Papers for Tuesday, Sep 27 2022

FIRSTv2 (Fibered Imager foR a Single Telescope version 2) is the upgrade of a post-AO spectro-interferometer (FIRST) that enables high contrast imaging and spectroscopy at spatial scales below the diffraction limit of a single telescope. FIRST is currently installed, and routinely used, on the Subaru telescope as a module of the Subaru Extreme AO (SCExAO) platform. It achieves sensitivity and accuracy by a unique combination of sparse aperture masking, spatial filtering by single-mode fibers and cross-dispersion in the visible (600-900nm). The ongoing upgrade aims at using a photonic chip beam combiner, allowing the measurement of the complex visibility for every baseline independently. Using the integrated optics technology will increase the stability and sensitivity, and thus improve the dynamic range. Integrated optics chips working in the visible wavelength range are challenging (in terms of throughput and polarization). Several photonic chips are under characterization in our laboratory and we have installed a first prototype chip in the FIRSTv2 instrument at the Subaru Telescope. I will thus report on the on-sky results obtained with this kind of device, for the first time in the visible. This is the first step towards the full upgrade of FIRSTv2, that will ultimately provide unique capabilities to detect and characterize close companions such as exoplanets, by combining high angular resolution and spectral resolution in the visible.

Debris disks are dusty, optically thin structures around main sequence stars. HD 106906AB is a short-period stellar binary, host to a wide separation planet, HD 106906b, and a debris disk. Only a few known systems include a debris disk and a directly imaged planet, and HD 106906 is the only one in which the planet is exterior to the disk. The debris disk is edge-on and highly asymmetric in scattered light. Here we resolve the disk structure at a resolution of 0.38" (39 au) with the Atacama Large Millimeter/submillimeter Array (ALMA) at a wavelength of 1.3 mm. We model the disk with both a narrow and broad ring of material, and find that a radially broad, axisymmetric disk between radii of $\sim$50$-$100 au is able to capture the structure of the observations without evidence of any asymmetry or eccentricity, other than a tentative stellocentric offset. We place stringent upper limits on both the gas and dust content of a putative circumplanetary disk. We interpret the ALMA data in concert with scattered light observations of the inner ring and astrometric constraints on the planet's orbit, and find that the observations are consistent with a large-separation, low-eccentricity orbit for the planet. A dynamical analysis indicates that the central binary can efficiently stabilize planetesimal orbits interior to $\sim$100 au, which relaxes the constraints on eccentricity and semimajor axis somewhat. The observational constraints are consistent with in situ formation via gravitational instability, but cannot rule out a scattering event as the origin for HD 106906b's current orbit.

Strong gravitational lensing (SL) has emerged as a very accurate probe of the mass distribution of cluster- and galaxy-scale dark matter (DM) haloes in the inner regions of galaxy clusters. The derived properties of DM haloes can be compared to the predictions of high-resolution cosmological simulations, providing us with a test of the Standard Cosmological Model. The usual choice of simple power-law scaling relations to link the total mass of members with their luminosity is one of the possible inherent systematics within SL models of galaxy clusters, and thus on the derived cluster masses. Using new information on their structural parameters (from HST imaging) and kinematics (from MUSE data), we build the Fundamental Plane (FP) for the early-type galaxies of the cluster Abell S1063. We take advantage of the calibrated FP to develop an improved SL model of the total mass of the cluster core. The new method allows us to obtain more accurate and complex relations between the observables describing cluster members, and to completely fix their mass from their observed magnitudes and effective radii. Compared to the power-law approach, we find a different relation between the mass and the velocity dispersion of members, which shows a significant scatter. Thanks to a new estimate of the stellar mass of the cluster members from HST data, we measure the cumulative projected mass profiles out to a radius of 350 kpc, for all baryonic and DM components of the cluster. Finally, we compare the physical properties of the sub-haloes in our model and those predicted by high-resolution hydrodynamical simulations. We obtain compatible results in terms of the stellar-over-total mass fraction of the members. On the other hand, we confirm the recently reported discrepancy in terms of sub-halo compactness: at a fixed total mass value, simulated sub-haloes are less compact than what our SL model predicts.

HD106906 is a planetary system that hosts a wide-orbit companion, as well as an eccentric and flat debris disk, which hold important constraints on its formation and subsequent evolution. The recent observations of the companion constrain its orbit to be eccentric and inclined relative to the plane of the debris disk. Here, we show that, in the presence of the inclined companion, the debris disk quickly ($\lesssim5$ Myr) becomes warped and puffy. This suggests that the current configuration of the system is relatively recent. We explore the possibility that a recent close encounter with a free floating planet could produce a companion with orbital parameters that agree with observations of HD106906b. We find that this scenario is able to recreate the structure of the debris disk while producing a companion in agreement with observation.

We present a detailed chemical abundance analysis of the young massive cluster (YMC) NGC 1569-B. The host galaxy, NGC~1569, is a dwarf irregular starburst galaxy at a distance of 3.36$\pm$0.20 Mpc. We determined the abundance ratios from the analysis of an optical integrated-light spectrum of NGC 1569-B, obtained with the HIRES echelle spectrograph on the Keck I telescope. We considered different red-to-blue supergiant ratios, namely: the ratio obtained from a theoretical isochrone, the ratio obtained from a resolved colour-magnitude diagram of the YMC, and the ratio that minimises the $\chi^2$ when comparing our model spectra with the observations. We adopted the latter ratio for our resulting chemical abundances. The derived iron abundance is sub-solar with [Fe/H] = $-0.74\pm0.05$. In relation to the scaled solar composition, we find enhanced $\alpha$-element abundances, $\text{[<Mg,Si,Ca,Ti>/Fe]}=+0.25\pm$0.11, with a particularly high Ti abundance of +0.49$\pm$0.05. Other super-solar elements include $\text{[Cr/Fe]}=+0.50\pm$0.11, $\text{[Sc/Fe]}=+0.78\pm$0.20, and $\text{[Ba/Fe]}=+1.28\pm$0.14, while other Fe-peak elements are close to scaled solar abundances: ($\text{[Mn/Fe]}=-0.22\pm$0.12 and $\text{[Ni/Fe]}=+0.13\pm$0.11). The composition of NGC 1569-B resembles the stellar populations of the YMC NGC 1705-1, located in a blue compact dwarf galaxy. The two YMCs agree with regard to $\alpha$-elements and the majority of the Fe-peak elements, except for Sc and Ba, which are extremely super-solar in NGC~1569-B -- and higher than in any YMC studied so far. The blue part of the optical spectrum of a young population is still a very challenging wavelength region to analyse using IL spectroscopic studies. This is due to the uncertain contribution to the light from blue supergiant stars, which can be difficult to disentangle from turn-off stars, even when resolved photometry is available.

We report on the discovery of linear filaments observed in CO(1-0) emission for a $\sim2'$ field of view toward the Sgr E star forming region centered at (l,b)=(358.720$^\circ$, 0.011$^\circ$). The Sgr E region is thought to be at the turbulent intersection of the ''far dust lane'' associated with the Galactic bar and the Central Molecular Zone (CMZ). This region is subject to strong accelerations which are generally thought to inhibit star formation, yet Sgr E contains a large number of HII regions. We present $^{12}$CO(1-0), $^{13}$CO(1-0), and C$^{18}$O(1-0) spectral line observations from ALMA and provide measurements of the physical and kinematic properties for two of the brightest filaments. These filaments have widths (FWHM) of $\sim0.1$ pc and are oriented nearly parallel to the Galactic plane, with angles from the Galactic plane of $\sim2^\circ$. The filaments are elongated, with lower limit aspect ratios of $\sim$5:1. For both filaments we detect two distinct velocity components that are separated by about 15 km s$^{-1}$. In the C$^{18}$O spectral line data with $\sim$0.09 pc spatial resolution, we find that these velocity components have relatively narrow ($\sim$1-2 km s$^{-1}$) FWHM linewidths when compared to other sources towards the Galactic center. The properties of these filaments suggest that the gas in the Sgr E complex is being ''stretched'' as it is rapidly accelerated by the gravitational field of the Galactic bar while falling towards the CMZ, a result that could provide insight into the extreme environment surrounding this region and the large-scale processes which fuel this environment.

We examine the gas content of field dwarf galaxies in a high-resolution cosmological simulation. In agreement with previous work, we find that galaxies inhabiting dark matter haloes with mass below a critical value, $M_{200} \lesssim M_{\rm crit} \approx 5\times 10^{9} \ M_{\odot}$, are quiescent at the present day. The gas content of these galaxies is thus insensitive to feedback from evolving stars. Almost half of these quiescent systems today have gas masses much smaller than that expected for their mass. We find that gas-deficient galaxies originate from 1) past interactions with massive hosts, in which a dwarf loses gas and dark matter via tidal and ram-pressure forces; and 2) from hydrodynamic interactions with the gaseous filaments and sheets of the cosmic web, in which a dwarf loses gas via ram-pressure. We refer to these systems as ``flybys'' and ``COSWEBs''. Flybys locate in high-density regions, tracing the location of the most massive galaxies in the simulation. In contrast, COSWEBs are dispersed throughout the volume and trace the cosmic web. For sub-critical systems, $M_{200} < M_{\rm crit}$, the fraction of COSWEB galaxies can be as high as $35 \%$, and much higher for flybys, which make up 100 per cent of the galaxies with $M_{200}<3\times 10^8 \ \rm M_{\odot}$. The deficit of gas caused by these mechanisms may preclude the detection of a large fraction of field dwarfs in future HI surveys. For galaxies inhabiting halos with mass $M_{200} > M_{\rm crit}$, we find that cosmic web stripping, on average, shuts down star formation in more than $70\%$ of the affected systems.

We investigate how the environment affects the assembly history of massive galaxies. For that purpose, we make use of SHARDS and HST spectro-photometric data, whose depth, spectral resolution, and wavelength coverage allow to perform a detailed analysis of the stellar emission as well as obtaining unprecedentedly accurate photometric redshifts. This expedites a sufficiently accurate estimate of the local environment and a robust derivation of the star formation histories of a complete sample of 332 massive galaxies ($\mathrm{>10^{10}M_{\odot}}$) at redshift $1\leq z \leq 1.5$ in the GOODS-N field. We find that massive galaxies in this redshift range avoid the lowest density environments. Moreover, we observed that the oldest galaxies in our sample with with mass-weighted formation redshift $\mathrm{\overline{z}_{M-w} \geq 2.5}$, avoid the highest density regions, preferring intermediate environments. Younger galaxies, including those with active star formation, tend to live in denser environments ($\Sigma = \mathrm{5.0_{1.1}^{24.8}\times 10^{10}M_{\odot}Mpc^{-2}}$). This behavior could be expected if those massive galaxies starting their formation first would merge with neighbors and sweep their environment earlier. On the other hand, galaxies formed more recently ($\overline{z}_{M-w} < 2.5$) are accreted into large scale structures at later times and we are observing them before sweeping their environment or, alternatively, they are less likely to affect their environment. However, given that both number and mass surface densities of neighbor galaxies is relatively low for the oldest galaxies, our results reveal a very weak correlation between environment and the first formation stages of the earliest massive galaxies.

We report the discovery of widespread maser emission in non-metastable inversion transitions of NH$_3$ toward various parts of the Sagittarius B2 molecular cloud/star forming region complex: We detect masers in the $J,K = $ (6,3), (7,4), (8,5), (9,6), and (10,7) transitions toward Sgr B2(M) and Sgr B2(N), an NH$_3$ (6,3) maser in Sgr B2(NS), and NH$_3$ (7,4), (9,6), and (10,7) masers in Sgr B2(S). With the high angular resolution data of the Karl G. Jansky Very Large Array (JVLA) in A-configuration we identify 18 maser spots. Nine maser spots arise from Sgr B2(N), one from Sgr B2(NS), five from Sgr B2(M), and three in Sgr B2(S). Compared to our Effelsberg single dish data, the JVLA data indicate no missing flux. The detected maser spots are not resolved by our JVLA observations. Lower limits to the brightness temperature are $>$3000~K and reach up to several 10$^5$~K, manifesting the lines' maser nature. In view of the masers' velocity differences with respect to adjacent hot molecular cores and/or UCH{\scriptsize II} regions, it is argued that all the measured ammonia maser lines may be associated with shocks caused either by outflows or by the expansion of UCH{\scriptsize II} regions. Overall, Sgr B2 is unique in that it allows us to measure many NH$_3$ masers simultaneously, which may be essential to elucidate their so far poorly understood origin and excitation.

Atomic and molecular data are required to conduct detailed calculations of microphysical processes performed by CLOUDY to predict the spectra of a theoretical model. One of the three databases CLOUDY currently utilizes is CHIANTI version 7.1. CHIANTI version 10.0.1 is available, but its format has changed. CLOUDY is incompatible with the newer version. We have developed a script to convert the version 10.0.1 database into its version 7.1 format so that CLOUDY does not have to change every time there is a new CHIANTI version with an evolved format. This study outlines the steps taken by the script for this version format change. We have also found a modest number of significant changes to spectral line intensities/luminosities calculated by CLOUDY with the adoption of CHIANTI version 10.0.1. These changes are a result of improvements to collision strength data.

The Double Pulsar, PSR J0737-3039A/B, has offered a wealth of gravitational experiments in the strong-field regime, all of which GR has passed with flying colours. In particular, among current gravity experiments that test photon propagation, the Double Pulsar probes the strongest spacetime curvature. Observations with MeerKAT and, in future, the SKA can greatly improve the accuracy of current tests and facilitate tests of NLO contributions in both orbital motion and signal propagation. We present our timing analysis of new observations of PSR J0737-3039A, made using the MeerKAT telescope over the last 3 years. The increased timing precision offered by MeerKAT yields a 2 times better measurement of Shapiro delay parameter s and improved mass measurements compared to previous studies. In addition, our results provide an independent confirmation of the NLO signal propagation effects and already surpass the previous measurement from 16-yr data by a factor of 1.65. These effects include the retardation effect due to the movement of B and the deflection of the signal by the gravitational field of B. We also investigate novel effects which are expected. For instance, we search for potential profile variations near superior conjunctions caused by shifts of the line-of-sight due to latitudinal signal deflection and find insignificant evidence with our current data. With simulations, we find that the latitudinal deflection delay is unlikely to be measured with timing because of its correlation with Shapiro delay. Furthermore, although it is currently not possible to detect the expected lensing correction to the Shapiro delay, our simulations suggest that this effect may be measured with the full SKA. Finally, we provide an improved analytical description for the signal propagation in the Double Pulsar system that meets the timing precision expected from future instruments such as the full SKA.

The unknown intrinsic shape of source galaxies is one of the largest uncertainties of weak gravitational lensing (WL). It results in the so-called shape noise at the level of $\sigma_\epsilon^{\mathrm{WL}} \approx 0.26$, whereas the shear effect of interest is of order percent. Kinematic lensing (KL) is a new technique that combines photometric shape measurements with resolved spectroscopic observations to infer the intrinsic galaxy shape and directly estimate the gravitational shear. This paper presents a KL inference pipeline that jointly forward-models galaxy imaging and slit spectroscopy to extract the shear signal. We build a set of realistic mock observations and show that the KL inference pipeline can robustly recover the input shear. To quantify the shear measurement uncertainty for KL, we average the shape noise over a population of randomly oriented disc galaxies and estimate it to be $\sigma_\epsilon^{\mathrm{KL}}\approx 0.022-0.041$ depending on emission line signal-to-noise. This order of magnitude improvement over traditional WL makes a KL observational program feasible with existing spectroscopic instruments. To this end, we characterize the dependence of KL shape noise on observational factors and discuss implications for the survey strategy of future KL observations. In particular, we find that prioritizing quality spectra of low inclination galaxies is more advantageous than maximizing the overall number density.

Regularized Maximum Likelihood (RML) techniques are a class of image synthesis methods that have the potential to achieve improved angular resolution and image fidelity compared to traditional image synthesis methods like CLEAN when applied to sub-mm interferometric observations. We used the GPU-accelerated open source Python package MPoL to explore the influence of various RML prior distributions (maximum entropy, sparsity, total variation, and total squared variation) on images reconstructed from ALMA continuum observations of the protoplanetary disk hosted by HD 143006. We developed a K-fold process for the image validation procedure cross-validation (CV) and explored both uniform and "dartboard" styles of visibility sampling within the validation process. Using CV to find optimal hyperparameter values for the test case of total squared variation regularization, we discovered that a wide range of hyperparameter values (spanning roughly an order of magnitude) correspond to models with strong predictive power for visibilities across unsampled or sparsely sampled spatial frequencies. We also provide a comparison of RML and CLEAN images for the protoplanetary disk around HD 143006, finding that RML imaging improves the spatial resolution of the image by about a factor of 3. Lastly, we distill general recommendations for building an RML workflow for image synthesis of ALMA protoplanetary disk observations, including recommendations for incorporating CV most effectively. Using RML methods to improve the resolution of protoplanetary disk observations will enable new science requiring high resolution images, including the detection of protoplanets embedded within disks.

In the last 20 years, modern wide-field surveys discovered a new class of peculiar transients, which lie in the luminosity gap between standard supernovae and classical novae. These transients are often called 'intermediate luminosity optical transients' or 'gap transients'. They are usually distinguished in subgroups based on their phenomenology, such as supernova impostors, intermediate luminosity red transients, and luminous red novae. In this review, we present a brief overview of their observational features and possible physical scenarios to date, in the attempt to understand their nature.

This work extends a contemporaneous effort (Panaitescu & Vestrand 2022) to study the properties of the lower-energy counterpart synchrotron emission produced by the cooling of relativistic Gamma-Ray Burst (GRB) electrons through radiation (synchrotron and self-Compton) emission and adiabatic losses. We derive the major characteristics (pulse duration, lag-time after burst, brightness relative to the burst) of the Prompt Optical Counterpart (POC) accompanying GRBs. Depending on the magnetic field life-time, duration of electron injection, and electron transit-time Dto from hard X-ray (GRB) to optical emitting energies, a (true) POC may appear during the GRB pulse (of duration dtg) or after (delayed OC). The signature of counterparts arising from the cooling of GRB electrons is that true POC pulses (Dto < dtg) last as long as the corresponding GRB pulse (dto ~ dtg) while delayed OC pulses (Dto > dtg) last as long as the transit-time (dto ~ Dto). If OC variability can be measured, then another signature for this OC mechanism is that the GRB variability is "passed" only to POCs but is lost for delayed OCs. Within the GRB electron cooling model for counterparts, POCs should be on average dimmer than delayed one (which is found to be consistent with the data), and harder GRB low-energy slopes bLE should be associated more often with the dimmer POCs The range of low-energy slopes bLE in [-1/2,1/3] produced by electron cooling and the average burst brightness of 1 mJy (with 1 dex dispersion) imply that POCs of hard GRBs can be dimmer than R=20 and difficult to detect by robotic telescopes (unless there is another mechanism that overshines the emission from cooling electrons) and that the POCs of soft GRBs can be brighter than R=10, i.e. as bright as the Optical Flashes (OFs) seen for several bursts.

There are at least 125 Galactic pulsar wind nebulae (PWNe) that have been discovered from radio wavelengths to TeV gamma-rays, the majority of which were first identified in radio or X-ray surveys. An increasing number of PWNe are being identified in the TeV band by ground-based air Cherenkov Telescopes such as HESS, MAGIC, and VERITAS such that they constitute the dominant source class of Galactic TeV emitters. Combining available MeV-GeV data with observations in the TeV band is critical for precise characterization of high-energy emission from the relativistic particle population in PWNe, thus revealing the capability to produce a significant fraction of the detected Galactic CR flux. However, MeV-GeV PWN counterparts are still largely lacking even after 12 years of continuous observation of the entire sky. Less than a dozen PWNe are currently identified by the Fermi-LAT in the MeV-GeV band. Most PWNe are located along the Galactic plane embedded within the prominent, diffuse Galactic gamma-ray emission, which makes these sources difficult to disentangle from the bright diffuse background. We present a systematic search for gamma-ray counterparts to known PWNe in the 300MeV - 2TeV energy band using 11.5 years of Fermi-LAT data. For the first part of this search, we target the locations of PWNe previously identified across the electromagnetic spectrum that are not powered by pulsars previously detected by the Fermi-LAT as pulsating gamma-ray signals, which includes 6 Fermi PWNe and 7 Fermi PWN associations. We report the analysis of 58 total regions of interest and provide all firm and tentative detections along with their morphological and spectral characteristics. There are 11 unidentified gamma-ray sources that we classify as firm PWN counterparts, which doubles the PWN population detected by the Fermi-LAT, and 22 gamma-ray sources that are PWN candidates.

NASA's Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ~10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos's response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor $\beta$, showing that a particular direction-specific $\beta$ will be directly determined by the DART results, and that a related direction-specific $\beta$ is a figure of merit for a kinetic impact mission. The DART $\beta$ determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos's near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in-situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction.

NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of the kinetic impactor method for asteroid deflection, in which a spacecraft intentionally impacts an asteroid to change its trajectory. DART represents an important first step for planetary defense technology demonstration, providing a realistic assessment of the effectiveness of the kinetic impact approach on a near-Earth asteroid. The momentum imparted to the asteroid is transferred from the impacting spacecraft and enhanced by the momentum of material ejected from the impact site. However, the magnitude of the ejecta contribution is dependent on the material properties of the target. These properties, such as strength and shear modulus, are unknown for the DART target asteroid, Dimorphos, as well as most asteroids since such properties are difficult to characterize remotely. This study examines how hydrocode simulations can be used to estimate material properties from information available post-impact, specifically the asteroid size and shape, the velocity and properties of the impacting spacecraft, and the final velocity change imparted to the asteroid. Across >300 three-dimensional simulations varying seven material parameters describing the asteroid, we found many combinations of properties could reproduce a particular asteroid velocity. Additional observations, such as asteroid mass or crater size, are required to further constrain properties like asteroid strength or outcomes like the momentum enhancement provided by impact ejecta. Our results demonstrate the vital importance of having as much knowledge as possible prior to an impact mission, with key material parameters being the asteroid's mass, porosity, strength, and elastic properties.

Molecules reside broadly in the interstellar space and can be detected via spectroscopic observations. To date, more than 271 molecular species have been identified in interstellar medium or circumstellar envelopes. Molecular spectroscopic parameters measured in laboratory make the identification of new species and derivation of physical parameters possible. These spectroscopic parameters are systematically collected into databases, two of the most commonly used being the CDMS and JPL databases. While new spectroscopic parameters are continuously measured/calculated and added to those databases, at any point in time it is the existing spectroscopic data that ultimately limits what molecules can possibly be identified in astronomical data. In this work, we conduct a meta-analysis of the CDMS and JPL databases. We show the statistics of transition frequencies and their uncertainties in these two databases, and discuss the line confusion problem under certain physical environments. We then assess the prospects of detecting molecules in common ISM environments using a few facilities that are expected to be conducting spectroscopic observations in the future. Results show that CSST/HSTDM and SKA1-mid have the potential to detect some complex organic molecules, or even amino acids, with reasonable assumptions about ISM environments.

Recent spectroscopic explorations of large Galactic stellar samples stars have revealed the existence of red giants with [{\alpha}/Fe] ratios anomalously high given their relatively young ages. We revisit the GALAH DR3 survey to look for both dwarf and giant stars with extreme [{\alpha}/Fe] ratios, i.e., upper 1% in the [{\alpha}/Fe]-[Fe/H] plane over the range in [Fe/H] between -1.1 and +0.4 dex. We call these outliers ex{\alpha}fe stars. We use the GALAH DR3 data along with their Value-Added Catalogue to trace the properties (chemical abundances, masses, ages, and kinematics) of the ex{\alpha}fe. We investigate the effects of secular stellar evolution and of the magnitude limitations of the GALAH survey to understand the mass and metallicity distributions of the sample stars and discuss the corresponding biases in previous studies of stars with high - though not extreme - [{\alpha}/Fe] in other spectroscopic surveys. We find both dwarf and giant ex{\alpha}fe stars younger than 3 Gyr, that we call y-ex{\alpha}fe. Dwarf y-ex{\alpha}fe stars exhibit lithium abundances similar to those of young [{\alpha}/Fe]-normal dwarfs at the same age and [Fe/H]. In particular, the youngest and most massive stars of both populations exhibit the highest Li abundances, A(Li){\sim}3.5 dex, while cooler and/or older stars exhibit the same Li depletion patterns increasing with both decreasing mass and increasing age. In addition, the [Fe/H] and mass distributions of both the dwarf and giant y-ex{\alpha}fe stars do not differ from those of their [{\alpha}/Fe]-normal counterparts found in the thin disk, and they share the same kinematic properties. We conclude that y-ex{\alpha}fe dwarf and giant stars are indeed young, that their mass distribution shows no peculiarity, and that they differ from young [{\alpha}/Fe]-normal stars by their extreme [{\alpha}/Fe] content only. However, their origin remains unclear.

Visual magnitudes and sky coordinates are projected for the full constellation of Starlink satellites. The results are presented in the form of sky maps and numerical tables. Observer latitudes from the equator to 60 degrees are considered. The solar elevations include -12 deg (the end of nautical twilight), -18 deg (the end of astronomical twilight) and -30 deg.

An incremental version of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi-Large Area Telescope is presented. This version (4LAC-DR3) derives from the third data release of the 4FGL catalog based on 12 years of E>50 MeV gamma-ray data, where the spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates and four radio galaxies. We describe the properties of the new sample and outline changes affecting the previously published one. We also introduce two new parameters in this release, namely the peak energy of the SED high-energy component and the corresponding flux. These parameters allow an assessment of the Compton dominance, the ratio of the Inverse-Compton to the synchrotron peak luminosities, without relying on X-ray data.

We present two general relativistic radiation magnetohydrodynamics (GRRMHD) simulations of magnetically arrested disks (MADs) around non-spinning ($a_*=0$) and spinning ($a_*=0.9$) supermassive black holes (BHs). In each simulation, the mass accretion rate is decreased with time such that we sample Eddington-scaled rates over the range $3 \gtrsim \dot{M}/\dot{M}_{\rm{Edd}}\gtrsim 0.3$. For the non-spinning BH model, the total and radiative efficiencies increase as the accretion rate decreases, varying over the range $\eta_{\rm{tot}}\sim9-16\%$ and $\eta_{\rm{rad}}\sim6-12\%$, respectively. This model shows very little jet activity. In contrast, the spinning BH model has a strong relativistic jet powered by spin energy extracted from the BH. The jet power declines with accretion rate such that $\eta_{\rm{jet}}\sim 18-39\%$ while the total and radiative efficiencies are $\eta_{\rm{tot}}\sim 64-100\%$ and $\eta_{\rm{rad}}\sim 45-79\%$, respectively. We confirm that mildly sub-Eddington disks can extract substantial power from a spinning BH, provided they are in the MAD state. The jet profile out to $100\, GM/c^2$ is roughly parabolic with a power-law index of $k\approx0.43-0.53$ during the sub-Eddington evolution. Both models show significant variability in the outgoing radiation which is likely associated with episodes of magnetic flux eruptions. The $a_*=0.9$ model shows semi-regular variations with a period of $\sim2000\, GM/c^3$ over the final $\sim10,000\, GM/c^3$ of the simulation, which suggests that magnetic flux eruptions may be an important source of quasi-periodic variability. For the simulated accretion rates, the $a_*=0$ model is spinning up while the $a_*=0.9$ model is spinning down. Spinup-spindown equilibrium of the BH will likely be achieved at $0.5 < a_{*,{\rm{eq}}} < 0.6$, assuming continuous accretion in the MAD state.

We present a Spitzer/Herschel focused survey of the Aquila molecular clouds ($d \sim 436$ pc) as part of the eHOPS (extension of HOPS Out to 500 ParSecs) census of nearby protostars. For every source detected in the Herschel/PACS bands, the eHOPS-Aquila catalog contains 1-850 $\mu$m SEDs assembled from 2MASS, Spitzer, Herschel, WISE, and JCMT/SCUBA-2 data. Using a newly developed set of criteria, we classify objects by their SEDs as protostars, pre-ms sequence stars with disks, and galaxies. A total of 172 protostars are found in Aquila, tightly concentrated in the molecular filaments that thread the clouds. Of these, 72 (42\%) are Class 0 protostars, 53 (31\%) Class I protostars, 43 (25\%) are flat-spectrum protostars, and 4 (2\%) are Class II sources. Ten of the Class 0 protostars are young PACS Bright Red Sources similar to those discovered in Orion. We compare the SEDs to a grid of radiative transfer models to constrain the luminosities, envelope densities, and envelope masses of the protostars. A comparison of the eHOPS-Aquila to the HOPS protostars in Orion finds the protostellar luminosity functions are statistically indistinguishable, the bolometric temperatures/envelope masses of eHOPS-Aquila protostars are shifted to cooler temperatures/higher masses, and the eHOPS-Aquila protostars do not show the decline in luminosity with evolution found in Orion. We briefly discuss whether these differences are due to biases between the samples, diverging star formation histories, or the influence of environment on protostellar evolution.

To investigate the role of magnetic fields in the evolution of the interstellar medium, formation and evolution of molecular clouds, and ultimately the formation of stars, their three-dimensional (3D) magnetic fields must be probed. Observing only one component of magnetic fields (along the line of sight or parallel to the plane of the sky) is insufficient to identify these 3D vectors. In recent years, novel techniques for probing each of these two components and integrating them with additional data (from observations or models), such as Galactic magnetic fields or magnetic field inclination angles, have been developed, in order to infer 3D magnetic fields. We review and discuss these advancements, their applications, and their future direction.

Optical time-domain surveys can unveil and characterize exciting but less-explored non-accreting and/or non-beaming neutron stars (NS) in binaries. Here we report the discovery of such a NS candidate using the LAMOST spectroscopic survey. The candidate, designated LAMOST J112306.9+400736 (hereafter J1123), is in a single-lined spectroscopic binary containing an optically visible M star. The star's large radial velocity variation and ellipsoidal variations indicate a relatively massive unseen companion. Utilizing follow-up spectroscopy from the Palomar 200-inch telescope and high-precision photometry from TESS, we measure a companion mass of $1.24_{-0.03}^{+0.03}~M_{\odot}$. Main-sequence stars with this mass are ruled out, leaving a NS or a massive white dwarf (WD). Although a massive WD cannot be ruled out, the lack of UV excess radiation from the companion supports the NS hypothesis. Deep radio observations with FAST yielded no detections of either pulsed or persistent emission. J1123 is not detected in numerous X-ray and gamma-ray surveys. These non-detections suggest that the NS candidate is not presently accreting and pulsing. Our work exemplifies the capability of discovering compact objects in non-accreting close binaries by synergizing the optical time-domain spectroscopy and high-cadence photometry.

Mechanisms of particle heating are crucial to understanding the shock physics in supernova remnants (SNRs). However, there has been little information on time variabilities of thermalized particles so far. Here, we present a discovery of a gradually-brightening thermal X-ray emission found in Chandra data of Tycho's SNR obtained during 2000--2015. The emission exhibits a knot-like feature (Knot1) with a diameter of $\simeq0.04$~pc located in the northwestern limb, where we also find localized H$\alpha$ filaments in an optical image taken with the Hubble Space Telescope in 2008. The model with the solar abundance reproduces the spectra of Knot1, suggesting that Knot1 originates from interstellar medium; this is the first detection of thermal X-ray emission from swept-up gas found in Tycho's SNR. Our spectral analysis indicates that the electron temperature of Knot1 has increased from $\sim0.30$~keV to $\sim0.69$~keV within the period between 2000 and 2015. These results lead us to ascribe the time-variable emission to a small dense clump recently heated by the forward shock at the location of Knot1. The electron-to-proton temperature ratio immediately downstream the shock ($\beta_{0}\equiv T_e/T_p$) is constrained to be $m_e/m_p\leq\beta_{0}\leq0.15$ to reproduce the data, indicating the collisionless electron heating with efficiency consistent with previous H$\alpha$ observations of Tycho and other SNRs with high shock velocities.

We propose a general model where quintessence couples to electromagnetism via its kinetic term. This novelty generalizes the linear dependence of the gauge kinetic function on $\phi$, commonly adopted in the literature. The interaction naturally induces a time variation of the fine-structure constant that can be formulated within a disformally coupled framework. Through a suitable parametrization of the scalar field and the coupling function, we test the model against observations sensitive to the variation of $\alpha$. We undertake a Bayesian analysis to infer the free parameters with data from Earth based, astrophysical and early Universe experiments. We find that the evolution of $\alpha$ is specific to each cosmological era and slows down at late times when dark energy accelerates the Universe. While the most stringent bound on the interaction is obtained from atomic clocks measurements, the quasars provide a constraint consistent with weak equivalence principle tests. This promising model is to be further tested with upcoming and more precise astrophysical measurements, such as those of the ESPRESSO spectrograph.

This paper follows series of our works on the applicability of various machine learning methods to the morphological galaxy classification (Vavilova et al., 2021, 2022). We exploited the sample of 315776 SDSS DR9 galaxies with absolute stellar magnitudes of -24m<Mr<-19.4m at 0.003<z<0.1 as a target data set for the CNN classifier based on the DenseNet-201. Because it is tightly overlapped with the Galaxy Zoo 2 (GZ2) sample, we use these annotated data as the training data set to classify galaxies into 34 detailed features. In the presence of a pronounced difference of visual parameters between galaxies from the GZ2 training data set and galaxies without known morphological parameters, we applied novel procedures, which allowed us for the first time to get rid of this difference for smaller and fainter SDSS galaxies. We describe in detail the adversarial validation technique as well as how we managed the optimal train-test split of galaxies from the training data set. We have also found optimal galaxy image transformations to increase the classifier generalization ability. It can be considered as another way to improve the human bias for those galaxy images that had a poor vote classification in the GZ project. Such an approach, likely auto-immunization, when the CNN classifier trained on very good images is able to retrain bad images from the same homogeneous sample, can be considered co-planar to other methods of combating the human bias. The accuracy of CNN classifier is in the range of 83.3-99.4 percent depending on 32 features. As a result, for the first time, we assigned the detailed morphological classification for more than 140K low-redshift galaxies, especially at the fainter end. We accentuate on the typical problem points of galaxy CNN image classification from the astronomical point of view. The catalogs will be available through the VizieR.

We analyze Ha or CO rotation curves (RCs) extending out to several galaxy effective radii for 100 massive, large, star-forming disk galaxies (SFGs) across the peak of cosmic galaxy star formation (z~0.6-2.5), more than doubling the previous sample presented by Genzel et al. (2020) and Price et al. (2021). The observations were taken with SINFONI and KMOS integral-field spectrographs at ESO-VLT, LUCI at LBT, NOEMA at IRAM, and ALMA. We fit the major axis kinematics with beam-convolved, forward models of turbulent rotating disks with bulges embedded in dark matter (DM) halos, including the effects of pressure support. The fraction of dark to total matter within the disk effective radius ($R_e ~ 5 kpc$), $f_DM (R_e)=V_{DM}^2 (R_e)/V_{circ}^2 (R_e)$, decreases with redshift: At z~1 (z~2) the median DM fraction is $0.38\pm 0.23$ ($0.27\pm 0.18$), and a third (half) of all galaxies are "maximal" disks with $f_{DM} (R_e)<0.28$. Dark matter fractions correlate inversely with the baryonic surface density, and the low DM fractions require a flattened, or cored, inner DM density distribution. At z~2 there is ~40% less dark matter mass on average within $R_e$ compared to expected values based on cosmological stellar-mass halo-mass relations. The DM deficit is more evident at high star formation rate (SFR) surface densities ($\Sigma_{SFR}>2.5 M_{\odot} yr^{-1} kpc^{-2}$) and galaxies with massive bulges ($M_{bulge}>10^{10} M_{\odot}$). A combination of stellar or active galactic nucleus (AGN) feedback, and/or heating due to dynamical friction, either from satellite accretion or clump migration, may drive the DM from cuspy into cored mass distributions. The observations plausibly indicate an efficient build-up of massive bulges and central black holes at z~2 SFGs.

Relaxation of braided coronal magnetic fields through reconnection is thought to be a source of energy to heat plasma in active region coronal loops. However, observations of active region coronal heating associated with untangling of magnetic braids remain sparse. One reason for this paucity could be the lack of coronal observations with sufficiently high spatial and temporal resolution to capture this process in action. Using new high spatial resolution (250-270 km on the Sun) and high cadence (3-10 s) observations from the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter we observed untangling of small-scale coronal braids in different active regions. The untangling is associated with impulsive heating of the gas in these braided loops. We assess that coronal magnetic braids overlying cooler chromospheric filamentary structures are perhaps more common. Furthermore, our observations show signatures of both spatially coherent and intermittent coronal heating during relaxation of magnetic braids. Our study reveals the operation of both more gentle and impulsive modes of magnetic reconnection in the solar corona.

We investigate the impact of clouds on the atmosphere of GJ~1214b using the radiatively-coupled, phase-equilibrium cloud model {\sc EddySed} coupled to the {\sc Unified Model} general circulation model. We find that, consistent with previous investigations, high metallicity ($100\times$ solar) and clouds with large vertical extents (a sedimentation factor of $f_\mathrm{sed} = 0.1$) are required to best match the observations, although metallicities even higher than those investigated here may be required to improve agreement further. We additionally find that in our case which best matches the observations ($f_\mathrm{sed}=0.1$), the velocity structures change relative to the clear sky case with the formation of a superrotating jet being suppressed, although further investigation is required to understand the cause of the suppression. The increase in cloud extent with $f_\mathrm{sed}$ results in a cooler planet due to a higher albedo, causing the atmosphere to contract. This also results in a reduced day-night contrast seen in the phase curves, although the introduction of cloud still results in a reduction of the phase offset. We additionally investigate the impact the the {\sc Unified Model}'s pseudo-spherical irradiation scheme on the calculation of heating rates, finding that the introduction of nightside shortwave heating results in slower mid-latitude jets compared to the plane parallel irradiation scheme used in previous works. We also consider the impact of a gamma distribution, as opposed to a log-normal distribution, for the distribution of cloud particle radii and find the impact to be relatively minor.

CP2 stars show periodic photometric, spectroscopic, and magnetic variations with the rotational period. They are generally slow rotators, with rotational periods exceeding half a day, except for the late B-type star HD 60431, which has an unusually short rotational period of 0.4755 days. As slow rotation is deemed a necessary criterion for the establishment of chemical peculiarities, this characteristic renders HD 60431 a special object that might offer valuable insight into, and constraints on, the formation and evolution of CP2 stars. Our study aims at analysing the light variability, deriving atmospheric abundances, and determining detailed physical parameters of HD 60431 to confirm its status as the CP2 star with the shortest known rotational period, with special emphasis on the rotational period evolution. Photometric indices and high-resolution spectroscopy were employed to derive physical parameters, evolutionary status, and atmospheric abundances of our target star. A light variability study was carried out using combined sets of photometric data from ground- and space-based facilities. A circularly polarised spectrum was employed to check the presence of a longitudinal magnetic field in the star. With an age of only 10 Myr, HD 60431 is situated close to the zero-age main sequence and a member of the open cluster NGC 2547 in the Vela OB2 complex. We confirm its status as a classical late B-type CP2 star showing strong overabundances of Mg (1.8 dex), Si (1.9 dex), Ca (1.6 dex), Ti (2.2 dex), and Fe (1.8 dex). No conclusive evidence for the presence of a strong magnetic field was found in the available spectroscopic data. The available photometric time series data confirm the short rotational period and indicate a slight secular increase of the rotational period of P' = 7.5(6) ms/yr. HD 60431 is indeed the CP2 star with the shortest known rotational period.

We construct a sample of 644 carbon-enhanced metal-poor (CEMP) stars with abundance analyses based on moderate- to high-resolution spectroscopic studies. Dynamical parameters for these stars are estimated, based on radial velocities, Bayesian parallax-based distance estimates, and proper motions from Gaia EDR3 and DR3, supplemented by additional available information where needed. We apply the HDBSCAN clustering method to the specific energies and actions (E, Jr , J{\phi}, Jz ), obtaining 39 individual Chemo-Dynamically Tagged Groups (CDTGs) of CEMP stars. The stars in the full sample of CDTGs exhibit large and statistically insignificant dispersions in [Fe/H], [C/Fe]c, and [Mg/Fe], when compared to random draws from their parent sample. When the clustering is performed on CEMP stars separated into the morphological groups in the Yoon-Beers Diagram, the Group I (primarily CEMP-s and CEMP-r/s) stars exhibit lower (but still statistically insignificant) dispersions in [Fe/H], and larger (statistically insignificant) dispersions in [C/Fe]c and [Mg/Fe]. In contrast, the Group II (primarily CEMP-no) stars exhibit clear similarities, with very low, highly statistically significant, dispersions in [Fe/H] and [C/Fe]c. These results strongly indicate that Group I CEMP stars received their carbon enhancements from local phenomena, such as mass transfer from a evolved binary companion in regions with extended star-formation histories, while the CDTGs of Group II CEMP stars formed in low-metallicity environments that had already been enriched in carbon, likely from massive rapidly rotating ultra and hyper metal-poor stars and/or supernovae associated with high-mass early generation stars.

We develop a simple iterative scheme to include vertical turbulent mixing and diffusion in ProDiMo thermo-chemical models for protoplanetary discs. The models are carefully checked for convergence toward the time-independent solution of the reaction-diffusion equations, as e.g. used in exoplanet atmosphere models. A series of five T Tauri disc models is presented where we vary the mixing parameter {\alpha} mix from 0 to 0.01 and take into account (a) the radiative transfer feedback of the opacities of icy grains that are mixed upward and (b) the feedback of the changing molecular abundances on the gas temperature structure caused by exothermic reactions and increased line heating/cooling. We see considerable changes of the molecular and ice concentrations in the disc. The most abundant species (H2, CH4, CO, the neutral atoms in higher layers, and the ices in the midplane) are transported both up and down, and at the locations where these abundant chemicals finally decompose, for example by photo processes, the release of reaction products has important consequences for all other molecules. This generally creates a more active chemistry, with a richer mixture of ionised, atomic, molecular and ice species and new chemical pathways that are not relevant in the unmixed case. We discuss the impact on three spectral observations caused by mixing and find that (i) icy grains can reach the observable disc surface where they cause ice absorption and emission features at IR to far-IR wavelengths, (ii) mixing increases the concentrations of certain neutral molecules observable by mid-IR spectroscopy, in particular OH, HCN and C2H2, and (iii) mixing can change the optical appearance of CO in ALMA line images and channel maps, where strong mixing would cause the CO molecules to populate the distant midplane.

The Sun cubE onE (SEE) is a 12U CubeSat mission proposed for a phase A/B study to the Italian Space Agency that will investigate Gamma and X-ray fluxes and ultraviolet (UV) solar emission to support studies in Sun-Earth interaction and Space Weather from LEO. More in detail, SEE's primary goals are to measure the flares emission from soft-X to Gamma ray energy range and to monitor the solar activity in the Fraunhofer Mg II doublet at 280 nm, taking advantage of a full disk imager payload. The Gamma and X-ray fluxes will be studied with unprecedented temporal resolution and with a multi-wavelength approach thanks to the combined use of silicon photodiode and silicon photomultiplier (SiPM) -based detectors. The flare spectrum will be explored from the keV to the MeV range of energies by the same payload, and with a cadence up to 10 kHz and with single-photon detection capabilities to unveil the sources of the solar flares. The energy range covers the same bands used by GOES satellites, which are the standard bands for flare magnitude definition. At the same time SiPM detectors combined with scintillators allow to cover the non-thermal bremsstrahlung emission in the gamma energy range. Given its UV imaging capabilities, SEE will be a key space asset to support detailed studies on solar activity, especially in relation to ultraviolet radiation which strongly interacts with the upper layers of the Earth's atmosphere, and in relation to space safety, included in the field of human space exploration. The main goal for the UV payload is to study the evolution of the solar UV emission in the Mg II band at two different time scales: yearly variations along the solar cycle and transient variations during flare events.

We present the results of studying the accretion disk vs jet power for a large fraction of all the blazars detected by the Fermi Gamma-Ray Space Telescope. The disk power is inferred from the emission line luminosities obtained from published results. As indicators of jet power, we use low frequency radio luminosity from the extended jet, maximum speed of radio knots observed in the VLBA monitoring of the pc-scale jets, kinetic energy of electrons in the jet deduced from the best-fit theoretical models of their spectral energy distribution, and gamma-ray luminosity with and without beaming correction. We obtain a significant correlation in most of those cases. However, we find that the correlations are often driven by the common redshift dependence of the compared quantities. In order to remove the redshift bias and probe the intrinsic correlation between the disk and jet power, we compute the partial correlation coefficient as well as the correlation in small redshift bins, and find that the intrinsic disk-jet correlation is still present but weaker. In the cases, in which the common redshift dependence does not affect the result, we find that blazars do not exhibit high jet power for low disk luminosities while there are both high and low jet power for high disk luminosities. This result indicates that a powerful disk is a necessary but not sufficient condition to produce a powerful jet.

The cosmological recombination radiation (CRR) is one of the guaranteed spectral distortion signals from the early Universe. The CRR photons from hydrogen and helium pre-date the last scattering process and as such allow probing physical phenomena in the pre-recombination era. Here we compute the modifications to the CRR caused by early dark energy models and varying fundamental constants. These new physics examples have seen increased recent activity in connection with the Hubble tension, motivating the exploratory study presented here. The associated CRR responses are spectrally-rich but the level of the signals is small. We forecast the possible sensitivity of future spectrometers to these effects. Our estimates demonstrate that the CRR directly depends to changes in the expansion history and recombination physics during the pre-recombination era. However, futuristic sensitivities are required for spectrometer-only constraints that are competitive with other cosmological probes. Nevertheless, measurements of the CRR can directly reach into phases that otherwise remain inaccessible, highlighting the potential these types of observations could have as a probe of the early Universe. A combination with ${\it Planck}$ data further shows that a synergistic approach is very promising.

We analysed visual observation data of the Tau Herculids collected between 2022 May 28 and June 1. The population index for the entire sample is 2.4. For the pre-peak period we find r=2.57+-0.23, the peak period yields r=2.38+-0.06. The ZHR maximum of the 1995 ejecta from comet Schwassmann-Wachmann3 (SW3) is found at 69.450 deg solar longitude (May 31, 05h04mUT, +-5min) with a ZHR=55+-7, corresponding to a spatial number density ND of approx. 380 meteoroids larger than 10mg in a cube with 1000km edge length. An earlier maximum occurred at 69.207 deg solar longitude (centred May 30, 23h UT) with a ZHR=18+-3 and is tentatively associated with SW3-ejecta from 1892. Effects of the radiant shift due to the large zenith attraction of about 10 deg for the radiant close to the horizon are discussed.

We present a nonlinear model of self-consistent Galactic halo, where the processes of cosmic ray (CR) propagation and excitation/damping of MHD waves are included. The MHD-turbulence, which prevents CR escape from the Galaxy, is entirely generated by the resonant streaming instability. The key mechanism controlling the halo size is the nonlinear Landau (NL) damping, which suppresses the amplitude of MHD fluctuations and, thus, makes the halo larger. The equilibrium turbulence spectrum is determined by a balance of CR excitation and NL damping, which sets the regions of diffusive and advective propagation of CRs. The boundary $z_{cr}(E)$ between the two regions is the halo size, which slowly increases with the energy. For the vertical magnetic field of $\sim 1~\mu G$, we estimate $z_{cr} \sim 1$ kpc for GeV protons. The derived proton spectrum is in a good agreement with observational data.

The Laser Interferometer Space Antenna (LISA) of the European Space Agency (ESA) will be the first low-frequency gravitational-wave observatory orbiting the Sun at 1 AU. The LISA Pathfinder (LPF) mission, aiming at testing of the instruments to be located on board the LISA spacecraft (S/C), hosted, among the others, fluxgate magnetometers and a particle detector as parts of a diagnostics subsystem. These instruments allowed us for the estimate of the magnetic and Coulomb spurious forces acting on the test masses that constitute the mirrors of the interferometer. With these instruments we also had the possibility to study the galactic cosmic-ray short term-term variations as a function of the particle energy and the associated interplanetary disturbances. Platform magnetometers and particle detectors will be also placed on board each LISA S/C. This work reports about an empirical method that allowed us to disentangle the interplanetary and onboard-generated components of the magnetic field by using the LPF magnetometer measurements. Moreover, we estimate the number and fluence of solar energetic particle events expected to be observed with the ESA Next Generation Radiation Monitor during the mission lifetime. An additional cosmic-ray detector, similar to that designed for LPF, in combination with magnetometers, would permit to observe the evolution of recurrent and non-recurrent galactic cosmic-ray variations and associated increases of the interplanetary magnetic field at the transit of high-speed solar wind streams and interplanetary counterparts of coronal mass ejections. The diagnostics subsystem of LISA makes this mission also a natural multi-point observatory for space weather science investigations.

Context: The last few decades has seen numerous studies dedicated to fine structures of type III radio bursts observed in the metric to decametric wavelengths. Majority of explanations of the structured radio emission involve the propagation of electron beam through the strongly inhomogeneous plasma in the low corona. Until now only few studies of single type III bursts with fine structures, observed in the hecto-kilometric wavelengths, were reported. Aims: Herein we report about existence of numerous structured type III radio bursts observed during the STEREO era by all three WAVES instruments on board STEREO A, B, and Wind. The aim of the study is to report, classify structured type III bursts, and present the characteristics of their fine structures. The final goal is to try to understand the physical mechanism responsible for the generation of structured radio emission. Methods: In this study we used data from all available spacecraft, specifically the STEREO and the Wind spacecraft. We employ 1D density models to obtain the speed of the source of type III radio emission, the electron beam. We also perform spectral analysis of the fine structures in order to compare their characteristics with the metric-decametric fine structures. Results: The presented similarities of the type III fine structures in the metric to decametric and interplanetary wavelengths indicate that the physical processes responsible for the generation of structured type III radio bursts could be the same, at the heights, all the way from the low corona to the interplanetary range. We show that the observed structuring and intermittent nature of the type III bursts can be explained by the variation in the level of density fluctuations, at different distances from the Sun.

Evidence is seen for young, fresh surfaces among Near-Earth and Main-Belt asteroids even though space-weathering timescales are shorter than the age of the surfaces. A number of mechanisms have been proposed to refresh asteroid surfaces on short timescales, such as planetary encounters, YORP spinup, thermal degradation, and collisions. Additionally, other factors such as grain size effects have been proposed to explain the existence of these "fresh-looking" spectra. To investigate the role each of these mechanisms may play, we collected a sample of visible and near-infrared spectra of 477 near-Earth and Mars Crosser asteroids with similar sizes and compositions - all with absolute magnitude H > 16 and within the S-complex and having olivine to pyroxene (ol/(ol+opx)) ratios > 0.65. We taxonomically classify these objects in the Q (fresh) and S (weathered) classes. We find four trends in the Q/S ratio: 1) previous work demonstrated the Q/S ratio increases at smaller sizes down to H<16, but we find a sharp increase near H=19 after which the ratio decreases monotonically 2) in agreement with many previous studies, the Q/S ratio increases with decreasing perihelion distance, and we find it is non-zero for larger perihelia greater than 1.2AU, 3) as a new finding our work reveals the Q/S ratio has a sharp, significant peak near 5 degrees orbital inclination, and 4) we confirm previous findings that the Q/S ratio is higher for objects that have the possibility of encounter with Earth and Venus versus those that don't, however this finding cannot be distinguished from the perihelion trend. No single resurfacing mechanism can explain all of these trends, so multiple mechanisms are required. It is likely that a combination of all four resurfacing mechanisms are needed to account for all observational trends.

This study developed an automated identification procedure for compact clouds with broad velocity widths in the spectral line data cubes of highly crowded regions. The procedure was applied to the CO J=3-2 line data, obtained using the James Clerk Maxwell Telescope, to identify 184 high velocity dispersion compact clouds (HVCCs), which is a category of peculiar molecular clouds found in the central molecular zone of our galaxy. A list of HVCCs in the area -1.4{\deg}<l<+2.0{\deg}, -0.25{\deg}<b<+0.25{\deg} was presented with their physical parameters, CO J=3-2/J=1-0 intensity ratios, and morphological classifications. Consequently, the list provides several intriguing sources that may have been driven by encounters with point-like massive objects, local energetic events, or cloud-to-cloud collisions.

Due to the computational cost of calculating a great number of variations of the parameters, detailed radiative models of pulsar wind nebulae (PWNe) do not usually contain fitting algorithms. As a consequence, most of the models in the literature are, in fact, qualitative fits based on visual inspection. This is particularly true when complex, time-dependent models are considered. Motivated by improvements in the computational efficiency of the current PWN models that were obtained in the last years, we here explore the inclusion of automatic fitting algorithms into a fully time-dependent model. Incorporating an efficient fitting tool based on the Nelder-Mead algorithm, we blindly find fitting solutions for the Crab nebula and 3C 58 with a time-dependent radiation model to compute the spectral and dynamical evolution of young and middle-aged PWNe. This inclusion allows us, in addition of more faithfully determining the quality of the fit, to tackle whether there exist degeneracy in the selected PWNe models. We find both for Crab and 3C58, that the fits are well determined, and that no other significantly different set of model parameters is able to cope with experimental data equally well. The code is also able to consider the system's age as a free parameter, recursively determining all other needed magnitudes depending on age accordingly. We use this feature to consider whether a detailed multi-frequency spectra can constrain the nebula age, finding that in fact this is the case for the two PWNe studied.

The process of \acp{PBH} formation would be inevitably accompanied by \acp{SIGW}. This strong correlation between \acp{PBH} and \acp{SIGW} signals could be a promising approach to detecting \acp{PBH} in the upcoming \ac{GW} experiments, such as \ac{LISA}. We investigate the third order \acp{SIGW} during a \ac{RD} era in the case of a monochromatic primordial power spectrum $\mathcal{P}_{\zeta}=A_{\zeta}k_*\delta\left(k-k_*\right)$. For \ac{LISA} observations, the relations between \ac{SNR} and monochromatic primordial power spectrum are studied systematically. It shows that the effects of third order \acp{SIGW} extend the cutoff frequency from $2f_*$ to $3f_*$ and lead to about $200\%$ increase of the \ac{SNR} for frequency band from $10^{-5}$Hz to $1.6\times 10^{-3}$Hz corresponding to \acp{PBH} with mass range $4\times 10^{-12}M_{\odot} \sim 10^{-7}M_{\odot}$. We find that there exists a critical value $A_*=1.76\times 10^{-2}$ for the amplitude of the monochromatic primordial power spectra, such that when $A_{\zeta}>A_*$, the energy density of third order \acp{SIGW} will be larger than the energy density of second order \acp{SIGW}.

Intermittency and anisotropy are two important aspects of plasma turbulence, which the solar wind provides a natural laboratory to investigate. However, their forms and nature are still under debate, making it difficult to achieve a consensus in the theoretical interpretation. Here, we perform higher-order statistics for the observations in the fast solar wind at 1.48 au obtained by Ulysses and in the slow solar wind at 0.17 au obtained by Parker Solar Probe (PSP). We find that two subranges clearly exist in the inertial range and they present distinct features with regard to the intermittency and anisotropy. The subrange 1 with smaller scale has a multifractal scaling with the second index $\xi(2) \sim 2/3$ and the subrange 2 with larger scale is also multifractal but with $\xi(2) \sim 1/2$. The break between two subranges locates at the same spatial scale for both Ulysses and PSP observations. Subrange 1 is multifractal in the direction perpendicular to the local magnetic field with $\xi_{\perp}(2) \sim 2/3$ and seems to be monoscaling in the parallel direction with $\xi_{\parallel}(2) \sim 1$. Subrange 2 is multifractal in both parallel and perpendicular directions with $\xi_{\perp}(2) \sim 1/2$ and $\xi_{\parallel}(2) \sim 2/3$. Both subrange 1 and subrange 2 present power and wavevector anisotropies. The distinct features of two subranges suggest that a transition from weak to strong turbulence may occur and the spatial scale of the break may not evolve with the solar wind expansion. These new results update our knowledge of the inertial range and provide strong observational constraints on the understanding of intermittency and anisotropy in solar wind turbulence.

We study the impact of rotation on the multimessenger signals of core-collapse supernovae (CCSNe) with the occurrence of a first-order hadron-quark phase transition (HQPT). We simulate CCSNe with the \texttt{FLASH} code starting from a 20~$M_\odot$ progenitor with different rotation rates, and using the RDF equation of state from \textit{Bastian} 2021 that prescribes the HQPT. Rotation is found to delay the onset of the HQPT and the resulting dynamical collapse of the protocompact star (PCS) due to the centrifugal support. All models with the HQPT experience a second bounce shock which leads to a successful explosion. The oblate PCS as deformed by rotation gives rise to strong gravitational-wave (GW) emission around the second bounce with a peak amplitude larger by a factor of $\sim10$ than that around the first bounce. The breakout of the second bounce shock at the neutrinosphere produces a $\bar{\nu}_e$-rich neutrino burst with a luminosity of serveral 10$^{53}$~erg~s$^{-1}$. In rapidly rotating models the PCS pulsation following the second bounce generates oscillations in the neutrino signal after the burst. In the fastest rotating model with the HQPT, a clear correlation is found between the oscillations in the GW and neutrino signals immediately after the second bounce. In addition, the HQPT-induced collapse leads to a jump in the ratio of rotational kinetic energy to gravitational energy ($\beta$) of the PCS, for which persistent GW emission may arise due to secular nonaxisymmetric instabilities.

We report the discovery of six ultra-faint Milky Way satellites discovered through matched-filter searches conducted using Dark Energy Camera (DECam) data processed as part of the second data release of the DECam Local Volume Exploration (DELVE) survey. Leveraging deep Gemini/GMOS-N imaging (for four candidates) as well as follow-up DECam imaging (for two candidates), we characterize the morphologies and stellar populations of these systems. We find that these candidates all share faint absolute magnitudes ($M_{V} \geq -3.2$ mag) and old, metal-poor stellar populations ($\tau > 10$ Gyr, [Fe/H] $< -1.4$ dex). Three of these systems are more extended ($r_{1/2} > 15$ pc), while the other three are compact ($r_{1/2} < 10$ pc). From these properties, we infer that the former three systems (Bo\"{o}tes V, Leo Minor I, and Virgo II) are consistent with ultra-faint dwarf galaxy classifications, whereas the latter three (DELVE 3, DELVE 4, and DELVE 5) are likely ultra-faint star clusters. Using data from the Gaia satellite, we confidently measure the proper motion of Bo\"{o}tes V, Leo Minor I, and DELVE 4, and tentatively detect a proper motion signal from DELVE 3 and DELVE 5; no signal is detected for Virgo II. We use these measurements to explore possible associations between the newly-discovered systems and the Sagittarius dwarf spheroidal, the Magellanic Clouds, and the Vast Polar Structure, finding several plausible associations. Our results offer a preview of the numerous ultra-faint stellar systems that will soon be discovered by the Vera C. Rubin Observatory and highlight the challenges of classifying the faintest stellar systems.

We present a search for Galactic transient gamma-ray sources using 13 years of the Fermi Large Area Telescope data. The search is based on a recently developed variable-size sliding-time-window (VSSTW) analysis and aimed at studying variable gamma-ray emission from binary systems, including novae, gamma-ray binaries, and microquasars. Compared to the previous search for transient sources at random positions in the sky, we included gamma rays with energies down to 500 MeV, increased a number of test positions, and extended the data set by adding data collected between from February 2020 to July 2021. These refinements allowed us to detect an additional three novae, V1324 Sco, V5855 Sgr, V357 Mus, and one gamma-ray binary, PSR B1259-63, with the VSSTW method. Our search revealed a gamma-ray flare from the microquasar, Cygnus X-3, occurred in 2020. When applied to equal quarters of the data, the analysis provided us with detections of repeating signals from PSR B1259-63, LS I +61 303, PSR J2021+4026, and Cygnus X-3. While the Cygnus X-3 was bright in gamma rays in mid-2020, it was in a soft X-ray state and we found that its gamma-ray emission was modulated with the orbital period.

We develop a new relativistic radiation hydrodynamics code based on the Monte-Carlo algorithm. In this code, we implement a new scheme to achieve the second-order accuracy in time in the limit of a large packet number for solving the interaction between matter and radiation. This higher-order time integration scheme is implemented in the manner to guarantee the energy-momentum conservation to the precision of the geodesic integrator. The spatial dependence of radiative processes, such as the packet propagation, emission, absorption, and scattering, are also taken into account up to the second-order accuracy. We validate our code by solving various test-problems following the previous studies; one-zone thermalization, dynamical diffusion, radiation dragging, radiation mediated shock-tube, shock-tube in the optically thick limit, and Eddington limit problems. We show that our code reproduces physically appropriate results with reasonable accuracy and also demonstrate that the second-order accuracy in time and space is indeed achieved with our implementation for one-zone and one-dimensional problems.

Interplanetary scintillation (IPS) is a useful tool for detecting coronal mass ejections (CMEs) throughout interplanetary space. Global magnetohydrodynamic (MHD) simulations of the heliosphere, which are usually used to predict the arrival and geo-effectiveness of CMEs, can be improved using IPS data. In this study, we demonstrate an MHD simulation that includes IPS data from multiple stations to improve CME modelling. The CMEs, which occurred on 09-10 September 2017, were observed over the period 10-12 September 2017 using the Low-Frequency Array (LOFAR) and IPS array of the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, as they tracked through the inner heliosphere. We simulated CME propagation using a global MHD simulation, SUSANOO-CME, in which CMEs were modeled as spheromaks, and the IPS data were synthesised from the simulation results. The MHD simulation suggests that the CMEs merged in interplanetary space, forming complicated IPS g-level distributions in the sky map. We found that the MHD simulation that best fits both LOFAR and ISEE data provided a better reconstruction of the CMEs and a better forecast of their arrival at Earth than from measurements when these simulations were fit from the ISEE site alone. More IPS data observed from multiple stations at different local times in this study can help reconstruct the global structure of the CME, thus improving and evaluating the CME modelling.

LiteBIRD is a space-borne experiment dedicated to detecting large-scale $B$-mode anisotropies in the linear polarization of the Cosmic Microwave Background (CMB) predicted by the theory of inflation. It is planned to be launched in the late 2020s to the second Lagrange point (L2) of the Sun-Earth system. LiteBIRD will map the sky in 15 frequency bands. In comparison to $\it{Planck}$ HFI, the previous low-temperature bolometer-based satellite for CMB observations, the number of detector has increased by two orders of magnitude, up to $\sim$5000 detectors in total. The data rate is 19 Hz from each detector. The bandpass to the ground is limited to 10 Mbps using the X-band for a few hours per day. These require the data to be compressed by more than 50 %. The exact value depends on how much information entropy is contained in the real data. We have thus evaluated the compression by simulating the time-ordered data of polarization sensitive bolometers. The foreground emission, detector noise, cosmic ray glitches, leakage from the CMB intensity to polarization, etc. are simulated. We investigated several algorithms and demonstrated that the required compression ratio can be achieved by some of them. We describe the details of this evaluation and propose algorithms that can be employed in the on-board digital electronics of LiteBIRD.

Using current technology, gravitational microlensing is the only method that can measure planet masses over the full parameter space of planet and stellar-host masses and at a broad range of planet-host separations. I present a comprehensive program to transform the $\sim 150$ planet/host mass ratio measurements from the first 6 full seasons of the KMTNet survey into planet mass measurements via late-time adaptive optics (AO) imaging on 30m-class telescopes. This program will enable measurements of the overall planet mass function, the planet frequency as a function of Galactic environment and the planet mass functions within different environments. I analyze a broad range of discrete and continuous degeneracies as well as various false positives and false negatives, and I present a variety of methods to resolve these. I analyze the propagation from measurement uncertainties to mass and distance errors and show that these present the greatest difficulties for host masses $0.13\lesssim(M/M_\odot)\lesssim 0.4$, i.e., fully convective stars supported by the ideal gas law, and for very nearby hosts. While work can begin later this decade using AO on current telescopes, of order 90% of the target sample must await 30m-class AO. I present extensive tables with information that is useful to plan observations of more than 100 of these planets and provide additional notes for a majority of these. Applying the same approach to two earlier surveys with 6 and 8 planets, respectively, I find that 11 of these 14 planets already have mass measurements by a variety of techniques. These provide suggestive evidence that planet frequency may be higher for nearby stars, $D_L\lesssim 4$ kpc compared to those in or near the Galactic bulge. Finally, I analyze the prospects for making the planet mass-function measurement for the case that current astronomical capabilities are seriously degraded.

Determining the habitability and interpreting atmospheric spectra of exoplanets requires understanding their atmospheric physics and chemistry. We use a 3-D Coupled Climate-Chemistry Model, the Met Office Unified Model with the UK Chemistry and Aerosols framework, to study the emergence of lightning and its chemical impact on tidally-locked Earth-like exoplanets. We simulate the atmosphere of Proxima Centauri b orbiting in the Habitable Zone of its M-dwarf star, but the results apply to similar M-dwarf orbiting planets. Our chemical network includes the Chapman ozone reactions and hydrogen oxide (HO$_{\mathrm{x}}$=H+OH+HO$_2$) and nitrogen oxide (NO$_{\mathrm{x}}$=NO+NO$_2$) catalytic cycles. We find that photochemistry driven by stellar radiation (177-850 nm) supports a global ozone layer between 20-50 km. We parameterise lightning flashes as a function of cloud-top height and the resulting production of nitric oxide (NO) from the thermal decomposition of N$_2$ and O$_2$. Rapid dayside convection over and around the substellar point results in lightning flash rates of up to 0.16 flashes km$^{-2}$yr$^{-1}$, enriching the dayside atmosphere below altitudes of 20 km in NO$_{\mathrm{x}}$. Changes in dayside ozone are determined mainly by UV irradiance and the HO$_{\mathrm{x}}$ catalytic cycle. ~45% of the planetary dayside surface remains at habitable temperatures (T$_{\mathrm{surf}}$>273.15 K) and the ozone layer reduces surface UV radiation levels to 15%. Dayside-nightside thermal gradients result in strong winds that subsequently advect NO$_{\mathrm{x}}$ towards the nightside, where the absence of photochemistry allows NO$_{\mathrm{x}}$ chemistry to involve reservoir species. Our study also emphasizes the need for accurate UV stellar spectra to understand the atmospheric chemistry of exoplanets.

We report the identification of the unusual emission-line stellar-like object in the nearby low-metallicity (Z ~ 0.1Zsun) dwarf galaxy NGC 4068. Our observations performed with long-slit spectrograph and Fabry-Perot interferometer demonstrate high velocity dispersion in Ha line, presence of HeII4686A line and peculiarly low [SII]/[NII] fluxes ratio for this object. From observational data, we derived that the object represents a single star of high bolometric luminosity L~1.5*10^6 Lsun surrounded by an expanding nebula with kinematical age of t ~ 0.5Myr. The nebula exhibits significant nitrogen overabundance (log(N/O) ~ -0.05, that is by ~1.4dex higher than expected for low-metallicity galaxies). We suggested that this is a massive blue supergiant (BSG) or Wolf-Rayet (WR) star surrounded by its ejecta interacting with the interstellar medium. We calculated the models of the nebula using CLOUDY photoionization code, applying CMFGEN-modelled BSG and WR stars as ionisation sources. We found a best agreement between the modelled and observed spectra for the model assuming ionization by low-metallicity WR star of mass M*~80Msun, ionizing the nebula through the strong wind and enriching the interstellar medium with nitrogen.

Some dwarf galaxies are within the Mondian regime at all radii, i.e., the gravitational acceleration provided by the observed baryons is always below the threshold of $g_\dag\simeq 1.2\times 10^{-10}\,{\rm m\,s^{-2}}$. These dwarf galaxies often show cores, in the sense that assuming Newton's gravity to explain their rotation curves, the total density profile $\rho(r)$ presents a central plateau or {\em core} ($d\log \rho/d\log r\rightarrow 0$ when $r\rightarrow 0$). Here we show that under MOND gravity, the existence of this core implies a baryon content whose density $g_{\rm bar}$ must decrease toward the center of the gravitational potential ($g_{\rm bar}\rightarrow 0$ when $r\rightarrow 0$). Such drop of baryons toward the central region is neither observed nor appears in numerical simulations of galaxy formation following MOND gravity. We analyze the problem posed for MOND as well as possible workarounds.

We present a study of eclipsing binary J064726.39+223431.6 using spectra from the LAMOST-MRS and TESS photometry. We use full-spectrum fitting to derive radial velocities and spectral parameters: ${T_{\rm eff}}_{A,B}=6177,\,5820$ K, $v \sin{i}_{A,B}=59,\,50~\kms$ and ${\rm [Fe/H]}_{A,B}=-0.19$ dex. The orbital solution and light curve analysis suggest that it is a close pair of fast rotating stars on circular orbit. We measure their masses to be $M_{A,B}=1.307\pm0.007,\, 1.129\pm0.005\,M_\odot$ and their radii to be $R_{A,B}=1.405\pm0.052,\, 1.219\pm0.060\,R_\odot$ resulting in surface gravities of $\log{g}_{A,B}=4.259\pm0.033,\,4.319\pm0.042$ (cgs). Theoretical models cannot match all of these properties, predicting significantly higher ${T_{\rm eff}}$ for a given metallicity. Derived age of the system 1.56 Gyr indicates that both components are younger than Sun. J064726.39+223431.6 is a good candidate for high-resolution spectroscopic analyses.

We investigated a cosmological model that allows a momentum transfer between dark matter and dark energy. The interaction in the dark sector mainly affects the behaviour of perturbations on small scales while the background evolution matches the $w$CDM solution. As a result of the momentum transfer, these kinds of models help alleviating the $\sigma_8$ discrepancy in the standard model, but do not resolve the so-called $H_0$ tension. We confirm that this is indeed the case by computing cosmological constraints. While our analysis tends to favour $\sigma_8$ values lower than in $\Lambda$CDM, we do not find evidence for a non-vanishing momentum transfer in the dark sector. Since upcoming galaxy surveys will deliver information on scales and red-shift relevant for testing models allowing momentum transfer in the dark sector, we also carried out forecasts using different survey configurations. We assessed the relevance of neglecting lensing convergence $\kappa$ when modelling the angular power spectrum of number counts fluctuations $C_\ell^{\rm ij}(z,z')$. We found that not including $\kappa$ in analyses leads to biased constraints ($\approx 1-5\,\sigma$) of cosmological parameters even when including information from other experiments. Incorrectly modelling $C_\ell^{\rm ij}(z,z')$ might lead to spurious detection of neutrino masses and exacerbate discrepancies in $H_0$ and $\sigma_8$.

Mapping the average AGN luminosity across galaxy populations and over time encapsulates important clues on the interplay between supermassive black hole (SMBH) and galaxy growth. This paper presents the demography, mean power and cosmic evolution of radio AGN across star-forming galaxies (SFGs) of different stellar masses (${M_{*}}$). We exploit deep VLA-COSMOS 3 GHz data to build the rest-frame 1.4 GHz AGN luminosity functions at 0.1$\leq$$z$$\leq$4.5 hosted in SFGs. Splitting the AGN luminosity function into different ${M_{*}}$ bins reveals that, at all redshifts, radio AGN are both more frequent and more luminous in higher ${M_*}$ than in lower ${M_*}$ galaxies. The cumulative kinetic luminosity density exerted by radio AGN in SFGs peaks at $z$$\sim$2, and it is mostly driven by galaxies with 10.5$\leq$$\log$(${M_{*}}$/${M_{\odot}}$)$<$11. Averaging the cumulative radio AGN activity across all SFGs at each (${M_{*}}$,$z$) results in a "radio-AGN main sequence" that links the time-averaged radio-AGN power $\langle$$L_{1.4}^{{AGN}}$$\rangle$ and galaxy stellar mass, in the form: $\log$$\langle$[$L_{1.4}^{{AGN}}$/ W Hz$^{-1}]\rangle$ = (20.97$\pm$0.16) + (2.51$\pm$0.34)$\cdot$$\log$(1+$z$) + (1.41$\pm$0.09)$\cdot$($\log$[${M_{*}}$/${M_{\odot}}$] -10). The super-linear dependence on ${M_{*}}$, at fixed redshift, suggests enhanced radio-AGN activity in more massive SFGs, as compared to star formation. We ascribe this enhancement to both a higher radio AGN duty cycle and a brighter radio-AGN phase in more massive SFGs. A remarkably consistent ${M_{*}}$ dependence is seen for the evolving X-ray AGN population in SFGs. This similarity is interpreted as possibly driven by secular cold gas accretion fueling both radio and X-ray AGN activity in a similar fashion over the galaxy's lifetime.

Light curves of solar-like stars are known to show highly irregular variability. As a consequence, standard frequency analysis methods often fail to detect the correct rotation period. Recently, Shapiro et al. (2020) showed that the periods of such stars could still be measured by considering the Gradient of the Power Spectrum (GPS) instead of the power spectrum itself. In this study, the GPS method is applied to model light curves of solar-like stars covering all possible inclination angles and a large range of metallicities and observational noise levels. The model parameters are chosen such that they resemble those of many stars in the Kepler field. We show that the GPS method is able to detect the correct rotation period in 40% of all considered cases, which is more than ten times higher than the detection rate of standard techniques. Thus, we conclude that the GPS method is ideally suited to measure periods of those Kepler stars lacking such a measurement so far. We also show that the GPS method is significantly superior to auto-correlation methods when starspot lifetimes are shorter than a few rotation periods. GPS begins to yield rotation periods that are too short when dominant spot lifetimes are shorter than one rotation period. We conclude that new methods are generally needed to reliably detect rotation periods from sufficiently aperiodic time series -- these periods will otherwise remain undetected.

We present an analysis of archival Spitzer InfraRed Spectrograph (IRS) observations of the recurrent nova RS Ophiuchi obtained on several occasions, beginning about 7 months after the outburst in 2006. These data show atomic emission lines, absorption bands due to photospheric SiO, and the well known silicate dust features at $9.7\,\mu$m and $18\,\mu$m. The dust emission, arising in the wind of the secondary star, is fitted by Dusty models for mass-loss rates in the range $1.0-1.7\times10^{-7}$M$_{\odot}$yr$^{-1}$. The silicate features are similar in profile to those seen in circumstellar environments of isolated late-type stars and some dusty symbiotic binaries, although the longer wavelength feature peaks at $17\,\mu$m,, instead of the usual $18\,\mu$m, indicating peculiar grain properties. The dust features are variable, appearing stronger in 2006-2007 during outburst than in 2008-2009 when the system was in the quiescent state. This variability is attributed to changes in the ultraviolet output and the reformation of the accretion disk, although a decline in the mass-loss rate of the red giant secondary star could also play a role. Further observations, in the aftermath of the 2021 eruption, could provide a definitive conclusion.

One of the major goals of future cosmic microwave background (CMB) $B$-mode polarization experiments is the detection of primordial gravitational waves through an unbiased measurement of the tensor-to-scalar ratio $r$. Robust detection of this signal will require mitigating all possible contamination to the $B$-mode polarization from astrophysical origins. One such extragalactic contamination arises from the patchiness in the electron density during the reionization epoch. Along with the signature on CMB polarization, the patchy reionization can source secondary anisotropies on the CMB temperature through the kinetic Sunyaev-Zeldovich (kSZ) effect. To study this foreground impact, we use a physically motivated model of reionization to evaluate its contribution to the CMB $B$-mode polarization and temperature anisotropies for upcoming CMB missions. We show that the value of $r$ can bias towards a higher value if the secondary contribution from reionization is neglected. However, combining small-scale kSZ signal, large-scale $E$-mode polarization, and $B$-mode polarization measurements, we can put constraints on the patchiness in electron density during reionization and can mitigate its impact on the value of $r$. CMB missions such as CMB-S4 and PICO may experience a bias of $>0.17\sigma$ which can go as high as $\sim 0.73\sigma$ for extreme reionization models allowed by the Planck and SPT CMB measurements. As future experiments target to measure $r$ at $5\sigma$, this is likely to affect the measurement significance and hence possibly affect the claim of detection of $r$, if not mitigated properly by using joint estimations of different reionization observables.

The stability of mass transfer is critical in determining pathways towards various kinds of compact binaries, such as compact main-sequence white-dwarf binaries, and transients, such as double white-dwarf mergers and luminous red novae. Despite its importance, only very few systematic studies of the stability of mass transfer exist. Using the 1D stellar evolution code MESA, we study the behaviour of mass-losing post-main-sequence donor stars with masses between $1 M_{\odot}$ and $8 M_{\odot}$ in binaries, without assuming that the donor star responds to mass loss adiabatically . We treat the accretor as a point mass, which we do not evolve, and assume the mass transfer is conservative. We find that the criterion that best predicts the onset of runaway mass transfer is based on the transition to an effectively adiabatic donor response to mass loss. We find that the critical mass ratio $q_{\rm qad} \sim 0.25$ for stars crossing the Hertzsprung gap, while for convective giants $q_{\rm qad}$ decreases from $\sim 1$ at the base of the RGB to $\sim 0.1$ at the the onset of thermal pulses on the AGB. An effectively adiabatic response of the donor star only occurs at a very high critical mass-transfer rate due to the short local thermal timescale in the outermost layers of a red giant. For $q > q_{\rm qad}$ mass transfer is self-regulated, but for evolved giants the resulting mass-transfer rates can be so high that the evolution becomes dynamical and/or the donor can overflow its outer lobe. Our results indicate that mass transfer is stable for a wider range of binary parameter space than typically assumed in rapid binary population synthesis and found in recent similar studies. Moreover, we find a systematic dependence of the critical mass ratio on the donor star mass and radius which may have significant consequences for predictions of post-mass-transfer populations.

We analyzed the archival data of the $^{13}\mathrm{CO}$ and $\mathrm{C}^{18}\mathrm{O}$ $J=3-2$ emission lines in the protoplanetary disk around MWC 758 obtained with the Atacama Large Millimeter/submillimeter Array to discuss possible planet-disk interaction and non-Keplerian motion in the disk. We performed fitting of a Keplerian disk model to the observational data and measured the velocity deviations from the Keplerian rotation. We found significant velocity deviations around the inner cavity in the MWC 758 disk. We examined several possibilities that may cause the velocity deviations, such as pressure gradient, height of the emitting layer, infall motion, inner warp, and eccentricity in the disk. We found that the combination of an eccentric orbital motion with eccentricity of $0.1\pm0.04$ at the radius of the inner cavity and an infalling flow best explains the observed velocity deviations. Our kinematically constrained eccentricity of the gas orbital motion close to the inner cavity is consistent with the eccentricity of the dust ring around the inner cavity measured in the submillimeter continuum emission. Our results hint at strong dust-gas coupling around the inner cavity and presence of a gas giant planet inside the inner cavity in the MWC 758 disk.

We present the results of the analysis of the photometric data collected in long and short-cadence mode by the Transiting Exoplanet Survey Satellite (TESS) for GJ 504, a well studied planet-hosting solar-like star, whose fundamental parameters have been largely debated during the last decade. Several attempts have been made by the present authors to isolate the oscillatory properties expected on this main-sequence star, but we did not find any presence of solar-like pulsations. The suppression of the amplitude of the acoustic modes can be explained by the high level of magnetic activity revealed for this target, not only by the study of the photometric light-curve, but also by the analysis of three decades available of Mount Wilson spectroscopic data. In particular, our measurements of the stellar rotational period Prot=3.4 d and of the main principal magnetic cycle of 12 a confirm previous findings and allow us to locate this star in the early main sequence phase of its evolution during which the chromospheric activity is dominated by the superposition of several cycles before the transition to the phase of the magnetic-braking shutdown with the subsequent decrease of the magnetic activity.

We extend previous ab initio calculations of lanthanide opacities (Fontes et al., 2020, MNRAS, 493, 4143) to include a complete set of actinide opacities for use in the modeling of kilonova light curves and spectra. Detailed, fine-structure line features are generated using the configuration-interaction approach. These actinide opacities display similar trends to those observed for lanthanide opacities, such as the lighter actinides producing higher opacity than the heavier ones for relevant conditions in the dynamical ejecta. A line-binned treatment is employed to pre-compute opacity tables for 14 actinide elements $(89 \le Z \le 102)$ over a grid of relevant temperatures and densities. These tabular opacities will be made publicly available for general usage in kilonova modeling. We demonstrate the usefulness of these opacities in kilonova simulations by exploring the sensitivity of light curves and spectra to different actinide abundance distributions that are predicted by different nuclear theories, as well as to different choices of ejecta mass and velocity. We find very little sensitivity to the two considered distributions, indicating that opacities for actinides with $Z \ge 99$ do not contribute strongly. On the other hand, a single actinide element, protactinium, is found to produce faint spectral features in the far infrared at late times (5-7 days post merger). More generally, we find that the choice of ejecta mass and velocity have the most significant effect on KN emission for this study.

The recurrent nova and symbiotic binary RS Oph erupted again in August 2021 for its eighth known outburst. As part of a multi-epoch and frequency campaign, we observed RS Oph 34 days after the outburst at 5 GHz with the European VLBI Network (EVN). The radio image is elongated over the east-west direction for a total extension of about 90 mas (or about 240 AU at the Gaia DR3 distance d=2.68 [-0.15/+0.17] kpc), and shows a bright and compact central component coincident with the Gaia astrometric position, and two lobes east and west of it, expanding perpendicular to the orbital plane. By comparing with the evolution of emission-line profiles on optical spectra, we found the leading edge of the lobes to be expanding at 7550 km/s, and i=54 deg as the orbital inclination of the binary. The 2021 radio structure is remarkably similar to that observed following the 2006 eruption. The obscuring role of the density enhancement on the orbital plane (DEOP) is discussed in connection to the time-dependent visibility of the receding lobe in the background to the DEOP, and the origin of the triple-peaked profiles is traced to the ring structure formed by the nova ejecta impacting the DEOP.

MWC 297 is a young, early-type star driving an ionized outflow and surrounded by warm, entrained dust. Previous analyses of near- and mid-IR interferometric images suggest that the emission at these wavelengths arises from a compact accretion disk with a moderate ($i < 40$ degrees) inclination. We have obtained 5-40 micron images of MWC 297 with FORCAST on SOFIA, as well as near-infrared spectra acquired with SpeX on the IRTF and radio data obtained with the VLA and BIMA, and supplemented these with archival data from Herschel/PACS and SPIRE. The FORCAST images, combined with the VLA data, indicate that the outflow lobes are aligned nearly north-south and are well separated. Simple geometrical modeling of the FORCAST images suggests that the disk driving the outflow has an inclination of $55\pm 5$ degrees, in disagreement with the results of the interferometric analyses. Analysis of the SpeX data, with a wind model, suggests the the mass loss rate is on the order of $6.0 \pm ^{3.7}_{1.7} \times 10^{-7} M_\odot ~\mathrm{yr}^{-1}$ and the extinction to the source is $A_V \sim 8.1 \pm^{2.5}_{1.5}$ mag. We have combined our data with values from the literature to generate the spectral energy distribution of the source from $0.35~ \mu$m to $6$ cm and estimate the total luminosity. We find the total luminosity to be about $7900 ~ L_\odot$, if we include emission from an extended region around the star, only slightly below that expected for a B1.5V star. The reddening must be produced by dust along the line of sight, but distant from the star.

We use a particular machine learning approach, called the genetic algorithms (GA), in order to place constraints on deviations from general relativity (GR) via a possible evolution of Newton's constant $\mu\equiv G_\mathrm{eff}/G_\mathrm{N}$ and of the dark energy anisotropic stress $\eta$, both defined to be equal to one in GR. Specifically, we use a plethora of background and linear-order perturbations data, such as type Ia supernovae, baryon acoustic oscillations, cosmic chronometers, redshift space distortions and $E_g$ data. We find that although the GA is affected by the lower quality of the currently available data, especially from the $E_g$ data, the reconstruction of Newton's constant is consistent with both a constant value and with unity within the errors. On the other hand, the anisotropic stress deviates strongly from unity due to the sparsity and the systematics of the $E_g$ data. Finally, we also create synthetic data based on an LSST-like survey and forecast the limits of any possible detection of deviations from GR. In particular we use two fiducial models, namely the cosmological constant model $\Lambda$CDM and a model with an evolving Newton's constant, and we find that the GA reconstructions of $\mu(z)$ and $\eta(z)$ are in most cases constrained to within a few percent of the fiducial models, thus demonstrating the utility of the GA reconstruction approach.

The velocity of the Sun with respect to the cosmic microwave background (CMB) can be extracted from the CMB dipole, provided its intrinsic dipole is assumed to be small in comparison. This interpretation is consistent, within fairly large error bars, with the measurement of the correlations between neighboring CMB multipoles induced by the velocity of the observer, which effectively breaks isotropy. In contrast, the source number count dipole was reported to privilege a velocity of the observer with an amplitude which is about twice as large as the one extracted from the entirely kinematic interpretation of the CMB dipole, with error bars which indicate a more and more significant tension. In this work, we study the effect of the peculiar velocity of the observer on correlations of nearby multipoles in the source number counts. We provide an unbiased estimator for the kinetic dipole amplitude, which is proportional to the peculiar velocity of the observer and we compute the expected signal to noise ratio. Near future experiments can achieve better than 5$\%$ constraints on the velocity of the Sun with our estimator.

We present a study of chemistry toward 294 dense cores in 12 molecular clumps using the data obtained from the ALMA Survey of 70 $\mu \rm m$ dark High-mass clumps in Early Stages (ASHES). We identified 97 protostellar cores and 197 prestellar core candidates based on the detection of outflows and molecular transitions of high upper energy levels ($E_{u}/k > 45$ K). The detection rate of the N$_{2}$D$^{+}$ emission toward the protostellar cores is 38%, which is higher than 9% for the prestellar cores, indicating that N$_{2}$D$^{+}$ does not exclusively trace prestellar cores. The detection rates of the DCO$^{+}$ emission are 35% for the prestellar cores and 49% for the protostellar cores, which are higher than those of N$_{2}$D$^{+}$, implying that DCO$^{+}$ appears more frequently than N$_{2}$D$^{+}$ in both prestellar and protostellar cores. Both N$_{2}$D$^{+}$ and DCO$^{+}$ abundances appear to decrease from the prestellar to protostellar stage. The DCN, C$_{2}$D and $^{13}$CS emission lines are rarely seen in the dense cores of early evolutionary phases. The detection rate of the H$_{2}$CO emission toward dense cores is 52%, three times higher than that of CH$_{3}$OH (17%). In addition, the H$_{2}$CO detection rate, abundance, line intensities, and line widths increase with the core evolutionary status, suggesting that the H$_{2}$CO line emission is sensitive to protostellar activity.

We report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, studied previously with joint fits to NICER and XMM data by Riley et al. 2021 and Miller et al. 2021. We perform a similar Bayesian estimation for the pulse-profile model parameters, except that instead of fitting simultaneously the XMM data, we use the best available NICER background estimates to constrain the number of photons detected from the source. This approach eliminates any potential issues in the cross-calibration between these two instruments, providing thus an independent check of the robustness of the analysis. The obtained neutron star parameter constraints are compatible with the already published results, with a slight dependence on how conservative the imposed background limits are. A tighter lower limit causes the inferred radius to increase, and a tighter upper limit causes it to decrease. We also extend the study of the inferred emission geometry to examine the degree of deviation from antipodality of the hot regions. We show that there is a significant offset to an antipodal spot configuration, mainly due to the non-half-cycle azimuthal separation of the two emitting spots. The offset angle from the antipode is inferred to be above 25 degrees with 84 % probability. This seems to exclude a centered-dipolar magnetic field in PSR J0740+6620.

The merging system SIT 45 (UGC 12589) is an unusual isolated galaxy triplet, consisting of three merging late-type galaxies, out of 315 systems in the SIT (SDSS-based catalogue of Isolated Triplets). The main aims of this work are to study its dynamical evolution and star formation history (SFH), as well as its dependence on its local and large-scale environment. To study its dynamics, parameters such as the velocity dispersion ($\sigma_{v}$), the harmonic radius ($R_{H}$), the crossing time ($H_0t_c$), and the virial mass ($M_{vir}$), along with the compactness of the triplet ($S$) were considered. To constrain the SFH, we used CIGALE to fit its observed spectral energy distribution using multi-wavelength data from the ultraviolet to the infrared. According to its SFH, SIT 45 presents star-formation, where the galaxies also present recent ($\sim $200 Myr) star-formation increase, indicating that this activity may have been triggered by the interaction. Its dynamical configuration suggests that the system is highly evolved in comparison to the SIT. However this is not expected for systems composed of star-forming late-type galaxies, based on observations in compact groups. We conclude that SIT 45 is a system of three interacting galaxies that are evolving within the same dark matter halo, where its compact configuration is a consequence of the on-going interaction, rather than due to a long-term evolution (as suggested from its $H_0t_c$ value). We consider two scenarios for the present configuration of the triplet, one where one of the members is a tidal galaxy, and another where this galaxy arrives to the system after the interaction. Both scenarios need further exploration. The isolated triplet SIT 45 is therefore an ideal system to study short timescale mechanisms ($\sim 10^8$ years), such as starbursts triggered by interactions which are more frequent at higher redshift.

We present an updated data-analysis comparison of the most recent observations of the Cosmic Microwave Background temperature anisotropies and polarization angular power spectra released by four different experiments: the Planck satellite on one side, and the Atacama Cosmology Telescope (ACTPol) and the South Pole Telescope (SPT-3G), combined with the WMAP satellite 9-years observation data in order to be "Planck-independent" on the other side. We investigate in a systematic way 8 extended cosmological models that differ from the baseline $\Lambda$CDM case by the inclusion of many different combinations of additional degrees of freedom. Our analysis provides several hints for anomalies in the CMB angular power spectra in tension with the standard cosmological model. This indicates that either significant unaccounted-for systematics in the data are producing biased results or that $\Lambda$CDM is an incorrect/incomplete description of Nature. We conclude that only future independent high-precision CMB temperature and polarization measurements could provide a definitive answer.

We use a semianalytic model of galaxy formation to compare the predictions of two quenching scenarios: halo quenching and black-hole (BH) quenching. After calibrating both models so that they fit the mass function of galaxies, BH quenching is in better agreement with the fraction of passive galaxies as a function of stellar mass $M_*$ and with the galaxy morphological distribution on a star-formation-rate vs. $M_*$ diagram. Besides this main finding, there are two other results from this research. First, a successful BH-quenching model requires that minor mergers contribute to the growth of supermassive BHs. If galaxies that reach high $M_*$ through repeated minor mergers are not quenched, there are too many blue galaxies at high masses. Second, the growth of BHs in mergers must become less efficient at low masses in order to reproduce the $M_{\rm BH}$--$M_*$ relation and the passive fraction as a function of $M_*$, in agreement with the idea that supernovae prevent efficient BH growth in systems with low escape speeds. Our findings are consistent with a quasar-feedback scenario in which BHs grow until they are massive enough to blow away the cold gas in their host galaxies and to heat the hot circumgalactic medium to such high entropy that its cooling time becomes long. They also support the notion that quenching and maintenance correspond to different feedback regimes.

We study a renormalizable model of Dirac fermion dark matter (DM) that communicates with the Standard Model (SM) through a pair of mediators -- one scalar, one fermion -- in the representation $(\boldsymbol{6},\boldsymbol{1}, \tfrac{4}{3})$ of the SM gauge group $\text{SU}(3)_{\text{c}} \times \text{SU}(2)_{\text{L}} \times \text{U}(1)_Y$. While such assignments preclude direct coupling of the dark matter to the Standard Model at tree level, we examine the many effective operators generated at one-loop order when the mediators are heavy, and find that they are often phenomenologically relevant. We reinterpret dijet and pair-produced resonance and $\text{jets} + E_{\text{T}}^{\text{miss}}$ searches at the Large Hadron Collider (LHC) in order to constrain the mediator sector, and we examine an array of DM constraints ranging from the observed relic density $\Omega_{\chi} h^2_{\text{Planck}}$ to indirect and direct searches for dark matter. Tree-level annihilation, available for DM masses starting at the TeV scale, is required in order to produce $\Omega_{\chi} h^2_{\text{Planck}}$ through freeze-out, but loops -- led by the dimension-five DM magnetic dipole moment -- are nonetheless able to produce signals large enough to be constrained, particularly by the XENON1T experiment. In some benchmarks, we find a fair amount of parameter space left open by experiment and compatible with freeze-out. In other scenarios, however, the open space is quite small, suggesting a need for further model-building and/or non-standard cosmologies.

Majoron-like bosons would emerge from a supernova (SN) core by neutrino coalescence of the form $\nu\nu\to\phi$ and $\bar\nu\bar\nu\to\phi$ with 100 MeV-range energies. Subsequent decays to (anti)neutrinos of all flavors provide a flux component with energies much larger than the usual flux from the "neutrino sphere." The absence of 100 MeV-range events in the Kamiokande II and IMB signal of SN 1987A implies that $\lesssim0.03$ of the total energy was thus emitted and provides the strongest constraint on the majoron-neutrino coupling of $g\lesssim 10^{-9}\,{\rm MeV}/m_\phi$ for $100~{\rm eV}\lesssim m_\phi\lesssim100~{\rm MeV}$. It is straightforward to extend our new argument to other hypothetical feebly interacting particles.

We investigate the 5.49 MeV solar axions flux produced in the $p(d,\, ^{3}{\rm He})a$ reaction and analyze the potential to detect it with the forthcoming large underground neutrino oscillation experiment Jiangmen Underground Neutrino Observatory (JUNO). The JUNO detector could reveal axions through various processes such as Compton and inverse Primakoff conversion, as well as through their decay into two photons or electron-positron pairs inside the detector. We perform a detailed numerical analysis in order to forecast the sensitivity on different combinations of the axion-electron ($ g_{ae} $), axion-photon ($g_{a\gamma}$), and isovector axion-nucleon ($ g_{3aN} $) couplings, using the expected JUNO data for different benchmark values of axion mass in a model-independent way. We find that JUNO would improve by approximately one order of magnitude current bounds by Borexino and it has the best sensitivity among neutrino experiments.

The improved sensitivity of third generation gravitational wave detectors opens the possibility of detecting the primordial cosmological stochastic gravitational wave background (SGWB). Detection of the cosmological SGWB is facing a novel challenge: it will likely be masked by the foreground generated by a large number of coalescences of compact binary systems consisting of black holes and/or neutron stars. In this paper, we investigate the possibility of reducing this foreground by removing (notching) the individually resolved compact binary signals in time-frequency space. We establish that such an approach could be used to reach the SGWB sensitivity floor defined by the unresolved part of the compact binaries foreground, which we find to be between $\Omega_{\rm GW} \sim (9.1 \times10^{-12} - 8.6\times10^{-11})$ for a frequency independent energy density spectrum and depending on the rate of coalescing binary neutron star systems. Since third-generation gravitational wave detectors will not be able to resolve all compact binaries, the unresolvable component of the compact binaries foreground may limit the SGWB searches with these detectors.

R-mode oscillations of rotating neutron stars are promising candidates for continuous gravitational wave (GW) observations. The r-mode frequencies for slowly rotating Newtonian stars are well-known and independent of the equation of state (EOS) but for neutron stars, several mechanisms can alter the r-mode frequency of which the relativistic correction is dominant and relevant for most of the neutron stars. The most sensitive searches for continuous GWs are those for known pulsars for which GW frequencies are in targeted narrow frequency bands of few Hz. In this study, we investigate the effect of several state-of-the-art multi-messenger constraints on the r-mode frequency for relativistic, slowly rotating, barotropic stars. Imposing these recent constraints on the EOS, we find that the r-mode frequency range is slightly higher from the previous study and the narrow band frequency range can increase upto 8-25% for the most promising candidate PSR J0537-6910 depending on the range of compactness. We also derive universal relations between r-mode frequency and dimensionless tidal deformability which can be used to estimate the dynamical tide of the r-mode resonant excitation during the inspiral signal. These results can be used to construct the parameter space for r-mode searches in gravitational wave data and also constrain the nuclear equation of state following a successful r-mode detection.

Magnetic reconnection in laser-produced magnetized plasma is investigated by using optical diagnostics. The magnetic field is generated via Biermann battery effect, and the inversely directed magnetic field lines interact with each other. It is shown by self-emission measurement that two colliding plasmas stagnate on a mid-plane forming two planar dense regions, and that they interact later in time. Laser Thomson scattering spectra are distorted in the direction of the self-generated magnetic field, indicating asymmetric ion velocity distribution and plasma acceleration. In addition, the spectra perpendicular to the magnetic field show different peak intensity, suggesting an electron current formation. These results are interpreted as magnetic field dissipation, reconnection, and outflow acceleration. Two-directional laser Thomson scattering is, as discussed here, a powerful tool for the investigation of microphysics in the reconnection region.

The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Most concepts foresee moderate magnetic fields in rather small volumes, similar to those which are currently employed for axion-like particle searches. We propose to use the magnet system of the Compact Muon Solenoid (CMS) experiment after the high luminosity phase of the LHC as a key component for a future detector for gravitational waves in the MHz frequency range. In this paper we briefly discuss a possible cavity concept which can be integrated into CMS and additionally provide a first estimation of its possible sensitivity.

We show that quasinormal spectrum of gravitational perturbations of Schwarzschild - de Sitter black holes contains a new branch of purely imaginary modes. These modes are not algebraically special and we showed that the sum of them form the well-known in the literature exponential asymptotic tail. When the ratio of the event horizon radius to the cosmological horizon vanishes, these quasinormal modes approach modes of empty de Sitter spacetime. Thus, the spectrum consists of the two branches: Schwarzschild branch deformed by the cosmological constant and de Sitter branch deformed by the black hole mass. While the de Sitter branch contains purely imaginary modes only, the oscillatory modes (with nonzero real part) of the Schwarzschild branch can also become purely imaginary for some values of the cosmological constant, for which they approach the algebraically special mode.

One of the simplest ways to account for the observed W-boson mass shift is to introduce the $SU(2)_L$ triplet Higgs boson with zero hypercharge, whose vacuum expectation value is about 3 GeV. If the triplet is heavy enough at $\mathcal{O}(1)$ TeV, it essentially contributes only to $T$ parameter without any conflict to the observation. The presence of a complex triplet Higgs boson raises the $SU(2)_L$ gauge coupling constant to $\alpha_2(M_{\rm PL} )\simeq 1/44$ at the Planck scale. Thanks to this larger gauge coupling constant, we show that the electroweak axion vacuum energy explains the observed cosmological constant provided that the axion field is located near the hill top of the potential at present.

We revisit the possibility that neutrinos undergo non-radiative decay. We investigate the potential to extract information on the neutrino lifetime-to-mass ratio from the diffuse supernova neutrino background. To this aim we explicitly consider the current uncertainties on the core-collapse supernova rate and on the fraction of failed supernovae. We present predictions for the Super-Kamiokande+Gd, the JUNO, the Hyper-Kamiokande and the DUNE experiments that should observe the diffuse supernova neutrino background in the near future. We show the importance of identifying the neutrino mass ordering to break possible degeneracies between DSNB predictions in presence of decay and standard physics.

The Disturbance storm time (Dst) index has been widely used as a proxy for the ring current intensity, and therefore as a measure of geomagnetic activity. It is derived by measurements from four ground magnetometers in the geomagnetic equatorial regions. We present a new model for predicting $Dst$ with a lead time between 1 and 6 hours. The model is first developed using a Gated Recurrent Unit (GRU) network that is trained using solar wind parameters. The uncertainty of the $Dst$ model is then estimated by using the ACCRUE method [Camporeale et al. 2021]. Finally, a multi-fidelity boosting method is developed in order to enhance the accuracy of the model and reduce its associated uncertainty. It is shown that the developed model can predict $Dst$ 6 hours ahead with a root-mean-square-error (RMSE) of 13.54 $\mathrm{nT}$. This is significantly better than the persistence model and a simple GRU model.

Previous studies have claimed that there exist correlations among certain nuclear saturation parameters and neutron star observables, such as the slope of the symmetry energy and the radius of a $1.4M_{\odot}$ neutron star. However, it is not clear whether such correlations are physical or spurious, as they are not observed universally for all equation of state models. In this work, we probe the role of vector self-interaction within the framework of the Relativistic Mean Field model and its role in governing the observable stellar properties and their correlations with nuclear parameters. We confirm that the effect of this term is not only to control the high density properties of the equation of state but also in governing such correlations. We also impose a limit on the maximum strength of the vector self-interaction using recent astrophysical data.

We study the GENERIC hydrodynamic theory for relativistic liquids formulated by \"{O}ttinger and collaborators. We use the maximum entropy principle to derive its conditions for linear stability (in an arbitrary reference frame) and for relativistic causality. In addition, we show that, in the linear regime, its field equations can be recast into a symmetric-hyperbolic form. Once rewritten in this way, the linearised field equations turn out to be a particular realization of the Israel-Stewart theory, where some of the Israel-Stewart free parameters are constrained. This also allows us to reinterpret the GENERIC framework in view of the principles of Extended Irreversible Thermodynamics (EIT).