156 au). Dense gas tracers reveal a circumstellar disc of $\sim$450 au in radius surrounding VLA3, with an orientation perpendicular to its associated thermal radio jet. From the millimetre continuum, a total mass of $\approx$0.43-1.74 $M_\odot$ is estimated for the disc. The disc's velocity profile is consistent with Keplerian rotation around a protostar of $\approx$16 $M_\odot$. This adds VLA3 to the small number of massive disc-protostar-jet systems documented in the literature with a centrifugally supported disc with a radius less than 500 au. Additionally, we detected H30$\alpha$ recombination line emission towards the radio jet powered by VLA3. Despite limitations in the spatial and spectral resolution, our data reveal a very broad line, indicative of high-velocity motions, as well as a tentative velocity gradient in the jet's direction, thus favouring the H30$\alpha$ emission to originate from the radio jet. Should this interpretation be confirmed with new observations, W75N(B)-VLA3 could represent the first protostellar radio jet for which a thermal radio recombination line has been detected.

Recent discoveries of faint active galactic nuclei (AGN) at the redshift frontier have revealed a plethora of broad \Halpha emitters with optically red continua, named Little Red Dots (LRDs), which comprise 15-30\% of the high redshift broad line AGN population. Due to their peculiar spectral properties and X-ray weakness, modeling LRDs with standard AGN templates has proven challenging. In particular, the validity of single-epoch virial mass estimates in determining the black hole (BH) masses of LRDs has been called into question, with some models claiming that masses might be overestimated by up to 2 orders of magnitude, and other models claiming that LRDs may be entirely stellar in nature. We report the direct, dynamical BH mass measurement in a strongly lensed LRD at $z = 7.04$. The combination of lensing with deep spectroscopic data reveals a rotation curve that is inconsistent with a nuclear star cluster, yet can be well explained by Keplerian rotation around a point mass of 50 million Solar masses, consistent with virial BH mass estimates from the Balmer lines. The Keplerian rotation leaves little room for any stellar component in a host galaxy, as we conservatively infer $M_{\rm BH}/M_{*}>2$. Such a ''naked'' black hole, together with its near-pristine environment, indicates that this LRD is a massive black hole seed caught in its earliest accretion phase.

Recent observations have confirmed that a significant fraction of the coronal Alfvenic wave spectrum originates in the photosphere. These waves travel from the photosphere to the corona, overcoming the barriers of reflection and dissipation posed by the chromosphere. Previous studies have theoretically calculated the chromospheric reflection, transmission, and absorption coefficients for pure Alfven waves under the assumption of stationary propagation. Here, we relax that assumption and investigate the time-dependent propagation of Alfven waves driven at the photosphere. Using an idealized chromospheric background model, we compare the coefficients obtained from time-dependent simulations with those derived under the stationary approximation. Additionally, we examine the impact of the spatial resolution in the numerical simulations. Considering a spatial resolution of 250 m, we find that the time-dependent transmission coefficient converges to the stationary value across the entire frequency range after only a few chromospheric Alfven crossing times, while the reflectivity displays a good convergence for frequencies lower than 30 mHz. The absorption coefficient also converges for wave frequencies above 1 mHz, for which chromospheric dissipation is significant. In contrast, at lower frequencies, wave energy dissipation is weak and the time-dependent simulations typically overestimate the absorption. Inadequate spatial resolution artificially enhances the chromospheric reflectivity, reduces wave transmission to the corona, and poorly describes the wave energy absorption. Overall, the differences between the stationary and time-dependent approaches are only minor and gradually decrease as spatial resolution and simulation time increase, which reinforces the validity of the stationary approximation.

In high-energy and astroparticle physics, event generators play an essential role, even in the simplest data analyses. As analysis techniques become more sophisticated, e.g. based on deep neural networks, their correct description of the observed event characteristics becomes even more important. Physical processes occurring in hadronic collisions are simulated within a Monte Carlo framework. A major challenge is the modeling of hadron dynamics at low momentum transfer, which includes the initial and final phases of every hadronic collision. Phenomenological models inspired by Quantum Chromodynamics used for these phases cannot guarantee completeness or correctness over the full phase space. These models usually include parameters which must be tuned to suitable experimental data. Until now, event generators have primarily been developed and tuned based on data from high-energy physics experiments at accelerators. However, in many cases they have been found to not satisfactorily describe data from astroparticle experiments, which provide sensitivity especially to hadrons produced nearly parallel to the collision axis and cover center-of-mass energies up to several hundred TeV, well beyond those reached at colliders so far. In this report, we address the complementarity of these two sets of data and present a road map for exploiting, for the first time, their complementarity by enabling a unified tuning of event generators with accelerator-based and astroparticle data.

With its third data release (DR3), Gaia begins unveiling dormant candidate compact object (CO) binaries with luminous companion (LC) as predicted by several past theoretical studies. To date, 3 black hole (BH), 21 neutron star (NS), and ~3200 white dwarf (WD) candidates have been identified with LCs in detached orbits using astrometry. We adopt an observationally motivated sampling scheme for the star formation history of the Milky Way, and initial zero-age main-sequence binary properties, incorporate all relevant binary interaction processes during evolution to obtain a realistic present-day intrinsic population of CO--LC binaries. We apply Gaia's selection criteria to identify the CO--LC binaries detectable using the observational cuts applicable for DR3 as well as its end-of-mission (EOM). We find that under the DR3 selection cuts, our detectable population includes no BH--LCs, approximately 10-40 NS--LCs, and around ~4300 WD--LCs. In contrast, by EOM, the expected numbers increase to 30-300 BH--LCs, 1500-5000 NS--LCs, and ~10^5-10^6 WD--LC binaries, primarily because of the significantly longer baseline of observation.

Lyman-$\alpha$ damping wings towards quasars are a highly sensitive probe of the neutral hydrogen (HI) content in the foreground intergalactic medium (IGM), not only constraining the global timing of reionization but also the \textit{local} ionization topology near the quasar. Near-optimal extraction of this information is possible with the help of two recently introduced reionization model-independent summary statistics of the HI distribution in the IGM \textit{before} the quasar started shining, complemented with the quasar's lifetime encoding the effect of its ionizing radiation as a third parameter. We introduce a fully Bayesian JAX-based Hamiltonian Monte Carlo (HMC) inference framework that allows us to jointly reconstruct the quasar's unknown continuum and constrain these local damping wing statistics. We put forward a probabilistic framework that allows us to tie these local constraints to any specific reionization model and obtain model-dependent constraints on the global timing of reionization. We demonstrate that we are able to constrain the (Lorentzian-weighted) HI column density in front of the quasar to a precision of $0.69_{-0.30}^{+0.06}\,\mathrm{dex}$ and its original distance to the first neutral patch before the quasar started shining to $31.4_{-28.1}^{+10.7}\,\mathrm{cMpc}$ (if a noticeable damping wing is present in the spectrum), extracting hitherto unused local information from the IGM damping wing imprint. Once tied to a specific reionization model, we find that the statistical fidelity of our constraints on the global IGM neutral fraction and the lifetime of the quasar improves, while retaining the same precision as achieved by pipelines that infer these parameters directly.

Thus far, Lyman-$\alpha$ damping wings towards quasars have been used to probe the \textit{global} ionization state of the foreground intergalactic medium (IGM). A new parameterization has demonstrated that the damping wing signature also carries \textit{local} information about the distribution of neutral hydrogen (HI) in front of the quasar before it started shining. Leveraging a recently introduced Bayesian \texttt{JAX}-based Hamiltonian Monte Carlo (HMC) inference framework, we derive constraints on the Lorentzian-weighted HI column density $N_\mathrm{HI}^\mathrm{DW}$, the quasar's distance $r_\mathrm{patch}$ to the first neutral patch and its lifetime $t_\mathrm{Q}$ based on JWST/NIRSpec spectra of the two $z \sim 7.5$ quasars J1007+2115 and J1342+0928. After folding in model-dependent topology information, we find that J1007+2115 (and J1342+0928) is most likely to reside in a $\langle x_\mathrm{HI} \rangle = 0.32_{-0.20}^{+0.22}$ ($0.58_{-0.23}^{+0.23}$) neutral IGM while shining for a remarkably short lifetime of $\log_{10} t_\mathrm{Q} /\mathrm{yr} = 4.14_{-0.18}^{+0.74}$ (an intermediate lifetime of $5.64_{-0.43}^{+0.25}$) along a sightline with $\log_{10} N_\mathrm{HI}^\mathrm{DW} /\mathrm{cm}^{-2} = 19.70_{-0.86}^{+0.35}$ ($20.24_{-0.22}^{+0.25}$) and $r_\mathrm{patch} = 28.9_{-14.4}^{+54.0} \,\mathrm{cMpc}$ ($10.9_{-5.9}^{+5.6} \,\mathrm{cMpc}$). In light of the potential presence of local absorbers in the foreground of J1342+0928 as has been recently suggested, we also demonstrate how the Lorentzian-weighted column density $N_\mathrm{HI}^\mathrm{DW}$ provides a natural means for quantifying their contribution to the observed damping wing signal.

In cosmology, correlation functions on a late-time boundary can arise from both field redefinitions and bulk interactions, which are usually believed to generate distinct results. In this letter, we propose a counterexample showcasing that correlators from local field redefinitions can be identical to the ones from bulk interactions. In particular, we consider a two-field model in de Sitter space, where the field space gets twisted by field redefinitions to yield a nontrivial reheating surface. We then exploit conformal symmetry to compute the three-point function, and show that the result takes the form of contact correlators with a total-energy singularity. Our finding suggests that in the effective field theory, a class of lower-dimensional operators, which were overlooked previously, may lead to nontrivial signals in cosmological correlators. As an illustration, we apply our result to cosmic inflation and derive a possibly leading signature of the Higgs in the primordial bispectrum.

As recently proposed, a non-vanishing topological angle may play a central role in QCD-like theories of dark matter (DM). In this work, we introduce a dark photon portal to the Standard Model in order to establish thermal equilibrium in the early Universe, and discuss the ensuing phenomenological constraints, including the stability of DM. The resulting dynamics accounts for the observed DM relic abundance and yields velocity-dependent DM self-interactions in astrophysical halos. Due to the sharp velocity dependence arising from a Breit-Wigner resonance, dedicated studies are required to assess the gravothermal evolution in detail, especially in the core-collapse regime. This is particularly timely in light of self-interacting DM interpretations of strong-lensing systems such as SDSS J0946+1006, which can be naturally explained within our framework.

We present version 2.1 of the public code {\sc precession}, a Python module for studying the post-Newtonian dynamics of precessing black hole binaries. In this release, we extend the code to handle eccentric orbits. This extension leverages the existing numerical infrastructure wherever possible, introducing a semi-automatic method to adapt circular-orbit functions to the eccentric case via a Python decorator. Additional new features include orbit- and precession-averaged evolutionary equations for the eccentricity, as well as revised expressions to convert between post-Newtonian separation and gravitational-wave emission frequency.

Recent work has shown the possibility of detecting dense dark-matter distributions surrounding intermediate or extreme mass-ratio inspirals through gravitational waves using LISA. Modeling these systems requires evolving the coupled dynamics of the binary and the dark matter. This also requires setting reasonable initial conditions for the dark-matter distribution, which itself relies upon understanding the formation history of these systems. In this paper, we investigate how two aspects of these systems' formation histories shape the dark-matter distribution: accretion onto the primary and prior merger events. We model accretion by introducing a minimum allowed angular momentum of dark-matter particles, which removes such particles that would have been accreted by the primary. When simulating an inspiral within such a distribution, we find a smaller dephasing of the gravitational-wave signal from a vacuum binary as compared to an inspiral without such a cutoff, particularly for more extreme mass-ratios. We also simulate an inspiral which takes place within a dark-matter distribution that remains after a prior merger. We find that the decrease in dephasing from vacuum binaries when compared to the prior inspiral is most significant for less extreme mass-ratios. Nevertheless, the environmental effects from the dark matter for these different cases of initial data are still expected to be measurable by future space-based detectors.

This article introduces nox-minima, a low-cost, three-dimensional paper dome that provides an alternative representation of the sky for astronomy education. Generated from precise astronomical data, the dome provides accurate local sky views for any date and location. Its assembly is simple, and the design is freely available at this http URL . Initial workshops with students and teachers confirm its effectiveness as a hands-on tool to explore the celestial sphere and cultural perspectives on the sky.

We investigate the physical and observational features of static, spherically symmetric black hole spacetimes surrounded by anisotropic fluid and embedded in a plasma environment. Motivated by recent advances in black hole imaging and precision measurements in strong gravity, we explore light propagation, wave dynamics, and observational signatures in such geometries. We begin by analyzing the background spacetime and matter content, examining the horizon structure and verifying the energy conditions associated with the anisotropic fluid. We then study photon trajectories in both vacuum and plasma environments, deriving the equations of motion and computing deflection angles and image magnifications under weak gravitational lensing. Both uniform and power-law plasma profiles are considered to model realistic astrophysical settings. In the wave optics regime, we first analyze the linear stability of the spacetime under axial (odd-parity) perturbations using Chandrasekhar's method, and then investigate scalar field scattering by solving the wave equation in the curved background with plasma. Using Born and WKB approximations, we compute the differential scattering cross-sections and examine how anisotropy and plasma affect interference features. Finally, we perform parameter estimation using Markov Chain Monte Carlo methods to constrain the black hole mass and anisotropic fluid parameters, utilizing EHT and GRAVITY data for Sgr A* and EHT-only data for M87*. These results present a unified theoretical framework that links anisotropic matter effects with lensing and scattering observables providing a firm basis for future comparisons with high-resolution astrophysical data sets in diverse contexts.

Magnetic Rayleigh-Taylor instability (MRTI) governs material transport and mixing in astrophysical and laboratory plasmas under the influence of gravity and magnetic fields. While magnetic reconnection is known to occur during MRTI evolution, its role in the evolution and energy dynamics remains poorly understood. Here, we present a comprehensive analysis of the role of reconnection in the two-dimensional MRTI dynamics, using high-resolution simulations. We establish that reconnection, through facilitating plume merger, relieving magnetic tension, and enabling continued instability growth, forms an essential component for the long-term instability evolution. To quantify the role of reconnection in energy dynamics, we develop a robust automated reconnection detection algorithm and perform a statistical analysis across a range of magnetic field strengths. We find that reconnection accounts for up to $80\%$ of the magnetic-to-kinetic energy transfer in the weak magnetic field regime, while contributing minimally ($\approx 3\%$) to magnetic energy dissipation. Our results establish magnetic reconnection as a critical mechanism that regulates large-scale MRTI dynamics, with implications for astrophysical plasmas and turbulent mixing in magnetized flows.

During a solar flare, the fluxes in various lines and continua of the solar spectrum increase, leading to enhanced ionization of the illuminated part of the Earth's ionosphere and an increase in the total electron content (TEC). It has been previously shown that nearly 50% of X-class solar flares exhibit a second peak in warm coronal lines, such as FeXV and FeXVI (called the 'EUV late phase'), the effect of which on the ionosphere remains largely unexplored. This study presents an analysis of the ionospheric response to 14 X-class flares with pronounced late phases. For the first time, empirical relationships between the increase in TEC and the solar flux enhancement during the impulsive and late phases of the flare are derived. Additionally, we demonstrate the influence of flare location on the intensity of geoeffective solar spectral lines and the ratio of the ionospheric responses to the impulsive and late phases of solar flares.

We summarize how a renormalization-group (RG)-consistent treatment removes well-known artifacts in NJL-model descriptions of color-superconducting quark matter. We introduce two RG-consistent schemes, "minimal" and "massless", and present analytic solutions for the diquark gap at $T=0$ and for the phase boundary $T_c(\mu)$ in symmetric massless matter, representing the high-density limit of the model. We compare the pairing gaps, phase diagram, and speed of sound with results obtained using conventional regularization.

We conduct a systematic investigation of the influence of the nuclear symmetry energy on the proposed neutron decay into dark matter particles within the cores of neutron stars. Unlike the majority of previous studies that considered only pure neutron matter, the present analysis is extended to encompass $\beta$-stable nuclear matter. Furthermore, in relation to previous studies, the interactions between dark matter and baryons are incorporated and systematically studied regarding their effect on the structure of neutron stars. Our findings indicate that the nuclear symmetry energy plays a critical role in shaping the total equation of state (EoS) for dense neutron star matter containing dark sector components. The strength of interactions among dark matter particles, as well as between dark matter and baryons, is shown to be pivotal in determining both the composition and the macroscopic properties of neutron stars. The concurrent tuning of interaction strengths alongside the symmetry energy parameters may facilitate a more accurate reproduction of recent observational data relevant to neutron star properties. In any case, the extent to which the proposed dark decay of the neutron is affected by the extreme conditions prevailing in the interior of neutron stars remains an open problem.

Introduction to the theoretical foundations of gravitational waves: from general relativity to detection and binary system waveforms. Lecture notes prepared for the MaNiTou summer school on gravitational waves. Draft chapter for the CNRS contemporary Encyclopaedia Sciences to be published by ISTE.