Papers for Friday, Jan 10 2025

High-energy collisions at the high-luminosity Large Hadron Collider (HL-LHC) will generate a vast flux of particles along the beam collision axis, a region not accessible by current LHC experiments. The study of multi-particle production in the far-forward region is especially important for astroparticle physics. High-energy cosmic rays create extensive air showers (EAS) in the atmosphere, driven by hadron-ion collisions in the non-perturbative QCD regime. Therefore, understanding high-energy hadronic interactions in the forward region is crucial for interpreting EAS data and estimating backgrounds for searches of astrophysical neutrinos, among other applications. The Forward Physics Facility (FPF) is a proposal to construct a new underground cavern at the HL-LHC, hosting various far-forward experiments designed to detect particles outside the current LHC acceptance. We will outline the current plans for the FPF and highlight its synergies with astroparticle physics. Specifically, we will discuss how FPF measurements will enhance the modeling of high-energy interactions in the atmosphere, helping to reduce the associated uncertainties in multi-messenger astrophysics.

The proposed Habitable Worlds Observatory is intended to observe the atmospheres of nearby terrestrial exoplanets with a resolution greater than that of any previous instrument. While these observations present a substantial opportunity for astrobiology, they also incur the risk of false positives and false negatives. Here, we explore the use of systems science (in the form of network theory and thermochemical kinetics) to mitigate these risks, and briefly describe the technical specifications HWO would require in order to use these methodologies.

In this article we propose an original classification method for unobscured imaging systems unfolded in two dimensions. This classification is based on a study of off-axis properties, and relies on topology and algorithm of real algebraic geometry to find at least one instance by connected component of a semialgebraic set. Our corresponding nomenclature provides intrinsic information about the system, in terms of geometry and manufacturability. The proposed systems for each name of the nomenclature, can be used as starting points for parallel optimizations, allowing for a much more comprehensive search of an unobscured solution, given a set of specifications. We exemplify our method on three and four mirrors imaging systems.

Low-field magnetars have dipolar magnetic fields that are 10-100 times weaker than the threshold, $B \gtrsim 10^{14}$ G, used to define classical magnetars, yet they produce similar X-ray bursts and outbursts. Using the first direct numerical simulations of magneto-thermal evolution starting from a dynamo-generated magnetic field, we show that the low-field magnetars can be produced as a result of a Tayler--Spruit dynamo inside the proto-neutron star. We find that these simulations naturally explain key characteristics of low-field magnetars: (1) weak ($\lesssim 10^{13}$ G) dipolar magnetic fields, (2) strong small-scale fields, and (3) magnetically induced crustal failures producing X-ray bursts. These findings suggest two distinct formation channels for classical and low-field magnetars, potentially linked to different dynamo mechanisms.

We provide a perturbative effective field theory (EFT) description for anisotropic (redshift-space) correlations between the Lyman alpha forest and a generic biased tracer of matter, which could be represented by quasars, high-redshift galaxies, or dark matter halos. We compute one-loop EFT power spectrum predictions for the combined analysis of the Lyman alpha and biased tracers' data and test them on the publicly available high fidelity Sherwood simulations. We use massive and light dark matter halos at redshift $z=2.8$ as proxies for quasars and high-redshift galaxies, respectively. In both cases, we demonstrate that our EFT model can consistently describe the complete data vector consisting of the Lyman alpha forest auto spectrum, the halo auto spectrum, and the Lyman alpha -- halo cross spectrum. We show that the addition of cross-correlations significantly sharpens constraints on EFT parameters of the Lyman alpha forest and halos. In the combined analysis, our EFT model fits the simulated cross-spectra with a percent level accuracy at $k_{\rm max}= 1~h$Mpc$^{-1}$, which represents a significant improvement over previous analytical models. Thus, our work provides precision theoretical tools for full-shape analyses of Lyman alpha - quasar cross-correlations with ongoing and upcoming spectroscopic surveys.

We present deep Magellan$+$Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultra-faint satellites. Our data reach $\sim2-3$ magnitudes deeper than the discovery data from the DECam Local Volume Exploration (DELVE) Survey. We use these data to constrain their distances, structural properties (e.g., half-light radii, ellipticity, and position angle), and luminosities. We investigate whether these systems show signs of tidal disturbance, and identify new potential member stars using Gaia EDR3. Our deep color-magnitude diagrams show that Cen I and Eri IV are consistent with an old ($\tau\sim 13.0$ Gyr) and metal-poor ($\text{[Fe/H]}\le-2.2$) stellar population. We find Cen I to have a half-light radius of $r_{h}=2.60\pm0.30'$ ($90.6\pm11$ pc), an ellipticity of $\epsilon=0.36\pm0.05$, a distance of $D=119.8\pm4.1$ kpc ($m-M=20.39\pm0.08$ mag), and an absolute magnitude of $M_{V}=-5.39\pm0.19$. Similarly, Eri IV has $r_{h}=3.24\pm0.48'$ ($65.9\pm10$ pc), $\epsilon=0.26\pm0.09$, $D=69.9\pm3.6$ kpc ($m-M=19.22\pm0.11$ mag), and $M_{V}=-3.55\pm0.24$. These systems occupy a space on the size-luminosity plane consistent with other known Milky Way dwarf galaxies which supports the findings from our previous spectroscopic follow-up. Cen I has a well-defined morphology which lacks any clear evidence of tidal disruption, whereas Eri IV hosts a significant extended feature with multiple possible interpretations.

Variable $\gamma$-ray flares upto minute timescales reflect extreme particle acceleration sites. However, for high-redshift blazars, the detection of such rapid variations remains limited by current telescope sensitivities. Gravitationally lensed blazars serve as powerful tools to probe $\gamma$-ray production zones in distant sources, with time delays between lensed signals providing crucial insights into the spatial distribution of emission regions relative to the lens's mass-weighted center. We have utilized 15 years of Fermi-LAT $\gamma$-ray data from direction of PKS 1830$-$211 to understand the origin of flaring high-energy production zone at varying flux states. To efficiently estimate the (lensed) time delay, we used a machine learning-based tool - the Gaussian Process regression algorithm, in addition to - Autocorrelation function and Double power spectrum. We found a consistent time delay across all flaring activity states, indicating a similar location for the $\gamma$-ray emission zone, possibly within the radio core. The estimated time delay of approximately 20 days for the five flaring epochs was significantly shorter than previously estimated radio delays. This suggests that the $\gamma$-ray emission zone is closer to the central engine, in contrast to the radio emission zone, which is expected to be much farther away. A linear relationship between lag and magnification has been observed in the identified source and echo flares. Our results suggest that the $\gamma$-ray emission zone originates from similar regions away from the site of radio dissipation.

In binary star systems, mass transfer can spin up the accretor, possibly leading to efficient chemical mixing and chemically quasi-homogeneous evolution (CHE). Here, we explore the effects of accretion-induced CHE on both stellar populations and their compact binary remnants with the state-of-the-art population synthesis code SEVN. We find that CHE efficiently enhances the formation of Wolf-Rayet stars (WRs) from secondary stars, which are spun-up by accretion, while simultaneously preventing their evolution into red supergiant stars (RSGs). Including CHE in our models increases the fraction of WRs in our stellar sample by nearly a factor of $\approx3$ at low metallicity ($Z=0.001$). WRs formed through CHE are, on average, more massive and luminous than those formed without CHE. Most WRs formed via CHE end their life as black holes. As a direct consequence, the CHE mechanism enhances the formation of binary black holes (BBHs) and black hole-neutron star (BHNS) systems, while simultaneously quenching the production of binary neutron stars (BNSs). However, CHE significantly quenches the merger rate of BBHs, BHNSs and BNSs at low metallicity ($Z\leq{}0.004$), because most binary compact objects formed via CHE have large orbital periods. For instance, the number of BBH and BHNS mergers decreases by one order of magnitude at $Z=0.004$ in the CHE model compared to the standard scenario. Finally, we find that secondary stars experiencing CHE frequently produce the most massive compact object in the binary system. In BHNSs, this implies that the black hole progenitor is the secondary star. Conversely, BBHs formed through accretion-induced CHE likely have asymmetric black hole components, but only a negligible fraction of these asymmetric systems ultimately merge within an Hubble time.

Geodetic and astrometric VLBI has entered a new era with the implementation of the VLBI Global Observing System (VGOS). These broadband and dual linear polarization observations aim at an accuracy of station coordinates of 1 mm and a reference frame stability of 0.1 mm/year. Although the extended brightness distribution of many of the radio-loud active galactic nuclei observed during geodetic VLBI sessions is resolved by the interferometer, the established processing chain still treats these objects as point sources. We investigate the impact of source structure on the visibility level and develop tools to remove the structure from the visibility data, right after correlation. Here we present our approach and show results obtained from observational VGOS data.

We present a study of the size growth of the red sequence between $0.5<z<3,$ tracing the evolution of quiescent galaxies in both effective half-light and half-mass radii using multi-wavelength JWST/NIRCam imaging provided by the PRIMER survey. Half-light radii are measured from imaging in 6 different filters for 455 quiescent galaxies with log($M_*/M_{\odot}$)$>10$, whereas half-mass radii are derived from the F444W profiles together with the F277W-F444W color-$M_*$/L relation. We investigate the dependence of the ratio $r_{e, \mathrm{mass}}/r_{e, \mathrm{light}}$ on redshift, stellar mass, and the wavelength used to measure $r_{e, \mathrm{light}}$, also separating the sample into younger and older quiescent galaxies. Our data demonstrate that rest-frame infrared sizes accurately trace mass-weighted sizes while sizes measured at rest-frame optical wavelengths (0.5-0.7$\mu$m) are 0.1-0.2 dex larger, with only minor variations in redshift. We find that the average size of young quiescent galaxies agrees with that of old quiescent galaxies at intermediate masses, $10<$log($M_*/M_{\odot}$)$<11$, within their respective uncertainties in all observed-frame half-light, rest-frame half-light and half-mass radius measurements. At face value, our results point to a combination of progenitor bias and minor mergers driving the size growth of intermediate-mass quiescent galaxies at $0.5<z<3$. Our results further indicate that the varying contributions to the general quiescent population by young and old quiescent galaxies can mimic evolution in redshift.

Subject of this paper is the simplification of Markov chain Monte Carlo sampling as used in Bayesian statistical inference by means of normalising flows, a machine learning method which is able to construct an invertible and differentiable transformation between Gaussian and non-Gaussian random distributions. We use normalising flows to compute Bayesian partition functions for non-Gaussian distributions and show how normalising flows can be employed in finding analytical expressions for posterior distributions beyond the Gaussian limit. Flows offer advantages for the numerical evaluation of the partition function itself, as well as for cumulants and for the information entropy. We demonstrate how normalising flows in conjunction with Bayes partitions can be used in inference problems in cosmology and apply them to the posterior distribution for the matter density $\Omega_m$ and a dark energy equation of state parameter $w_0$ on the basis of supernova data.

A variety of high-energy astrophysical phenomena are powered by the release -- via magnetic reconnection -- of the energy stored in oppositely directed fields. Single-fluid resistive magnetohydrodynamic (MHD) simulations with uniform resistivity yield dissipation rates that are much lower (by nearly one order of magnitude) than equivalent kinetic calculations. Reconnection-driven phenomena could be accordingly modeled in resistive MHD employing a non-uniform, ``effective'' resistivity informed by kinetic calculations. In this work, we analyze a suite of fully kinetic particle-in-cell (PIC) simulations of relativistic pair-plasma reconnection -- where the magnetic energy is greater than the rest mass energy -- for different strengths of the guide field orthogonal to the alternating component. We extract an empirical prescription for the effective resistivity, $\eta_{\mathrm{eff}} = \alpha B_0 \mathbf{|J|}^p / \left(|\mathbf{J}|^{p+1}+\left(e n_t c\right)^{p+1}\right)$, where $B_0$ is the reconnecting magnetic field strength, $\bf J$ is the current density, $n_t$ the lab-frame total number density, $e$ the elementary charge, and $c$ the speed of light. The guide field dependence is encoded in $\alpha$ and $p$, which we fit to PIC data. This resistivity formulation -- which relies only on single-fluid MHD quantities -- successfully reproduces the spatial structure and strength of nonideal electric fields, and thus provides a promising strategy for enhancing the reconnection rate in resistive MHD simulations.

Because of the continuous variations in mass, metallicity, and opacity, dwarf stars are distributed along the main sequence on optical and near-IR color-magnitude diagrams following a smooth polynomial. In this study of utilizing a catalog of cross-matched GALEX and Gaia sources, we identify two distinct populations of M dwarfs in the near-ultraviolet (NUV) band on the $M_{NUV}$ vs. $M_G$ diagram. We also reveal a pronounced increase in the number of stars exhibiting high NUV fluxes near the spectral type M2 or $M_G\sim9.4$, coinciding with the $H_2$ formation in the atmosphere to improve the energy transportation at the surface. This suggests that certain yet-to-be-understood stellar mechanisms drive heightened activity in the NUV band around the effective temperature of M2 and later types of M dwarfs. Through examination of archival Hubble Space Telescope spectra, we show that Fe II line forests at $\sim$2400A and 2800A dominate the spectral features in the GALEX NUV bandpass, contributing to the observed excess fluxes at a given mass between the two populations. Additionally, our investigation indicates that fast rotators and young stars likely increase brightness in the NUV band, but not all stars with bright NUV fluxes are fast rotators or young stars.

Joint analysis of position measurements and radial velocities of six triple stellar systems is conducted to determine their inner and/or outer orbits. Accumulation of such data is needed to study the architecture of stellar hierarchies and its relation to the formation mechanisms. The inner periods in the six systems (HIP 11783, 64836, 72423, 84720, 89234, and 105404) range from 0.5 days to 44 yr. The shortest outer period of 3.34 yr is found in the compact triple HIP~105404 (BS Ind). The resolved triple system HIP 64836 has comparable inner and outer periods (5 and 30 yr), placing it near the limit of dynamical stability, while its quasi-circular and coplanar orbits suggest a 1:6 mean motion resonance. The periods in HIP 89234 (44 and ~450 yr) are also comparable, but the mutual orbit inclination is large, 54 degrees. Masses of the components are estimated and each system is discussed individually.

The solar cycle is a complex phenomenon. To comprehensively understand it, we have to study various tracers. The most important component of this complex is the solar dynamo, which is understood as self-excitation of the solar magnetic field in the form of traveling waves somewhere in the convection zone. Along with the solar dynamo, the formation of the solar cycle involves other processes that are associated with the dynamo but are not its necessary part. We give a review of such phenomena that have not yet been explained in terms of dynamo theory. We consider the manifestations of the solar cycle in harmonics of the solar large-scale surface magnetic field, including zonal, sectorial, and tesseral harmonics; analyze their contribution to magnetic energy; and identify phases of the activity cycle using harmonics of different types of symmetry. The universal magnetic scenario of a solar activity cycle does not depend on its number and height. At the beginning of the cycle on the photosphere, the zonal harmonics account for 37-42% of the total energy (not 100%, as assumed in simplified descriptions). Sectorial harmonics do not disappear at all but account for 5-10% of the total energy. At this stage, the greatest energy (about 40%) is contained in the tesseral harmonics. As the cycle develops, the relative energy of zonal harmonics gradually decreases, reaching a minimum of 15-18% immediately before the onset of the sunspot maximum. The relative energy of sectorial harmonics increases and reaches a maximum (60-65%) somewhat later than the calendar date of the sunspot maximum. A particular feature of the tesseral harmonics is that their relative energy index changes in a much narrower range and never falls below 40% even at the cycle minimum. This is due to active regions and nonglobal magnetic fields. It is possible that tesseral harmonics are formed in shallow subphotospheric layers.

Photoevaporation in exoplanet atmospheres is thought to contribute to the shaping of the small planet radius valley. Escaping atmospheres have been detected in transmission across a variety of exoplanet types, from hot Jupiters to mini-Neptunes. However, no work has yet considered whether outflows might also be detectable in emission. We introduce pyTPCI, a new, open-source self-consistent 1D radiative-hydrodynamics code that is an improved version of The PLUTO-CLOUDY Interface. We use pyTPCI to model seven exoplanets (HD 189733b, HD 209458b, WASP-69b, WASP-107b, TOI-1430b, TOI-560b, and HAT-P-32b) at varying metallicities and compute their emission spectra to investigate their detectability across a variety of spectral lines. We calculate the eclipse depths and signal-to-noise ratios (SNR) of these lines for a 10m class telescope with a high-resolution spectrograph, taking into account appropriate line broadening mechanisms. We show that the most detectable spectral lines tend to be the 589 nm Na I doublet and the 1083 nm metastable helium triplet. Halpha and Mg I 457 nm are moderately strong for some planets at some metallicities, but they are almost always optically thin, so some of their emission may not be from the outflow. The planet with the highest-flux, highest-eclipse-depth, and highest-SNR lines is HD 189733b, with a Na I eclipse depth of 410 ppm and SNR of 2.4 per eclipse, and a He* eclipse depth of 170 ppm and SNR of 1.3. These signals would be marginally detectable with Keck if 3-10 eclipses were observed, assuming (over-optimistically) photon limited observations.

M dwarfs are the most common stars in the galaxy, with long lifespans, a high occurrence rate of rocky planets, and close-in habitable zones. However, high stellar activity in the form of frequent flaring and any associated coronal mass ejections may drive atmospheric escape with the bombardment of radiation and high-energy particles, drastically impacting the habitability of these systems. The stellar latitude where flares and coronal mass ejections occur determines the space weather that exoplanets are subject to, with high-energy particle events associated with equatorial flares producing significant atmospheric erosion. However, the flaring latitudes for M dwarfs remain largely unconstrained. To aid in the effort to locate these flaring regions we explore the applicability of flare occultations using optical photometry to identify the latitudes of flares. As a planet transits in front of an ongoing flare the timing and geometry of the transit can be used to constrain the latitude and longitude of the flare. We predict the probability of detecting an occultation for known transiting planets and eclipsing binaries. From this, we estimate 3-22 detectable occultations exist within the TESS primary mission photometry, with the majority occurring in eclipsing binary observations. To demonstrate this technique, we analyze a candidate flare occultation event for the eclipsing binary CM Draconis.

The Gaia optical astrometric mission has measured the precise positions of millions of objects in the sky, including extragalactic sources also observed by Very Long Baseline Interferometry (VLBI). In the recent Gaia EDR3 release, an effect of negative parallax with a magnitude of approximately -17 $\mu$as was reported, presumably due to technical reasons related to the relativistic delay model. A recent analysis of a 30-year set of geodetic VLBI data revealed a similar negative parallax with an amplitude of $-15.8 \pm 0.5$ $ \mu$as. Since both astrometric techniques, optical and radio, provide consistent estimates of this negative parallax, it is necessary to investigate the potential origin of this effect. We developed the extended group relativistic delay model to incorporate the additional parallactic effect for radio sources at distances less than 1 Mpc and found that the apparent annual signal might appear due the non-orthogonality of the fundamental axes, which are defined by the positions of the reference radio sources themselves. Unlike the conventional parallactic ellipse, the apparent annual effect in this case appears as a circular motion for all objects independently of their ecliptic latitude. The measured amplitude of this circular effect is within a range of 10-15 $\mu$as that is consistent with the ICRF3 stability of the fundamental axis. This annual circular effect could also arise if a Gödel-type cosmological metric were applied, suggesting that, in the future, this phenomenon could be used to indicate global cosmic rotation.

We present a detailed analysis of the long-duration GRB 241030A detected by {\it Swift}. Thanks to the rapid response of XRT and UVOT, the strongest part of the prompt emission of GRB 241030A has been well measured simultaneously from optical to hard X-ray band. The time-resolved WHITE band emission shows strong variability, largely tracing the activity of the prompt gamma-ray emission, may be produced by internal shocks too. The joint analysis of the XRT and BAT data reveals the presence of a thermal component with a temperature of a few keV, which can be interpreted as the photosphere radiation, and the upper limit of the Lorentz factor of this region is found to range between approximately 20 and 80. The time-resolved analysis of the initial U-band exposure data yields a very rapid rise ($ \sim t^{5.3}$) with a bright peak reaching 13.6 AB magnitude around 410 seconds, which is most likely attributed to the onset of the external shock emission. The richness and fineness of early observational data have made this burst a unique sample for studying the various radiation mechanisms of gamma-ray bursts.

Radio observations can provide crucial insight into the nature of a new abundant and mysterious population of dust-reddened active galactic nuclei (AGN) candidates discovered by the James Webb Space Telescope (JWST), including ``Little Red Dots" (LRDs). In this study, we search for radio bright sources in a large sample of $\sim$700 JWST discovered AGN candidates ($z\sim2-11$) in the 0.144-3 GHz frequency range, utilizing deep radio imaging in COSMOS, GOODS-N, and GOODS-S. Only one source is significantly detected in our radio surveys, which is PRIMER-COS 3866 at $z=4.66$. Its radio properties are consistent with both an AGN and star formation origin with a spectral index of $\alpha=-0.76^{+0.11}_{-0.09}$ and a radio-loudness of $R\approx0.5$. The derived brightness temperature limit of PRIMER-COS 3866 of $T_b \gtrsim 10^{3}$ K is too low to confirm its AGN nature. Our stacking results yield non-detections in all fields with the most constraining 3$\sigma$ limit $L_{1.3\text{GHz}} < 1.3\times10^{39}$ erg s$^{-1}$ (rms of $\sim$0.15 $\mu$Jy beam$^{-1}$ at $z_{\text{median}}=6.1$) obtained for photometrically selected AGN candidates in the COSMOS field. This result is still consistent with expectations from the empirical $L_X - L_{\text{H}\alpha}$ and $L_X - L_R$ correlations established for local AGN. We conclude that current radio observations have insufficient depth to claim JWST discovered AGN candidates are radio-weak. We project that future surveys carried out by the SKA and ngVLA should be able to obtain significant detections within a few hours, providing crucial measurements of their brightness temperature, which would allow for distinguishing between AGN and starburst-driven origins of this new abundant population.

Correlated behaviours between the radio emission and the X-ray emission in Galactic black hole X-ray binaries (BH XRBs) in the X-ray hard state are crucial to the understanding of disc-jet coupling of accreting black holes. The BH transient 4U 1543-47 went into outburst in 2021 following ~19 years of quiescence. We followed it up with ~weekly cadence with MeerKAT for about one year and a half until it faded into quiescence. Multi-epoch quasi-simultaneous MeerKAT and X-ray observations allowed us to trace the compact jet emission and its X-ray emission. In its hard spectral state across three orders of magnitude of X-ray luminosities above ~10$^{34}$ ergs/s, we found the correlation between radio and X-ray emission had a power-law index of 0.82$\pm$0.09, steeper than the canonical value of ~0.6 for BH XRBs. In addition, the radio vs. X-ray correlation shows a large range of the power-law normalization, with the maximum significantly larger than that obtained for most BH XRBs, indicating it can be particularly radio-bright and variable in the X-ray binary sample. The radio emission is unlikely diluted by discrete jet components. The observed peculiar radio-bright and variable behaviours provide the evidence for the relativistic effects of a variable Lorentz factor in the range between 1 and ~2 of the compact jet.

We present the first characterization of the statistical relationship between a large sample of novae in M31 and their progenitor stellar populations in the form of a delay time distribution. To this end, we leverage the spatially resolved stellar age distribution of the M31 disk derived from deep HST photometry by the Panchromatic Hubble Andromeda Treasury (PHAT) survey and a large catalog of novae in M31. Our delay time distribution has two statistically significant detections: one population of nova progenitors, ages between 2 and 3.2 Gyr, with an unnormalized rate of ($3.7^{+6.8}_{-3.5} \pm 2.1) \cdot 10^{-9}$ events / $M_{\odot}$, and another of ages between 7.9 Gyr and the age of the Universe with ($4.8^{+1.0}_{-0.9} \pm 0.2) \cdot 10^{-9}$ events / $M_{\odot}$ (uncertainties are statistical and systematic, respectively). Together with the upper limits we derive at other time bins, these detections are consistent with either a constant production efficiency or a higher production efficiency of novae at earlier delay times.

Early-type galaxies (ETGs) are reference systems to understand galaxy formation and evolution processes. The physics of their collapse and internal dynamics are codified in well-known scaling relations. Cosmological hydrodynamical simulations play an important role, providing insights into the 3D distribution of matter and galaxy formation mechanisms, as well as validating methods to infer the properties of real objects. In this work, we present the closest-to-reality sample of ETGs from the IllustrisTNG100-1 simulation, dubbed "virtual-ETGs," based on an observational-like algorithm that combines standard projected and three-dimensional galaxy structural parameters. We extract 2D photometric information by projecting the galaxies' light into three planes and modeling them via Sérsic profiles. Aperture velocity dispersions, corrected for softened central dynamics, are calculated along the line-of-sight orthogonal to the photometric projection plane. Central mass density profiles assume a power-law model, while 3D masses remain unmodified from the IllustrisTNG catalogue. The final catalogue includes $10121$ galaxies at redshifts $z \leq 0.1$. By comparing the virtual properties with observations, we find that the virtual-ETG scaling relations (e.g., size-mass, size-central surface brightness, and Faber-Jackson), central density slopes, and scaling relations among total density slopes and galaxy structural parameters are generally consistent with observations. We make the virtual-ETG publicly available for galaxy formation studies and plan to use this sample as a training set for machine learning tools to infer galaxy properties in future imaging and spectroscopic surveys.

Low-mass galaxies are the building blocks of massive galaxies in the framework of hierarchical structure formation. To enable detailed studies of galactic ecosystems in dwarf galaxies by spatially resolving different galactic components, we have carried out the Dwarf Galaxy Integral-field Survey (DGIS). This survey aims to acquire observations with spatial resolutions as high as 10 to 100 pc while maintaining reasonably high signal-to-noise ratios with VLT/MUSE and ANU-2.3m/WiFeS. The whole sample will be composed of 65 dwarf galaxies with $M_{\rm \ast}$ $<$ 10$^{9}$ $\rm M_{\odot}$, selected from the Spitzer Local Volume Legacy Survey. The overall scientific goals include studying baryonic cycles in dwarf galaxies, searching for off-nuclear (intermediate)-massive black holes, and quantifying the inner density profiles of dark matter. In this work, we describe the sample selection, data reduction, and high-level data products. By integrating the spectra over the field of view for each galaxy, we obtained the integrated gas-phase metallicity and discussed its dependence on stellar mass and SFR. We find that the overall relation between metallicity and stellar mass of our DGIS nearly follows the extrapolation from the higher mass end. Its dispersion does not decrease by invoking the dependence on SFR.

Photometric surveys are good solutions for large-scale structure studies. The Baryon Acoustic Oscillations (BAO) benefit from photometric redshift survey observations due to faster coverage and a higher number of observed objects. In the present study, we use the Dark Energy Survey Year 3 catalog of Luminous Red Galaxies (LRG) to use the realistic galaxies' Probability Distribution Function (PDF) that describes each galaxy redshift to select samples and include in the fitting model as the input for the redshift uncertainty. We used four different photo-z estimators \texttt{ANNz2}, \texttt{BPZ}, \texttt{ENF}, and \texttt{DNF} to compare how they affect the BAO feature constraint, the catalogs called \texttt{Pz Cats}. Furthermore, for each algorithm, we selected two different samples according to the PDFs shape, one where the PDFs are nearly Gaussian and the other that chooses the least noisy PDFs in which the PDFs have one pronounced peak. We computed the correlation function $\xi_\perp(z_p)$ by getting the bin pairs transversal to each other using \texttt{CAMB}. The kernel window function is the $f(z|z_p)$ which is the selection of the PDF value when the photometric redshift is nearly the same as the spectroscopic redshift estimated by the matched spectroscopic sample. For compatible $z_{eff}$, We concluded that the shape of the galaxy redshift PDF could shift the BAO feature position either by including the PDF in the model or not We also learnt that, given the same spectroscopic sample, \texttt{ANNz2} is the best photo-z estimator for BAO analysis considering the realistic full probability distribution function of each galaxy.

$r$-mode oscillations in rotating neutron stars are a source of continuous gravitational radiation. We investigate the excitation of $r$-modes by the mechanical impact on the neutron star surface of stochastically accreted clumps of matter, assuming that the Chandrasekhar-Friedman-Schutz instability is not triggered. The star is idealised as a slowly-rotating, unmagnetised, one-component fluid with a barotropic equation of state in Newtonian gravity. It is found that the $r$-mode amplitude depends weakly on the equation of state but sensitively on the rotation frequency $\nu_{\rm s}$. The gravitational wave strain implicitly depends on the equation of state through the damping timescale. The root-mean-square strain is $h_{\rm rms} \approx 10^{-35} (\nu_{\rm s}/ 10 {\rm Hz})^{2} (R_*/10 {\rm km})^2 (\Delta t_{\rm acc}/1 {\rm yr})^{1/2} (f_{\rm acc}/1 {\rm kHz})^{-1/2} (\dot{M}/10^{-8} \text{M}_{\odot} \text{yr}^{-1}) (v/0.4c) (d/1 {\rm kpc})^{-1}$, which is comparable to the strain from $g$-, $p$- and $f$-modes excited by stochastic accretion, where $R_*$ is the radius of the star, $\Delta t_{\rm acc}$ is the uninterrupted duration of an accretion episode, $f_{\rm acc}$ is the mean clump impact frequency, $\dot{M}$ is the accretion rate, $v$ is the impact speed, and $d$ is the distance of the star from the Earth. An observational test is proposed, based on the temporal autocorrelation function of the gravitational wave signal, to discern whether the Chandrasekhar-Friedman-Schutz instability switches on and coexists with impact-excited $r$-modes before or during a gravitational wave observation.

We have conducted a widefield, wideband, snapshot survey using the Australian SKA Pathfinder (ASKAP) referred to as the Rapid ASKAP Continuum Survey (RACS). RACS covers $\approx$ 90% of the sky, with multiple observing epochs in three frequency bands sampling the ASKAP frequency range of 700 to 1800 MHz. This paper describes the third major epoch at 1655.5 MHz, RACS-high, and the subsequent imaging and catalogue data release. The RACS-high observations at 1655.5 MHz are otherwise similar to the previously released RACS-mid (at 1367.5 MHz), and were calibrated and imaged with minimal changes. From the 1493 images covering the sky up to declination $\approx$ +48$^\circ$, we present a catalogue of 2 677 509 radio sources. The catalogue is constructed from images with a median root-mean-square noise of $\approx$ 195 $\mu$Jy PSF$^{-1}$ (point-spread function) and a median angular resolution of 11.8" by 8.1". The overall reliability of the catalogue is estimated to be 99.18%, and we find a decrease in reliability as angular resolution improves. We estimate the brightness scale to be accurate to 10%, and the astrometric accuracy to be within $\approx$ 0.6" in right ascension and $\approx$ 0.7" in declination after correction of a systematic declination-dependent offset. All data products from RACS-high, including calibrated visibility datasets, images from individual observations, full-sensitivity mosaics, and the all-sky catalogue are available at the CSIRO ASKAP Science Data Archive.

The origin of cosmic rays (CRs) and how they propagate remain unclear. Studying the propagation of CRs in magnetohydrodynamic (MHD) turbulence can help to comprehend many open issues related to CR origin and the role of turbulent magnetic fields. To comprehend the phenomenon of slow diffusion in the near-source region, we study the interactions of CRs with the ambient turbulent magnetic field to reveal their universal laws. We numerically study the interactions of CRs with the ambient turbulent magnetic field, considering pulsar wind nebula as a general research case. Taking the magnetization parameter and turbulence spectral index as free parameters, together with radiative losses, we perform three group simulations to analyze the CR spectral, spatial distributions, and possible CR diffusion types. Our studies demonstrate that (1) CR energy density decays with both its effective radius and kinetic energy in the form of power-law distributions; (2) the morphology of the CR spatial distribution strongly depends on the properties of magnetic turbulence and the viewing angle; (3) CRs suffer a slow diffusion near the source and a fast/normal diffusion away from the source; (4) the existence of a power-law relationship between the averaged CR energy density and the magnetization parameter is independent of both CR energy and radiative losses; (5) radiative losses can suppress CR anisotropic diffusion and soften the power-law distribution of CR energy density. The distribution law established between turbulent magnetic fields and CRs presents an intrinsic property, providing a convenient way to understand complex astrophysical processes related to turbulence cascades.

We report the results of molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) towards two peculiar icy objects, which were discovered serendipitously by infrared spectroscopic survey of the Galactic plane with the AKARI satellite. Previous infrared observations have reported that both objects show deep ice and dust absorption features that are often seen in embedded young stellar objects (YSOs) or background stars sitting behind dense clouds, however, they are located neither in known star-forming regions nor in known dense clouds. Their infrared spectral energy distributions (SEDs) show a peak around 5 micron, which are incompatible with existing SED models of typical embedded YSOs. The present ALMA observations have detected compact emission of CO(3-2) and SiO(8-7) at the positions of the icy objects. The observed large column ratios of gas-phase SiO/CO (~10^-3) in both objects, as well as their broad line widths (8-14 km/s), imply that they are associated with shocked gas. Although a large dust extinction (Av ~100 mag) is expected from their deep dust/ice absorption, no dust continuum emission is detected, which would suggest a large beam dilution effect due to their compact source sizes. Their systemic velocities are clearly separated from the surrounding CO clouds, suggesting that they are isolated. The characteristics of their SEDs, the presence of deep dust/ice absorption features, compact source size, and SiO-dominated broad molecular line emission, cannot easily be accounted for by any of known interstellar ice-absorption sources. They may represent a previously unknown type of isolated icy objects.

The study of planetary nebulae (PNe) offers the opportunity of evaluating the efficiency of the dust production mechanism during the very late asymptotic giant branch (AGB) phases. We study the relationship between the properties of PNe, particularly the gas and dust content, with the mass and metallicity of the progenitor stars, to understand how dust production works in the late AGB phases, and to shed new light on the physical processes occurring to the stars and the material in their surroundings since the departure from the AGB until the PN phase. We consider a sample of 9 PNe in the Large Magellanic Cloud, 7 out of which characterized by the presence of carbonaceous dust, the remaining 2 with silicates. For these stars the masses and the metallicity of the progenitor stars were estimated. We combine results from stellar evolution and dust formation modelling with those coming from the analysis of the spectral energy distribution, to find the relation between the dust and gas mass of the PNe considered and the The physical properties of carbon-rich PNe are influenced by the mass of the progenitor star. Specifically, the dust-to-gas ratio in the nebula increases from 5x10^{-4}to 6x10^{-3} as the progenitor star's mass increases from approximately 0.9Msun to 2Msun. This change is partly influenced by the effective temperature of the PNe, and it occurs because higher-mass carbon stars are more efficient at producing dust. Consequently, as the progenitor's mass increases, the gas mass of the PNe decreases, since the larger amounts of dust lead to greater effects from radiation pressure, which pushes the gas outwards. No meaningful conclusions can be drawn by the study of the PNe with silicate-type dust, because the sub-sample is made up of 2 PNe only, one of which is almost dust-free.

We recently developed a Monte-Carlo method (GNC) that can simulate the dynamical evolution of a nuclear stellar cluster (NSC) with a massive black hole (MBH), where the two-body relaxations can be solved by the Fokker-Planck equations in energy and angular momentum space. Here we make a major update of GNC~ by integrating stellar potential and adiabatic invariant theory, so that we can study the self-consistent dynamics of NSCs with increasing mass of the MBH. We perform tests of the self-adaptation of cluster density due to MBH mass growth and Plummer core collapse, both finding consistent results with previous studies, the latter having a core collapse time of $\sim 17t_{\rm rh}$ by GNC, where $t_{\rm rh}$ is the time of half-mass relaxation. We use GNC~ to study the cosmological evolution of the properties of NSC and the mass of MBH assuming that the mass growth of the MBH is due to loss-cone accretion of stars (e.g., tidal disruption of stars) and stellar black holes, and compare the simulation results with the observations of NSCs in Milky-Way or near-by galaxies. Such scenario is possible to produce MBHs with mass $10^5\sim 10^7\,M_\odot$ for NSCs with stellar mass of $10^6\sim 10^9\,M_\odot$. In Milky-Way's NSC, to grow MBH up to $4\times 10^6\,M_\odot$, its size needs to be $\sim 1.7$ times more compact in early universe than the current value. MBHs with current masses $>6\times 10^{7}\,M_\odot$ seem difficult to explain by loss-cone accretion alone, and thus may require other additional accretion channels, such as gas accretion.

The ESA Euclid mission will survey more than 14,000 deg$^2$ of the sky in visible and near-infrared wavelengths, mapping the extra-galactic sky to constrain our cosmological model of the Universe. Although the survey focusses on regions further than 15 deg from the ecliptic, it should allow for the detection of more than about $10^5$ Solar System objects (SSOs). After simulating the expected signal from SSOs in Euclid images acquired with the visible camera (VIS), we describe an automated pipeline developed to detect moving objects with an apparent velocity in the range of 0.1-10 arcsec/h, typically corresponding to sources in the outer Solar System (from Centaurs to Kuiper-belt objects). In particular, the proposed detection scheme is based on Sourcextractor software and on applying a new algorithm capable of associating moving objects amongst different catalogues. After applying a suite of filters to improve the detection quality, we study the expected purity and completeness of the SSO detections. We also show how a Kohonen self-organising neural network can be successfully trained (in an unsupervised fashion) to classify stars, galaxies, and SSOs. By implementing an early-stopping method in the training scheme, we show that the network can be used in a predictive way, allowing one to assign the probability of each detected object being a member of each considered class.

The global rotational profile of the solar atmosphere and its variation at different layers, although crucial for a comprehensive understanding of the dynamics of the solar magnetic field, has been a subject to contradictory results throughout the past century. In this study, we thereby unify the results for different parts of the multi-thermal Solar atmosphere by utilizing 13 years of data in 7 wavelength channels of the Atmospheric Imaging Assembly (AIA) atop the Solar Dynamic Observatory (SDO). Using the method of image correlation, we find that the solar atmosphere exhibits a rotational profile that is up to 4.18% and 1.92% faster at the equator and comparatively less differential than that of the photosphere, as derived from Doppler measurements and sunspots, respectively and exhibits variation at different respective heights. Additionally, we find results suggestive of the role played by the rooting of different magnetic field structures on a comparison with helioseismology data.

The solar chromosphere exhibits a variety of waves originating from the photosphere and deeper layers, causing oscillations at different heights with distinct frequencies. This study identifies and analyze Atmospheric Gravity Waves (AGWs) and acoustic waves at various height pairs within the solar atmosphere utilising H$\alpha$, Ca II IR and Fe I 6173 A imaging spectroscopic observations from Swedish 1m Solar Telescope. We study and compare oscillations by analyzing power maps generated using velocities obtained from the filtergram difference and bisector methods. Our analysis shows a consistent increase in power with height in the solar chromosphere for both methods. In addition to this, our results show that AGWs are detected within or near magnetic flux concentration regions, where spicules are also predominant, exhibiting significant power in the chromosphere. These regions also feature inclined magnetic fields, which might be contributing to the propagation of these low-frequency AGWs in the chromosphere. Examining average power maps at spicule locations reveals significant power at AGWs frequency across different chromospheric heights. We speculate that these AGWs propagate upward along spicular structures and were not previously detected in the studies employing space-time map due to their limited lifetime. This study provides insights into the complex dynamics of solar chromospheric waves influenced by magnetic field, contributing to our understanding of AGWs and acoustic waves propagation across different layers of the solar atmosphere.

We introduce a novel galaxy classification methodology based on the visible spectra of a sample of over 68,000 nearby ($z\leq 0.1$) Sloan Digital Sky Survey lenticular (S0) galaxies. Unlike traditional diagnostic diagrams, which rely on a limited set of emission lines and class dividers to identify ionizing sources, our approach provides a comprehensive framework for characterizing galaxies regardless of their activity level. By projecting galaxies into the 2D latent space defined by the first three principal components (PCs) of their entire visible spectra, our method remains robust even when data from individual emission lines are missing. We employ Gaussian kernel density estimates of the classical Baldwin-Phillips-Terlevich (BPT) activity classes in the new classification subspace, adjusted according to their relative abundance in our S0 sample, to generate probability maps for star-forming, Seyfert, composite, and LINER galaxies. These maps closely mirror the canonical distribution of BPT classes shown by the entire galaxy population, demonstrating that our PC-based taxonomy effectively predicts the dominant ionizing mechanisms through a probabilistic approach that provides a realistic reflection of galaxy activity and allows for refined class membership. Our analysis further reveals that flux-limited BPT-like diagrams are inherently biased against composite and star-forming galaxies due to their weaker [OIII] emission. Besides, it suggests that although most low-activity galaxies excluded from these diagnostics exhibit visual spectra with LINER-like characteristics, their remaining activity is likely driven by mechanisms unrelated to either star formation or supermassive black hole accretion. A machine-readable catalogue listing BPT-class probabilities for the galaxies analysed is available online at the CDS website.

We present a novel visualization application designed to explore the time-dependent development of magnetic fields of neutron stars. The strongest magnetic fields in the universe can be found within neutron stars, potentially playing a role in initiating astrophysical jets and facilitating the outflow of neutron-rich matter, ultimately resulting in the production of heavy elements during binary neutron star mergers. Since such effects may be dependent on the strength and configuration of the magnetic field, the formation and parameters of such fields are part of current research in astrophysics. Magnetic fields are investigated using simulations in which various initial configurations are tested. However, the long-term configuration is an open question, and current simulations do not achieve a stable magnetic field. Neutron star simulations produce data quantities in the range of several terabytes, which are both spatially in 3D and temporally resolved. Our tool enables physicists to interactively explore the generated data. We first convert the data in a pre-processing step and then we combine sparse vector field visualization using streamlines with dense vector field visualization using line integral convolution. We provide several methods to interact with the data responsively. This allows the user to intuitively investigate data-specific issues. Furthermore, diverse visualization techniques facilitate individual exploration of the data and enable real-time processing of specific domain tasks, like the investigation of the time-dependent evolution of the magnetic field. In a qualitative study, domain experts tested the tool, and the usability was queried. Experts rated the tool very positively and recommended it for their daily work.

In a wide-area spectroscopic survey of galaxies, it is nearly impossible to obtain a homogeneous sample of galaxies with respect to galaxy properties such as stellar mass and host halo mass across a range of redshifts. Despite the selection effect, theoretical templates in most analyses assume single tracers when compared with the measured clustering quantities. We demonstrate analytically that the selection effect inevitably introduces a bias in the redshift-space power spectrum on scales from linear to nonlinear scales. To quantitatively assess the impact of the selection effect, we construct mock galaxy catalogs from halos in N-body simulations by selecting halos above redshift-dependent mass thresholds such that the resulting redshift distribution of the halos, $n(z)$, matches that of SDSS-like galaxies. We find that the selection effect causes fractional changes of up to only 1% and 2% in the monopole and quadrupole moments of the redshift-space power spectrum at $k\lesssim 0.3~h{\rm{Mpc}}^{-1}$, respectively, compared to the moments for the single mass-threshold (therefore single tracer) sample, for $n_{\rm g}(z)$ of the SDSS-like galaxy samples. We also argue that the selection effect is unlikely to cause a significant bias in the estimation of cosmological parameters using the Fisher matrix method, provided that the redshift-dependent selection effect is modest.

We present Sapphire++, an open-source code designed to numerically solve the Vlasov-Fokker-Planck equation for astrophysical applications. Sapphire++ employs a numerical algorithm based on a spherical harmonic expansion of the distribution function, expressing the Vlasov-Fokker-Planck equation as a system of partial differential equations governing the evolution of the expansion coefficients. The code utilises the discontinuous Galerkin method in conjunction with implicit and explicit time stepping methods to compute these coefficients, providing significant flexibility in its choice of spatial and temporal accuracy. We showcase the code's validity using examples. In particular, we simulate the acceleration of test particles at a parallel shock and compare the results to analytical predictions. The Sapphire++ code (this https URL) is available as a free and open-source tool for the community.

A growing number of directly-imaged companions have been recently characterised, with robust constraints on carbon-to-oxygen ratios and even isotopic ratios. Many companions and isolated targets have also shown spectral variability. In this work we observed the super-Jupiter AB~Pictoris~b across four consecutive nights using VLT/CRIRES+ as part of the ESO SupJup survey, exploring how the constraints on chemical composition and temperature profile change over time using spectral line shape variations between nights. We performed atmospheric retrievals of the high-resolution observations and found broadly consistent results across all four nights, but there were differences for some parameters. We clearly detect H$_2$O, $^{12}$CO and $^{13}$CO in each night, but abundances varied by $\sim2\sigma$, which was correlated to the deep atmosphere temperature profiles. We also found differences in the $^{12}$C$/^{13}$C ratios in each night by up to $\sim3\sigma$, which seemed to be correlated with the cloud deck pressure. Our combined retrieval simultaneously analysing all nights together constrained broadly the average of each night individually, with the C/O$=0.59\pm0.01$, consistent with solar composition, and $^{12}$C$/^{13}$C~$ = 102\pm8$, slightly higher than the ISM and Solar System values. We also find a low projected rotational velocity, suggesting that AB~Pictoris~b is either intrinsically a slow rotator due to its young age or that the spin axis is observed pole-on with a $\sim90^\circ$ misalignment with its orbit inclination. Future observations will be able to further explore the variability and orbit of AB~Pictoris~b as well as for other companions.

Aims: We aim to better characterize the conditions of the solar corona and especially with respect to the occurrence of confined and eruptive flares. Therefore, we have modeled the coronal evolution around 231 large flares observed during solar cycle 24. Methods: Using Helioseismic and Magnetic Imager vector magnetic field data around each event, we employ nonlinear force-free field extrapolations to approximate the coronal energy and helicity budgets of the solar source regions. Superposed epoch analysis and dynamical time warping applied to the time series of selected photospheric and coronal quantities is used to pin down the characteristics of the pre- and post-flare time evolution, as well as to assess flare-related changes. Results: (1) During the 24 hours leading to a major flare, the total magnetic energy and unsigned magnetic flux evolve closely with respect to each other, irrespective of the flare type. Prior to confined flares the free energy evolves more similar with respect to the unsigned flux than the helicity of the current-carrying field, while it is the opposite prior to eruptive flares. (2) The flare type can be predicted correctly in more than 90\% of major flares when combining measures of the active regions nonpotentiality and local stability. (3) The coronal energy and helicity budgets return to preflare levels within $\approx$\,6 to 12~hours after eruptive major M-class flares while the impact of eruptive X-flares lasts considerably longer. (4) Postflare replenishment times of $\gtrsim$12~hours after eruptive X-class flares may serve as a partial explanation for the rare observation of eruptive X-class flares within a few hours.

In recent years the chemistry of sulfur in the interstellar medium has experienced a renewed interest due to the detection of a large variety of molecules containing sulfur. Here we report the first identification in space of a new S-bearing molecule, thioacetaldehyde (CH3CHS), which is the sulfur counterpart of acetaldehyde (CH3CHO). The astronomical observations are part of QUIJOTE, a Yebes 40m Q band line survey of the cold dense cloud TMC-1. We detected seven individual lines corresponding to A and E components of the four most favorable rotational transitions of CH3CHS covered in the Q band (31.0-50.3 GHz). Assuming a rotational temperature of 9 K, we derive a column density of 9.8e10 cm-2 for CH3CHS, which implies that it is 36 times less abundant than its oxygen counterpart CH3CHO. By comparing the column densities of the O- and S-bearing molecules detected in TMC-1, we find that as molecules increase their degree of hydrogenation, sulfur-bearing molecules become less abundant compared to their oxygen analog. That is, hydrogenation seems to be less favored for S-bearing molecules than for O-bearing ones in cold sources like TMC-1. We explored potential formation pathways to CH3CHS and implemented them into a chemical model, which however underestimates by several orders of magnitude the observed abundance of thioacetaldehyde. Quantum chemical calculations carried out for one of the potential formation pathways, the S + C2H5 reaction, indicate that formation of CH3CHS is only a minor channel in this reaction.

Recently, an identified non-interacting black hole (BH) binary, Gaia ID 3425577610762832384 (hereafter G3425), contains a BH ($\sim$3.6 M$_{\odot}$) falling within the mass gap and has a nearly circular orbit, challenging the classical binary evolution and supernova theory. Here, we propose that G3425 originates from a triple through a triple common envelope (TCE) evolution. The G3425 progenitor originally may consist of three stars with masses of 1.49 M$_{\odot}$, 1.05 M$_{\odot}$, and 21.81 M$_{\odot}$, and inner and outer orbital periods of 4.22 days and 1961.78 days, respectively. As evolution proceeds, the tertiary fills its Roche lobe, leading to a TCE. We find that the orbital energy generated by the inspiral of the inner binary serves as an additional energy imparted for ejecting the common envelope (CE), accounting for $\sim$97\% of the binding energy in our calculations. This means that the outer orbit needs to expend only a small amount of the orbital energy to successfully eject CE. The outcome of the TCE is a binary consisting of a 2.54 M$_\odot$ merger produced by the inner binary merger and a 7.67 M$_\odot$ helium star whose CE successfully ejected, with an orbital period of 547.53 days. The resulting post-TCE binary (PTB) has an orbital period that is 1-2 orders of magnitude greater than the orbital period of a successfully ejected classical binary CE. In subsequent simulations, we find that the successfully ejected helium star has a 44.2\% probability of forming a BH. In the case of a non-complete fallback forming a BH, with an ejected mass of 2.6 M$_{\odot}$ and a relatively low natal kick ($11^{+16}_{-5}$ ${\rm km/s}$ to $49^{+39}_{-39}$ ${\rm km/s}$), this PTB can form G3425 in the Milky Way.

We present high-resolution e-MERLIN and EVN (e-VLBI) observations of a radio source associated with Dyson Sphere candidate G, identified as part of Project Hephaistos. The radio source, VLASS J233532.86-000424.9, is resolved into 3 compact components and shows the typical characteristics of a radio-loud AGN. In particular, the EVN observations show that it has a brightness temperature in excess of $10^{8}$~K. No radio emission is detected at the position of the M-dwarf star. This result confirms our earlier hypothesis, that at least some of the Dyson Sphere candidates of project Hephaistos are contaminated by obscured, background AGN, lying close to the line of sight of otherwise normal galactic stars. High-resolution radio observations of other Dyson Sphere candidates can be useful in distinguishing truly promising candidates from those contaminated by background sources.

We provide a technique for resolving intermediate-separation binaries stars with medium-sized telescopes (i.e. diameter less than or equal to 2.5 m) at wavelengths around 825 nm in the super-resolution range (i.e. below the limit defined by the Rayleigh criterion). We combined two well-known algorithms that have been applied to reduce the halo in lucky imaging observations: COvariancE of Lucky Images (COELI) and the Lucky Imaging Speckle Suppression Algorithm (LISSA). We reviewed the fundamentals of both algorithms and describe a new technique called Lucky Imaging Super resolution Technique (LIST), which is optimized for peak highlighting within the first ring of the Airy pattern. To validate the technique, we carried out several observing campaigns of well-known binary stars with FastCam on the 1.52 m TCS and 2.56 m NOT. The projected angular separation between objects was resolved by applying LIST with a result below 0.15". It can go down to approximately 0.05", given the limitations of the detector plate scale. This is, to our knowledge, the first time that binary companions with such small angular separations have been detected using only lucky imaging at optical wavelengths. The average accuracy achieved for the angular separation measurement is 16 mas with NOT and is 20 mas with TCS. The average accuracy obtained for the position angle measurement is $9.5^o$ for NOT and $11^o$ for TCS. We also made an attempt to measure the relative brightnesses of the binary components, obtaining results that are compatible with literature measurements. Lucky imaging, in combination with speckle suppression and a covariance analysis, can allow the resolution of multiple point sources below the diffraction limit of 2-m class telescopes. However, it should be noted that measurements in the super-resolution regime are less sensitive than those above the first Airy ring.

Most stars form in dense clusters within high-mass star-forming regions, where protoplanetary disks may be exposed to intense UV radiation from nearby massive stars. While previous studies have typically focused on isolated sources in low-mass regions, recent observational campaigns have started to probe the chemistry of irradiated disks in unprecedented detail. Interpreting this data requires complex chemical models, yet few studies have examined these disks' chemistry, and none have incorporated the photoevaporative wind launched by external UV fields into their physical structure. In this study, we post-process radiation hydrodynamics simulations of externally irradiated protoplanetary disks using the thermochemical code DALI, comparing models with and without the wind to assess its impact on disk chemistry. Results show that UV radiation is rapidly attenuated by the disk in both cases. However, thermal re-emission from the wind at longer wavelengths enhances disk heating, increasing the gas-phase abundances of some key volatiles. Synthetic line fluxes vary by orders of magnitude between wind and windless models, primarily due to emission from the wind itself rather than abundance variations within the disk. Our findings demonstrate that the photoevaporative wind significantly influences the physical and chemical structure, and observational characteristics, of externally irradiated disks. We conclude that incorporating the wind into chemical models is essential for accurately predicting chemical abundances, interpreting observations, and ultimately understanding planet formation in these common yet complex environments.

The young disc vertical phase is paramount in our understanding of Galaxy evolution. Analysing the vertical kinematics at different galactic regions provides important information about the space-time variations of the Galactic potential. The vertical phase snail-shell structure found after Gaia DR2 release encompasses a wide range of ages. %\citep{2018Natur.561..360A, Antoja23}. However, the structure of the $V_Z\, vs \, Z$ diagram appears linear when the analysis is limited to studying objects younger than 30 Ma. Based on the vertical velocity and height-over-disc maps obtained for a sample of young open clusters, this method also allows the matter density in the Solar neighbourhood to be estimated using a completely different approach than previously found in the literature. We use two different catalogues of star clusters to confirm the previous result and study new age ranges. The linear pattern between $V_Z$ and $Z$ shows different slopes, $\partial V_Z/\partial Z$, for various age groups. The results fit a simple model (harmonic oscillator) of in-plane decoupled vertical dynamics up to a certain age limit, corresponding to $\sim$ 30 Ma. This work also analyses the relationship between the local volumetric density of matter ($\rho_0$) and the disc vertical kinematics for different age ranges, all below 50 Ma. The best estimates of the effective volumetric mass density in the Solar neighbourhood, 0.09-0.15 M$_\odot$ pc${}^{-3}$, agree with those given by other authors, assessing the reliability of the proposed dynamical model. These values are a minorant of the actual matter density in the region.

We present our results on two Z Cam stars: Z Cam and AT Cnc. We apply observational data for the periods that cover the states of outbursts and standstills, which are typical for this type of objects. We report an appearance of periodic oscillations in brightness during the standstill in AT Cnc, with small amplitude variations of 0.03 - 0.04 mag and periodicity of $\approx 20-30$ min. Based on the estimated derredened color index (B - V )0, we calculate the color temperature for both states of the two objects. During the transition from the outbursts to the standstill's state Z Cam varies from bluer to redder, while AT Cnc stays redder in both states. We calculate some of the stars' parameters as: the radii of the primary and secondary components, and the orbital separation for both objects. We construct the profiles of the effective temperature in the discs of the two objects. Comparing the parameters of both systems, we see that Z Cam is definitely the hotter object and we conclude it has a more active accretion disk.

We show that the 32 $H(z)$ data from cosmic chronometers have overestimated uncertainties and make use of a Bayesian method to correct and reduce it. We then use the corrected data to constrain flat $\Lambda$CDM and O$\Lambda$CDM parameters. For the flat $\Lambda$CDM model, we got as result $H_{0} = 67.1\pm 4.0$ km s$^{-1}$ Mpc$^{-1}$ and $\Omega _{m} = 0.333 ^{+0.041}_{-0.057}$. While for the O$\Lambda$CDM model, we found $H_{0} = 67.2\pm 4.8$ km s$^{-1}$ Mpc$^{-1}$, $\Omega _{m} = 0.36\pm 0.16$ and $\Omega _{\Lambda} =0.71 ^{+0.36}_{-0.28}$. These results goes from $22\%$ up to $28\%$ uncertainty reduction when compared to the constraints of the both uncorrected models.

PSR J2030+4415 is a gamma-ray pulsar with an X-ray pulsar wind nebula elongated along the north-south direction. The system shows a prominent X-ray filament oriented at an angle of 130° to the nebula axis. To improve our understanding of the non-thermal processes occurring in the pulsar wind nebula, we attempted to determine the possible existence of a radio counterpart, study its morphology, and obtain restrictive upper limits of the pulsar and filament emission at radio wavelengths. We performed observations of the pulsar PSR J2030+4415 and its surroundings with the upgraded Giant Metrewave Radio Telescope (uGMRT) at two frequency bands, and put the results in context with findings at other wavelengths. We obtained radio images at 736 and 1274 MHz that reveal a structure trailing the pulsar, with a morphology overlapping the X-ray nebula. This radio structure is the radio counterpart of the X-ray pulsar wind nebula. The derived spectral index along this structure shows spatial variation. There are no hints of the pulsar and the filament at any of the explored radio frequencies, but we obtained restrictive upper limits. A physical scenario that combines the radio and the X-ray observations, and consistent with IR data, of the nebula and the filament is presented. We propose that particle acceleration occurs in the nebula tail due to the presence of a re-collimation shock, and the highest energy particles gradually escape from it through energy-dependent diffusion. We also find a lower limit in the energy of the particles escaping along the X-ray filament of ~GeV.

We present the confirmation of a compact galaxy group candidate, CGG-z4, at $z=4.3$ in the COSMOS field. This structure was identified by two spectroscopically confirmed $z=4.3$ $K_s$-dropout galaxies with ALMA $870\rm\, \mu m$ and 3 mm continuum detections, surrounded by an overdensity of NIR-detected galaxies with consistent photometric redshifts of $4.0<z<4.6$. The two ALMA sources, CGG-z4.a and CGG-z4.b, are detected with both CO(4-3) and CO(5-4) lines. [CI](1-0) is detected on CGG-z4.a, and H$_{2}$O($1_{1,0}-1_{0,1}$) absorption is detected on CGG-z4.b. We model an integrated spectral energy distribution by combining the FIR-to-radio photometry of this group and estimate a total star formation rate of $\rm\sim2000\, M_{\odot}$ yr$^{-1}$, making it one of the most star-forming groups known at $z>4$. Their high CO(5-4)/CO(4-3) ratios indicate that the inter-stellar mediums (ISMs) are close to thermalization, suggesting either high gas temperatures, densities, and/or pressure, while the low [CI](1-0)/CO(4-3) line ratios indicate high star formation efficiencies. With [CI]-derived gas masses we found the two galaxies have extremely short gas depletion times of $99$ Myr and $<63$ Myr respectively, suggesting the onset of quenching. With an estimated halo mass of $\rm log (M_{\rm halo}[M_{\odot}])\sim12.8$, we suggest that this structure is likely in the process of forming a massive galaxy cluster.

Rotation deeply impacts the structure and the evolution of stars. To build coherent 1D or multi-D stellar structure and evolution models, we must systematically evaluate the turbulent transport of momentum and matter induced by hydrodynamical instabilities of radial and latitudinal differential rotation in stably stratified thermally diffusive stellar radiation zones. In this work, we investigate vertical shear instabilities in these regions. The full Coriolis acceleration with the complete rotation vector at a general latitude is taken into account. We formulate the problem by considering a canonical shear flow with a hyperbolic-tangent profile. We perform linear stability analysis on this base flow using both numerical and asymptotic Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) methods. Two types of instabilities are identified and explored: inflectional instability, which occurs in the presence of an inflection point in shear flow, and inertial instability due to an imbalance between the centrifugal acceleration and pressure gradient. Both instabilities are promoted as thermal diffusion becomes stronger or stratification becomes weaker. Effects of the full Coriolis acceleration are found to be more complex according to parametric investigations in wide ranges of colatitudes and rotation-to-shear and rotation-to-stratification ratios. Also, new prescriptions for the vertical eddy viscosity are derived to model the turbulent transport triggered by each instability. We foresee that the inflectional instability will be responsible for turbulent transport in the equatorial region of strongly-stratified radiative zones in slowly rotating stars while the inertial instability triggers turbulence in the polar regions of weakly-stratified radiative zones in fast-rotating stars.

Studying exoplanet atmospheres is essential for assessing their potential to host liquid water and their capacity to support life (their habitability). Each atmosphere uniquely influences the likelihood of surface liquid water, defining the habitable zone (HZ), the region around a star where liquid water can exist. However, being within the HZ does not guarantee habitability, as life requires more than just liquid water. In this study, we adopted a two-pronged approach. First, we estimated the surface conditions of planets near the HZ's inner edge under various atmospheric compositions. By utilizing a 3D climate model, we refined the inner boundaries of the HZ for planets with atmospheres dominated by H2 and CO2 for the first time. Second, we investigated microbial survival in these environments, conducting laboratory experiments on the growth and survival of E. coli K-12, focusing on the impact of different gas compositions. This innovative combination of climate modeling and biological experiments bridges theoretical climate predictions with biological outcomes. Our findings indicate that atmospheric composition significantly affects bacterial growth patterns, highlighting the importance of considering diverse atmospheres in evaluating exoplanet habitability and advancing the search for life beyond Earth.

Strong lensing time delay measurement is a promising method to address the Hubble tension, offering a completely independent approach compared to both the cosmic microwave background analysis and the local distance ladder. As a third-party examination of the Hubble tension, this method provides a unique perspective. Strongly lensed quasar (glQSO) systems have demonstrated significant potential in tackling this issue, achieving an impressive \(2\%\) accuracy level. However, advancing to \(1\%\) or sub-percent accuracy is challenging due to several intrinsic limitations of glQSOs. Fortunately, strongly lensed supernovae (glSNe) offer a more robust solution, thanks to their characteristic light curve, significant brightness variations, and additional advantages. The Muztagh-Ata 1.93m Synergy Telescope (MOST) is an exceptional instrument for monitoring strong lensing time delays. In this study, we simulate the follow-up multi-band light curve monitoring for glSNe Ia systems, which are expected to be firstly discovered by the Chinese Survey Space Telescope (CSST). Our results show that with \(300s \times 9\) exposures in each epoch, MOST can achieve a signal-to-noise ratio (SNR) of approximately 50 for the brightest images of glSNe Ia, while even the faintest images maintain an SNR of at least 7. Using a standard SNe Ia light curve template for fitting, we measured the time delays. With a 2-day cadence, MOST achieves a time delay error of only a few hours, with the bias typically remaining below one hour. This study highlights the capability of MOST to significantly advance the precision of time delay measurements, offering a promising path toward resolving the Hubble tension.

The architecture and composition of planetary systems are thought to be strongly influenced by the transport and delivery of dust and volatiles via ices on pebbles during the planet formation phase in protoplanetary discs. Understanding these transport mechanisms is crucial in building a comprehensive picture of planet formation, including material and chemical budget; constraining the birth properties of these discs is a key step in this process. We present a novel method of retrieving such properties by studying the transport of icy pebbles in the context of an observed gas-phase CO enhancement within the CO snowline in the protoplanetary disc around HD 163296. We combine Markov Chain Monte Carlo (MCMC) sampling with a fast model of radial drift to determine the birth gas mass and characteristic radius of the disc, and compare our results against observations and models in the literature; we find the birth-condition disc gas mass to be $\log_{10}(M_{\rm{disc}}/M_{\odot})=-0.64^{+0.19}_{-0.24}$ and the characteristic radius to be $\log_{10}(r_{\rm{c}}/\rm{AU})=2.30^{+0.45}_{-0.46}$. We additionally determine that dust grains must be `fragile' ($v_{f}=100~\mathrm{cms}^{-1}$) to retain enough dust to match current dust mass observations, with our lowest fragmentation velocity model providing a current-age dust mass of $\rm{M_{dust}}=662^{+518}_{-278} \rm{M_{\oplus}}$ based on the retrieved birth conditions. Using our retrieved birth conditions, we extend our simulations to mass of material reaching the water snowline in the inner disc, where terrestrial and super-Earth planets may be forming, and speculate on the nature of these exoplanets.

We present a study of atmospheric disturbances at Jezero Crater, Mars, using ground-based measurements of surface pressure by the Perseverance rover in combination with orbital images from the Mars Express and Mars Reconnaissance Orbiter missions. The study starts at Ls $\sim$ 13.3° in MY36 (March 6th, 2021) and extends up to Ls $\sim$ 30.3° in MY37 (February 28th, 2023). We focus on the characterization of the major atmospheric phenomena at synoptic and planetary-scales. These are the thermal tides (measured up to the sixth component), long-period pressure oscillations (periods > 1 sol), the Aphelion Cloud Belt, and the occasional development of regional dust storms over Jezero. We present the seasonal evolution of the amplitudes and phases of the thermal tides and their relation with the atmospheric dust content (optical depth). Three regional dust storms and one polar storm extending over Jezero produced an increase in the diurnal and semidiurnal amplitudes but resulted in inverse responses in their phases. We show that the primary regular wave activity is due to baroclinic disturbances with periods of 2-4 sols and amplitudes $\sim$ 1-15 Pa increasing with dust content, in good agreement with theoretical predictions by model calculations. The spacecraft images show a number of arc-shaped, spiral and irregular cyclonic vortices, traced by dust and clouds at the edge of the North Polar Cap, that could be behind some of the pressure oscillations measured at Jezero.

On the main sequence, the asteroseismic small frequency separation $\delta\nu_{02}$ between radial and quadrupole p-modes is customarily interpreted to be a direct diagnostic of internal structure. Such an interpretation is based on a well-known integral estimator relating $\delta\nu_{02}$ to a radially-averaged sound-speed gradient. However, this estimator fails, catastrophically, when evaluated on structural models of red giants: their small separations must therefore be interpreted differently. We derive a single expression which both reduces to the classical estimator when applied to main-sequence stellar models, yet reproduces the qualitative features of the small separation for stellar models of very evolved red giants. This expression indicates that the small separations of red giants scale primarily with their global seismic properties as $\delta\nu_{02} \propto \Delta\nu^2/\nu_\mathrm{max}$, rather than being in any way sensitive to their internal structure. Departures from this asymptotic behaviour, during the transition from the main-sequence to red giant regimes, have been recently reported in open-cluster Christensen-Dalsgaard (C-D) diagrams from K2 mission data. Investigating them in detail, we demonstrate that they occur when the convective envelope boundary passes a specific acoustic distance -- roughly a third of a wavelength at $\nu_\mathrm{max}$ -- from the centre of the star, at which point radial modes become maximally sensitive to the position of the boundary. The shape of the corresponding features on $\epsilon_p$ and C-D (or $r_{02}$) diagrams may be useful in constraining the nature of convective boundary mixing, in the context of undershooting beneath a convective envelope.

We highlight the potential benefits of a synergistic use of SKAO and ESO facilities for galaxy evolution studies, focusing on the role that ESO spectroscopic surveys can play in supporting next-generation radio continuum and atomic hydrogen (HI) surveys. More specifically we illustrate the role that currently available or soon to be operational ESO multiplex spectrographs can play for three classes of projects: large/deep redshift survey campaigns, integral field unit/Atacama Large Millimeter/submillimeter Array (IFU/ALMA) surveys of selected regions of sky, and IFU/ALMA follow-ups of selected samples. We conclude with some general recommendations for an efficient joint exploitation of ESO-SKAO surveys.

We introduce a novel framework to implement stochastic inflation on stochastic trees, modelling the inflationary expansion as a branching process. Combined with the $\delta N$ formalism, this allows us to generate real-space maps of the curvature perturbation that fully capture quantum diffusion and its non-perturbative backreaction during inflation. Unlike lattice methods, trees do not proceed on a fixed background since new spacetime units emerge dynamically as trees unfold, naturally incorporating metric fluctuations. The recursive structure of stochastic trees also offers remarkable numerical efficiency, and we develop the FOrtran Recursive Exploration of Stochastic Trees ($\texttt{FOREST}$) tool and demonstrate its performance. We show how primordial black holes blossom at unbalanced nodes of the trees, and how their mass distribution can be obtained while automatically accounting for the "cloud-in-cloud" effect. In the "quantum-well" toy model, we find broad mass distributions, with mild power laws terminated by exponential tails. We finally compare our results with existing approximations in the literature and discuss several prospects.

To power gamma-ray bursts and other high-energy events, large-scale magnetic fields are required to extract rotational energy from compact objects such as black holes and neutron stars. The magnetorotational instability (MRI) is a key mechanism for angular momentum transport and large-scale magnetic field amplification. Recent work has begun to address the regime of high magnetic Prandtl number $\mathrm{Pm}$, the ratio of viscosity to resistivity, in which angular momentum and magnetic energy increase with $\mathrm{Pm}$. This regime reveals unique dynamics of small-scale turbulence in disk mid-planes and buoyancy instabilities in the atmosphere. This study aims to build on these findings, focusing on the MRI-driven $\alpha\Omega$ dynamo in stratified simulations to understand magnetic field generation in the high-$\mathrm{Pm}$ regime. We analyze data taken from stratified shearing box simulations both in the regime of magnetic Prandtl number of order unity, and also in the high $\mathrm{Pm}$ regime employing new techniques to compute the dynamo coefficients. We find that the mean-magnetic field evolution can be described by an $\alpha\Omega$ dynamo, even in the high-Pm regime. The mean magnetic field as well as the dynamo coefficients increase with Pm. This leads to a shorter dynamo period and a faster growth rate. We also find that the off-diagonal coefficients have an impact on the propagation of the magnetic field in the dynamo region. Overall, the magnetic field amplification found in global simulations should be increased by at least a factor of $\sim 5$, which could lead to more powerful jets and stronger winds from astrophysical disks in the high-Pm regime.

The bispectrum of galaxy number counts is a key probe of large-scale structure (LSS), offering insights into the initial conditions of the Universe, the nature of gravity, and cosmological parameters. In this work, we derive the theoretical angular bispectrum of number counts for the first time without relying on the Limber approximation, while incorporating redshift binning. Notably, our analysis includes all Newtonian effects, leading relativistic projection effects, and general relativistic contributions, including radiation dynamics, up to second order in perturbation theory. For simplicity, however, we neglect any biasing effects. We have implemented these expressions in an open access code to evaluate the bispectrum for two redshift bins, $z=2 \pm 0.25$ and $z=0.6 \pm 0.05$, and compare our analytical results with simulations. For the contributions that already appear in a Newtonian treatment we find an interesting cancellation between the quadratic terms. At $z=2$, the projection effects and the dynamical effects have similar amplitude on large scales as we approach $k \sim \mathcal{H}$. In the squeezed limit, radiation effects are found to be the leading relativistic effects, by one order of magnitude. At $z=0.6$, we find the correct weak-field hierarchy between the terms, controlled by the ratio $\mathcal{H}/k$, but we still find that dynamical effects (from nonlinear evolution) are only a factor $2-3$ smaller than the projection effects. We compare our results with simulation measurements and find good agreement for the total bispectrum.

We introduce a novel approach to modelling the nebular emission from star-forming galaxies by combining the contributions from many HII regions incorporating loose trends in physical properties, random dust attenuation, a predefined Halpha luminosity function and a diffuse ionized-gas component. Using a machine-learning-based regression artificial neural network trained on a grid of models generated by the photoionization code Cloudy, we efficiently predict emission-line properties of individual HII regions over a wide range of physical conditions. We generate 250,000 synthetic star-forming galaxies composed of up to 3000 HII regions and explore how variations in parameters affect their integrated emission-line properties. Our results highlight systematic biases in oxygen-abundance estimates derived using traditional methods, emphasizing the importance of accounting for the composite nature of star-forming galaxies when interpreting integrated nebular emission. Future work will leverage this approach to explore in detail its impact on parameter estimates of star-forming galaxies.

Relative motions have long been known to mislead the unsuspecting observers to false interpretations of reality. The deceptions are usually brief and unimportant, though relative motions have also led to illusions that were both long-lasting and important. Indeed, in the history of astronomy there are several examples where relative-motion effects have misled us to gross misinterpretations. Here, we consider the possibility that our peculiar motion relative to the cosmic rest-frame can trigger deceptions on cosmological scales. In so doing, we will demonstrate that unsuspecting observers inside bulk peculiar flows may come to the false conclusion of recent accelerated expansion, when their host universe is actually decelerating. The same observers may then erroneously attribute their apparent acceleration to an also recent dramatic change in the nature of the cosmic medium. In reality, however, nothing has really happened. Despite the appearances, the host universe keeps decelerating and its material content retains its conventional form. Nevertheless, there are ways out of these illusions. Our observers can find out that they have been deceived by their own peculiar flow, by looking for the trademark signature of relative motion in their data. This signature is nothing else but a Doppler-like anisotropy in the sky distribution of the measured deceleration parameter. To the bulk-flow observers, the universe should appear to accelerate faster along a certain point on the celestial sphere and equally slower along the antipodal. Moreover, the magnitude of the apparent dipole should decrease with increasing redshift.

The dynamics of cosmic reheating, that is, on how the energy stored in the inflaton is transferred to the standard model (SM) thermal bath, is largely unknown. In this work, we show that the phenomenology of the nonbaryonic dark matter (DM) ultraviolet freeze-in production strongly depends on the dynamics of the cosmic-reheating era. Using a general parametrization for the Hubble expansion rate and SM temperature, we thoroughly investigate DM production during reheating, not only recovering earlier findings that focused on specific cases, but also exploring alternative scenarios. Additionally, we derive a generalized framework for DM production via inflaton decays and identify the viable parameter space, while simultaneously addressing constraints from CMB observations. As illustrative examples, we explore gravitational DM production through scatterings of SM particles or inflatons, deriving well-defined parameter regions for these scenarios.

Astronomy datasets can be challenging to use for high school astronomy classes. Data science education pedagogy can be leveraged to create astronomy activities in which students interrogate data, create visuals, and use statistical thinking to construct astronomy knowledge. This session describes how the NASA/IPAC Infrared Science Archive (IRSA) can provide a web-based interface for students to use basic data science techniques in astronomy to build data literacy while learning astronomical concepts. The activities shared will be available for anyone but were designed to be used in astro 101 classes in high school or early college.

Technical and environmental noise in ground-based laser interferometers designed for gravitational-wave observations like Advanced LIGO, Advanced Virgo and KAGRA, can manifest as narrow (<1Hz) or broadband ($10'$s or even $100'$s of Hz) spectral lines and features in the instruments' strain amplitude spectral density. When the sources of this noise cannot be identified or removed, in cases where there are witness sensors sensitive to this noise source, denoising of the gravitational-wave strain channel can be performed in software, enabling recovery of instrument sensitivity over affected frequency bands. This noise hunting and removal process can be particularly challenging due to the wealth of auxiliary channels monitoring the interferometry and the environment and the non-linear couplings that may be present. In this work, we present a comprehensive analysis approach and corresponding cyberinfrastructure to promptly identify and remove noise in software using machine learning techniques. The approach builds on earlier work (referred to as DeepClean) in using machine learning methods for linear and non-linear regression of noise. We demonstrate how this procedure can be operated and optimized in a tandem fashion close to online data taking; it starts off with a coherence monitoring analysis that first singles out and prioritizes witness channels that can then be used by DeepClean. The resulting denoised strain by DeepClean reflects a 1.4\% improvement in the binary neutron star range, which can translate into a 4.3\% increase in the sensitive volume. This cyber infrastructure we refer to as Coherence DeepClean, or CDC, is a significant step toward autonomous operations of noise subtraction for ground-based interferometers.

In the era of the next-generation gravitational-wave detectors, signal overlaps will become prevalent due to high detection rate and long signal duration, posing significant challenges to data analysis. While effective algorithms are being developed, there still lacks an integrated understanding on the statistical properties for the population of overlapping events. For the first time we rigorously derive and establish analytical expressions for the expectation and variance for the number of overlapping events to aid rapid and robust estimation. We also mathematically prove that the time difference between events in a single observation run is described by the beta distribution, offering an analytical prior reference for Bayesian analysis.