Papers for Wednesday, Nov 22 2023

The statistical distribution and evolution of key properties (e.g. accretion rate, mass, or spin) of active galactic nuclei (AGN), remain an open debate in astrophysics. The ESA Euclid space mission, launched on July 1st 2023, promises a breakthrough in this field. We create detailed mock catalogues of AGN spectra, from the rest-frame near-infrared down to the ultraviolet, including emission lines, to simulate what Euclid will observe for both obscured (type 2) and unobscured (type 1) AGN. We concentrate on the red grisms of the NISP instrument, which will be used for the wide-field survey, opening a new window for spectroscopic AGN studies in the near-infrared. We quantify the efficiency in the redshift determination as well as in retrieving the emission line flux of the H$\alpha$+[NII] complex as Euclid is mainly focused on this emission line as it is expected to be the brightest one in the probed redshift range. Spectroscopic redshifts are measured for 83% of the simulated AGN in the interval where the H$\alpha$+[NII] is visible (0.89<z<1.83 at a line flux $>2x10^{-16}$ erg s$^{-1}$ cm$^{-2}$, encompassing the peak of AGN activity at $z\simeq 1-1.5$) within the spectral coverage of the red grism. Outside this redshift range, the measurement efficiency decreases significantly. Overall, a spectroscopic redshift is correctly determined for ~90% of type 2 AGN down to an emission line flux of $3x10^{-16}$ erg s$^{-1}$ cm$^{-2}$, and for type 1 AGN down to $8.5x10^{-16}$ erg s$^{-1}$ cm$^{-2}$. Recovered black hole mass values show a small offset with respect to the input values ~10%, but the agreement is good overall. With such a high spectroscopic coverage at z<2, we will be able to measure AGN demography, scaling relations, and clustering from the epoch of the peak of AGN activity down to the present-day Universe for hundreds of thousand AGN with homogeneous spectroscopic information.

Type Ia supernovae (SNe Ia) were instrumental in establishing the acceleration of the universe's expansion. By virtue of their combination of distance reach, precision, and prevalence, they continue to provide key cosmological constraints, complementing other cosmological probes. Individual SN surveys cover only over about a factor of two in redshift, so compilations of multiple SN datasets are strongly beneficial. We assemble an updated "Union" compilation of 2087 cosmologically useful SNe Ia from 24 datasets ("Union3"). We take care to put all SNe on the same distance scale and update the light-curve fitting with SALT3 to use the full rest-frame optical. Over the next few years, the number of cosmologically useful SNe Ia will increase by more than a factor of ten, and keeping systematic uncertainties subdominant will be more challenging than ever. We discuss the importance of treating outliers, selection effects, light-curve shape and color populations and standardization relations, unexplained dispersion, and heterogeneous observations simultaneously. We present an updated Bayesian framework, called UNITY1.5 (Unified Nonlinear Inference for Type-Ia cosmologY), that incorporates significant improvements in our ability to model selection effects, standardization, and systematic uncertainties compared to earlier analyses. As an analysis byproduct, we also recover the posterior of the SN-only peculiar-velocity field, although we do not interpret it in this work. We compute updated cosmological constraints with Union3 and UNITY1.5, finding weak 1.7--2.6sigma tension with LambdaCDM and possible evidence for thawing dark energy. We release our binned SN distances to the community.

Odd radio circles (ORCs) are mysterious rings of faint, diffuse emission recently discovered in radio surveys. Some are potentially associated with galaxies, and proposed to be synchrotron emission from remnants of galactic outflows, which we call OGREs. Assuming that ORCs arise from OGREs, we discuss the broadband non-thermal emission and their evolution. We posit that a large amount of energy was ejected from the central galaxy in the past, creating an outgoing shock where cosmic rays are accelerated. From the observed spectral index and size of the ORCs, we estimate the shock velocity and the injected energy. For reasonable values of the magnetic field and temperature of the ambient medium, we find that the ejected energy is required to be as high as ~10^60 erg to account for the observed radio power, suggesting that the energy source is active galactic nuclei. We also calculate the spectral energy distributions (SEDs) of the OGREs and their evolution, including synchrotron, inverse Compton (IC) and bremsstrahlung emission from electrons, and pion-decay emission from protons. Younger OGREs are expected to have SEDs with synchrotron and IC peaks in the soft X-ray and gamma-ray bands, respectively. In the future, they may be detectable at radio and higher frequencies, for example as ``odd X-ray circles''. In addition, infrared IC emission may be observable from some of the ORCs found so far. Future broadband observations of ORCs should provide not only critical tests of this model, but may also offer unique probes of feedback effects on circumgalactic scales.

The International Conference on Auditory Display (ICAD) is a significant event for researchers and practitioners interested in exploring the use of sound in conveying information and data. Since its inception in 1994, the conference has served as a vital forum for exchanging ideas and presenting research findings in the field of auditory display. While the conference primarily focuses on auditory display and sound design, astronomy has made its presence felt in the proceedings of the conference over the years. However, its not until the current ICAD conference where astronomy features a dedicated session. This paper aims to provide an statistical overview of the presence of astronomy in the ICAD conference's history from 1994 to 2022, highlighting some of the contributions made by researchers in this area, as well as the topics of interest that have captured the attention of sound artists.

We present a spatially-resolved excitation analysis for the central molecular zone (CMZ) of the starburst galaxy NGC 253 using the data from the ALMA Large program ALCHEMI, whereby we explore parameters distinguishing NGC 253 from the quiescent Milky Way's Galactic Center (GC). Non-LTE analyses employing a hierarchical Bayesian framework are applied to Band 3-7 transitions from nine molecular species to delineate the position-position-velocity distributions of column density ($N_\mathrm{H_2}$), volume density ($n_\mathrm{H_2}$), and temperature ($T_\mathrm{kin}$) at 27 pc resolution. Two distinct components are detected: a low-density component with $(n_\mathrm{H_2},\ T_\mathrm{kin})\sim(10^{3.3}\ \mathrm{cm}^{-3}, 85 K)$ and a high-density component with $(n_\mathrm{H_2},\ T_\mathrm{kin})\sim (10^{4.4}\ \mathrm{cm}^{-3}, 110\ \mathrm{K})$, separated at $n_\mathrm{H_2}\sim10^{3.8}\ \mathrm{cm}^{-3}$. NGC 253 has $\sim10$ times the high-density gas mass and $\sim3$ times the dense-gas mass fraction of the GC. These properties are consistent with their HCN/CO ratio but cannot alone explain the factor of $\sim30$ difference in their star formation efficiencies (SFEs), contradicting the dense-gas mass to star formation rate scaling law. The $n_\mathrm{H_2}$ histogram toward NGC 253 exhibits a shallow declining slope up to $n_\mathrm{H_2}\sim10^6\ \mathrm{cm}^{-3}$, while that of the GC steeply drops in $n_\mathrm{H_2}\gtrsim10^{4.5}\ \mathrm{cm}^{-3}$ and vanishes at $10^5\ \mathrm{cm}^{-3}$. Their dense-gas mass fraction ratio becomes consistent with their SFEs when the threshold $n_\mathrm{H_2}$ for the dense gas is taken at $\sim 10^{4.2\mbox{-}4.6}\ \mathrm{cm}^{-3}$. The rich abundance of gas above this density range in the NGC 253 CMZ, or its scarcity in the GC, is likely to be the critical difference characterizing the contrasting star formation in the centers of the two galaxies.

Dark matter haloes form from small perturbations to the almost homogeneous density field of the early universe. Although it is known how large these initial perturbations must be to form haloes, it is rather poorly understood how to predict which particles will end up belonging to which halo. However, it is this process that determines the Lagrangian shape of protohaloes and is therefore essential to understand their mass, spin and formation history. Here, we present a machine-learning framework to learn how the protohalo regions of different haloes emerge from the initial density field. This involves one neural network to distinguish semantically which particles become part of any halo and a second neural network that groups these particles by halo membership into different instances. This instance segmentation is done through the Weinberger method, in which the network maps particles into a pseudo-space representation where different instances can be distinguished easily through a simple clustering algorithm. Our model reliably predicts the masses and Lagrangian shapes of haloes object-by-object, as well as summary statistics like the halo-mass function. We find that our model extracts information close to optimal by comparing it to the degree of agreement between two N-body simulations with slight differences in their initial conditions. We publish our model open-source and suggest that it can be used to inform analytical methods of structure formation by studying the effect of systematic manipulations of the initial conditions.

Detecting stochastic gravitational wave backgrounds (SGWBs) with The Laser Interferometer Space Antenna (LISA) is among the mission science objectives. Disentangling SGWBs of astrophysical and cosmological origin is a challenging task, further complicated by the noise level uncertainties. In this study, we introduce a Bayesian methodology to infer upon SGWBs, taking inspiration from Gaussian stochastic processes. We investigate the suitability of the approach for signal of unknown spectral shape. We do by discretely exploring the model hyperparameters, a first step towards a more efficient transdimensional exploration. We apply the proposed method to a representative astrophysical scenario: the inference on the astrophysical foreground of Extreme Mass Ratio Inspirals, recently estimated in~\cite{Pozzoli2023}. We find the algorithm to be capable of recovering the injected signal even with large priors, while simultaneously providing estimate of the noise level.

Radio galaxies dominate the radio sky and are essential to the galaxy evolution puzzle. High-resolution studies of statistical samples of radio galaxies are expected to shed light on the triggering mechanisms of the AGN, alternating between the phases of activity and quiescence. In this work, we focus on the sub-arcsec radio structures in the central regions of the 35 radio galaxies over 6.6 $deg^2$ of the Lockman Hole region. These sources were previously classified as active, remnant, and candidate restarted radio galaxies using 150 MHz LOFAR observations. We examine the morphologies and study the spectral properties of their central regions to explore their evolutionary stages and revise the criteria used to select the initial sample. We use the newly available LOFAR 150 MHz image obtained using international baselines, achieving 0.38'' x 0.30'' resolution, making this the first systematic study of the nuclear regions at high resolution and low frequency. We use publicly available images from the FIRST survey at 1.4 GHz and the Karl G. Jansky VLA Sky Survey at 3 GHz to achieve our goals. In addition, for one restarted candidate we present new dedicated observations with the VLA at 3 GHz. We have found various morphologies of the central regions of the radio galaxies in our sample, some resembling miniature double-double radio galaxies. We also see the beginnings of active jets or distinct detections unrelated to the large-scale structure. Furthermore, we have found diverse radio spectra in our sample - flat, steep, or peaked between 150 MHz and 3 GHz, indicative of the different life-cycle phases. Based on these analyses, we confirm five of six previously considered restarted candidates and identify three more from the active sample, supporting previous results suggesting that the restarted phase can occur after a relatively short remnant phase (i.e. a few tens of millions of years).

Black holes with masses between 100 to 100,000 times the mass of the Sun are classified as intermediate-mass black holes, the possible missing link between stellar-mass and supermassive black holes. Stellar-mass black holes are endpoints of the evolution of stars initially more massive than roughly 20 $\rm{M}_{\odot}$ and generally weigh about 10 to 100 $\rm{M}_{\odot}$. Supermassive black holes are found in the centre of many galaxies and weigh between $10^{6}$ to $10^{10} \ \rm{M}_{\odot}$. The origin of supermassive black holes remains an unresolved problem in astrophysics, with many viable pathways suggesting that they undergo an intermediate-mass phase. Whether intermediate-mass black holes really stand as an independent category of black holes or rather they represent the heaviest stellar mass and the lightest supermassive black holes is still unclear, mostly owing to the lack of an observational smoking gun. The first part of this chapter summarises proposed formation channels of intermediate-mass black holes by focusing on their formation and growth in dense stellar environments like globular and nuclear star clusters. Also, it highlights how the growth of intermediate-mass black holes through mergers with other black holes is important from the point of view of gravitational waves and seeding of supermassive black holes in our Universe. The second part of the chapter focuses on the multi-wavelength observational constraints on intermediate-mass black holes in dense star clusters and dwarf galactic nuclei and the possible aid that future GW detectors can bring to unravel the mystery of intermediate-mass black holes.

We present a suite of models of the coherent magnetic field of the Galaxy (GMF) based on new divergence-free parametric functions describing the global structure of the field. The model parameters are fit to the latest full-sky Faraday rotation measures of extragalactic sources (RMs) and polarized synchrotron intensity maps from WMAP and Planck (PI), employing multiple models for the density of thermal and cosmic-ray electrons in the Galaxy. The robustness of the inferred properties of the GMF is gauged by studying many combinations of parametric field models and electron density models. We determine the pitch angle of the local magnetic field (11+/-1 deg.), explore the evidence for a grand-design spiral coherent magnetic field (inconclusive), determine the strength of the toroidal magnetic halo below and above the disk (same within 10%), set constraints on the half-height of the cosmic-ray diffusion volume (> 2.9 kpc), investigate the compatibility of RM- and PI-derived magnetic field strengths (compatible under certain assumptions) and check if the toroidal halo field could be created by the shear of the poloidal halo due to the differential rotation of the Galaxy (possibly). A set of eight models is identified to broadly encompass the present uncertainties in the coherent GMF -- spanning different functional forms, data products and auxiliary input, and maximizing the differences in their predictions. We present the corresponding skymaps of rates for axion-photon conversion in the Galaxy, and deflections of ultra-high energy cosmic rays. Based on comparing the predicted deflections of UHECRs traversing the Galaxy in these models, we conclude that the deflection uncertainties are smaller than the deflections themselves for most of the sky and that the rigidity threshold for nuclear astronomy can be lowered by a factor of two if GMF deflections are taken into account.

Stellar mergers lead to diverse phenomena: rejuvenated blue stragglers, magnetised and peculiar stars, transients and nebulae. Using a grid of about 6000 detailed 1D binary evolution models (initial component masses of 0.5-20$\,\text{M}_{\odot}$ at solar metallicity), we investigate which initial binary-star configurations lead to contact and classical common-envelope (CE) phases and assess the likelihood of a subsequent merger. Considering rotation and tides, we identify five mechanisms leading to contact and mergers: runaway mass transfer, $\text{L}_{2}$-overflow, accretor expansion, tidally-driven orbital decay, and non-conservative mass transfer. At least 40% of mass-transferring binaries with initial primary masses of 5-20$\,\text{M}_{\odot}$ enter contact, with >12% and >19% likely merging and evolving into a classical CE phase, respectively. Classical CE evolution occurs in late Case-B and Case-C binaries for initial mass ratios $q_{\text{i}}$ < 0.15-0.35, stable mass transfer for larger $q_{\text{i}}$. Early Case-B binaries enter contact for $q_{\text{i}}$ < 0.15-0.35 and in initially wider Case-A binaries, this occurs for $q_{\text{i}}$ < 0.35. All initially closest Case-A systems form contact binaries. We predict that binaries entering contact with $q$ < 0.5 merge or detach on a thermal timescale, while those formed with $q$ > 0.5 lead to long-lived contact phases. The fact that contact binaries are almost exclusively observed with $q$ > 0.5 confirms our expectations. Our contact, merger and classical CE incidences are lower limits because the mass transfer in our models is non-conservative. In most binaries, the non-accreted mass cannot be ejected and may settle in disks or lead to contact phases and mergers. Overall, contact binaries are a frequent and fascinating result of binary mass transfer of which the exact outcomes still remain to be understood and explored further.

We present full Stokes MeerKAT L band (856--1712\,MHz) observations of \chg{36} high latitude supernova remnants. Sensitive, high dynamic range images show a wealth of structure. G15.1$-$1.6 appears to be an HII region rather than an SNR. G30.7$-$2.0 consists of three background extragalactic sources which appear to form an arc when imaged with much lower resolution. At least half of the remnants in the sample contain ``blowouts'', or ``ears'' showing these to be a common feature. Analysis of the polarimetric data reveals details of the magnetic field structure in the emitting regions of the remnants as well as magnetized thermal plasma in front of polarized emission. The chance alignment of G327.6+14.6 with a background AGN with very extended polarized jets allows testing for the presence of Faraday effects in the interior of the remnant. Scant evidence of Faraday rotating material is found in the interior of this remnant.

In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cram\'er-Rao absolute lower bound (CRLB) as well as the performance bounds for high-dimensional implicit estimators from a generalized Taylor expansion. This later approach allows us to obtain computable prescriptions for the bias and variance of the joint estimators. We compare these prescriptions with empirical results from numerical simulations in the case of the weighted least squares estimator (introducing an improved version, denoted stochastic weighted least-squares) as well as with the maximum likelihood estimator, finding excellent agreement. We demonstrate that these estimators provide quasi-unbiased joint estimations of the flux and background, with a variance that approaches the CRLB very tightly and are, hence, optimal, unlike the case of sequential estimation used commonly in astronomical photometry which is sub-optimal. We compare our predictions with numerical simulations of realistic observations, as well as with observations of a bona-fide non-variable stellar source observed with TESS, and compare it to the results from the sequential estimation of background and flux, confirming our theoretical expectations. Our practical estimators can be used as benchmarks for general photometric pipelines, or for applications that require maximum precision and accuracy in absolute photometry.

Astrometry is one of the main pillars of astronomy, and one of its oldest branches. Over the years, an increasing number of astrometric works by means of Hubble Space Telescope (HST) data have revolutionized our understanding of various phenomena. With the launch of JWST, it becomes almost instinctive to want to replicate or improve these results with data taken with the newest, state-of-the-art, space-based telescope. In this regard, the initial focus of the community has been on the Near-Infrared (NIR) detectors on board of JWST because of their high spatial resolution. This paper begins the effort to capture and apply what has been learned from HST to the Mid-InfraRed Instrument (MIRI) of JWST by developing the tools to obtain high-precision astrometry and photometry with its imager. We describe in detail how to create accurate effective point-spread-function (ePSF) models and geometric-distortion corrections, analyze their temporal stability, and test their quality to the extent of what is currently possible with the available data in the JWST MAST archive. We show that careful data reduction provides deep insight on the performance and intricacies of the MIRI imager, and of JWST in general. In an effort to help the community to devise new observing programs, we make our ePSF models and geometric-distortion corrections publicly available.

The waves generated by high-energy proton and alpha particles streaming from solar flares into regions of colder plasma are explored using particle-in-cell simulations. Initial distribution functions for the protons and alphas consist of two populations: an energetic, streaming population represented by an anisotropic ($T_{\parallel} > T_{\perp}$), one-sided kappa function and a cold, Maxwellian background population. The anisotropies and non-zero heat fluxes of these distributions destabilize oblique waves with a range of frequencies below the proton cyclotron frequency. These waves scatter particles out of the tails of the initial distributions along constant energy surfaces in the wave frame. Overlap of the nonlinear resonance widths allows particles to scatter into near isotropic distributions by the end of the simulations. The dynamics of $^3$He are explored using test particles. Their temperatures can increase by a factor of nearly 20. Propagation of such waves into regions above and below the flare site can lead to heating and transport of $^3$He into the flare acceleration region. The amount of heated $^3$He that will be driven into the flare site is proportional to the wave energy. Using values from our simulations, we show that the abundance of $^3$He driven into the acceleration region should approach that of $^4$He in the corona. Therefore, waves driven by energetic ions produced in flares are a strong candidate to drive the enhancements of $^3$He observed in impulsive flares.

Given the inexorable increase in the Sun's luminosity, Earth will exit the habitable zone in ~1 Gyr. There is a negligible chance that Earth's orbit will change during that time through internal Solar System dynamics. However, there is a ~1% chance per Gyr that a star will pass within 100 au of the Sun. Here, we use N-body simulations to evaluate the possible evolutionary pathways of the planets under the perturbation from a close stellar passage. We find a ~92% chance that all eight planets will survive on orbits similar to their current ones if a star passes within 100 au of the Sun. Yet a passing star may disrupt the Solar System, by directly perturbing the planets' orbits or by triggering a dynamical instability. Mercury is the most fragile, with a destruction rate (usually via collision with the Sun) higher than that of the four giant planets combined. The most probable destructive pathways for Earth are to undergo a giant impact (with the Moon or Venus) or to collide with the Sun. Each planet may find itself on a very different orbit than its present-day one, in some cases with high eccentricities or inclinations. There is a small chance that Earth could end up on a more distant (colder) orbit, through re-shuffling of the system's orbital architecture, ejection into interstellar space (or into the Oort cloud), or capture by the passing star. We quantify plausible outcomes for the post-flyby Solar System.

Mrk 783 is a narrow-line Seyfert 1 galaxy that possesses a relatively large two-sided radio emission extending up to 14 kpc from the active nucleus possibly connected with a large-scale ionized gas emission. We obtained a deep [OIII] image that revealed an extended system of emission knots and diffuse ionized gas surrounding the main galaxy. The high-excited gas is related not only with the radio structure, but also with tidal features illuminated by the active nucleus radiation up to the projected distance 41 kpc as it follows from the emission lines intensities and kinematics derived from the long-slit spectroscopic data. Moreover the part of the disk of the companion galaxy SDSS J130257.20+162537.1 located at 99 kpc projected distances to the north of Mrk 783 also falls in the AGN ionizing cone. It is possible that Mrk 783 can be considered as `Hanny's Voorwerp precursor', i.e. a galaxy that demonstrates signs of sequential switching from radio-loud to radio-quiet nuclear activity, in the moment before falling of its ionization luminosity.

It has been suggested that $\beta$ Pic b has a supersolar metallicity and subsolar C/O ratio. Assuming solar carbon and oxygen abundances for the star $\beta$ Pic and therefore the planet's parent protoplanetary disk, $\beta$ Pic b's C/O ratio suggests that it formed via core accretion between its parent protoplanteary disk's H$_{2}$O and CO$_{2}$ ice lines. $\beta$ Pic b's high metallicity is difficult to reconcile with its mass $M_{\text{p}}~=~11.7~M_{\text{Jup}}$ though. Massive stars can present peculiar photospheric abundances that are unlikely to record the abundances of their former protoplanetary disks. This issue can be overcome for early-type stars in moving groups by infering the elemental abundances of the FGK stars in the same moving group that formed in the same molecular cloud and presumably share the same composition. We infer the photospheric abundances of the F dwarf HD 181327, a $\beta$ Pic moving group member that is the best available proxy for the composition of $\beta$ Pic b's parent protoplanetary disk. In parallel, we infer updated atmospheric abundances for $\beta$ Pic b. As expected for a planet of its mass formed via core-accretion beyond its parent protoplanetary disk's H$_{2}$O ice line, we find that $\beta$ Pic b's atmosphere is consistent with stellar metallicity and confirm that is has superstellar carbon and oxygen abundances with a substellar C/O ratio. We propose that the elemental abundances of FGK dwarfs in moving groups can be used as proxies for the otherwise difficult-to-infer elemental abundances of early-type and late-type members of the same moving groups.

We present a new sample of 158 galaxies at redshift $z>7.5$ selected from deep JWST NIRCam imaging of five widely-separated sightlines in the CANUCS survey. Two-thirds of the pointings and 80% of the galaxies are covered by 12 to 14 NIRCam filters, including seven to nine medium bands, providing accurate photometric redshifts and robustness against low redshift interlopers. A sample of 28 galaxies at $z>7.5$ with spectroscopic redshifts shows a low systematic offset and scatter in the difference between photometric and spectroscopic redshifts. We derive the galaxy UV luminosity function at redshifts 8 to 12, finding a slightly higher normalization than previously seen with HST at redshifts 8 to 10. We observe a steeper decline in the galaxy space density from $z=8$ to $12$ than found by most JWST Cycle 1 studies. In particular, we find only eight galaxies at $z>10$ and none at $z>12.5$, with no $z>10$ galaxies brighter than F277W AB=28 or $M_{UV}=-20$ in our unmasked, delensed survey area of 53.4 square arcminutes. We attribute the lack of bright $z>10$ galaxies in CANUCS compared to GLASS and CEERS to intrinsic variance in the galaxy density along different sightlines. The evolution in the CANUCS luminosity function between $z=8$ and $12$ is comparable to that predicted by simulations that assume a standard star formation efficiency, without invoking any special adjustments.

We have recently presented observational evidence which suggests that the origin of the second generation (G2) stars in globular clusters (GCs) is due to the binary-mediated collision of primordial (G1) low-mass main-sequence (MS) stars. This mechanism avoids both the mass budget problem and the need of external gas for dilution. Here, we report on another piece of evidence supporting this scenario: (1) the fraction of MS binaries is proportional to the fraction of G1 stars in GCs and, at the same time, (2) the smaller the fraction of G1 stars is, the more deficient binaries of higher mass ratio (q$>0.7$) are. They are, on average, harder than their smaller mass-ratio counterparts due to higher binding energy at a given primary mass. Then (2) implies that (1) is due to the merging\slash collisions of hard binaries rather than to their disruption. These new results complemented by the present-day data on binaries lead to the following conclusions: (i) the mass-ratio distribution of binaries, particularly short-period ones, with low-mass primaries, $M_{\rm P} < 1.5$ M$_{\sun}$, is strongly peaked close to q$=1.0$, whereas (ii) dynamical processes at high stellar density tend to destroy softer binaries and make hard (nearly) twin binaries to become even harder and favor their mergers and collisions. G2 stars formed this way gain mass that virtually doubles the primary one, $2M_{\rm P}$, at which the number of G1 stars is $\sim5$ times smaller than at $M_{\rm P}$ according to the slope of a Milky Way-like IMF at $M_{\rm MS} < 1.0$ M$_{\sun}$.

One of the main objectives of the Mars Exploration Program is to search for evidence of past or current life on the planet. To achieve this, Mars exploration has been focusing on regions that may have liquid or frozen water. A set of critical areas may have seen cycles of ice thawing in the relatively recent past in response to periodic changes in the obliquity of Mars. In this work, we use convolutional neural networks to detect surface regions containing "Brain Coral" terrain, a landform on Mars whose similarity in morphology and scale to sorted stone circles on Earth suggests that it may have formed as a consequence of freeze/thaw cycles. We use large images (~100-1000 megapixels) from the Mars Reconnaissance Orbiter to search for these landforms at resolutions close to a few tens of centimeters per pixel (~25--50 cm). Over 52,000 images (~28 TB) were searched (~5% of the Martian surface) where we found detections in over 200 images. To expedite the processing we leverage a classifier network (prior to segmentation) in the Fourier domain that can take advantage of JPEG compression by leveraging blocks of coefficients from a discrete cosine transform in lieu of decoding the entire image at the full spatial resolution. The hybrid pipeline approach maintains ~93% accuracy while cutting down on ~95% of the total processing time compared to running the segmentation network at the full resolution on every image. The timely processing of big data sets helps inform mission operations, geologic surveys to prioritize candidate landing sites, avoid hazardous areas, or map the spatial extent of certain terrain. The segmentation masks and source code are available on Github for the community to explore and build upon.

The atmospheres of small, close-in exoplanets are vulnerable to rapid mass-loss during protoplanetary disc dispersal via a process referred to as `boil-off', in which confining pressure from the local gas disc reduces, inducing atmospheric loss and contraction. We construct self-consistent models of planet evolution during gaseous core accretion and boil-off. As the surrounding disc gas dissipates, we find that planets lose mass via subsonic breeze outflows which allow causal contact to exist between disc and planet. Planets initially accrete of order $\sim 10\%$ in atmospheric mass, however, boil-off can remove $\gtrsim 90\%$ of this mass during disc dispersal. We show that a planet's final atmospheric mass fraction is strongly dictated by the ratio of cooling timescale to disc dispersal timescale, as well as the planet's core mass and equilibrium temperature. With contributions from core cooling and radioactivity, we show that core luminosity eventually leads to the transition from boil-off to core-powered mass-loss. We find that smaller mass planets closest to their host star may have their atmospheres completely stripped through a combination of boil-off and core-powered mass-loss during disc dispersal, implying the existence of a population-level radius gap emerging as the disc disperses. We additionally consider the transition from boil-off/core-powered mass-loss to X-ray/EUV (XUV) photoevaporation by considering the penetration of stellar XUV photons below the planet's sonic surface. Finally, we show that planets may open gaps in their protoplanetary discs during the late stages of boil-off, which may enhance mass-loss rates.

An epoch of matter domination in the early universe can enhance the primordial stochastic gravitational wave signal, potentially making it detectable to upcoming gravitational wave experiments. However, the resulting gravitational wave signal is quite sensitive to the end of the early matter-dominated epoch. If matter domination ends gradually, a cancellation results in an extremely suppressed signal, while in the limit of an instantaneous transition, there is a resonant-like enhancement. The end of the matter dominated epoch cannot be instantaneous, however, and previous analyses have used a Gaussian smoothing technique to account for this, and consider only a limited regime around the fast transition limit. In this work, we present a study of the enhanced gravitational wave signal from early matter domination without making either approximation and show how the signal smoothly evolves from the strongly suppressed to strongly enhanced regimes.

Active galactic nuclei (AGN) play an integral role in galaxy formation and evolution by influencing galaxies and their environments through radio jet feedback. Historically, interpreting observations of radio galaxies and quantifying radio jet feedback has been challenging due to degeneracies between their physical parameters. In particular, it is well-established that different combinations of jet kinetic power and environment density can yield indistinguishable radio continuum properties, including apparent size and Stokes I luminosity. We present an approach to breaking this degeneracy by probing the line-of-sight environment with Faraday rotation. We study this effect in simulations of three-dimensional relativistic magnetohydrodynamic AGN jets in idealised environments with turbulent magnetic fields. We generate synthetic Stokes I emission and Faraday rotation measure (RM) maps, which enable us to distinguish between our simulated sources. We find enhanced RMs near the jet head and lobe edges and an RM reversal across the jet axis. We show that increasing the environment density and the average cluster magnetic field strength broadens the distribution of Faraday rotation measure values. We study the depolarisation properties of our sources, finding that the hotspot regions depolarise at lower frequencies than the lobes. We quantify the effect of depolarisation on the RM distribution, finding that the frequency at which the source is too depolarised to measure the RM distribution accurately is a probe of environmental properties. This technique offers a range of new opportunities for upcoming surveys, including probing radio galaxy environments and determining more accurate estimates of the AGN feedback budget.

The Australian SKA Pathfinder (ASKAP) has surveyed the sky at multiple frequencies as part of the Rapid ASKAP Continuum Survey (RACS). The first two RACS observing epochs, at 887.5 (RACS-low) and 1367.5 (RACS-mid) MHz, have been released (McConnell et al., 2020; Duchesne et al., 2023). A catalogue of radio sources from RACS-low has also been released, covering the sky south of declination +30$^\circ$ (Hale et al., 2021). With this paper, we describe and release the first set of catalogues from RACS-mid, covering the sky below declination +49$^\circ$. The catalogues are created in a similar manner to the RACS-low catalogue, and we discuss this process and highlight additional changes. The general purpose primary catalogue covering 36 200 deg$^2$ features a variable angular resolution to maximise sensitivity and sky coverage across the catalogued area, with a median angular resolution of 11.2" times 9.3". The primary catalogue comprises 3 105 668 radio sources, including those in the Galactic Plane (2 861 923 excluding Galactic latitudes of $|b|<5^\circ$) and we estimate the catalogue to be 95% complete for sources above 1.6 mJy. With the primary catalogue, we also provide two auxiliary catalogues. The first is a fixed-resolution, 25-arcsec catalogue approximately matching the sky coverage of the RACS-low catalogue. This 25-arcsec catalogue is constructed identically to the primary catalogue, except images are convolved to a less-sensitive 25-arcsec angular resolution. The second auxiliary catalogue is designed for time-domain science, and is the concatenation of source-lists from the original RACS-mid images with no additional convolution, mosaicking, or de-duplication of source entries to avoid losing time-variable signals. All three RACS-mid catalogues, and all RACS data products, are available through the CSIRO ASKAP Science Data Archive (CASDA).

This article revisits Granda-Oliveros holographic dark energy (GOHDE) model, explores the features of the parameter space and shows that its ability to explain the late-time acceleration is only due to the integration constant that appears by construction. We show that the GOHDE behaves like the dominant energy component and naturally behaves like dark energy in the late phase. In the matter-dominated period, it acts like pressureless matter and exhibits radiation-like behaviour in the very early stages. Adjusting the free parameters could subdue or enhance these characteristics. Depending on the parameters, GOHDE can act similarly to concordance, phantom or quintessence-like dark energies with singular equation of states. From the point of local observations, we show that the GOHDE model is observationally indistinguishable from $w$CDM and encompasses $\Lambda$CDM as a specific case. Our analysis reveals that while a departure from $\Lambda$CDM could account for late-time acceleration, it falls short of a consistent description of the entire cosmic history. Furthermore, we utilize various datasets, including OHD, Pantheon, CMB Shift parameter, BAO, and QSO, to constrain the free parameters of the GOHDE model. Our analysis indicates that the best fit, assuming the GO cut-off, aligns with the $\Lambda$CDM model. Additionally, we use statistical quantifiers such as AIC, BIC, and $\chi^2$ to test the model's goodness with various data combinations and estimate the Bayes factor to contrast the models. Our study suggests that the standard GOHDE model is equally likely as the $\Lambda$CDM model, ultimately favouring the latter, with $\beta=0.686^{+0.048}_{-0.044}$ and $w{z_0}=-0.988^{+0.042}_{-0.044}$. Given the current observations, we conclude that, for a flat universe, the $\Lambda$CDM case is statistically the best and probably the only consistent solution from the GOHDE construction.

The Hairy Kerr black hole is a novel black hole solution that depicts a rotating space-time encompassed by an axisymmetric fluid. It has significant observational importance and is an excellent candidate for an astrophysical black hole. Our study investigates the impact of the hairy charge on the quasi-periodic oscillations (QPOs) of X-ray binaries in the Hairy Kerr black hole (HKBH) space-time. The relativistic precession model is employed to compute the three principal frequencies of the accretion disk encircling the HKBH. We compare our outcomes with the observations of five X-ray binaries and employ a Markov chain Monte Carlo (MCMC) simulation for restricting the hairy charge parameters. There is no substantial evidence for the existence of hairy charge in the HKBH space-time. Therefore, we are placing observational constraints on the deformation parameters with $0<\alpha<0.07697$ and hairy charge values ranging from $0.27182<l_0/M<2.0$.

Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as the Sun, exhibit RV jitter on the order of a few m/s due to active regions on their surfaces. Time series of chromospheric activity indicators, such as the Ca II H&K lines, can be utilized to reduce the impact of such activity phenomena on exoplanet search programs. In addition, the identification and correction of instrumental effects can improve the precision of RV exoplanet surveys. We aim to update the HARPS-RVBank RV database, previously published by Trifonov et al. (2020), and include additional 3.5 years of time series and Ca II H&K lines ($R'_{HK}$) chromospheric activity indicators. This additional data will aid in the analysis of the impact of stellar magnetic activity on the RV time series obtained with the HARPS instrument. Our updated database aims to provide a valuable resource for the exoplanet community in understanding and mitigating the effects of such stellar magnetic activity on RV measurements. The new HARPS-RVBank database includes all stellar spectra obtained with the HARPS instrument prior to January 2022. The RVs corrected for small but significant nightly zero-point variations were calculated using the same method described in Trifonov et al. (2020). The $R'_{HK}$ estimates were determined from both individual spectra and co-added template spectra using the methodology outlined in Perdelwitz et al. (2021), which utilizes synthetic model spectra. The new version of the HARPS RV database has a total of 252615 RVs of 5239 stars. Of these, 200774 have $R'_{HK}$ values, which corresponds to 80% of all publicly available HARPS spectra. Currently, this is the largest public database of high-precision RVs, and the largest compilation of $R'_{HK}$ measurements.

[Abridged] The inner few AU of disks around young stars are best probed in the infrared. The James Webb Space Telescope (JWST) is now starting to characterize the chemistry of these regions in unprecedented detail. One peculiar subset of sources are the so-called ``CO2-only sources'', in which only a strong 15 $\mu$m CO2 feature was detected in the spectrum. One scenario that could explain the weak emission from H2O is the presence of a small, inner cavity in the disk. If this cavity were to extend past the H2O snowline, but not past the CO2 snowline, this could strongly suppress the H2O line flux w.r.t. that of CO2. In this work, we aim to test the validity of this statement. Using the thermo-chemical code Dust And LInes (DALI), we created a grid of T Tauri disk models with an inner cavity, meaning we fully depleted the inner region of the disk in gas and dust starting from the dust sublimation radius and ranging until a certain cavity radius. We present the evolution of the CO2 and H2O spectra of a disk with inner cavity size, showing that, when a large-enough cavity is introduced, a spectrum that was initially dominated by H2O lines can become CO2-dominated instead. However, the cavity size needed for this is around 4-5 AU, exceeding the nominal position of the CO2 snowline in a full disk. The cause of this is most likely the alteration of the thermal structure by the cavity, which pushes the snowlines outward. Alternative explanations for bright CO2 emission are also briefly discussed. Our modeling work shows that it is possible for the presence of a small inner cavity to explain strong CO2 emission in a spectrum. However, the cavity needed to do so is larger than what was initially expected. As such, this scenario will be easier to test with sufficiently high angular resolution (millimeter) observations.

WASP-107b is a warm ($\sim$740 K) transiting planet with a Neptune-like mass of $\sim$30.5 $M_{\oplus}$ and Jupiter-like radius of $\sim$0.94 $R_{\rm J}$, whose extended atmosphere is eroding. Previous observations showed evidence for water vapour and a thick high-altitude condensate layer in WASP-107b's atmosphere. Recently, photochemically produced sulphur dioxide (SO$_2$) was detected in the atmosphere of a hot ($\sim$1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 $\mu$m, but for temperatures below $\sim$1,000 K sulphur is predicted to preferably form sulphur allotropes instead of SO$_2$. Here we report the 9$\sigma$-detection of two fundamental vibration bands of SO$_2$, at 7.35 $\mu$m and 8.69 $\mu$m, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of the JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from $\sim$1,200 K down to $\sim$740 K. Additionally, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured ($\sim$7$\sigma$) over simpler cloud setups. Furthermore, water is detected ($\sim$12$\sigma$), but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity.

In this chapter we give an overview of the properties of X-ray binary systems containing a weakly magnetized neutron star. These are old (Giga-years life-time) semi-detached binary systems containing a neutron star with a relatively weak magnetic field (less than $\sim 10^{10}$ Gauss) and a low-mass (less than $1 M_\odot$) companion star orbiting around the common center of mass in a tight system, with orbital period usually less than 1 day. The companion star usually fills its Roche lobe and transfers mass to the neutron star through an accretion disk, where most of the initial potential energy of the in-falling matter is released, reaching temperatures of tens of million Kelvin degrees, and therefore emitting most of the energy in the X-ray band. Their emission is characterized by a fast-time variability, possibly related to the short timescales in the innermost part of the system. Because of the weak magnetic field, the accretion flow can approach the neutron star until it is accreted onto its surface sometimes producing spectacular explosions known as type-I X-ray bursts. In some sources, the weak magnetic field of the neutron star ($\sim 10^8-10^9$ Gauss) is strong enough to channel the accretion flow onto the polar caps, modulating the X-ray emission and revealing the fast rotation of the neutron star at millisecond periods. These systems are important for studies of fundamental physics, and in particular for test of Relativity and alternative theories of Gravity and for studies of the equation of state of ultra-dense matter, which are among the most important goals of modern physics and astrophysics.

The IRDC G14.225-0.506 is associated with a network of filaments, which result in two different dense hubs, as well as with several signposts of star formation activity. The aim of this work is to study the cm continuum emission to characterize the stellar population in G14.2. We performed deep (~1.5-3 microJy) radio continuum observations at 6 and 3.6 cm using the VLA in the A configuration (~0.3''). We have also made use of observations taken during different days to study the presence of variability at short timescales. We detected a total of 66 sources, 32 in the northern region G14.2-N and 34 in the southern region G14.2-S. Ten of the sources are found to be variable. Based on their spectral index, the emission in G14.2-N is mainly dominated by non-thermal sources while G14.2-S contains more thermal emitters. Approximately 75% of the sources present a counterpart at other wavelengths. In the inner 0.4~pc region around the center of each hub, the number of IR sources in G14.2-N is larger than in G14.2-S by a factor of 4. We also studied the relation between the radio luminosity and the bolometric luminosity, finding that the thermal emission of the studied sources is compatible with thermal radio jets. For our sources with X-ray counterparts, the non-thermal emitters follow a G\"udel-Benz relation with k = 0.03. We found similar levels of fragmentation between G14.2-N and G14.2-S, suggesting that both regions are most likely twin hubs. The non-thermal emission found in the less evolved objects suggests that G14.2-N may be composed of more massive YSOs as well as being in a more advanced evolutionary stage, consistent with the filament-halo gradient in age and mass from previous works. Our results confirm a wider evolutionary sequence starting in G14.2-S as the youngest part, followed by G14.2-N, and ending with the most evolved region M17.

B[e] type stars are characterised by strong emission lines, photometric $\&$ spectroscopic variabilities and unsteady mass-loss rates. MWC 137 is a galactic B[e] type star situated in the constellation Orion. Recent photometric observation of MWC 137 by TESS has revealed variabilities with a dominant period of 1.9 d. The origin of this variability is not known but suspected to be from stellar pulsation. To understand the nature and origin of this variability, we have constructed three different set of models of MWC 137 and performed non-adiabatic linear stability analysis. Several low order modes are found to be unstable in which models having mass in the range of 31 to 34 M$_{\odot}$ and 43 to 46 M$_{\odot}$ have period close to 1.9 d. The evolution of instabilities in the non-linear regime for model having solar chemical composition and mass of 45 M$_{\odot}$ leads to finite amplitude pulsation with a period of 1.9 d. Therefore in the present study we confirm that this variability in MWC 137 is due to pulsation. Evolutionary tracks passing through the location of MWC 137 in the HR diagram indicate that the star is either in post main sequence evolutionary phase or about to enter in this evolutionary phase.

Outflows are believed to be ubiquitous in all AGNs, although their presence in low luminosity AGNs, in particular, for LINERs, has only started to be explored. Their properties (geometry, mass and energetics) are still far from being properly characterised. We use integral field spectroscopic data from the MEGARA instrument, at GTC, to analyse a small sample of nine LINERs, candidates of hosting ionised gas outflows. We aim to study the main emission lines in the optical to identify their properties and physical origin. We obtained data cubes at the lowest (R$\sim$6000) and highest (R$\sim$20000) spectral resolution of MEGARA. We modelled and subtracted the stellar continuum to obtain the ionised gas contribution, and then fitted the emission lines to extract their kinematics (velocity and velocity dispersion). We identified outflows as a secondary component in the emission lines. The primary component of the emission lines was typically associated to gas in the galactic disc. For some objects, there is an enhanced-$\sigma$ region co-spatial with the secondary component. We associated it to turbulent gas produced due to the interaction with the outflows. We find signatures of outflows in six LINERs, with mass outflow rates ranging from 0.004 to 0.4 M$_{sun}$yr$^{-1}$ and energy rates from $\sim$10$^{38}$ to $\sim$10$^{40}$ erg s$^{-1}$. Their mean electronic density is 600cm$^{-3}$, extending to distances of $\sim$400 pc at an (absolute) velocity of $\sim$340 km s$^{-1}$ (on average). They tend to be compact and unresolved, although for some sources they are extended with a bubble-like morphology. Our results confirm the existence of outflows in the best LINER candidates identified using previous long-slit spectroscopic and imaging data. These outflows do not follow the scaling relations obtained for more luminous AGNs. For some objects we discuss jets as the main drivers of the outflows

We study the magnetic helicity evolution in neutron stars (NSs). First, we analyze how the surface terms affect the conservation law for the sum of the chiral imbalance of the charged particle densities and the density of the magnetic helicity. Our results are applied to a system with a finite volume, which can be a magnetized NS. We show that the contribution of these surface terms can potentially lead to the reconnection of magnetic field lines followed by X-ray or gamma bursts observed in magnetars. Comparing the new quantum surface term with the classical contribution known in the standard magnetic hydrodynamics, we obtain that its contribution dominates over the classical term only for NS with a rigid rotation. Second, we study the dynamics of chiral electrons which interact electroweakly with a background fermions having the velocity, arbitrarily depending on spatial coordinates, and the nonuniform density. We derive the the kinetic equations and the effective action for right and left particles. The correction to the Adler anomaly and to the anomalous electric current are obtained in the case of a rotating matter. Then, the obtained results are applied for the study of the magnetic helicity flow inside a magnetized rotating NS. We compute the characteristic time of the helicity change and demonstrate that it coincides with the the magnetic cycle period of certain pulsars.

In this paper, we present a full spatially resolved polarization map for the Vela Pulsar Wind Nebula (PWN) observed by IXPE. By employing effective background discrimination techniques, our results show a remarkably high degree of local polarization in the outskirt region, exceeding 60% (55%) with a probability of 95% (99%), which approaches the upper limit predicted by the synchrotron emission mechanism. The high degree of polarization suggests that the turbulent magnetic energy is at most 33% of the ordered one. In addition, the X-ray polarization map exhibits a toroidal magnetic field pattern that is consistent with the field revealed by radio observations across the entire nebula. This consistency reveals that the observed X-ray and radio emissions are radiated by electrons from the same magnetic field. Different from the Crab PWN, the consistency observed in the Vela PWN may be attributed to the interaction between the reverse shock of supernova blast wave and the PWN, which leads to a displacement between the synchrotron-cooled nebula and the fresh nebula close to the pulsar. These findings deepen our understanding of the structure and evolution of the Vela PWN, and the magnetohydrodynamic interaction in PWNe.

The LIGO, VIRGO and KAGRA Gravitational-wave (GW) observatories are getting ready for their fourth observational period, O4, scheduled to begin in March 2023, with improved sensitivities and thus higher event rates. GW-related computing has both large commonalities with HEP computing, particularly in the domain of offline data processing and analysis, and important differences, for example in the fact that the amount of raw data doesn't grow much with the instrument sensitivity, or the need to timely generate and distribute "event candidate alerts" to EM and neutrino observatories, thus making gravitational multi-messenger astronomy possible. Data from the interferometers are exchanged between collaborations both for low-latency and offline processing; in recent years, the three collaborations designed and built a common distributed computing infrastructure to prepare for a growing computing demand, and to reduce the maintenance burden of legacy custom-made tools, by increasingly adopting tools and architectures originally developed in the context of HEP computing. So, for example, HTCondor is used for workflow management, Rucio for many data management needs, CVMFS for code and data distribution, and more. We will present GW computing use cases and report about the architecture of the computing infrastructure as will be used during O4, as well as some planned upgrades for the subsequent observing run O5.

Minkowski functionals quantify the morphology of smooth random fields. They are widely used to probe statistical properties of cosmological fields. Analytic formulae for ensemble expectations of Minkowski functionals are well known for Gaussian and mildly non-Gaussian fields. In this paper we extend the formulae to composite fields which are sums of two fields and explicitly derive the expressions for the sum of uncorrelated mildly non-Gaussian and Gaussian fields. These formulae are applicable to observed data which is usually a sum of the true signal and one or more secondary fields that can be either noise, or some residual contaminating signal. Our formulae provide explicit quantification of the effect of the secondary field on the morphology and statistical nature of the true signal. As examples, we apply the formulae to determine how the presence of Gaussian noise can bias the morphological properties and statistical nature of Gaussian and non-Gaussian CMB temperature maps.

TOI-732 is an M dwarf hosting two transiting planets, which are located on the two opposite sides of the radius valley. By doubling the number of available space-based observations and increasing the number of radial velocity (RV) measurements, we aim at refining the parameters of TOI-732 b and c. We also aim at using the results to study the slope of both the radius valley and the density valley for a well characterised sample of M dwarf exoplanets. We performed a global MCMC analysis by jointly modelling ground-based light curves, CHEOPS and TESS observations, along with RV time series both taken from the literature and obtained with the MAROON-X spectrograph. The slopes of the M dwarf valleys were quantified via a Support Vector Machine (SVM) procedure. TOI-732 b is an ultra short period planet ($P\sim0.77$ d) with a radius $R_b=1.325_{-0.058}^{+0.057}$ $R_{\oplus}$ and a mass $M_b=2.46\pm0.19$ $M_{\oplus}$ (mean density $\rho_b=5.8_{-0.8}^{+1.0}$ g cm$^{-3}$), while the outer planet at $P\sim12.25$ d has $R_c=2.39_{-0.11}^{+0.10}$ $R_{\oplus}$, $M_c=8.04_{-0.48}^{+0.50}$ $M_{\oplus}$, and thus $\rho_c=3.24_{-0.43}^{+0.55}$ g cm$^{-3}$. Also considering our interior structure calculations TOI-732 b is a super-Earth and TOI-732 c is a mini-Neptune. Following the SVM approach, we quantified $\mathrm{d}\log{R_{p,{\mathrm{valley}}}}/\mathrm{d}\log{P}=-0.065_{-0.013}^{+0.024}$, which is flatter than for Sun-like stars. In line with former analyses, we noted a more filled radius valley for M-planets and we further quantified the density valley slope as $\mathrm{d}\log{\hat{\rho}_{\mathrm{valley}}}/\mathrm{d}\log{P}=-0.02_{-0.04}^{+0.12}$. Compared to FGK stars, the weaker dependence of the position of the radius valley with orbital period might indicate a heavier influence of formation relative to evolution mechanisms in shaping the radius valley around M-dwarfs.

We have undertaken a search for satellites around edge-on galaxies in the EGIPS catalog, which contains 16551 objects with declinations above -30 deg. We searched for systems with a central galaxy dominating in brightness by at least 1 mag compared to its companions. As a result, we discovered 1097 candidate satellites around 764 EGIPS galaxies with projected distances less than 500 kpc and a radial velocity difference less than 300 km/s. Of these, 757 satellites around 547 central galaxies have radial velocity accuracies higher than 20 km/s and satisfy the gravitationally bound condition. The ensemble of satellites is characterized by an average projected distance of 84 kpc and an average radial velocity dispersion of 103 km/s. Treating small satellites as test particles moving on isotropic orbits around central EGIPS galaxies, we determined the projected (orbital) masses of the edge-on galaxies. Within the luminosity range of 1.3*10^10 to 42*10^{10} Lsun, the total mass of the systems is well described by a linear dependence log(Mp)~0.88*log(<LK>g) with an average total mass-to-$K$-band luminosity equal to 17.5+-0.8 Msun/Lsun, which is typical for nearby spiral galaxies such as the Milky Way, M 31 and M 81.

Determining the mass-radius ($M$-$R$) relation of exoplanets is important for exoplanet characterization. Here we present a re-analysis of the $M$-$R$ relations and their transitions using exoplanetary data from the PlanetS catalog which accounts only for planets with reliable mass and radius determination. We find that "small planets" correspond to planets with masses of up to $7.80^{+9.74}_{-4.33} M_\oplus$ where $R \propto M^{0.41 \pm 0.09}$. Planets with masses between $7.80^{+9.74}_{-4.33} M_\oplus$ and $125^{+11}_{-10} M_\oplus$ can be viewed as "intermediate-mass" planets, where $R \propto M^{0.65 \pm 0.03}$. Massive planets, or gas giant planets, are found to have masses beyond $125^{+11}_{-10}M_\oplus$ with an $M$-$R$ relation of $R \propto M^{-0.02 \pm 0.01}$. By analyzing the radius-density relation we also find that the transition between "small" to "intermediate-size" planets occurs at a planetary radius of $1.69^{+0.45}_{-0.35}R_\oplus$. Our results are consistent with previous studies and provide an ideal fit for the currently-measured planetary population.

There exist isolated elliptical galaxies, whose dynamics can be modelled without resorting to dark matter or MOND, e.g. NGC 7507. The isolated elliptical NGC 5812 is another object to investigate a possible role of isolation. We use globular clusters (GCs) and the galaxy light itself as dynamical tracers to constrain its mass profile. We employ Gemini/GMOS mask spectroscopy, apply the GMOS reduction procedures provided within IRAF, measure GC velocities by cross correlation methods and extract the line-of-sight kinematics of galaxy spectra using the tool pPXF. We identify 28 GCs with an outermost galactocentric distance of 20 kpc, for which velocities could be obtained. Furthermore, 16 spectra of the integrated galaxy light out to 6 kpc have been used to model the central kinematics. These spectra provide evidence for a disturbed velocity field. We construct spherical Jeans models for the galaxy light and apply tracer mass estimators for the globular clusters. With the assumptions inherent to the mass estimators, MOND is compatible with the mass out to 20 kpc. However, a dark matter free galaxy is not excluded. We find one globular cluster with an estimated mass of 1.6x10**7 solar masses, the first Ultra Compact Dwarf in an isolated elliptical. We put NGC 5812 into the general context of dark matter or alternative ideas in elliptical galaxies. The case for a MONDian phenomenology also among early-type galaxies has become so strong that deviating cases appear astrophysically more interesting than agreements. The baryonic Tully Fisher relation (BTFR) as predicted by MOND is observed in some samples of early-type galaxies, in others not. However, in cases of galaxies that deviate from the MONDian prediction, data quality and data completeness are often problematic. (abridged)

The reconstruction method has been widely employed to improve the Baryon Acoustic Oscillations (BAO) measurement in spectroscopic survey data analysis. In this study, we explore the reconstruction of the BAO signals in the realm of photometric data. By adapting the Zel'dovich reconstruction technique, we develop a formalism to reconstruct the transverse BAO in the presence of photo-$z$ uncertainties. We access the performance of the BAO reconstruction through comoving $N$-body simulations. The transverse reconstruction potential can be derived by solving a 2D potential equation, with the surface density and the radial potential contribution acting as the source terms. The solution is predominantly determined by the surface density. As is evident in dense samples, such as the matter field, the transverse BAO reconstruction can enhance both the strength of the BAO signals and their cross correlation with the initial conditions. We contrast the 2D potential results with the 3D Poisson equation solution, wherein we directly solve the potential equation using the position in photo-$z$ space, and find good agreement. Additionally, we examine the impact of various conditions, such as the smoothing scales and the level of photo-$z$ uncertainties, on the reconstruction results. We envision the straightforward application of this method to survey data.

Familiar concepts in physics, such as Lorentz symmetry, are expected to be broken at energies approaching the Planck energy scale as predicted by several quantum-gravity theories. However, such very large energies are unreachable by current experiments on Earth. Current and future Cherenkov telescope facilities may have the capability to measure the accumulated deformation from Lorentz symmetry for photons traveling over large distances via energy-dependent time delays. One of the best natural laboratories to test Lorentz Invariance Violation~(LIV) signatures are Gamma-ray bursts~(GRBs). The calculation of time delays due to the LIV effect depends on the cosmic expansion history. In most of the previous works calculating time lags due to the LIV effect, the standard $\Lambda$CDM (or concordance) cosmological model is assumed. In this paper, we investigate whether the LIV signature is significantly different when assuming alternatives to the $\Lambda$CDM cosmological model. Specifically, we consider cosmological models with a non-trivial dark-energy equation of state ($w \neq -1$), such as the standard Chevallier-Polarski-Linder~(CPL) parameterization, the quadratic parameterization of the dark-energy equation of state, and the Pade parameterizations. We find that the relative difference in the predicted time lags is small, of the order of at most a few percent, and thus likely smaller than the systematic errors of possible measurements currently or in the near future.

The solar tachocline is an internal region of the Sun possessing strong radial and latitudinal shears straddling the base of the convective envelope. Based on helioseismic inversions, the tachocline is known to be thin (less than 5\% of the solar radius). Since the first theory of the solar tachocline in 1992, this thinness has not ceased to puzzle solar physicists. In this review, we lay out the grounds of our understanding of this fascinating region of the solar interior. We detail the various physical mechanisms at stake in the solar tachocline, and put a particular focus on the mechanisms that have been proposed to explain its thinness. We also examine the full range of MHD processes including waves and instabilies that are likely to occur in the tachocline, as well as their possible connection with active region patterns observed at the surface. We reflect on the most recent findings for each of them, and highlight the physical understanding that is still missing and that would allow the research community to understand, in a generic sense, how the solar tachocline and stellar tachocline are formed, are sustained, and evolve on secular timescales.

If primordial black holes constitute the dark matter, stars forming in dark-matter dominated environments with low velocity dispersions, such as ultra-faint dwarf galaxies, may capture a black hole at birth. The capture probability is non-negligible for primordial black holes of masses around $10^{20}$g, and increases with stellar mass. Moreover, infected stars are turned into virtually invisible black holes on cosmologically short timescales. Hence, the number of observed massive main-sequence stars in ultra-faint dwarfs should be suppressed if the dark matter was made of asteroid-mass primordial black holes. This would impact the measured mass distribution of stars, making it top-light (i.e. depleted in the high-mass range). Using simulated data that mimic the present-day observational power of telescopes, we show that already existing measurements of the mass function of stars in local ultra-faint dwarfs could be used to constrain the fraction of dark matter composed of primordial black holes in the -- currently unconstrained -- mass range of $10^{19}-10^{21}$g.

The high-frequency bump, characterized by a frequency exceeding ~30 Hz, represents a seldom-explored time-variability feature in the power density spectrum (PDS) of black-hole X-ray binaries. In the 2002, 2004, 2007 and 2010 outbursts of GX 339-4, the bump has been occasionally observed in conjunction with type-C quasi-periodic oscillations (QPOs). We systematically study the properties of the bump during these four outbursts observed by Rossi X-ray Timing Explorer (RXTE) in the 2-60 keV bands and detect the bump in 39 observations. While the frequencies of the type-C QPOs are in the range of ~0.1-9 Hz, the root-mean-square (rms) amplitude of the bump shows an evolution in the hardness ratio versus the type-C QPO frequency plot. By comparing the rms amplitude of the bump with the corona temperature and simultaneous radio jet flux of the source, as previously studied in GRS 1915+105, we establish that in the hard state of GX 339-4, the bump is always strong, with the measurements of the rms amplitude in the range of 4-10%. At the same time, the corona temperature is high and the radio flux is low. These findings indicate that, using the bump as a proxy, the majority of the accretion energy is directed towards the hot corona rather than being channeled into the radio jet. We discuss this phenomenon in terms of an inefficient energy transfer mechanism between the corona and jet in GX 339-4.

We investigate the properties of strong (Hb+[OIII]) emitters before and after the end of the Epoch of Reionization from z=8 to z=5.5. We make use of ultra-deep JWST/NIRCam imaging in the Parallel Field of the MIRI Deep Infrared Survey (MIDIS) in the Hubble eXtreme Deep Field (P2-XDF), in order to select prominent (Hb+[OIII]) emitters (with rest EW_0 > 100 Angstroms) at z=5.5-7, based on their flux density enhancement in the F356W band with respect to the spectral energy distribution continuum. We complement our selection with other (Hb+[OIII]) emitters from the literature at similar and higher (z=7-8) redshifts. We find (non-independent) anti-correlations between EW_0(Hb+[OIII]) and both galaxy stellar mass and age, in agreement with previous studies, and a positive correlation with specific star formation rate (sSFR). On the SFR-M* plane, the (Hb+[OIII]) emitters populate both the star-formation main sequence and the starburst region, which become indistinguishable at low stellar masses (log10(M*) < 7.5). We find tentative evidence for a non-monotonic relation between EW_0(Hb+[OIII]) and SFR, such that both parameters correlate with each other at SFR > 1 Msun/yr, while the correlation flattens out at lower SFRs. This suggests that low metallicities producing high EW_0(Hb+[OIII]) could be important at low SFR values. Interestingly, the properties of the strong emitters and other galaxies (33% and 67% of our z=5.5-7 sample, respectively) are similar, including, in many cases, high sSFR. Therefore, it is crucial to consider both emitters and non-emitters to obtain a complete picture of the cosmic star formation activity around the Epoch of Reionization.

Extreme blazars have exceptionally hard intrinsic X-ray/TeV spectra and extreme peak energies in their spectral energy distribution (SED). Observational evidence suggests that the non-thermal emission from extreme blazars is typically non-variable. We aim to explore X-ray and GeV observational features of a variety of extreme blazars and also aim to test the applicability of various blazar emission models that could explain the very hard TeV spectra. We perform X-ray analysis of AstroSat and Swift-XRT data, along with gamma-ray data from Fermi-LAT, for sources; 1ES 0120+340, RGB J0710+591, 1ES 1101-232, 1ES 1741+196 and 1ES 2322-409. We employ three models: 1) a steady-state one-zone synchrotron-self-Compton (SSC) code, 2) another leptonic scenario of co-accelerated electrons and protons on multiple shocks, applied only on the extreme-TeVsources and 3) a one-zone hadro-leptonic (OneHaLe) code. The hadro-leptonic code is used twice to explain the gamma-ray emission process: proton synchrotron and synchrotron emission of secondary pairs. Our X-ray analysis provides well-constrained estimates of the synchrotron peak energies for both 1ES0120+340 and 1ES1741+196. The multi-epoch X-ray and GeV data reveal spectral and flux variabilities in RGB J0710+591 and 1ES 1741+196, even on time scales of days to weeks. As anticipated, the one-zone SSC model adequately reproduces the SEDs of regular HBLs but encounters difficulties in explaining the hardest TeV emission. Hadronic models offer a reasonable fit to the hard TeV spectrum, though with the trade-off of requiring extreme jet powers. On the other hand, the lepto-hadronic scenario faces additional challenges in fitting the GeV spectra of extreme-TeV sources. Finally, e-p co-acceleration scenario naturally accounts for the observed hard electron distributions and effectively matches the hardest TeV spectrum of RGB J0710+591 and 1ES 1101-232.

In this paper, we present a non-Gaussianity consistency relation that enables the calculation of the squeezed limit bispectrum of the curvature perturbation in single-field inflationary models by carefully inspecting the background evolution and the linear perturbation theory. The consistency relation is more general than others in the literature since it does not require any specific symmetry, conservation of the curvature perturbation at large scales, attractor background evolution or canonical kinetic energy of the inflaton field. We demonstrate that all known examples of the squeezed limit bispectrum in single-field models of inflation can be reproduced within this framework.

In this paper, we study the evolutions of a self-gravitating cloud of bosonic dark matter with finite angular momentum and self-interaction. This is achieved by using the sixth-order pseudospectral operator splitting method to solve the system of nonlinear Schr\"odinger and Poisson equations. The initial cloud is assumed to have mass density randomly distributed throughout three-dimensional space. The dark matter particles in the initial cloud are in the kinetic regime, i.e., their de Broglie wavelength is much smaller than the halo size. It is shown that Bose stars are indeed formed in the numerical simulation presented here. The presence of angular momentum and self-interaction in the initial cloud can significantly influence the star formation time in a non-trivial fashion. Furthermore, the plots of the vorticity magnitude profile after the star formation time indicate that the formed star may not have any intrinsic angular momentum for the cases when the self-interaction among the particles is either negligible or attractive. These results are in agreement with the earlier analytical studies of an isolated rotating Bose star. However, for the case of repulsive self-interaction, the vorticity magnitude analysis shows a possibility that the star formed in the numerical simulations may possess intrinsic angular momentum. It is also shown that the average mass and radius diagrams of the star are strongly influenced by the presence of angular momentum in the initial cloud.

The signatures of polycyclic aromatic hydrocarbons (PAHs) have been observed in protoplanetary discs, and their emission features obtained from spectral energy distributions (SED) have been used in the literature to characterise their size and determine their abundance. Two simple disc models (uniform PAH distribution against a PAH gap in the inner disc) are compared to investigate the difference of their SED and obtainable information. We used the radiative transfer code RADMC-3D to model the SED of two protoplanetary discs orbiting a typical Herbig star, one of which features a depletion of PAHs in the inner disc. We further created artificial images of the discs at face-on view to extract radial profiles of the PAH emission in the infrared. We find that the extracted PAH features from an SED provide limited information about the PAHs in protoplanetary disc environments, except for the ionisation state. The distribution of PAHs in a protoplanetary disc influences the total observed PAH luminosity in a non-linear fashion and alters the relative strength between the 3.3\,$\mu$m and 11.3\,$\mu$m features. Furthermore, we produced radial profiles at the 3\,$\mu$m, 6\,$\mu$m and, 11\,$\mu$m PAH emission features and find that they follow a double power-law profile where the slope reflects the radiative environment (single photon regime vs. multi-photon regime) in which the PAHs lie. Using spatially resolved techniques such as IFU or imaging in the era of the James Webb Space Telescope, we find that multi-wavelength radial emission profiles will not only provide information on the spatial distribution of the PAHs, but may also provide information on their size and underlying UV environment, which is crucial for photo-evaporative disc wind models.

We present our photometric search for potential nuclear star clusters (NSCs) in ultra-diffuse galaxies (UDGs) as an extension of the SMUDGes catalog. We identify 325 SMUDGes galaxies with NSCs and, from the 144 with existing distance estimates, identify 33 NSC hosts as UDGs ($\mu_{0,g}$ $\ge$ 24 mag arcsec$^{-2}$, $r_e \ge 1.5$ kpc). The SMUDGes with NSCs lie on the galaxy red sequence, satisfy the NSC-host galaxy stellar mass relationship, have a mean NSC stellar mass fraction of 0.02 but reach as high as 0.1, have NSCs that are displaced from the host center with a standard deviation of 0.10$r_e$, and weakly favor higher density environments. All of these properties are consistent with previous results from higher surface brightness galaxy samples, allowing for at most a relatively weak dependence of NSC behavior with host galaxy surface brightness.

We apply neural posterior estimation for fast-and-accurate hierarchical Bayesian inference of gravitational wave populations. We use a normalizing flow to estimate directly the population hyper-parameters from a collection of individual source observations. This approach provides complete freedom in event representation, automatic inclusion of selection effects, and (in contrast to likelihood estimation) without the need for stochastic samplers to obtain posterior samples. Since the number of events may be unknown when the network is trained, we split into sub-population analyses that we later recombine; this allows for fast sequential analyses as additional events are observed. We demonstrate our method on a toy problem of dark siren cosmology, and show that inference takes just a few minutes and scales to $\sim 600$ events before performance degrades. We argue that neural posterior estimation therefore represents a promising avenue for population inference with large numbers of events.

Searching for gravitational-wave signals is a challenging and computationally intensive endeavor undertaken by multiple independent analysis pipelines. While detection should depend only on the observed noisy data, there are situations where it is instead unphysically defined in terms also of the true source parameters through the optimal signal-to-noise ratio (SNR). For example, the computational cost of applying real searches is often too prohibitive for large simulated astrophysical populations to create predictive catalogs. By simultaneously modeling selection effects and the intrinsic SNR distribution, we infer the corresponding detection threshold from the real catalog in a Bayesian setting, thereby calibrating the unphysical model to the physical one. From the latest open data we infer detection thresholds in the network optimal SNR of $10.5_{-2.4}^{+2.1}$, $11.2_{-1.4}^{+1.2}$, and $9.1_{-0.5}^{+0.5}$ (medians and symmetric 90% credible intervals) for the first, second, and third observing runs, respectively, and that the distribution is consistent with a fourth-order power law. We additionally relax the assumption of a step-function threshold and show how the assumed distribution can be validated with more flexible models such as normalizing flows, which is useful for ranking statistics with no obvious prior. Employing the same detection criteria that we infer will allow modelers to apply approximate but efficient selection effects calibrated to full searches on real signals.

Resonant interactions between relativistic electrons and electromagnetic ion cyclotron (EMIC) waves provide an effective loss mechanism for this important electron population in the outer radiation belt. The diffusive regime of electron scattering and loss has been well incorporated into radiation belt models within the framework of the quasi-linear diffusion theory, whereas the nonlinear regime has been mostly studied with test particle simulations. There is also a less investigated, nonresonant regime of electron scattering by EMIC waves. All three regimes should be present, depending on the EMIC waves and ambient plasma properties, but the occurrence rates of these regimes have not been previously quantified. This study provides a statistical investigation of the most important EMIC wave-packet characteristics for the diffusive, nonlinear, and nonresonant regimes of electron scattering. We utilize 3 years of Van Allen Probe observations to derive distributions of wave amplitudes, wave-packet sizes, and rates of frequency variations within individual wave-packets. We demonstrate that EMIC waves typically propagate as wave-packets with $\sim 10$ wave periods each, and that $\sim 3-10$\% of such wave-packets can reach the regime of nonlinear resonant interaction with 2 to 6 MeV electrons. We show that EMIC frequency variations within wave-packets reach $50-100$\% of the center frequency, corresponding to a significant high-frequency tail in their wave power spectrum. We explore the consequences of these wave-packet characteristics for high and low energy electron precipitation by H-band EMIC waves and for the relative importance of quasi-linear and nonlinear regimes of wave-particle interactions.

In this Letter, three analytical models are constructed in closed forms, each representing a supermassive black hole (SMBH) located at the center of a galaxy surrounded by a dark matter halo.The latter is modeled by the Einstein cloud. The density profile of the halo vanishes inside two Schwarzschild radii of the SMBH and satisfies the weak, strong and dominant energy conditions.The spacetime is asymptotically flat, and the difference among the three models lies in the slopes of the density profiles in the far region from the galaxy center.

In this study, we introduce an innovative Quantum-enhanced Support Vector Machine (QSVM) approach for stellar classification, leveraging the power of quantum computing and GPU acceleration. Our QSVM algorithm significantly surpasses traditional methods such as K-Nearest Neighbors (KNN) and Logistic Regression (LR), particularly in handling complex binary and multi-class scenarios within the Harvard stellar classification system. The integration of quantum principles notably enhances classification accuracy, while GPU acceleration using the cuQuantum SDK ensures computational efficiency and scalability for large datasets in quantum simulators. This synergy not only accelerates the processing process but also improves the accuracy of classifying diverse stellar types, setting a new benchmark in astronomical data analysis. Our findings underscore the transformative potential of quantum machine learning in astronomical research, marking a significant leap forward in both precision and processing speed for stellar classification. This advancement has broader implications for astrophysical and related scientific fields

We study the cosmological evolution of a FLRW universe dominated by the energy density of moduli close to asymptotic regions of moduli space. Due to the structure of the $\mathcal{N}=1$ SUGRA kinetic term, a saxion and an axion residing in the same chiral multiplet are (universally) coupled even if the latter is a flat direction of the potential, resulting in non-trivial dynamics. We generalise known results in the literature to the case of multiple moduli, showing the existence of various ``tracker" attractor solutions where the relative energy densities of many components (axions included) stay in a fixed ratio throughout the evolution. We conclude with some phenomenological applications, relevant for both the early and late universe.

We explore the phenomenological consequences of breaking discrete global symmetries in quantum gravity (QG). We extend a previous scenario where discrete global symmetries are responsible for scalar dark matter (DM) and domain walls (DWs), to the case of fermionic DM, considered as a feebly interacting massive particle, which achieves the correct DM relic density via the freeze-in mechanism. Due to the mixing between DM and the standard model neutrinos, various indirect DM detection methods can be employed to constrain the QG scale, the scale of freeze-in, and the reheating temperature simultaneously. Since such QG symmetry breaking leads to DW annihilation, this may generate the characteristic gravitational wave background, and hence explain the recent observations of the gravitational wave spectrum by pulsar timing arrays. This work therefore highlights a tantalizing possibility of probing the effective scale of QG from observations.

In this paper, we investigate the evolution of strange quark stars (SQS) from birth as proto-strange quark stars to maturity as stable SQSs at a zero temperature. We assume that self-bound free quarks form neutron stars (NS) and study their evolution using a density-dependent quark mass model. We consider $\beta$-equilibrium stellar matter at two major stages of the star's evolution: neutrino trapped regime and neutrino transparent regime during the deleptonization and cooling processes of the star. We fix the entropy density and investigate the nuclear equation of state (EoS), particle distribution and temperature profile inside the star, sound velocity, polytropic index, and the structure of the star. Our results show that stars with higher neutrino concentrations are slightly more massive than the neutrino-poor ones along the evolution lines of the SQS. We obtain EoSs in agreement with the conformal boundary set through sound velocity, and also the 2 M$_\odot$ mass constraint for NSs was satisfied at all stages of the star's evolution.

The Hamiltonian analysis for $f(T)$ gravity implies the existence of at least one scalar-type degree of freedom (DoF). However, this scalar DoF of $f(T)$ gravity does not manifest in linear perturbations around a cosmological background, which indicates an underlying strong coupling problem. In this work we expand the scope by introducing an extra scalar field non-minimally coupled to $f(T)$ gravity, aiming to address or alleviate the aforementioned strong coupling problem. Employing the effective field theory (EFT) approach, we provide a class of torsional EFT forms up to second order operators, avoiding the Ostrogradsky ghost. To illustrate this phenomenon, we study a simple model and perform a detailed analysis of its linear scalar perturbations. The results demonstrate that the coupling terms in this toy model are necessary to avoid the initial degenerate situation. The complete avoidance of new constraints requires more coupling terms. Once this vanishing scalar DoF starts propagating in cosmological background at linear level, this phenomenon will demand a revisit of the strong coupling issue that arises in $f(T)$ gravity, particularly in the presence of matter coupling.

Parallel plate capacitors (PPC) significantly reduce the size of superconducting microwave resonators, reducing the pixel pitch for arrays of single photon energy-resolving kinetic inductance detectors (KIDs). The frequency noise of KIDs is typically limited by tunneling Two-Level Systems (TLS), which originate from lattice defects in the dielectric materials required for PPCs. How the frequency noise level depends on the PPC's dimensions has not been experimentally addressed. We measure the frequency noise of 56 resonators with a-SiC:H PPCs, which cover a factor 44 in PPC area and a factor 4 in dielectric thickness. To support the noise analysis, we measure the TLS-induced, power-dependent, intrinsic loss and temperature-dependent resonance frequency shift of the resonators. From the TLS models, we expect a geometry-independent microwave loss and resonance frequency shift, set by the TLS properties of the dielectric. However, we observe a thickness-dependent microwave loss and resonance frequency shift, explained by surface layers that limit the performance of PPC-based resonators. For a uniform dielectric, the frequency noise level should scale directly inversely with the PPC area and thickness. We observe that an increase in PPC size reduces the frequency noise, but the exact scaling is, in some cases, weaker than expected. Finally, we derive an engineering guideline for the design of KIDs based on PPC-based resonators.

We investigate the stochastic gravitational wave (GW) spectrum resulting from graviton bremsstrahlung during inflationary reheating. We focus on an inflaton $\phi$ oscillating around a generic monomial potential $V(\phi) \propto \phi^n$, considering two different reheating scenarios: $i)$ inflaton decay and $ii)$ inflaton annihilation. We show that in the case of a quadratic potential, the scattering of the inflatons can give rise to larger GW amplitude than the decay channel. On the other hand, the GW spectrum exhibits distinct features and redshifts in each scenario, which makes it possible to distinguish them in the event of a discovery. Specifically, in the case of annihilation, the GW frequency can be shifted to values higher than those of decay, whereas the GW amplitude generated by annihilation turns out to be smaller than that in the decay case for $n \geq 4$, due to the different scaling of radiation during reheating. We also show that the differences in the GW spectrum become more prominent with increasing $n$. Finally, we highlight the potential of future high-frequency GW detectors to distinguish between the different reheating scenarios.

Extraction of multiple quasinormal modes from ringdown gravitational waves emitted from a binary black hole coalescence is a touchstone to test whether a remnant black hole is described by the Kerr spacetime in general relativity. However, it is not straightforward to check the consistency between the ringdown signal and the quasinormal mode frequencies predicted by the linear perturbation theory. While the longest-lived mode can be extracted in a stable manner, the higher overtones damp more quickly and hence the fitting of overtones tends to end up with the overfit. To improve the extraction of overtones, we propose an iterative procedure consisting of fitting and subtraction of the longest-lived mode of the ringdown waveform in the time domain. Through the analyses of the mock waveform and numerical relativity waveform, we clarify that the iterative procedure allows us to extract the overtones in a more stable manner.