Papers for Thursday, Mar 07 2024

Radio-mode feedback associated with the active galactic nuclei (AGN) at the cores of galaxy clusters injects large amount of energy into the intracluster medium (ICM), offsetting radiative losses through X-ray emission. This mechanism prevents the ICM from rapidly cooling down and fueling extreme starburst activity as it accretes onto the central galaxies, and is therefore a key ingredient in the evolution of galaxy clusters. However, the influence and mode of feedback at high redshifts (z~1) remains largely unknown. Low-frequency sub-arcsecond resolution radio observations taken with the International LOFAR Telescope have demonstrated their ability to assist X-ray observations with constraining the energy output from the AGNs (or "cavity power") in galaxy clusters, thereby enabling research at higher redshifts than before. In this pilot project, we test this hybrid method on a high redshift (0.6<z<1.3) sample of 13 galaxy clusters for the first time with the aim of verifying the performance of this method at these redshifts and providing the first estimates of the cavity power associated with the central AGN for a sample of distant clusters. We were able to detect clear radio lobes in three out of thirteen galaxy clusters at redshifts 0.7<z<0.9, and use these detections in combination with ICM pressures surrounding the radio lobes obtained from standard profiles to calculate the corresponding cavity powers of the AGNs. By combining our results with the literature, the current data appear to suggest that the average cavity power peaked at a redshift of z~0.4 and slowly decreases toward higher redshifts. However, we require more and tighter constraints on the cavity volume and a better understanding of our observational systematics to confirm any deviation of the cavity power trend from a constant level.

We present an analysis of the diffuse ionised gas (DIG) in a high-resolution simulation of an isolated Milky Way-like galaxy, incorporating on-the-fly radiative transfer and non-equilibrium thermochemistry. We utilise the Monte-Carlo radiative transfer code COLT to self-consistently obtain ionisation states and line emission in post-processing. We find a clear bimodal distribution in the electron densities of ionised gas ($n_{\rm e}$), allowing us to define a threshold of $n_{\rm e}=10\,\mathrm{cm}^{-3}$ to differentiate DIG from HII regions. The DIG is primarily ionised by stars aged 5-25 Myr, which become exposed directly to low-density gas after HII regions have been cleared. Leakage from recently formed stars ($<5$ Myr) is only moderately important for DIG ionisation. We forward model local observations and validate our simulated DIG against observed line ratios in [SII]/H$\alpha$, [NII]/H$\alpha$, [OI]/H$\alpha$, and [OIII]/H$\beta$ against $\Sigma_{\rm H\alpha}$. The mock observations not only reproduce observed correlations, but also demonstrate that such trends are related to an increasing temperature and hardening ionising radiation field with decreasing $n_{\rm e}$. The hardening of radiation within the DIG is caused by the gradual transition of the dominant ionising source with decreasing $n_{\rm e}$ from 0 Myr to 25 Myr stars, which have progressively harder intrinsic ionising spectra primarily due to the extended Wolf-Rayet phase caused by binary interactions. Consequently, the DIG line ratio trends can be attributed to ongoing star formation, rather than secondary ionisation sources, and therefore present a potent test for stellar feedback and stellar population models.

The JWST has ushered in a new era in atmospheric characterisations of temperate low-mass exoplanets with recent detections of carbon-bearing molecules in the candidate Hycean world K2-18 b. We investigated JWST observations of the TOI-270 system, with two sub-Neptunes simultaneously transiting the nearby M dwarf during the visit. We report our atmospheric characterisation of the outer planet TOI-270 d, a candidate Hycean world, with JWST transmission spectroscopy using the NIRSpec G395H instrument in the 2.7-5.2 $\mu$m range, combined with previous observations obtained with the HST WFC3 spectrograph (1.1-1.6 $\mu$m). The spectrum reveals strong signatures of CH4 and CO2 at 3.8-4.9$\sigma$ and 2.9-3.9$\sigma$ confidence, respectively, and no evidence of NH3. The abundant CH4 and CO2, at ~0.1-1% mixing ratios, and the non-detection of NH3 are similar to the findings reported for K2-18 b and consistent with predictions for a Hycean world with a planet-wide ocean under a H2-rich atmosphere. We also report evidence of CS2 at a 2.3-3.0$\sigma$ confidence and a potential inference of H2O at 1.6-4.4$\sigma$, depending on the data analysis approach, and discuss possible interpretations of these results. The spectrum does not provide strong constraints on the presence of clouds or hazes in the observable atmosphere, nor any evidence for the effects of stellar heterogeneities, which is consistent with previous studies. For the smaller inner planet TOI-270 b, we find that the spectrum is inconsistent with a featureless spectrum at ~3$\sigma$, showing some preference for an H2-rich atmosphere in a super-Earth. We discuss the implications of our findings and future prospects.

Multimessenger signals from binary neutron star (BNS) mergers are promising tools to infer the largely unknown properties of nuclear matter at densities that are presently inaccessible to laboratory experiments. The gravitational waves (GWs) emitted by BNS merger remnants, in particular, have the potential of setting tight constraints on the neutron-star equation of state (EOS) that would complement those coming from the late inspiral, direct mass-radius measurements, or ab-initio dense-matter calculations. To explore this possibility, we perform a representative series of general-relativistic simulations of BNS systems with EOSs carefully constructed so as to cover comprehensively the high-density regime of the EOS space. From these simulations, we identify a novel and tight correlation between the ratio of the energy and angular-momentum losses in the late-time portion of the post-merger signal, i.e., the "long ringdown", and the properties of the EOS at the highest pressures and densities in neutron-star cores. When applying this correlation to post-merger GW signals, we find a significant reduction of the EOS uncertainty at densities several times the nuclear saturation density, where no direct constraints are currently available. Hence, the long ringdown has the potential of providing new and stringent constraints on the state of matter in neutron stars in general and, in particular, in their cores.

The three-body problem (3BP) poses a longstanding challenge in physics and celestial mechanics. Despite the impossibility of obtaining general analytical solutions, statistical theories have been developed based on the ergodic principle. This assumption is justified by chaos, which is expected to fully mix the accessible phase space of the 3BP. This study probes the presence of regular (i.e. non chaotic) trajectories within the 3BP and assesses their impact on statistical escape theories. Using numerical simulations, we establish criteria for identifying regular trajectories and analyse their impact on statistical outcomes. Our analysis reveals that regular trajectories occupy up to 32% of the phase space, and their outcomes defy the predictions of statistical escape theories. The coexistence of regular and chaotic regions at all scales is characterized by a multi-fractal behaviour. Integration errors manifest as numerical chaos, artificially enhancing the mixing of the phase space and affecting the reliability of individual simulations, yet preserving the statistical correctness of an ensemble of realizations. Our findings underscore the challenges in applying statistical escape theories to astrophysical problems, as they may bias results by excluding the outcome of regular trajectories. This is particularly important in the context of formation scenarios of gravitational wave mergers, where biased estimates of binary eccentricity can have significant consequences.

Asteroid collisions are one of the main processes responsible for the evolution of bodies in the main belt. Using observations of the Dimorphos impact by the DART spacecraft, we estimate how asteroid collisions in the main belt may look in the first hours after the impact. If the DART event is representative of asteroid collisions with a ~1m size impactor, then the light curves of these collisions will rise on time scales of about >100s and will remain bright for about one hour. Next, the light curve will decay on a few hours time scale to an intermediate luminosity level in which it will remain for several weeks, before slowly returning to its baseline magnitude. This estimate suffers from several uncertainties due to, e.g., the diversity of asteroid composition, their material strength, and spread in collision velocities. We estimate that the rate of collisions in the main belt with energy similar or larger than the DART impact is of the order of 7000 per year (+/-1dex). The large range is due to the uncertainty in the abundance of ~1-m size asteroids. We estimate the magnitude distribution of such events in the main belt, and we show that ~6% of these events may peak at magnitudes brighter than 21. The detection of these events requires a survey with <1hr cadence and may contribute to our understanding of the asteroids' size distribution, collisional physics, and dust production. With an adequate survey strategy, new survey telescopes may regularly detect asteroid collisions.

The surface [C/N] ratios of evolved giants are strongly affected by the first dredge-up (FDU) of nuclear-processed material from stellar cores. C and N also have distinct nucleosynthetic origins and serve as diagnostics of mixing and mass loss. We use subgiants to find strong trends in the birth [C/N] with [Fe/H], which differ between the low-$\alpha$ and high-$\alpha$ populations. We demonstrate that these birth trends have a strong impact on the surface abundances after the FDU. This effect is neglected in current stellar models, which use solar-scaled C and N. We map out the FDU as a function of evolutionary state, mass, and composition using a large and precisely measured asteroseismic dataset in first-ascent red giant branch (RGB) and core He-burning, or red clump (RC), stars. We describe the domains where [C/N] is a useful mass diagnostic and find that the RC complements the RGB and extends the range of validity to higher mass. We find evidence for extra mixing on the RGB below [Fe/H]= -0.4, matching literature results, for high-$\alpha$ giants, but there is no clear evidence of mixing in the low-$\alpha$ giants. The predicted signal of mass loss is weak and difficult to detect in our sample. We discuss implications for stellar physics and stellar population applications.

We study the dynamics of a star orbiting a merging black-hole binary (BHB) in a coplanar triple configuration. During the BHB's orbital decay, the system can be driven across the apsidal precession resonance, where the apsidal precession rate of the stellar orbit matches that of the inner BHB. As a result, the system gets captured into a state of resonance advection until the merger of the BHB, leading to an extreme eccentricity growth of the stellar orbit. This resonance advection occurs when the inner binary has a non-zero eccentricity and unequal masses. The resonant driving of the stellar eccentricity can significantly alter the hardening rate of the inner BHB, and produce observational signatures to uncover the presence of nearby merging or merged BHBs.

We investigated the properties of 94 [NeV]3426AA-selected type 2 AGN in COSMOS at z=0.6-1.2, performing optical-to-far-infrared spectral energy distribution fitting. In addition, we analyze the X-ray spectra of the X-ray-detected sources to obtain reliable values of the AGN obscuration and intrinsic luminosity. We found that more than two-thirds of our sample is composed of very obscured sources, with about 20% of the sources being candidate CT-AGN and half being AGNs in a strong phase of accretion. With respect to non-active galaxies, we find a higher fraction of sources within the main sequence and little evidence for AGNs quenching the SF. The comparison with the prediction from the in situ co-evolution model suggests that [NeV] is an effective tool for selecting galaxies in the obscured growth phase of the BH-galaxy co-evolution paradigm. We find that the "quenching phase" is still to come for most of the sample and only few galaxies show evidence of quenched SF activity.

Strong gravitational lensing provides a purely gravitational means to infer properties of dark matter halos and thereby constrain the particle nature of dark matter. Strong lenses sometimes appear as four lensed images of a background quasar accompanied by spatially-resolved emission from the quasar host galaxy encircling the main deflector (lensed arcs). We present methodology to simultaneously reconstruct lensed arcs and relative image magnifications (flux ratios) in the presence of full populations of dark matter subhalos and line-of-sight halos. To this end, we develop a new approach for multi-plane ray tracing that accelerates lens mass and source light reconstruction by factors of $\sim 100-1000$. Using simulated data with a cold dark matter (CDM) ground truth, we show that simultaneous reconstruction of lensed arcs and flux ratios isolates small-scale perturbations to flux ratios by dark matter substructure from uncertainties associated with the main deflector mass profile on larger angular scales. Relative to analyses that use only image positions and flux ratios to constrain the lens model, incorporating arcs strengthens likelihood ratios penalizing warm dark matter (WDM) with a characteristic suppression scale $m_{\rm{hm}} / M_{\odot}$ in the range $\left[10^7 - 10^{7.5}\right]$, $\left[10^{7.5} - 10^{8}\right]$, $\left[10^8 - 10^{8.5}\right]$, $\left[10^{8.5} - 10^{9}\right]$ by factors of $1.3$, $2.5$, $5.6$, and $13.1$, respectively, and the $95\%$ exclusion limit improves by 0.5 dex in $\log_{10} m_{\rm{hm}}$. The enhanced sensitivity to low-mass halos enabled by these methods pushes the observational frontier of substructure lensing to the threshold of galaxy formation, enabling stringent tests of any theory that alters the properties of dark matter halos.

The Galaxy inner parts are generally considered to be optically symmetric, as well as kinematically symmetric for most massive early-type galaxies. At the lower-mass end, many galaxies contain lots of small patches in their velocity maps, causing their kinematics to be nonsmooth in small scales and far from symmetry. These small patches can easily be mistaken for measurement uncertainties and have not been well discussed. We used the comparison of observations and numerical simulations to demonstrate the small patches existence beyond uncertainties. For the first time we have found that the fluctuation degrees have an approximate inverse loglinear relation with the galaxy stellar surface mass densities. This tight relation among galaxies that do not show obvious optical asymmetry that traces environmental perturbations indicates that stellar motion in galaxies has inherent asymmetry besides external environment influences. The degree of the kinetic asymmetry is closely related to and constrained by the intrinsic properties of the host galaxy.

The stellar kinematics of low-mass galaxies are usually observed to be very unsmooth with significant kinematical fluctuations in small scales, which cannot be consistent with the projected centrosymmetric stellar kinematics obtained from commonly used dynamical models. In this work, we aim to test whether the high degree of kinematical fluctuations affects the dynamical mass estimate of galaxies. We use the asymmetry parameter $\eta$ obtained from the $180^{\circ}$ rotation self-subtraction of stellar kinematics of galaxies to quantify the degree of kinematical small-scale fluctuations. We use TNG50 numerical simulation to construct a large sample of mock galaxies with known total masses, and then obtained the virial dynamical mass estimator of these mock galaxies. We find that the dynamical masses within three-dimensional $R_{\rm e}$ to the mock galaxy centres are overall averagely accurate within around 0.1 dex under the symmetric assumption, while $R_{\rm e}$ means the projected circularized half-stellar mass radius in this work. We study the local virial mass estimation bias for mock galaxies of different $\eta$. The maximum bias difference of two $\eta$ bins is around 0.16 dex, which with other local biases may help apply the observational virial mass estimators obtained from massive galaxies to other types of galaxies. We find that the Spearman's $\rho$ of $\eta$ with the intrinsic mass estimation deviations is near zero if the local bias is eliminated properly. The results indicate that even for low-mass galaxies, the existence of high degree of kinematical small-scale fluctuations does not affect the measurement of the dynamical mass of galaxies.

Within the first few hundreds of millions of years, many physical processes sculpt the eventual properties of young planets. NASA's TESS mission has surveyed young stellar associations across the entire sky for transiting planets providing glimpses into the various stages of planetary evolution. Using our own detection pipeline, we search a magnitude-limited sample of 7219 young stars ($\leq$200 Myr) observed in the first four years of TESS for small (2-8 R$_\oplus$), short period (1.6-20 days) transiting planets. The completeness of our survey is characterized by a series of injection and recovery simulations. Our analysis of TESS 2-minute cadence and Full Frame Image (FFI) light curves recover all known TOIs, as well as four new planet candidates not previously identified as TOIs. We derive an occurrence rate of $35^{+13}_{-10}$% for mini-Neptunes and $27^{+10}_{-8}$% for super-Neptunes from the 2-minute cadence data, and $22^{+8.6}_{-6.8}$% for mini-Neptunes and $13^{+3.9}_{-4.9}$% for super-Neptunes from FFI data. To independently validate our results, we compare our survey yield with the predicted planet yield assuming Kepler planet statistics. We consistently find a mild increase in the occurrence of super-Neptunes and a significant increase in the occurrence of Neptune-sized planets with orbital periods of 6.2-12 days when compared to their mature counterparts. The young planet distribution from our study is most consistent with evolution models describing the early contraction of hydrogen-dominated atmospheres undergoing atmospheric escape and inconsistent with heavier atmosphere models offering only mild radial contraction early on.

We exploit the astro-photometric dataset of the multi-epoch infrared parallel field of a $\textit{Hubble Space Telescope}$ Large Programme aimed at studying the faintest stars of the globular cluster NGC$\,$6752 to determine the luminosity and mass functions of the multiple stellar populations of this cluster. Thanks to the measurement of proper motions and deeper completeness, the results presented in this paper represent a significant improvement over those of previous studies. We successfully derived membership probabilities reaching stars as faint as $m_{\rm F160W} \sim 25$, allowing us to reliably distinguish the three main stellar populations detected within this cluster. We employed a new set of model isochrones that have been individually fit to the colour-magnitude diagram of each population. We present a comprehensive analysis of the luminosity and mass functions for three stellar populations within NGC$\,$6752. Notably, our findings reveal differences in the present-day luminosity and mass functions of first-generation and second-generation stars; these differences are consistent with the manifestation of the effects of dynamical processes acting on populations with different initial spatial distributions. Finally, we publicly release the catalogues with positions, photometry, proper motions, and memberships probabilities, as well as the stacked-image atlases and all newly calculated stellar models.

The standardizable nature of gravitationally lensed Type Ia supernovae (glSNe Ia) makes them an attractive target for time delay cosmography, since a source with known luminosity breaks the mass sheet degeneracy. It is known that microlensing by stars in the lensing galaxy can add significant stochastic uncertainty to the unlensed luminosity which is often much larger than the intrinsic scatter of the Ia population. In this work, we show how the temporal microlensing variations as the supernova disc expands can be used to improve the standardization of glSNe Ia. We find that SNe are standardizable if they do not cross caustics as they expand. We estimate that this will be the case for $\approx$6 doubly imaged systems and $\approx$0.3 quadruply imaged systems per year in LSST. At the end of the ten year LSST survey, these systems should enable us to test for systematics in $H_0$ due to the mass sheet degeneracy at the $1.00^{+0.07}_{-0.06}$\% level, or $1.8\pm0.2$\% if we can only extract time delays from the third of systems with counter images brighter than $i=24$ mag.

Context. Gamma Ray Bursts (GRBs) can be detected at cosmological distances and therefore can be used to study the contents and phases of the early Universe. The 4 -- 150 keV wide-field trigger camera ECLAIRs to fly on-board the Space-based multi-band Variable Object Monitor (SVOM) mission dedicated to study high-energy transient sky in synergy with multi-messenger follow-up instruments, is adapted to detect high-z GRBs. Aims. Investigating the detection capabilities of ECLAIRs for high redshift GRBs and estimating the impacts of instrumental biases in reconstructing some of the source measured properties, focusing on GRB duration biases as a function of redshift. Methods. We simulated realistic detection scenarios for a sample of 162 already observed GRBs with known redshift values as they would have been seen by ECLAIRs. We simulated them at redshift values equal and higher than their measured value. Then, we assessed whether they would be detected with a trigger algorithm resembling that on-board of ECLAIRs, and derived some quantities such as T90 for those that would have been detected. Results. We find that ECLAIRs would be capable of detecting GRBs up to very high redshift values (e.g. 20 GRBs of our sample are detectable within more than 0.4 of the ECLAIRs Field of View for z > 12). The ECLAIRs low-energy threshold of 4 keV, contributes to this great detection capability, as it may enhance it at high redshift (z > 10) by over 10% compared to a 15 keV low-energy threshold. We have also shown that the detection of GRBs at high-z values may imprint tip-of-the-iceberg biases on the GRB duration measurements, which can affect the reconstruction of other source properties.

Mass loss at the asymptotic giant branch (AGB) plays an important role not only in the final fates of stars, but also in the chemical evolution of galaxies. Nevertheless, the metallicity effects on AGB mass loss are not yet fully understood. We present spatially resolved observations of an AGB star, V3, in the metal-poor globular cluster 47 Tuc (NGC 104). The AGB star 47 Tuc V3 was observed using the GRAVITY instrument at ESO's Very Large Telescope Interferometer (VLTI) at 2-2.45 micron with a projected baseline length of up to 96 m. The object 47 Tuc V3 has been spatially resolved and stands as the first to attempt to spatially resolve an individual star in a globular cluster. The uniform-disk fit to the observed data results in an angular diameter of ~0.7 mas. Our modeling of the spectral energy distribution and near-infrared interferometric GRAVITY data suggests that the observed data can be explained by an optically thin dust shell with a 0.55 micron optical depth of 0.05-0.25, consisting of metallic iron grains, likely together with effects of the extended atmosphere of the central star. The dust temperature at the inner shell boundary is 500-800 K (corresponding to 23-90 stellar radii), significantly lower than observed in nearby oxygen-rich AGB stars. Radiation pressure on small (< 0.05 micron) iron grains is not sufficient to drive stellar winds. Therefore, iron grains may grow to larger sizes, even in the metal-poor environment. Alternatively, it is possible that the observed iron grain formation is a result of the mass outflow initiated by some other mechanism(s). The sensitivity and angular resolution of VLTI provides a new window onto spatially resolving individual stars in metal-poor globular clusters. This allows us to improve subsequent studies of the metallicity dependence of dust formation and mass loss.

We discuss new techniques and ideas in mm-wave instrumentation that can be used in CMB (Cosmic Microwave background) polarization experiments. Novel techniques in antenna receiver, beam combining and detector systems have resulted in greatly improved sensitivities. We present a few promising approaches and discuss briefly plans for feasibility studies for detecting CMB polarization foregrounds and signal.

We study the origin of the positron excess observed in the local cosmic-ray spectrum at high energies, and relate it to the cosmic rays and gamma-ray emission across the entire Galaxy. In particular, we explore the hypothesis of a single, dominant source accountable for primary electron-positron pairs. Since we are agnostic about the physical nature of the underlying source population, we consider four simple models that are representative of young pulsars, old stars (as a tracer of millisecond pulsars), and annihilating dark matter particles. In the dark matter hypothesis, we consider both a cored and a cuspy model for the halo in the Milky Way. Then, we compare the associated gamma-ray sky maps with Fermi-LAT data. The aim of this work is not to derive constraints or upper limits for the different models considered, but rather to explore the possibility, as a proof of concept, of building a self-consistent model able to explain simultaneously the origin of all cosmic-ray species, including positrons, as well as the Galactic center GeV gamma-ray emission. We find that the emission arising from pulsar wind nebulae is fairly concentrated near the mid plane, and therefore additional cosmic-ray sources must be invoked to explain the emission at the center of the Galaxy. If the local positron excess were mainly due to millisecond pulsars, inverse Compton scattering by the particles injected in the Milky Way bulge would naturally account for a non-negligible fraction of the central gamma-ray emission. The case of annihilating dark matter is very sensitive to the precise shape of the dark matter profile. The results for a standard NFW cuspy profile are above the gamma-ray measurements by as much as a factor of 2 in some regions of the Galaxy, while the results for an isothermal, cored profile are still compatible with the data. However, the cross-sections exceed the current constraints.

We verify candidate hypervelocity red clump stars located in the Galactic bulge that were selected based on the VVV and the Gaia DR2 data by Luna et al. (2019). To do so, we analyze data from the OGLE-IV survey: difference images and astrometric time series. We have data for 30 stars out of 34 hypervelocity candidates. We confirmed high proper motion of only one of these stars and find out that it is a nearby one, hence, not hypervelocity. To sum up, we do not confirm the candidate stars as hypervelocity ones. Hence, we disprove the production rate of hypervelocity red clump stars by the central supermassive black hole provided by Luna et al. (2019).

Even though sub-Neptunes likely represent the most common outcome of planet formation, their natures remain poorly understood. In particular, planets near 1.5-2.5$\,R_\oplus$ often have bulk densities that can be explained equally well with widely different compositions and interior structures, resulting in grossly divergent implications for their formation. Here, we present the full 0.6-5.2$\,\mu \mathrm{m}$ JWST NIRISS/SOSS+NIRSpec/G395H transmission spectrum of the 2.2$\,R_\oplus$ TOI-270d ($4.78\,M_\oplus$, $T_\mathrm{eq}$=350-380 K), delivering unprecedented sensitivity for atmospheric characterization in the sub-Neptune regime. We detect five vibrational bands of CH$_4$ at 1.15, 1.4, 1.7, 2.3, and 3.3$\,\mu$m (9.4$\sigma$), the signature of CO$_2$ at 4.3$\,\mu$m (4.8$\sigma$), water vapor (2.5$\sigma$), and potential signatures of SO$_2$ at 4.0$\,\mu \mathrm{m}$ and CS$_2$ at 4.6$\,\mu\mathrm{m}$. Intriguingly, we find an overall highly metal-rich atmosphere, with a mean molecular weight of $5.47_{-1.14}^{+1.25}$. We infer an atmospheric metal mass fraction of $58_{-12}^{+8}\%$ and a C/O of $0.47_{-0.19}^{+0.16}$, indicating that approximately half the mass of the outer envelope is in high-molecular-weight volatiles (H$_2$O, CH$_4$, CO, CO$_2$) rather than H$_2$/He. We introduce a sub-Neptune classification scheme and identify TOI-270d as a "miscible-envelope sub-Neptune" in which H$_2$/He is well-mixed with the high-molecular-weight volatiles in a miscible supercritical metal-rich envelope. For a fully miscible envelope, we conclude that TOI-270d's interior is $90_{-4}^{+3}\,$wt$\,\%$ rock/iron, indicating that it formed as a rocky planet that accreted a few wt % of H$_2$/He, with the overall envelope metal content explained by magma-ocean/envelope reactions without the need for significant ice accretion. TOI-270d may well be an archetype of the overall population of sub-Neptunes.

The concept of a new space very long baseline interferometry system named the Event Horizon Imager (EHI) has been proposed to dramatically improve black hole imaging and provide precise tests of the theory of general relativity. We investigate the ability to make high-resolution movies of the black hole shadow and jet launching region around the supermassive black hole M87* and other black hole jets with a three-satellite EHI configuration. We aim to identify orbital configurations to optimize the uv-coverage to image variable sources. Observations of general relativistic magnetohydrodynamics models were simulated for the configuration, consisting of three satellites in circular medium earth orbits with an orbital plane perpendicular to the line of sight. The expected noise was based on preliminary system parameters. Movie frames, for which a part of the uv-coverage may be excessively sparse, were reconstructed with algorithms that recover missing information from other frames. Averaging visibilities accumulated over multiple epochs of observations with an appropriate orbital configuration then improves the image quality. With an enhanced signal-to-noise ratio (S/N), timescales of observed variability were decreased. Our simulations show that the EHI with standard system parameters is capable of imaging the variability in the M87* environment on event horizon scales with approximately a month-long temporal resolution. The EHI with more optimistic noise parameters (enhancing S/N about 100-fold) would allow for imaging of the variability on gravitational timescales. Observations with an EHI setup at lower frequencies are capable of imaging the variability in extended jets. The EHI concept can be used to image the variability in a black hole environment and extended jets, allowing for stronger tests of gravity theories and models of black hole accretion, plasma dynamics, and jet launching.

The scalar and tensor fluctuations produced during inflation can be correlated, if arising from the same underlying mechanism. In this paper we investigate such correlation in the model of axion inflation, where the rolling inflaton produces quanta of a $U(1)$ gauge field which, in turn, source scalar and tensor fluctuations. We compute the primordial correlator of the curvature perturbation, $\zeta$, with the amplitude of the gravitational waves squared, $h_{ij}h_{ij}$, at frequencies probed by gravitational wave detectors. This two-point function receives two contributions: one arising from the correlation of gravitational waves with the scalar perturbations generated by the standard mechanism of amplification of vacuum fluctuations, and the other coming from the correlation of gravitational waves with the scalar perturbations sourced by the gauge field. Our analysis shows that the latter effect is generally dominant. The correlator, normalized by the amplitude of $\zeta$ and of $h_{ij}h_{ij}$, turns out to be of the order of $ 10^{-2}\,\times (f_{\rm NL}^{\rm equil})^{1/3}$, where $f_{\rm NL}^{\rm equil}$ measures the scalar bispectrum sourced by the gauge modes.

The origin and early evolution of the Jovian moon Ganymede, known to have an internal ocean, have garnered considerable interest in the field of origin of satellites and life. Ganymede has an ancient impact structure, called a furrow system. The furrow system is the largest impact structures in the outer solar system and the impact should have significantly affected Ganymede's early history; however, its impact is poorly understood. Here we show that mass redistribution induced by the furrow-forming impact caused a reorientation (true polar wander) of Ganymede. The center of the furrow system is located close to the tidal axis, indicating that the impact created a positive mass anomaly that reoriented the impact site toward the tidal axis. We found that an impactor with a radius of 150 km and an incidence angle between 60 degree and 90 degree can reproduce the current location of the furrow system. Furthermore, this ejecta model is adoptable in Pluto's reorientation. Although it is proposed that Pluto's reorientation indicates the presence of a global ocean, our model indicates that it occurs even if no ocean.

The ALMA [CII] Resolved Ism in STar-forming gALaxies (CRISTAL) survey is a Cycle 8 ALMA Large Programme that studies the cold gas component of high-redshift galaxies. Its sub-arcsecond resolution observations are key to disentangling physical mechanisms that shape galaxies during cosmic dawn. In this paper, we explore the morphology and kinematics of the cold gas, star-forming, and stellar components in the star-forming main-sequence galaxy CRISTAL-05/HZ3, at z = 5.54. Our analysis includes 0.3" spatial resolution (~2 kpc) ALMA observations of the [CII] line. While CRISTAL-05 was previously classified as a single source, our observations reveal that the system is a close interacting pair surrounded by an extended component of carbon-enriched gas. This is imprinted in the disturbed elongated [CII] morphology and the separation of the two components in the position-velocity diagram (~100 km/s). The central region is composed of two components, named C05-NW and C05-SE, with the former being the dominant one. A significant fraction of the [CII] arises beyond the close pair up to 10 kpc, while the regions forming new massive stars and the stellar component seem compact (r_[CII] ~ 4 r_UV), as traced by rest-frame UV and optical imaging obtained with the Hubble Space Telescope and the James Webb Space Telescope. Our kinematic model, using the DYSMALpy software, yields a minor contribution of dark matter of C05-NW within a radius of ~2x Reff. Finally, we explore the resolved [CII]/FIR ratios as a proxy for shock-heating produced by this merger. We argue that the extended [CII] emission is mainly caused by the merger, which could not be discerned with lower-resolution observations. Our work emphasizes the need for high-resolution observations to fully characterize the dynamic stages of infant galaxies and the physical mechanisms that drive the metal enrichment of the circumgalactic medium.

Exoplanet habitability remains a challenging field due to the large distances separating Earth from other stars. Using insights from biology and astrophysics, we studied the habitability of M-dwarf exoplanets by modeling their surface temperature and flare UV and X-ray doses using the Martian atmosphere as a shielding model. Analyzing the Proxima Centauri and TRAPPIST-1 systems, our models suggest that Proxima b and TRAPPIST-1 e are likeliest to have temperatures compatible with surface liquid water, as well as tolerable radiation environments. Results of the modeling were used as a basis for microbiology experiments to assess spore survival of the melanin-rich fungus Aspergillus niger to exoplanet-like radiation (UV-C and X-rays). Results showed that A. niger spores can endure superflare events on M-dwarf planets when shielded by a Mars-like atmosphere or by a thin layer of soil or water. Melanin-deficient spores suspended in a melanin-rich solution showed higher survival rates and germination efficiency when compared to melanin-free solutions. Overall, the models developed in this work establish a framework for microbiological research in habitability studies. Finally, we showed that A. niger spores can survive harsh radiation conditions of simulated exoplanets, also emphasizing the importance of multifunctional molecules like melanins in radiation shielding beyond Earth.

Exoplanet discovery at long orbital periods requires reliably detecting individual transits without additional information about the system. Techniques like phase-folding of light curves and periodogram analysis of radial velocity data are more sensitive to planets with shorter orbital periods, leaving a dearth of planet discoveries at long periods. We present a novel technique using an ensemble of Convolutional Neural Networks incorporating the onboard spacecraft diagnostics of \emph{Kepler} to classify transits within a light curve. We create a pipeline to recover the location of individual transits, and the period of the orbiting planet, which maintains $>80\%$ transit recovery sensitivity out to an 800-day orbital period. Our neural network pipeline has the potential to discover additional planets in the \emph{Kepler} dataset, and crucially, within the $\eta$-Earth regime. We report our first candidate from this pipeline, KOI 1271.02. KOI 1271.01 is known to exhibit strong Transit Timing Variations (TTVs), and so we jointly model the TTVs and transits of both transiting planets to constrain the orbital configuration and planetary parameters and conclude with a series of potential parameters for KOI 1271.02, as there is not enough data currently to uniquely constrain the system. We conclude that KOI 1271.02 has a radius of 5.32 $\pm$ 0.20 $R_{\oplus}$ and a mass of $28.94^{0.23}_{-0.47}$ $M_{\oplus}$. Future constraints on the nature of KOI 1271.02 require measuring additional TTVs of KOI 1271.01 or observing a second transit of KOI 1271.02.

An unbiased spectral survey of V883 Ori, an eruptive young star, was carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 6. The detected line emission from various molecules reveals morphological/kinematical features in both the Keplerian disk and the infalling envelope. A direct infall signature, red-shifted absorption against continuum, has been detected in CO, HCO$^+$, HCN, HNC, and H$_2$CO. HCO$^+$ and SO show large arm-like structures that probably connect from an infalling envelope to the disk. HCN and H$_2$CO reveal a distinct boundary between the inner and outer disk and reveal tentative spiral structures connecting the outer disk to the inner disk. HNC shows a large central emission hole (r $\sim$0.3\arcsec) due to its chemical conversion to HCN at high temperatures. The HDO emission, a direct tracer of the water sublimation region, has been detected in the disk. Molecular emission from complex organic molecules (COMs) is confined within the HDO emission boundary, and HCO$^+$ has an emission hole in its distribution due to its destruction by water. Together, these features suggest that the current episode of eruption in V883 Ori may be triggered by the infall from the envelope to the outer disk, generating a spiral wave, which propagates inward and greatly enhances the accretion onto the central star.

We have comprehensively studied the multi-scale physical properties of the infrared dark cloud (IRDC) G28.34 (the Dragon cloud) with dust polarization and molecular line data from Planck, FCRAO-14m, JCMT, and ALMA. We find that the averaged magnetic fields of clumps tend to be either parallel with or perpendicular to the cloud-scale magnetic fields, while the cores in clump MM4 tend to have magnetic fields aligned with the clump fields. Implementing the relative orientation analysis (for magnetic fields, column density gradients, and local gravity), Velocity Gradient Technique, and modified Davis-Chandrasekhar-Fermi analysis, we find that: G28.34 is located in a trans-to-sub-Alfv\'{e}nic environment ($\mathcal{M}_{A}=0.74$ within $r=15$ pc); the magnetic field is effectively resisting gravitational collapse in large-scale diffuse gas, but is distorted by gravity within the cloud and affected by star formation activities in high-density regions; and the normalized mass-to-flux ratio tends to increase with density and decrease with radius. Considering both the magnetic and turbulent support, we find that the environmental gas of G28.34 is in a super-virial (supported) state, the infrared dark clumps may be in a near-equilibrium state, and core MM4-core4 is in a sub-virial (gravity-dominant) state. In summary, we suggest that magnetic fields dominate gravity and turbulence in the cloud environment at large scales, resulting in relatively slow cloud formation and evolution processes. Within the cloud, gravity could overwhelm both magnetic fields and turbulence, allowing local dynamical star formation to happen.

The values of Hubble constant H0 by direct measurements with standard distance ladder are typically larger than those obtained from the observation of cosmic microwave background and the galaxy survey with inverse distance ladder. On the other hand, although the errors are still large, various determinations of the value of matter density parameter Omega_m are consistent with each other. Therefore, it is possible that the difference in Hubble constant is translated to the difference of physical matter energy density omega_m = Omega_m h^2, where h = H0 / (100 Km/s/Mpc). In this article it is examined the possibility of an increase of the physical dark matter energy density by a fast transition at a certain value of redshift as a possible resolution of the Hubble tension. A phenomenological fluid model of the dark sector, which is the modification of a so-called unified dark matter model, is introduced to concretely realize such a fast transition in the physical dark matter energy density.

Weak Lensing (WL) surveys are reaching unprecedented depths, enabling the investigation of very small angular scales. At these scales, nonlinear gravitational effects lead to higher-order correlations making the matter distribution highly non-Gaussian. Extracting this information using traditional statistics has proven difficult, and Machine Learning based summary statistics have emerged as a powerful alternative. We explore the capabilities of a discriminative, Convolutional Neural Networks (CNN) based approach, focusing on parameter constraints in the ($\Omega_m$, $\sigma_8$) cosmological parameter space. Leveraging novel training loss functions and network representations on WL mock datasets without baryons, we show that our models achieve $\sim 5$ times stronger constraints than the power spectrum, $\sim 3$ stronger constraints than peak counts, and $\sim 2$ stronger constraints than previous CNN-learned summary statistics and scattering transforms, for noise levels relevant to Rubin or Euclid. For WL convergence maps with baryonic physics, our models achieve $\sim 2.3$ times stronger constraining power than the power spectrum at these noise levels, also outperforming previous summary statistics. To further explore the possibilities of CNNs for this task, we also discuss transfer learning where we adapt pre-trained models, trained on different tasks or datasets, for cosmological inference, finding that these do not improve the performance.

The debate regarding the emission mechanism in gamma-ray bursts has been long-standing. Here, we study the spectral signatures of photospheric emission, accounting for subphotospheric dissipation by a radiation-mediated shock. The shocks are modeled using the Kompaneets RMS approximation (KRA). We find that the resulting observed spectra are soft, broad, and exhibit an additional break at lower energies. When fitting a collection of 150 mock data samples generated by the model, we obtain a distribution of the low-energy index $\alpha$ that is similar to the observed one. These results are promising and show that dissipative photospheric models can account for many of the observed properties of prompt gamma-ray burst emission.

The orbital dynamics of a very young asteroid pair (5026) Martes and 2005 WW113 is studied. We detect strong resonant perturbations of the larger member of the pair (5026) Martes by the 3:11 mean motion resonance with the Earth. The second asteroid of the pair (2005 WW113) has orbited far from the resonance and is not perturbed. We provide a new estimation of the resonance structure and found that, under the planetary perturbations, a single resonance splits into a multiplet. The nominal position of the resonance is 2.37783 AU. However, the center of the corresponding chaotic zone is detected at 2.37754 AU. As a result, we noted a small but not negligible difference between the calculated and observed position of resonance. The multiplet structure of the 3:11 Earth resonance cannot explain this offset (the position of the main term of the multiplet is 2.377698 AU).

By general relativistic magnetohydrodynamic simulations, it is suggested that the rotational energy of a rapidly rotating black hole (BH) is preferentially extracted along the magnetic field lines threading the event horizon in the middle and lower latitudes. Applying this angle-dependent Poynting flux to the jet downstream, we demonstrate that the jets exhibit limb-brightened structures at various viewing angles, as observed from Mrk 501, M87, and Cyg A between 5 and 75 degrees, and that the limb-brightening is enhanced when the jet is collimated strongly. It is also found that the jet width perpendicular to the propagation direction shrinks at the projected distance of the altitude where the jet collimates from a conical shape (near the BH) to a parabolic one (in the jet). Comparing with the VLBI observations, we show this collimation takes place within the de-projected altitude of 100 Schwarzschild radii from the BH in the case of the M87 jet.

Context. We propose that the X-ray filaments emerging from selected bow shock pulsar wind nebulae are due to a charge-separated outflow of electrons and/or positrons escaping the nebula and propagating along the local Galactic magnetic field. Aims. The X-ray brightness, length, and thickness of filaments are all accounted for if a nonresonant streaming instability is excited. Methods. This is possible if particles are released in the interstellar medium as a collimated beam, as would be expected in a reconnection region between the nebular and interstellar magnetic fields. Results. We successfully test this idea on the Guitar Nebula filament and discuss other cases. Conclusions. These filaments provide the best diagnostics available for particle escape from evolved pulsar wind nebulae, a process essential to assessing the contribution of these sources to cosmic ray positrons. The same phenomenology might govern the occurrence of TeV halos and their importance for cosmic ray transport.

Using the MESA code, we have carried out a detailed survey of the available parameter space for the double-peaked type I X-ray bursts. We find that the double-peaked structure appears at mass accretion rate $\dot{M}$ in the range of $\sim(4-8)\times10^{-10}\,M_{\odot}/{\rm yr}$ when metallicity $Z=0.01$, while in the range of $\sim(4-8)\times10^{-9}\,M_{\odot}/\rm{yr}$ when $Z=0.05$. Calculations of the metallicity impact suggest that the double peaks will disappear when $Z\lesssim0.005$ for $\dot{M}=5\times10^{-10}\,M_{\odot}/\rm{yr}$ and $Z\lesssim0.04$ for $\dot{M}=5\times10^{-9}\,M_{\odot}/\rm{yr}$. Besides, the impacts of base heating $Q_{\rm b}$, as well as nuclear reaction waiting points: $^{22}\rm{Mg}$, $^{26}\rm{Si}$, $^{30}\rm{S}$, $^{34}\rm{Ar}$, $^{56}{\rm Ni}$, $^{60}\rm Zn$, $^{64}\rm{Ge}$, $^{68}\rm{Se}$, $^{72}\rm{Kr}$ have been explored. The luminosity of the two peaks decreases as $Q_{\rm b}$ increases. $^{68}{\rm Se}(p,\gamma){^{69}{\rm Br}}$ is the most sensitive reaction, the double peaks disappear assuming that $^{56}{\rm Ni}(p,\gamma)^{57}{\rm Cu}$ and $^{64}{\rm Ge}(p,\gamma)^{65}{\rm As}$ reaction rates have been underestimated by a factor of 100 and the $^{22}{\rm Mg}(\alpha,p)^{25}{\rm Al}$ reaction rate has been overestimated by a factor of 100, which indicates that $^{22}{\rm Mg}$, $^{56}{\rm Ni}$, $^{64}{\rm Ge}$, $^{68}{\rm Se}$ are possibly the most important nuclear waiting points impedance. Comparisons to the double-peaked bursts from 4U 1636-53 and 4U 1730-22 suggest that the nuclear origins of double-peaked type I X-ray bursts are difficult to explain the observed larger peak times ($t_{\rm p,1}\gtrsim4\,{\rm s}$, $t_{\rm p,2}\gtrsim8\,{\rm s}$) and smaller peak ratio($r_{1,2}\lesssim0.5$). The composition of ashes from double-peaked bursts is very different from the single-peaked bursts especially for the heavier p-nuclei.

Detecting planets within protoplanetary disks around young stars is essential for understanding planet formation and evolution. However, planet detection using the radial velocity method faces challenges due to strong stellar activity in these early stages. We aim to detect long-term periodicities in photometric and spectroscopic time series of the classical T Tauri star (CTTS) CI Tau, and retrieve evidence for inner embedded planets in its disk. The study conducted photometric and spectroscopic analyses using K2 and Las Cumbres Observatory Global Network light curves, and high-resolution spectra from ESPaDOnS and SPIRou. We focus our radial velocity analysis on a wavelength domain less affected by spot activity. To account for spot effects, a quasi-periodic Gaussian process model was applied to K2 light curve, ESPaDOnS, and SPIRou radial velocity data. Additionally, a detailed bisector analysis on cross-correlation functions was carried out to understand the cause of long-term periodicity. We detect coherent periods at $\sim$ 6.6 d, 9 d, $\sim$ 11.5 d, $\sim$ 14.2 d and $\sim$ 25.2 d, the latter is seen consistently across all datasets. Bisector analysis of the cross-correlation functions provides strong hints for combined activity-induced and Doppler reflex signal in the radial velocities at a period of 25.2 d. Our analysis suggests that this periodicity is best explained by the presence of a 3.6$\pm$0.3 M$_{Jup}$, eccentric (e$\sim$0.58) planet at a semi-major axis of 0.17 au. Our study outlines the difficulty of searching for disk-embedded planets in the inner 0.1 au's of young and active systems. We demonstrate that, when searching for planets in actively accreting stars such as CI Tau, the primary limitation is stellar activity rather than the precision of RV measurements provided by the instrument.

We present a suite of high-resolution numerical simulations to study the evolution and survival of dust in hot galactic winds. We implement a novel dust framework in the Cholla hydrodynamics code and use wind tunnel simulations of cool, dusty clouds to understand how thermal sputtering affects the dust content of galactic winds. Our simulations illustrate how various regimes of cloud evolution impact dust survival, dependent on cloud size, wind properties, and dust grain size. We find that significant amounts of dust can survive in winds in all scenarios, even without shielding from the cool phase of outflows. We present an analytic framework that explains this result, along with an analysis of the impact of cloud evolution on the total fraction of dust survival. Using these results, we estimate that 60 percent of dust that enters a starburst-driven wind could survive to populate the halo, based on a simulated distribution of cloud properties. We also investigate how these conclusions depend on grain size, exploring grains from 0.1 micron to 10 Angstrom. Under most circumstances, grains smaller than 0.01 micron cannot withstand hot-phase exposure, suggesting that the small grains observed in the CGM are either formed in situ due to shattering of larger grains, or must be carried there in cool phase outflows. Finally, we show that the dust-to-gas ratio of clouds declines as a function of distance from the galaxy due to cloud-wind mixing and condensation. These results provide an explanation for the vast amounts of dust observed in the CGMs of galaxies and beyond.

We develop a tool for the analysis of stochastic gravitational wave backgrounds from cosmological first-order phase transitions with LISA: we initiate a template databank for these signals, prototype their searches, and forecast their reconstruction. The templates encompass the gravitational wave signals sourced by bubble collisions, sound waves and turbulence. Accounting for Galactic and extra-Galactic foregrounds, we forecast the region of the parameter space that LISA will reconstruct with better than $\sim 10\,\%$ accuracy, if certain experimental and theoretical uncertainties are solved by the time LISA flies. We illustrate the accuracy with which LISA can reconstruct the parameters on a few benchmark signals, both in terms of the template parameters and the phase transition ones. To show the impact of the forecasts on physics beyond the Standard Model, we map the reconstructed benchmark measurements into the parameter spaces of the singlet extension of the Standard Model and of the classically conformal invariant $U(1)_{B-L}$ model.

Context. The recent discovery of several ultra high-energy gamma-ray emitters in our Galaxy constitutes a significant advancement towards unveiling its most powerful accelerators and their properties. Nonetheless, in order to unambiguously locate the regions where the highest energy particles are produced and understand the responsible physical mechanisms, detailed spectral and morphological studies are required, especially given that most of the observed sources were found to be significantly extended. Aims. In these regards, pointing observations with the next-generation Imaging Atmospheric Cherenkov Telescopes, like the Cherenkov Telescope Array (CTA) Observatory and the ASTRI Mini-Array (ASTRI), are expected to provide significant improvements. Here we aim at identifying the most promising sources to target in future observations. Methods. To this purpose, we performed a comparative analysis of the expected performance of ASTRI and CTA, computing their differential sensitivities towards extended sources, and further explored their capabilities with respect to specific case studies, including follow-ups of existing gamma-ray source catalogs. Results. We find that almost all of the sources so far detected by LHAASO-WCDA and HGPS will be in the reach of ASTRI and CTA with 300 and 50 hours of exposure, respectively. For the highest energy emitters detected by LHAASO-KM2A, in turn, we provide the list of the most promising objects to be investigated. We further examined specific classes of sources in order to identify potentially detectable gamma-ray emitters, such as passive molecular clouds (i.e. illuminated by the cosmic-ray sea) and pulsars surrounded by a halo of runaway particles.

We present here an extended nuclear network, with 90 species, designed for being coupled with hydrodynamic simulations, which includes neutrons, protons, electrons, positrons, and the corresponding neutrino and anti-neutrino emission. This network is also coupled with temperature, making it extremely robust and, together with its size, unique of its kind. The inclusion of electron captures on free protons makes the network very appropriate for multidimensional studies of Type Ia supernova explosions, especially when the exploding object is a massive white dwarf. The results obtained with the proposed medium-sized network compare fairly well, to a few percent, with those computed with the extended network WinNet (> 2000 isotopes) in scenarios reproducing the gross physical conditions of current Type Ia supernova explosion models. In those cases where the carbon and oxygen fuel ignites at high density, the high-temperature plateau typical of the nuclear statistical equilibrium regime is well defined and stable, allowing large integration time steps. We show that the inclusion of electron captures on free protons substantially improves the estimation of the electron fraction of the mixture. Therefore, the pressure is better determined than in networks where electron captures are excluded, which will ultimately lead to more reliable hydrodynamic models. Explosive combustion of helium at low density, occurring near the surface layer of a white dwarf, is also better described with the proposed network, which gives nuclear energy generation rates much closer to WinNet than typical reduced alpha networks.

The hydrogen deuteride (HD) molecule is an important deuterium tracer in astrophysical studies. The atmospheres of gas giants are dominated by molecular hydrogen, and simultaneous observation of H$_2$ and HD lines provides reliable information on the D/H ratios on these planets. The reference spectroscopic parameters play a crucial role in such studies. Under thermodynamic conditions encountered in these atmospheres, the spectroscopic studies of HD require not only the knowledge of line intensities and positions but also accurate reference data on pressure-induced line shapes and shifts. Our aim is to provide accurate collision-induced line-shape parameters for HD lines that cover any thermodynamic conditions relevant to the atmospheres of giant planets, i.e., any relevant temperature, pressure, and perturbing gas (the H$_2$/He mixture) composition. We perform quantum-scattering calculations on a new highly accurate ab initio potential energy surface, and we use scattering S-matrices obtained this way to determine the collision-induced line-shape parameters. We use the cavity ring-down spectroscopy for validation of our theoretical methodology. We report accurate collision-induced line-shape parameters for the pure rotational R(0), R(1), and R(2) lines, the most relevant HD lines for the investigations of atmospheres of the giant planets. Besides the basic Voigt-profile collisional parameters (i.e. the broadening and shift parameters), we also report their speed dependences and the complex Dicke parameter, which can influence the effective width and height of the HD lines up to almost a factor of 2 for giant planet conditions. The sub-percent-level accuracy, reached in this work, considerably improves the previously available data. All the reported parameters are consistent with the HITRAN database format, hence allowing for the use of HAPI for generating the beyond-Voigt spectra of HD.

In 2013, the IceCube collaboration announced the detection of a diffuse high-energy astrophysical neutrino flux. The origin of this flux is still largely unknown. The most significant individual source is the close-by Seyfert galaxy NGC 1068 at 4.2-sigma level with a soft spectral index. To identify sources based on their counterpart, IceCube releases realtime alerts corresponding to neutrinos with a high probability of astrophysical origin. We report here the spatial coincidence of two neutrino alerts, IC220424A and IC230416A, with the Seyfert galaxy NGC 7469 at a distance of 70 Mpc. We evaluate, a-posteriori, the chance probability of such a coincidence and discuss this source as a neutrino emitter based on its multi-wavelength properties and in comparison to NGC 1068. To calculate the chance coincidence considering neutrino emission from a specific source population, we perform a Goodness-of-Fit test with a test statistic derived from a likelihood ratio that includes the neutrino angular uncertainty and the source distance. We apply this test first to a catalog of AGN sources and second to a catalog of Seyfert galaxies only. Our a-posteriori evaluation excludes the chance coincidence of the two neutrinos with the Seyfert galaxy NGC 7469 at 3.3-sigma level. To be compatible with non-detections of TeV neutrinos, the source would need to have a hard spectral index.

Axion dark matter can form stable, self-gravitating, and coherent configurations known as axion stars, which are rendered unstable above a critical mass by the Chern-Simons coupling to electromagnetism. We study, using numerical relativity, the merger and subsequent decay of compact axion stars. We show that two sub-critical stars can merge, and form a more massive, excited and critical star, which survives for a finite period before rapidly decaying via electromagnetic radiation. We find a rich multimessenger signal, composed of gravitational waves, electromagnetic radiation, and axion radiation. The gravitational wave signal is broken into two parts: a weak and broad signal from the merger, followed by a much stronger signal of almost fixed frequency from the decay. The electromagnetic radiation follows only the gravitational waves from the decay, while the axion signal is continuous throughout the process. We briefly discuss the detectability of such a signal.

Brans-Dicke (BD) was one of the first proposed scalar-tensor theories of gravity, and effectively turns the gravitational constant of General Relativity (GR) time-dependent. Constraints on the BD parameter $\omega$ serve as a benchmark for testing GR, which is recovered in the limit $\omega \rightarrow \infty$. Current small-scale astrophysical constraints $\omega \gtrsim 10^5$ are much tighter than large-scale cosmological constraints $\omega \gtrsim 10^3$, but these decouple if the true theory of gravity features screening. On the largest cosmological scales BD approximates the most general second order scalar-tensor (Horndeski) theory, so constraints here have wider implications. These will improve with upcoming large-scale structure and CMB surveys. To constrain BD with weak gravitational lensing, one needs its non-linear matter power spectrum $P_{\rm BD}$. By comparing the boost $B = P_{\rm BD}/P_{\rm GR}$ from linear theory and non-linear $N$-body simulations, we show that the non-linear boost can simply be predicted from linear theory if the ${\rm BD}$ and ${\rm GR}$ universes are parametrized in a way that makes their early cosmological evolution and quasi-linear power today similar. In particular, they need the same $H_0 / \sqrt{\smash[b]{G_{\rm eff}(a=0)}}$ and $\sigma_8$, where $G_{\rm eff}$ are their (effective) gravitational strengths. Our prediction is $1\%$ accurate for $\omega \geq 100$, $z \leq 3$ and $k \leq 1\,h/\rm{Mpc}$, and $2\%$ further up to $k \leq 5\,h/\rm{Mpc}$. It also holds for $G_{\rm BD}$ that do not match Newton's constant today, so one can study GR with different gravitational constants $G_{\rm GR}$ by sending $\omega \rightarrow \infty$. We provide a code that computes $B$ with the linear Einstein-Boltzmann solver hi_class and multiplies it by the non-linear $P_{\rm GR}$ from EuclidEmulator2 to predict $P_{\rm BD}$.

With current and planned gravitational-wave (GW) observing runs, coincident multimessenger timing of Resonant Shattering Flares (RSFs) and GWs may soon allow for neutron star (NS) asteroseismology to be used to constrain the nuclear symmetry energy, an important property of fundamental nuclear physics that influences the composition and equation of state of NSs. In this work we examine the effects of combining multiple RSF detections on these symmetry energy constraints, and consider how realistic uncertainties in the masses of the progenitor NSs may weaken them. We show that the detection of subsequent multimessenger events has the potential to substantially improve constraints beyond those obtained from the first, and that this improvement is insensitive to the mass of the NSs which produce the RSFs and its uncertainty. This sets these asteroseismic constraints apart from bulk NS properties such as radius, for which the NS mass is highly important, meaning that any multimessenger RSF and GW events can equally improve our knowledge of fundamental physics.

When fitting cosmological models to data, a Bayesian framework is commonly used, requiring assumptions on the form of the likelihood and model prior. In light of current tensions between different data, it is interesting to investigate the robustness of cosmological measurements to statistical assumptions about the likelihood distribution from which the data was drawn. We consider the impact of changes to the likelihood caused by uncertainties due to the finite number of mock catalogs used to estimate the covariance matrix, leading to the replacement of the standard Gaussian likelihood with a multivariate $t$-distribution. These changes to the likelihood have a negligible impact on recent cosmic microwave background (CMB) lensing and baryon acoustic oscillation (BAO) measurements. We then extend our analysis to perform a sensitivity test on the Gaussian likelihoods typically adopted, considering how increasing the size of the tails of the likelihood (again using a $t$-distribution) affects cosmological inferences. For an open $\Lambda$CDM model constrained by BAO alone, we find that increasing the weight in the tails shifts and broadens the resulting posterior on the parameters, with a $\sim$0.2-0.4$\sigma$ effect on $\Omega_\Lambda$ and $\Omega_{\rm k}$. In contrast, the CMB temperature and polarization constraints in $\Lambda$CDM showed less than 0.03$\sigma$ changes in the parameters, except for $\{\tau$, ln($10^{10}A_{\rm s})$, $\sigma_8$, $S_8$, $\sigma_8\Omega_{\rm m}^{0.25}$, $z_{\rm re}$, $10^9A_{\rm s}e^{-2\tau}\}$ which shifted by around 0.1-0.2$\sigma$. If we use solely $\ell < 30$ data, the amplitude $A_{\rm s} e^{-2\tau}$ varies in the posterior mean by 0.7$\sigma$ and the error bars increase by 6%. We conclude, at least for current-generation CMB and BAO measurements, that uncertainties in the shape and tails of the likelihood do not contribute to current tensions.

Baryonic feedback is a major systematic in weak lensing cosmology. Its most studied effect is the suppression of the lensing power spectrum, a second-order statistic, on small scales. Motivated by the growing interest in statistics beyond the second order, we investigate the effect of baryons on lensing non-Gaussian statistics and the resulting biases in the matter clustering amplitude $S_8 = \sigma_8\sqrt{\Omega_m/0.3}$. We focus on the Subaru Hyper Suprime-Cam Year 1 (HSC-Y1) data which, with its high source number density, closely resembles those expected from the upcoming Euclid and Rubin LSST. We study four non-Gaussian statistics -- peak counts, minimum counts, the probability distribution function, and the scattering transform -- in addition to the usual power spectrum. We first estimate the biases in $S_8$ using mock observations built from the IllustrisTNG and BAHAMAS hydrodynamical simulations and theoretical models built from dark matter-only simulations. We find up to $1\sigma$ bias in $S_8$ when the smallest scales (2 arcmin) and the highest feedback level are considered. We then analyze the HSC-Y1 data and compare the $S_8$ obtained for each statistic with different smoothing scales or scale cuts. As we expect that baryons mostly affect the small scales, comparing the results obtained from including and excluding small scales can indicate the level of impact from baryons. With HSC data, we find only minor ($\leq0.5\sigma$) differences in $S_8$ for all statistics, even when considering very small scales (2 arcmin). Our results suggest that the effect of baryons is insignificant at the level of HSC-Y1 down to 2~arcmin for all statistics examined here, or it is canceled by other scale-dependent systematics.

We present the results of our observations using the Giant Meterwave Radio Telescope (GMRT) to investigate the radio continuum and OH line emission of 10 OHM candidates from the Arecibo Legacy Fast ALFA (ALFALFA) survey. Among these candidates, we have identified two sources, AGC115713 and AGC249507, which display compact OH line emission that are spatially associated with radio continuum emission. These characteristics align with the typical properties of OHM galaxies. Furthermore, the infrared (IR) properties of these two galaxies are consistent with those of known OHM galaxies. %Importantly, these two sources have been independently confirmed by alternative methods. Of the two sources, AGC 249507 has been confirmed through optical redshift, whereas AGC 115713 meets a WISE color selection criterion in the literature, providing additional support for this source being an OHM galaxy rather than a nearby \HI galaxy. On the contrary, no significant spectral line emission were detected in the remaining eight OHM candidates using our full GMRT dataset. This suggests that the spectral line emission initially detected by the ALFALFA survey may have been significantly resolved in our high-resolution observations. Additionally, the absence of radio continuum emission in 6 candidates also distinguishes them from known OHM galaxies documented in the literature. These findings support the notion that OHM emission may be distributed on a subarcsecond scale, underscoring the utility of arcsecond-scale observations in confirming OHM candidates, particularly those lacking optical redshift data.

We present the updated galaxy cluster catalog of the second Planck catalog of Sunyaev-Zeldovich sources (PSZ2) through the compilation of the data for clusters and galaxies with spectroscopically measured redshifts in the literature. The original version of PSZ2 comprises 1653 SZ sources, of which 1203 have been validated as genuine galaxy clusters, while the remaining 450 sources are yet to be validated. To increase the number of genuine clusters in PSZ2, we first update the validations of the cluster candidates and their redshift information using the data compiled for the confirmed clusters and the member galaxies in the literature. We then use the galaxy redshift data in the fields of the remaining cluster candidates, by searching for possible member galaxies with measured spectroscopic redshifts around the Sunyaev-Zeldovich centroids. In this search process, we classify clusters as strong candidates if they contain more than nine galaxies within a 4500 km s$^{-1}$ velocity range and within 15 arcmin around the Sunyaev-Zeldovich centroids. This process results in the validation of 139 new genuine clusters, the update of redshift information on 399 clusters, and the identification of 10 strong candidates, which increases the number of validated clusters up to 1334 among the 1653 SZ sources. Our updated galaxy cluster catalog will be very useful for the studies of galaxy formation and cosmology through the combination with other all-sky surveys including WISE and SPHEREx.

The EHT has captured a series of images of black holes, demonstrating the possibility of detecting them through a radio interferometer. These images could provide valuable information about the gravitational environment near the event horizon. However, accurate detection and parameter estimation for candidate black holes are necessary. This paper explores the potential for identifying black holes in the ultraviolet band using space telescopes. Firstly, a data pipeline is established for generating simulated observations. Next, we present an ensemble neural network model for detecting and estimating the parameters of black holes with different angular sizes. The model can achieve a mean average precision value [0, 0.5] of 0.9176 when reaching the imaging FWHM ($\theta_c$) of the telescope and maintains its detection ability until $0.33\theta_c$. These results indicate that our methodology enables super-resolution recognition. The model accurately estimates the size of the accretion disk, the inclination angle, the positional angle, and the temperature. This provides a specific scheme for automatically detecting captured images using neural networks. Moreover, the validity of the model is assessed by analyzing the shadow of M87*, which indicates that the model can discriminate the black hole from background noise and other celestial objects with a confidence level of 0.639. Our work demonstrates the feasibility of detecting black holes in the UV band and provides a new method for the accurate and real-time detection of candidate black holes and further parameter estimation.

During the final stage of planetary formation, different formation pathways of planetary embryos could significantly influence the observed variations in planetary densities. Of the approximately 5,000 exoplanets identified to date, a notable subset exhibit core fractions reminiscent of Mercury, potentially a consequence of high-velocity giant impacts. In order to better understand the influence of such collisions on planetary formation and compositional evolution, we conducted an extensive set of smoothed particle hydrodynamics giant impact simulations between two-layered rocky bodies. These simulations spanned a broad range of impact velocities from one to eleven times the mutual escape velocity. We derived novel scaling laws that estimate the mass and core mass fraction of the largest post-collision remnants. Our findings indicate that the extent of core vaporization markedly influences mantle stripping efficiency at low impact angles. We delineate the distinct roles played by two mechanisms -- kinetic momentum transfer and vaporization-induced ejection -- in mantle stripping. Our research suggests that collisional outcomes for multi-layered planets are more complex than those for undifferentiated planetesimal impacts. Thus, a single universal law may not encompass all collision processes. We found a significant decrease in the mantle stripping efficiency as the impact angle increases. To form a 5 M$_{\oplus}$ super-Mercury at $45^{\circ}$, an impact velocity over 200 km s$^{-1}$ is required. This poses a challenge to the formation of super-Mercuries through a single giant impact, implying that their formation would either favor relatively low-angle single impacts or multiple

We present a superfluid dark star model consisting of relativistic dark bosons with two-body self-interaction. The obtained masses, radii, and tidal deformability depend in a simple way on the boson mass and interaction strength. We report first results on binary mergers: the distinctive amplitude and frequency of the emitted gravitational waves are well within reach of terrestrial interferometers.

Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, $m$, is in the so-called 'asteroid-mass window', $10^{17} \, {\rm g} \lesssim m \lesssim 10^{22} \, {\rm g}$. Observational constraints on the abundance of PBHs are usually calculated assuming they all have the same mass, however this is unlikely to be a good approximation. PBHs formed from the collapse of large density perturbations during radiation domination are expected to have an extended mass function (MF), due to the effects of critical collapse. The PBH MF is often assumed to be lognormal, however it has recently been shown that other functions are a better fit to numerically calculated MFs. We recalculate both current and potential future constraints for these improved fitting functions. We find that for current constraints the asteroid-mass window narrows, but remains open (i.e. all of the DM can be in the form of PBHs) unless the PBH MF is wider than expected. Future evaporation and microlensing constraints may together exclude all of the DM being in PBHs, depending on the width of the PBH MF and also the shape of its low and high mass tails.

We calculate the one-loop corrections in bispectrum of CMB scale perturbations induced from the small scale modes undergoing an intermediate phase of USR inflation in scenarios employed for PBHs formation. Using the formalism of effective field theory of inflation we calculate the cubic and quartic Hamiltonians and perform the in-in analysis for a subset of Feynman diagrams comprising both the cubic and the quartic exchange vertices. We show the one-loop corrections in bispectrum has the local shape with $f_{NL}$ having the same structure as the one-loop correction in power spectrum in their dependence on the duration of the USR phase and the sharpness of the transition to the final attractor phase. It is shown that in the models with a sharp transition the induced loop corrections in bispectrum can quickly violate the observational bounds on $f_{NL}$.

Monoceros R2 (Mon R2) is one of the closest large active star-forming regions. This extremely young and partially embedded region provides an excellent laboratory for studying star formation and the early evolution of young stellar objects (YSOs). In this paper, we conduct an optical study of the greater Mon R2 region. Beginning with 1690 previously identified candidate YSOs, we used 496 sources with good proper motions and parallaxes from Gaia DR3 to determine the astrometric properties for likely members of Mon R2. We then used both astrometric and photometric (isochronal and variability) criteria to determine that 308 of these stars are highly probable members. Using the same criteria, we considered a broad area search around Mon R2 in Gaia DR3, and separated candidate members from field stars. In total, we selected 651 likely new cluster members that had been missed in the previous x-ray and infrared excess selection techniques used in the past to establish cluster membership. Revised astrometric properties of the cluster were found using the combined sample of ~959 highly probable member stars. For the literature plus new candidate member list, optical light curves were compiled from the Zwicky Transient Facility. For 470 identified variable sources, we attempted classification based on the Flux Asymmetry (M) and Quasi-Periodicity (Q) metrics. We find that Mon R2 is dominated by quasi-periodic symmetric variables, with aperiodic sources also a significant population. A few tens of large-amplitude variables are identified that may be of interest for further study.

The physical properties, evolution, and fragmentation of massive dense cores (MDCs, $\sim$ 0.1 pc) are fundamental pieces in our understanding of high-mass star formation. We aim to characterize the temperature, velocity dispersion, and fragmentation of the MDCs in the Cygnus X giant molecular cloud and to investigate the stability and dynamics of these cores. We present the Karl G. Jansky Very Large Array (VLA) observations of the NH$_3$ (J,K) = (1,1) and (2,2) inversion lines towards 35 MDCs in Cygnus X, from which we calculated the temperature and velocity dispersion. We extracted 202 fragments ($\sim$ 0.02 pc) from the NH$_3$ (1,1) moment-0 maps with the GAUSSCLUMPS algorithm. We analyzed the stability of the MDCs and their NH$_3$ fragments through evaluating the corresponding kinetic, gravitational potential, and magnetic energies and the virial parameters. The MDCs in Cygnus X have a typical mean kinetic temperature T$_K$ of $\sim$ 20 K. Our virial analysis shows that many MDCs are in subvirialized states, indicating that the kinetic energy is insufficient to support these MDCs against their gravity. The calculated nonthermal velocity dispersions of most MDCs are at transonic to mildly supersonic levels, and the bulk motions make only a minor contribution to the velocity dispersion. Regarding the NH$_3$ fragments, with T$_K$ $\sim$ 19 K, their nonthermal velocity dispersions are mostly trans-sonic to subsonic. Unless there is a strong magnetic field, most NH$_3$ fragments are probably not in virialized states. We also find that most of the NH$_3$ fragments are dynamically quiescent, while only a few are active due to star formation activity.

Magnification bias, an observational effect of gravitational lensing in the weak regime, allows testing the cosmological model through angular correlations of sources at different redshifts. This effect has been observed in various contexts, particularly with sub-millimeter galaxies (SMGs), offering astrophysical and cosmological insights. The study aims to investigate the magnification bias effect exerted by galaxy clusters on SMGs and its implications for astrophysical and cosmological parameters within the $\Lambda$CDM model. Magnification bias was explored through quantifying the cross-correlation function, utilised to derive constraints on cosmological and astrophysical parameters with a Markov Chain Monte Carlo algorithm. Two distinct galaxy cluster samples were used to assess result robustness and understand the influence of sample characteristics. Cluster samples show higher cross-correlation values than galaxies, with an excess at larger scales suggesting contributions from additional large-scale structures. The parameters obtained, while consistent with galaxies, are less constrained due to broader redshift distributions and limited cluster statistics. Results align with weak lensing studies, hinting at slightly lower $\sigma_8$ and $\Omega_m$ values than \emph{Planck}'s CMB data, emphasizing the need for enhanced precision and alternative low-redshift universe tests. While yielding constraints compatible with the $\Lambda$CDM model, limitations include broader redshift distributions and a limited number of lenses, resulting in less constrained parameters compared to previous galaxy studies. Nonetheless, the study underscores the potential of using galaxy clusters as lenses for magnification bias studies, capitalising on their elevated mass, providing a promising avenue to test current Cosmology theories. Further progress can be made by expanding the lens sample size.

In this work we have investigated the synergy between Stage-IV galaxy surveys and future GW observatories for constraining the underlying cosmological model of the Universe, focussing on photometric galaxy clustering, cosmic shear and GW magnification as cosmological probes. We have implemented a Fisher matrix approach for the evaluation of the full $6\times2$pt statistics composed by the angular power spectra of the single probes together with their combination. For our analysis, we have in particular considered dynamical dark energy and massive neutrino scenarios. We have found that the improvement to galaxy survey performance is below 1\%, in the case $\ell^{\rm GW}_{\rm max}=100$ and a luminosity distance error of $\sigma_{d_L}/d_L=10\%$. However, when extending the analysis to $\ell^{\rm GW}_{\rm max}=1000$, we find that the GW magnification improves the galaxy survey performance on all the cosmological parameters, reducing their errors by $3\%$-$5\%$, when $\sigma_{d_L}/d_L=10\%$, and by $10\%$-$18\%$ when $\sigma_{d_L}/d_L=1\%$, especially for $M_\nu$, $w_0$ and $w_a$. However, here our analysis is unavoidably optimistic: a much more detailed and realistic approach will be needed, especially by including systematic effects. But we can conclude that, in the case of future gravitational wave observatories the inclusion of the gravitational wave magnification can improve Stage-IV galaxy surveys performance on constraining the underlying cosmological model of the Universe.

Recent observations have found a large number of supermassive black holes already in place in the first few hundred million years after Big Bang. The channels of formation and growth of these early, massive black holes are not clear, with scenarios ranging from heavy seeds to light seeds experiencing bursts of high accretion rate. Here we present the detection, from the JADES survey, of broad Halpha emission in a galaxy at z=6.68, which traces a black hole with mass of ~ 4 * 10^8 Msun and accreting at a rate of only 0.02 times the Eddington limit. The host galaxy has low star formation rate (~ 1 Msun/yr, a factor of 3 below the star forming main sequence). The black hole to stellar mass ratio is ~ 0.4, i.e. about 1,000 times above the local relation, while the system is closer to the local relations in terms of dynamical mass and velocity dispersion of the host galaxy. This object is most likely the tip of the iceberg of a much larger population of dormant black holes around the epoch of reionisation. Its properties are consistent with scenarios in which short bursts of super-Eddington accretion have resulted in black hole overgrowth and massive gas expulsion from the accretion disk; in between bursts, black holes spend most of their life in a dormant state.

We utilize deep JWST NIRCam observations for the first direct constraints on the Galaxy Stellar Mass Function (GSMF) at z>10. Our EPOCHS v1 sample includes 1120 galaxy candidates at 6.5<z<13.5 taken from a consistent reduction and analysis of publicly available deep JWST NIRCam data covering the PEARLS, CEERS, GLASS, JADES GOOD-S, NGDEEP, and SMACS0723 surveys, totalling 187 arcmin2. We investigate the impact of SED fitting methods, assumed star formation histories (SFH), dust laws, and priors on galaxy masses and the resultant GSMF. Whilst our fiducial GSMF agrees with the literature at z<13.5, we find that the assumed SFH model has a large impact on the GSMF and stellar mass density (SMD), finding a 0.75 dex increase in the SMD at z=10.5 between a flexible non-parametric and standard parametric SFH. Overall, we find a flatter SMD evolution at z > 9 than some studies predict, suggesting a rapid buildup of stellar mass in the early Universe. We find no incompatibility between our results and those of standard cosmological models, as suggested previously, although the most massive galaxies may require a high star formation efficiency. We find that the 'Little Red Dot' galaxies dominate the z=7 GSMF at high-masses, necessitating a better understanding of the relative contributions of AGN and stellar emission. We show that assuming a theoretically motivated top-heavy IMF reduces stellar mass by 0.5 dex without affecting fit quality, but our results remain consistent with existing cosmological models with a standard IMF.

This contribution presents the recent research developments within the Cosmic Ray Extremely Distributed Observatory (CREDO) in the search for resolution of various scientific puzzles, ranging from fundamental physical questions to applications like the determination of earthquake precursors. The state-of-the art theoretical, numerical and computational aspects of these phenomena are addressed, as well as recent experimental developments for detection.

Quantifying disequilibria is important to understand whether an environment could be habitable. It has been proposed that the exoplanet K2-18b has a hydrogen-rich atmosphere and a water ocean, making it a "hycean world". The James Webb Space Telescope recently made measurements of methane, CO$_2$, and possibly dimethyl sulfide (DMS) in the atmosphere of this planet. The initial interpretation of these data is that they may support the occurrence of hycean conditions. Here, I attempt to take a next step in exploring the prospects for habitability. I use constraints on the abundances of atmospheric gases to calculate how much chemical disequilibrium there could be, assuming K2-18b is a hycean world. I find that the presence of oxidized carbon species coexisting with abundant H$_2$ (1-1000 bar) at cool to warm (25-120{\deg}C) conditions creates a strong thermodynamic drive for methanogenesis. More than ~75 kJ (mol C)$^{-1}$ of free energy can be released from CO$_2$ hydrogenation. Partially oxidized carbon compounds such as DMS (if present) also have potential to provide metabolic energy, albeit in smaller quantities. Because of the thermodynamic instability of CO$_2$ under hycean conditions, other reductive reactions of CO$_2$ are likely to be favored, including the synthesis of amino acids. Glycine and alanine synthesis can be energy-releasing or at least much less costly on K2-18b than in Earth's ocean, even when NH$_3$ is scarce but not totally absent. These first bioenergetic calculations for a proposed ocean-bearing exoplanet lay new groundwork for assessing exoplanetary habitability.

Stochastic gravitational waves (GWs) consist of a primordial component from early Universe processes and an astrophysical component from compact binary mergers. To detect the primordial stochastic GW background (SGWB), the astrophysical foregrounds must be reduced to high precision, which is achievable for third-generation (3G) ground based GW detectors. Previous studies have shown that the foreground from individually detectable merger events can be reduced with fractional residual energy density below $10^{-3}$, and the residual foreground from subthreshold binary neutron stars (BNSs) will be the bottleneck if not be well cleaned. In this work, we propose that the foreground energy density of subthreshold BNSs $\Omega_{\rm sub}$ can be estimated via a population based approach from the individually detectable BNSs utilizing the isotropic orbital orientations of all BNSs, i.e., uniform distribution in $\cos\iota$, where $\iota$ is the BNS inclination angle with respect to the line of sight. Using this approach, we find $\Omega_{\rm sub}$ can be measured with percent-level uncertainty, assuming $O(10^5)$ individually detected BNSs in our simulations. As a result, the sensitivity to the primordial SGWB will be limited by the detector noise and the total observation time, instead of the astrophysical foregrounds from compact binaries.

Different dark matter (DM) candidates could have different types of DM-lepton and/or DM-quark interactions. For direct detection experiments, this leads to diversity in the recoil spectra, where both DM-electron and DM-nucleus scatterings may contribute. Furthermore, kinematic effects such as those of the inelastic scattering can also play an important role in shaping the recoil spectra. In this work, we systematically study signatures of the light exothermic inelastic DM from the recoil spectra including both the DM-electron scattering and Migdal effect. Such inelastic DM has mass around (sub-)GeV scale and the DM mass-splitting ranges from 1keV to 30keV. We analyze the direct detection sensitivities to such light inelastic DM. For different inelastic DM masses and mass-splittings, we find that the DM-electron recoil and Migdal effect can contribute significantly and differently to the direct detection signatures. Hence, it is important to perform combined analysis to include both the DM-electron recoil and Migdal effect. We further demonstrate that this analysis has strong impacts on the cosmological and laboratory bounds for the inelastic DM.

We study nonthermal production of heavy dark matter from the dynamics of the background scalar field during a first-order phase transition, predominantly from bubble collisions. In scenarios where bubble walls achieve runaway behavior and get boosted to very high energies, we find that it is possible to produce dark matter with mass several orders of magnitude above the symmetry breaking scale or the highest temperature ever reached by the thermal plasma. We also demonstrate that the existing formalism for calculating particle production from bubble dynamics in a first-order phase transition is not gauge invariant, and can lead to spurious results. While a rigorous and complete resolution of this problem is still lacking, we provide a practical prescription for the computation that avoids unphysical contributions and should provide reliable order-of-magnitude estimates of this effect. Furthermore, we point out the importance of three-body decays of the background field excitations into scalars and gauge bosons, which provide the dominant contributions at energy scales above the scale of symmetry breaking. Using our improved results, we find that scalar, fermion, and vector dark matter are all viable across a large range of mass scales, from O(10) TeV to a few orders of magnitude below the Planck scale, and the corresponding phase transitions can be probed with current and future gravitational wave experiments.

Accurately modeling the tidal response of neutron stars is crucial to connecting gravitational wave observations of binaries to ultra-dense nuclear physics. Most current models of the tidal response of relativistic stars either assume a static response model, or use phenomenological models inspired by Newtonian gravity. In this work, we present a general formalism for computing the linear dynamical tidal response function of relativistic, spherically symmetric stars. Our formalism incorporates stratification due to thermal and chemical imbalances, allowing one to study the effects of g modes on the tidal response function. We also describe how to incorporate sources of dissipation due to shear and bulk viscosity. To showcase the utility of our approach, we present several applications for polytropic stars in general relativity. We show how our formalism can capture the dynamical tidal resonance due to the f and g modes of inviscid stars and explore the sensitivity of the dynamical tidal response to the compactness of the star. We also compute the dissipative tidal deformability due to bulk and shear viscous dissipation. We find that, for the same viscous profile, the shear viscous tidal lag parameter is 100-1000 times larger than the dimensionless bulk viscous tidal lag parameter.

We developed machine learning algorithms for distinguishing scintillation signals from a plastic-liquid coupled detector known as a phoswich. The challenge lies in discriminating signals from organic scintillators with similar shapes and short decay times. Using a single-readout phoswich detector, we successfully identified $\gamma$ radiation signals from two scintillating components. Our Boosted Decision Tree algorithm demonstrated a maximum discrimination power of 3.02 $\pm$ 0.85 standard deviation in the 950 keV region, providing an efficient solution for self-shielding and enhancing radiation detection capabilities.

The secondary component of GW190814 has mass in the range $2.5$--$2.67{\rm M}_\odot$, placing it within the lower mass gap separating neutron stars from black holes. According to the predictions of general relativity and state-of-the-art nuclear equations of state, this object is too heavy to be a neutron star.~In this work, we explore the possibility that this object is a neutron star under the hypothesis that general relativity is modified to include screening mechanisms, and that the neutron star formed in an unscreened environment. We introduce a set of parameterized-post-Tolman-Oppenheimer-Volkoff (post-TOV) equations appropriate for screened modified gravity whose free parameters are environment-dependent. We find that it is possible that the GW190814 secondary could be a neutron star that formed in an unscreened environment for a range of reasonable post-TOV parameters.

Two-level systems (TLS) are an important, if not dominant, source of loss and noise for superconducting resonators such as those used in kinetic inductance detectors and some quantum information science platforms. They are similarly important for loss in photolithographically fabricated superconducting mm-wave/THz transmission lines. For both lumped-element and transmission-line structures, native amorphous surface oxide films are typically the sites of such TLS in non-microstripline geometries, while loss in the (usually amorphous) dielectric film itself usually dominates in microstriplines. We report here on the demonstration of low TLS loss at GHz frequencies in hydrogenated amorphous silicon (a-Si:H) films deposited by plasma-enhanced chemical vapor deposition in superconducting lumped-element resonators using parallel-plate capacitors (PPCs). The values we obtain from two recipes in different deposition machines, 7$\,\times\,10^{-6}$ and 12$\,\times\,10^{-6}$, improve on the best achieved in the literature by a factor of 2--4 for a-Si:H and are comparable to recent measurements of amorphous germanium. Moreover, we have taken care to extract the true zero-temperature, low-field loss tangent of these films, accounting for temperature and field saturation effects that can yield misleading results. Such robustly fabricated and characterized films render the use of PPCs with deposited amorphous films a viable architecture for superconducting resonators, and they also promise extremely low loss and high quality factor for photolithographically fabricated superconducting mm-wave/THz transmission lines used in planar antennas and resonant filters.

This article advances the hypothesis that the heightened eschatological sensitivity evident among the historians writing in the 5th century and its weaker echos in the time of Charlemagne were caused by the irregularities of the the lunisolar calendar and its particular realization, the Easter calendar. The lunisolar calendar that Christians used for the calculation of the date of the Easter had a number of key periods when the cycles of the Sun and the Moon came in sync in relationship to the beginning of the count and thus produced an effect of the times repeating themselves or ending with the nearly precise astronomical repetition. It is shown that Late Antique scholars who were actively involved in the construction of the Christian history's chronology were limited in their choices by the astronomical peculiarities of the Earth-Moon system. The total conjunctions of the astronomical Solar and Lunar calendars took place, some within the 1st century CE, and the next one, in 483 CE. This was also a special year because the lunar calendar lost one day. Thus the 5th century was the time of heightened expectations of whether the calendar and the Moon's showings will repeat those that accompanied the birth of Jesus. The Full Supermoon (or whatever phase it was on December 25th, 1 BCE) may have repeated in 410 CE (the entry of Goths into Rome), in 467 CE and in 476 CE (the Fall of the Roman Empire), marking the coming of the time very similar to Jesus' birth. The Full Moon was supposed to repeat December 25th, 800 CE and in the year 1000 CE. This may have determined the setting of the biblical calendar in a way that put the birth of Christ on 5199 CE (making the year 800 CE, the year of the Full Supermoon or of its phase on December 25th, 1 BCE) a critical turning point.

The observation of gravitational waves from binary neutron star mergers offers insights into properties of extreme nuclear matter. However, their high-frequency signals in the kHz range are often masked by quantum noise of the laser light used. Here, we propose the "quantum expander with coherent feedback", a new detector design that features an additional optical cavity in the detector output and an internal squeeze operation. This approach allows to boost the sensitivity at high frequencies, at the same time providing a compact and tunable design for signal extraction. It allows to tailor the sensitivity of the detector to the specific signal frequency range. We demonstrate that our design allows to improve the sensitivity of the high-frequency detector concept NEMO (neutron star extreme matter observatory), increasing the detection rates by around 15%. Our approach promises new level of flexibility in designing the detectors aiming at high-frequency signals.

Different computational techniques for cosmological phase transition parameters can impact the Gravitational Wave (GW) spectra predicted in a given particle physics model. To scrutinize the importance of this effect, we perform large-scale parameter scans of the dynamical real-singlet extended Standard Model using three perturbative approximations for the effective potential: the $\overline{\rm MS}$ and on-shell schemes at leading order, and three-dimensional thermal effective theory (3D EFT) at next-to-leading order. While predictions of GW amplitudes are typically unreliable in the absence of higher-order corrections, we show that the reconstructed model parameter spaces are robust up to a few percent in uncertainty. While 3D EFT is accurate from one loop order, theoretical uncertainties of reconstructed model parameters, using four-dimensional standard techniques, remain dominant over the experimental ones even for signals merely strong enough to claim a detection by LISA.