Papers for Wednesday, Apr 03 2024

This paper implements likelihood-based jump detection for detectors read out up-the-ramp, using the entire set of reads to compute likelihoods. The approach compares the $\chi^2$ value of a fit with and without a jump for every possible jump location. I show that this approach can be substantially more sensitive than one that only uses the difference between sequential groups of reads, especially for long ramps and for jumps that occur in the middle of a group of reads. It can also be implemented for a computational cost that is linear in the number of resultants. I provide and describe a pure Python implementation that can process a 10-resultant ramp on a $4096 \times 4096$ detector in $\approx$20 seconds, including iterative cosmic ray detection and removal, on a single core of a 2020 Macbook Air. This Python implementation, together with tests and a tutorial notebook, are available at \url{https://github.com/t-brandt/fitramp}. I also provide tests and demonstrations of the full ramp fitting and cosmic ray rejection approach on data from JWST.

Despite being a fundamental property of galaxies that dictates the form of the potential, the 3D shape is intrinsically difficult to determine from observations. The improving quality of triaxial modeling methods in recent years has made it possible to measure these shapes more accurately. This study provides a comprehensive understanding of the stellar and dark matter (DM) shapes of galaxies and the connections between them as well as with other galaxy properties. Using the hydrodynamical cosmological simulation Magneticum Box4, we computed the stellar and DM shapes of galaxies at different radii. We determined their morphologies, their projected morphological and kinematic parameters, and their fractions of in-situ formed stars. The DM follows the stellar component in shape and orientation at $3R_{1/2}$, indicating that DM is heavily influenced by the baryonic potential in the inner parts of the halo. The outer DM halo is independent of the inner properties such as morphology, however, and is more closely related to the large-scale anisotropy of the gas inflow. The stellar shapes of galaxies are correlated with morphology: ellipticals feature more spherical and prolate shapes than disk galaxies. Galaxies with more rotational support are flatter, and the stellar shapes are connected to the mass distribution. In particular, more extended elliptical galaxies have larger triaxialities. Finally, the shapes can be used to constrain the in-situ fraction of stars when combined with the stellar mass. The found relations show that shapes depend on the details of the accretion history. The similarities between the inner DM and stellar shapes signal the importance of baryonic matter for DM in galaxies and will help improve dynamical models in the future. At large radii the DM shape is completely decoupled from the central galaxy and is coupled more to the large-scale inflow.

We use a cosmological zoom-in simulation of a Milky Way-like galaxy to study and quantify the topology of magnetic field lines around cold gas clouds in the circumgalactic medium (CGM). This simulation is a new addition to Project GIBLE, a suite of cosmological magnetohydrodynamical simulations of galaxy formation with preferential super-Lagrangian refinement in the CGM, reaching an unprecedented (CGM) gas mass resolution of $\sim$ $225$ M$_\odot$. To maximize statistics and resolution, we focus on a sample of $\sim$ $200$ clouds with masses of $\sim$ $10^6$ M$_\odot$. The topology of magnetic field lines around clouds is diverse, from threading to draping, and there is large variation in the magnetic curvature ($\kappa$) within cloud-background interfaces. We typically find little variation of $\kappa$ between upstream and downstream cloud faces, implying that strongly draped configurations are rare. In addition, $\kappa$ correlates strongly with multiple properties of the interface and the ambient background, including cloud overdensity and relative velocity, suggesting that cloud properties impact the topology of interface magnetic fields.

We conduct an in-depth spectral analysis of $\sim1{\rm ~Ms}$ XMM-Newton data of the narrow line Seyfert 1 galaxy RE J1034+396. The long exposure ensures high spectral quality and provides us with a detailed look at the intrinsic absorption and emission features toward this target. Two warm-absorber (WA) components with different ionization states ($\log (\xi/{\rm erg~cm~s}^{-1}) \sim 4$ and $\log (\xi/{\rm erg~cm~s}^{-1}) \sim 2.5-3$) are required to explain the intrinsic absorption features in the RGS spectra. The estimated outflow velocities are around $-1400{\rm ~km~s}^{-1}$ and $-(100-300){\rm ~km~s}^{-1}$ for the high- and low-ionization WA components, respectively. Both absorbers are located beyond the broad-line region and cannot significantly affect the host environment. We analyze the warm absorbers in different flux states. We also examine the May-2007 observation in the low and high phases of quasi-periodic oscillation (QPO). In contrast to previous analyses showing a negative correlation between the high-ionization WA and the QPO phase, we have found no such variation in this WA component. We discover a broad emission bump in the spectral range of $\sim12-18$ Angstrom, covering the primary features of the high-ionization WA. This emission bump shows a dramatic change in different source states, and its intensity may positively correlate with the QPO phase. The absence of this emission bump in previous work may contribute to the suggested WA-QPO connection.

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift-scan interferometer designed to map the entire northern sky every 24 hours. The all-sky coverage and sensitivity to neutral hydrogen flux at intermediate redshifts makes the instrument a resource for other exciting science in addition to cosmology for which it was originally designed. Characterizing the contents of CHIME's beam-smoothed maps will aid in planning novel use-cases for the instrument, particularly those pertaining to galaxy evolution studies. Here, we demonstrate its utility for the study of the \ion{H}{i} content of stacked galaxy populations across environments. Focusing first on galaxy clusters, we use simulated data from the IllustrisTNG project to understand the relative contribution of objects that fall into CHIME's synthesized beam to the observed \ion{H}{i} flux using stacking analyses at a couple of representative redshifts. We find that there is an appreciable difference in the estimated stacked flux when galaxy clusters or cluster member galaxies are used as tracers compared to stacking on a general galaxy catalog. Stacking on galaxy clusters, we report that it is possible to recover an average $M_\mathrm{HI}$ for clusters as a function of redshift and selection criteria.

This work aims at assessing the impact of DM self-interactions on the properties of galaxy clusters. In particular, the goal is to study the angular dependence of the cross section by testing rare (large angle scattering) and frequent (small angle scattering) SIDM models with velocity-dependent cross sections. We re-simulate six galaxy cluster zoom-in initial conditions with a dark matter only run and with a full-physics setup simulations that includes a self-consistent treatment of baryon physics. We test the dark matter only setup and the full physics setup with either collisionless cold dark matter, rare self-interacting dark matter, and frequent self-interacting dark matter models. We then study their matter density profiles as well as their subhalo population. Our dark matter only SIDM simlations agree with theoretical models, and when baryons are included in simulations, our SIDM models substantially increase the central density of galaxy cluster cores compared to full-physics simulations using collisionless dark matter. SIDM subhalo suppression in full-physics simulations is milder compared to the one found in dark matter only simulations, because of the cuspier baryionic potential that prevent subhalo disruption. Moreover SIDM with small-angle scattering significantly suppress a larger number of subhaloes compared to large angle scattering SIDM models. Additionally, SIDM models generate a broader range of subhalo concentration values, including a tail of more diffuse subhaloes in the outskirts of galaxy clusters and a population of more compact subhaloes in the cluster cores.

Binaries in dense environments are traditionally classified as soft or hard based on their binding energy relative to the kinetic energy of surrounding stars. Heggie's law suggests that stellar encounters tend to soften soft binaries and harden hard binaries, altering their separations. However, interactions with gas in such environments can significantly modify this behavior. This study investigates the impact of gas on binary softening and its consequences. We find that gas interactions can actually harden binaries, extending the soft-hard boundary to larger separations. This introduces a "shielding radius" within which binaries are likely to harden due to gas interactions, surpassing the traditional soft-hard limit. Consequently, a notable portion of binaries initially classified as "soft" may become "hard" when both gas and stars are considered. We propose a two-stage formation process for hard binaries: initial soft binary formation, either dynamically or through gas-assisted capture, followed by gas-induced hardening before eventual disruption. In environments with low gas density but high gas content, the shielding radius could exceed the typical hard-soft limit by an order of magnitude, leading to a significant fraction of originally soft binaries effectively becoming hard. Conversely, in high gas-density environments, gas-induced hardening may dominate, potentially rendering the entire binary population hard. Gas hardening emerges as a crucial factor in shaping binary populations in gas-rich settings, such as clusters, star-forming regions, and possibly AGN disks. This highlights the complex interplay between gas dynamics and stellar interactions in binary evolution within dense environments.

Low density plasmas in curved spacetimes, such as those found in accretion flows around black holes, are challenging to model from first principles, owing to the large scale separation between the characteristic scales of the microscopic processes and large mean-free-paths comparable to the system sizes. Kinetic approaches become necessary to capture the relevant physics but lack the dynamic range to model the global characteristics of the systems. In this paper, we develop new covariant guiding center equations of motion for charges in general relativistic spacetimes that are computationally tractable. We decompose the particle motion into a fast gyration, which we integrate analytically and a slow drift of the guiding center, which can be solved numerically. We derive covariant conservation laws for the motions of the guiding centers and show, through a number of limiting cases, that the equations contain all known drift mechanisms. Finally, we present the general relativistic expressions for the various drift velocities in Schwarzschild spacetimes.

Draco dwarf Spheroidal galaxy (dSph) is one of the nearest and the most dark matter dominated satellites of the Milky Way. We obtained multi-epoch near-infrared (NIR, $JHK_s$) observations of the central region of Draco dSph covering a sky area of $\sim 21'\times21'$ using the WIRCam instrument at the 3.6-m Canada-France-Hawaii Telescope. Homogeneous $JHK_s$ time-series photometry for 212 RR Lyrae (173 fundamental-mode, 24 first-overtone, and 15 mixed-mode variables) and 5 Anomalous Cepheids in Draco dSph is presented and used to derive their period-luminosity relations at NIR wavelengths for the first-time. The small scatter of $\sim 0.05$~mag in these empirical relations for RR Lyrae stars is consistent with those in globular clusters and suggests a very small metallicity spread, up to $\sim0.2$~dex, among these centrally located variables. Based on empirically calibrated NIR period-luminosity-metallicity relations for RR Lyrae in globular clusters, we determined a distance modulus to Draco dSph of $\mu_\textrm{RRL} = 19.557 \pm 0.026$ mag. The calibrated $K_s$-band period-luminosity relations for Anomalous Cepheids in the Draco dSph and the Large Magellanic Cloud exhibit statistically consistent slopes but systematically different zero-points, hinting at possible metallicity dependence of $\sim-0.3$ mag~dex$^{-1}$. Finally, the apparent magnitudes of the tip of the red giant branch in $I$ and $J$ bands also agree well with their absolute calibrations with the adopted RR Lyrae distance to Draco. Our recommended $\sim1.5\%$ precise RR Lyrae distance, $D_\textrm{Draco} = 81.55 \pm 0.98 \textrm{(statistical)} \pm 1.17 \textrm{(systematic)}$~kpc, is the most accurate and precise distance to Draco dSph galaxy.

We have investigated the absorption shapes of atomic lines and H{\alpha} in RR Lyrae stars. We used the database of high resolution spectra gathered with the Las Campanas Observatory du Pont Telescope, analyzing a set of about 2700 short exposure spectra of 17 RRab and 5 RRc variables. To increase the signal-to-noise of the spectra for each star, we first co-added spectra in small photometric phase bins, and then co-added metallic line profiles in velocity space. The resulting line absorption shapes vary with photometric phase in a consistent manner for all RRab stars, while exhibiting no obvious phase-related variations for the RRc stars. We interpret these line profile variations in terms of velocity gradients in the photospheric layers that produce absorption line profiles. The H{\alpha} profiles are much broader, indicative of shock temperatures of order 100,000 K.

Future astrophysics missions will seek extraterrestrial life via transmission and direct imaging observations. To assess habitability and biosignatures, we need robust retrieval tools to analyze observed spectra, and infer surface and atmospheric properties with their uncertainties. We use a novel retrieval tool to assess accuracy in characterizing near-surface habitability and biosignatures via simulated transmission and direct imaging spectra, based on the Origins Space Telescope (Origins) and LUVOIR mission concepts. We assess our ability to discriminate between an Earth-like and a false-positive O$_3$ TRAPPIST-1 e with transmission spectroscopy. In reflected light, we assess the robustness of retrieval results to un-modeled cloud extinction. We find that assessing habitability using transmission spectra may be challenging due to relative insensitivity to surface temperature and near-surface H$_2$O abundances. Nonetheless, our order of magnitude H$_2$O constraints can discriminate extremely desiccated worlds. Direct imaging is insensitive to surface temperature and subject to the radius/albedo degeneracy, but this method proves highly sensitive to surface water abundance, achieving retrieval precision within 0.1% even with partial clouds. Concerning biosignatures, Origins-like transmission observations ($t=40$ hours) may detect the CO$_2$/CH$_4$ pair on M-dwarf planets and differentiate between biological and false positive O$_3$ using H$_2$O and abundant CO. In contrast, direct imaging observations with LUVOIR-A ($t=10$ hours) are better suited to constraining O$_2$ and O$_3$, and may be sensitive to wavelength-dependent water cloud features, but will struggle to detect modern Earth-like abundances of methane. For direct imaging, we weakly detect a stratospheric ozone bulge by fitting the near-UV wings of the Hartley band.

Photonic lantern nulling (PLN) is a method for enabling the detection and characterization of close-in exoplanets by exploiting the symmetries of the ports of a mode-selective photonic lantern (MSPL) to cancel out starlight. A six-port MSPL provides four ports where on-axis starlight is suppressed, while off-axis planet light is coupled with efficiencies that vary as a function of the planet's spatial position. We characterize the properties of a six-port MSPL in the laboratory and perform the first testbed demonstration of the PLN in monochromatic light (1569 nm) and in broadband light (1450 nm to 1625 nm), each using two orthogonal polarizations. We compare the measured spatial throughput maps with those predicted by simulations using the lantern's modes. We find that the morphologies of the measured throughput maps are reproduced by the simulations, though the real lantern is lossy and has lower throughputs overall. The measured ratios of on-axis stellar leakage to peak off-axis throughput are around 10^(-2), likely limited by testbed wavefront errors. These null-depths are already sufficient for observing young gas giants at the diffraction limit using ground-based observatories. Future work includes using wavefront control to further improve the nulls, as well as testing and validating the PLN on-sky.

We present a quantitative and statistical analysis of the molecular gas morphology in 73 nearby galaxies using high spatial resolution CO (J=2-1) data obtained from the Atacama Large Millimeter/submillimeter Array (ALMA) by the PHANGS large program. We applied three model-independent parameters: Concentration (C), Asymmetry (A), and Clumpiness (S) which are commonly used to parameterize the optical and infrared morphology of galaxies. We find a significant correlation between A and S, with a Spearman's rank correlation coefficient of 0.62 with a p-value of $4 \times 10^{-9}$. This suggests a higher abundance of molecular clumps (i.e. giant molecular cloud associations) in galaxies that display stronger distortion or biased large-scale molecular gas distribution. In addition, the analysis of the C parameter suggests high central molecular concentration in most barred spiral galaxies investigated in this study. Furthermore, we found a positive correlation between the length of the bar structure ($R_\mathrm{bar}/R_{25}$) and the C parameter, with a Spearman's rank correlation coefficient of 0.63 with a p-value of $3.8 \times 10^{-5}$ suggesting that larger bar structure can facilitate overall molecular gas transport and yield higher central concentration than galaxies with shorter bars. Finally, we offer a possible classification scheme of nearby disk galaxies which is based on the CAS parameters of molecular gas.

We present a framework to quantify the clustering of gravitational wave (GW) transient sources and measure their spatial cross-correlation with the large-scale structure (LSS) of the universe using the $k$-nearest neighbour ($k$NN) formalism. As a first application, we measure the nearest-neighbour distributions of 53 suitably selected Binary Black Hole (BBH) mergers detected in the first three observation runs of LIGO-Virgo-KAGRA and cross-correlate these sources with ~$1.7 \times 10^7$ galaxies and quasars from the WISE$\times$SuperCOSMOS all-sky catalogue. To determine the significance of the clustering signal while accounting for observational systematics in the GW data, we create 135 realisations of mock BBHs that are statistically similar to the observed BBHs but spatially unclustered. We find no evidence for spatial clustering or cross-correlation with LSS in the data and conclude that the present sky localisation and number of detections are insufficient to get a statistically significant clustering signal. Looking forward, the statistically large number of detections and the significant improvements in sky localisations expected from future observing runs of LIGO (including LIGO India) and the next generation of GW detectors will enable measurement of the BBH-LSS cross-correlation and open a new window into cosmology.

As the nearest confirmed Lyman continuum (LyC) emitter, Haro 11 is an exceptional laboratory for studying LyC escape processes crucial to cosmic reionization. Our new HST/COS G130M/1055 observations of its three star-forming knots now reveal that the observed LyC originates in Knots B and C, with $903 - 912~\r{A}$ luminosities of $1.9\pm1.5 \times 10^{40}~\rm erg~s^{-1}$ and $0.9\pm0.7 \times 10^{40}~\rm erg~s^{-1}$, respectively. We derive local escape fractions $f_{\rm{esc, 912}} = 3.4\pm2.9\%$ and $5.1\pm4.3\%$ for Knots B and C, respectively. Our Starburst99 modeling shows dominant populations on the order of $\sim1-4$ Myr and $1-2\times10^7 \rm~M_\odot$ in each knot, with the youngest population in Knot B. Thus, the knot with the strongest LyC detection has the highest LyC production. However, LyC escape is likely less efficient in Knot B than in Knot C due to higher neutral gas covering. Our results therefore stress the importance of the intrinsic ionizing luminosity, and not just the escape fraction, for LyC detection. Similarly, the Ly$\alpha$ escape fraction does not consistently correlate with LyC flux, nor do narrow Ly$\alpha$ red peaks. High observed Ly$\alpha$ luminosity and low Ly$\alpha$ peak velocity separation, however, do correlate with higher LyC escape. Another insight comes from the undetected Knot A, which drives the Green Pea properties of Haro 11. Its density-bounded conditions suggest highly anisotropic LyC escape. Finally, both of the LyC-leaking Knots, B and C, host ultra-luminous X-ray sources (ULXs). While stars strongly dominate over the ULXs in LyC emission, this intriguing coincidence underscores the importance of unveiling the role of accretors in LyC escape and reionization.

We perform the first magnetohydrodynamic simulation tracking the magnetosphere of a collapsing magnetar. The collapse is expected for massive rotating magnetars formed in merger events, and it may occur many hours after the merger. The results suggest a novel gamma-ray burst (GRB) scenario, which creates a delayed high- energy counterpart of the merger gravitational waves. The collapse launches an outgoing magnetospheric shock, and a hot magnetized outflow forms behind the shock. The outflow is modulated by the ring-down of the nascent black hole, imprinting its kilohertz quasi-normal modes on the GRB tail.

We explore the possibility of redshift-dependent deviations in the contribution of relativistic degrees of freedom to the radiation budget of the cosmos, conventionally parameterized by the effective number of neutrinos $N_{\rm eff}$, from the predictions of the standard model. We expand the deviations $\Delta N_{\rm eff}(z)$ in terms of top-hat functions and treat their amplitudes as the free parameters of the theory to be measured alongside the standard cosmological parameters by the Planck measurements of the cosmic microwave background (CMB) anisotropies and Baryonic Acoustic Oscillations, as well as performing forecasts for futuristic CMB surveys such as PICO and CMB-S4. We reconstruct the history of $\Delta N_{\rm eff}$ and find that with the current data the history is consistent with the standard scenario. Inclusion of the new degrees of freedom in the analysis increases $H_0$ to $68.71\pm 0.44$, slightly reducing the Hubble tension. With the smaller forecasted errors on the $\Delta N_{\rm eff}(z)$ parametrization modes from future CMB surveys, very accurate bounds are expected within the possible range of dark radiation models.

Very long baseline interferometry (VLBI) provides the highest-resolution images in astronomy. The sharpest resolution is nominally achieved at the highest frequencies, but as the observing frequency increases so too does the atmospheric contribution to the system noise, degrading the sensitivity of the array and hampering detection. In this paper, we explore the limits of high-frequency VLBI observations using ngehtsim, a new tool for generating realistic synthetic data. ngehtsim uses detailed historical atmospheric models to simulate observing conditions, and it employs heuristic visibility detection criteria that emulate single- and multi-frequency VLBI calibration strategies. We demonstrate the fidelity of ngehtsim's predictions using a comparison with existing 230 GHz data taken by the Event Horizon Telescope (EHT), and we simulate the expected performance of EHT observations at 345 GHz. Though the EHT achieves a nearly 100% detection rate at 230 GHz, our simulations indicate that it should expect substantially poorer performance at 345 GHz; in particular, observations of M87 at 345 GHz are predicted to achieve detection rates of $\lesssim$20% that may preclude imaging. Increasing the array sensitivity through wider bandwidths and/or longer integration times -- as enabled through, e.g., the simultaneous multi-frequency upgrades envisioned for the next-generation EHT -- can improve the 345 GHz prospects and yield detection levels that are comparable to those at 230 GHz. M87 and Sgr A* observations carried out in the atmospheric window around 460 GHz could expect to regularly achieve multiple detections on long baselines, but analogous observations at 690 and 875 GHz consistently obtain almost no detections at all.

Radio photons interact with anisotropic density fluctuations in the heliosphere, which can alter their trajectory and influence properties deduced from observations. This is particularly evident in solar radio observations, where anisotropic scattering leads to highly-directional radio emissions. Consequently, observers at varying locations will measure different properties, including different source sizes, source positions, and intensities. However, it is not known if measurements of the decay time of solar radio bursts are also affected by the observer's position. Decay times are dominated by scattering effects, and so are frequently used as proxies of the level of density fluctuations in the heliosphere, making the identification of any location-related dependence crucial. We combine multi-vantage observations of interplanetary Type III bursts from four non-collinear, angularly-separated spacecraft with simulations, to investigate the dependence of both the decay- and rise-time measurements on the separation of the observer from the source. We propose a function to characterise the entire time profile of radio signals, allowing for the simultaneous estimation of the peak flux, decay time, and rise time, while demonstrating that the rise phase of radio bursts has a non-constant, non-exponential growth rate. We determine that the decay and rise times are independent of the observer's position, identifying them as the only properties to remain unaffected, thus not requiring corrections for the observer's location. Moreover, we examine the ratio between the rise and decay times, finding that it does not depend on the frequency. Therefore, we provide the first evidence that the rise phase is also significantly impacted by scattering effects, adding to our understanding of the plasma emission process.

Decaying dark matter (DDM) can be tested via different astrophysical and cosmological probes. In particular, particles in the $\sim$ 9.5 - 30 eV mass range that decay into monochromatic photons, would contribute to the extragalactic background light (EBL) in the ultraviolet (UV) bandwidth. In this work, we show that an intriguing improvement to the constraints on such DDM models can come from broadband UV surveys, such as GALEX or the upcoming ULTRASAT satellite. These provide diffuse light maps of the UV EBL, integrated over a wide redshift range. The cross correlation between intensity fluctuations in these maps with a reference spectroscopic galaxy survey, can be used to reconstruct the redshift evolution of the EBL intensity; in this way, it is also possible to detect signatures of contributions from DDM. We forecast the constraining power of (GALEX+ULTRASAT)$\times$DESI, and we show they will be able to detect DDM with decay rate up to $\mathcal{O}(10^{-26}\,{\rm s})$. In the context of axion-like particles (ALP), our forecasts can be converted to constraints on the ALP-photon coupling; our results show this technique will test ALP with coupling $\lesssim\mathcal{O}(10^{-12}\,{\rm GeV^{-1}})$, more than an order of magnitude better than current bounds in this mass range.

"Everyone knows the moon is made of cheese..." This line, famously uttered by Wallace to his canine sidekick Gromit in the 80s classic, may be one of the most cruelly underappreciated movie quotations of our time. Indeed, while most scientists today would simply reject Wallace's claim as preposterous, we aim to revisit his theory on the composition of our natural satellite, revealing that it may not be as implausible as the scientific consensus would have it. Through a revelatory novel analysis of existing data, we will show that very simple cheese-based models can provide a convincing explanation of the Lunar surface's spectral characteristics in the near-infrared. Using the tried and tested PLS (Partial Least Squares) method, we efficiently and reliably retrieve the concentrations of various cheese types in different locations of the Lunar surface. Our results bring to light a bold and flavourful prediction about the Moon's composition, which lays the groundwork for an important paradigm shift in planetary sciences. We urge the scientific community to take a serious notice of this piquant novel interpretation, and strongly consider it in their future models of planetary composition and formation in our solar system and beyond.

The Hubble constant ($H_0$), a crucial parameter in cosmology, quantifies the expansion rate of the universe so its precise measurement is important to understand the fundamental dynamics of our evolving universe. One of the major limitations of measuring $H_0$ using time-delay cosmography is the presence of the mass-sheet degeneracy (MSD) in the lens mass modeling. We propose and quantitatively assess the use of galaxy-galaxy shear measurements to break the MSD in the strong lensing mass modeling. We use stacked galaxy-galaxy lensing profiles and corresponding covariance matrices from Huang et al. (2022) to constrain the MSD in lens mass modeling with a highly flexible mass profile. Our analyses show that if ideally all galaxy-galaxy lensing measurements from the Hyper Suprime-Cam (HSC) survey can be used to constrain the MSD, we can achieve $\sim 10\%$ precision on the MSD constraint. We forecast that galaxy-galaxy lensing measurements from LSST-like surveys can in general constrain the MSD with $\sim 1-3\%$ precision. Furthermore, if we push weak lensing measurements to a lower angular scale of $\sim 0.04$ $\rm Mpc$, a survey like LSST can provide $\sim 1\%$ precision on the MSD constraint, enabling a measurement of $H_0$ at the $1\%$ level. We demonstrate that galaxy-galaxy weak lensing can robustly constrain the MSD independent of stellar kinematics of the deflector, with wide-field survey data alone.

Relativistic plasmas around compact objects can sometimes be approximated as being force-free. In this limit, the plasma inertia is negligible and the overall dynamics is governed by global electric currents. We present a novel numerical approach for simulating such force-free plasmas, which allows for high accuracy in smooth regions as well as capturing dissipation in current sheets. Using a high-order accurate discontinuous Galerkin method augmented with a conservative finite-difference method, we demonstrate efficient global simulations of black hole and neutron star magnetospheres. In addition to a series of challenging test problems, we show that our approach can-depending on the physical properties of the system and the numerical implementation-be up to 10x more efficient than conventional simulations, with a speedup of 2-3x for most problems we consider in practice.

We studied the effects of cluster environments on galactic structures by using the TNG50 cosmological simulation and observed galaxies in the Fornax cluster. We focused on galaxies with stellar masses of $10^{8-12}M_{\odot}$ at z=0 that reside in Fornax-like clusters with total masses of $M_{200c} = 10^{13.4-14.3}M_{\odot}$. We characterized the stellar structures by decomposing each galaxy into a dynamically cold disk and a hot non-disk component, and studied the evolution of both the stellar and gaseous constituents. In TNG50, we find that the cold gas is quickly removed when a galaxy falls into a Fornax-mass cluster. About 87\% of the galaxies have lost $80\%$ of their star-forming gas at 4 billion years after infall, with the remaining gas concentrating in the inner regions of the galaxy. The radius of the star-forming gaseous disk decreases to half its original size at 4 billion years after infall for 66\% of the galaxies. As a result, star formation in the extended dynamically cold disk sharply decreases, even though a low level of SF persists at the center for a few additional gigayears. This leads to a tight correlation between the average stellar age in the dynamically cold disk and the infall time of galaxies. Furthermore, the luminosity fraction of the dynamically cold disk in ancient infallers is only about 1/3 of that in recent infallers, controlling for galaxy stellar mass. This quantitatively agrees with what is observed in early-type galaxies in the Fornax cluster. Gas removal stops the possible growth of the disk, with gas removed earlier in galaxies that fell in earlier, and hence the cold-disk fraction is correlated with the infall time. The stellar disk can be significantly disrupted by tidal forces after infall, through a long-term process that enhances the difference among cluster galaxies with different infall times.

Reconstructing the intrinsic Ly$\alpha$ line flux from high-$z$ QSOs can place constraints on the neutral hydrogen content of the intergalactic medium during reionisation. There are now $\gtrsim10$ different Ly$\alpha$ reconstruction pipelines using different methodologies to predict the Ly$\alpha$ line flux from correlations with the spectral information redward of Ly$\alpha$. However, there have been few attempts to directly compare the performance of these pipelines. Therefore, we devised a blind QSO challenge to compare these reconstruction pipelines on a uniform set of objects. Each author was provided de-identified, observed rest-frame QSO spectra with spectral information only redward of 1260\AA\ rest-frame to ensure unbiased reconstruction. We constructed two samples of 30 QSOs, from X-Shooter and SDSS both spanning $3.5<z<4.5$. Importantly, the purpose of this comparison study was not to champion a single, best performing reconstruction pipeline but rather to explore the relative performance of these pipelines over a range of QSOs with broad observational characteristics to infer general trends. In summary, we find machine learning approaches in general provide the strongest ``best guesses" but underestimate the accompanying statistical uncertainty, although these can be recalibrated, whilst pipelines that decompose the spectral information, for example principal component or factor analysis generally perform better at predicting the Ly$\alpha$ profile. Further, we found that reconstruction pipelines trained on SDSS QSOs performed similarly on average for both the X-Shooter and SDSS samples indicating no discernible biases owing to differences in the observational characteristics of the training set or QSO being reconstructed, although the recovered distributions of reconstructions for X-Shooter were broader likely due to an increased fraction of outliers.

In this chapter, we delve into the formation and primary characteristics of two significant components within galaxy clusters: the brightest cluster galaxies and the intracluster light. Drawing upon recent and pertinent studies in the field, we explore the mechanisms driving their growth from high redshift to the present day. We also examine how these formation mechanisms are intertwined with the dynamical state of their host clusters, suggesting their potential utility as luminous tracers of dark matter.

PyCPL provides full access to ESO's Common Pipeline Library ( CPL) for astronomical data reduction within a Python environment. Not only does it offer a Python interface to the robust CPL library, but it also lets users and developers fully utilise the rest of the scientific Python ecosystem. We have written a C++ layer to CPL and with pybind11 (a third-party library) created a Pythonic API to CPL. Since CPL has been around for so long, it has been thoroughly tested and understood. In 2003 it was developed in C due to its efficiency and speed of execution. With the community however moving away from C/C++ programming and embracing Python for data processing tasks, there is a need to provide access to the CPL utilities within a Python environment. With the latest version being released users can now install PyCPL to run existing CPL recipes (written in C) and access the results from Python. It also provides the ability to create new recipes in Python using the functionality provided by CPL.

Carbon isotope fractionation of CO has been reported in the disk around TW Hya,where elemental carbon is more abundant than elemental oxygen ([C/O]$_{\rm elem}$> 1). We investigated the effects of the [C/O]$_{\rm elem}$ ratio on carbon fractionation using astrochemical models that incorporate isotope-selective photodissociation and isotope-exchange reactions. The $^{12}$CO/$^{13}$CO ratio could be lower than the elemental carbon isotope ratio due to isotope exchange reactions when the [C/O]$_{\rm elem}$ ratio exceeds unity. The observed $^{12}$CO/$^{13}$CO and H$^{12}$CN/H$^{13}$CN ratios around TW Hya could be reproduced when the [C/O]$_{\rm elem}$ ratio is 2~5. In the vicinity of the lower boundary of the warm molecular layer, the formation of ices leads to the gas phase [C/O]$_{\rm elem}$ ratio approaching unity, irrespective of the total (gas + ice) [C/O]$_{\rm elem}$ ratio. This phenomenon reduces the variation in the $^{12}$CO/$^{13}$CO ratio across different [C/O]$_{\rm elem}$ ratios.

The Major Atmospheric Cherenkov Experiment (MACE) is a large size (21m) Imaging Atmospheric Cherenkov Telescope (IACT) installed at an altitude of 4270m above sea level at Hanle, Ladakh in northern India. Here we report the detection of Very High Energy (VHE) gamma-ray emission from Crab Nebula above 80 GeV. We analysed ~15 hours of data collected at low zenith angle between November 2022 and February 2023. The energy spectrum is well described by a log-parabola function with a flux of ~(3.46 +/- 0.26stat) x 10-10 TeV-1 cm-2 s-1, at 400 GeV with spectral index of 2.09 +/- 0.06stat and a curvature parameter of 0.08 +/- 0.07stat. The gamma-rays are detected in an energy range spanning from 80 GeV to ~5 TeV. The energy resolution improves from ~34% at an analysis energy threshold of 80 GeV to ~21% above 1 TeV. The daily light curve and the spectral energy distribution obtained for the Crab Nebula is in agreement with previous measurements, considering statistical and systematic uncertainties.

In this work we provide a new, well-controlled expansion of the equation of state of dense matter from zero to finite temperatures ($T$), while covering a wide range of charge fractions ($Y_Q$), from pure neutron to isospin symmetric nuclear matter. Our expansion can be used to describe neutron star mergers and core-collapse supernova explosions using as a starting point neutron star observations, while maintaining agreement with laboratory data, in a model independent way. We suggest new thermodynamic quantities of interest that can be calculated from theoretical models or directly inferred by experimental data that can help constrain the finite $T$ equation of state. With our new method, we can quantify the uncertainty in our finite $T$ and $Y_Q$ expansions in a well-controlled manner without making assumptions about the underlying degrees of freedom. We can reproduce results from a microscopic equation of state up to $T=100$ MeV for baryon chemical potential $\mu_B\gtrsim 1100$ MeV ($\sim1-2 \ n_{\rm sat}$) within $5\%$ error, with even better results for larger $\mu_B$ and/or lower $T$. We investigate the sources of numerical and theoretical uncertainty and discuss future directions of study.

Polarisation observations of masers in the circumstellar envelopes (CSEs) around Asymptotic Giant Branch (AGB) stars have revealed strong magnetic fields. However, masers probe only specific lines-of-sight through the CSE. Non-masing molecular line polarisation observation can more directly reveal the large scale magnetic field morphology and hence probe the effect of the magnetic field on AGB mass-loss and the shaping of the AGB wind. Observations and models of CSE molecular line polarisation can now be used to describe the magnetic field morphology and estimate its strength throughout the entire CSE. We use observations taken with ALMA of molecular line polarisation in the envelope of two AGB stars (CW~Leo and R~Leo). We model the observations using the multi-dimensional polarised radiative transfer tool PORTAL. We find linearly polarised emission, with maximum fractional polarisation on the order of a few percent, in several molecular lines towards both stars. We can explain the observed differences in polarisation structure between the different molecular lines by alignment of the molecules by a combination of the Goldreich-Kylafis effect and radiative alignment effects. We specifically show that the polarisation of CO traces the morphology of the magnetic field. Competition between the alignment mechanisms allows us to describe the behaviour of the magnetic field strength with radius throughout the circumstellar envelope of CW~Leo. The magnetic field strength derived using this method is inconsistent with the magnetic field strength derived using a structure function analysis of the CO polarisation and the strength previously derived using CN Zeeman observations. In contrast with CW~Leo, the magnetic field in the outer envelope of R~Leo appears to be advected outwards by the stellar wind. {abridged abstract}

Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris removal. Analyzing light curves to determine attitude is the most commonly used method. In photometric observations, outliers may exist in the obtained light curves due to various reasons. Therefore, preprocessing is required to remove these outliers to obtain high quality light curves. Through statistical analysis, the reasons leading to outliers can be categorized into two main types: first, the brightness of the object significantly increases due to the passage of a star nearby, referred to as "stellar contamination," and second, the brightness markedly decreases due to cloudy cover, referred to as "cloudy contamination." Traditional approach of manually inspecting images for contamination is time-consuming and labor-intensive. However, We propose the utilization of machine learning methods as a substitute. Convolutional Neural Networks (CNN) and Support Vector Machines (SVM) are employed to identify cases of stellar contamination and cloudy contamination, achieving F1 scores of 1.00 and 0.98 on test set, respectively. We also explored other machine learning methods such as Residual Network-18 (ResNet-18) and Light Gradient Boosting Machine (lightGBM), then conducted comparative analyses of the results.

Gaia mission offers opportunities to search for compact binaries not involved in binary interactions (hereafter inert compact binaries), and results in the discoveries of binaries containing one black hole (BH) or one neutron star (NS), called ``Gaia BHs'' and ``Gaia NSs'', respectively. We have assessed if Gaia BHs and NSs can be formed in open clusters through dynamical interactions. In order to obtain a large number of inert compact binaries similar to Gaia BHs and NSs, we have performed gravitational $N$-body simulations for a large number of open clusters whose total mass is $1.2 \times 10^8 M_\odot$. These clusters have various masses, metallicities, densities, and binary fractions. We have found that open clusters form Gaia BHs ($10^{-6}$-$10^{-5} M_\odot^{-1}$) much more efficiently than Gaia NSs ($\lesssim 10^{-7} M_\odot^{-1}$) for any cluster parameters. This is quite inconsistent with observational results, because the reported numbers of Gaia BHs and NSs are $2$ and $\sim 20$, respectively. Additionally, we have switched off NS natal kicks for $10^4$ open clusters each weighing $10^3 M_\odot$ in order to retain a large number of NSs in open clusters. Then, open clusters form inert NS binaries originating from primordial binaries rather than formed through dynamical interactions. This means that Gaia NSs are formed dominantly on isolated fields, not in open clusters, if there is no NS natal kick. We have concluded that Gaia BHs can be dominantly formed in open clusters, however Gaia NSs cannot.

Understanding the explosion mechanism and hydrodynamic evolution of core-collapse supernovae is a long-standing quest in astronomy. The asymmetries caused by the explosion are encoded into the line profiles which appear in the nebular phase of the SN evolution -- with particularly clean imprints in He star explosions. Here, we carry out nine different supernova simulations of He-core progenitors, exploding them in 3D with parametrically varied neutrino luminosities using the $\texttt{Prometheus-HotB}$ code, hydrodynamically evolving the models to the homologeous phase. We then compute nebular phase spectra with the 3D NLTE spectral synthesis code $\texttt{ExTraSS}$ (EXplosive TRAnsient Spectral Simulator). We study how line widths and shifts depend on progenitor mass, explosion energy, and viewing angle. We compare the predicted line profile properties against a large set of Type Ib observations, and discuss the degree to which current neutrino-driven explosions can match observationally inferred asymmetries. With self-consistent 3D modelling -- circumventing the difficulties of representing $^{56}$Ni mixing and clumping accurately in 1D models -- we find that neither low-mass He cores exploding with high energies nor high-mass cores exploding with low energies contribute to the Type Ib SN population. Models which have line profile widths in agreement with this population give sufficiently large centroid shifts for calcium emission lines. Calcium is more strongly affected by explosion asymmetries connected to the neutron star kicks than oxygen and magnesium. Lastly, we turn to the NIR spectra from our models to investigate the potential of using this regime to look for the presence of He in the nebular phase.

The MHONGOOSE (MeerKAT HI Observations of Nearby Galactic Objects: Observing Southern Emitters) survey maps the distribution and kinematics of the neutral atomic hydrogen (HI) gas in and around 30 nearby star-forming spiral and dwarf galaxies to extremely low HI column densities. The HI column density sensitivity (3 sigma over 16 km/s) ranges from ~ 5 x 10^{17} cm^{-2} at 90'' resolution to ~4 x 10^{19} cm^{-2} at the highest resolution of 7''. The HI mass sensitivity (3 sigma over 50 km/s) is ~5.5 X 10^5 M_sun at a distance of 10 Mpc (the median distance of the sample galaxies). The velocity resolution of the data is 1.4 km/s. One of the main science goals of the survey is the detection of cold, accreting gas in the outskirts of the sample galaxies. The sample was selected to cover a range in HI masses, from 10^7 M_sun to almost 10^{11} M_sun, to optimally sample possible accretion scenarios and environments. The distance to the sample galaxies ranges from 3 to 23 Mpc. In this paper, we present the sample selection, survey design, and observation and reduction procedures. We compare the integrated HI fluxes based on the MeerKAT data with those derived from single-dish measurement and find good agreement, indicating that our MeerKAT observations are recovering all flux. We present HI moment maps of the entire sample based on the first ten percent of the survey data, and find that a comparison of the zeroth- and second-moment values shows a clear separation between the physical properties of the HI in areas with star formation and areas without, related to the formation of a cold neutral medium. Finally, we give an overview of the HI-detected companion and satellite galaxies in the 30 fields, five of which have not previously been catalogued. We find a clear relation between the number of companion galaxies and the mass of the main target galaxy.

We conduct a systematic study on the light curves of type II supernovae (SNe II) to investigate how they are affected by the physical properties of the progenitor and the nature of the explosion. The calculations of pre-supernova evolution, the launch of the explosion, and the light curve are carried out by \texttt{MESA} and \texttt{STELLA}. Our study encompasses a wide range of zero-age-main-sequence (ZAMS) masses (10 - 20 $M_{\rm \odot}$), wind mass-loss rates (which control the range of hydrogen-rich envelope mass to be 3 - 12 $M_{\rm \odot}$), explosion energies (0.1 - 2.5 $\times$ 10$^{51}$ erg), and $^{56}$Ni masses (0 - 0.15 $M_{\rm \odot}$). Our analyses reveal that when the explosion energy is fixed, the light curve is primarily determined by the properties of the hydrogen-rich envelope, despite the large variation in the ZAMS masses. The dependencies of the light-curve characteristics on the envelope mass, radius, and explosion energy are investigated, and we establish the scaling relations connecting these quantities. We further derive a formula that corrects for effects of the $^{56}$Ni heating based on observables. Using the derived equations, we develop a method that can constrain the envelope mass with uncertainty within 1 $M_{\rm \odot}$ based on photometry. This method is applied to a large sample of $\sim$ 100 SNe II, which reveals a considerably broader range of the envelope masses estimated from observables as compared to those predicted by single star models evolving with standard stellar wind; this finding indicates that a large fraction of SNe II experience substantial mass-loss beyond the standard mass-loss prescription prior to their explosions, highlighting the uncertainties involved in the massive star evolution and pre-SN mass-loss mechanism.

Strong gravitational lensing is a powerful tool for investigating dark matter and dark energy properties. With the advent of large-scale sky surveys, we can discover strong lensing systems on an unprecedented scale, which requires efficient tools to extract them from billions of astronomical objects. The existing mainstream lens-finding tools are based on machine learning algorithms and applied to cut-out-centered galaxies. However, according to the design and survey strategy of optical surveys by CSST, preparing cutouts with multiple bands requires considerable efforts. To overcome these challenges, we have developed a framework based on a hierarchical visual Transformer with a sliding window technique to search for strong lensing systems within entire images. Moreover, given that multi-color images of strong lensing systems can provide insights into their physical characteristics, our framework is specifically crafted to identify strong lensing systems in images with any number of channels. As evaluated using CSST mock data based on an Semi-Analytic Model named CosmoDC2, our framework achieves precision and recall rates of 0.98 and 0.90, respectively. To evaluate the effectiveness of our method in real observations, we have applied it to a subset of images from the DESI Legacy Imaging Surveys and media images from Euclid Early Release Observations. 61 new strong lensing system candidates are discovered by our method. However, we also identified false positives arising primarily from the simplified galaxy morphology assumptions within the simulation. This underscores the practical limitations of our approach while simultaneously highlighting potential avenues for future improvements.

We address the galaxy rotation curves through the Yukawa gravitational potential emerging as a correction of the Newtonian potential in extended theories of gravity. On the one hand, we consider the contribution of the galactic bulge, galactic disk, and the dark matter halo of the Navarro-Frenk-White profile, in the framework of the standard $\Lambda$CDM model. On the other hand, we use modified Yukawa gravity to show that the rotational velocity of galaxies can be addressed successfully without the need for dark matter. In Yukawa gravity, we recover MOND and show that dark matter might be seen as an apparent effect due to the modification of the law of gravitation in terms of two parameters: the coupling constant $\alpha $ and the characteristic length $\lambda$. We thus test our theoretical scenario using the Milky Way and M31 rotation velocity curves. In particular, we place observational constraints on the free parameters of Yukawa cosmology through the Monte Carlo method and then compare our results with the predictions of the $\Lambda$CDM paradigm by making use of Bayesian information criteria. Specifically, we find that $\lambda$ is constrained to be of the order of kpc, while cosmological data suggest $\lambda$ of the order of Gpc. To explain this discrepancy, we argue that there is a fundamental limitation in measuring $\lambda$ due to the role of quantum mechanics on cosmological scales.

An inner companion has recently been discovered orbiting the prototype of classical Cepheids, delta Cep, whose orbital parameters are still not fully constrained. We collected new precise radial velocity measurements of delta Cep in 2019 using the HARPS-N spectrograph mounted at the Telescopio Nazionale Galileo. Using these radial velocity measurements, we aimed to improve the orbital parameters of the system. We considered a template available in the literature as a reference for the radial velocity curve of the pulsation of the star. We then calculated the residuals between our global dataset (composed of the new 2019 observations plus data from the literature) and the template as a function of the pulsation phase and the barycentric Julian date. This provides the orbital velocity of the Cepheid component. Using a Bayesian tool, we derived the orbital parameters of the system. Considering priors based on already published Gaia constraints, we find for the orbital period a maximum a posteriori probability of Porb=9.32+/-0.03 years (uncertainties correspond to the 95% highest density probability interval), and we obtain an eccentricity e=0.71+/-0.02, a semimajor axis a=0.029 +/-0.003 arcsecond, and a center-of-mass velocity V0=-17.28+/-0.08 km/s, among other parameters. In this short analysis we derive the orbital parameters of the delta Cep inner binary system and provide a cleaned radial velocity curve of the pulsation of the star, which will be used to study its Baade-Wesselink projection factor in a future publication.

Weakly magnetized neutron stars (WMNS) are complicated sources with challenging phenomenology. For decades, they have been studied via spectrometry and timing. It has been established that the spectrum of WMNSs consists of several components traditionally associated with the accretion disk, the boundary or spreading layer, and the wind and their interactions with each other. Since 2022, WMNSs have been actively observed with the Imaging X-ray Polarimetry Explorer (IXPE). Polarimetric studies provided new information about the behavior and geometry of these sources. One of the most enigmatic sources of the class, galactic X-ray burster GX 13+1 was first observed with IXPE in October 2023. A strongly variable polarization at the level 2-5$\%$ was detected with the source showing a rotation of the polarization angle (PA) that hinted towards the misalignment within the system. The second observation was performed in February 2024 with a complementary observation by Swift/XRT. IXPE measured an overall polarization degree (PD) of 2.5$\%$ and the PA of 24 degrees, and the Swift/XRT data helped us evaluate the galactic absorption and fit the continuum. Here we study the similarities and differences between the polarimetric properties of the source during the two observations. We confirm the expectation of the misalignment in the system and the assignment of the harder component to the boundary layer. We emphasize the importance of the wind in the system. We note the difference in the variation of polarimetric properties with energy and with time.

Atmospheric Cherenkov telescopes rely on the Earth's atmosphere as part of the detector. The presence of clouds affects observations and can introduce biases if not corrected for. Correction methods typically require an atmospheric profile, that can be measured with external atmospheric monitoring devices. We present a novel method for measuring the atmospheric profile using the data from Imaging Atmospheric Cherenkov telescopes directly. The method exploits the comparison of average longitudinal distributions of the registered Cherenkov light between clear atmosphere and cloud presence cases. Using Monte Carlo simulations of a subarray of four Large-Sized Telescopes of the upcoming Cherenkov Telescope Array Observatory and a simple cloud model we evaluate the accuracy of the method in determining the basic cloud parameters. We find that the method can reconstruct the transmission of typical clouds with an absolute accuracy of a few per cent. For low-zenith observations, the height of the cloud centre can be reconstructed with a typical accuracy of a few hundred metres, while the geometrical thickness can be accurately reconstructed only if it is >= 3 km. We also evaluate the robustness of the method against the typical systematic uncertainties affecting atmospheric Cherenkov telescopes.

The origin of intermediate helium (He)-rich hot subdwarfs are still unclear. Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf~+~main-sequence (WD+MS) channel may contribute to the intermediate He-rich hot subdwarfs. However, previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia, leading to that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs. In this work, by taking the atomic diffusion and stellar wind into account, we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code \textsc{MESA} until they evolve into hot subdwarfs. We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of $-1 \lesssim {\rm log}(N_{\rm He}/N_{\rm H}) \lesssim 0$, which are consistent with those observed in intermediate He-rich hot subdwarfs. This seems to further support that surviving companions of SNe Ia in the WD+MS channel are possible to form some intermediate He-rich hot subdwarfs.

We examine the morphological and kinematical properties of SPT-2147, a strongly lensed, massive, dusty, star-forming galaxy at $z = 3.762$. Combining data from JWST, HST, and ALMA, we study the galaxy's stellar emission, dust continuum and gas properties. The imaging reveals a central bar structure in the stars and gas embedded within an extended disc with a spiral arm-like feature. The kinematics confirm the presence of the bar and of the regularly rotating disc. Dynamical modeling yields a dynamical mass, ${M}_{\rm dyn} = (9.7 \pm 2.0) \times 10^{10}$ ${\rm M}_{\odot}$, and a maximum rotational velocity to velocity dispersion ratio, $V / \sigma = 9.8 \pm 1.2$. From multi-band imaging we infer, via SED fitting, a stellar mass, ${M}_{\star} = (6.3 \pm 0.9) \times 10^{10}$ $\rm{M}_{\odot}$, and a star formation rate, ${\rm SFR} = 781 \pm 99$ ${\rm M_{\odot} yr^{-1}}$, after correcting for magnification. Combining these measurements with the molecular gas mass, we derive a baryonic-to-total mass ratio of ${M}_{\rm bar} / {M}_{\rm dyn} = 0.9 \pm 0.2$ within 4.0 kpc. This finding suggests that the formation of bars in galaxies begins earlier in the history of the Universe than previously thought and can also occur in galaxies with elevated gas fractions.

This work presents a methodological approach to generate realistic $\gamma$-ray light curves of pulsars, resembling reasonably well the observational ones observed by the Fermi-Large Area Telescope instrument, fitting at the same time their high-energy spectra. The theoretical light curves are obtained from a spectral and geometrical model of the synchro-curvature emission. Despite our model relies on a few effective physical parameters, the synthetic light curves present the same main features observed in the observational $\gamma$-ray light curve zoo, such as the different shapes, variety in the number of peaks, and a diversity of peak widths. The morphological features of the light curves allows us to statistically compare the observed properties. In particular, we find that the proportion on the number of peaks found in our synthetic light curves is in agreement with the observational one provided by the third Fermi-LAT pulsar catalog. We also found that the detection probability due to beaming is much higher for orthogonal rotators (approaching 100%) than for small inclination angles (less than 20%).The small variation on the synthetic skymaps generated for different pulsars indicates that the geometry dominates over timing and spectral properties in shaping the gamma-ray light curves. This means that geometrical parameters like the inclination angle can be in principle constrained by gamma-ray data alone independently on the specific properties of a pulsar. At the same time, we find that $\gamma$-ray spectra seen by different observers can slightly differ, opening the door to constraining the viewing angle of a particular pulsar.

The first photometric light curve investigation of the NSVS 8294044, V1023 Her, and V1397 Her binary systems is presented. We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite (TESS) data for V1023 Her and V1397 Her. The primary and secondary times of minima were extracted from all the data, and by collecting the literature, a new ephemeris was computed for each system. Linear fits for the O-C diagrams were conducted using the Markov chain Monte Carlo (MCMC) method. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs (PHOEBE) Python code and the MCMC approach. The systems were found to be contact binary stars based on the fillout factor and mass ratio. V1023 Her showed the O'Connell effect, and a cold starspot on the secondary component was required for the light curve solution. The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass. We presented a new T-M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit. The positions of the systems were also depicted on the M-L, M-R, q-L_{ratio}, and M_{tot}-J_0 diagrams in the logarithmic scales.

The radius valley separating super-Earths from mini-Neptunes is a fundamental benchmark for theories of planet formation and evolution. Observations show that the location of the radius valley decreases with decreasing stellar mass and with increasing orbital period. Here, we build from our previous pebble-based formation model, which, combined with photoevaporation after disc dispersal, unveiled the radius valley as a separator between rocky- and water-worlds. We expand our models for a range of stellar masses spanning from 0.1 to 1.5 $M_\odot$. We find that the location of the radius valley is well described by a power-law in stellar mass as $R_{\rm valley} = 1.8197 \, M_{\star}^{\!0.14({+0.02}/{-0.01})}$, which is in excellent agreement with observations. We also find very good agreement with the dependence of the radius valley on orbital period, both for FGK- and M-dwarfs. Additionally, we note that the radius valley gets filled towards low stellar masses, particularly at 0.1-0.4 $M_\odot$, yielding a rather flat slope in $R_{\rm valley} - P_{\rm orb}$. This is the result of orbital migration occurring at lower planet mass for less massive stars, which allows for low-mass water-worlds to reach the inner regions of the system, blurring the separation in mass (and size) between rocky- and water-worlds. Furthermore, we find that for planetary equilibrium temperatures above 400 K, the water in the volatile layer exists fully in the form of steam, puffing the planet radius up compared to condensed-water worlds. This produces an increase in planet radii of $\sim 30\%$ at 1 $M_\oplus$, and of $\sim 15\%$ at 5 $M_\oplus$, compared to condensed-water-worlds. As with Sun-like stars, pebble accretion leaves its imprint on the overall exoplanet population as a depletion of planets with intermediate compositions, carving a valley in planet density for all spectral types (abridged).

On March 6 2023, the Gaia telescope has alerted a 2-magnitude burst from Gaia23bab, a Young Stellar Object in the Galactic plane. We observed Gaia23bab with the Large Binocular Telescope obtaining optical and near-infrared spectra close in time to the peak of the burst, and collected all public multi-band photometry to reconstruct the historical light curve. This latter shows three bursts in ten years (2013, 2017 and 2023), whose duration and amplitude are typical of EXor variables. We estimate that, due to the bursts, the mass accumulated on the star is about twice greater than if the source had remained quiescent for the same period of time. Photometric analysis indicates that Gaia23bab is a Class,II source with age < 1 Myr, spectral type G3-K0, stellar luminosity 4.0 L_sun, and mass 1.6 M_sun. The optical/near infrared spectrum is rich in emission lines. From the analysis of these lines we measured the accretion luminosity and the mass accretion rate L_acc(burst)=3.7 L_sun, M_acc(burst) 2.0 10 $^(-7) M_sun/yr, consistent with those of EXors. More generally, we derive the relationships between accretion and stellar parameters in a sample of EXors. We find that, when in burst, the accretion parameters become almost independent of the stellar parameters and that EXors, even in quiescence, are more efficient than classical T Tauri stars in assembling mass.

Thanks to the recent advancement in producing rare isotopes and measuring their masses with unprecedented precision, the updated nuclear masses around the waiting-point nucleus $^{64}$Ge in the rapid-proton capture process have led to a significant revision of the surface gravitational redshift of the neutron star (NS) in GS 1826-24 by re-fitting its X-ray burst light curve ({\it X. Zhou et al., Nature Physics {\bf 19}, 1091 (2023)}) using Modules for Experiments in Stellar Astrophysics (MESA). The resulting NS compactness $\xi$ is between 0.244 and 0.342 at 95\% confidence level and its upper boundary is significantly smaller than the maximum $\xi$ previously known. Incorporating this new data within a comprehensive Bayesian statistical framework, we investigate its impact on the Equation of State (EOS) of supradense neutron-rich matter and the required spin frequency for GW190814's minor $m_2$ with mass $2.59\pm 0.05$M$_{\odot}$ to be a rotationally stable pulsar. We found that the EOS of high-density symmetric nuclear matter (SNM) has to be softened significantly while the symmetry energy at supersaturation densities stiffened compared to our prior knowledge from earlier analyses using data from both astrophysical observations and terrestrial nuclear experiments. In particular, the skewness $J_0$ characterizing the stiffness of high-density SNM decreases significantly, while the slope $L$, curvature $K_{\rm{sym}}$, and skewness $J_{\rm{sym}}$ of nuclear symmetry energy all increase appreciably compared to their fiducial values. We also found that the most probable spin rate for the $m_2$ to be a stable pulsar is very close to its mass-shedding limit once the revised redshift data from GS 1826-24 is considered, making the $m_2$ unlikely the most massive NS observed so far.

We investigate the East-West asymmetry in energetic storm particle (ESP) heavy ion intensities at interplanetary shocks driven by coronal mass ejections (CMEs) during solar cycles (SCs) 23 and 24. We use observations from NASA's ACE and STEREO missions of helium (He), oxygen (O), and iron (Fe) intensities from ~0.13 to 3 MeV/nucleon. We examine the longitudinal distribution of ESP intensities and the correlation of ESP intensities with the near-Sun CME speed and the average transit CME speed for eastern and western events. We observed an East-West asymmetry reversal of ESP heavy ion intensities from SC 23 to 24. We have determined that this change in asymmetry is caused by a shift in the heliolongitude distribution of the CME speed ratio (the ratio of CME near-Sun speed to CME average transit speed) from west to east.

Based on the DESI Legacy Imaging Surveys released data and available spectroscopic redshifts, we identify 1.58 million clusters of galaxies by searching for the overdensity of stellar mass distribution of galaxies within redshift slices around pre-selected massive galaxies, among which 877,806 clusters are found for the first time. The identified clusters have an equivalent mass of M_{500}> 0.47*10^{14}~Msolar with an uncertainty of 0.2 dex. The redshift distribution of clusters extends to z~1.5, and 338,841 clusters have spectroscopic redshifts. Our cluster sample includes most of the rich optical clusters in previous catalogs, more than 95% massive Sunyaev-Zeldovich clusters and 90% ROSAT and eROSITA X-ray clusters. From the light distributions of member galaxies, we derive the dynamical state parameters for 28,038 rich clusters and find no significant evolution of the dynamical state with redshift. We find that the stellar mass of the brightest cluster galaxies grows by a factor of 2 since z=1.

We explore the survival of a galaxy's circumgalactic medium (CGM) as it experiences ram pressure stripping (RPS) moving through the intracluster medium (ICM). For a satellite galaxy, the CGM is often assumed to be entirely stripped/evaporated, an assumption that may not always be justified. We carry out 3D-hydrodynamics simulations of RPS of the interstellar medium (ISM) and the CGM of a galaxy with mass and size comparable to the jellyfish galaxy JO201. We find that the CGM can survive long at cluster outskirts ($\gtrsim 2$ Gyr). However, at smaller cluster-centric distances, 90\% of the CGM mass is lost within $\sim 500$ Myr. Our simulations suggest that the gravitational restoring force on the CGM is mostly negligible and the CGM-ICM interaction is analogous to 'cloud-wind interaction'. The CGM stripping timescale depends not on the ram pressure but on $\chi$, the ratio of CGM to ICM density. Two distinct regimes emerge for CGM stripping: the $\chi >1$ regime, which is the well-known 'cloud-crushing' problem, and the $\chi < 1$ regime, which we refer to as the (relatively unexplored) 'bubble-drag' problem. The cloud-crushing regime ($\chi >1$) suggests a CGM stripping timescale proportional to the drag time $t_{\rm drag} \sim \chi R/v_{\rm rel}$ ($R$ is the CGM size, $v_{\rm rel}$ is the relative velocity). The bubble-drag regime ($\chi < 1$) is qualitatively different and gives a shorter stripping timescale comparable to the crossing time -- $t_{\rm drag} \sim R/v_{\rm rel}$, independent of $\chi$. The ISM stripping criterion unlike the CGM, still depends on the ram pressure $\rho_{\rm ICM} v_{\rm rel}^2$ (the classic Gunn and Gott 1972 condition). The stripped tails of satellites contain contributions from both the disk and its trailing CGM. Overall, we identify novel physical mechanisms and previously unexplored stripping regimes.

The magnetic fields in our Milky Way can be revealed by the distribution of Faraday rotation measures (RMs) of radio sources behind the Galaxy and of radio pulsars inside the Galaxy. Based on the antisymmetry of the Faraday sky in the inner Galaxy to the Galactic coordinates, the magnetic field toroids above and below the Galactic plane with reversed field directions exist in the Galactic halo and have been included in almost all models for the global magnetic structure in the Milky Way. However, the quantitative parameters, such as the field strength, the scale height, and the scale radius of the toroids are hard to determine from observational data. It has long been argued that the RM antisymmetry could be dominated by the local contributions of the interstellar medium. Here we discount the local RM contributions measured by pulsars mostly located within 5 kpc and get the first quantitative estimate of the size of magnetic toroids in the Galactic halo. They are huge, starting from a Galactocentric radius of less than 2 kpc to at least 15 kpc without field direction reversals. Such magnetic toroids in the Galactic halo should naturally constrain the physical processes in galaxies.

Inferences of the magnetic field in the solar atmosphere by means of spectropolarimetric inversions (i.e., Stokes inversion codes) yield magnetic fields that are non-solenoidal($\nabla\cdot{\bf B} \ne 0$). Because of this, results obtained by such methods are sometimes put into question. We aim to develop and implement a new technique that can retrieve magnetic fields that are simultaneously consistent with observed polarization signals and with the null divergence condition. The method used in this work strictly imposes $\nabla\cdot{\bf B}=0$ by determining the vertical component of the magnetic field ($B_{\rm z}$) from the horizontal ones ($B_{\rm x},B_{\rm y}$). We implement this solenoidal inversion into the FIRTEZ Stokes inversion code and apply it to spectropolarimetric observations of a sunspot observed with the Hinode/SP instrument. We show that the solenoidal inversion retrieves a vertical component of the magnetic field that is consistent with the vertical component of the magnetic field inferred from the non-solenoidal one. We demonstrate that the solenoidal inversion is capable of a better overall fitting to the observed Stokes vector than the non-solenoidal inversion. In fact, the solenoidal magnetic field fits Stokes $V$ worse, but this is compensated by a better fit to Stokes $I$. We find a direct correlation between the worsening in the fit to the circular polarization profiles by the solenoidal inversion and the deviations in the inferred $B_{\rm z}$ with respect to the non-solenoidal inversion. These results support the idea that common Stokes inversion techniques fail to reproduce $\nabla\cdot{\bf B}=0$ mainly as a consequence of the uncertainties in the determination of the individual components of the magnetic field.

We report here on the timing of 597 pulsars over the last four years with the MeerKAT telescope. We provide Times-of-Arrival, pulsar ephemeris files and per-epoch measurements of the flux density, dispersion measure (DM) and rotation measure (RM) for each pulsar. In addition we use a Gaussian process to model the timing residuals to measure the spin frequency derivative at each epoch. We also report the detection of 11 glitches in 9 individual pulsars. We find significant DM and RM variations in 87 and 76 pulsars respectively. We find that the DM variations scale approximately linearly with DM, which is broadly in agreement with models of the ionised interstellar medium. The observed RM variations seem largely independent of DM, which may suggest that the RM variations are dominated by variations in the interstellar magnetic field on the line of sight, rather than varying electron density. We also find that normal pulsars have around 5 times greater amplitude of DM variability compared to millisecond pulsars, and surmise that this is due to the known difference in their velocity distributions.

We describe an X-ray source detection method entirely based on the maximum likelihood analysis, in application to observations with the ART-XC telescope onboard the Spectrum Roentgen Gamma observatory. The method optimally combines the data taken at different conditions, a situation commonly found in scanning surveys or mosaic observations with a telescope with a significant off-axis PSF distortion. The method can be naturally extended to include additional information from the X-ray photon energies, detector grades, etc. The likelihood-based source detection naturally results in a stable and uniform definition of detection thresholds under different observing conditions (PSF, background level). This greatly simplifies the statistical calibration of the survey needed to, e.g., obtain the $\log N - \log S$ distribution of detected sources or their luminosity function. The method can be applied to the data from any imaging X-ray telescope.

The ASTRI Mini-Array project, led by the Italian National Institute for Astrophysics, aims to construct and operate nine Imaging Atmospheric Cherenkov Telescopes for high-energy gamma-ray source study and stellar intensity interferometry. Located at the Teide Astronomical Observatory in Tenerife, the project's software is essential for remote operation, emphasizing the need for prompt feedback on observations. This contribution introduces the Online Observation Quality System (OOQS) as part of the Supervisory Control And Data Acquisition (SCADA) software. OOQS performs real-time data quality checks on data from Cherenkov cameras and Intensity Interferometry instruments. It provides feedback to SCADA and operators, highlighting abnormal conditions and ensuring quick corrective actions for optimal observations. Results are archived for operator visualization and further analysis. The OOQS data quality pipeline prototype utilizes a distributed application with three main components to handle the maximum array data rate of 1.15 Gb/s. The first is a Kafka consumer that manages the data stream from the Array Data Acquisition System through Apache Kafka, handling the data serialization and deserialization involved in the transmission. The data stream is divided into batches of data written in files. The second component monitors new files and conducts analyses using the Slurm workload scheduler, leveraging its parallel processing capabilities and scalability. Finally, the process results are collected by the last component and stored in the Quality Archive.

Star-forming galaxies can reach quiescence via rapid transition through merger-triggered starbursts that consequently affect both their kinematics and star formation rates. In this work, we analyze the spatially-resolved kinematics of 92 post-starburst galaxies (PSBs) with data from the MaNGA survey and place them in context with early-type galaxies (ETGs) to study the impact of merger history on galaxy kinematics. We measure the specific angular momentum to characterize them as slow or fast rotators. We find that the MaNGA PSB sample has $5\%$ slow rotators, which is less than the $14\%$ slow rotators in the ATLAS$^{3D}$ ETG sample and $22\%$ slow rotators in the MaNGA ETGs. The PSBs have lower specific angular momentum than the star-forming galaxies (SFs) and a greater fraction of slow rotators. This implies that for the PSBs to evolve into the ETGs, they must still lose some angular momentum. While ETGs with higher stellar mass tend to be slow rotators, PSBs do not follow this trend. We find significant correlations between specific angular momentum and mass-weighted age for the SF and ETG samples, but do not see any significant trends within the short PSB phase. These results indicate that significant evolution in angular momentum must continue to take place as the galaxy ages after the PSB phase. For PSBs to evolve directly into ETGs, they must undergo dry mergers to shed excess angular momentum without causing further epochs of star formation.

We present results of a dual eclipse expedition to observe the solar corona from two sites during the annular solar eclipse of 2023 October 14, using a novel coronagraph designed to be accessible for amateurs and students to build and deploy. The coronagraph "CATEcor" builds on the standardized eclipse observing equipment developed for the Citizen CATE 2024 experiment. The observing sites were selected for likelihood of clear observations, for historic relevance (near the Climax site in the Colorado Rocky Mountains), and for centrality to the annular eclipse path (atop Sandia Peak above Albuquerque, New Mexico). The novel portion of CATEcor is an external occulter assembly that slips over the front of a conventional dioptric telescope, forming a "shaded-truss" externally occulted coronagraph. CATEcor is specifically designed to be easily constructed in a garage or "makerspace" environment. We successfully observed some bright features in the solar corona to an altitude of approximately 2.25 R$_\odot$ during the annular phases of the eclipse. Future improvements to the design, in progress now, will reduce both stray light and image artifacts; our objective is to develop a design that can be operated successfully by amateur astronomers at sufficient altitude even without the darkened skies of a partial or annular eclipse.

AGILE is an Italian Space Agency (ASI) space mission launched in 2007 to study X-ray and gamma-ray phenomena in the energy range from $\sim$20 keV to $\sim$10 GeV. The AGILE AntiCoincidence System (ACS) detects hard-X photons in the 50 - 200 keV energy range and continuously stores each panel's count rates in the telemetry. We developed a new Deep Learning (DL) model to predict the background of the AGILE ACS top panel using the satellite's orbital and attitude parameters. This model aims to learn how the orbital and spinning modulations of the satellite impact the background level of the ACS top panel. The DL model executes a regression problem, and is trained with a supervised learning technique on a dataset larger than twenty million orbital parameters' configurations. Using a test dataset, we evaluated the trained model by comparison of the predicted count rates with the real ones. The results show that the model can reconstruct the background count rates of the ACS top panel with an accuracy of 96.7\%, considering the orbital modulation and spinning of the satellite. Starting from these promising results, we are developing an anomaly detection method to detect Gamma-ray Bursts when the differences between predicted and real count rates exceed a predefined threshold.

We present a comprehensive reassessment of the state of Interacting Dark Energy (IDE) cosmology, namely models featuring a non-gravitational interaction between Dark Matter (DM) and Dark Energy (DE). To achieve high generality, we extend the dark sector physics by considering two different scenarios: a non-dynamical DE equation of state $w_0\neq-1$, and a dynamical $w(a)=w_0+w_a(1-a)$. In both cases, we distinguish two different physical regimes resulting from a phantom or quintessence equation of state. To circumvent early-time superhorizon instabilities, the energy-momentum transfer should occur in opposing directions within the two regimes, resulting in distinct phenomenological outcomes. We study quintessence and phantom non-dynamical and dynamical models in light of two independent Cosmic Microwave Background (CMB) experiments - the Planck satellite and the Atacama Cosmology Telescope. We analyze CMB data both independently and in combination with Supernovae (SN) distance moduli measurements from the Pantheon-Plus catalog and Baryon Acoustic Oscillations (BAO) from the SDSS-IV eBOSS survey. Our results update and extend the state-of-the-art analyses, significantly narrowing the parameter space allowed for these models and limiting their overall ability to reconcile cosmological tensions. Although considering different combinations of data leaves some freedom to increase $H_0$ towards the value measured by the SH0ES collaboration, our most constraining dataset (CMB+BAO+SN) indicates that fully reconciling the tension solely within the framework of IDE remains challenging.

We study the kinematics of a pillar, namely G287.76-0.87, using three rotational lines of $^{12}$CO(5-4), $^{12}$CO(8-7), $^{12}$CO(11-10), and a fine structure line of [OI] $63\,\mu$m Southern Carina observed by SOFIA/GREAT. This pillar is irradiated by the associated massive star cluster Trumpler 16, which includes $\eta$~Carina. Our analysis shows that the relative velocity of the pillar with respect to this ionization source is small, $\sim 1\,\rm km\,s^{-1}$, and the gas motion in the tail is more turbulent than in the head. We also performed analytical calculations to estimate the gas column density in local thermal equilibrium (LTE) conditions, which yields $N_{\rm CO}$ as $(\sim 0.2 -5)\times 10^{17}\,\rm cm^{-2}$. We further constrain the gas's physical properties in non-LTE conditions using RADEX. The non-LTE estimations result in $n_{\rm H_{2}} \simeq 10^{5}\,\rm cm^{-3}$ and $N_{\rm CO} \simeq 10^{16}\,\rm cm^{-2}$. We found that the thermal pressure within the G287.76-0.87 pillar is sufficiently high to make it stable for the surrounding hot gas and radiation feedback if the winds are not active. While they are active, stellar winds from the clustered stars sculpt the surrounding molecular cloud into pillars within the giant bubble around $\eta$~Carina.

We present an approach to detecting (linear) gravitational wave memory in a Galactic core-collapse supernova using current interferometers. Gravitational wave memory is an important prediction of general relativity that has yet to be confirmed. Our approach uses a combination of Linear Prediction Filtering and Matched-Filtering. We present the results of our approach on data from core-collapse supernova simulations that span a range of progenitor mass and metallicity. We are able to detect gravitational wave memory out to 10 kpc. We also present the False Alarm Probabilities assuming an On-Source Window compatible with the presence of a neutrino detection.

A bright ($m_{\rm F150W,AB}$=24 mag), $z=1.95$ supernova (SN) candidate was discovered in JWST/NIRCam imaging acquired on 2023 November 17. The SN is quintuply-imaged as a result of strong gravitational lensing by a foreground galaxy cluster, detected in three locations, and remarkably is the second lensed SN found in the same host galaxy. The previous lensed SN was called "Requiem", and therefore the new SN is named "Encore". This makes the MACS J0138.0$-$2155 cluster the first known system to produce more than one multiply-imaged SN. Moreover, both SN Requiem and SN Encore are Type Ia SNe (SNe Ia), making this the most distant case of a galaxy hosting two SNe Ia. Using parametric host fitting, we determine the probability of detecting two SNe Ia in this host galaxy over a $\sim10$ year window to be $\approx3\%$. These observations have the potential to yield a Hubble Constant ($H_0$) measurement with $\sim10\%$ precision, only the third lensed SN capable of such a result, using the three visible images of the SN. Both SN Requiem and SN Encore have a fourth image that is expected to appear within a few years of $\sim2030$, providing unprecedented baseline for time-delay cosmography.

Most brown dwarfs show some level of photometric or spectral variability. However, finding the most variable dwarfs more suited for a thorough variability monitoring campaign remained a challenge until a few years ago with the design of spectral indices to find the most likely L and T dwarfs using their near-infrared single-epoch spectrum. In this work, we designed and tested near-infrared spectral indices to pre-select the most likely variable L4-L8 dwarfs, complementing the indices presented by Ashraf et al. (2022) and Oliveros-Gomez et al. (2022). We used time-resolved near-infrared Hubble Space Telescope Wide Field Camera 3 spectra of an L6.0 dwarf, LP 261-75b, to design our novel spectral indices. We tested these spectral indices on 75 L4.0-L8.0 near-infrared SpeX/IRTF spectra, providing 27 new variable candidates. Our indices have a recovery rate of 80 percent and a false negative rate of 25 percent. All the known non-variable brown dwarfs were found to be non-variable by our indices. We estimated the variability fraction of our sample to be near 51 percent, which agrees with the variability fractions provided by Buenzli et al. (2014), Radigan et al. (2014), and Metchev et al. (2015) for L4-L8 dwarfs. These spectral indices may support in the future, the selection of the most likely variable directly-imaged exoplanets for studies with the James Webb Space Telescope and as well as the 30-m telescopes.

The detection of narrow channels of accretion toward protostellar disks, known as streamers, have increased in number in the last few years. However, it is unclear if streamers are a common feature around protostars that were previously missed, or if they are a rare phenomenon. Our goals are to obtain the incidence of streamers toward a region of clustered star formation and to trace the origins of their gas, to determine if they originate within the filamentary structure of molecular clouds or from beyond. We used combined observations of the nearby NGC 1333 star-forming region, carried out with the NOEMA interferometer and the IRAM 30m single dish. Our observations cover the area between the IRAS 4 and SVS 13 systems. We traced the chemically fresh gas within NGC 1333 with HC3N molecular gas emission and the structure of the fibers in this region with N2H+ emission. We fit multiple velocity components in both maps and used clustering algorithms to recover velocity-coherent structures. We find streamer candidates toward 7 out of 16 young stellar objects within our field of view. This represents an incidence of approximately 40\% of young stellar objects with streamer candidates when looking at a clustered star forming region. The incidence increases to about 60\% when we considered only embedded protostars. All streamers are found in HC3N emission. Given the different velocities between HC3N and N2H+ emission, and the fact that, by construction, N2H+ traces the fiber structure, we suggest that the gas that forms the streamers comes from outside the fibers. This implies that streamers can connect cloud material that falls to the filaments with protostellar disk scales.

We measure the stacked lensing signal in the direction of galaxy clusters in the Dark Energy Survey Year 3 (DES Y3) redMaPPer sample, using cosmic microwave background (CMB) temperature data from SPT-3G, the third-generation CMB camera on the South Pole Telescope (SPT). We estimate the lensing signal using temperature maps constructed from the initial 2 years of data from the SPT-3G 'Main' survey, covering 1500 deg$^2$ of the Southern sky. We then use this signal as a proxy for the mean cluster mass of the DES sample. In this work, we employ three versions of the redMaPPer catalogue: a Flux-Limited sample containing 8865 clusters, a Volume-Limited sample with 5391 clusters, and a Volume&Redshift-Limited sample with 4450 clusters. For the three samples, we find the mean cluster masses to be ${M}_{200{\rm{m}}}=1.66\pm0.13$ [stat.]$\pm0.03$ [sys.], $1.97\pm0.18$ [stat.]$\pm0.05$ [sys.], and $2.11\pm0.20$ [stat.]$\pm0.05$ [sys.]$\times{10}^{14}\ {\rm{M}}_{\odot }$, respectively. This is a factor of $\sim2$ improvement relative to the precision of measurements with previous generations of SPT surveys and the most constraining cluster mass measurements using CMB cluster lensing to date. Overall, we find no significant tensions between our results and masses given by redMaPPer mass-richness scaling relations of previous works, which were calibrated using CMB cluster lensing, optical weak lensing, and velocity dispersion measurements from various combinations of DES, SDSS and Planck data. We then divide our sample into 3 redshift and 3 richness bins, finding no significant tensions with optical weak-lensing calibrated masses in these bins. We forecast a $5.8\%$ constraint on the mean cluster mass of the DES Y3 sample with the complete SPT-3G surveys when using both temperature and polarization data and including an additional $\sim1400$ deg$^2$ of observations from the 'Extended' SPT-3G survey.

We show that quantum fluctuations of an expanding phase transition bubble give rise to gravitational wave (GW) emission, even when considering a single bubble, without bubble collisions or plasma effects. The ratio of GW energy to the total bubble energy reservoir increases with time as $\propto t$. If the bubble expands for long enough before percolation destroys it, back-reaction due to the GW emission becomes important after $t_{\rm br}\sim (16\pi^5) m_{\rm pl}^2R_0^3$, where $R_0$ is the bubble nucleation radius and $m_{\rm pl}$ is the reduced Planck mass. As seen by experiments today, the GW energy spectrum would appear blue. However, simple estimates suggest that the signal falls short of detection by even ambitious future experiments.

We show that there is a fundamental flaw in the application of modified gravity theories in cosmology, taking $f(R)$ gravity as a paradigmatic example. This theory contains a scalar degree of freedom that couples to the matter stress-energy tensor but not to gravitational energy. However, when applied to cosmology this theory is unable to distinguish between gravitational and non-gravitational energy. Hence the cosmological version of the theory does not coincide with its own macroscopic average, and we show that this leads to order-one discrepancies. We argue that the same inconsistency is common to many other modified gravity theories with extra degrees of freedom. Our results put into question whether these theories can make sense as the cosmological average of a fundamental theory, hence challenging their physical significance.

There is a large and growing interest in observations of small-scale structure in dark matter. We propose a new way to probe dark matter structures in the $\sim 10 - 10^8 \, M_\odot$ range. This allows us to constrain the primordial power spectrum over shorter distances scales than possible with direct observations from the CMB. For $k$ in the range $\sim 10 - 1000 \, {\rm Mpc}^{-1}$ our constraints on the power spectrum are orders of magnitude stronger than previous bounds. We also set some of the strongest constraints on dark matter isocurvature perturbations. Our method relies on the heating effect such dark matter substructures would have on the distribution of stars in an ultra-faint dwarf galaxy. Many models of inflation produce enhanced power at these short distance scales and can thus be constrained by our observation. Further, many dark matter models such as axion dark matter, self-interacting dark matter and dissipative dark matter, produce dense structures which could be constrained this way.

We present several high-accuracy surrogate models for gravitational-wave signals from equal-mass head-on mergers of Proca stars, computed through the Newman-Penrose scalar $\psi_4$. We also discuss the current state of the model extensions to mergers of Proca stars with different masses, and the particular challenges that these present. The models are divided in two main categories: two-stage and monolithic. In the two-stage models, a dimensional reduction algorithm is applied to embed the data in a reduced feature space, which is then interpolated in terms of the physical parameters. For the monolithic models, a single neural network is trained to predict the waveform from the input physical parameter. Our model displays mismatches below $10^{-3}$ with respect to the original numerical waveforms. Finally, we demonstrate the usage of our model in full Bayesian parameter inference through the accurate recovery of numerical relativity signals injected in zero-noise, together with the analysis of GW190521. For the latter, we observe excellent agreement with existing results that make use of full numerical relativity.

Ultralight particles are theoretically well-motivated dark matter candidates. In the vicinity of the solar system, these ultralight particles are described as a superposition of plane waves, resulting in a stochastic field with amplitude fluctuations on scales determined by the velocity dispersion of dark matter. In this work, we systematically investigate the sensitivity of space-based gravitational-wave interferometers to the stochastic ultralight dark matter field within the frequentist framework. We derive the projected sensitivity of a single detector using the time-delay interferometry and find that the stochastic effect will only diminish the performance of the detector marginally, unlike searches in other contexts where significant reductions are found. Furthermore, we explore the sensitivity of detector network in two typical configurations. We find that the well-separated configuration, where the distance between two detectors exceeds the coherence length of dark matter, is the optimal choice for ultralight dark matter detection due to a less chance of missing signal. This contrasts with the detection of stochastic gravitational-wave background, where the co-located and co-aligned configuration is preferred. Our results may provide useful insights for potential joint observations involving gravitational-wave detectors like LISA, Taiji and TianQin.

The back-linked Fabry-Perot interferometer (BLFPI) is an interferometer topology proposed for space gravitational wave antennas with the use of inter-satellite Fabry-Perot interferometers. The BLFPI offers simultaneous and independent control over all interferometer length degrees of freedom by controlling the laser frequencies. Therefore, BLFPI does not require an active control system for the physical lengths of the inter-satellite Fabry-Perot interferometers. To achieve a high sensitivity, the implementation must rely on an offline signal process for subtracting laser frequency noises. However, the subtraction has not been experimentally verified to date. This paper reports a demonstration of the frequency noise subtraction in the frequency band of 100 Hz-50 kHz, including the cavity pole frequency, using Fabry-Perot cavities with a length of 46 cm. The highest reduction ratio of approximately 200 was achieved. This marks the first experimental verification of the critical function in the BLFPI.

Nucleation rate computations are of broad importance in particle physics and cosmology. Perturbative calculations are often used to compute the nucleation rate $\Gamma$, but these are incomplete. We perform nonperturbative lattice simulations of nucleation in a scalar field theory with a tree-level barrier, computing a final result extrapolated to the thermodynamic and continuum limits. Although the system in question should be well-described by a complete one-loop perturbative calculation, we find only qualitative agreement with the full perturbative result, with a 20% discrepancy in $|\log \Gamma|$. Our result motivates further testing of the current nucleation paradigm.

Motivated by the excess of the muon content of cosmic ray induced extensive air showers (EAS), relative to EAS modeling, observed by the Pierre Auger Observatory, and by the tension between Auger data and air shower simulations on the maximal muon production depth $X^{\mu}_{\max}$, we investigate the possibility to modify the corresponding EAS simulation results, within the Standard Model of particle physics. We start by specifying the kinematic range for secondary hadron production, which is of relevance for such predictions. We further investigate the impact on the predicted EAS muon number and on $X^{\mu}_{\max}$ of various modifications of the treatment of hadronic interactions, in the framework of the QGSJET-III model, in particular the model calibration to accelerator data, the amount of the "glue" in the pion, and the energy dependence of the pion exchange process. None of the considered modifications of the model allowed us to enhance the EAS muon content by more than 10\%. On the other hand, for the maximal muon production depth, some of the studied modifications of particle production give rise up to $\sim 10$ g/cm$^2$ larger $X^{\mu}_{\max}$ values, which increases the difference with Auger observations.

Tetrahedral configurations of spacecraft on unperturbed heliocentric orbits allow for highly precise observations of small spatial changes in the gravitational field, especially those affecting the gravity gradient tensor (GGT). The resulting high sensitivity may be used to search for new physics that could manifest itself via deviations from general relativistic behavior yielding a non-vanishing trace[GGT]. We study the feasibility of recovering the trace[GGT] with the sensitivity of O(1e-24 s^(-2)) -- the level where some of the recently proposed cosmological models may have observable effects in the solar system. We consider how local measurements provided by precision laser ranging and atom-wave interferometry can be used for that purpose. We report on a preliminary study of such an experiment and precision that may be reached in measuring the trace[GGT], with the assumption of drag-compensated spacecraft by atom interferometer measurements. For that, we study the dynamical behavior of a tetrahedral formation established by four spacecraft on heliocentric nearby elliptical orbits. We formulate the observational equations to measure the trace[GGT] relying only on the observables available within the formation: laser ranging and the Sagnac interferometry. We demonstrate that Sagnac observable is a mission enabling and allows to measure the angular frequency of the tetrahedral rotation with respect to an inertial reference frame with an accuracy much higher than that available from any other modern navigational techniques. We show that the quality of the science measurements is affected by the changes in tetrahedron's orientation and shape as spacecraft follow their orbits. We present the preliminary mission and instrument requirements needed to measure the trace[GGT] to the required accuracy and demonstrate the feasibility of satisfying the science objectives.

I propose an observationally and theoretically consistent resolution of the cosmological constant problem: $\Lambda$ is a counterterm - with a running coupling - that balances the monopole celestial sky average of the kinetic energy of expansion of inhomogeneously distributed `small' cosmic voids. No other dark energy source is required. This solution relies on the first investigation of void statistics in cosmological simulations in full general relativity (arXiv:2403.15134). Results are consistent with parameters of the Timescape model of cosmological backreaction. Crucially, dynamical spatial curvature arises as time-varying spatial gradients of the kinetic spatial curvature, and depends directly on the void volume fraction. Its monopole average generates the cosmological term. This result potentially resolves the Hubble tension and offers new approaches to tackling other tensions and anomalies.