Papers for Tuesday, Oct 10 2023

We present results on numerical calculations of the sensitivity coefficients, Qmu, of microwave molecular transitions in (13C)H3OH and CH3(18O)H to the hypothetical variation in the fundamental physical constant mu - the electron-to-proton mass ratio. The invariability of mu in time and space is one of the basic assumptions of the Standard Model of particle physics which can be tested at cosmological scales by means of astronomical observations in the Galaxy and external galaxies. Our calculations show that these two methanol isotopologues can be utilized for such tests since their microwave transitions from the frequency interval 1-100 GHz exhibit a large spread in Qmu values which span a range of -109 < Qmu < 78. We show that the thermal emission lines of (13C)H3OH observed in the star-forming region NGC6334I constrain the variability of mu at a level of 3x10^-8 (1{\sigma}), which is in line with the most stringent upper limits obtained previously from observations of methanol (CH3OH) and other molecules in the Galaxy.

This is the second paper in a series, which studies the likelihood that some globular clusters (GCs) of the Milky Way (MW) could have originated from a dwarf satellite galaxy (DSG). Using a large suite of three-body simulations we determine the present-day orbital properties of 154 GCs that could have escaped from 41 MW DSGs over the past $8\,\mathrm{Gyrs}$. For the MW we considered two sets of static and dynamic models which account for the sustained growth of the MW since its birth. We focus on the Magellanic Clouds and Sagittarius. We compare the apogalactic distance, eccentricity, and orbital inclination of the MW GCs with those of runaway GCs from DSGs, to constrain their possible ex-situ origin. We observe a positive correlation between a DSG mass and the dispersion of its runaway GCs in the orbital parameter space of ($R_\mathrm{ap}$, $e$). We provide tables of the identified MW GCs and their likely associated progenitors. In total, we find 29 (19%) MW GCs which could be kinematically associated with MW DSGs. We report, for the first time, 6 and 10 new associations with the Large Magellanic Cloud and the Sagittarius, respectively. For the Sagittarius we predict a concentration of runaway GCs at large apogalactic distances of $R_\mathrm{ap}\approx275-375\,\mathrm{kpc}$, $e\approx0.8$, and a relative inclination of $\Delta\theta\approx20^{\circ}$. So far, there has not been any observed GCs with such orbital elements. Complemented with photometric and spectroscopic observations, and cosmological simulations, the findings from the present study could conclusively settle the debate over the in-situ vs. ex-situ origin of the MW GCs.

We report the discovery of PSJ2107-1611, a fold-configuration 4.3"-separation quadruply lensed quasar with a bright lensed arc. It was discovered using a convolutional neural network on Pan-STARRS gri images of pre-selected quasar candidates with multiple nearby Pan-STARRS detections. Spectroscopic follow-up with EFOSC2 on the ESO 3.58m New Technology Telescope reveals the source to be a quasar at z = 2.673, with the blended fold image pair showing deformed broad lines relative to the other images. The flux ratios measured from optical to near-infrared imaging in the Canada-France-Hawaii Telescope Legacy Survey, Pan-STARRS, the Legacy Surveys, and the Vista Hemisphere Survey are inconsistent with a smooth mass model as the fold pair images are about 15 times too faint. Variability, time delay effects, and reddening are ruled out through multiple-epoch imaging and color information. The system is marginally resolved in the radio in the Very Large Array Sky Survey S-band, where it has a 10 mJy detection. The radio flux ratios are compatible with the smooth mass macromodel. This system offers a unique tool for future studies of quasar structure with strong and microlensing. A more detailed analysis of follow-up with JWST/MIRI, VLT/MUSE, VLT/ERIS, and data from the European Very Long Baseline Interferometer will be presented in an upcoming paper.

Molecular bands of metal oxides and hydrides dominate the optical and near-infrared spectra of M dwarfs. High-resolution spectra of these bands have immense potential for determining many properties of these stars, such as effective temperature, surface gravity, elemental abundances, radial velocity, or surface magnetic fields. Techniques are being developed to do this but remain limited by the current availability and accuracy of molecular data and spectral line lists. This paper reports metal monohydride line lists selected from near-infrared and visible laboratory data to show that specific bands in several electronic transitions can be used to identify CrH, NiH, and FeH in M stars and to determine radial velocities from Doppler shifts. The possibility of measuring magnetic fields is also investigated for FeH and CrH. We used systematic cross-correlation analysis between unpolarised spectra from a selection of M stars and state-specific laboratory line lists. These lists were generated from a combination of existing data and new laboratory laser-excitation spectra recorded at Doppler-limited resolution, in zero-field conditions or in magnetic fields up to 0.6 tesla. Results. We show that transitions at visible wavelengths in FeH and NiH, usually neglected in the analysis of the spectra of M-type stars, do in fact contribute to the spectra, and we demonstrate the influence of magnetic sensitivity on selected transitions in CrH and FeH. Although the new line lists focus on transitions recorded at temperatures significantly lower than those of stellar objects, they remain pertinent because they cover some band-head regions of high spectral density. FeH bands can provide a useful supplement to atomic lines for the analysis of high-resolution optical and near-infrared spectra of M dwarfs. We demonstrate the influence of a magnetic field on CrH signatures around 862 nm.

We study the ultraviolet (UV) continuum $\beta$ slope of a sample of 166 clumps, individual star-forming regions observed in high redshift galaxies. They are hosted by 67 galaxies with redshift between 2 and 6.2, strongly lensed by the Hubble Frontier Fields cluster of galaxies MACS J0416.1-2403. The $\beta$ slope is sensitive to a variety of physical properties, such as the metallicity, the age of the stellar population, the dust attenuation throughout the galaxy, the stellar initial mass function (IMF), and the star-formation history (SFH). The aim of this study is to compare the $\beta$ values of individual clumps with those measured on the entire galaxy, to investigate possible physical differences between these regions and their hosts. We found a median value of $\beta \sim -2.4$, lower than that of integrated galaxies. This result confirms that clumps are sites of intense star formation, populated by young, massive stars, whose spectrum strongly emits in the UV. This is also consistent with the assumption that the dust extinction at the location of the clumps is lower than the average extinction of the galaxy, or that clumps have a different IMF or SFH. We made use of the correlations, discovered for high-redshift galaxies, of the $\beta$ value with those of redshift and UV magnitude, $M_{UV}$, finding that clumps follow the same relations, extended to much fainter magnitudes ($M_{UV}<-13$). We also find evidence of eight clumps with extremely blue ($\beta \lesssim -2.7$) slopes, which could be the signpost of low-metallicity stars and constrain the emissivity of ionizing photons at high redshift.

Synthesized in the cores of stars and supernovae, most metals disperse over cosmic scales and are ultimately deposited well outside the gravitational potential of their host galaxies. Since their presence is well visible through their X-ray emission lines in the hot gas pervading galaxy clusters, measuring metal abundances in the intracluster medium (ICM) offers us a unique view of chemical enrichment of the Universe as a whole. Despite extraordinary progress in the field thanks to four decades of X-ray spectroscopy using CCD (and gratings) instruments, understanding the precise stellar origins of the bulk of metals, and when the latter were mixed on Mpc scales, requires an X-ray mission capable of spatial, non-dispersive high resolution spectroscopy covering at least the soft X-ray band over a large field of view. In this White Paper, we demonstrate how the Line Emission Mapper (LEM) probe mission concept will revolutionize our current picture of the ICM enrichment. Specifically, we show that LEM will be able to (i) spatially map the distribution of ten key chemical elements out to the virial radius of a nearby relaxed cluster and (ii) measure metal abundances in serendipitously discovered high-redshift protoclusters. Altogether, these key observables will allow us to constrain the chemical history of the largest gravitationally bound structures of the Universe. They will also solve key questions such as the universality of the initial mass function (IMF) and the initial metallicity of the stellar populations producing these metals, as well as the relative contribution of asymptotic giant branch (AGB) stars, core-collapse, and Type Ia supernovae to enrich the cosmic web over Mpc scales. Concrete observing strategies are also briefly discussed.

We present the methodology for deriving accurate and reliable cosmological constraints from non-linear scales (<50Mpc/h) with k-th nearest neighbor (kNN) statistics. We detail our methods for choosing robust minimum scale cuts and validating galaxy-halo connection models. Using cross-validation, we identify the galaxy-halo model that ensures both good fits and unbiased predictions across diverse summary statistics. We demonstrate that we can model kNNs effectively down to transverse scales of rp ~ 3Mpc/h and achieve precise and unbiased constraints on the matter density and clustering amplitude, leading to a 2% constraint on sigma_8. Our simulation-based model pipeline is resilient to varied model systematics, spanning simulation codes, halo finding, and cosmology priors. We demonstrate the effectiveness of this approach through an application to the Beyond-2p mock challenge. We propose further explorations to test more complex galaxy-halo connection models and tackle potential observational systematics.

Radio relics are giant sources of diffuse synchrotron radio emission in the outskirts of galaxy clusters that are associated with shocks in the intracluster medium. Still, the origin of relativistic particles that make up relics is not fully understood. For most relics, diffusive shock acceleration (DSA) of thermal electrons is not efficient enough to explain observed radio fluxes. In this paper, we use a magneto-hydrodynamic simulation of galaxy clusters in combination with Lagrangian tracers to simulate the formation of radio relics. Using a Fokker-Planck solver to compute the energy spectra of relativistic electrons, we determine the synchrotron emission of the relic. We find that re-acceleration of fossil electrons plays a major role in explaining the synchrotron emission of radio relics. Particles that pass through multiple shocks contribute significantly to the overall luminosity of a radio relic and greatly boosts the effective acceleration efficiency. Furthermore, we find that the assumption that the luminosity of a radio relic can be explained with DSA of thermal electrons leads to an overestimate of the acceleration efficiency by a factor of more than $10^3$.

The analysis of the mid-infrared spectra helps understanding the composition of the gas in the inner, dense and warm terrestrial planet forming region of disks around young stars. ALMA has detected hydrocarbons in the outer regions of the planet forming disk and Spitzer detected \ce{C2H2} in the inner regions. JWST- MIRI provides high spectral resolution observations of \ce{C2H2} and a suite of more complex hydrocarbons are now reported. Interpreting the fluxes observed in the spectra is challenging and radiation thermo-chemical codes are needed to properly take into account the disk structure, radiative transfer, chemistry and thermal balance. Various disk physical parameters like the gas-to-dust ratio, dust evolution including radial drift, dust growth and settling can affect the fluxes observed in the mid-IR. Still, thermo-chemical disk models were not always successful in matching all observed molecular emission bands simultaneously. The goal of this project is two-fold. We analyse the warm carbon chemistry in the inner regions of the disk, i.e. within 10 au to find pathways forming \ce{C2H2} potentially missing from the existing chemical networks. Second, we analyse the effect of the new chemistry on the line fluxes of acetylene. We use radiative thermo-chemical disk code {P{\small RO}D{\small I}M{\small O}} to expand the hydrocarbon chemistry that occurs in a typical standard T Tauri disks. We used the UMIST and the KIDA rate databases for collecting reactions for the species. We include a number of three-body and thermal decomposition reactions from STAND2020 network. We included isotopomers for the species that were present in the databases. The chemistry is then analysed in the regions that produce observable features in the mid-infrared spectra. The effect of expanding the hydrocarbon chemistry on the mid-infrared spectra is studied. Acetylene is formed via two ....

A quasi-nonlinear field theory which describes how to take ensemble averages that are unique to the Collisionless Boltzmann Equation is described. The assumption that the ensemble average of the distribution function is equal to the extremum entropy state, $\langle f \rangle = f_0$ is taken apart and shown to be wrong. An application describes the nonlinear saturation of Jeans' instability, and the gravitational amplification of Poisson noise.

G106.3$+$2.7, commonly considered a composite supernova remnant (SNR), is characterized by a boomerang-shaped pulsar wind nebula (PWN) and two distinct ("head" & "tail") regions in the radio band. A discovery of very-high-energy (VHE) gamma-ray emission ($E_\gamma > 100$ GeV) followed by the recent detection of ultra-high-energy (UHE) gamma-ray emission ($E_\gamma > 100$ TeV) from the tail region suggests that G106.3$+$2.7 is a PeVatron candidate. We present a comprehensive multi-wavelength study of the Boomerang PWN (100" around PSR J2229+6114) using archival radio and Chandra data obtained from two decades ago, a new NuSTAR X-ray observation from 2020, and upper limits on gamma-ray fluxes obtained by Fermi and VERITAS observatories. The NuSTAR observation allowed us to detect a 51.67 ms spin period from the pulsar PSR J2229+6114 and the PWN emission characterized by a power-law model with $\Gamma = 1.52\pm0.06$ up to 20 keV. Contrary to the previous radio study by Kothes et al. 2006, we prefer a much lower PWN B-field ($B\sim3$ $\mu$G) and larger distance ($d \sim 8$ kpc) based on (1) the non-varying X-ray flux over the last two decades, (2) the energy-dependent X-ray PWN size resulting from synchrotron burn-off and (3) the multi-wavelength spectral energy distribution (SED) data. Our SED model suggests that the PWN is currently re-expanding after being compressed by the SNR reverse shock $\sim 1000$ years ago. In this case, the head region should be formed by GeV--TeV electrons injected earlier by the pulsar propagating into the low density environment.

The diagram depicting the abundance ratios [Mg/Mn] vs. [Al/Fe] has gained attention in recent literature as a valuable tool for exploring fundamental aspects of the evolution of the Milky Way and the Local Group. In particular, this combination of elements is supposed to be highly sensitive to the star formation history (SFH), unveiled by the imprints left on those abundances. Unfortunately, a complete discussion on the uncertainties associated is still missing, making it difficult to know how reliable the associated results are. In this paper we analyze, by means of detailed chemical evolution models, the nuclear uncertainties of Mg, Al, Mn and Fe to show how different yields can affect the trends in the [Mg/Mn] vs. [Al/Fe] plane. In fact, if different yield assumptions produce conflicting results, then the [Mg/Mn] vs. [Al/Fe] diagram does not represent a strong diagnostic for the SFH of a galaxy. We discuss the results on the [Mg/Mn] vs. [Al/Fe] diagram, as predicted by several Milky Way (MW) and Large Magellanic Cloud (LMC) chemical evolution models adopting different nucleosynthesis prescriptions. The results show that the literature yields require some corrective factors to reproduce the APOGEE DR17 abundances of Mg, Al and Mn in the MW and that the same factors can also improve the results for the LMC. In particular, we show that by modifying the massive stars yields of Mg and Al the behaviour of the [Mg/Mn] vs. [Al/Fe] plot changes substantially. In conclusion, by changing the yields within their error bars, one obtains trends which differ strongly, making it difficult to draw any reliable conclusion on the SFH of galaxies. The proposed diagram is therefore uncertain from a theoretical point of view and it could represent a good diagnostic for SFH if the uncertainties on the nucleosynthesis of these elements (Mg, Mn, Al and Fe) could be reduced by future stellar calculations.

The NIKA2 camera operating at the IRAM 30 m telescope excels in high-angular resolution mapping of the thermal Sunyaev-Zeldovich effect towards galaxy clusters at intermediate and high-redshift. As part of the NIKA2 guaranteed time, the SZ Large Program (LPSZ) aims at tSZ-mapping a representative sample of SZ-selected galaxy clusters in the catalogues of the Planck satellite and of the Atacama Cosmology Telescope, and also observed in X-ray with XMM Newton or Chandra. Having completed observations in January 2023, we present tSZ maps of 38 clusters spanning the targeted mass ($3 < M_{500}/10^{14} M_{\odot} < 10$) and redshift ($0.5 < z < 0.9$) ranges. The first in depth studies of individual clusters highlight the potential of combining tSZ and X-ray observations at similar angular resolution for accurate mass measurements. These were milestones for the development of a standard data analysis pipeline to go from NIKA2 raw data to the thermodynamic properties of galaxy clusters for the upcoming LPSZ data release. Final products will include unprecedented measurements of the mean pressure profile and mass observable scaling relation using a distinctive SZ-selected sample, which will be key for ultimately improving the accuracy of cluster based cosmology.

We present a collection of classified X-ray sources in Globular Clusters (GCs) observed by the Chandra X-ray Observatory (CXO), including active binaries, cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries. We cross-match the most accurate published positions from multiwavelength observations of these sources to the Chandra Source Catalog (CSC) Release 2.1, and the HST UV Globular Cluster Survey (HUGS) to extract their multiwavelength properties. The dataset can be accessed via an interactive website and used as a training dataset for machine-learning classification of unidentified X-ray sources in GCs.

The orbital architectures of short-period exoplanet systems are shaped by tidal dissipation in their host stars. For low-mass M-dwarfs whose dynamical tidal response comprises a dense spectrum of inertial modes at low frequencies, resolving the frequency dependence of tidal dissipation is crucial to capturing the effect of tides on planetary orbits throughout the evolutionary stages of the host star. We use non-perturbative spectral methods to calculate the normal mode oscillations of a fully-convective M-dwarf modeled using realistic stellar profiles from MESA. We compute the dissipative tidal response composed of contributions from each mode as well as non-adiabatic coupling between the modes, which we find to be an essential component of the dissipative calculations. Using our results for dissipation, we then compute of the evolution of circular, coplanar planetary orbits under the influence of tides in the host star. We find that orbital migration driven by resonance locking affects the orbits of Earth-mass planets at orbital periods $P_{\rm orb} \lesssim 1.5$ day and of Jupiter-mass planets at $P_{\rm orb} \lesssim 2.5$ day. Due to resonantly-driven orbital decay and outward migration, we predict a dearth of small planets closer than $P_{\rm orb} \sim 1$ day and similarly sparse numbers of more massive planets out to $P_{\rm orb} \sim 3$ day.

The KAPPA package is designed for calculations of optically thin spectra for the non-Maxwellian \k{appa}-distributions. This paper presents extension of the database to allow calculations of the spectra for extreme values of \k{appa} < 2, which are important for accurate diagnostics of the \k{appa}-distributions in the outer solar atmosphere. In addition, two improvements were made to the ionization equilibrium calculations within the database. First, the ionization equilibrium calculations now include the effect of electron impact multi-ionization (EIMI). Although relatively unimportant for Maxwellian distribution, the EIMI becomes important for some elements such as Fe and low values of \k{appa}, where it modifies the ionization equilibrium significantly. Second, the KAPPA database now includes the suppression of dielectronic recombination at high electron densities, evaluated via the suppression factors. We find that at the same temperature, the suppression of dielectronic recombination is almost independent of \k{appa}. The ionization equilibrium calculations for the \k{appa}-distributions are now provided for a range of electron densities.

We investigate the transition scale to homogeneity, $R_H$, using as cosmic tracer the spectroscopic sample of blue galaxies from the Sloan Digital Sky Survey (SDSS). Considering the spatial distribution of the galaxy sample we compute the two point correlation function $\xi(r)$, the scaled counts in spheres $\mathcal{N}(<r)$, and the fractal dimension $\mathcal{D}_2(r)$ to quantify the homogeneity scale in the Local Universe ($0.04 < z < 0.20$). The sample in analysis is compared with {\it random} and {\it mock} catalogues with the same geometry, and the same number of synthetic cosmic objects as the dataset, to calculate the covariance matrix for the errors determination. The criteria adopted for the transition-to-homogeneity follows the literature, it is attained when $\mathcal{D}_2(r)$ reaches the $1$ per cent level of the limit value $3$ (i.e., where it reaches $2.97$) as the scale increases. We obtain $R_H = 70.33 \pm 10.74$ Mpc$/h$, at the effective redshift $z_{\text{eff}}=0.128$, for a sample containing $150\,302$ SDSS blue galaxies with $0.04 < z < 0.20$. Additionally, we perform robustness tests by analysing the homogeneity scale in sub-volumes of the original one, obtaining coherent results; we also check for a possible artefact in our procedure examining a homogeneous synthetic dataset as a pseudo-data, verifying that such systematic is absent. Because our analyses concentrate in data at low redshifts, $z < 0.20$, we find interesting to use cosmography to calculate the radial comoving distances; therefore in this subject our analyses do not use fiducial cosmological model. For completeness, we evaluate the difference of the comoving distances estimation using cosmography and fiducial cosmology.

Streaming instability is considered to be one of the dominant processes to promote planetesimal formation by gravitational collapse of dust clumps. The development of streaming instability is expected to form dust clumps in which the local dust density is strongly enhanced and even greater than the Roche density. The resulting clumps can collapse to form planetesimals. Recent simulations conducted long-term simulations and showed that such strong clumping occurs in a wider parameter space than previously expected. However, the indicated timescale for strong clumping can be on the order of tens to hundreds Keplerian periods. In this paper, we estimate the growth time of dust grains during the pre-clumping phase. We find that the dust growth considerably proceeds before the strong clumping because even the moderate clumping due to streaming instability increases the local dust-to-gas ratio $\gtrsim10$. Depending on the gas sound speed, the dust collision velocity can be kept below $\sim 1\;\mathrm{m/s}$ once sufficiently strong dust clumping occurs. Thus, even silicate grains might have the potential to grow safely toward the size whose Stokes number is unity during the clumping. Our results demonstrate the importance of local dust coagulation during the dust clumping due to streaming instability.

We present a multiwavelength observation of a cool core that does not appear to be associated with any galaxy, in a nearby cluster, Abell~1142. Its X-ray surface brightness peak of $\lesssim2$ keV is cooler than the ambient intracluster gas of $\gtrsim3$ keV, and is offset from its brightest cluster galaxy (BCG) by 80 kpc in projection, representing the largest known cool core -- BCG separation. This BCG-less cool core allows us to measure the metallicity of a cluster center with a much-reduced contribution from the interstellar medium (ISM) of the BCG. XMM-Newton observation reveals a prominent Fe abundance peak of $1.07^{+0.16}_{-0.15}$ Z$_{\odot}$ and an $\alpha/$Fe abundance ratio close to the solar ratio, fully consistent with those found at the centers of typical cool core clusters. This finding hints that BCGs play a limited role in enriching the cluster centers. However, the discussion remains open, given that the $\alpha/$Fe abundance ratios of the orphan cool core and the BCG ISM are not significantly different. Abell~1142 may have experienced a major merger more than 100 Myr ago, which has dissociated its cool core from the BCG. This implies that the Fe abundance peak in cool core clusters can be resilient to cluster mergers. Our recent IRAM 30-m observation did not detect any CO emission at its X-ray peak and we find no evidence for massive runaway cooling in the absence of recent AGN feedback. The lack of a galaxy may contribute to an inefficient conversion of the ionized warm gas to the cold molecular gas.

In order to operationalize the Australia Telescope Compact Array (ATCA) for space situational awareness (SSA) applications, we develop a system model for range and direction of arrival (DOA) estimation based on the interferometric data. We employ the observational data collected from global positioning system (GPS) satellites to evaluate the developed model and demonstrate that, compared to a priori location propagated from the most recent two-line element (TLE), both range and direction information are improved significantly.

Gas flows in the presence of two independently-rotating nested bars remain not fully understood, which is likely to play an important role in fueling the central black hole. We use high-resolution hydrodynamical simulations with detailed models of subgrid physics to study this problem. Our results show that the inner bar in double-barred galaxies can help drive gas flow from the nuclear ring to the center. In contrast, gas inflow usually stalls at the nuclear ring in single-barred galaxies. The inner bar causes a quasi-periodic inflow with a frequency determined by the difference between the two bar pattern speeds. We find that the star formation rate is higher in the model with two bars than in that with one bar. The inner bar in our model gradually weakens and dissolves due to gas inflow over a few billion years. Star formation produces metal-rich/$\alpha$-poor stars which slows the weakening of the inner bar, but does not halt its eventual decay. We also present a qualitative comparison of the gas morphology and kinematics in our simulations with those of observed double-barred galaxies.

This work is researched and designed for China and the Mauna Kea Spectroscopic Explorer. Given the fund limitation and the simplicity of scaling up, a 12-m telescope is selected as an example, which is a Su-Meinel four-mirror system with two Nasmyth foci. One focus is for spectroscopic survey, wherein a strip lens-prism atmospheric dispersion corrector (S-ADC) is used. The selected parameters are as follows: a field of view (FOV) of 1.5{\deg}, f-ratio of 4, wavelength range of 0.36-1.8 micron, telescope site altitude of 4200 m, and maximum zenith distance of 60{\deg}. The designed image quality is that the maximum diameter of 80% geometrical encircled energy (EE80) equals 0.36 arcsec. Approximately 20000 optical fibers can be accommodated in the focal surface of the telescope. The other Nasmyth focus is a four-mirror all-reflecting system, used for refined and infrared observations. The EE80 equals 0.10 arcsec for an FOV of 1.5{\deg}without considering atmospheric dispersion. A subsequent coud\'e system has been designed. Since the S-ADC overcomes the current optical glass size restriction, this 12-m telescope can be magnified in proportion to a 20-m class telescope with almost the same excellent image quality.

An accurate measurement of magnetic field is very important for understanding the formation and evolution of solar magnetic fields. Currently there are two types of solar magnetic field measurement instruments: the filter-based magnetographs and the Stokes polarimeters. The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields. Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types. Our previous studies have shown that, compared to the magnetograms obtained by the Spectro-Polarimeter (SP) on board Hinode, those magnetograms obtained by both the filter-based Solar Magnetic Field Telescope (SMFT) of the Huairou Solar Observing Station (HSOS) and by the filter-based Michelson Doppler Imager (MDI) aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments. Here, using a sample of 75 vector magnetograms of stable alpha sunspots, we compare the vector magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) aboard SDO with co-temporal vector magnetograms obtained by SP/Hinode. Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor. Our study suggests that using the filter-based magnetograph to construct a low spectral resolution Stokes profile, as done by HMI/SDO, can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.

A multi-parameter analysis was conducted to evaluate the impact of meteorological parameters, night sky brightness and seismic hazard on proposed sites for the new optical/infrared Egyptian astronomical telescope. The ERA5 reanalysis data set is used to get the following meteorological parameters: Total cloud coverage fraction, precipitable water vapor, relative humidity, wind speed & direction and Air temperature. To estimate the aerosol optical depth we used the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). Light pollution over the candidate sites was measured from Visible Infrared Imaging Radiometer Suite (VIIRS) Day Night Band (DNB). The seismic input in terms of maximum acceleration and response spectra were computed using a physics-based ground motion approach to assess the seismic hazards and consequently the designation of seismic resistant structure for the proposed sites to be able to assess the seismic hazards for the candidate sites. Of the seven nominated sites, two sites are found to have the best measurements and might be considered future sites for the new Egyptian Astronomical telescope. The first site is located in the south of the Sinai peninsula, while the second one is located in the Red Sea mountains region.

On 8 November 2013 a halo-type coronal mass ejection (CME) was observed, together with flares and type II radio bursts, but the association between the flares, radio bursts, and the CME was not clear. Our aim is to identify the origin of the CME and its direction of propagation, and to exclude features that were not connected to it. On the Earth-facing side, a GOES C5.7 class flare occurred close to the estimated CME launch time, followed by an X1.1 class flare. The latter flare was associated with an EUV wave and metric type II bursts. On the far side of the Sun, a filament eruption, EUV dimmings, and ejected CME loops were observed by imaging instruments onboard the Solar TErrestrial RElations Observatory (STEREO) spacecraft that were viewing the backside of the Sun. The STEREO radio instruments observed an interplanetary (IP) type II radio burst at decameter-hectometric wavelengths, which was not observed by the radio instrument onboard the Wind spacecraft located at L1 near Earth. We show that the halo CME originated from the eruption on the far side of the Sun, and that the IP type II burst was created by a shock wave ahead of the halo CME. The radio burst remained unobserved from the earthside, even at heliocentric source heights larger than 9 solar radii. During the CME propagation, the X-class flare eruption caused a small plasmoid ejection earthward, the material of which was superposed on the earlier CME structures observed in projection. The estimated heights of the metric type II burst match well with the EUV wave launched by the X-class flare. As this radio emission did not continue to lower frequencies, we conclude that the shock wave did not propagate any further. Either the shock driver died out, as a blast wave, or the driver speed no longer exceeded the local Alfven speed.

We present the discovery and studies of the helium-rich, fast-evolving supernova (SN) 2021agco at a distance of $\sim$ 40 Mpc. Its early-time flux is found to rise from half peak to the peak of $-16.06\pm0.42$ mag in the $r$ band within $2.4^{+1.5}_{-1.0}$ days, and the post-peak light curves also decline at a much faster pace relative to normal stripped-envelope SNe of Type Ib/Ic. The early-time spectrum of SN~2021agco ($t \approx 1.0$ days after the peak) is characterized by a featureless blue continuum superimposed with a weak emission line of ionized C III, and the subsequent spectra show prominent He I lines. Both the photometric and spectroscopic evolution shows close resemblances to SN 2019dge, which is believed to have an extremely stripped progenitor. We reproduce the multicolor light curves of SN 2021agco with a model combining shock-cooling emission with \Ni decay. The best-fit results give an ejecta mass of $\approx 0.3$~M$_\odot$ and a synthesized nickel mass of $\approx 2.2\times10^{-2}$~M$_\odot$. The progenitor is estimated to have an envelope radius $R_{\rm env} \approx 80$~R$_\odot$ and a mass $M_{\rm env} \approx 0.10$~M$_\odot$. All these suggest that SN~2021agco can be categorized as an ultrastripped SN~Ib, representing the closest object of this rare subtype. This SN is found to explode in the disk of an Sab-type galaxy with an age of $\sim 10.0$~Gyr and low star-forming activity. Compared to normal SNe Ib/c, the host galaxies of SN 2021agco and other ultrastripped SNe tend to have relatively lower metallicity, which complicates the properties of their progenitor populations.

We performed a HST/WFC3-IR imaging survey of the young stellar cluster NGC 2024 in three filters probing the 1.4~$\mu$m H$_2$O absorption feature, characteristic of the population of low mass and sub-stellar mass objects down to a few Jupyter masses. We detect 812 point sources, 550 of them in all 3 filters with signal to noise greater than 5. Using a distance-independent two-color diagram we determine extinction values as high as $A_V\simeq 40$. We also find that the change of effective wavelengths in our filters results in higher $A_V$ values as the reddening increases. Reconstructing a dereddened color-magnitude diagram we derive a luminosity histogram for both the full sample of candidate cluster members and for an extinction-limited sub-sample containing the 50% of sources with $A_V\lesssim 15$. Assuming a standard extinction law like Cardelli et al. (1989) with a nominal $R_V$=3.1 we produce a luminosity function in good agreement with the one resulting from a Salpeter-like Initial Mass Function for a 1~Myr isochrone. There is some evidence of an excess of luminous stars in the most embedded region. We posit that the correlation may be due to those sources being younger, and therefore overluminous than the more evolved and less extinct cluster's stars. We compare our classification scheme based on the depth of the 1.4$\mu$m photometric feature with the results from the spectroscopic survey of Levine et al. (2006), and we report a few peculiar sources and morphological features typical of the rich phenomenology commonly encountered in young star-forming regions.

We present results from the first dedicated study in the time domain of the hard X-ray variability behavior of blazars on long timescales based on $\sim$13 years of continuous hard X-ray data in the 14-195 keV band. We use monthly-binned data from the recent 157-month Swift-BAT catalog to characterize the hard X-ray variability of 127 blazars and search for potential differences between the variability of BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs). A significant portion of the blazars in the sample ($\sim$37%) do not show statistically significant hard X-ray variability on monthly timescales, which is deeply at odds with previous studies that show that blazars are highly variable in the X-rays and other energy bands on a wide range of timescales. We also find that, on average, the FSRQs and BL Lacs for which we do detect variability exhibit similar flux variability; this suggests that the variability in these FSRQs is not necessarily driven by variations in the source function of scattered external radiation arriving from extended regions, and that it is instead possibly driven by processes that lead to variations in particle injection. In addition, only five blazars in our sample show significant spectral variability in the long-term light curves. For 3 blazars, we find that a power law that changes slope on monthly timescales is sufficient to characterize the variable hard X-ray spectrum, suggesting that, at least for some bright blazars, the long-term spectra in the hard X-rays may be described in a relatively simple fashion.

Neutrinos are known to undergo flavor conversion processes among the three flavors. The fast flavor conversion (FFC) has been the central piece of flavor conversions taking place in core-collapse supernovae (CCSNe) due to its shorter timescale to the completion of flavor conversion compared to other types of flavor conversion. Although the ordinary collisions between neutrinos and matter were once thought to decohere neutrinos and thus damp flavor conversions, it was recently realized that they can also induce the flavor conversion. The linear analysis showed that the so-called collisional flavor instability or CFI occurs in the absence of FFC. In this paper, we investigate if CFI takes place in of the post-bounce core of CCSNe, using the results of spherically symmetric Boltzmann simulations of CCSNe for four progenitor models with different masses. We also provide a necessary (but not sufficient) condition of matter properties for the occurrence of CFI in optically thick and semi-transparent regions; baryon mass density ($\rho$), electron fraction ($Y_e$), and the degeneracy of electron-type neutrinos ($\eta_{\nu_e}$) need to be $10^{10} {\rm g/cm^3} \lesssim \rho \lesssim 10^{12} {\rm g/cm^3}$, $Y_e\lesssim 0.4$, and $\eta_{\nu_e} \lesssim 0.5$, respectively. This condition allows us to easily locate the place of possible CFI occurence without detailed stability analyses, which is useful for analyzing CFI in CCSN models phenomenologically

Water fountains (WFs) are thought to be objects in the morphological evolution of the circumstellar envelopes of low- and intermediate-mass evolved stars, transitioning from spherically symmetric to asymmetric shapes. We used databases of circumstellar 1612 MHz OH and 22.235 GHz H$_2$O maser sources to search for new WF candidates using the criterion of a larger velocity range of the H$_2$O maser emission compared to that of the OH maser emission. Thus, it is in principle possible to identify WFs with an H$_2$O velocity ranges smaller than those for the previously known WFs. For the OH maser line, we analyzed database entries of 8,474 observations from 2,195 sources, and 6,085 observations from 3,642 sources for H$_2$O maser line. After a close examination of the velocity ranges and line profiles, we identified 11 sources that meet the criterion mentioned above. We examined the IRAS colors of the selected sources and found that two of them (IRAS 19069+0916 and IRAS 19319+2214) are in the color region for post-AGB stars. We find that the maser velocity criterion can discover other astrophysically interesting objects than just WFs. Such objects may include peculiar planetary nebulae with maser emissions and stellar merger remnants.

Context. The dust in the active galactic nuclei is clearly present right outside the broad-line region (BLR), in the form of a dusty molecular torus. However, some models of the BLR predict that dust may also exist within the BLR. Aims. We study the reprocessing of the radiation by the BLR with the aim to see how the presence of the dust affects the reprocessed continuum and the line properties. Methods. We calculate a range of models with the use of CLOUDY photoionization code for dusty and dustless plasma. We pay particular attention to the well-studied object NGC 5548, and we compare the line equivalent width predictions with the observed data for this object. Results. We obtain a rough agreement between the expected equivalent widths of the H\b{eta} and Mg II lines with observed values for NGC 5548 for the line distances implied by the time-delay measurement (for H\b{eta}) and by the radius-luminosity relation (for Mg II) when the medium is dusty. The incident radiation is then consistent with the radiation seen by the observer, no shielding between the inner disk and the BLR is required. High ionization lines like He II, however, form clearly in the inner dustless region. When the additional absorber is present, the H\b{eta} emitting region moves closer, to the dustless part of the accretion disk surface.

Context. Transition blazars exhibit a shift from one subclass to another during different flux states, making their study crucial to understand the underlying physics of blazars. Aims. To probe the origin of multi-wavelength emission from the transition blazar B2 1308+326 using 14-year long gamma-ray light curve from Fermi and the quasi-simultaneous data from Swift. Methods. We used the Bayesian Block algorithm to identify epochs of flaring and quiescent flux states and modelled the broadband SEDs for those epochs. We employed the one-zone leptonic model in which the synchrotron emission is responsible for the low energy part of the SED and the high energy part is produced by the IC emission of external seed photons. We also investigated its multiband variability properties, gamma-ray flux distribution and the correlation between optical and gamma-ray emissions. Results. We observed a historically bright flare from B2 1308+326 across the optical-to-gamma bands during June-July 2022. The highest daily-averaged gamma-ray flux was (14.24$\pm$2.36) $\times$ 10$^{-7}$ ph cm$^{-2}$ s$^{-1}$ detected on 2022 July 1. The gamma-ray flux distribution was found to be log-normal. The optical and gamma-ray emissions are well correlated with zero time lag. The synchrotron peak frequency changes from 9 $\times$ 10$^{12}$ Hz to 6 $\times$ 10$^{14}$ Hz together with a decrease in the Compton dominance providing a hint of source transition from a LSP to an ISP. The SEDs for those two states are well-fitted by one-zone leptonic models. The parameters in the model fits are essentially consistent between both SEDs, except for the Doppler beaming factor which changes from 13.4 to 27 during the transition. Conclusions. An increase in the Doppler factor could be responsible for both the flare and the transition of B2 1308+326 from LSP to ISP blazar.

Aims. We aim to investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarisation observations carried out between 2017 and 2023 using three ground-based telescopes. Methods. We examined an extensive dataset comprised of 138 intraday (observing duration shorter than a day) light curves (LCs) of S4 0954+65 for flux, spectral, and polarisation variations on diverse timescales. For the variable LCs, we computed the minimum variability timescales. We investigated flux-flux correlations and colour variations to look for spectral variations on long (several weeks to years) timescales. Additionally, we looked for connections between optical R-band flux and polarisation degree. Results. We found significant variations in 59 out of 138 intraday LCs. We detected a maximum change of 0.58$\pm$0.11 in V-band magnitude within $\sim$2.64 h and a corresponding minimum variability timescale of 18.21$\pm$4.87 mins on 2017 March 25. During the course of our observing campaign, the source brightness changed by $\sim$4 magnitudes in V and R bands; however, we did not find any strong spectral variations. The slope of the relative spectral energy distribution was 1.37$\pm$0.04. The degree of polarisation varied from $\sim$ 3% to 39% during our monitoring. We observed a change of $\sim$120 degrees in polarisation angle (PA) within $\sim$3 h on 2022 April 13. No clear correlation was found between optical flux and the degree of polarisation. Conclusions. The results of our optical flux, colour, and polarisation study provide hints that turbulence in the relativistic jet could be responsible for the intraday optical variations in the blazar S4 0954+65. However, the long-term flux variations may be caused by changes in the Doppler factor.

We explore the possibility that high-energy (HE) neutrinos produced at mildly relativistic shocks can be annihilated with low-energy (LE) neutrinos emitted from the accretion disk around a black hole in binary neutron star mergers and rare core-collapse supernovae. For HE neutrinos produced close to the stellar center ($\lesssim 10^{9}-10^{11}$ cm), we find that the emerging all-flavor spectrum for neutrinos of $E\gtrsim 0.1$ PeV could be modified by a factor $E^{-n}$ with $n\approx 0.4-0.5$. Flavor evolution of LE neutrinos does not affect this result but can change the emerging flavor composition of HE neutrinos. As a consequence, the above annihilation effect needs to be considered for HE neutrinos produced at nonrelativistic or mildly relativistic shocks at small radii. In particular, we point out that models of core-collapse supernovae with slow jets and charmed meson decay can better fit the diffuse HE neutrino flux observed by IceCube if annihilation of HE and LE neutrinos is taken into account. Moreover, the relevance of charmed meson and the annihilation effect can be tested by precise measurements of the diffuse neutrino spectrum and flavor composition.

This paper presents the results of 475 hours of interferometric observations with the Australia Telescope Compact Array towards the Spiderweb protocluster at \(z=2.16\). We search for large, extended molecular gas reservoirs among 46 previously detected CO(1-0) emitters, employing a customised method we developed. Based on the CO emission images and position-velocity diagrams, as well as the ranking of sources using a binary weighting of six different criteria, we have identified 14 robust and 7 tentative candidates that exhibit large extended molecular gas reservoirs. These extended reservoirs are defined as having sizes greater than 40 kpc or super-galactic scale. This result suggests a high frequency of extended gas reservoirs, comprising at least \(30 \%\) of our CO-selected sample. An environmental study of the candidates is carried out based on N-th nearest neighbour and we find that the large molecular gas reservoirs tend to exist in denser regions. The spatial distribution of our candidates is mainly centred on the core region of the Spiderweb protocluster. The performance and adaptability of our method are discussed. We found 13 (potentially) extended gas reservoirs located in nine galaxy (proto)clusters from the literature. We noticed that large extended molecular gas reservoirs surrounding (normal) star-forming galaxies in protoclusters are rare. This may be attributable to the lack of observations low-J CO transitions and the lack of quantitative analyses of molecular gas morphologies. The large gas reservoirs in the Spiderweb protocluster are a potential source of the intracluster medium seen in low redshift Virgo- or Coma-like galaxy clusters.

The study of reheating in inflationary models is crucial for understanding the early universe and gaining insights into inflationary dynamics and parameters. The reheating temperature $T_{re}$ and the duration of the reheating phase, quantified by the number of $e$-folds $N_{re}$, have significant implications for particle production, thermalization, and the primordial power spectrum. The duration of reheating affects particle abundance, including dark matter, and shapes the primordial power spectrum and cosmic microwave background anisotropies. By combining cosmological observations and theoretical considerations, we can constrain both $T_{re}$ and $N_{re}$, which in turn constrain the spectral index $n_s$, tensor-to-scalar ratio $r$, and inflation model parameters. Utilizing consistency relations among observables, such as $n_s$ and $r$, provides additional constraints on inflationary models and determines bounds for other observables like the running of the scalar spectral index. These bounds are valuable for assessing the viability of models and can serve to specify priors in Bayesian analyses of specific models. As an example of how to proceed, we study in detail a particular case of a generalized $\alpha$-attractor model that accurately reproduces observed quantities. We present equations for the conditions of instantaneous reheating, establish consistency relations, and explore the generalized $\alpha$-attractor model using cosmological data.

In a gaseous medium, dynamical friction (DF) reaches a maximum when the orbital speed of a (point-like) perturber moving on a circular orbit is close to the sound speed. Therefore, in a quasi-steady state, eccentric orbits of perturbers approaching the sound barrier (from below) should rapidly circularize as they experience the strongest drag at pericenter passage. To investigate this effect, we extend the solution of Desjacques et al. 2022 for circular DF in a uniform gaseous medium to eccentric Keplerian orbits. We derive an approximation to the steady-state DF force, which is valid for eccentricities as high as $e=0.9$ in a limited range of Mach number around the transition to supersonic regime. We validate our analytical result with 3-dimensional simulations of the gas density response. Although gaseous DF generally dissipates orbital energy, we find that it can be directed along the motion of the perturber near pericenter passage when the eccentricity is $e\gtrsim 0.9$. We apply our results to compute the long-time evolution of the orbital parameters. Most trajectories tend to circularize as the perturber moves into the supersonic regime. However, orbits with eccentricities $e\gtrsim 0.8$ below the sound barrier experience a slight increase in eccentricity as they loose orbital energy. Possible extensions to our analytical approach are also discussed.

The Gaia-Sausage-Enceladus~(GSE) stands out as the largest known ancient accretion event in the Milky Way~(MW) history. Despite this significance, the parameters of its progenitor galaxy are still poorly constrained. We identify GSE stars from the APOGEE DR17 using Gaussian mixture models and recover a negative radial metallicity gradient for the GSE debris within the MW stellar halo, with a magnitude of $\approx -0.014^{-0.002}_{-0.022}$ dex/kpc. We argue that this gradient reflects the radial metallicity gradient of the GSE galaxy progenitor before it was disrupted by the MW. By investigating the cosmological HESTIA simulations and $N$-body models of galaxy mergers, we constrain the radial metallicity gradient of the GSE-progenitor to be $\approx -0.1^{-0.06}_{-0.15}$ dex/kpc. We, therefore, propose that a chemical tagging of accreted stars using their integrals of motion, although they are not conserved during mergers, provide essential information about the structure and the past of systems accreted onto the MW.

A vast majority of bright comets between the late 2nd century and the early 18th century, moving in potentially Kreutz orbits according to Hasegawa & Nakano (2001), was first sighted between 2 and 16 days after perihelion, thanks to the spectacular tails that they were then displaying. In this paper I examine the basic properties of the post-perihelion tails of the three brightest Kreutz sungrazers of the 19th and 20th centuries -- the Great March Comet of 1843 (C/1843 D1), the Great September Comet of 1882 (C/1882 R1), and Ikeya-Seki (C/1965 S1). As the pre-perihelion tail of a sungrazer sublimates completely at perihelion, the development of its post-perihelion tail starts from scratch. In the early days after perihelion, the tail length grows rapidly on account of the plasma component. At some point the dust takes over, reaching a peak length weeks later. As the geocentric distance continues to increase and the surface brightness to decline, the tail's shortening sets in. The dust tails of Ikeya-Seki and the 1843 sungrazer contained grains subjected to solar radiation pressure accelerations not exceeding 0.6-0.7 the solar gravitational acceleration, the dust tail of the 1882 sungrazer was more complex. For weeks this comet appeared like a comet in a comet, a result of disintegration of a distant companion near perihelion. Evening Kreutz sungrazers are found to have longer tails than morning ones because of geometry. Other issues are discussed and extensive sets of tail data are provided.

The near-term capability to characterize terrestrial exoplanet atmospheres may bring us closer to discovering alien life through atmospheric data. However, remotely detectable candidate biosignature gases are subject to possible false positive signals as they can also be produced abiotically. To distinguish biological, abiotic and anomalous sources of these atmospheric gases, we take a complex systems approach using chemical reaction network analysis of planetary atmospheres. We simulated 30,000 terrestrial atmospheres, organized in two datasets: Archean Earth-like worlds and modern Earth-like worlds. For Archean Earth-like worlds we study cases where CH4 is produced abiotically via serpentinization, biologically via methanogenesis, or from anomalous sources. We also simulate modern Earth-like atmospheres with and without industrial CFC-12. Network properties like mean degree and average shortest path length effectively distinguish scenarios where CH4 is produced from methanogenesis and serpentinization, with biologically driven networks exhibiting higher connectivity and efficiency. Network analysis also distinguishes modern Earth atmospheres with CFC-12 from those without, with industrially polluted networks showing increased mean degree. Using Bayesian analysis, we demonstrate how atmospheric network property statistics can provide stronger confidence for ruling out biological explanations compared to gas abundance statistics alone. Our results confirm how a network theoretic approach allows distinguishing biological, abiotic and anomalous atmospheric drivers, including ruling out life-as-we-know-it as a possible explanation. Developing statistical inference methods for spectral data that incorporate network properties could significantly strengthen future biosignature detection efforts.

Studying the magnetic fields of exoplanets will provide valuable information about their interior structures, atmospheric properties (escape and dynamics), and potential habitability. One of the most promising methods to detect exoplanetary magnetic fields is to study their auroral radio emission. However, there are no confirmed detections of an exoplanet in the radio despite decades of searching. Recently, Turner et al. 2021 reported a tentative detection of circularly polarized bursty emission from the $\tau$ Boo exoplanetary system using LOFAR low-frequency beamformed observations. The likely source of this emission was presumed to be from the $\tau$ Boo planetary system and a possible explanation is radio emission from the exoplanet $\tau$ Boo b, produced via the cyclotron maser mechanism. Assuming the emission is from the planet, Turner et al. 2021 found that the derived planetary magnetic field is compatible with theoretical predictions. The need to confirm this tentative detection is critical as a conclusive detection would have broad implications for exoplanetary science. In this study, we performed a follow-up campaign on the $\tau$ Boo system using the newly commissioned NenuFAR telescope in 2020. We do not detect any bursty emission in the NenuFAR observations. There are many different degenerate explanations for our non-detection. For example, the original bursty signal may have been caused by an unknown instrumental systematic. Alternatively, the planetary emission from $\tau$ Boo b is variable. As planetary radio emission is triggered by the interaction of the planetary magnetosphere with the magnetized stellar wind, the expected intensity of the planetary radio emission varies greatly with stellar rotation and along the stellar magnetic cycle. More observations are needed to fully understand the mystery of the possible variability of the $\tau$ Boo b radio emission.

Using the multi-epoch mid-infrared (MIR) photometry from the Wide-field Infrared Survey Explorer spanning a baseline of $\sim10$ yr, we extensively investigate the MIR variability of nearby active galactic nuclei (AGNs) at $0.15 < z < 0.4$. We find that the ensemble structure function in the W1 band ($3.4\ \mu$m) can be modeled with a broken power law. Type 1 AGNs tend to exhibit larger variability amplitudes than type 2 AGNs, possibly due to the extinction by the torus. The variability amplitude is inversely correlated with the AGN luminosity, consistent with a similar relation known in the optical. Meanwhile, the slope of the power law increases with AGN luminosity. This trend can be attributed to the fact that the inner radius of the torus is proportional to the AGN luminosity, as expected from the size$-$luminosity relation of the torus. Interestingly, low-luminosity type 2 AGNs, unlike low-luminosity type 1 AGNs, tend to exhibit smaller variability amplitude than do high-luminosity AGNs. We argue that either low-luminosity type 2 AGNs have distinctive central structures due to their low luminosity or their MIR brightness is contaminated by emission from the cold dust in the host galaxy. Our findings suggest that the AGN unification scheme may need to be revised. We find that the variability amplitude of dust-deficient AGNs is systematically larger than that of normal AGNs, supporting the notion that the hot and warm dust in dust-deficient AGNs may be destroyed and reformed according to the strength of the ultraviolet radiation from the accretion disk.

Photoelectric observations of night sky brightness (NSB) at different zenith distances and azimuths, covering all the sky, at the Egyptian Kottamia Astronomical observatory (KAO) site of coordinates {\phi} = 29{\deg}55.9'N and {\lambda} = 31{\deg}49.5' E, were done using a fully automated photoelectric photometer (FAPP). The Bessel wide range system (UBVRI) is used for the first time to observe NSB for three consecutive nights (1 to 3 August, 2022) under good seeing conditions after the moon sets. The deduced results were taken in photons and converted into mag/arcsec2. The average zenith sky brightness for U, B, V, R and I filters are found to be 20.49, 20.38, 19.41, 18.60 and 17.94 mag/arcsec2 respectively. The average color indices (U-B), (B-V), (V-R) and (R-I), at the zenith are detected to be 0.11, 0.98, 0.81 and 0.66, respectively. We plotted the isophotes of the sky brightness at KAO in U, B, V, R and I colors (filters) and determined both the average atmospheric extinction and sky transparency through these UBVRI filters. The atmospheric and other meteorological conditions were taken into our consideration during the observational nights. The results of the current study illustrate the main impact of the new cities built around KAO on the sky glow over it, and which astronomical observations are affected.

We present 36 new mid-eclipse times obtained between 2017 and 2023 using the T100 telescope in Turkey, extending the time span of the $O-C$ diagram to 25 years. Once again, these new observations show significant deviations from previous published models that were able to explain the observed variations of the binary period. We investigate two plausible explanations for this variability: the LTT effect due to the presence of one or two invisible low-mass (planetary) companion(s) in distant circumbinary orbits; other mechanisms, like e.g. the Applegate mechanism, associated with the magnetic cycles of the M-dwarf component of the WD+dM binary. Through MCMC analyzes, we demonstrate that the observed $O-C$ variability can be explained by the presence of a planet with a minimum mass of $\sim9.5 M_J$. This circumbinary planet orbits around the binary system with a period of about 19.5 years, maintaining a stable orbit for a timeline of 10 Myr. By adding a weak LTT signal from a secondary hypothetical planet we achieve statistically better results. However, the orbits of the bodies in a two-planet system remain stable only for a small range of the parameter space. The energy required to power the Applegate and other Applegate-like mechanisms is too high to explain the period variations observed. Thus, on the one hand there is substantial evidence supporting the existence of a planet in the NN Ser system, but on the other hand there are also compelling indications that cast doubt on the existence of a second hypothetical planet.

We have selected galaxies with very high levels of H$\alpha$ emission (EQW(H$\alpha$)$>$700 \AA.) in their central regions from the final data release of the MaNGA survey . Our study focuses on 14 very well-resolved nearby galaxies with stellar masses in the range $9.5 < \log M_*/(M_{\odot}) < 11.5$. We investigate a variety of procedures for selecting galaxy regions that are likely to harbour excess populations of young massive stars, finding that selection in the 2-dimensional space of extinction-corrected H$\alpha$ EQW and [SIII]/[SII] line ratio produces the best results. By comparing stacked spectra covering these regions with stacked spectra covering normal starburst regions with 100\AA$<$EQW(H$\alpha$)$<$200\AA, we obtain the following main results: 1) Clear signatures of excess Wolf Rayet stars are found in half of the H$\alpha$ excess regions, 2) Galaxy regions containing excess Wolf Rayet stars are more often associated with the presence of high-ionization emission lines characteristic of accreting black holes. Excess [NeIII] is detected in 4 out of 8 of the WR regions and there are tentative [FeX] detections in 2 galaxies. 3) Regions of the galaxy with excess Wolf Rayet stars are located where the interstellar medium has larger ionized gas turbulent velocities and higher neutral gas overdensities. We make a first attempt to constrain changes in the high mass end of the stellar initial mass function (IMF) using the HR-pyPopStar evolutionary population synthesis models that include high wavelength-resolution theoretical atmosphere libraries for Wolf Rayet stars.

Imaging spectroscopy is intended to be coupled with adaptive optics (AO) on large telescopes, such as EST, in order to produce high spatial and temporal resolution measurements of velocities and magnetic fields upon a 2D FOV. We propose a Multichannel Subtractive Double Pass (MSDP) incorporated to the EST visible and IR spectrographs, using new generation slicers (56 channels, high spectral resolution) which will benefit of AO and polarimeters. The aim is to produce 56-channel spectra images with the spatial resolution of the AO and reconstitute cubes of instantaneous data (X, Y, lambda) at high cadence, allowing the study of the plasma dynamics and magnetic fields. The MSDP is compatible with most polarimetric methods (we shall discuss only two of them).

Within this proceeding, we introduce the U-Board platform, a versatile platform for signal generation, acquisition and processing, based on a heterogenous processing architecture. Based on this platform we present a readout for Microwave Kinetic Inductance Detectors (MKIDs) for the A-MKID camera for APEX. In addition to the implementation of the readout on this heterogenous architecture, we also present a first comparison of the performance of the readout compared to the currently used readout of the A-MKID camera. Last but not least, we discuss how we plan to miniaturize the current prototype, which is based on commercial off the shelf components.

Recent cosmological observations show a statistically significant tension in the estimated values of the cosmological parameters within the standard $\Lambda$CDM framework. In a recent study, Li and Shafieloo introduced a simple Phenomenological Emergent Dark Energy (PEDE) model, which possesses the same number of parameters as that of the $\Lambda$CDM model. Their research highlighted this model as a viable alternative to $\Lambda$CDM, capable of alleviating the Hubble tension and explaining the late-time cosmic acceleration. Following this, we consider a series of PEDE-type models where a new parameter $b$ is introduced in the dark energy expression that distinguishes one model from the other and is designated as bPEDE models. The PEDE and $\Lambda$CDM models were the special cases of the bPEDE model. In contrast to the PEDE model, the bPEDE model demonstrates the presence of dark energy in the past while indicating its absence in the asymptotic future. Confronting these models with the observational Hubble data (OHD) shows that a series of bPEDE models fit the data better than the PEDE model and the standard $\Lambda$CDM model. Notably, the Hubble constant ($H_0$) value computed using the best-fit bPEDE models closely aligns with the CMBR prediction. It significantly deviates from the local measurement at a significance level of approximately $3.4\sigma$ for the model independent OHD data combination. The outcome suggests reconsidering the systematic uncertainties associated with the local measurement. The best-fit bPEDE models predict the deceleration to acceleration transition at a redshift $z_T \sim 0.78$ which is in close agreement with the $\Lambda$CDM prediction. The age of the universe predicted by the bPEDE model is $\sim 14$ Gyr, slightly higher than the age predicted by the $\Lambda$CDM model. The statefinder trajectory reveals a quintessence nature of dark energy.

We report the discovery of two exoplanets around the M dwarfs GJ 724 and GJ 3988 using the radial velocity (RV) method. We obtained a total of 153 3.5 m Calar Alto/CARMENES spectra for both targets and measured their RVs and activity indicators. We also added archival ESO/HARPS data for GJ 724 and infrared RV measurements from Subaru/IRD for GJ 3988. We searched for periodic and stable signals to subsequently construct Keplerian models, considering different numbers of planets, and we selected the best models based on their Bayesian evidence. Gaussian process (GP) regression was included in some models to account for activity signals. For both systems, the best model corresponds to one single planet. The minimum masses are $10.75^{+0.96}_{-0.87}$ and $3.69^{+0.42}_{-0.41}$ Earth-masses for GJ 724 b and GJ 3988 b, respectively. Both planets have short periods (P < 10 d) and, therefore, they orbit their star closely (a < 0.05 au). GJ 724 b has an eccentric orbit (e = $0.577^{+0.055}_{-0.052}$), whereas the orbit of GJ 3988 b is circular. The high eccentricity of GJ 724 b makes it the most eccentric single exoplanet (to this date) around an M dwarf. Thus, we suggest a further analysis to understand its configuration in the context of planetary formation and architecture. In contrast, GJ 3988 b is an example of a common type of planet around mid-M dwarfs.

The cosmological 21 cm signal is one of the most promising avenues to study the Epoch of Reionization. One class of experiments aiming to detect this signal is global signal experiments measuring the sky-averaged 21 cm brightness temperature as a function of frequency. A crucial step in the interpretation and analysis of such measurements is separating foreground contributions from the remainder of the signal, requiring accurate models for both components. Current models for the signal (non-foreground) component, which may contain cosmological and systematic contributions, are incomplete and unable to capture the full signal. We propose two new methods for extracting this component from the data: Firstly, we employ a foreground-orthogonal Gaussian Process to extract the part of the signal that cannot be explained by the foregrounds. Secondly, we use a FlexKnot parameterization to model the full signal component in a free-form manner, not assuming any particular shape or functional form. This method uses Bayesian model selection to find the simplest signal that can explain the data. We test our methods on both, synthetic data and publicly available EDGES low-band data. We find that the Gaussian Process can clearly capture the foreground-orthogonal signal component of both data sets. The FlexKnot method correctly recovers the full shape of the input signal used in the synthetic data and yields a multi-modal distribution of different signal shapes that can explain the EDGES observations.

The IceCube Neutrino Observatory is a cubic-kilometer Cherenkov detector that is deployed deep in the Antarctic ice at the South Pole. A square kilometer companion surface detector, IceTop, located directly above in the in-ice array, measures cosmic-ray initiated extensive air showers with primary energies between 100 TeV and 1 EeV. By combining the events measured by IceTop and the in-ice detectors of IceCube in coincidence, we can reconstruct the energy spectra for different primary mass groups. Therefore, we provide information about the origin of cosmic rays, in particular, in the transition region from galactic to extra-galactic origin of high-energy cosmic rays. In this contribution we present recent experimental results, as well as prospects by the foreseen enhancement of the surface detectors of IceTop and the future IceCube-Gen2 surface array.

Three-dimensional (3D) radiative magnetohydrodynamics (MHD) simulations are the only way to model stellar atmospheres without any ad hoc parameterisations. Several 3D radiative MHD codes have achieved good quantitative agreement with observables for our Sun. We aim to validate the most up-to-date version of the MURaM code against well established quiet Sun measurements, in particular spatially averaged measurements that are relevant for stellar studies. This validation extends the number of solar observables that MURaM can reproduce with high precision. It is also an essential condition for using MURaM to accurately calculate spectra of other cool stars. We simulate the solar upper convection zone and photosphere harbouring a small-scale-dynamo. Using time series of 3D snapshots we calculate the spectral irradiance, limb darkening and selected spectral lines, which we compare to observations. The computed observables agree well with the observations, in particular the limb darkening of the quiet Sun is reproduced remarkably well.

Be stars make up almost 20% of the B star population, and are rapidly rotating stars surrounded by a disc; however the origin of this rotation remains unclear. Mass transfer within close binaries provides the leading hypothesis, and previous detections of stripped companions to Be stars supporting this. Here, we exploit the exquisite astrometric precision of Gaia to carry out the largest to date comparative study into the binarity of matched samples of nearby B and Be stars from the Bright Star Catalogue. By utilising new ''proper motion anomaly'' values, derived from Gaia DR2 and DR3 astrometric data alongside previous values calculated using Hipparcos and Gaia data, and the Gaia provided RUWE, we demonstrate that we can identify unresolved binaries down to separations of 0.02''. Using these measures, we find that the binary fractions of B and Be stars are similar between 0.04 - 10'', but the Be binary fraction is significantly lower than that of the B stars for separations below 0.04''. As the separation range of these ''missing'' binaries is too large for mass transfer, and stripped companions are not retrieved by these measures, we suggest the companions migrate inwards via binary hardening within a triple system. This confirms statistically for the first time the hypothesis that binary interaction causes the Be phenomenon, with migration causing the dearth of Be binaries between 0.02 - 0.04''. Furthermore, we suggest that triplicity plays a vital role in this migration, and thus in the formation of Be stars as a whole.

Galaxies obey a number of empirical correlations between their radio, {\gamma}-ray, and infrared emission, but the physical origins of these correlations remain uncertain. Here we use the CONGRuENTS model for broadband non-thermal emission from star-forming galaxies, which self-consistently calculates energy-dependent transport and non-thermal emission from cosmic ray hadrons and leptons, to predict radio and {\gamma}-ray emission for a synthetic galaxy population with properties drawn from a large deep-field survey. We show that our synthetic galaxies reproduce observed relations such as the FIR-radio correlation, the FIR-{\gamma} correlation, and the distribution of radio spectral indices, and we use the model to explain the physical origins of these relations. Our results show that the FIR-radio correlation arises because the amount of cosmic ray electron power ultimately radiated as synchrotron emission varies only weakly with galaxy star formation rate as a result of the constraints imposed on gas properties by hydrostatic balance and turbulent dynamo action; the same physics dictates the extent of proton calorimetry in different galaxies, and thus sets the FIR-{\gamma}-ray correlation. We further show that galactic radio spectral indices result primarily from competition between thermal free-free emission and energy-dependent loss of cosmic ray electrons to bremsstrahlung and escape into galactic halos, with shaping of the spectrum by inverse Compton, synchrotron, and ionisation processes typically playing a sub-dominant role. In addition to explaining existing observations, we use our analysis to predict a heretofore unseen correlation between the curvature of galaxies' radio spectra and their pion-driven {\gamma}-ray emission, a prediction that will be testable with upcoming facilities.

Seismic Newtonian noise is predicted to limit the sensitivity of the Einstein Telescope. It can be reduced with coherent noise cancellation techniques using data from seismometers. To achieve the best results, it is important to place the seismic sensors in optimal positions. A preliminary study on this topic was conducted for the Einstein Telescope (ET): it focused on the optimization of the seismic array for the cancellation of Newtonian noise at an isolated test mass. In this paper, we expand the study to include the nested shape of ET, i.e., four test masses of the low-frequency interferometers at each vertex of the detector. Results are investigated in function of the polarization content of the seismic field composed of body waves. The study also examines how performance can be affected by displacing the sensor array from its optimal position or by operating at frequencies other than those used for optimization.

Studying small near-Earth asteroids is important to understand their dynamical histories and origins as well as to mitigate the damage of the asteroid impact to the Earth. We report the results of multicolor photometry of the tiny near-Earth asteroid 2015 RN$_{35}$ using the 3.8 m Seimei telescope in Japan and the TRAPPIST-South telescope in Chile over 17 nights in 2022 December and 2023 January. We observed 2015 RN$_{35}$ across a wide range of phase angles from 2$^{\circ}$ to 30$^{\circ}$ in the $g$, $r$, $i$, and $z$ bands in the Pan-STARRS system. These lightcurves show that 2015 RN$_{35}$ is in a non-principal axis spin state with two characteristic periods of $1149.7\pm0.3$ s and $896.01\pm0.01$ s. We found that a slope of a visible spectrum of 2015 RN$_{35}$ is as red as asteroid (269) Justitia, one of the very red objects in the main belt, which indicates that 2015 RN$_{35}$ can be classified as an A- or Z-type asteroid. In conjunction with the shallow slope of the phase curve, we suppose that 2015 RN$_{35}$ is a high-albedo A-type asteroid. We demonstrated that surface properties of tiny asteroids could be well constrained by intensive observations across a wide range of phase angles. 2015 RN$_{35}$ is a possible mission accessible A-type near-Earth asteroid with a small $\Delta v$ of 11.801 km s$^{-1}$ in the launch window between 2030 and 2035.

We estimate the impact on the stellar evolution of the uncertainties in the $3\alpha$ and the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ reaction rates [...]. We calculated models of low- and intermediate-mass stars for different values of the rates. The $3\alpha$ reaction rate was varied up to $\pm 24\%$, while the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ reaction rate was varied by up to $\pm 35\%$. The models were calculated for two different initial chemical compositions to represent different stellar populations. A $M = 0.67$ $M_{\odot}$ model was chosen as representative of the halo ancient stars, while for disk stars, the $M=1.5$ $M_{\odot}$ and $M=2.5$ $M_{\odot}$ models were considered. The impact of the two reaction rates on the central He-burning lifetime and the asymptotic giant branch (AGB) lifetime, as well as the mass of the C/O core at the central He exhaustion and the internal C and O abundances, was investigated. A variation of the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ reaction rates resulted in marginal differences in the analysed features among the three considered stellar masses, except for the C/O abundances. The central He-burning lifetime changed by less than 4%, while the AGB lifetime was affected only at the 1% level. The internal C and O abundances showed greater variation, with a change of about 15%. The uncertainty in the $3\alpha$ reaction rate mainly influences the C and O central abundances (up to 10%) for all the models considered, and the AGB lifetime for intermediate mass stars (up to 5%). Most of the investigated features were affected by less than 2%. The current uncertainty in the two reaction rates has a negligible effect on the predicted evolutionary time scale with respect to other uncertainty sources. The variability in the chemical profile at the end of the shell He-burning phase is still relevant.

A first look is taken at the NIRSpec 1-5 $\mu$m observations from JWST program 1591 that targets 7 objects along the low-mass stellar life cycle with PAH emission. Spectra extracted from a 1.5$^{\prime\prime}$ radius sized circular aperture are explored, showing a wealth of features, including the 3 $\mu$m PAH complex, the PAH-continuum, and atomic and molecular emission lines from HI, He, H$_{\rm 2}$, and other species. CO$_{\rm 2}$- and H$_{\rm 2}$O-ice absorption and CO emission is also seen. Focusing on the bright-PDR position in M17, the PAH CH stretch falls at 3.29 $\mu$m (FWHM=0.04 $\mu$m). Signs of its 1.68 $\mu$m overtone are confused by line emission in all targets. Multi-component decomposition reveals a possible aliphatic deuterated PAH feature centered at 4.65 $\mu$m (FWHM=0.02 $\mu$m), giving [D/H]$_{\rm alip.}$=31$\pm$12.7%. However, there is little sign of its aromatic counterpart between 4.36-4.43 $\mu$m. There is also little sign of PAH-nitrile emission between 4.34-4.39 $\mu$m. A PAH continuum rises from $\sim$1 to 3.2 $\mu$m, after which it jumps by about a factor of 2.5 at 3.6 $\mu$m, with bumps at 3.8, 4.04, and 4.34 $\mu$m adding structure. The CO$_{\rm 2}$ absorption band in M17 is matched with 10:1 H$_{\rm 2}$O:CO$_{\rm 2}$ ice at 10 K. The $v$=0 pure rotational molecular hydrogen population diagram reveals $>$2200 K UV-pumped gas. The hydrogen Pfund series runs from levels 10 to $>$30. Considering Br$\alpha$/Br$\beta$=0.381$\pm$0.01966 and Case B recombination results in A$_{\rm V}{\simeq}$8. CO emission in IRAS21282+5050 originates from 258 K gas. In-depth spectral-spatial analysis of all features and targets are planned for a series of forthcoming papers.

This work combines spectroscopic and photometric data of the polluted white dwarf WD0141-675 which has a now retracted astrometric super-Jupiter candidate and investigates the most promising ways to confirm Gaia astrometric planetary candidates and obtain follow-up data. Obtaining precise radial velocity measurement for white dwarfs is challenging due to their intrinsic faint magnitudes, lack of spectral absorption lines, and broad spectral features. However, dedicated radial velocity campaigns are capable of confirming close in giant exoplanets (a few M$_{\textrm{Jup}}$) around polluted white dwarfs, where additional metal lines aid radial velocity measurements. Infrared emission from these giant exoplanets is shown to be detectable with JWST MIRI and will provide constraints on the formation of the planet. Using the initial Gaia astrometric solution for WD0141-675 as a case study, if there were a planet with a 33.65 d period or less with a nearly edge on orbit, 1) ground-based radial velocity monitoring limits the mass to $<$ 15.4 M$_{\textrm{Jup}}$, and 2) space-based infrared photometry shows a lack of infrared excess and in a cloud-free planetary cooling scenario, a sub-stellar companion would have to be $<$ 16 M$_{\textrm{Jup}}$ and be older than 3.7 Gyr. These results demonstrate how radial velocities and infrared photometry can probe the mass of the objects producing some of the astrometric signals, and rule out parts of the brown dwarf and planet mass parameter space. Therefore, combining astrometric data with spectroscopic and photometric data is crucial to both confirm, and characterise astrometric planet candidates around white dwarfs.

We test the convergence of fast simulations based on the COmoving Lagrangian Acceleration (COLA) method for predictions of the matter power spectrum, specialising our analysis in the redshift range $1 \le z \le 1.65$, relevant to high-redshift spectroscopic galaxy surveys. We then focus on the enhancement of the matter power spectrum in modified gravity (MG), the boost factor, using the Dvali-Gabadadze-Porrati (DGP) theory as a test case but developing a general approach that can be applied to other MG theories. After identifying the minimal simulation requirements for accurate DGP boost factors, we design and produce a COLA simulation suite that we use to train a neural network emulator for the DGP boost factor. Using MG-AREPO simulations as a reference, we estimate the emulator accuracy to be of $\sim 3\%$ up to $k=5 \, h {\rm Mpc}^{-1}$ at $0 \leq z \leq 2$. We make the emulator publicly available at: https://github.com/BartolomeoF/nDGPemu.

The thermodynamical properties of the intracluster medium (ICM) are driven by scale-free gravitational collapse, but they also reflect the rich astrophysical processes at play in galaxy clusters. At low masses ($\sim 10^{14}$ M$_{\odot}$) and high redshift ($z \gtrsim 1$), these properties remain poorly constrained observationally, due to the difficulty in obtaining resolved and sensitive data. This paper aims at investigating the inner structure of the ICM as seen through the Sunyaev-Zel'dovich (SZ) effect in this regime of mass and redshift. Focus is set on the thermal pressure profile and the scaling relation between SZ flux and mass, namely the $Y_{\rm SZ} - M$ scaling relation. The three galaxy clusters XLSSC~072 ($z=1.002$), XLSSC~100 ($z=0.915$), and XLSSC~102 ($z=0.969$), with $M_{500} \sim 2 \times 10^{14}$ M$_{\odot}$, were selected from the XXL X-ray survey and observed with the NIKA2 millimeter camera to image their SZ signal. XMM-Newton X-ray data were used in complement to the NIKA2 data to derive masses based on the $Y_X - M$ relation and the hydrostatic equilibrium. The SZ images of the three clusters, along with the X-ray and optical data, indicate dynamical activity related to merging events. The pressure profile is consistent with that expected for morphologically disturbed systems, with a relatively flat core and a shallow outer slope. Despite significant disturbances in the ICM, the three high-redshift low-mass clusters follow remarkably well the $Y_{\rm SZ}-M$ relation expected from standard evolution. These results indicate that the dominant physics that drives cluster evolution is already in place by $z \sim 1$, at least for systems with masses above $M_{500} \sim 10^{14}$ M$_{\odot}$.

Based on the recently demonstrated resonant wave-wave process, it is shown that electrons can be accelerated to ultra-relativistic energies in the magnetospheres of radio pulsars. The energization occurs via the resonant interaction of the electron wave (described by a Klein-Gordon (KG) equation) moving in unison with an intense electromagnetic (EM) wave; the KG wave/particle continuously draws energy from EM. In a brief recapitulation of the general theory, the high energy (resonantly enhanced) electron states are investigated by solving the KG equation, minimally coupled to the EM field. The restricted class of solutions, that propagate in phase with EM radiation (functions only of $\zeta=\omega t-kz$), are explored to serve as a possible basis for the proposed electron energization in the radio pulsars. We show that the wave-wave resonant energization mechanism could be operative in a broad class of radio pulsars with periods ranging from milliseconds to the normal values ($\sim 1$ sec); it could drive the magnetospheric electrons to acquire energies from $100$s of TeVs (millisecond pulsars) to $10$ ZeVs (normal pulsars).

People can diagnose the interiors of stars by sensing their pulsations. Pulsation modes, which are determined by the internal state and structure of a star, are typically considered stable over short timescales. These independent pulsation modes have been used in asteroseismology to reconstruct the interior structure of stars. Here, we report the discovery of peculiar pulsation mode interaction details in the high-amplitude $\delta$ Scuti star KIC 6382916 (J19480292+4146558), challenging the reliability of independent pulsation modes as indicators of the star's internal structure. Through analysis of archival data, we found distinct variations in amplitudes and frequencies of three independent pulsation modes and their harmonics/combinations over approximately 20 days. These variations can reach amplitudes of about 140% and frequency variations of about 12%. Correlation analysis of amplitude and frequency variations revealed additional pulsation mode interaction details and patterns. Notably, our findings regarding the phenomena related to harmonics of independent pulsation modes challenge the traditional understanding in this area. These discoveries serve as cornerstones for future research and advance nonlinear asteroseismology.

We present an analysis of high-resolution far-ultraviolet archival spectra obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope of the star HD 75309, which probes high-velocity shocked gas in the Vela supernova remnant (SNR). We examine high-velocity features from intrinsically strong absorption lines of O I, Si II, Si II*, C II, C II*, and Si III. We also detect high-velocity components in the N V doublet and compare these features to observations of high-velocity O VI absorption, available from archival Far Ultraviolet Spectroscopic Explorer data. Kinetic temperatures are derived from the observed fractional abundances of the various ions, while gas densities and thermal pressures are obtained from the relative populations in excited fine-structure levels of C II and Si II. Our results indicate that the highly ionized species at high velocity probe gas in a region immediately behind a shock driven into an interstellar cloud, while the lower ionization species trace material further downstream in the cooling region of the post-shock flow. Low velocity N V and O VI absorption may trace gas in a conductive boundary layer between the unshocked portion of the cloud and the hot X-ray emitting intercloud medium. Temporal variations in high velocity Ca II absorption features observed toward HD 75309 further confirm the highly inhomogeneous nature of the interstellar medium interacting with the Vela SNR.

We present observations and modeling results of the propagation and impact at Earth of a high-latitude, extended filament channel eruption that commenced on 2015 July 9. The coronal mass ejection (CME) that resulted from the filament eruption was associated with a moderate disturbance at Earth. This event could be classified as a so-called "problem storm" because it lacked the usual solar signatures that are characteristic of large, energetic, Earth-directed CMEs that often result in significant geoeffective impacts. We use solar observations to constrain the initial parameters and therefore to model the propagation of the 2015 July 9 eruption from the solar corona up to Earth using 3D magnetohydrodynamic heliospheric simulations with three different configurations of the modeled CME. We find the best match between observed and modeled arrival at Earth for the simulation run that features a toroidal flux rope structure of the CME ejecta, but caution that different approaches may be more or less useful depending on the CME-observer geometry when evaluating the space weather impact of eruptions that are extreme in terms of their large size and high degree of asymmetry. We discuss our results in the context of both advancing our understanding of the physics of CME evolution and future improvements to space weather forecasting.

We present the first reliable determination of the orbital period of the recurrent nova V2487 Oph (Nova Oph 1998). We derived a value of $0.753 \pm 0.016$ d ($18.1 \pm 0.4$ h) from the radial velocity curve of the intense He II $\lambda$4686 emission line as detected in time-series X-shooter spectra. The orbital period is significantly shorter than earlier claims, but it makes V2487 Oph one of the longest period cataclysmic variables known. The spectrum of V2487 Oph is prolific in broad Balmer absorptions that resemble a white dwarf spectrum. However, we show that they come from the accretion disc viewed at low inclination. Although highly speculative, the analysis of the radial velocity curves provides a binary mass ratio $q \approx 0.16$ and a donor star mass $M_2 \approx 0.21$ M$_\odot$, assuming the reported white dwarf mass $M_1 = 1.35$ M$_\odot$. A subgiant M-type star is tentatively suggested as the donor star. We were lucky to inadvertently take some of the spectra when V2487 Oph was in a flare state. During the flare, we detected high-velocity emission in the Balmer and He II $\lambda$4686 lines exceeding $-2000$ km s$^{-1}$ at close to orbital phase 0.4. Receding emission up to $1200$ km s$^{-1}$ at about phase 0.3 is also observed. The similarities with the magnetic cataclysmic variables may point to magnetic accretion on to the white dwarf during the repeating flares.

Eclipse timing variations (ETV) have been a successful tool for detecting circumbinary companions to eclipsing binaries (EB). While TESS and Kepler have been prolific for ETV searches, they sometimes can be limited by time and sky coverage which can be addressed by specialised ground-based ETV surveys. We present the initial results from the Solaris photometric survey which uses four 0.5m robotic telescopes in the southern hemisphere to look for circumbinary companions. We present the method of light curve extraction, detrending, and EB modelling using the observations from the Solaris network. Using these light curves we extract precise eclipse timing for 7 EB and look for companions using a Lomb-Scargle periodogram search. We find two possible periodic signals for the target GSC 08814-01026. With the system having strong activity, we check for the feasibility of orbital solutions at these two periods. We find that the 245 +/- 1 d period is due to an M-dwarf mass companion. This makes GSC 08814-01026 a candidate compact hierarchical triple system. The other periodic signal at 146 +/- 1 d is an artefact of stellar activity.

We compute the classical tree-level five-point amplitude for the two-to-two scattering of spinning celestial objects with the emission of a graviton. Using this five-point amplitude, we then turn to the computation of the leading-order time-domain gravitational waveform. The method we describe is suitable for arbitrary values of classical spin of Kerr black holes and does not require any expansion in powers of the spin. In this paper we illustrate it in the simpler case of the scattering of one Kerr and one Schwarzschild black hole. An important ingredient of our calculation is a novel form of the Compton amplitude with spinning particles including contact terms derived from matching to black-hole perturbation theory calculations. This ensures that our waveform is valid up to at least fourth order in the spin. Our method can be applied immediately to generate improved waveforms once higher-order contact terms in the Compton amplitude become available. Finally, we show the formula for the gravitational memory to all orders in the spin, which is in agreement with our results.

We present MDIRK: a Multifluid second-order Diagonally-Implicit Runge-Kutta method to study momentum transfer between gas and an arbitrary number ($N$) of dust species. The method integrates the equations of hydrodynamics with an Implicit Explicit (IMEX) scheme and solves the stiff source term in the momentum equation with a diagonally-implicit asymptotically stable Runge-Kutta method (DIRK). In particular, DIRK admits a simple analytical solution that can be evaluated with $\mathcal{O}(N)$ operations, instead of standard matrix inversion, which is $\mathcal{O}(N)^3$. Therefore the analytical solution significantly reduces the computational cost of the multifluid method, making it suitable for studying the dynamics of systems with particle-size distributions. We demonstrate that the method conserves momentum to machine precision and converges to the correct equilibrium solution with constant external acceleration. To validate our numerical method we present a series of simple hydrodynamic tests, including damping of sound waves, dusty shocks, a multi-fluid dusty Jeans instability, and a steady-state gas-dust drift calculation. The simplicity of MDIRK lays the groundwork to build fast high-order asymptotically stable multifluid methods.

In general relativity, when two black holes merge they produce a rotating (Kerr) black hole remnant. According to perturbation theory, the remnant emits "ringdown" radiation: a superposition of exponentials with characteristic complex frequencies that depend only on the remnant's mass and spin. While the goal of the black hole spectroscopy program is to measure the quasinormal mode frequencies, a knowledge of their amplitudes and phases is equally important to determine which modes are detectable, and possibly to perform additional consistency checks. Unlike the complex frequencies, the amplitudes and phases depend on the properties of the binary progenitors, such as the binary mass ratio and component spins. In this paper we develop a fitting algorithm designed to reliably identify the modes present in numerical simulations and to extract their amplitudes and phases. We apply the algorithm to over 500 binary black hole simulations from the public SXS numerical relativity simulation catalog, and we present fitting formulas for the resulting mode amplitudes and phases as functions of the properties of the progenitors. Crucially, our algorithm allows for the extraction of not only prograde fundamental modes and overtones, but also retrograde modes and second-order modes. We unveil interesting relations for the amplitude ratios of different modes. The fitting code and interactive versions of some of the plots are publicly available. The results presented in this paper can be updated as more and better simulations become available.

In this paper, we explore the chaotic signatures of the geodesic dynamics for particles moving in the slowly rotating Hartle-Thorne spacetime; an approximate solution of vacuum Einstein field equations describing the exterior of a massive, deformed, and slowly rotating compact object. We employ the numerical study to examine the geodesics of prolate and oblate deformations for generic orbits and find the plateaus of the rotation curve, which are associated with the existence of Birkhoff islands in the Poincare surface of the section, where the ratio of the radial and polar frequency of geodesics remains constant throughout the island. We investigate various phase space structures, including hyperbolic points and chaotic regions in the neighborhood of resonant islands. Moreover, chaotic behavior is observed to be governed by the stickiness phenomenon, where chaotic orbits remain attached to stable ones for an extended duration before eventually diverging and are attracted toward the surface of the neutron star. The precision of the numerical integration used to simulate the particle's trajectories plays a crucial role in the structures of the Poincare surface of the section. We present a comparison of several efficient structure-preserving numerical schemes of order four applied to the considered non-integrable dynamical system and we investigate which schemes possess the canonical property of the Hamiltonian flow. Among the class of non-symplectic integrators, we employ the explicit Runge-Kutta method and explicit general linear method with a standard projection technique to project the numerical solution onto the desired manifold. The projection scheme admits the integration without any drift from the desired manifold and is computationally cost-effective. We are concerned with two crucial aspects -- long-term behaviour and CPU time consumption.

In our previous work, we have explored quantum gravity induced entanglement of mass (QGEM) in curved spacetime, observing entanglement formation between particles moving along geodesics in a Schwarzschild spacetime background. We find that long interaction time induces entanglement, even for particles with microscopic mass, addressing decoherence concerns. In this work, we build upon our previous work by extending our investigation to a time-dependent spacetime. Specifically, we explore the entanglement induced by the mutual gravitation of massive particles in the Friedmann-Lema\^itre-Robertson-Walker(FLRW) universe. Through calculations of the phase variation and the QGEM spectrum, our proposed scheme offers a potential method for observing the formation of entanglement caused by the quantum gravity of massive particles as they propagate in the FLRW universe. Consequently, our research provides fresh insights into the field of entanglement in cosmology.

In order to study the validity of analytical formulas used in the calculation of characteristic physical quantities related to vacuum bubbles, we conduct several numerical simulations of bubble kinematics in the context of cosmological first-order phase transitions to determine potentially existing systematic uncertainties. By comparing with the analytical results, we obtain the following observations: (1) For the total number of bubbles, there is a 10% discrepancy between the values from simulations and from analytical prediction; (2) For the false vacuum fraction, the difference between the results from simulations and from analytical prediction is small, which, however, plays a crucial role in explaining the discrepancy observed in the total number of bubbles; (3) The bubble lifetime distribution obtained from the simulations deviates from the exponential distribution and is not obviously influenced by different nucleation rates; (4) These differences propagate into the final gravitational waves spectra, which we calculate with the sound shell model for the usually dominant contribution from sound waves, and find that the bubble number deviation enhances the peak value in the gravitational wave spectra, while the deviation in the lifetime distribution suppresses the peak value.

The f\'eeton is the gauge boson of the $U(1)_{B-L}$ gauge theory. If the gauge coupling constant is extremely small, it becomes a candidate for dark matter. We show that its decay to a pair of electron and positron explains the observed Galactic 511-keV gamma-ray excess in a consistent manner. This f\'eeton dark matter decays mainly into pairs of neutrino and anti-neutrino. Future low-energy experiments with improved directional capability make it possible to capture those neutrino signals. The seesaw-motivated parameter space predicts a relatively short f\'eeton lifetime comparable to the current cosmological constraint.

The next-generation water Cherenkov Hyper-Kamiokande detector will be able to detect thousands of neutrino events from a galactic Supernova explosion via Inverse Beta Decay processes followed by neutron capture on Gadolinium. This superb statistics provides a unique window to set bounds on neutrino properties, as its mass and lifetime. We shall explore the capabilities of such a future detector, constraining the former two properties via the time delay and the flux suppression induced in the Supernovae neutrino time and energy spectra. Special attention will be devoted to the statistically sub-dominant elastic scattering induced events, normally neglected, which can substantially improve the neutrino mass bound via time delays. When allowing for a invisible decaying scenario, the $95\%~$C.L. lower bound on $\tau/m$ is almost one order of magnitude better than the one found with SN1987A neutrino events. Simultaneous limits can be set on both $m_\nu$ and $\tau_{\nu}$, combining the neutrino flux suppression with the time-delay signature: the best constrained lifetime is that of $\nu_1$, which has the richest electronic component. We find $\tau_{\nu_1}\gtrsim 4\times 10^5~$s at $95\%~$C.L. The tightest $95\%~$C.L. bound on the neutrino mass we find is $0.34~$eV, which is not only competitive with the tightest neutrino mass limits nowadays, but also comparable to future laboratory direct mass searches. Both mass and lifetime limits are independent on the mass ordering, which makes our results very robust and relevant.

The latest caldera-forming eruption of Okmok volcano, Alaska, had a global atmospheric impact with tephra deposits found in distant Arctic ice cores and a sulfate signal found in Antarctic ice cores. The associated large-scale climate cooling was driven by the amount of sulfur injected into the stratosphere during the climactic phase of the eruption. This phase was dominated by pyroclastic density currents, which have complex emplacement dynamics precluding direct estimates of the sulfur stratospheric load. We simulated the dynamics of this climactic phase with the two-phase flow model MFIX-TFM under axisymmetric conditions with several combinations of injection mass flux, emission duration, and topography. Results suggest that a steady mass flux of $8.6-28\times 10^9$ kg/s is consistent with field observations. Stratospheric injections occur in pulses issued from 1) the central plume initially rising above the caldera center, 2) successive co-ignimbrite clouds caused by the encounter of the pyroclastic density currents with topography, and 3) the buoyant lift-off of dilute parts of the currents at the end of the eruption. Overall, 2.5 to 25% of the emitted volcanic gas reaches the stratosphere if the mass flux at the vent is steady. A fluctuating emission rate or an efficient final lift-off due to seawater interaction were unlikely to have increased this loading. Combined with petrological estimates of the degassed S, our results suggest that the eruption emitted 46.5-60.4 Tg S into the troposphere and injected 1.6-15.5 Tg S into the stratosphere, which controlled the atmospheric forcing and the subsequent climate response.

A simple and clear method is proposed to calculate the averaged motion of the apsis line in the Moon orbit. The obtained result is $3^{\circ}1'12''$ for the starry period of the Moon revolution around the Earth or $40^{\circ}22'48''$ per year. The modern observed value of the latter quantity is $40^{\circ}41'$ per year. In "Principia" Newton derived $1^{\circ}31'28''$ for the Moon month and $20^{\circ}12''$ per year. That is approximately two times less than the observable values. Unlike the Newton approach we use a simple and obvious averaging of the Sun disturbing force for the starry period of the Moon revolution around the Earth. The applicability of the obtained formulae to satellites of other planets and to the planets themselves is grounded. Comparing Newton's calculation with our method we reveal the reason, rather convincing, that brings Newton to inadequate result.

In this paper, we construct a viable model for a GeV scale self-interacting dark matter (DM), where the DM was thermally produced in the early universe. In this model, a new vector-like fermion with a dark charge under the $U(1)_{D}$ gauge symmetry serves as a secluded WIMP DM and it can dominantly annihilate into the light dark gauge boson and singlet scalar through the dark gauge interaction. Also, the self-interaction of DM is induced by the light dark gauge boson via the same gauge interaction. In addition to these particles, we further introduce two Weyl fermions and a doublet scalar, by which the dark gauge boson produced from $s$-wave DM annihilations can mostly decay into active neutrinos after the dark symmetry breaking such that the CMB bound on the DM with low masses can be eluded. In order to have a common parameter region to explain the observed relic abundance and self-interaction of DM, we also study this model in a non-standard cosmological evolution, where the cosmic expansion driven by a new field species is faster than the standard radiation-dominated universe during the frozen time of DM. Reversely, one can also use the self-interacting nature of light thermal DM to examine the non-standard cosmological history of the universe.

The recent start of the fourth observing run of the LIGO-Virgo-KAGRA (LVK) collaboration has reopened the hunt for gravitational-wave (GW) signals, with one compact-binary-coalescence (CBC) signal expected to be observed every few days. Among the signals that could be detected for the first time there is the stochastic gravitational-wave background (SGWB) from the superposition of unresolvable GW signals that cannot be detected individually. In fact, multiple SGWBs are likely to arise given the variety of sources, making it crucial to identify the dominant components and assess their origin. However, most search methods with ground-based detectors assume the presence of one SGWB component at a time, which could lead to biased results in estimating its spectral shape if multiple SGWBs exist. Therefore, a joint estimate of the components is necessary. In this work, we adapt such an approach and analyse the data from the first three LVK observing runs, searching for a multi-component isotropic SGWB. We do not find evidence for any SGWB and establish upper limits on the dimensionless energy parameter $\Omega_{\rm gw}(f)$ at 25 Hz for five different power-law spectral indices, $\alpha = 0, \, 2/3,\, 2,\, 3,\, 4$, jointly. For the spectral indices $\alpha = 2/3,\, 2, \, 4$, corresponding to astrophysical SGWBs from CBCs, r-mode instabilities in young rotating neutron stars, and magnetars, we draw further astrophysical implications by constraining the ensemble parameters $K_{\rm CBC}, \, K_{\rm r-modes}, \, K_{\rm magnetars}$, defined in the main text.

We use the Trans-Planckian Censorship Conjecture (TCC) to constrain the decay constants $f$ characterizing a set of N identical axion-like fields with cosine potentials, improving upon the precision of other Swampland conjectures and existing string-theoretic arguments. We find that consistency with the TCC requires any such set of axion-like fields to satisfy $f\sqrt{N} \lesssim 0.6M_{pl}$, where $M_{pl}$ is the reduced Planck mass. We show that this bound makes models of axion-driven inflation incapable of simultaneously producing the required number of e-foldings and the observed scalar spectral tilt. In contrast, we find that models of axion quintessence can be simultaneously compatible with the TCC and observational data, provided that the axions' initial field values are set near the maxima of their potentials to within roughly $\pm \frac{\pi}{5}f$.