Papers for Friday, Nov 22 2024

We present a detailed study of the large-scale shock front in Stephan's Quintet, a byproduct of past and ongoing interactions. Using integral-field spectroscopy from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), recent 144 MHz observations from the LOFAR Two-metre Sky Survey (LoTSS), and archival data from the Very Large Array and James Webb Space Telescope (JWST), we obtain new measurements of key shock properties and determine its impact on the system. Harnessing the WEAVE large integral field unit's (LIFU) field of view (90 $\times$ 78 arcsec$^{2}$), spectral resolution ($R\sim2500$) and continuous wavelength coverage across the optical band, we perform robust emission line modeling and dynamically locate the shock within the multi-phase intergalactic medium (IGM) with higher precision than previously possible. The shocking of the cold gas phase is hypersonic, and comparisons with shock models show that it can readily account for the observed emission line ratios. In contrast, we demonstrate that the shock is relatively weak in the hot plasma visible in X-rays (with Mach number of $\mathcal{M} \sim 2 - 4$), making it inefficient at producing the relativistic particles needed to explain the observed synchrotron emission. Instead, we propose that it has led to an adiabatic compression of the medium, which has increased the radio luminosity ten-fold. Comparison of the Balmer line-derived extinction map with the molecular gas and hot dust observed with JWST suggests that pre-existing dust may have survived the collision, allowing the condensation of H$_{2}$ - a key channel for dissipating the shock energy.

In light of recent observations, we study evidence for thawing quintessence over a cosmological constant as dark energy, with emphasis on the effect of the choice of priors. Working with a parametrization for the equation of state parameter motivated by the theory, we find a preference for thawing quintessence compared to a bare cosmological constant {\it only} if we use priors which are heavily informed by the data itself. If we extend the priors to physically better motivated ranges, the evidence for thawing quintessence disappears.

We report the discovery of five galaxy candidates at redshifts between $15.9<z<18.6$ in JWST observations from the GLIMPSE survey. These robust sources were identified using a combination of Lyman-break selection and photometric redshift estimates. The ultra-deep NIRCam imaging from GLIMPSE, combined with the strong gravitational lensing of the Abell S1063 galaxy cluster, allows us to probe an intrinsically fainter population (down to $M_{\rm UV}=-17.5$ mag) than previously achievable. These galaxies have absolute magnitudes ranging from $M_{\rm UV}= -17.7$ to $-18.0$ mag, with UV continuum slopes between $\beta \simeq -2.3$ and $\beta \simeq -3.0$, consistent with young, dust-free stellar populations. The number density of these objects, log$_{\rm 10}$ ($\phi$/[Mpc$^{-3}$ mag$^{-1}$])=$-3.43^{+0.28}_{-0.64}$ at $M_{\rm UV}=-18$ is in clear tension with pre-JWST theoretical predictions, extending the over-abundance of galaxies from $z\sim10$ to $z\sim 18.6$. These results, together with the scarcity of brighter galaxies in other public surveys, suggest a steep decline in the bright-end of the UV luminosity function at $z \sim 17$, implying efficient star formation and possibly a close connection to the halo mass function at these redshifts. Testing a variety of star formation histories suggests that these sources are plausible progenitors of the unusually UV-bright galaxies that JWST now routinely uncovers at $z = 10-14$. Overall, our results indicate that the luminosity distribution of the earliest star-forming galaxies could be shifting towards fainter luminosities, implying that future surveys of cosmic dawn will need to explore this faint luminosity regime.

As imaging surveys progress in exploring the large-scale structure of the Universe through the use of weak gravitational lensing, achieving subpercent accuracy in estimating shape distortions caused by lensing, or shear, is imperative for precision cosmology. In this paper, we extend the \texttt{FPFS} shear estimator using fourth-order shapelet moments and combine it with the original second-order shear estimator to reduce galaxy shape noise. We calibrate this novel shear estimator analytically to a subpercent level accuracy using the \texttt{AnaCal} framework. This higher-order shear estimator is tested with realistic image simulations, and after analytical correction for the detection/selection bias and noise bias, the multiplicative shear bias $|m|$ is below $3\times10^{-3}$ ($99.7\%$ confidence interval) for both isolated and blended galaxies. Once combined with the second-order \texttt{FPFS} shear estimator, the shape noise is reduced by $\sim35\%$ for isolated galaxies in simulations with HSC and LSST observational conditions. However, for blended galaxies, the effective number density does not significantly improve with the combination of the two estimators. Based on these results, we recommend exploration of how this framework can further reduce the systematic uncertainties in shear due to PSF leakage and modelling error, and potentially provide improved precision in shear inference in high-resolution space-based images.

CHANCES, the CHileAN Cluster galaxy Evolution Survey, will study the evolution of galaxies in and around ${\sim}$150 massive galaxy clusters, from the local universe out to z=0.45. CHANCES will use the new 4MOST Spectroscopic Survey Facility on the VISTA 4m telescope to obtain spectra for ${\sim}$500,000 galaxies with magnitudes $r_\mathrm{AB} < 20.5$, providing comprehensive spectroscopic coverage of each cluster out to $5r_{200}$. Its wide and deep scope will trace massive and dwarf galaxies from the surrounding filaments and groups to the cores of galaxy clusters, enabling the study of galaxy pre-processing and the role of the evolving environment on galaxy evolution. In this paper we present and characterize the sample of clusters and superclusters to be targeted by CHANCES. We used literature catalogues based on X-ray emission and Sunyaev-Zel'dovich effect to define the cluster sample in a homogeneous way, with attention to cluster mass and redshift, as well as the availability of ancillary data. We calibrated literature mass estimates from various surveys against each other and provide an initial mass estimate for each cluster, which we used to define the radial extent of the 4MOST coverage. We also present an initial assessment of the structure surrounding these clusters based on the redMaPPer red-sequence algorithm as a preview of some of the science CHANCES will enable.

We expand the theoretical framework by Gottlieb el al. (2023), which connects binary merger populations with long and short binary gamma-ray bursts (lbGRBs and sbGRBs), incorporating kilonovae as a key diagnostic tool. We show that lbGRBs, powered by massive accretion disks around black holes (BHs), should be accompanied by bright, red kilonovae. In contrast, sbGRBs - if also powered by BHs - would produce fainter, red kilonovae, potentially biasing against their detection. However, magnetized hypermassive neutron star (HMNS) remnants that precede BH formation can produce jets with power ($P_{\rm NS} \approx 10^{51}\,{\rm erg\,s^{-1}}$) and Lorentz factor ($\Gamma>10$), likely compatible with sbGRB observations, and would result in distinctly bluer kilonovae, offering a pathway to identifying the sbGRB central engine. Recent modeling by Rastinejad et al. (2024) found luminous red kilonovae consistently accompany lbGRBs, supporting lbGRB originating from BH-massive disk systems, likely following a short-lived HMNS phase. The preferential association of sbGRBs with comparably luminous kilonovae argues against the BH engine hypothesis for sbGRBs, while the bluer hue of these KNe provides additional support for an HMNS-driven mechanism. Within this framework, BH-NS mergers likely contribute exclusively to the lbGRB population with red kilonovae. Our findings suggest that GW170817 may, in fact, have been an lbGRB to on-axis observers. Finally, we discuss major challenges faced by alternative lbGRB progenitor models, such as white dwarf-NS or white dwarf-BH mergers and accretion-induced collapse forming magnetars, which fail to align with observed GRB timescales, energies, and kilonova properties.

Ultraluminous X-ray sources (ULXs) are enigmatic sources first discovered in the 1980s in external galaxies. They are characterized by their extraordinarily high X-ray luminosity, which often exceeds $10^{40}\, \rm{erg \; s^{-1}}$. Our study aims to obtain more information about pulsating ULXs (PULXs), first of all, their viewing geometry, since it affects almost all the observables, such as the flux, the pulsed fraction, the polarization degree (PD), and polarization angle (PA). We present a simplified model, which primarily describes the thermal emission from an accreting, highly magnetized neutron star, simulating the contributions of an accretion disk and an accretion envelope surrounding the star magnetosphere, both described by a multicolor blackbody. Numerical calculations are used to determine the flux, PD, and PA of the emitted radiation, considering various viewing geometries. The model predictions are then compared to the observed spectra of two PULXs, M51 ULX-7 and NGC 7793 P13. We identified the best fitting geometries for these sources, obtaining values of the pulsed fraction and the temperature at the inner radius of the disk compatible with those obtained from previous works. We also found that measuring the polarization observables can give considerable additional information on the source.

{We present the radial metallicity gradients within the Galactic thin disc population through main-sequence stars selected on the chemical plane using GALAH DR3 accompanied with Gaia DR3 astrometric data. The [Fe/H], [$\alpha$/Fe] and [Mg/H] radial gradients are estimated for guiding radius as $-0.074\pm 0.006$, $+0.004\pm0.002$, $-0.074\pm0.006$ dex kpc$^{-1}$ and for the traceback early orbital radius as $-0.040\pm0.002$, $+0.003\pm 0.001$, $-0.039\pm 0.002$ dex kpc$^{-1}$ for 66,545 thin-disc stars, respectively. Alteration of the chemical structure within the Galactic disc caused by the radial orbital variations complicates results for the radial metallicity gradient. The effect of radial orbital variations on the metallicity gradients as a function on time indicates the following results: (i) The presence of a gradient along the disc throughout the time for which the model provides similar prediction, (ii) the radial orbital variations becomes more pronounced with the age of the stellar population and (iii) the effect of radial orbital variations on the metallicity gradients is minimal. The effect of radial orbital variations is found to be at most 6\% which does not statistically affect the radial gradient results. These findings contribute to a better understanding of the chemical evolution within the Galactic disc and provide an important basis for further research.

We present radial profiles of luminosity-weighted age, $age_L$, and $\Delta \Sigma_{SFR}$ for various populations of high- and low- mass central and satellite galaxies in the TNG100 cosmological simulation. Using these profiles, we investigate the impact of intrinsic and environmental factors on the radial distribution of star formation. For both central galaxies and satellites, we investigate the effects of black hole mass, cumulative AGN feedback energy, morphology, halo mass, and local galaxy overdensity on the profiles. In addition, we investigate the dependence of radial profiles of the satellite galaxies as a function of the redshifts at which they joined their hosts, as well as the net change in star-forming gas mass since the satellites joined their host. We find that high-mass ($M_*>10^{10.5} M_{\odot}$) central and satellite galaxies show evidence of inside-out quenching driven by AGN feedback. Effects from environmental processes only become apparent in averaged profiles at extreme halo masses and local overdensities. We find that the dominant quenching process for low-mass galaxies ($M_*<10^{10} M_{\odot}$) is environmental, generally occurring at low halo mass and high local galaxy overdensity for low-mass central galaxies and at high host halo masses for low-mass satellite galaxies. Overall, we find that environmental processes generally drive quenching from the outside-in.

With GW170817 being the only multimessenger gravitational wave (GW) event with an associated kilonova (KN) detected so far, there exists a pressing need for realistic estimation of the GW localization uncertainties and rates, as well as optimization of available telescope time to enable the detection of new KNe. For this purpose, we simulate GW events assuming a data-driven, GW-motivated distribution of binary parameters for the LIGO/Virgo/KAGRA (LVK) fourth and fifth observing runs (O4 and O5). For our particular case of estimating KN detection rates in the O4 and O5 runs, we map the binary neutron star (BNS) and neutron star-black hole (NSBH) properties to the optical light curves arising from r-process nucleosynthesis in the ejecta. We use the simulated population of KNe to generate follow-up observing plans, with the primary goal of optimizing detection with the Gravitational Wave Multi-Messenger Astronomy DECam Survey (GW-MMADS). We explore KN detectability as a function of mass, distance, and spin of the binaries. Out of the mergers that produce a KN in our simulations, we expect detectable KNe for DECam-like instruments at a per-year rate of: $1-16$ ($0-1$) for BNS (NSBH) in O4, and $16-165$ ($1-12$) for BNS (NSBH) in O5, using a fiducial exposure time and conditional on the uncertainty on the equation of state (EOS) and volumetric rates of the mergers. Taking into account observability constraints, our scheduler covers the location of the KN $\sim 30-38\%$ of the times for our fiducial EOS. We provide the depths needed to detect a significant fraction of our simulated mergers for the astronomical community to use in their follow-up campaigns.

Numerical QUMOND-simulations of star clusters orbiting in a Galactic disk potential show that the leading tidal arm of open star clusters contains tendentially more members than the trailing arm. However, these type of simulations are performed by solving the field-equations of QUMOND and already become non-practical for star cluster masses at around 5000 Msun. Nearby star clusters have masses of 1000 Msun or ~1000 particles and less/fewer and can currently not be simulated reliably in field-theoretical formulations of MOND. In order to handle particle numbers below the QUMOND-limit the star cluster is simulated in Milgrom-law dynamics (MLD): Milgrom's law is postulated to be valid for discrete systems in vectorial form. In order to suppress the Newtonisation of compact subsystems in the star cluster the gravitational force is softened below particle distances of 0.001 pc ~206 AU. Thus, MLD can only be considered as an approximation of a full MOND-theoretical description of discrete systems which are internally in the MOND regime. The MLD equations of motion are integrated by the standard Hermite scheme generally applied to Newtonian N-body systems, which is extended to solve for the accelerations and jerks associated with Milgrom's law. It is found that the tidal tails of a low-mass star cluster are populated asymmetrically in the MLD-treatment, very similar to the QUMOND simulations of the higher-mass star clusters. In the MLD-simulations the leading tail hosts up to twice as many members than the trailing arm and the low-mass open star cluster dissolves approximately 25% faster than in the respective Newtonian case.

Many known rocky exoplanets are so highly irradiated that their dayside surfaces are molten, and `silicate atmospheres', composed of rock-forming elements, are generated above these lava pools. The compositions of these `lava planet' atmospheres are of great interest because they must be linked to the composition of the underlying rocky interiors. It may be possible to investigate these atmospheres, either by detecting them directly via emission spectroscopy or by observing the dust tails which trail the low mass `catastrophically evaporating planets'. In this work, we develop a simple chemical model of the lava pool--atmosphere system under mass loss, to study its evolution. Mass loss can occur both into space and from the day to the nightside. We show that the system reaches a steady state, where the material in the escaping atmosphere has the same composition as that melted into the lava pool from the mantle. We show that the catastrophically evaporating planets are likely to be in this evolved state. This means that the composition of their dust tails is likely to be a direct trace of the composition of the mantle material that is melted into the lava pool. We further show that, due to the strength of day-to-nightside atmospheric transport, this evolved state may even apply to relatively high-mass planets (>1 Earth Mass). Moreover, the low pressure of evolved atmospheres implies that non-detections may not be due to the total lack of an atmosphere. Both conclusions are important for the interpretation of future observations.

Studying the distribution and properties of ionised gas in outflows driven by AGN is crucial for understanding the feedback mechanisms at play in extragalactic environments. In this study, we explore the connection between ionised outflows traced by rest-frame UV absorption and optical emission lines in GS133, a Compton thick AGN at z = 3.47. We combine observations from the JWST NIRSpec Integral Field Spectrograph (IFS) with archival VLT VIMOS long-slit spectroscopic data, as part of the GA-NIFS project. We perform a multi-component kinematic decomposition of the UV and optical line profiles to derive the physical properties of the absorbing and emitting gas in GS133. Our kinematic decomposition reveals two distinct components in the optical lines. The first component likely traces a rotating disk with a dynamical mass of 2e10 Msun. The second component corresponds to a galaxy-wide, bi-conical outflow, with a velocity of 1000 km/s and an extension of 3 kpc. The UV absorption lines show two outflow components, with bulk velocities v_out = -900 km/s and -1900 km/s, respectively. This characterises GS133 as a mini-BAL system. Balmer absorption lines with similar velocities are tentatively detected in the NIRSpec spectrum. Both photoionisation models and outflow energetics suggest that the ejected absorbing gas is located at 1-10 kpc from the AGN. We use 3D gas kinematic modelling to infer the orientation of the [O III] bi-conical outflow, and find that a portion of the emitting gas resides along our line of sight, suggesting that [O III] and absorbing gas clouds are partially mixed in the outflow. The derived mass-loading factor (i.e. the mass outflow rate divided by the SFR) of 1-10, and the kinetic coupling efficiency (i.e. the kinetic power divided by LAGN) of 0.1-1% per cent suggest that the outflow in GS133 provides significant feedback on galactic scales.

Axions and axion-like particles (ALPs) remain highly motivated extensions to the standard model due to their ability to address open questions such as the relic abundance of dark matter and the strong CP problem. Axions are also capable of undergoing a resonant mixing with photons when the masses of the two fields are roughly equal, producing a wide array of phenomenological consequences. Here, we revisit constraints coming from conversions of the cosmic microwave background (CMB) into axions, which will induce a distortion to the frequency spectrum of the background photons. We introduce a more detailed description for the modeling of the plasma mass of the photon, showcasing how the inclusion of Helium recombination can alter the conversion probability for photons in the Wien tail. Our results include an updated analytic framework, which allows us to define the precise spectral shape of the axion distortion, as well as a numeric component which utilized the code \texttt{CosmoTherm} to fully characterize the distortion, providing a slight increase in the constraining power over the analytics. We also treat for the first time the large-distortion regime for resonant axion-photon conversions. Under the assumption of large-scale primordial magnetic fields near the limit obtained from CMB observations, we find that spectral distortions can probe previously unexplored regions of the axion parameter space.

MICADO, the European Extremely Large Telescope first light imager will feature a dedicated high contrast imaging mode specifically designed for observing and characterizing exoplanets and circumstellar disks. Its improved sensitivity and angular resolution, compared to existing instruments will significantly increase our knowledge on these planetary systems. MICADO will include three classical Lyot coronagraphs, one vector phase-apodized pupil plane (vAPP) and two sparse apertures. After rapidly describing the final design of MICADO high contrast mode, we will describe the current state of development of the coronographic components and the testing of the first Lyot coronagraph prototypes.

The recent discovery of planetesimals orbiting white dwarfs has renewed interest in the final chapters of the evolution of planetary systems. Although observational and theoretical studies have examined the dynamical evolution of these systems, studies of their magnetic star-planet interactions, as powered by unipolar induction, have thus far only been assessed theoretically. This fifth paper of the ROME (Radio Observations of Magnetized Exoplanets) series presents the results of a targeted mini-survey of nine white dwarfs within 25 pc without known stellar mass companions in search of radio emissions generated by magnetic interactions between white dwarfs and their planetary remnants. This $\sim$5 GHz Arecibo radio telescope survey achieved mJy-level sensitivity over $<$1 s integration times. Although no exoplanet-induced stellar radio flares were detected, this is the first survey to search for magnetic star-planet interactions between white dwarfs and planetary companions, cores, or disrupted planetesimals. It is also the most extensive and sensitive radio survey for intrinsic coronal emissions from apparently isolated white dwarfs. The study of radio emissions from white dwarf systems may present a new means to detect and measure DC and DQ magnetic fields, search for white dwarf coronae, characterize the density and spatial distribution of white dwarf magnetospheric plasma, characterize the dynamical and electrical properties of planetary cores, and offer new constraints on the modeling of double degenerate merger events.

The spectroscopic study of mature giant planets and low mass planets (Neptune-like, Earth-like) requires instruments capable of achieving very high contrasts ($10^{-10}-10^{-11}$) at short angular separations. To achieve such high performance on a real instrument, many limitations must be overcome: complex component defects (coronagraph, deformable mirror), optical aberrations and scattering, mechanical vibrations and drifts, polarization effects, etc. To study the overall impact on a complete system representative of high contrast instruments, we have developed a test bench at Paris Observatory, called THD2. In this paper, we focus on the polarization effects that are present on the bench which creates differential aberrations between the two linear polarization states. We compare the recorded beam positions of the two polarization states with the predicted from the Goos-Hänchen and Imbert-Fedorov effects, both of which cause spatial shifts and angular deviations of the beam, longitudinal and transverse respectively. Although these effects have already been studied in the literature from the optical and quantum mechanical points of view, their measurement and impact on a complete optical bench are rather rare, although they are crucial for high-contrast instruments. After describing the Goos-Hänchen and Imbert-Fedorov effects and estimating their amplitude on the THD2 bench, we present the protocol we used to measure these effects of polarization on the light beam. We compare predictions and measurements and we conclude on the most limiting elements on our bench polarization-wise.

Context: The connection between quasi-periodic oscillations (QPOs) and magnetic fields has been investigated across various celestial bodies. Magnetohydrodynamics (MHD) waves have been employed to explain the simultaneous upper and lower kilohertz (kHz) QPOs. Nevertheless, the intricate and undefined formation pathways of twin kHz QPOs present a compelling avenue for exploration. This area of study holds great interest as it provides an opportunity to derive crucial parameters related to compact stars. Aims:We strives to develop a self-consistent model elucidating the radiation mechanism of twin kHz QPOs, subsequently comparing it with observations. Methods: A sample of 28 twin kHz QPOs observed from the X-ray binary 4U 1636--53 are used to compare with the results of the MCMC calculations according to our model of the radiation mechanism of twin kHz QPOs, which is related to twin MHD waves. Results: We obtain twenty-eight groups of parameters of 4U 1636--53 and a tight exponential fit between the flux and the temperature of seed photons to Compton up-scattering and find that the electron temperature in the corona around the neutron star decreases with the increasing temperature of the seed photons. Conclusions: The origin of twin kHz QPOs can be attributed to dual disturbances arising from twin MHD waves generated at the innermost radius of an accretion disc. The seed photons can be transported through a high temperature corona and Compton up-scattered. The variability of the photons with the frequencies of twin MHD waves can lead to the observed twin kHz QPOs.

Understanding of the formation and evolution of the Solar System requires understanding key and common materials found on and in planetary bodies. Mineral mixing and its implications on planetary body formation is a topic of high interest to the planetary science community. Previous work establishes a case for the use of Optical PhotoThermal InfraRed (O-PTIR) in planetary science and introduces and demonstrates the technique's capability to study planetary materials. In this paper, we performed a measurement campaign on granular materials relevant to planetary science, such as minerals found in lunar and martian soils. These laboratory measurements serve to start a database of O-PTIR measurements. We also present FTIR absorption measurements of the materials we observed in O-PTIR for comparison purposes. We find that the O-PTIR technique suffers from granular orientation effects similar to other IR techniques, but in most cases, is is directly comparable to commonly used absorption spectroscopy techniques. We conclude that O-PTIR would be an excellent tool for the purpose of planetary material identification during in-situ investigations on regolith and bedrock surfaces.

We consider the Compton scattering in the optically thick uniform spherical corona around a neutron star in an X-ray binary. In the scattering, the low energy seed photons (0.1 - 2.5 keV) are scattered in low energy electrons (2.5 - 10 keV) in the corona in two conditions, i.e. initial seed photons are scattered in a whole corona and scattered in every layer of the corona that are supposed to be divided into many this http URL the same number of input seed photons, the same corona parameters and the same energy distribution of all photons in the two conditions are considered, the approximately same number of output photons can be obtained, which means that there is approximately a transform invariance of layering the Comptonized corona. Thus the scattering in the layers of a multi-layered corona is approximately equal to the scattering in the whole corona by dividing the whole corona into several this http URL means that Compton scattering for the initial seed photons scattered in a whole optically thick spherical corona with uniformly distributed electrons also can be considered as that the multiple Compton scatterings take place in the layers of a multi-layered corona in order approximately, which can be used to explore some physical process in one part of a corona.

The knee-like structure around 4 PeV is the most striking feature in the cosmic ray energy spectrum, whose origin remains enigmatic. We propose a novel concept of the total logarithmic mass energy spectrum to characterize the knee, taking into account LHAASO measurements of the all-particle energy spectrum and the mean logarithmic mass. The predominant role of proton in the knee formation is unearthed. The case of a mass-dependent knee is ruled out with a significance of 22.9${\sigma}$ and the rigidity-dependent knee feature is revealed. An ankle-like structure stemming from the excess of iron is discovered at 9.7${\pm}$ 0.2 PeV with a significance of 25.9${\sigma}$. Our findings pierce the mist of the puzzling knee for the first time since its discovery.

Icarus is an individual star observed near the macro-critical curve of the MACS J1149 cluster, with the magnification factor estimated to be an order of thousands. Since microlenses near the macro-critical curve influence the number of such high-magnification events, the observed occurrence of Icarus-like events is expected to provide a useful constraint on the properties of microlenses. We first study the mass and mass fraction of microlenses consistent with the observed number of events assuming a single microlens component with a monochromatic mass function, finding that stars that contribute to the intracluster light (ICL) are consistent at the 95% confidence level. We then consider the contribution of primordial black holes (PBHs), which are one of the alternatives to the standard cold dark matter, as microlenses in addition to ICL stars. The derived parameter space indicates that a large abundance of PBHs with a mass around $1\ M_{\odot}$ and a fraction of PBHs to the total dark matter of $f_{\rm PBH} \gtrsim 0.2$ cannot explain the observed number of Icarus-like events and therefore is excluded. The methodology developed in this paper can be used to place tighter constraints on the fraction of PBHs from ongoing and future observations of ultrahigh magnification events.

The Sun is depleted in refractory elements compared to nearby solar twins, which may be linked to the formation of giant or terrestrial planets. Here we present high-resolution, high signal-to-noise spectroscopic data for 17 solar-like stars hosting planets, obtained with Magellan II/MIKE, to investigate whether this depletion is related to planet formation. We derive stellar parameters, including stellar atmosphere, age, radius, mass, and chemical abundances for 22 elements from carbon to europium through line-by-line differential analysis. Our uncertainties range from 0.01 dex for Fe and Si to 0.08 dex for Sr, Y, and Eu. By comparing the solar abundances to those of the 17 stars, we investigate the differential abundance ([X/Fe]$_{\rm solar}$ - [X/Fe]$_{\rm star}$) versus condensation temperature ($T_c$) trend. In particular, we apply Galactic chemical evolution corrections to five solar twins within the full sample. Our results conform to previous studies that the Sun is relatively depleted in refractory compared to volatile elements. For both five solar twins and the rest of solar-like stars, we find that all stars hosting known gas giant planets exhibit negative $T_c$ trend slopes, suggesting that the Sun is relatively depleted in refractory elements compared to similar giant-planet-host stars. Additionally, we find no correlation between $T_c$ trend slopes and the total mass of detected terrestrial planets in each system, suggesting that terrestrial planet formation may not be the cause of refractory element depletion in the Sun.

New emerging flux (NEF) has long been considered a mechanism for solar eruptions, but detailed process remains an open question. In this work, we explore how NEF drives a coronal magnetic configuration to erupt. This configuration is created by two magnetic sources of strengths $M$ and $S$ embedded in the photosphere, one electric-current-carrying flux rope (FR) floating in the corona, and an electric current induced on the photospheric surface by the FR. The source $M$ is fixed accounting for the initial background field, and $S$ changes playing the role of NEF. We introduce the channel function $C$ to forecast the overall evolutionary behavior of the configuration. Location, polarity, and strength of NEF governs the evolutionary behavior of FR before eruption. In the case of $|S/M|<1$ with reconnection occur between new and old fields, the configuration in equilibrium evolves to the critical state, invoking the catastrophe. In this case, if polarities of the new and old fields are opposite, reconnection occurs as NEF is close to FR; and if polarities are the same, reconnection happens as NEF appears far from FR. With different combinations of the relative polarity and the location, the evolutionary behavior of the system gets complex, and the catastrophe may not occur. If $|S/M|>1$ and the two fields have opposite polarity, the catastrophe always takes place; but if the polarities are the same, catastrophe occurs only as NEF is located far from FR; otherwise, the evolution ends up either with failed eruption or without catastrophe at all.

Hub-filament systems (HFSs) are potential sites of massive star formation (MSF). To understand the role of filaments in MSF and the origin of HFSs, we conducted a multi-scale and multi-wavelength observational investigation of the molecular cloud G321.93-0.01. The $^{13}$CO($J$ = 2-1) data reveal multiple HFSs, namely, HFS-1, HFS-2, and a candidate HFS (C-HFS). HFS-1 and HFS-2 exhibit significant mass accretion rates ($\dot{M}_{||}$ $> 10^{-3}$ $M_{\odot}$ yr$^{-1}$) to their hubs (i.e., Hub-1 and Hub-2, respectively). Hub-1 is comparatively massive, having higher $\dot{M}_{||}$ than Hub-2, allowing to derive a relationship $\dot{M}_{||} \propto M^{\beta}_{\rm{hub}}$, with $\beta \sim1.28$. Detection of three compact HII regions within Hub-1 using MeerKAT 1.28 GHz radio continuum data and the presence of a clump (ATL-3), which meets Kauffmann & Pillai's criteria for MSF, confirm the massive star-forming activity in HFS-1. We find several low-mass ALMA cores (1-9 $M_{\odot}$) inside ATL-3. The presence of a compact HII region at the hub of C-HFS confirms that it is active in MSF. Therefore, HFS-1 and C-HFS are in relatively evolved stages of MSF, where massive stars have begun ionizing their surroundings. Conversely, despite a high $\dot{M}_{||}$, the non-detection of radio continuum emission toward Hub-2 suggests it is in the relatively early stages of MSF. Analysis of $^{13}$CO($J$ = 2-1) data reveals that the formation of HFS-1 was likely triggered by the collision of a filamentary cloud about 1 Myr ago. In contrast, the relative velocities ($\gtrsim 1$ km s$^{-1}$) among the filaments of HFS-2 and C-HFS indicate their formation through the merging of filaments.

Internal gravity waves (hereafter IGWs) are one of the mechanisms that can play a key role to redistribute efficiently angular momentum in stars along their evolution. The study of IGWs is thus of major importance since space-based asteroseismology reveals a transport of angular momentum in stars, which is stronger by two orders of magnitude than the one predicted by stellar models ignoring their action or those of magnetic fields. IGWs trigger angular momentum transport when they are damped by heat or viscous diffusion, when they meet a critical layer or when they break. Theoretical prescriptions have been derived for the transport of angular momentum induced by IGWs because of their radiative and viscous dampings and of the critical layers they encounter along their propagation. However, none has been proposed for the transport triggered by their nonlinear breaking. In this work, we aim to derive such a physical and robust prescription, which can be implemented in stellar structure and evolution codes. We adapt an analytical saturation model, which has been developed for IGWs nonlinear convective breaking in the Earth atmosphere and has been successfully compared to in-situ measurements in the stratosphere, to the case of deep spherical stellar interiors. In a first step, we neglect the modification of IGWs by the Coriolis acceleration and the Lorentz force, which are discussed and taken into account in a second step. We derive a complete semi-analytical prescription for the transport of angular momentum by IGWs, which takes into account both their radiative damping and their potential nonlinear breaking because of their convective and vertical shear instabilities. This allows us to bring the physical prescription for the interactions between IGWs and the differential rotation to the same level of realism that the one used in global circulation models for the atmosphere.

The afterglow of gamma-ray bursts (GRBs) has been extensively discussed in the context of shocks generated during an interaction of relativistic outflows with their ambient medium. This process leads to the formation of both a forward and a reverse shock. While the emission from the forward shock, observed off-axis, has been well-studied as a potential electromagnetic counterpart to a gravitational wave-detected merger, the contribution of the reverse shock is commonly overlooked. In this paper, we investigate the contribution of the reverse shock to the GRB afterglows observed off-axis. In our analysis, we consider jets with different angular profiles, including two-component jets, power-law structured jets, Gaussian jets and 'mixed jets' featuring a Poynting-flux-dominated core surrounded by a baryonic wing. We apply our model to GRB 170817A/GW170817 and employ the Markov Chain Monte Carlo (MCMC) method to obtain model parameters. Our findings suggest that the reverse shock emission can significantly contribute to the early afterglow. In addition, our calculations indicate that the light curves observable in future off-axis GRBs may exhibit either double peaks or a single peak with a prominent feature, depending on the jet structure, viewing angle and micro-physics shock parameters.

Fast radio bursts (FRBs) are high-energy, short-duration phenomena in radio astronomy. Identifying their host galaxies can provide insights into their mysterious origins. In this paper, we introduce a novel approach to identifying potential host galaxies in three-dimensional space. We use FRB 20190425A and GW190425 as an example to illustrate our method. Recently, due to spatial and temporal proximity, the potential association of GW190425 with FRB 20190425A has drawn attention, leading to the identification of a likely host galaxy, UGC 10667, albeit without confirmed kilonova emissions. We search for the host galaxy of FRB 20190425A with a full CHIME localization map. Regardless of the validity of the association between GW190425 and FRB 20190425A, we identify an additional potential host galaxy (SDSS J171046.84+212732.9) from the updated GLADE galaxy catalog, supplementing the importance of exploring the new volume. We employed various methodologies to determine the most probable host galaxy of GW190424 and FRB 20190425A, including a comparison of galaxy properties and constraints on their reported observation limits using various Kilonova models. Our analysis suggests that current observations do not definitively identify the true host galaxy. Additionally, the Kilonova models characterized by a gradual approach to their peak are contradicted by the observational upper limits of both galaxies. Although the absence of optical emission detection raises doubts, it does not definitively disprove the connection between GW and FRB.

Context. Dusty debris discs around main sequence stars are observed to vary widely in terms of their vertical thickness. Their vertical structure may be affected by damping in inelastic collisions. Although kinetic models have often been used to study the collisional evolution of debris discs, these models have not yet been used to study the evolution of their vertical structure. Aims. We extend an existing implementation of a kinetic model of collisional evolution to include the evolution of orbital inclinations and we use this model to study the effects of collisional damping in pre-stirred discs. Methods. We evolved the number of particles of different masses, eccentricities, and inclinations using the kinetic model and used Monte Carlo simulations to calculate collision rates between particles in the disc. We considered all relevant collisional outcomes including fragmentation, cratering, and growth. Results. Collisional damping is inefficient if particles can be destroyed by projectiles that are of much lower mass. If that is the case, catastrophic disruptions shape the distributions of eccentricities and inclinations, and their average values evolve slowly and at the same rate for all particle sizes. Conclusions. The critical projectile-to-target mass ratio (Yc) and the collisional timescale jointly determine the level of collisional damping in debris discs. If Yc is much smaller than unity, a debris disc retains the inclination distribution that it is born with for much longer than the collisional timescale of the largest bodies in the disc. Such a disc should exhibit a vertical thickness that is independent of wavelength even in the absence of other physical processes. Collisional damping is efficient if Yc is of order unity or larger. For millimetre-sized dust grains and common material strength assumptions, this requires collision velocities of lower than ~40 m/s. Abridged

Fast Radio Bursts (FRBs) are highly energetic millisecond-duration astrophysical phenomena typically categorized as repeaters or non-repeaters. However, observational limitations may lead to misclassifications, suggesting a larger proportion of repeaters than currently identified. In this study, we leverage unsupervised machine learning techniques to classify FRBs using data from the CHIME/FRB catalog, including both the first catalog and a recent repeater catalog. By employing Uniform Manifold Approximation and Projection (UMAP) for dimensionality reduction and clustering algorithms (k-means and HDBSCAN), we successfully segregate repeaters and non-repeaters into distinct clusters, identifying over 100 potential repeater candidates. Our analysis reveals several empirical relations within the clusters, including the ${\rm log \,}\Delta t_{sc} - {\rm log \,}\Delta t_{rw}$, ${\rm log \,}\Delta t_{sc} - {\rm log \,}T_B$, and $r - \gamma$ correlations, which provide new insights into the physical properties and emission mechanisms of FRBs. This study demonstrates the effectiveness of unsupervised learning in classifying FRBs and identifying potential repeaters, paving the way for more precise investigations into their origins and applications in cosmology. Future improvements in observational data and machine learning methodologies are expected to further enhance our understanding of FRBs.

Accurate calculations of starspot spectra are essential for multiple applications in astronomy. The current standard is to represent starspot spectra by spectra of stars that are cooler than the quiet star regions. This implies approximating a starspot as a non-magnetic 1D structure in radiative-convective equilibrium, parametrizing convective energy transport by mixing length theory. It is the inhibition of convection by the starspot magnetic field that is emulated by using a lower spot temperature relative to the quiet stellar regions. Here, we take a different approach avoiding the approximate treatment of convection and instead self-consistently accounting for the interaction between matter, radiation, and the magnetic field. We simulate spots on G2V, K0V, M0V stars with the 3D radiative magnetohydrodynamics code MURaM and calculate spectra ($R \approx 500$ from 250~nm to 6000~nm) using ray-by-ray radiative transfer with the MPS-ATLAS code. We find that the 1D models fail to return accurate umbral and penumbral spectra on K0V and M0V stars where convective and radiative transfer of energy is simultaneously important over a broad range of atmospheric heights rendering mixing length theory inaccurate. However, 1D models work well for G2V stars, where both radiation and convection significantly contribute to energy transfer only in a narrow region near the stellar surface. Quantitatively, the 1D approximation leads to errors longward of 500 nm of about 50\% for both umbral and penumbral flux contrast relative to quiet star regions on M0V stars, and less than 2\% (for umbrae) and 10\% (for penumbrae) for G2V stars.

The upcoming Square Kilometer Array (SKA) telescope marks a significant step forward in radio astronomy, presenting new opportunities and challenges for data analysis. Traditional visual models pretrained on optical photography images may not perform optimally on radio interferometry images, which have distinct visual characteristics. Self-Supervised Learning (SSL) offers a promising approach to address this issue, leveraging the abundant unlabeled data in radio astronomy to train neural networks that learn useful representations from radio images. This study explores the application of SSL to radio astronomy, comparing the performance of SSL-trained models with that of traditional models pretrained on natural images, evaluating the importance of data curation for SSL, and assessing the potential benefits of self-supervision to different domain-specific radio astronomy datasets. Our results indicate that, SSL-trained models achieve significant improvements over the baseline in several downstream tasks, especially in the linear evaluation setting; when the entire backbone is fine-tuned, the benefits of SSL are less evident but still outperform pretraining. These findings suggest that SSL can play a valuable role in efficiently enhancing the analysis of radio astronomical data. The trained models and code is available at: \url{this https URL}

Massive black holes (MBHs) exist in the Galactic center (GC) and other nearby galactic nuclei. As natural outcome of galaxy mergers, some MBHs may have a black hole (BH) companion. In this paper, assuming that the MBHs in the GC and some nearby galaxies are in binaries with orbital periods ranging from months to years (gravitational-wave frequency $\sim1-100$\,nHz), we investigate the detectability of gravitational-waves from these binary MBHs (BBHs) and constraints on the parameter space for the existence of BBHs in the GC, LMC, M31, M32, and M87, that may be obtained by current/future pulsar timing array (PTA) observations. We find that a BBH in the GC, if any, can be revealed by the Square Kilometer Array PTA (SKA-PTA) if its mass ratio $q\gtrsim10^{-4}-10^{-3}$ and semimajor axis $a\sim20-10^3$\,AU. The existence of a BH companion of the MBH can be revealed by SKA-PTA with $\sim20$-year observations in M31 if $q\gtrsim10^{-4}$ and $a\sim10^2-10^4$\,AU or in M87 if $q\gtrsim10^{-5}$ and $a\sim10^3-2\times10^4$\,AU, but not in LMC and M32 if $q\ll1$. If a number of milli-second stable pulsars with distances $\lesssim0.1-1$\,pc away from the central MBH in the GC, LMC, M32, or M31, can be detected in future and applied to PTAs, the BH companion with mass even down to $\sim100M_\odot$, close to stellar masses, can be revealed by such PTAs. Future PTAs are expected to provide an independent way to reveal BBHs and low-mass MBH companions in the GC and nearby galaxies, improving our understandings of the formation and evolution of MBHs and galaxies.

We present an improved model-independent method for determining the cosmic curvature using the observations of Baryon Acoustic Oscillations (BAOs) and the Hubble parameter. The purpose of this work is to provide insights into late-universe curvature measurements using available observational data and techniques. Thus, we use two sources of BAO data sets, BOSS/eBOSS and latest DESI DR1, and two reconstruction methods, Gaussian process (GP) and artificial neural network (ANN). It is important to highlight that our method circumvents influence induced by the sound horizon in BAO observations and the Hubble constant. Combining BAO data from BOSS/eBOSS plus DESI DR1, we find that the constraint on the cosmic curvature results in $\Omega_K=-0.040^{+0.142}_{-0.145}$ with an observational uncertainty of $1\sigma$ in the framework of GP method. This result changes to $\Omega_K=-0.010^{+0.405}_{-0.424}$ when the ANN method is applied. Further comparative analysis of samples from two BAO data sources, we find that there is almost no difference between the two samples. Although the curvature values obtained from the data samples using DESI DR1 are on the slightly positive and the samples using BOSS/eBOSS are on the slightly negative, these results both report that our universe has a flat spatial curvature within uncertainties, and the precision of constraining the curvature with two BAO samples is almost equal.

$H_0$ tension in the spatially flat $\Lambda$CDM model is reevaluated by employing three sets of non-Planck CMB data, namely WMAP, WMAP+ACT, and WMAP+SPT, in conjunction with DESI BAO data and non-DESI BAO datasets including 6dFGS, SDSS DR7, and SDSS DR16. Our analysis yields $H_0 = 68.86\pm 0.68~\mathrm{km\ s^{-1} Mpc^{-1}}$ with WMAP+DESI BAO, $H_0 = 68.72\pm 0.51~\mathrm{km\ s^{-1} Mpc^{-1}}$ with WMAP+ACT+DESI BAO, and $H_0 = 68.62\pm 0.52~\mathrm{km\ s^{-1} Mpc^{-1}}$ with WMAP+SPT+DESI BAO. The results of non-Planck CMB+DESI BAO exhibit a $3.4\sigma$, $3.7\sigma$, and $3.8\sigma$ tension with the SH0ES local measurement respectively which are around $1 \sigma$ lower in significance for the Hubble tension compared to Planck CMB+DESI BAO. Moreover, by combining DESI BAO data+non-Planck CMB measurements, we obtain a more stringent constraint on the Hubble constant compared to non-DESI BAO data+non-Planck CMB data, as well as reducing the significance of the Hubble tension.

Magnetohydrodynamic (MHD) waves, playing a crucial role in transporting energy through the solar atmosphere, manifest in various chromospheric structures. Here, we investigated MHD waves in a long-lasting dark fibril using high-temporal-resolution (2~s cadence) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 6 (centered at 1.25~mm). We detected oscillations in brightness temperature, horizontal displacement, and width at multiple locations along the fibril, with median periods and standard deviations of $240\pm114$~s, $225\pm102$~s, and $272\pm118$~s, respectively. Wavelet analysis revealed a combination of standing and propagating waves, suggesting the presence of both MHD kink and sausage modes. Less dominant than standing waves, oppositely propagating waves exhibit phase speeds (median and standard deviation of distributions) of $74\pm204$~km/s, $52\pm197$~km/s, and $28\pm254$~km/s for the three observables, respectively. This work demonstrates ALMA's capability to effectively sample dynamic fibrillar structures, despite previous doubts, and provides valuable insights into wave dynamics in the upper chromosphere.

The Laser Interferometer Space Antenna (LISA) will be the first space-based gravitational wave (GW) observatory. It will measure gravitational wave signals in the frequency regime from 0.1 mHz to 1 Hz. The success of these measurements will depend on the suppression of the various instrument noises. One important noise source in LISA will be tilt-to-length (TTL) coupling. Here, it is understood as the coupling of angular jitter, predominantly from the spacecraft, into the interferometric length readout. The current plan is to subtract this noise in-flight in post-processing as part of a noise minimization strategy. It is crucial to distinguish TTL coupling well from the GW signals in the same readout to ensure that the noise will be properly modeled. Furthermore, it is important that the subtraction of TTL noise will not degrade the GW signals. In the present manuscript, we show on simulated LISA data and for four different GW signal types that the GW responses have little effect on the quality of the TTL coupling fit and subtraction. Also, the GW signal characteristics were not altered by the TTL coupling subtraction.

We investigate how stellar feedback from the first stars (Population III) distributes metals through the interstellar and intergalactic medium using the star-by-star cosmological hydrodynamics simulation, Aeos. We find that energy injected from the supernovae of the first stars is enough to expel a majority of gas and injected metals beyond the virial radius of halos with mass $M_* \lesssim 10^7$ M$_\odot$, regardless of the number of supernovae. This prevents self-enrichment and results in a non-monotonic increase in metallicity at early times. Most minihalos ($M \gtrsim 10^5 \, \rm M_\odot$) do not retain significant fractions of the yields produced within their virial radii until they have grown to halo masses of $M \gtrsim 10^7 \, \rm M_\odot$. The loss of metals to regions well beyond the virial radius delays the onset of enriched star formation and extends the period that Population III star formation can persist. We also explore the contributions of different nucleosynthetic channels to 10 individual elements. On the timescale of the simulation (lowest redshift $z=14.3$), enrichment is dominated by core-collapse supernovae for all elements, but with a significant contribution from asymptotic giant branch winds to the s-process elements, which are normally thought to only be important at late times. In this work, we establish important mechanisms for early chemical enrichment which allows us to apply Aeos in later epochs to trace the evolution of enrichment during the complete transition from Population III to Population II stars.

Examining reflected light from exoplanets aids in our understanding of the scattering properties of their atmospheres and will be a primary task of future flagship space- and ground-based telescopes. We introduce an enhanced capability of Planetary Intensity Code for Atmospheric Scattering Observations (PICASO), an open-source radiative transfer model used for exoplanet and brown dwarf atmospheres, to produce reflected light phase curves from three-dimensional atmospheric models. Since PICASO is coupled to the cloud code Virga, we produce phase curves for different cloud condensate species and varying sedimentation efficiencies (fsed) and apply this new functionality to Kepler-7b, a hot Jupiter with phase curve measurements dominated by reflected starlight. We model three different cloud scenarios for Kepler-7b: MgSiO3 clouds only, Mg2SiO4 clouds only, and Mg2SiO4, Al2O3, and TiO2 clouds. All our Virga models reproduce the cloudy region west of the substellar point expected from previous studies, as well as clouds at high latitudes and near the eastern limb, which are primarily composed of magnesium silicates. Al2O3 and TiO2 clouds dominate near the substellar point. We then compare our modeled reflected light phase curves to Kepler observations and find that models with all three cloud condensate species and low sedimentation efficiencies (0.03 - 0.1) match best, though our reflected light phase curves show intensities approximately one-third of those observed by Kepler. We conclude that a better understanding of zonal transport, cloud radiative feedback, and particle scattering properties is needed to further explain the differences between the modeled and observed reflected light fluxes.

Context. Quasar outflows are key players in the feedback processes that influence the evolution of galaxies and the intergalactic medium. The chemical abundance of these outflows provides crucial insights into their origin and impact. Aims. To determine the absolute abundances of nitrogen and sulfur and the physical conditions of the outflow seen in quasar 3C298. Methods. We analyze archival spectral data from the Hubble Space Telescope (HST) for 3C298. We measure Ionic column densities from the absorption troughs and compare the results to photoionization predictions made by the Cloudy code for three different spectral energy distributions (SED), including MF87, UVsoft, and HE0238 SEDs. We also calculate the ionic column densities of excited and ground states of N iii to estimate the electron number density and location of the outflow using the Chianti atomic database. Results. The MF87, UVsoft, and HE0238 SEDs yield nitrogen and sulfur abundances at super-solar, solar, and sub-solar values, respectively, with a spread of 0.4 to 3 times solar. Additionally, we determined an electron number density of log(ne) greater than 3.3 cm-3, with the outflow possibly extending up to a maximum distance of 2.8 kpc. Conclusions. Our results indicate solar metallicity within a 60 percent uncertainty range, driven by variations in the chosen SED and photoionization models. This study underscores the importance of SEDs impact on determining chemical abundances in quasars outflows. These findings highlight the necessity of considering a wider range of possible abundances, spanning from sub solar to super solar values.

We study the structure, interstellar absorption, color-magnitude diagrams, kinematics, and dynamical state of embedded star clusters in the star-forming region associated with the giant molecular cloud G174+2.5. Our investigation is based on photometric data from the UKIDSS Galactic Plane Survey catalog and astrometric data from the Gaia DR3 catalogs. First, we recover all the known embedded clusters and candidate clusters in the region using surface density maps. Then, for the detected clusters, we determine their general parameters: the center positions, radii, number of stars, and reddening. To evaluate the reddening, we use both the NICEST algorithm and the Q-method. Both methods produce consistent extinction maps in the regions of the four studied clusters. However, the Q-method yields a much smaller color scatter in the CMD. For four clusters in particular (S235~North-West, S235~A-B-C, S235~Central, and S235~East1+East2), we were able to compute individual membership probabilities, the cluster distances, the cluster masses, and their average proper motions. By building on these results, we have studied the clusters' kinematics and dynamics. Moreover, we estimate the mass of the gas component and the star formation efficiency (SFE) in the regions of these four clusters. Finally, we provide an estimate of the total energy of the stellar and gas components in the area of these four clusters to determine whether the clusters are bound (here we consider a `cluster' as the system `stars + gas'). The gravitational bound strongly depends on the region for which we estimate the gas mass. If we consider the mass of the entire cloud, all these four clusters turn out to be bound.

Recent ALMA observations discovered consequent amounts (i.e., up to a few $10^{-1}\; \rm M_\oplus$) of CO gas in debris disks that were expected to be gas-free. This gas is in general estimated to be mostly composed of CO, C, and O (i.e., $\rm H_2$-poor), unlike the gas present in protoplanetary disks ($\rm H_2$-rich). At this stage, the majority of planet formation already occurred, and giant planets might be evolving in these disks. While planets have been directly observed in debris disks (e.g., $\beta$ Pictoris), their direct observations are challenging due to the weak luminosity of the planets. In this paper, with the help of hydrodynamical simulations (with FARGO3D) coupled with a radiative transfer code (RADMC-3D) and an observing tool (CASA), we show that planet-gas interactions can produce observable substructures in this late debris disk stage. While it is tricky to observe gaps in the CO emission of protoplanetary disks, the unique properties of the gaseous debris disks allow us to observe planetary gaps in the gas. Depending on the total mass of the gaseous debris disk, kinks can also be observed. We derive a simple criterion to estimate in which conditions gaps would be observable and apply it to the known gaseous debris disk surrounding HD138813. In our framework, we find that planets as small as $0.5 \; \rm M_J$ can produce observable gaps and investigate under which conditions (i.e., gas and planets characteristics) the substructure become observable with ALMA. The first observations of planet-gas interactions in debris disks can lead to a new way to indirectly detect exoplanets, reaching a population that could not be probed before, such as giant planets that are too cold to be detected by direct imaging.

An established method measuring the hydrogen ionisation fraction in shock excited gas is the BE99 method, which utilises six bright forbidden emission lines of [SII]6716, 6731, [NII]6548, 6583, and [OI]6300, 6363. We aim to extent the BE99 method by including more emission lines in the blue and near-infrared part of the spectrum ($\lambda$ = 3500-11000A), and considering higher hydrogen ionisation fractions ($x_e > 0.3$). In addition, we investigate how a non-equilibrium state of the gas and the presence of extinction influence the BE99 technique. We find that plenty additional emission line ratios can in principle be exploited as extended curves (or stripes) in the ($x_e, T_e$)-diagram. If the BE99 equilibrium is reached and extinction is corrected for, all stripes overlap in one location in the ($x_e, T_e$)-diagram indicating the existing gas parameters. The application to the Par Lup 3-4 outflow shows that the classical BE99 lines together with the [NI]5198+5200 lines do not meet in one locationin the ($x_e, T_e$)-diagram. This indicates that the gas parameters derived from the classical BE99 method are not fully consistent with other observed line ratios. A multi-line approach is necessary to determine the gas parameters. From our analysis we derive $n_e \sim$ 45 000 cm^-3 - 53000 cm^-3 , $T_e$ = 7600K - 8000K, and $x_e \sim$ 0.027 - 0.036 for the Par Lup 3-4 outflow. For the 244-440 Proplyd we were able to use the line ratios of [SII]6716+6731, [OI]6300+6363, and [OII]7320, 7330 in the BE99 diagram to estimate the ionisation fraction at knot E3 ($x_e = 0.58 \pm 0.05$). In conclusion, exploiting new line ratios reveals more insights on the state of the gas. Our analysis indicates, however, that a multi-line approach is more robust in deriving gas parameters, especially for high density gas.

A considerable number of asymptotic giant branch (AGB) stars exhibit UV excess and/or X-ray emission indicative of the presence of a binary companion. AGB stars are so bright that they easily outshine their companions, making almost impossible their identification. Y Gem has been known to be a far-UV- and X-ray-bright AGB star for some decades now, but the nature of its companion, whether it is a main-sequence star or a white dwarf (WD) in a symbiotic system (SySt), is disputed. Our goal is to uncover the true nature of Y Gem to help us peer into the possible misidentified population of SySts. Multi-wavelength IR, optical, UV and X-ray observations have been analyzed to investigate the properties of the stellar components and accretion process in Y Gem. In particular, an optical spectrum of Y Gem is presented here for the first time, while X-ray data are interpreted by means of reflection models produced by an accretion disk and material in its vicinity. The optical spectrum exhibits the typical saw-shaped features of molecular absorptions in addition to narrow recombination and forbidden emission lines. The presence of the emission lines and the analysis of the extinction-corrected UV spectrum suggest a hot component with $T_\mathrm{eff}\approx$60,000 K, $L$=140 L$_{\odot}$, and $R$=0.11 R$_{\odot}$, very likely an accreting WD. The late component is found to be an 1.1 M$_\odot$ AGB star with $T_\mathrm{eff}$=3350 K and $R$=240 R$_\odot$. Using IR, optical, UV, and X-ray data, we found that Y Gem is a S-type SySt whose compact component is accreting at an estimated mass accretion rate of $\dot{M}_\mathrm{acc}=2.3\times10^{-7}$ M$_\odot$ yr$^{-1}$. At such accretion rate, the accreting WD has reached the stable and steady burning phase where no recurrent events are expected.

The molecular gas in the interstellar medium (ISM) of star-forming galaxy populations exhibits diverse physical properties. We investigate the $^{12}$CO excitation of twelve dusty, luminous star-forming galaxies at $z \sim 2-4$ by combining observations of the $^{12}$CO from $J_{\rm up} = 1$ to $J_{\rm up} = 8$. The spectral line energy distribution (SLED) has a similar shape to NGC 253, M82, and local ULIRGs, with much stronger excitation than the Milky Way inner disc. By combining with resolved dust continuum sizes from high-resolution $870$-$\mu$m ALMA observations and dust mass measurements determined from multi-wavelength SED fitting, we measure the relationship between the $^{12}$CO SLED and probable physical drivers of excitation: star-formation efficiency, the average intensity of the radiation field $\langle U\rangle$, and the star-formation rate surface density. The primary driver of high-$J_{\rm up}$ $^{12}$CO excitation in star-forming galaxies is star-formation rate surface density. We use the ratio of the CO($3-2$) and CO($6-5$) line fluxes to infer the CO excitation in each source and find that the average ratios for our sample are elevated compared to observations of low-redshift, less actively star-forming galaxies and agree well with predictions from numerical models that relate the ISM excitation to the star-formation rate surface density. The significant scatter in the line ratios of a factor $\approx 3$ within our sample likely reflects intrinsic variations in the ISM properties which may be caused by other effects on the excitation of the molecular gas, such as cosmic ray ionization rates and mechanical heating through turbulence dissipation.

Supersoft X-ray sources (SSS) are thought to be accreting white dwarfs (WDs) in close binary systems, with thermonuclear burning on their surfaces. The SSS RX J$0513.9-6951$ in the Large Magellanic Cloud (LMC) exhibits cyclic variations between optical low and high states, which are anti-correlated with its X-ray flux. This behaviour is believed to result from the periodic expansion and contraction of the WD due to variations in the accretion rate in the system. We analyse eight high-resolution XMM and six grating Chandra spectra of RX J$0513.9-6951$ with our grid of model atmosphere spectra of hot WDs computed under the assumption of local thermodynamic equilibrium. Our aim is to test a contraction model of the source variability by tracking the evolution of the WD properties. The used grid of hot WD model atmospheres spans a wide range of effective temperatures ($T_{\rm eff}=100-1000\,\rm kK$ in steps of $25\,\rm kK$) and eight values of surface gravity $\log g$. The LMC chemical composition was assumed. The obtained fitting parameters ($T_{\rm eff}$, $\log g$, and bolometric luminosity $L$) evolve on the $T_{\rm eff}- \log g$ and $T_{\rm eff}- L$ planes. This evolution follows the model tracks of WDs with masses of $1.05-1.15\,M_{\odot}$ and thermonuclear burning on the surface. The analysis has showed that the optical brightness of the system is lower when the WD is larger, more luminous, and more effectively illuminates the accretion disc. These results contradict the contraction model, which predicts the opposite behaviour of the source. We use a model, that assumes that the far UV/soft X-ray flux is reprocessed into the optical band due to multiple scattering in the cloud system above the accretion disc. More significant illumination can lead to rarefying of the cloud slab, thereby reducing the reprocessing efficiency and making the source fainter in the optical band.

We present the large-scale distribution and kinematics of cold molecular gas across the compact galaxy group Stephan's Quintet, based on CO(2-1) observations performed with the Atacama Compact Array (ACA) and CO(1-0) data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We find coherent structures of molecular gas associated with the galaxies and intra-group medium, which follow the distribution of warm H$_{2}$ previously seen with the James Webb Space Telescope (JWST). CO is associated with a ridge of shocked gas that crosses the galaxy group, and with a spiral arm of the intruding galaxy NGC7318b, which interacts with the intra-group medium along the ridge. Although the ridge contains widespread shocks, turbulent gas, and warm H$_{2}$, the CO lines are narrower than elsewhere in Stephan's Quintet (FWHM~25-65 km/s), indicative of settled cold gas. At a distinctly different velocity, CO is found in the active galaxy NGC7319 and Northern star-forming region SQ-A. A bridge of turbulent molecular gas connects NGC7319 with the ridge, covering a gap of ~700 km/s between these structures. The gas excitation ranges from $L'_{\rm CO(2-1)}$/$L'_{\rm CO(1-0)}$ ~ 0.3 in the bridge and SQ-A, to ~0.5 along the ridge, to near unity in the center of NGC7319. We also detect either a molecular outflow or turbulent molecular gas associated with the radio source in NGC7319. These ACA data are part of a program with the Atacama Large Millimeter/submillimeter Array (ALMA) and JWST to study molecular gas physics from the largest to the smallest scales across the intra-group medium of Stephan's Quintet.

The Hydrogen Lyman-alpha (Lya) line shows a large variety of shapes which is caused by factors at different scales, from the interstellar medium to the intergalactic medium. This work aims to provide a systematic inventory and classification of the spectral shapes of Lya emission lines to understand the general population of high-redshift Lya emitting galaxies (LAEs). Using the data from the MUSE eXtremely Deep Field, we select 477 galaxies at z=2.8-6.6. We develop a method to classify Lya emission lines in four spectral and three spatial categories, by combining a spectral analysis with a narrow-band image analysis. We measure spectral properties, such as the peak separation and the blue-to-total flux ratio. To ensure a robust sample for statistical analysis, we define a final unbiased sample of 206 galaxies by applying thresholds for signal-to-noise ratio, peak separation, and Lya luminosity. Our analysis reveals that between 32% and 51% of the galaxies exhibit double-peaked profiles. This fraction seems to evolve dependently with the Lya luminosity, while we don't notice a severe decrease of this fraction with redshift. A large amount of these double-peaked profiles shows blue-dominated spectra, suggesting unique gas dynamics and inflow characteristics in some high-redshift galaxies. Among the double-peaked galaxies, 4% are spurious detections. Around 20% out of the 477 sources of the parent sample lie in a complex environment, meaning there are other clumps or galaxies at the same redshift within a distance of 30kpc. Our results suggest that the Lya double-peak fraction may trace the evolution of IGM attenuation, but faintest galaxies are needed to be observed at high redshift. In addition, it is crucial to obtain secure systemic redshifts for LAEs to better constrain the nature of the double-peaks.

Parameter inference is a crucial task in modern cosmology that requires accurate and fast computational methods to handle the high precision and volume of observational datasets. In this study, we explore a hybrid vision transformer, the Convolution vision Transformer (CvT), which combines the benefits of vision transformers and convolutional neural networks. We use this approach to infer the $\Omega_m$ and $\sigma_8$ cosmological parameters from simulated dark matter and halo fields. Our experiments indicate that the constraints on $\Omega_m$ and $\sigma_8$ obtained using CvT are better than the traditional vision transformer (ViT) and CNN, using either dark matter or halo fields. For CvT, pretraining on dark matter fields proves advantageous for improving constraints using halo fields compared to training a model from the beginning. However, ViT and CNN do not show these benefits. The CvT is more efficient than ViT since, despite having more parameters, it requires a training time similar to that of ViT and has similar inference times. The code is available at \url{this https URL}.

Thermal radiation of neutron stars in soft X-ray transients (SXTs) in a quiescent state is believed to be powered by the heat deposited in the stellar crust due to nuclear reactions during accretion. Confronting observations of this radiation with simulations helps to verify theoretical models of the dense matter in neutron stars. We simulate the thermal evolution of the SXTs with theoretical models of the equation of state and composition of the accreted crust. The new family of such models were recently developed within a thermodynamically consistent approach by modeling the nuclear evolution of an accreted matter as it sinks toward the stellar center, starting from representative thermonuclear ash compositions. The crust cooling curves computed with the traditional and modern theory are compared with observations of SXTs MXB 1659-29 and IGR J17480-2446. We show that the new and traditional models of the accreted neutron star crusts are similar in their capability to explain the thermal evolution of neutron stars in SXTs. Both kinds of models require inclusion of additional ingredients not supplied by the current theory, such as the shallow heating and variation of thermal conductivity, to fit observations.

The 21 cm signal from the Epoch of Reionization will be observed with the up-coming Square Kilometer Array (SKA). SKA should yield a full tomography of the signal which opens the possibility to explore its non-Gaussian properties. How can we extract the maximum information from the tomography and derive the tightest constraint on the signal? In this work, instead of looking for the most informative summary statistics, we investigate how to combine the information from two sets of summary statistics using simulation-based inference. To this purpose, we train Neural Density Estimators (NDE) to fit the implicit likelihood of our model, the LICORICE code, using the Loreli II database. We train three different NDEs: one to perform Bayesian inference on the power spectrum, one to do it on the linear moments of the Pixel Distribution Function (PDF) and one to work with the combination of the two. We perform $\sim 900$ inferences at different points in our parameter space and use them to assess both the validity of our posteriors with Simulation-based Calibration (SBC) and the typical gain obtained by combining summary statistics. We find that our posteriors are biased by no more than $\sim 20 \%$ of their standard deviation and under-confident by no more than $\sim 15 \%$. Then, we establish that combining summary statistics produces a contraction of the 4-D volume of the posterior (derived from the generalized variance) in 91.5 % of our cases, and in 70 to 80 % of the cases for the marginalized 1-D posteriors. The median volume variation is a contraction of a factor of a few for the 4D posteriors and a contraction of 20 to 30 % in the case of the marginalized 1D posteriors. This shows that our approach is a possible alternative to looking for sufficient statistics in the theoretical sense.

An analysis of a historical compilation of Hubble-Lemaître constant values ($H_0$: 163 data points measured between 1976 and 2019) assuming the standard cosmological model gives a $\chi^2$ value of the dispersion with respect to the weighted average of 580, much larger than the number of points, which has an associated probability that is very low. This means that Hubble tensions were always present in the literature, due either to the underestimation of statistical error bars associated with the observed parameter measurements, or to the fact that systematic errors were not properly taken into account in many of the measurements. The fact that the underestimation of error bars for $H_0$ is so common might explain the apparent 4.4-sigma discrepancy by Riess et al. As a matter of fact, more recent precise $H_0$ measurements with JWST data by Freedman et al. using standard candles in galaxies find there is no tension with CMBR data, possibly indicating that previously Riess et al. had underestimated their errors. Here we have carried out a recalibration of the probabilities. The tension of 4.4-$\sigma $, estimated between the local Cepheid-supernova distance ladder and cosmic microwave background (CMB) data, is indeed a 2.1-$\sigma $ tension in equivalent terms of a normal distribution, with an associated probability $P$ = 0.036 (1 in 28). This can be increased to an equivalent tension of 2.5-$\sigma $ in the worst cases of claimed 6-$\sigma $ tension, which may in any case happen as a random statistical fluctuation. If Hubble tensions were always present in the literature, and present day tensions are not more important than previous ones, why, then, is there so much noise and commotion surrounding Hubble tension after 2019? It is suggested here that this obeys a sociological phenomenon of ``groupthink''.

The significance of statistical physics concepts such as entropy extends far beyond classical thermodynamics. We interpret the similarity between partitions in statistical mechanics and partitions in Bayesian inference as an articulation of a result by Jaynes (1957), who clarified that thermodynamics is in essence a theory of information. In this, every sampling process has a mechanical analogue. Consequently, the divide between ensembles of samplers in parameter space and sampling from a mechanical system in thermodynamic equilibrium would be artificial. Based on this realisation, we construct a continuous modelling of a Bayes update akin to a transition between thermodynamic ensembles. This leads to an information theoretic interpretation of Jazinsky's equality, relating the expenditure of work to the influence of data via the likelihood. We propose one way to transfer the vocabulary and the formalism of thermodynamics (energy, work, heat) and statistical mechanics (partition functions) to statistical inference, starting from Bayes' law. Different kinds of inference processes are discussed and relative entropies are shown to follow from suitably constructed partitions as an analytical formulation of sampling processes. Lastly, we propose an effective dimension as a measure of system complexity. A numerical example from cosmology is put forward to illustrate these results.

A nearby supernova will carry an unprecedented wealth of information about astrophysics, nuclear physics, and particle physics. Because supernova are fundamentally neutrino driven phenomenon, our knowledge about neutrinos -- particles that remain quite elusive -- will increase dramatically with such a detection. One of the biggest open questions in particle physics is related to the masses of neutrinos. Here we show how a galactic supernova provides information about the masses of each of the three mass eigenstates \emph{individually}, at some precision, and is well probed at JUNO. This information comes from several effects including time delay and the physics within the supernova. The time delay feature is strongest during a sharp change in the flux such as the neutronization burst; additional information may also come from a QCD phase transition in the supernova or if the supernova forms a black hole. We consider both standard cases as dictated by local oscillation experiments as well as new physics motivated scenarios where neutrino masses may differ across the galaxy.

Cosmological correlators encode rich information about physics at the Hubble scale and may exhibit characteristic oscillatory signals due to the exchange of massive particles. Although many 1-loop processes, especially those that break de Sitter (dS) boosts, can generate significant leading signals for various particle models in cosmological collider physics, the precise results for these correlators or their full signals remain unknown due to the lack of symmetry. In this work, we apply the method of partial Mellin-Barnes (PMB) representation to the calculation of cosmological correlators at the loop level. As a first step, we use the PMB representation to calculate four-point cosmological correlators with bubble topology. We find that both the nonlocal and local signals arise from the factorized part, validating the cutting rules proposed in previous work, and are free from UV divergence. Furthermore, the UV divergence originates solely from the background piece and can be manifestly canceled by introducing the appropriate counterterm, similar to the procedure in flat spacetime. We also demonstrate how to renormalize the 1-loop correlators in Mellin space. After a consistency check with known results for the covariant case, we provide new analytical results for the signals generated from a nontrivial dS-boost-breaking bubble.

Determining the bubble wall velocity in first-order phase transitions is a challenging task, requiring the solution of (coupled) equations of motion for the scalar field and Boltzmann equations for the particles in the plasma. The collision terms appearing in the Boltzmann equation present a prominent source of uncertainty as they are often known only at leading log accuracy. In this paper, we derive upper and lower bounds on the wall velocity, corresponding to the local thermal equilibrium and ballistic limits. These bounds are completely independent of the collision terms. For the ballistic approximation, we argue that the inhomogeneous plasma temperature and velocity distributions across the bubble wall should be taken into account. This way, the hydrodynamic obstruction previously observed in local thermal equilibrium is also present for the ballistic approximation. This is essential for the ballistic approximation to provide a lower bound on the wall velocity. We use a model-independent approach to study the behaviour of the limiting wall velocities as a function of a few generic parameters, and we test our developments in the singlet extended Standard Model.

Measurement of gravitational waves can give precision tests of the nature of black holes and compact objects. In this work, we test Giddings' non-violent non-locality proposal, which posits that quantum information is transferred via a nonlocal interaction that generates metric perturbations around black holes. In contrast to firewalls, these quantum fluctuations would be spread out over a larger distance range up to a Schwarzschild radius away. In this letter, we model the modification to the gravitational waveform from non-violent non-locality. We modify the nonspinning EOBNRv2 effective one body waveform to include metric perturbations that are due to a random Gaussian process. We find that the waveform exhibits random deviations which are particularly important in the late inspiral-plunge phase. We find an optimal dephasing parameter for detecting this effect with a principal component analysis. This is particularly intriguing because it predicts random phase deviations across different gravitational wave events, providing theoretical support for hierarchical tests of general relativity. We estimate the constraint on the perturbations in non-violent non-locality with events for the LIGO-Virgo network and for a third generation network.

We analyze 192 sets of binary black hole merger data in eccentric orbits obtained from RIT, decomposing the radiation energy into three distinct phases through time: inspiral, late inspiral to merger, and ringdown. Our investigation reveals a universal oscillatory behavior in radiation energy across these phases, influenced by varying initial eccentricities. From a post-Newtonian perspective, we compare the orbital average of radiation energy with the non-orbital average during the inspiral phase. Our findings indicate that the oscillatory patterns arise from non-orbital average effects, which disappear when orbital averaging is applied. This orbital effect significantly impacts the mass, spin, and recoil velocity of the merger remnant, with its influence increasing as the initial eccentricity rises. Specifically, in the post-Newtonian framework, the amplitudes of oscillations for mass, spin, and recoil velocity at ${e_t}_0 = 0.5$ (initial temporal eccentricity of PN) are enhanced by approximately 10, 5, and 7 times, respectively, compared to those at ${e_t}_0 = 0.1$. For a circular orbit, where ${e_t}_0 = 0.0$, the oscillations vanish entirely. These findings have important implications for waveform modeling, numerical relativity simulations, and the characterization of binary black hole formation channels.

We investigate the impact of fuzzy dark matter (FDM) on supermassive black holes (SMBHs) characterized by a spherical charge distribution. This work introduces a new class of spherically symmetric, self-gravitational relativistic charged models for FDM haloes, using the Einasto density model. This study enables the dark matter (DM) to appear as the matter ingredient, which constructs the black hole and extends the non-commutative mini black hole stellar solutions. By considering the charged anisotropic energy-momentum tensor with an equation of state (EoS) $p_{r}=-\rho$, we explore various black hole solutions for different values of the Einasto index and mass parameter. Our approach suggests that the central density of the resulting black hole model mimics the usual de Sitter core. Furthermore, we discuss the possibility of constructing a charged self-gravitational droplet by replacing the above-mentioned EoS with a non-local one. However, under these circumstances, the radial pressure is observed to be negative. Ultimately, we consider various possibilities of constructing DM black holes, featuring intermediate masses that could evolve into galaxies. Consequently, some of these theoretical models have the potential to replace the usual black hole solutions of the galactic core. Simultaneously, these models are physically beneficial for being comprised of the fundamental matter component of the cosmos. Due to the outcomes of this paper, we would be able to study the connection between BH and DM by formulating stable stellar structures featuring fuzzy mass distributions derived from the Einasto distribution of DM halos.

BabyIAXO is the intermediate stage of the International Axion Observatory (IAXO) to be hosted at DESY. Its primary goal is the detection of solar axions following the axion helioscope technique. Axions are converted into photons in a large magnet that is pointing to the sun. The resulting X-rays are focused by appropriate X-ray optics and detected by sensitive low-background detectors placed at the focal spot. The aim of this article is to provide an accurate quantitative description of the different components (such as the magnet, optics, and X-ray detectors) involved in the detection of axions. Our efforts have focused on developing robust and integrated software tools to model these helioscope components, enabling future assessments of modifications or upgrades to any part of the IAXO axion helioscope and evaluating the potential impact on the experiment's sensitivity. In this manuscript, we demonstrate the application of these tools by presenting a precise signal calculation and response analysis of BabyIAXO's sensitivity to the axion-photon coupling. Though focusing on the Primakoff solar flux component, our virtual helioscope model can be used to test different production mechanisms, allowing for direct comparisons within a unified framework.

This document compiles results obtained from the test campaign of the European Moon Rover System (EMRS) project. The test campaign, conducted at the Planetary Exploration Lab of DLR in Wessling, aimed to understand the scope of the EMRS breadboard design, its strengths, and the benefits of the modular design. The discussion of test results is based on rover traversal analyses, robustness assessments, wheel deflection analyses, and the overall transportation cost of the rover. This not only enables the comparison of locomotion modes on lunar regolith but also facilitates critical decision-making in the design of future lunar missions.

One of the theoretical motivations behind the belief that black holes as described by general relativity exist in nature is that it is hard to find matter configurations that mimic their properties, especially their compactness. One of the classic results that goes in this direction is the so-called Buchdahl limit: a bound for the maximum compactness that, under a few assumptions, static fluid spheres in hydrostatic equilibrium can possibly have. We highlight two of the main assumptions that could be violated in physically realistic situations: i) isotropy and ii) an outward-decreasing monotonicity of the density profile, which, as we discuss in detail, can be understood as a form of energy condition. We construct a pair of toy models that exemplify how the Buchdahl limit can be overcome if any of these two assumptions is individually relaxed. In particular, we show that relaxing the monotonicity assumption alone yields a new, less restrictive compactness limit as long as the energy density is not allowed to become negative. If negative energies are permitted, the compactness of these toy models can be as close to the black hole limit as desired. We also discuss how these toy models represent some of the main features of realistic systems, and how they could be extended to find more refined models.

In this paper, we evaluate the potential of multiband gravitational wave observations to constrain the properties of static dark matter spikes around intermediate-mass ratio inspirals. The influence of dark matter on the orbital evolution of the compact binary is incorporated as a correction to the inspiral Newtonian gravitational waveform. We show that the observations from the proposed space-based detector GWSat, sensitive within the deci-Hz frequency band, when combined with that of the third-generation ground-based detectors like the Einstein Telescope and Cosmic Explorer, will produce significantly improved error estimates for all parameters. In particular, our results demonstrate that the joint multiband approach substantially refines the bounds on the dark matter spike parameters-namely, the power-law index and spike density-by factors of approximately $10^6$ and $10^3$, respectively, compared to observations employing only third-generation gravitational wave detectors.

We present in this work the first assessment of the previously unexplored effect of positronium formation on the value of the effective number of neutrino species in the Standard Model, $N_{\mathrm{eff}}^{\mathrm{SM}}$. We find that the expected impact on $N_{\mathrm{eff}}^{\mathrm{SM}}$ crucially depends on the temperature at which positronium equilibrates as well as the rate at which this equilibration happens. The dominant factor limiting the formation process is the melting of positronium at high temperatures driven by Debye screening of the electrostatic potential and scatterings with real photons. Using simple physical arguments, we estimate that positronium forms at temperatures around $50-80$ keV. If formation and equilibration were instantaneous, the resulting change in $N_{\mathrm{eff}}^{\mathrm{SM}}$ would be at most $|\Delta N_{\mathrm{eff}}| \sim 10^{-4}$, comparable to other uncertainties in the current benchmark value for $N_{\mathrm{eff}}^{\mathrm{SM}}$. A more gradual formation could however yield a larger change, necessitating in turn a more detailed investigation before we can conclusively neglect the effect of positronium formation on $N_{\mathrm{eff}}^{\mathrm{SM}}$.

Within the context of a Chern-Simons running-vacuum-model (RVM) cosmology, one expects an early-matter dominated (eMD) reheating period after RVM inflation driven by the axion field. Treating thus in this work Chern-Simons RVM cosmology as an effective $f(R)$ gravity theory characterized by logarithmic corrections of the spacetime curvature, we study the gravitational-wave (GW) signal induced by the nearly-scale invariant inflationary adiabatic curvature perturbations during the transition from the eMD era driven by the axion to the late radiation-dominated era. Remarkably, by accounting for the extra GW scalaron polarization present within $f(R)$ gravity theories, we find regions in the parameter space of the theory where one is met with a distinctive induced GW signal with a universal $f^6$ high-frequency scaling compared to the $f^7$ scaling present in general relativity (GR). Interestingly enough, for axion masses $m_a$ higher than 1 GeV and axion gauge couplings $f_a$ above $10^{-3}$ Planck mass, one can produce induced GW spectra within the sensitivity bands of future GW observatories such as the Einstein Telescope (ET), the Laser Interferometer Space Antenna (LISA), the Big Bang Observer (BBO) and the Square Kilometer Arrays (SKA).

We use Weyl connection and Weyl geometry in order to construct novel modified gravitational theories. In the simplest case where one uses only the Weyl-connection Ricci scalar as a Lagrangian, the theory recovers general relativity. However, by upgrading the Weyl field to a dynamical field with a general potential and/or general couplings constructed from its trace, leads to new modified gravity theories, where the extra degree of freedom is the Weyl field. Additionally, since the Weyl-connection Ricci scalar differs from the Levi-Civita Ricci scalar by terms up to first derivatives of the Weyl field, the resulting field equations for both the metric and the Weyl field are of second order, and thus the theory is free from Ostrogradsky ghosts. Finally, we construct the most general theory, namely the $f(\tilde{R},\cal{A})$ gravity, which is also ghost free and has $2+2$ degrees of freedom. Applying the above classes of theories at a cosmological framework we obtain an effective dark energy sector of geometrical origin. In the simplest class of theories we are able to obtain an effective cosmological constant, and thus we recover $\Lambda$CDM paradigm, nevertheless in more general cases we acquire a dynamical dark energy. These theories can reproduce the thermal history of the Universe, and the corresponding dark energy equation-of-state parameter presents a rich behavior.

\texttt{DiscoTEX} is a highly accurate numerical algorithm for computing numerical weak-form solutions to distributionally sourced partial differential equations (PDE)s. The aim of this second paper, succeeding \cite{da2024discotex}, is to present its extension up to twelve orders. This will be demonstrated by computing numerical weak-form solutions to the distributionally sourced wave equation and comparing it to its exact solutions. The full details of the numerical scheme at higher orders will be presented.