Papers for Monday, Feb 24 2025

This research studies the impact of high-quality training datasets on the performance of Convolutional Neural Networks (CNNs) in detecting strong gravitational lenses. We stress the importance of data diversity and representativeness, demonstrating how variations in sample populations influence CNN performance. In addition to the quality of training data, our results highlight the effectiveness of various techniques, such as data augmentation and ensemble learning, in reducing false positives while maintaining model completeness at an acceptable level. This enhances the robustness of gravitational lens detection models and advancing capabilities in this field. Our experiments, employing variations of DenseNet and EfficientNet, achieved a best false positive rate (FP rate) of $10^{-4}$, while successfully identifying over 88 per cent of genuine gravitational lenses in the test dataset. This represents an 11-fold reduction in the FP rate compared to the original training dataset. Notably, this substantial enhancement in the FP rate is accompanied by only a 2.3 per cent decrease in the number of true positive samples. Validated on the KiDS dataset, our findings offer insights applicable to ongoing missions, like Euclid.

Toroidal magnetic field is a key ingredient of relativistic jets launched by certain accreting astrophysical black holes, and of plasmoids emerging from the tearing instability during magnetic reconnection, a candidate dissipation mechanism in jets. Tension of toroidal field is an anisotropic force that can compress local energy and momentum densities. We investigate this effect in plasmoids produced during relativistic reconnection initiated from a Harris layer by means of kinetic particle-in-cell (PIC) numerical simulations, varying the system size (including 3D cases), magnetisation, or guide field. We find that: (1) plasmoid cores are dominated by plasma energy density for guide fields up to B_z ~ B_0; (2) relaxed 'monster' plasmoids compress plasma energy density only modestly (by factor ~3 above the initial level for drifting particle population); (3) energy density compressions by factors >~10 are achieved during plasmoid mergers, especially with the emergence of secondary plasmoids. This kinetic-scale effect can be combined with a global focusing of the jet Poynting flux along the quasi-cylindrical bunched spine (a proposed jet layer adjacent to the cylindrical core) due to poloidal line bunching (a prolonged effect of tension of the jet toroidal field) to enhance the luminosity of rapid radiation flares from blazars. The case of M87 as a misaligned blazar is discussed.

We perform fully relativistic simulations of the head-on collisions between intermediate-mass black holes and very massive stars. Such collisions are expected to occur in dense stellar clusters and may play an important role in growing the mass of the seed black hole. For the cases considered here, for which the masses of the black holes and stars are comparable, the vast majority of the stellar material is accreted onto the black hole within a stellar dynamical timescale, as expected from analytical estimates, and leads to a rapid growth of the black hole. A small amount of mass, which is shock-heated in the wake of the black hole, is ejected from the collision and will contribute to the interstellar material in the cluster.

We reconstruct the SFHs of 7 massive ($M_{\star}\gtrsim 10^{10} M_{\odot}$) early-type galaxies (ETGs) in the Virgo cluster by analysing their spatially resolved stellar population (SP), including their UV and H$\alpha$ emission. As part of the VESTIGE survey, we used H$\alpha$ images to select ETGs that show no signs of ongoing star formation. We combined VESTIGE with images from Astrosat/UVIT, GALEX and CFHT from the NGVS to analyse radial spectral energy distributions (SEDs) from the FUV to the NIR. The UV emission in these galaxies is likely due to old, low mass stars in post main sequence (PMS) phases, the UV upturn. We fit the radial SEDs with novel SP models that include an old, hot stellar component of PMS stars with various temperatures and energetics. This way, we explore the main stellar parameters responsible for UV upturn stars irregardless of their evolutionary path. Standard models are not able to reproduce the galaxies' central FUV emission (SMA/$R_{eff}\lesssim1$), while the new models well characterise it through PMS stars with temperatures T$\gtrsim$25000 K. All galaxies are old (mass-weighted ages $\gtrsim10$ Gyr) and the most massive M49 and M87 are supersolar within SMA/$R_{\rm eff}\lesssim0.2$. Overall, we found flat age gradients ($\nabla$Log(Age)$\sim -0.04 - 0$ dex) and shallow metallicity gradients ($\nabla$Log(Z)$<-0.2$ dex), except for M87 ($\nabla$Log($Z_{\rm M87}$)$\simeq-0.45$ dex). Our results show that these ETGs formed with timescales $\tau\lesssim1500$ Myr, having assembled between $\sim40-90\%$ of their stellar mass at $z\sim5$. This is consistent with recent JWST observations of quiescent massive galaxies at high$-z$, which are likely the ancestors of the largest ETGs in the nearby Universe. The derived flat/shallow gradients indicate that major mergers might have contributed to the formation and evolution of these galaxies.

Very massive stars with masses over 100 Msun are key objects in the Universe for our understanding of chemical and energetic feedback in the Universe, but their evolution and fate are almost entirely determined by their wind mass loss. We aim to determine the mass of the most massive star known in the Local Group R136a1. For this we compute the first hydrodynamically consistent non-local thermodynamical equilibrium atmosphere models for both R136a1 (WN5h) as well as the binary system R144 (WN5/6h+WN6/7h) in the Tarantula nebula. Using the Potsdam Wolf-Rayet code, we simultaneously empirically derive and theoretically predict mass-loss rates and wind velocities. By fitting synthetic spectra derived from these models to multi-wavelength observations, we constrain the stellar and wind properties of R144 and R136a1. We first determine the clumping stratification required by our hydro-models to fit the spectra of R144 by using the available dynamical mass estimates for the two components. We then utilise this clumping stratification in hydrodynamic models of R136a1 and estimate a mass of $M_\mathrm{Hydro}$ of 233 Msun. Remarkably, the estimated mass is close to and entirely consistent with chemical homogeneous mass relations. This present-day mass of 233 Msun provides a lower limit to the initial stellar mass, that could be far higher due to previous wind mass loss.

We investigate close encounters between initially unbound black holes (BHs) in the gaseous discs of active galactic nuclei (AGN), performing the first 3D non-isothermal hydrodynamical simulations of gas-assisted binary BH formation. We discuss a suite of 135 simulations, considering 9 AGN disc environments and 15 BH impact parameters. We find that the gas distribution within the Hill sphere about an isolated embedded BH is akin to a spherically symmetric star with a low-mass convective envelope and a BH core, with large convective currents driving strong outflows away from the midplane. We find that Coriolis force acting on the outflow results in winds, analogous to cyclones, that counter-rotate with respect to the midplane flow within the Hill sphere. We confirm the existence of strong thermal blasts due to minidisc collisions during BH close encounters, as predicted in our previous 2D studies. We document binary formation across a wide range of environments, finding formation likelihood is increased when the gas mass in the Hill sphere is large, allowing for easier binary formation in the outer AGN disc. We provide a comprehensive overview of the SMBH's role in binary formation, investigating how binary formation in intermediate density environments is biased towards certain binary orientations. We offer two models for predicting dissipation by gas during close encounters, as a function of the ambient Hill mass alone, or with the periapsis depth. We use these models to motivate a prescription for binary formation likelihood that can be readily applied to Monte-Carlo simulations of AGN evolution.

We present an analysis of the magnetic field strength and morphology in the Sagittarius C complex (Sgr C; G359.43-0.09) in the Milky Way Galaxy's Central Molecular Zone (CMZ) using the 214 $\mu$m polarimetry data acquired with the High-Angular-Resolution Wideband Camera+ (HAWC+) instrument aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). We use several hundred magnetic field pseudovectors in the Sgr C region to trace the projected magnetic field orientation within cold molecular gas clouds, and as is the trend throughout the CMZ, they show a higher polarization fraction toward the periphery of the clouds. We conduct a modified Davis-Chandrasekhar-Fermi (DCF) analysis of individual clouds and find that the sky-plane magnetic field strength varies from highly turbulent regions having inferred strengths of $\sim30~\mu{\rm G}$ to regions of relatively uniform field orientation having strengths of $\sim 1~{\rm mG}$. The magnetic field orientations suggest that outflows from active star-forming regions, such as the extended green object (EGO) G359.43-0.10 and the protostellar source FIR-4 (G359.43+0.02), cause high turbulence in their vicinity. The magnetic field direction is found to be tangential to the surface of the Sgr C HII region, as well as two [CII] emission cavities around this region. Several other features in the vicinity of Sgr C, especially numerous non-thermal filaments (NTFs) and a diffuse source of X-ray emission towards the southwest of the \hii{} region, are discussed with regard to the observed magnetic field pseudovectors.

Numerical simulations are essential to understand the complex physics accompanying the merger of binary systems of neutron stars. However, these simulations become computationally challenging when they have to model the merger remnants on timescales over which secular phenomena, such as the launching of magnetically driven outflows, develop. To tackle these challenges, we have recently developed a hybrid approach that combines, via a hand-off transition, a fully general-relativistic code (FIL) with a more efficient code making use of the conformally flat approximation (BHAC+). We here report important additional developments of BHAC+ consisting of the inclusion of gravitational-wave radiation-reaction contributions and of higher-order formulations of the equations of general-relativistic magnetohydrodynamics. Both improvements have allowed us to explore BNS merger remnants with high accuracy and over timescales that would have been computationally prohibitive otherwise. More specifically, we have investigated the impact of the magnetic-field strength on the long-term (\ie $\sim 200\,{\rm ms}$) and high-resolution (\ie $150\,{\rm m}$) evolutions of the ``magnetar'' resulting from the merger of two neutron stars with a realistic equation of state. In this way, and for sufficiently large magnetic fields, we observe the weakening or suppression of differential rotation and the generation of magnetic flares in the outer layers of the remnant. These flares, driven mostly by the Parker instability, are responsible for intense and collimated Poynting flux outbursts and mass ejections. This novel phenomenology offers the possibility of seeking corresponding signatures from the observations of short gamma-ray bursts and hence revealing the existence of a long-lived strongly magnetized remnant.

We present a model for analytically calculating gravitational lensing by self-interacting dark matter (SIDM) halos. Leveraging the universal behavior of SIDM halos during gravothermal evolution, we calibrate the lensing potential using a fluid simulation, normalizing the evolution time to align with established scenarios. From this potential, we derive explicit equations for the deflection angle and surface density profile, quantifying their deviations from numerical results. Our model builds on the parametric approach of arXiv:2305.16176, providing refinements in the deep core-collapse regime and enabling more comprehensive lensing studies. We explore characteristic lensing features, including critical curves and caustics, for SIDM halos in isolation and within a main halo, tracking their evolution through the gravothermal phase. We also examine signatures in the self-similar regime of core collapsed halos and highlight the role of baryonic effects in realistic halos. The efficiency of our model enables large-scale lensing studies, and we make our implementation publicly available on GitHub to support further research.

We explore the differences in gas-rich field Ultra-Diffuse Galaxies (UDGs) and classical dwarf galaxies using an extensive atomic gas (HI) follow-up survey of optically-selected UDG candidates from the Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes) catalogue. We also compare the SMUDGes-HI observations with two state-of-the-art cosmological hydrodynamical simulations: Numerical Investigation of a Hundred Astrophysical Objects (NIHAO), where UDGs form through a series of bursty star formation episodes and Romulus25, in which UDGs occupy dark matter halos with high spins as a result of major mergers. Although the suggested formation scenarios for UDGs within these simulations are different, the present-day HI masses $M_{HI}$, stellar masses $M_*$, and star formation rates $SFR$ of simulated galaxies are qualitatively and quantitatively consistent with each other and with the observed SMUDGes-HI sample. We find that when controlling for $M_*$, there is a positive correlation between the gas richness $M_{HI}$/$M_*$ and the effective optical radius $R_{eff}$ , and that this trend is not different between the UDG and dwarf populations, within the measured scatter. Taken together, our results suggest that gas-rich, star-forming UDGs and dwarfs are not distinct galaxy populations, either observationally or in simulations.

We present GalactiKit, a data-driven methodology for estimating the lookback infall time, stellar mass, halo mass and mass ratio of the disrupted progenitors of Milky Way-like galaxies at the time of infall. GalactiKit uses simulation-based inference to extract the information on galaxy formation processes encoded in the Auriga cosmological MHD simulations of Milky Way-mass halos to create a model that relates the properties of mergers to those of the corresponding merger debris at $z=0$. We investigate how well GalactiKit can reconstruct the merger properties given the dynamical, chemical, and the combined chemo-dynamical information of debris. For this purpose, three models were implemented considering the following properties of merger debris: (a) total energy and angular momentum, (b) iron-to-hydrogen and alpha-to-iron abundance ratios, and (c) a combination of all of these. We find that the kinematics of the debris can be used to trace the lookback time at which the progenitor was first accreted into the main halo. However, chemical information is necessary for inferring the stellar and halo masses of the progenitors. In both models (b) and (c), the stellar masses are predicted more accurately than the halo masses, which could be related to the scatter in the stellar mass-halo mass relation. Model (c) provides the most accurate predictions for the merger parameters, which suggests that combining chemical and dynamical data of debris can significantly improve the reconstruction of the Milky Way's assembly history.

The Whirlpool Galaxy is a well studied grand design galaxy with two major spiral arms, and a large satellite NGC 5195. The arms both show long uniform sections with perturbations ('kinks' or sharp turns) in specific regions. Comparing the two arms shows a small radial offset between the main kinked regions. We analysed the morphology and also the velocity field in the disk of M51 using kinematic maps based on H$\alpha$ and CO line emission. These sample complementary radial ranges, with the CO map covering the central zone and the H$\alpha$ map extending to cover the outer zone. We looked for indicators of density wave resonance, zones where radial flows of gas in the disk plane reverse their sign. These were present in both velocity maps; their two-dimensional localization placed them along or closely parallel to the spiral arms, at a set of well defined galactocentric radii, and notably more concentrated along the southern, stronger arm. The results can be well interpreted quantitatively, using a numerical model of the interaction of M51 and NGC5195 in which the satellite has made two relatively recent passes through the disk plane of M51. During the first pass the pair of dominant spiral arms was stimulated, and during the second pass the strong kinks in both arms were formed at about the same time. The second interaction is particularly well characterised, because the timescale corresponding to the production of the kinks and the recovery of the original pitch angle is identical for the two arms.

Accurate modeling of active galactic nucleus (AGN) feedback, especially due to relativistic jets, is crucial for understanding the cool-core problem in galaxy clusters. We present a new subgrid method to model accretion onto and feedback from AGN in hydrodynamical simulations of galaxy clusters. Instead of applying the traditional Bondi formalism, we use a sink particle algorithm in which the accretion flux is measured directly through a control surface. A weighting kernel is used to reset the gas properties within the accretion radius at the end of each timestep. We implement feedback in the form of bipolar jets whose properties are tied to the accretion rate. The method is tested with a spherically symmetric Bondi gas flow problem and a Bondi-Hoyle-Lyttleton wind problem, with and without jet feedback. We discuss the reliability of this model by comparing our jet simulations with those in the literature, and we examine the dependence of test results on parameters such as the resolution and size of the jet injection region. We find that the sink particle model can account for the $\alpha$ factor in accretion measurement, and the accretion radius must be resolved with at least two zones to produce realistic black hole accretion. We also show how under-resolving the AGN feedback region in simulations can impact the feedback energy deposited and the jet dynamics. The code described here is the framework for a feedback model, described in a companion paper, that will use accretion disk modeling to more self-consistently determine the feedback efficiency.

Coronal lines (CLs), which arise from collisionally excited forbidden transitions from highly ionized species, are a powerful diagnostic tool in uncovering active galactic nuclei (AGNs) and constraining their properties. However, recent optical surveys are finding that coronal lines are rarely detected in the majority of local AGNs, possibly as a result of the depletion of elements from the interstellar gas onto dust grains. Prominent CL emission may therefore only arise when dust is being destroyed in the highly ionized gas in AGNs. To explore the possibility that dust destruction may be caused by ionized gas outflows in galaxies with prominent CLs, we present the first large-scale systematic study of ionized outflows, as traced by the [O III] $\lambda$5007 emission, in galaxies displaying CL emission relative to a robust control sample of non-CL-emitting galaxies. We find: 1) galaxies that display CL emission have a significantly elevated outflow incidence rate compared to their matched controls, 2) the outflow luminosity is significantly higher in the CL-emitters, 3) the CL-emitters have systematically lower intrinsic extinction toward the ionized gas compared with the controls, 4) there are significant correlations between the CL luminosity and outflow velocity for the iron CLs, with similar relationships found between the CL FWHM and outflow luminosity. These observations are consistent with dust destruction in an outflowing wind from a dusty torus causing efficient CL emission.

In 1777 Ruđer Bošković observed sunspots, determined their positions and the solar rotation elements by his own methods briefly described here. We repeat his calculations of the mean solar time, sunspot positions, and solar rotation elements using both the Bošković's original equations and equations adapted for modern computers. We repeat the calculations using two values of the obliquity of the ecliptic, Bošković's, and an interpolated one. Using his 1777 observations, Bošković obtained the solar equator's inclination, ecliptic longitude of the ascending node, and sidereal and synodic rotation periods. We analyzed and compared these original Bošković results with our repeated calculations. Our results confirm the validity of Bošković's methods and the precision of his calculations. Additionally, the paper presents the solar differential rotation determination using all 1777 observations by Ruđer Bošković.

Dense gas in molecular clouds is an important signature of ongoing and future star formation. We identify and track dense cores in the STARFORGE simulations, following the core evolution from birth through dispersal by stellar feedback for typical Milky Way cloud conditions. Only $\sim$8% of cores host protostars, and most disperse before forming stars. The median starless and protostellar core lifetimes are $\sim 0.5-0.6$ Myr and $\sim0.8-1.1$ Myr, respectively, where the protostellar phase lasts $\sim 0.1^{+0.1}_{-0.05}$ Myr. While core evolution is stochastic, we find that virial ratios and linewidths decline in prestellar cores, coincident with turbulent decay. Collapse occurs over $\sim 0.1$ Myr, once the central density exceeds $\gtrsim 10^6$cm$^{-3}$. Starless cores, only, follow linewidth-size and mass-size relations, $\sigma \propto R^{0.3}$ and $M \propto R^1$. The core median mass, radius, and velocity dispersion scale weakly with the cloud magnetic field strength. We cluster the core properties and find that protostellar cores have $>80$% likelihood of belonging to three particular groups that are characterized by high central densities, compact radii, and lower virial parameters. Overall, core evolution appears to be universally set by the interplay of gravity and magnetized turbulence, while stellar feedback dictates protostellar core properties and sets the protostellar phase lifetime.

Solar flares are defined as outbursts on the surface of the Sun. They occur when energy accumulated in magnetic fields enclosing solar active regions (ARs) is abruptly expelled. Solar flares and associated coronal mass ejections are sources of space weather that adversely impact devices at or near Earth, including the obstruction of high-frequency radio waves utilized for communication and the deterioration of power grid operations. Tracking and delivering early and precise predictions of solar flares is essential for readiness and catastrophe risk mitigation. This paper employs the random forest (RF) model to address the binary classification task, analyzing the links between solar flares and their originating ARs with observational data gathered from 2011 to 2021 by this http URL and the XRT flare database. We seek to identify the physical features of a source AR that significantly influence its potential to trigger >=C-class flares. We found that the features of AR_Type_Today, Hale_Class_Yesterday are the most and the least prepotent features, respectively. NoS_Difference has a remarkable effect in decision-making in both global and local interpretations.

Solar energetic particles such as electrons can be accelerated to mildly-relativistic velocities in the solar corona. These electrons travel through the turbulent corona generating radio waves, which are then severely affected by scattering. The physical interpretation of the discrepancies between the actual and observed radio sources is still subject to debate. Here, we use radio emission observed by an unprecedented total of five spacecraft, to track the path of radio sources from the low corona to the inner heliosphere (15-75 R$_{\odot}$) generated during a solar event on 4 December 2021. In this study we use the Bayesian multilateration technique known as BELLA to track the apparent path of radio sources observed by Parker Solar Probe, STEREO A, Wind, Solar Orbiter and Mars Express. To validate the accuracy of the tracked path, we used Nançay Radioheliograph interferometric imaging at 150 MHz, which was found to agree with the estimated footpoints predicted by BELLA. We also further validated our results using ACE in-situ measurements. We found that the apparent radio sources followed the path of a Parker Spiral, with an associated solar wind velocity of approximately 493 km s-1 (consistent with the corresponding speed observed at 1 au at the relevant longitude) and connected to 75$^\circ$ longitude East at the solar surface. Finally, we made quantitative estimates of the scattering of radio waves that were found to be in good agreement with contemporary models of scattering. This work shows conclusive evidence that the disputed cause of the widely observed `higher than expected' electron densities at interplanetary distances is due to radio wave scattering, and provides a more detailed understanding of the propagation of radio waves emitted near the local plasma frequency in turbulent plasmas.

Low Earth orbit (LEO) satellite constellations bring broadband internet and cellular service to the most remote locations on the planet. Unfortunately, many of these locations also host some of the world's best optical and radio astronomy (RA) observatories. With the number of LEO satellites expected to increase by an order of magnitude in the upcoming decade, satellite downlink radio frequency interference (RFI) is a growing concern in protected radio-quiet areas like the United States National Radio Quiet Zone. When these satellites transmit in the spectrum near protected RA bands, undesired out-of-band emission can leak into these protected bands and impact scientific observations. In this paper, we present a self-reporting system - Operational Data Sharing (ODS) - which enables mutual awareness by publishing radio telescopes' operational information to a protected database that is available to satellite operators through a representational state transfer application programming interface (REST API). Satellite operators can use the ODS data to adapt their downlink tasking algorithms in real time to avoid overwhelming sensitive RA facilities, particularly, through the novel Telescope Boresight Avoidance (TBA) technique. Preliminary results from recent experiments between the NRAO and the SpaceX Starlink teams demonstrate the effectiveness of the ODS and TBA in reducing downlink RFI in the Karl G. Jansky Very Large Array's observations in the 1990-1995 MHz and 10.7-12.7 GHz bands. This automated ODS system is beginning to be implemented by other RA facilities and could be utilized by other satellite operators in the near future.

The star-forming region Cepheus A hosts a very young star, called HW2, that is the second closest to us growing a dozen times more massive than our Sun. The circumstellar environment surrounding HW2 has long been the subject of much debate about the presence or not of an accretion disk, whose existence is at the basis of our current paradigm of star formation. Here, we answer this long standing question by resolving the gaseous disk component, and its kinematics, through sensitive observations at cm wavelengths of hot ammonia (NH$_3$) with the Jansky Very Large Array. We map the accretion disk surrounding HW2 at radii between 200 and 700 au, showing how fast circumstellar gas collapses and slowly orbits to pile up near the young star at very high rates of $2\times10^{-3}$ M$_{\odot}$ yr$^{-1}$. These results, corroborated by state-of-the-art simulations, show that an accretion disk is still efficient in focusing huge mass infall rates near the young star, even when this star has already reached a large mass of 16 M$_{\odot}$.

MAROON-X is a state-of-the-art extreme precision radial velocity spectrograph deployed on the 8.1-meter Gemini-N telescope on Maunakea, Hawai'i. Using a stabilized Fabry-Pérot etalon for wavelength and drift calibration, MAROON-X has achieved a short-term precision of $\sim$\,30\,cm\,s$^{-1}$. However, due to a long-term drift in the etalon (2.2\,cm\,s$^{-1}$ per day) and various interruptions of the instrument baseline over the first few years of operation, MAROON-X experiences RV offsets between observing runs several times larger than the short-term precision during any individual run, which hinders the detection of longer-period signals. In this study, we analyze RV measurements of 11 targets that either exhibit small RV scatter or have signals that can be precisely constrained using Keplerian or Gaussian Process models. Leveraging this ensemble, we calibrate MAROON-X's run offsets for data collected between September 2020 and early January 2024 to a precision of $\sim$0.5\,m\,s$^{-1}$. When applying these calibrated offsets to HD 3651, a quiet star, we obtain residual velocities with an RMS of $<$70\,cm\,s$^{-1}$ in both the Red and Blue channels of MAROON-X over a baseline of 29 months. We also demonstrate the sensitivity of MAROON-X data calibrated with these offsets through a series of injection-recovery tests. Based on our findings, MAROON-X is capable of detecting sub m\,s$^{-1}$ signals out to periods of more than 1,000 days.

Planets are thought to form from dust and gas in protoplanetary disks, and debris disks are the remnants of planet formation. Aged a few Myr up to a few Gyr, debris disks have lost their primordial gas, and their dust is produced by steady-state collisions between larger, rocky bodies. Tens of debris disks, with sizes of tens, sometimes hundreds of au, have been resolved with high spatial resolution, high contrast imagers at optical/near-IR or (sub)-millimeter interferometers. They commonly show cavities, ring-like structures, and gaps, which are often regarded as indirect signatures of the presence of planets that gravitationally interact with unseen planetesimals. However, no planet responsible for these features has been detected yet, probably because of the limited sensitivity (typically 2-10 MJ) of high contrast imaging instruments prior to JWST. We have used the unprecedented sensitivity of JWST/MIRI in the thermal IR to search for such planets in the disk of the ~ 6.4 Myr old star TWA 7. With its pole-on orientation, this three-ring debris disk is indeed ideally suited for such a detection. We unambiguously detected a source 1.5 arsec from the star, that is best interpreted as a cold, sub-Jupiter mass planet. Its estimated mass (~ 0.3 MJ) and position (~ 52 au, de-projected) can thoroughly account for the main disk structures.

Semiconvection occurs in regions of stars and planets that are unstable to overturning convection according to the Schwarzschild criterion, yet stable according to the Ledoux criterion. Previous simulations in Cartesian boxes have advanced our understanding of the semiconvective instability, layer formation, and transport properties. However, much less is known about semiconvection in spherical geometry and under the influence of rotation or magnetic fields. We present 3D simulations of semiconvection in the full sphere (including $r=0$), and accounting for rotation. We find that the formation and evolution of semiconvective layers in nonrotating spheres occurs in a similar way to nonrotating Cartesian boxes, in the sense that the critical density ratio at which layers are expected to form is approximately the same in both geometries. Layers rapidly merge once they form, ultimately leading to a fully mixed convective sphere. The transport properties measured through the Nusselt numbers and the buoyancy flux ratio are also similar to results from previous studies in boxes. When rotation is added to the system, layer formation and evolution proceeds in a similar fashion to the nonrotating runs. However, rotation hampers the radial transport of heat and composition, and, as a result, the time required for the sphere to become fully mixed gets longer as the flow becomes more rotationally constrained. We also find that semiconvective layers exhibit spherical mixing in nonrotating cases, whereas in rotating cases, the mixing becomes more cylindrical. We discuss what is needed for future work to build more realistic models.

Context. Large-scale surveys across wavelengths, aided by machine learning, have improved the detection of old open clusters in high-extinction Milky Way regions. Aims. We aim to confirm or reject automatically detected open clusters in poorly studied, contaminated regions, refining samples for Galactic disk formation studies. Methods. Using VVVX, 2MASS, and Gaia DR3, we analyzed nine cluster candidates: BH118, BH144, Schuster-MWSC 1756, Saurer 3, FSR 1521, Saurer 2, Haffner 10-FSR 1231, Juchert 12, and Pismis 3. We examined density maps, proper motion diagrams, and photometry to derive physical parameters. Results. We identified star clusters via overdensities in 2MASS, WISE, and DECaPS, confirmed with VVVX and Gaussian Kernel Density Estimation. Using Gaia proper motions, we refined memberships, building a high-likelihood cluster catalog. We derived extinction ($A_{Ks} = 0.07$-$0.50$), color excess ($E(J-Ks) = 0.16$-$0.60$), distances ($D = 2.06$-$8.64$ kpc), and Galactocentric distances ($R_G = 7.69$-$14.81$ kpc). Ages range from 20 Myr to 5 Gyr, metallicity from [Fe/H] = -0.5 to 0.5. Structural parameters include core radii ($r_c = 0.71'$-$5.21'$) and tidal radii ($r_t = 3.4'$-$12.0'$). Conclusions. We confirm the open cluster nature of nine targets, updating their physical parameters.

We revisit the predictions of the nested leaky box model in detail, in terms of both primary cosmic-ray spectra, spectra of stable and unstable nuclei and antimatter production (positrons and antiprotons). We conclude that the model is in direct conflict with several observational facts and at least in its vanilla version should be considered as ruled out by current data. We also speculate on some possibly interesting implications of the idea that at least a fraction of Galactic grammage may not be accumulated in the journey of cosmic rays in the interstellar medium but rather inside the sources or in regions around them. These speculations will become increasingly more relevant with the higher precision data becoming available at high energies.

We report on Green Bank Telescope observations of the radio magnetar Swift J1818.0--1607 between 820 MHz and 35 GHz, taken from six to nine months after its 2020 March outburst. We obtained multi-hour observations at six frequencies, recording polarimetric, spectral, and single-pulse information. The spectrum peaks at a frequency of $5.4 \pm 0.6$ GHz, making Swift J1818.0--1607 one of many radio magnetars which exhibit a gigahertz-peaked spectrum (GPS). The radio flux decays steeply above the peak frequency, with in-band spectral indices $\alpha < -2.3 $ above 9 GHz. The emission is highly ($> 50\%$) linearly polarized, with a lower degree ($< 30\%$) of circular polarization which can change handedness between single pulses. Across the frequency range of our observations, the time-integrated radio profiles share a common shape: a narrow ``pulsar-like'' central component flanked by ``magnetar-like'' components comprised of bright, spiky subpulses. The outer profile components exhibit larger degrees of flux modulation and flatter spectral indices when compared to the central pulse component.

Abridged. Stochastic fluctuations in the spin frequency $\nu$ of a rotation-powered pulsar affect how accurately one measures the power-law braking index, $n_{\rm pl}$, defined through $\dot{\nu}=K\nu^{n_{\rm pl}}$, and can lead to measurements of anomalous braking indices, with $\vert n \vert = \vert \nu \ddot{\nu}/ \dot{\nu}^{2} \vert \gg1$, where the overdot symbolizes a derivative with respect to time. Previous studies show that the variance of the measured $n$ obeys the predictive, falsifiable formula $\langle n^{2} \rangle = n_{\rm pl}^{2}+\sigma^{2}_{\ddot{\nu}}\nu^{2}\gamma_{\ddot{\nu}}^{-2}\dot{\nu}^{-4}T_{\rm obs}^{-1}$ for $\dot{K}=0$, where $\sigma_{\ddot{\nu}}$ is the timing noise amplitude, $\gamma_{\ddot{\nu}}^{-1}$ is a stellar damping time-scale, and $T_{\rm obs}$ is the total observing time. Here we combine this formula with a hierarchical Bayesian scheme to infer the population-level distribution of $n_{\rm pl}$ for a pulsar population of size $M$. The scheme is validated using synthetic data. For a plausible test population with $M=100$ and injected $n_{\rm pl}$ values drawn from a population-level Gaussian with mean $\mu_{\rm pl}=4$ and standard deviation $\sigma_{\rm pl}=0.5$, intermediate between electromagnetic braking and mass quadrupole gravitational radiation reaction, the Bayesian scheme infers $\mu_{\rm pl}=3.89^{+0.24}_{-0.23}$ and $\sigma_{\rm pl}=0.43^{+0.21}_{-0.14}$. The $M=100$ per-pulsar posteriors for $n_{\rm pl}$ and $\sigma^{2}_{\ddot{\nu}}\gamma_{\ddot{\nu}}^{-2}$ contain $87\%$ and $69\%$, respectively, of the injected values within their $90\%$ credible intervals. Comparable accuracy is achieved for (i) population sizes spanning the range $50 \leq M \leq 300$, and (ii) wide priors satisfying $\mu_{\rm pl} \leq 10^{3}$ and $\sigma_{\rm pl} \leq 10^{2}$, which accommodate plausible spin-down mechanisms with $\dot{K}\neq0$.

We report a statistically significant detection of cumulative $\gamma$-ray emission from a stacked sample of SPT-SZ selected galaxy clusters using 16.4 years of data from the Fermi Gamma-Ray Space Telescope's Large Area Telescope (LAT). By analyzing a population of clusters with individual Test Statistic (TS) values $<$ 9.0, we identify a robust cumulative signal with a TS of 75.2, corresponding to approximately 8.4$\sigma$ significance. In contrast, clusters with TS $<$ 4.0 yield a weaker cumulative signal of TS = 9.65, consistent with background fluctuations. The derived $\gamma$-ray spectrum is well characterized by a power law model with a best-fit spectral index of $-2.59 \pm 0.20$ and an integrated flux of $1.67^{+1.35}_{-1.07} \times 10^{-11}$ ph cm$^{-2}$ s$^{-1}$. The spectral index matches hadronic cosmic-ray interaction predictions but may also include contributions from AGNs within the galaxy clusters.

Context. The sources of high-energy astrophysical neutrinos remain largely unknown. Multi-wavelength observational campaignshave identified a few plausible candidates, but their numbers are limited. Aims. We search for an excess of high-energy neutrino events originating from the directions of blazar sources, compared to the expected background. Additionally, we investigate blazars located within a small angular distance from the arrival directions of high-energy neutrinos, analyzing their characteristics to assess their plausibility as neutrino sources. Methods. We generate random samples of events following the right ascension and the declination distributions of the high-energy neutrino events detected by the IceCube Neutrino Observatory and count the coincidences of generated samples as well as the true observations with the Fermi-LAT blazar sources. Furthermore, we conduct temporal analysis of gamma-ray light curves and spectral analysis of blazar sources with the highest clustering of neutrino events. Results. We find an excess of high-energy neutrino events from the directions of Fermi blazars beyond random coincidence, with a significance of 2.42$\sigma$. Among the nine blazars which have a maximum number of neutrino events (four) arriving from within 3 degrees from them, 4FGL J1012.3+0629 exhibits the most significant variability around the neutrino detection time. Our study identifies 4FGL J1012.3+0629, 4FGL J2118.0+0019, 4FGL J2226.8+0051 and 4FGL J2227.9+0036 as plausible high-energy neutrino source candidates. The neutrino events IC110726A, IC170308A, IC190415A, IC141210A, IC150102A, IC230524A, IC140114A, IC110807A, and IC200523A likely originate from these sources. Additionally, we find that the spectral index tends to harden when these high-energy neutrino events are detected.

In this chapter we first describe the early history of primordial black hole (PBH) research. We then discuss their possible formation mechanisms, including critical collapse from inflationary fluctuations and various types of phase transition. We next describe the numerous constraints on the number density of PBHs from various quantum and astrophysical processes. This was the main focus of research until recently but there is currently a shift of emphasis to the search for evidence for PBHs. We end by discussing this evidence, with particular emphasis on their role as dark matter candidates, sources of gravitational waves and seeds for supermassive black holes and early cosmic structures.

Galaxy clusters are the largest self-gravitational systems in the Universe. They are valuable probes of the structure growth of the Universe when we estimate their peculiar velocities with the kinematic Sunyaev-Zel'dovich (kSZ) effects. We investigate whether there is a systematic offset between the peculiar velocities ($v_{\rm z,kSZ}$) estimated with the kSZ effect and the true velocities of halos. We first created mocks of the 2D maps of SZ effects in seven frequency bands for galaxy clusters spanning a broad range of masses in TNG 300-3. We then derived the line-of-sight (LOS) peculiar velocities of galaxy clusters by applying an analytical formula to fit the spectra of the SZ effect. We find that the analytical formula-fitting method tends to overestimate the peculiar velocities of galaxy clusters, regardless of whether they approach us or recede from us. However, when galaxy clusters larger than 500 km/s were excluded, the slopes of the relations between $v_{\rm z,kSZ}$ and the real LOS velocities of galaxy clusters ($v_{\rm z,halo}$) were consistent with unity within the errors. Additionally, we further accounted for observational noise for different-aperture telescopes under different precipitable water vapor. The slopes for most cases are consistent with unity within the errors, and the errors of the slopes slightly increase with higher observation noise. The $|v_{\rm z,kSZ}-v_{\rm z,halo}|$ exhibits no obvious trend with increasing concentration and $M_{\rm 200}$. It is noteworthy that the $|v_{\rm z,kSZ}-v_{\rm z,halo}|$ is relatively high for galaxy clusters with strong active galactic nucleus feedback and high star formation rates. This indicates that these physical processes affect the cluster dynamic state and may reflect on the peculiar velocity estimated from the kSZ effect.

In the case of Type-2 AGNs, estimating the mass of the black hole is challenging. Understanding how galaxies form and evolve requires considerable insight into the mass of black holes. This work compared different classical and quantum machine learning (QML) algorithms for black hole mass estimation, wherein the classical algorithms are Linear Regression, XGBoost Regression, Random Forest Regressor, Support Vector Regressor (SVR), Lasso Regression, Ridge Regression, Elastic Net Regression, Bayesian Regression, Decision Tree Regressor, Gradient Booster Regressor, Classical Neural Networks, Gated Recurrent Unit (GRU), LSTM, Deep Residual Networks (ResNets) and Transformer-Based Regression. On the other hand, quantum algorithms including Hybrid Quantum Neural Networks (QNN), Quantum Long Short-Term Memory (Q-LSTM), Sampler-QNN, Estimator-QNN, Variational Quantum Regressor (VQR), Quantum Linear Regression(Q-LR), QML with JAX optimization were also tested. The results revealed that classical algorithms gave better R^2, MAE, MSE, and RMSE results than the quantum models. Among the classical models, LSTM has the best result with an accuracy of 99.77%. Estimator-QNN has the highest accuracy for quantum algorithms with an MSE of 0.0124 and an accuracy of 99.75%. This study ascertains both the strengths and weaknesses of the classical and the quantum approaches. As far as our knowledge goes, this work could pave the way for the future application of quantum algorithms in astrophysical data analysis.

Double-peaked narrow emission lines (DPNELs) might be evidence for the existence of kpc-scale dual AGNs. There are so far large samples of objects with DPNELs in narrow emission line galaxies. Here, a systematic search is made to build a sample of type 1 AGNs with double-peaked [O~{\sc~iii}] from Data Release 16 of the Sloan Digital Sky Survey (SDSS). Through visually inspecting and fitting [O~{\sc~iii}], fitting broad H$\alpha$ emission lines, performing F-test for [O~{\sc~iii}] profiles, and checking broad H$\beta$ and [O~{\sc~iii}] emission lines, we select 62 type 1 AGNs with reliable double-peaked [O~{\sc~iii}] from 11557 QSOs with z < 0.3. After visually checking the 62 SDSS multi-color images, we find only seven objects with signs of merging. Four possible models for the double-peaked [O~{\sc~iii}] observed in our sample are discussed: the superposition model, AGN outflow model, dual AGN model, and rotating disk model. However, the current results can not provide any one explanation conclusively, and additional observational data are needed to provide the details of narrow line regions. But at least 22 objects with different velocity offsets between double-peaked [O~{\sc~iii}] and narrow H$\alpha$ emission lines could be excluded as dual AGN candidates. The relative velocity offsets of the [O~{\sc~iii}] blue-shifted/red-shifted components are negative to their line flux ratios, which is consistent with dual AGN model. This work provides a new sample of 62 type 1 AGNs with double-peaked [O~{\sc~iii}] for further study.

Machine learning (ML) has become a key tool in astronomy, driving advancements in the analysis and interpretation of complex datasets from observations. This article reviews the application of ML techniques in the identification and classification of stellar objects, alongside the inference of their key astrophysical properties. We highlight the role of both supervised and unsupervised ML algorithms, particularly deep learning models, in classifying stars and enhancing our understanding of essential stellar parameters, such as mass, age, and chemical composition. We discuss ML applications in the study of various stellar objects, including binaries, supernovae, dwarfs, young stellar objects, variables, metal-poor, and chemically peculiar stars. Additionally, we examine the role of ML in investigating star-related interstellar medium objects, such as protoplanetary disks, planetary nebulae, cold neutral medium, feedback bubbles, and molecular clouds.

Context. Magnetic fields exhibit a wide variety of behaviours in low mass stars and further characterization is required to understand these observations. Stellar photometry from space missions such as MOST, CoRoT, Kepler, and, in future PLATO, provide thousands of highly precise light curves (LC) that can shed new light upon stellar activity, in particular through the signature of transiting spots. Aims. We study the impact of star spots on light curves in the Fourier domain, reducing the degeneracies encountered by direct spot modelling in the temporal domain, and use this new formulation to explore the spot properties from the available data. Methods. We propose a model of LC power spectra at low frequency based on a description of spot transits that allows us to retrieve information about the amplitude of their photometric impact $\mathcal{H}$, and about the spot mean lifetime over the observation $\tau_{\rm life}$ when the power spectrum exibits rotation peaks. We first validate this method with simulated LCs and then apply it to the Kepler data to extract global trends over a set of more than 37 755 stars. Results. This analysis leads to a classification of the sample into "peakless" or "with peaks" spectra, and enables the identification of different activity regimes based on $\mathcal{H}$ and $\tau_{\rm life}$ for different ranges of Rossby number. More specifically, we observe an intense regime of activity between Ro = 0.7 and Ro = 1, for stars with masses under 1$M_\odot$. Conclusions. This new systematic method can be used to provide new observational constraints on stellar activity (and possibly a link with stellar magnetism) when applied to large photometric datasets, such as those from the future PLATO mission.

The astronomical origin of the most energetic galactic cosmic rays and gamma rays is still uncertain. X-ray followup of candidate "PeVatrons", systems producing cosmic rays with energies exceeding 1 PeV, can constrain their spatial origin, identify likely counterparts, and test particle emission models. Using 120 ks of XMM-Newton observations, we report the discovery of a candidate pulsar wind nebula, a possible counterpart for the LHAASO PeVatron J0343+5254u. This extended source has a power law X-ray spectrum with spectral index of 1.9 - softer at greater distance from the center - and asymmetric spatial extension out to 2'. We conduct leptonic modeling of the X-ray and gamma ray radiation from this complex system, showing that a fully leptonic model with elevated IR photon fields can explain the multiwavelength emission from this source, similar to other VHE pulsar wind nebulae; excess gamma ray emissivity not explained by a leptonic model may be due to hadronic interactions in nearby molecular cloud regions, which might also produce detectable astroparticle flux.

We report a new CO observation survey of LHAASO J0341$+$5258 using the Nobeyama Radio Observatory (NRO) 45-m telescope. LHAASO J0341$+$5258 is one of the unidentified ultra-high-energy (UHE; E $>$100 TeV) gamma-ray sources detected by LHAASO. Our CO observations were conducted in February and March 2024, with a total observation time of 36 hours, covering the LHAASO source ($\sim$0.3-0.5 degrees in radius) and its surrounding area (1$\times$1.5 degrees). Within the LHAASO source extent, we identified five compact ($<$ 2 pc) molecular clouds at nearby distances ($<$ 1-4 kpc). These clouds can serve as proton-proton collision targets, producing hadronic gamma rays via neutral pion decays. Based on the hydrogen densities (700-5000 cm$^{-3}$) estimated from our CO observations and archived HI data from the DRAO survey, we derived the total proton energy of $W_p$ (E $>$ 1 TeV) $\sim$ 10$^{45}$ erg to account for the gamma-ray flux. One of the molecular clouds appears to be likely associated with an asymptotic giant branch (AGB) star with an extended CO tail, which may indicate some particle acceleration activities. However, the estimated maximum particle energy below 100 TeV makes the AGB-like star unlikely to be a PeVatron site. We conclude that the UHE emission observed in LHAASO J0341$+$5258 could be due to hadronic interactions between the newly discovered molecular clouds and TeV-PeV protons originating from a distant SNR or due to leptonic emission from a pulsar wind nebula candidate, which is reported in our companion X-ray observation paper (DiKerby et al. 2025).

We investigate the inspiral of a high mass-ratio black hole binary located in the nucleus of a galaxy, where the primary central black hole is surrounded by a dense dark matter spike formed through accretion during the black hole growth phase. Within this spike, dark matter undergoes strong self-annihilation, producing a compact source of $\gamma$-ray radiation that is highly sensitive to spike density, while the binary emits gravitational waves at frequencies detectable by LISA. As the inspiralling binary interacts with the surrounding dark matter particles, it alters the density of the spike, thereby influencing the $\gamma$-ray flux from dark matter annihilation. We demonstrate that the spike self-annihilation luminosity decreases by $10\%$ to $90\%$ of its initial value, depending on the initial density profile and binary mass ratio, as the binary sweeps through the LISA band. This presents a new opportunity to indirectly probe dark matter through multi-messenger observations of galactic nuclei.

Measuring shock velocities is crucial for understanding the energy transfer processes at the shock fronts of supernova remnants (SNRs), including acceleration of cosmic rays. Here we present shock velocity measurements on the SNR N132D, based on the thermal properties of the shock-heated interstellar medium. We apply a self-consistent model developed in our previous work to X-ray data from deep Chandra observations with an effective exposure of $\sim$ 900 ks. In our model, both temperature and ionization relaxation processes in post-shock plasmas are simultaneously calculated, so that we can trace back to the initial condition of the shock-heated plasma to constrain the shock velocity. We reveal that the shock velocity ranges from 800 to 1500 $\rm{km~s^{-1}}$ with moderate azimuthal dependence. Although our measurement is consistent with the velocity determined by independent proper motion measurements in the south rim regions, a large discrepancy between the two measurements (up to a factor of 4) is found in the north rim regions. This implies that a substantial amount of the kinetic energy has been transferred to the nonthermal component through highly efficient particle acceleration. Our results are qualitatively consistent with the $\gamma$-ray observations of this SNR.

Astrophysical foreground substraction is crucial to retrieve the cosmic microwave background (CMB) polarization out of the observed data. Recent efforts have been carried out towards the development of a minimally informed component separation method to handle a priori unknown foreground spectral energy distributions (SEDs), while being able to estimate both cosmological, foreground, and potentially instrumental parameters, jointly. In this paper, we develop a semi-analytical performance forecasting framework for the minimally informed method and we validate it by comparing its results against direct sampling of the harmonic-based likelihood and the pixel domain implementation MICMAC. We then use the forecasting tool to demonstrate the robustness of the bias correction procedure introduced in the minimally informed approach. We find that a data-driven approach based on the currently available observational data is enough to efficiently regularize the bias of the method.

High redshift active galactic nuclei (AGN) provide key insights into early supermassive black hole growth and cosmic evolution. This study investigates the parsec-scale properties of 86 radio-loud quasars at z $\geq$ 3 using very long baseline interferometry (VLBI) observations. Our results show predominantly compact core and core-jet morphologies, with 35\% unresolved cores, 59\% core-jet structures, and only 6\% core-double jet morphology. Brightness temperatures are generally lower than expected for highly radiative sources. The jet proper motions are surprisingly slow compared to lower-redshift samples. We observe a high fraction of young and/or confined peak-spectrum sources, providing insights into early AGN evolution in dense environments during early cosmic epochs. The observed trends may reflect genuine evolutionary changes in AGN structure over cosmic time, or selection effects favoring more compact sources at higher redshifts. These results stress the complexity of high-redshift radio-loud AGN populations and emphasize the need for multi-wavelength, high-resolution observations to fully characterize their properties and evolution through cosmic history.

The EDE model is one of the promising solutions to the long-standing Hubble tension. This paper investigates the status of several EDE models in light of recent BAO observations from the Dark Energy Spectroscopic Instrument (DESI) and their implications for resolving the Hubble tension. The DESI Y1 BAO results deviate from the CMB and Type Ia supernova (SNeIa) observations in their constraints on the matter density $\Omega_m$ and the product of the sound horizon and the Hubble constant $r_s H_0$. Meanwhile, these EDE models happen to tend towards this deviation. Therefore, in this work, it is found that DESI Y1 BAO results strengthen the preference for EDE models and help to obtain a higher $H_0$. Even considering the Pantheon+ observations for SNeIa, which have an opposite tendency, DESI still dominates the preference for EDE. This was unforeseen in past SDSS BAO measurements and therefore emphasizes the role of BAO and SNeIa measurements in Hubble tension.

The mass function (MF) of young ($\mathrm{age\lesssim 200}$ Myr) stellar clumps is an indicator of the mechanism driving the collapse of the interstellar medium (ISM) into giant molecular clouds. Typically, the clump MF in main-sequence galaxies is described by a power law ($dN/dM_*\propto M_*^{-\alpha}$) with slope $\alpha=2$, hinting a turbulence-driven collapse. To understand whether the local environment affects star formation, we have modelled the clump MF of six cluster galaxies from the GASP survey, undergoing strong ram-pressure stripping. This process, exerted by the hot and high-pressure intra-cluster medium (ICM), has produced long tails of stripped ISM where clumps form far away from the galactic disk and surrounded by the ICM itself. Clumps were selected from HST-UVIS/WFC3 images, covering from near-UV to red-optical bands and including H$\alpha$-line maps. The catalogue comprises 398 H$\alpha$ (188 in tails, 210 in disk outskirts, the so-called extraplanar region) and 1270 UV clumps (593 tail, 677 extraplanar). Using mock images, we quantified the mass completeness and bias of our sample. Accounting for these two effects, we adopted a Bayesian approach to fit the clump mass catalogue to a chosen function. The resulting MFs are steeper than expected. In the tails, the H$\alpha$ clumps have slope $\alpha=2.31\pm0.12$, while the UV slope is larger ($2.60\pm0.09$), in agreement with ageing effects. Similar results are found in the extraplanar region, with H$\alpha$ slope $\alpha=2.45^{+0.20}_{-0.16}$ and UV slope $\alpha=2.63^{+0.20}_{-0.18}$, even if they are consistent within uncertainties. We suggest that the steepening results from the higher-than-usual turbulent environment, arising from the interaction between ISM and ICM. As shown by recent works, this process can favour the fragmentation of the largest ISM clouds, inhibiting the formation of very massive clumps.

Solar Energetic Particle (SEPs) with energies ranging from tens of keV to a few GeV, are a significant component in the description of the space environment. In this work, the HESPERIA REleASE product is emphasized, which, based on the Relativistic Electron Alert System for Exploration (REleASE) forecasting scheme, generates real-time predictions of the proton flux (30-50 MeV) at L1, making use of relativistic and near-relativistic electron measurements by the SOHO/EPHIN and ACE/EPAM experiments, respectively. The HESPERIA REleASE Alert is a notification system based on the forecasts produced by the HESPERIA REleASE product and informs about the expected radiation impact in real-time using an illustration and a distribution system for registered users. We also present and discuss the Advance Warning Times derived for the compiled list of major SEP events successfully forecasted over the last 2.5 years dur-ing solar cycle 25 by HESPERIA REleASE and recent developments.

Precise tracking of the growth in galaxy size and the evolution of merger fractions with redshift is vital for understanding the formation history of submillimeter galaxies (SMGs). This study investigates these evolutions over a broad redshift range ($1 < z \lesssim 6$), using a sample of 222 SMGs with a median redshift of $z = 2.61^{+0.89}_{-0.82}$ identified by ALMA and JCMT, enhanced by the advanced imaging capabilities of the JWST/NIRCam and MIRI. We find significant evolution in effective radii ($R_e$) in rest-frame V-band ($R_e \propto (1 + z)^{-0.87 \pm 0.08}$) and near-infrared (NIR) band ($R_e \propto (1 + z)^{-0.88 \pm 0.11}$), with the NIR size evolution resembling that of massive star-forming galaxies at lower redshift. Visual inspections reveal a major merger fraction of $24.3 \pm 3.7\%$ and an interaction fraction of up to $48.4 \pm 11.1\%$. The major merger fraction exhibits an increase from 14.7$\pm9.1$\% at $z = 1$ to 26.6$\pm 8.4$\% at $z = 3$, after which it remains approximately constant across the redshift range $3 < z < 6$. In contrast, the interaction fraction remains relatively stable across the range $2 < z < 5$. Our results indicate that late-stage major mergers are not the primary formation mechanism for SMGs at $z<3$, while interactions appear to play a significant role across the broader redshift range of $1<z<6$. Additionally, HST-based major merger identifications may overestimate the true fraction by a factor of 1.7 at $z \sim 2$. These findings highlight the varying roles of mergers and interactions in driving the formation of massive, dusty star-forming galaxies across different redshifts.

In this work, we establish fundamental relations, for the first time, in isolated systems in the local universe (with 0.005$\leq$z$\leq$0.080), which can give insight into the underlying physics of star-formation. We use a sample of isolated galaxies to explore whether star formation is regulated by smooth secular processes. In addition, galaxies in physically bound isolated pairs and isolated triplets may also interact with each other, where interaction itself may enhance/regulate star-formation and the distribution of gas and metals within galaxies. We made use of published emission line fluxes information from the Sloan Digital Sky Survey (SDSS) to identify SF galaxies in the SDSS-based catalogue of isolated galaxies (SIG), isolated pairs (SIP), and isolated triplets (SIT). We also use this data to derive their aperture-corrected SFR (considering two different methods) and oxygen abundance, 12 + log(O/H), using bright lines calibrations. Stellar masses for SIG, SIP, and SIT galaxies were estimated by fitting their spectral energy distribution on the five SDSS bands. We compared our results with a sample of SF galaxies in the SDSS. We found that, on average, at a fixed stellar mass, the SIG SF galaxies have lower SFR values than Main Sequence (MS) SF galaxies in the SDSS and central galaxies in the SIP and SIT. On average, SIG galaxies have higher 12 + log(O/H) values than galaxies in the SIP, SIT, and comparison sample. When distinguishing between central and satellite galaxies in the SIP and SIT, centrals and SIG galaxies present similar values ($\sim$8.55) while satellites have values close to M33 ($\sim$8.4). Based on our results, we propose a ground level `nurture' free SFR-M$_\star$ and gas metallicity-SFR-M$_\star$ relations for SF galaxies in the local universe.

We present a catalogue of extended radio sources from the SARAO MeerKAT Galactic Plane Survey (SMGPS). Compiled from 56 survey tiles and covering approximately 500 deg$^2$ across the first, third, and fourth Galactic quadrants, the catalogue includes 16534 extended and diffuse sources with areas larger than 5 synthesised beams. Of them, 3891 (24\% of the total) are confidently associated with known Galactic radio-emitting objects in the literature, such as HII regions, supernova remnants, planetary nebulae, luminous blue variables, and Wolf-Rayet stars. A significant fraction of the remaining sources, 5462 (33\%), are candidate extragalactic sources, while 7181 (43\%) remain unclassified. Isolated radio filaments are excluded from the catalogue. The diversity of extended sources underscores MeerKAT's contribution to the completeness of censuses of Galactic radio emitters, and its potential for new scientific discoveries. For the catalogued sources, we derived basic positional and morphological parameters, as well as flux density estimates, using standard aperture photometry. This paper describes the methods followed to generate the catalogue from the original SMGPS tiles, detailing the source extraction, characterisation, and crossmatching procedures. Additionally, we analyse the statistical properties of the catalogued populations

The Multiple Amplifier Sensing Charge-Coupled Device (MAS-CCD) has emerged as a promising technology for astronomical observation, quantum imaging, and low-energy particle detection due to its ability to reduce the readout noise without increasing the readout time as in its predecessor, the Skipper-CCD, by reading out the same charge packet through multiple inline amplifiers. Previous works identified a new parameter in this sensor, called the Node Removal Inefficiency (NRI), related to inefficiencies in charge transfer and residual charge removal from the output gates after readout. These inefficiencies can lead to distortions in the measured signals similar to those produced by the charge transfer inefficiencies in standard CCDs. This work introduces more details in the mathematical description of the NRI mechanism and provides techniques to quantify its magnitude from the measured data. It also proposes a new operation strategy that significantly reduces its effect with minimal alterations of the timing sequences or voltage settings for the other components of the sensor. The proposed technique is corroborated by experimental results on a sixteen-amplifier MAS-CCD. At the same time, the experimental data demonstrate that this approach minimizes the NRI effect to levels comparable to other sources of distortion the charge transfer inefficiency in scientific devices.

Stellar streams are remnants of globular clusters or dwarf galaxies that have been tidally disrupted by the gravitational potential of their host galaxy. Streams originating from dwarfs can be particularly compelling targets for indirect dark matter (DM) searches, as dwarfs are believed to be highly DM-dominated systems. Although these streams are expected to lose most of their DM during the tidal stretching process, a significant amount may still remain in their core. If DM is composed of WIMPs, their annihilation within the streams' cores could produce a detectable gamma-ray signal. In this study, we analyze nearly 15 years of data from the Large Area Telescope aboard NASA's Fermi satellite (Fermi-LAT) to search for potential WIMP annihilation signals from the direction of 11 stellar streams selected using DM-motivated criteria. No gamma-ray emission is detected from any of the streams in our sample. In the absence of a signal, we place the first constraints on the WIMP parameter space based on these objects for two representative annihilation channels. Individual DM limits are first computed and then combined across all streams. The most reliable combined constraints, derived from a golden sample and using a benchmark description of their DM content, are $O(10)$ times above the thermal relic cross-section for the $bb$ and $\tau^+\tau^-$ annihilation channels. We also explore how these constraints vary under more conservative or optimistic yet realistic assumptions, finding variations of up to a few orders of magnitude. This large systematic uncertainty stems from key model limitations, which can and should be addressed in future observations and simulations to produce more robust DM limits from streams. Despite uncertainties, this study demonstrates the feasibility of using stellar streams for DM searches and highlights their significant potential to uncover the properties of DM particles.

The visible and infrared Moon And Jupiter Imaging Spectrometer (MAJIS), aboard the JUpiter ICy Moons Explorer (JUICE) spacecraft, will characterize the composition of the surfaces and atmospheres of the Jupiter system. Prior to the launch, a campaign was carried out to obtain the measurements needed to calibrate the instrument. The aim was not only to produce data for the calculation of the radiometric, spectral, and spatial transfer functions, but also to evaluate MAJIS performance, such as signal-to-noise ratio and amount of straylight, under near-flight conditions. Here, we first describe the setup implemented to obtain these measurements, based on five optical channels. We notably emphasize the concepts used to mitigate thermal infrared emissions generated at ambient temperatures, since the MAJIS spectral range extends up to 5.6 $\mu$m. Then, we characterize the performance of the setup by detailing the validation measurements obtained before the campaign. In particular, the radiometric, geometric, and spectral properties of the setup needed for the inversion of collected data and the calculation of the instrument's calibration functions are presented and discussed. Finally, we provide an overview of conducted measurements with MAJIS, and we discuss unforeseen events encountered during the on-ground calibration campaign.

The topic of this talk is a new inflationary model in the context of Type IIB string compactifications called Loop Blow-Up Inflation, presented in arXiv:2403.04831. The original Blow-Up Inflation model, whose potential was purely non-perturbative, suffers from the $\eta$-problem, being sensitive to string-loop corrections. If these corrections are introduced in the nflationary potential, they become dominant over the non-perturbative contributions as soon as the inflaton is displaced from its minimum. Therefore, the inflationary potential takes a new inverse-power law behavior. We show that slow-roll inflation is not ultimately spoiled and focus on the post-inflationary history in different scenarios of microscopic Standard Model (SM) realization. Each of them gives precise predictions for the spectral index and the tensor-to-scalar ratio in agreement with CMB data .The model also predicts an amount of dark radiation potentially observable by next-generation CMB experiments. This article is a contribution to the proceedings of the Second General Meeting of the COST Action CA21106 Cosmic WISPers.

Large primordial lepton flavor asymmetries with almost vanishing total baryon-minus-lepton number can evade the usual BBN and CMB constraints if neutrino oscillations lead to perfect flavor equilibration. Solving the momentum averaged quantum kinetic equations (QKEs) describing neutrino oscillations and interactions, we perform the first systematic investigation of this scenario, uncovering a rich flavor structure in stark contradiction to the assumption of simple flavor equilibration. We find (i) a particular direction in flavor space, $\Delta n_e \simeq -2/3 \, (-1) \Delta n_\mu$ for normal (inverted) neutrino mass hierarchy, in which the flavor equilibration is efficient and primordial asymmetries are essentially unconstrained, (ii) a minimal washout factor, $\Delta n_e^2|_\mathrm{BBN} \leq 0.03 \, (0.016) \sum_\alpha \Delta n_\alpha^2|_{\mathrm{ini}}$ yielding a conservative estimate for the allowed primordial asymmetries in a generic flavor direction, and (iii) particularly strong or weak washout if one of the initial flavor asymmetries vanishes due to non-adiabatic muon- or electron-driven MSW transitions. These results open up the possibility of a first-order QCD phase transition facilitated by large lepton asymmetries as well as baryogenesis from large and compensated $\Delta n_e =- \Delta n_\mu$ asymmetries. Our first-principles approach of deriving momentum averaged QKEs includes collision terms beyond the damping approximation, energy transfer between the neutrino and electron-photon plasma, and provides a fast and reliable way to investigate the impact of primordial lepton asymmetries at the time of BBN. We publicly release the Mathematica code COFLASY-M on GitHub which solves the QKEs numerically.

Why matter and dark matter contents of the universe are of the same order of magnitude, is one of the puzzles of modern cosmology. At the face of it, this would seem to point towards a basic similarity between matter and dark matter, suggesting perhaps the widely discussed mirror world picture as an ideal setting for a discussion of this issue. Here we outline a new and simple mirror world scenario to explain this puzzle. Our model uses Affleck-Dine mechanism to generate baryon asymmetry and dark matter relic density leading to an asymmetric dark matter picture. We find that for a certain parameter range of the model, the mirror electron is the unique possibility for dark matter whereas in the complementary parameter range, the mirror baryons constitute the dark matter. In either case, the mirror photon must have mass in the MeV range for consistency with observations. For the case of mirror electron dark matter, the model predicts a lower bound on the amount of dark radiation i.e. $\Delta N_{eff} \geq 0.007$.

In 1998 Carlip and Solodukhin independently conjectured the equality between fluctuations in the modular Hamiltonian of black holes and its expectation value. Banks and Zurek's 2021 work generalized this observation to any causal diamonds. We use this observation to calculate the precise normalization of primordial scalar and tensor power spectra in the Holographic Space-time (HST) model of inflation. In previous work Banks and Fischler outlined the general calculation of inflationary power spectra in this model, which we review here. Its conceptual basis is radically different from field theoretic inflation and it has no Transplanckian problems, but its predictions for power spectra will be shown to fit extant data equally well, and the tensor-to-scalar ratio agrees with experimental observations. A brief presentation can be found on the Strings 2025 YouTube channel this https URL

This talk is based on the collaboration with Sergei D. Odintsov. We investigate the correspondence between modified gravity theories and general entropic cosmology theory. Such a theory is proposed by an analogy with Jacobson's work, where the Einstein equation was derived from the Bekenstein-Hawking entropy. We compare FLRW equations obtained in entropic gravity with those in modified gravity theories. It is found the correspondence of $F(T)$ and $F(Q)$ gravities and general entropic gravity. We regard the $F(T)$ and $F(Q)$ gravity theories as effective local theories corresponding to the entropic gravity theories and we investigate the gravitational waves. The obtained equation of the gravitational wave is identical to that in Einstein's gravity except that the gravitational coupling is modified by the functional form of the functions $F(T)$ and $F(Q)$. It is interesting that in the case of the Tsallis entropic cosmology, the gravitational coupling becomes small or large, which may suppress or enhance the emission of the gravitational wave.

We introduce TemplateGeNN, a fast stochastic template bank generation algorithm which uses Graphical Processing Units (GPUs) and a LearningMatch model (Siamese neural network). TemplateGeNN generated a binary black hole template bank (chirp mass varied from $5 M_{\odot} \leq \mathcal{M}_{c} \leq 20M_{\odot}$, symmetric mass ratio varied from $0.1 \leq \eta \leq 0.24999$, and equal aligned spin varied from $-0.99 \leq \chi_{1,2}\leq 0.99$) of 31,640 templates in $\sim 1$ day on a single A100 GPU. To test the sensitivity of this template bank we injected 7746 binary black hole templates into LIGO Gaussian noise. This template bank recovered 98$\%$ of the injections with a fitting factor greater than 0.97. For lower mass regions (black hole mass region between $5 M_{\odot} \leq m_{1, 2} \leq 25 M_{\odot}$), 99$\%$ of 9469 injections were recovered with a fitting factor greater than 0.97. LearningMatch and TemplateGeNN are a machine-learning pipeline that can be used to accelerate template bank generation for future gravitational-wave data analysis.

This paper investigates realistic anisotropic matter configurations for spherical symmetry in the framework of $f(R)$ gravity. The solutions obtained from Buchdahl-I metric are used to determine the behavior of PSR J0740+6620, PSR J0348+0432 and 4U 1608-52 with Starobinsky model. Analysis of physical parameters such as density, pressure, and anisotropy is illustrated through graphs, and the stability of compact objects is investigated by energy and causality conditions. We will also discuss the behavior of gravitational, hydrostatic and anisotropic forces, gravitational redshift and adiabatic index. At the theoretical and astrophysical scales, the graphical representations validate the practical and realistic $f(R)$ gravity models.

We analyze the effect of a variation of the strange nucleon matrix element $\langle N| m_s \bar{s}s|N\rangle$ on the abundances of the light elements produced in the Big Bang. For that, we vary the nucleon mass in the leading eight reactions that involve neutrons, protons and the four lightest nuclei. We use various available Big Bang nucleosynthesis codes and find that the measured deuterium and $^4$He abundances set strict limits on the nucleon mass variations. This translates into an upper bound of possible variations of the strange quark mass, $\left| \Delta m_s/m_s \right| \leq 5.1\%$.

We consider the revised Deser-Woodard model of nonlocal gravity by reformulating the related field equations within a suitable tetrad frame. This transformation significantly simplifies the treatment of the ensuing differential problem while preserving the characteristics of the original gravitational theory. We then focus on static and spherically symmetric spacetimes in vacuum. Hence, we demonstrate that the gravitational theory under study admits a class of black hole solutions characterized by an inverse power-law correction to the Schwarzschild $g_{tt}$ metric function and a first-order perturbation of the $g_{rr}$ Schwarzschild component. Then, through a stepwise methodology, we analytically solve the full dynamics of the theory, finally leading to the reconstruction of the nonlocal distortion function, within which the new black hole solutions arise. Furthermore, we analyze the geometric properties of the obtained solutions and quantify the deviations from the Schwarzschild prediction. This work provides new insights into compact object configurations and advances our understanding of nonlocal gravity theories in the strong-field regime at astrophysical scales.

We discuss certain astrophysical implications of the photon mass. It offers a new mechanism of black hole magnetization, described as ``vortextrap magnetization" (VTM), which can generate a near-saturated magnetic field in astrophysical black holes. The extreme magnetic field is provided by a large number of Nielsen-Olesen type vortex lines piercing a black hole. In massive photon scenario the galactic magnetic field is a densely populated forest of overlapping magnetic flux tubes. These get trapped and collected by a black hole over a cosmological time-scale. The VTM mechanism neatly fits supermassive black holes with sizes matching the phenomenologically-acceptable values of the photon mass, and has implications for magnetic-field based particle acceleration. Even in absence of surrounding plasma, the near-saturated magnetic field is expected to result into an intense electromagnetic radiation as well as gravitational waves in black hole mergers. We provide a numerical simulation of the VTM phenomenon in a prototype system.

The master equation of the Proca field in the Schwarzschild spacetime is studied by using the Seiberg-Witten/quasinormal modes duality. We establish the dictionary between the parameters in gauge and gravity theories, since both sides lead to Heun-type equations. Applying the technique of instanton counting, we analytically find the eigenfrequencies of the quasinormal modes and quasi-bound states for massive vector fields around black holes, with the boundary conditions linked by the connection formula. The results show consistency with known numerical researches in the literature.