Papers for Wednesday, Nov 08 2023

Recently, pulsar timing array (PTA) collaborations, including NANOGrav, have reported evidence of a stochastic gravitational wave background within the nHz frequency range.\ It can be interpreted by gravitational waves from preheating era. In this context, we demonstrate that the emission of this stochastic gravitational wave background can be attributed to fluctuations occurring at the end of inflation, thus giving rise to the Hubble tension issue. At the onset of inflation, the value of the frequency of the gravitational wave signal stood at $f=0.08nHz$, but it rapidly transitioned to $f=1nHz$ precisely at the end of inflation. However, just before the end of inflation, a phase characterized by curvature perturbation is known to occur, causing a swift increase in the frequency.

The ANAIS experiment is intended to search for dark matter annual modulation with ultrapure NaI(Tl) scintillators in order to provide a model independent confirmation or refutation of the long-standing DAMA/LIBRA positive annual modulation signal in the low energy detection rate, using the same target and technique. Other experiments exclude the region of parameters singled out by DAMA/LIBRA. However, these experiments use different target materials, so the comparison of their results depends on the models assumed for the dark matter particle and its distribution in the galactic halo. ANAIS-112, consisting of nine 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc., disposed in a 3$\times$3 matrix configuration, is taking data smoothly with excellent performance at the Canfranc Underground Laboratory, Spain, since August, 2017. Last published results corresponding to three-year exposure were compatible with the absence of modulation and incompatible with DAMA/LIBRA for a sensitivity above 2.5$\sigma$ C.L. Present status of the experiment and a reanalysis of the first 3 years data using new filtering protocols based on machine-learning techniques are reported. This reanalysis allows to improve the sensitivity previously achieved for the DAMA/LIBRA signal. Updated sensitivity prospects are also presented: with the improved filtering, testing the DAMA/LIBRA signal at 5$\sigma$ will be within reach in 2025.

When two galaxies merge, they often produce a supermassive black hole binary (SMBHB) at their center. Numerical simulations with cold dark matter show that SMBHBs typically stall out at a distance of a few parsecs apart, and take billions of years to coalesce. This is known as the final parsec problem. We suggest that ultralight dark matter (ULDM) halos around SMBHBs can generate dark matter waves due to gravitational cooling. These waves can effectively carry away orbital energy from the black holes, rapidly driving them together. To test this hypothesis, we performed numerical simulations of black hole binaries inside ULDM halos. Our results imply that ULDM waves can lead to the rapid orbital decay of black hole binaries.

This document describes BinCodex, a common format for the output of binary population synthesis (BPS) codes agreed upon by the members of the LISA Synthetic UCB Catalogue Group. The goal of the format is to provide a common reference framework to describe the evolution of a single, isolated binary system or a population of isolated binaries.

Chain inflation is an alternative to slow-roll inflation in which the inflaton tunnels along a large number of consecutive minima in its potential. In this work we perform the first comprehensive calculation of the gravitational wave spectrum of chain inflation. In contrast to slow-roll inflation the latter does not stem from quantum fluctuations of the gravitational field during inflation, but rather from the bubble collisions during the first-order phase transitions associated with vacuum tunneling. Our calculation is performed within an effective theory of chain inflation which builds on an expansion of the tunneling rate capturing most of the available model space. The effective theory can be seen as chain inflation's analogue of the slow-roll expansion in rolling models of inflation. We show that chain inflation produces a very characteristic double-peak spectrum: a faint high-frequency peak associated with the gravitational radiation emitted during inflation, and a strong low-frequency peak associated with the graceful exit from chain inflation (marking the transition to the radiation-dominated epoch). There exist very exciting prospects to test the gravitational wave signal from chain inflation at the aLIGO-aVIRGO-KAGRA network, at LISA and /or at pulsar timing array experiments. A particularly intriguing possibility we point out is that chain inflation could be the source of the stochastic gravitational wave background recently detected by NANOGrav, PPTA, EPTA and CPTA. We also show that the gravitational wave signal of chain inflation is often accompanied by running/ higher running of the scalar spectral index to be tested at future Cosmic Microwave Background experiments.

We test Milgromian dynamics (MOND) using wide binary stars (WBs) with separations of $2-30$ kAU. Locally, the WB orbital velocity in MOND should exceed the Newtonian prediction by $\approx 20\%$ at asymptotically large separations given the Galactic external field effect (EFE). We investigate this with a detailed statistical analysis of \emph{Gaia} DR3 data on 8611 WBs within 250 pc of the Sun. Orbits are integrated in a rigorously calculated gravitational field that directly includes the EFE. We also allow line of sight contamination and undetected close binary companions to the stars in each WB. We interpolate between the Newtonian and Milgromian predictions using the parameter $\alpha_{\rm{grav}}$, with 0 indicating Newtonian gravity and 1 indicating MOND. Directly comparing the best Newtonian and Milgromian models reveals that Newtonian dynamics is preferred at $19\sigma$ confidence. Using a complementary Markov Chain Monte Carlo analysis, we find that $\alpha_{\rm{grav}} = -0.021^{+0.065}_{-0.045}$, which is fully consistent with Newtonian gravity but excludes MOND at $16\sigma$ confidence. This is in line with the similar result of Pittordis and Sutherland using a somewhat different sample selection and less thoroughly explored population model. We show that although our best-fitting model does not fully reproduce the observations, an overwhelmingly strong preference for Newtonian gravity remains in a considerable range of variations to our analysis. Adapting the MOND interpolating function to explain this result would cause tension with rotation curve constraints. We discuss the broader implications of our results in light of other works, concluding that MOND must be substantially modified on small scales to account for local WBs.

We present a simple and promising new method to measure the expansion rate and the geometry of the universe that combines observations related to the time delays between the multiple images of time-varying sources, strongly lensed by galaxy clusters, and Type Ia supernovae, exploding in galaxies belonging to the same lens clusters. By means of two different statistical techniques that adopt realistic errors on the relevant quantities, we quantify the accuracy of the inferred cosmological parameter values. We show that the estimate of the Hubble constant is robust and competitive, and depends only mildly on the chosen cosmological model. Remarkably, the two probes separately produce confidence regions on the cosmological parameter planes that are oriented in complementary ways, thus providing in combination valuable information on the values of the other cosmological parameters. We conclude by illustrating the immediate observational feasibility of the proposed joint method in a well-studied lens galaxy cluster, with a relatively small investment of telescope time for monitoring from a 2 to 3m class ground-based telescope.

We explore the effect of ionizing UV background (UVB) on the redshift space clustering of low-$\textit{z}$ ($\textit{z} \leq 0.5$) OVI absorbers using Sherwood simulations incorporating "WIND" (i.e. outflows driven by stellar feedback) only and "AGN+WIND" feedbacks. These simulations show a positive clustering signals up to a scale of 3 Mpc. We find that the effect of feedback is restricted to small scales (i.e $\leq$ 2 Mpc or 200 $\textit{kms}^{-1} $ at $\textit{z}$ ~ 0.3) and "WIND" only simulations produce stronger clustering signal compared to simulations incorporating "AGN+WIND" feedbacks. How clustering signal is affected by the assumed UVB depends on the feedback processes assumed. For the simulations considered here the effect of UVB is confined to even smaller scales (i.e <1 Mpc or $\approx 100\textit{kms}^{-1}$ at $\textit{z}$ ~ 0.3). These scales are also affected by exclusion caused by line blending. Therefore, our study suggests clustering at intermediate scales (i.e 1-2 Mpc for simulations considered here) together with the observed column density distribution can be used to constrain the effect of feedback in simulations.

The cosmic dawn 21-cm signal is enabled by Ly~$\alpha$ photons through a process called the Wouthuysen-Field effect. An accurate model of the signal in this epoch hinges on the accuracy of the computation of the Ly~$\alpha$ coupling, which requires one to calculate the specific intensity of UV radiation from sources such as the first stars. Most traditional calculations of the Ly~$\alpha$ coupling assume a delta-function scattering cross-section, as the resonant nature of the Ly~$\alpha$ scattering makes an accurate radiative transfer solution computationally expensive. Attempts to improve upon this traditional approach using numerical radiative transfer have recently emerged. However, the radiative transfer computation in these treatments suffers from assumptions such as a uniform density of intergalactic gas, zero gas temperature, and absence of gas bulk motion, or numerical approximations such as core skipping. We investigate the role played by these approximations in setting the value of the Ly~$\alpha$ coupling and the 21-cm signal at cosmic dawn. We present results of Monte Carlo radiative transfer simulations, without core skipping, and show that neglecting gas temperature in the radiative transfer significantly underestimates the scattering rate and hence the Ly~$\alpha$ coupling and the 21-cm signal. We also discuss the effect of these processes on the 21-cm power spectrum from the cosmic dawn. This work points the way towards higher-accuracy models to enable better inferences from future measurements.

Optical circular polarization observations can directly test the particle composition in black holes jets. Here we report on the first observations of the BL Lac type object S4 0954+65 in high linear polarized states. While no circular polarization was detected, we were able to place upper limits of <0.5% at the 99.7% confidence. Using a simple model and our novel optical circular polarization observations we can constrain the allowed parameter space for the magnetic field strength and composition of the emitting particles. Our results favor models that require magnetic field strengths of only a few Gauss and models where the jet composition is dominated by electron-positron pairs. We discuss our findings in the context of typical magnetic field strength requirements for blazar emission models.

We present a study of molecular gas, traced via CO (3-2) from ALMA data, of four z< 0.2, `radio quiet', type 2 quasars (log [L(bol)/(erg/s)] = 45.3 - 46.2; log [L(1.4 GHz)/(W/Hz)] = 23.7 - 24.3). Targets were selected to have extended radio lobes (>= 10 kpc), and compact, moderate-power jets (1 - 10 kpc; log [Pjet/(erg/s)]= 43.2 - 43.7). All targets show evidence of central molecular outflows, or injected turbulence, within the gas disks (traced via high-velocity wing components in CO emission-line profiles). The inferred velocities (Vout = 250 - 440 km/s) and spatial scales (0.6 - 1.6 kpc), are consistent with those of other samples of luminous low-redshift AGN. In two targets, we observe extended molecular gas structures beyond the central disks, containing 9 - 53 % of the total molecular gas mass. These structures tend to be elongated, extending from the core, and wrap-around (or along) the radio lobes. Their properties are similar to the molecular gas filaments observed around radio lobes of, mostly `radio loud', Brightest Cluster Galaxies. They have: projected distances of 5 - 13 kpc; bulk velocities of 100 - 340 km/s; velocity dispersion of 30 - 130 km/s; inferred mass outflow rates of 4 - 20 Msolar/yr; and estimated kinetic powers of log [Ekin/(erg/s)]= 40.3 - 41.7. Our observations are consistent with simulations that suggest moderate-power jets can have a direct (but modest) impact on molecular gas on small scales, through direct jet-cloud interactions. Then, on larger scales, jet-cocoons can push gas aside. Both processes could contribute to the long-term regulation of star formation.

In this paper, we use Topological Data Analysis (TDA), a mathematical approach for studying data shape, to analyse Fast Radio Bursts (FRBs). Applying the Mapper algorithm, we visualise the topological structure of a large FRB sample. Our findings reveal three distinct FRB populations based on their inferred source properties, and show a robust structure indicating their morphology and energy. We also identify potential non-repeating FRBs that might become repeaters based on proximity in the Mapper graph. This work showcases TDA's promise in unraveling the origin and nature of FRBs.

In order to shed light on the characteristics of the broad line region (BLR) in a narrow-line Seyfert 1 galaxy, we present an analysis of X-ray, UV, and optical spectroscopic observations of the broad emission lines in Mrk 110. For the broad-band modelling of the emission-line luminosity, we adopt the `locally optimally emitting cloud' approach, which allows us to place constraints on the gas radial and density distribution. By exploring additional environmental effects, we investigate the possible scenarios resulting in the observed spectra. We find that the photoionised gas in Mrk 110 responsible for the UV emission can fully account for the observed low-ionisation X-ray lines. The overall ionisation of the gas is lower, and one radial power-law distribution with a high integrated covering fraction $C_{\mathrm{f}} \approx 0.5$ provides an acceptable description of the emission lines spanning from X-rays to the optical band. The BLR is likely more compact than the broad-line Seyfert 1s studied so far, extending from $\sim\!10^{16}$ to $\sim\!10^{18}$ cm, and limited by the dust sublimation radius at the outer edge. Despite the large colour excess predicted by the Balmer ratio, the best fit suggests $E(B-V)\approx0.03$ for both the ionising luminosity and the BLR, indicating that extinction might be uniform over a range of viewing angles. While the adopted data-modelling technique does not allow us to place constraints on the geometry of the BLR, we show that the addition of models with a clumpy, equatorial, wind-like structure may lead to a better description of the observed spectra.

Swift J1357.2-0933 is a black hole transient of particular interest due to the optical, recurrent dips found during its first two outbursts (in 2011 and 2017), with no obvious X-ray equivalent. We present fast optical photometry during its two most recent outbursts, in 2019 and 2021. Our observations reveal that the optical dips were present in every observed outburst of the source, although they were shallower and showed longer recurrence periods in the two most recent and fainter events. We perform a global study of the dips properties in the four outbursts, and find that they do not follow a common temporal evolution. In addition, we discover a correlation with the X-ray and optical fluxes, with dips being more profound and showing shorter recurrence periods for brighter stages. This trend seems to extend even to the faintest, quiescent states of the source. Finally, we discuss these results in the context of the possible connection between optical dips and outflows found in previous works.

In `spider' pulsars, the X-ray band is dominated by Intrabinary Shock (IBS) synchrotron emission. While the double-peaked X-ray light curves from these shocks have been well characterized in several spider systems (both black widows and redbacks), the polarization of this emission is yet to be studied. Motivated by the new polarization capability of the Imaging X-ray Polarization Explorer (IXPE) and the confirmation of highly ordered magnetic fields in pulsar wind nebulae, we model the IBS polarization, employing two potential magnetic field configurations: toroidal magnetic fields imposed by the pre-shock pulsar wind, and tangential shock-generated fields, which follow the post-shock flow. We find that if IBSs host ordered magnetic fields, the synchrotron X-rays from spider binaries can display a high degree of polarization ($\gtrsim50\%$), while the polarization angle variation provides a good probe of the binary geometry and the magnetic field structure. Our results encourage polarization observational studies of spider pulsars, which can distinguish the proposed magnetic models and better constrain unique properties of these systems.

The goal of this work is to characterize the polarization effects of the VLTI and GRAVITY. This is needed to calibrate polarimetric observations with GRAVITY for instrumental effects and to understand the systematic error introduced to the astrometry due to birefringence when observing targets with a significant intrinsic polarization. By combining a model of the VLTI light path and its mirrors and dedicated experimental data, we construct a full polarization model of the VLTI UTs and the GRAVITY instrument. We first characterize all telescopes together to construct a UT calibration model for polarized targets. We then expand the model to include the differential birefringence. With this, we can constrain the systematic errors for highly polarized targets. Together with this paper, we publish a standalone Python package to calibrate the instrumental effects on polarimetric observations. This enables the community to use GRAVITY to observe targets in a polarimetric observing mode. We demonstrate the calibration model with the galactic center star IRS 16C. For this source, we can constrain the polarization degree to within 0.4 % and the polarization angle within 5 deg while being consistent with the literature. Furthermore, we show that there is no significant contrast loss, even if the science and fringe-tracker targets have significantly different polarization, and we determine that the phase error in such an observation is smaller than 1 deg, corresponding to an astrometric error of 10 {\mu}as. With this work, we enable the use of the polarimetric mode with GRAVITY/UTs and outline the steps necessary to observe and calibrate polarized targets. We demonstrate that it is possible to measure the intrinsic polarization of astrophysical sources with high precision and that polarization effects do not limit astrometric observations of polarized targets.

We present an eigenfunction method to analyze 161 visual light curves (LCs) of Type Ia supernovae (SNe Ia) obtained by the Carnegie Supernova Project to characterize their diversity and host-galaxy correlations. The eigenfunctions are based on the delayed-detonation scenario using three parameters: the LC stretch being determined by the amount of deflagration-burning governing the 56Ni production, the main-sequence mass M_MS of the progenitor white dwarf controlling the explosion energy, and its central density rho_c shifting the 56Ni distribution. Our analysis tool (SPAT) extracts the parameters from observations and projects them into physical space using their allowed ranges M_MS < 8 M_sun, rho_c < 7-8x10^9g/cc. The residuals between fits and individual LC-points are ~ 1-3% for ~ 92% of objects. We find two distinct M_MS groups corresponding to a fast (~ 40-65 Myrs) and a slow(~ 200-500 Myrs) stellar evolution. Most underluminous SNe Ia have hosts with low star formation but high M_MS, suggesting slow evolution times of the progenitor system. 91T-likes SNe show very similar LCs and high M_MS and are correlated to star formation regions, making them potentially important tracers of star formation in the early Universe out to z = 4-11. Some 6% outliers with `non-physical' parameters can be attributed to superluminous SNe Ia and subluminous SNe Ia with hosts of active star formation. For deciphering the SNe Ia diversity and high-precision SNe Ia cosmology, the importance is shown for LCs covering out to ~ 60 days past maximum. Finally, our method and results are discussed within the framework of multiple explosion scenarios, and in light of upcoming surveys.

Thermal inertia estimates are available for a limited number of a few hundred objects, and the results are practically solely based on thermophysical modeling (TPM). We present a novel thermal inertia estimation method, Asteroid Thermal Inertia Analyzer (ASTERIA). The core of the ASTERIA model is the Monte Carlo approach, based on the Yarkovsky drift detection. We validate our model on asteroid Bennu plus ten well-characterized near-Earth asteroids (NEAs) for which a good estimation of the thermal inertia from the TPM exists. The tests show that the ASTERIA provides reliable results consistent with the literature values. The new method is independent from the TPM, allowing an independent verification of the results. As the Yarkovsky effect is more pronounced in small asteroids, the noteworthy advantage of the ASTERIA compared to the TPM is the ability to work with smaller asteroids for which TPM typically lacks the input data. We used the ASTERIA to estimate the thermal inertia of 38 NEAs, with 31 of them being sub-km asteroids. Twenty-nine objects in our sample are characterized as Potentially Hazardous Asteroids. On the limitation side, the ASTERIA is somewhat less accurate than the TPM. The applicability of our model is limited to NEAs, as the Yarkovsky effect is yet to be detected in main-belt asteroids. However, we can expect a significant increase in high-quality measurements of the input parameters relevant to the ASTERIA with upcoming surveys. This will surely increase the reliability of the results generated by the ASTERIA and widen the model's applicability.

This work reports the performance evaluation of an SDR readout system based on the latest generation (Gen3) of the AMD's Radio Frequency System-on-Chip (RFSoC) processing platform, which integrates a full-stack processing system and a powerful FPGA with up to 32 high-speed and high-resolution 14-bit Digital-to-Analog Converters (DACs) and Analog-to-Digital Converters (ADCs). The proposed readout system uses a previously developed multi-band, double-conversion IQ RF-mixing board targeting a multiplexing factor of approximately 1,000 bolometers in a bandwidth between 4 and 8 GHz, in line with state-of-the-art microwave SQUID multiplexers ($\mu$MUX). The characterization of the system was performed in two stages, under the conditions typically imposed by the multiplexer and the cold readout circuit. First, in transmission, showing that noise and spurious levels of the generated tones are close to the values imposed by the cold readout. Second, in RF loopback, presenting noise values better than -100 dBc/Hz totally in agreement with the state-of-the-art readout systems. It was demonstrated that the RFSoC Gen3 device is a suitable enabling technology for the next generation of superconducting detector readout systems, reducing system complexity, increasing system integration, and achieving these goals without performance degradation.

It was pointed out previously~\cite{Kinney:2014jya} that a sufficiently negative running of the spectral index of curvature perturbations from (ordinary i.e. cold) inflation is able to prevent eternal inflation from ever occurring. Here, we reevaluate those original results, but in the context of warm inflation, in which a substantial radiation component (produced by the inflaton) exists throughout the inflationary period. We demonstrate that the same general requirements found in the context of ordinary (cold) inflation also hold true in warm inflation; indeed an even tinier amount of negative running is sufficient to prevent eternal inflation. This is particularly pertinent, as models featuring negative running are more generic in warm inflation scenarios. Finally, the condition for the existence of eternal inflation in cold inflation -- that the curvature perturbation amplitude exceed unity on superhorizon scales -- becomes more restrictive in the case of warm inflation. The curvature perturbations must be even larger, i.e. even farther out on the potential, away from the part of the potential where observables, e.g. in the Cosmic Microwave Background, are produced.

The halo concentration-mass relation has ubiquitous use in modeling the matter field for cosmological and astrophysical analyses, and including the imprints from galaxy formation physics is tantamount to its robust usage. Many analyses, however, probe the matter around halos selected by a given halo/galaxy property -- rather than by halo mass -- and the imprints under each selection choice can be different. We employ the CAMELS simulation suite to quantify the astrophysics and cosmology dependence of the concentration-mass relation, $c_{\rm vir}-M_{\rm vir}$, when selected on five properties: (i) velocity dispersion, (ii) formation time, (iii) halo spin, (iv) stellar mass, and (v) gas mass. We construct simulation-informed nonlinear models for all properties as a function of halo mass, redshift, and six cosmological/astrophysical parameters, with a mass range $M_{\rm vir} \in [10^{11}, 10^{14.5}] M_\odot/h$. There are many mass-dependent imprints in all halo properties, with clear connections across different properties and non-linear couplings between the parameters. Finally, we extract the $c_{\rm vir}-M_{\rm vir}$ relation for subsamples of halos that have scattered above/below the mean property-$M_{\rm vir}$ relation for a chosen property. Selections on gas mass or stellar mass have a significant impact on the astrophysics/cosmology dependence of $c_{\rm vir}$, while those on any of the other three properties have a significant (mild) impact on the cosmology (astrophysics) dependence. We show that ignoring such selection effects can lead to errors of $\approx 25\%$ in baryon imprint modelling of $c_{\rm vir}$. Our nonlinear model for all properties is made publicly available.

The relatively red wavelength range (4800-9300{\AA}) of the VLT Multi Unit Spectroscopic Explorer (MUSE) limits which metallicity diagnostics can be used; in particular excluding those requiring the [O ii]{\lambda}{\lambda}3726,29 doublet. We assess various strong line diagnostics by comparing to sulphur Te-based metallicity measurements for a sample of 671 HII regions from 36 nearby galaxies from the MUSE Atlas of Disks (MAD) survey. We find that the O3N2 and N2 diagnostics return a narrower range of metallicities which lie up to ~0.3 dex below Te-based measurements, with a clear dependence on both metallicity and ionisation parameter. The N2S2H{\alpha} diagnostic shows a near-linear relation with the Te-based metallicities, although with a systematic downward offset of ~0.2 dex, but no clear dependence on ionisation parameter. These results imply that the N2S2H{\alpha} diagnostic produces the most reliable results when studying the distribution of metals within galaxies with MUSE. On sub-HII region scales, the O3N2 and N2 diagnostics measure metallicity decreasing towards the centres of HII regions, contrary to expectations. The S-calibration and N2S2H{\alpha} diagnostics show no evidence of this, and show a positive relationship between ionisation parameter and metallicity at 12 + log(O/H)> 8.4, implying the relationship between ionisation parameter and metallicity differs on local and global scales. We also present HIIdentify, a python tool developed to identify HII regions within galaxies from H{\alpha} emission maps. All segmentation maps and measured emission line strengths for the 4408 HII regions identified within the MAD sample are available to download.

Polar-ring galaxies are photometrically and kinematically decoupled systems which are highly inclined to the major axis of the host galaxy. These objects have been explored since the 1970s, but the rarity of these systems has made such study difficult. We examine a sample of over 18,362 galaxies from the Sloan Digital Sky Survey (SDSS) Stripe 82 for the presence of galaxies with polar structures. Using deep SDSS Stripe 82, DESI Legacy Imaging Surveys, and Hyper Suprime-Cam Subaru Strategic Program, we select 53 good candidate galaxies with photometrically decoupled polar rings, 9 galaxies with polar halos, and 34 possibly forming polar-ring galaxies, versus 13 polar-ring candidates previously mentioned in the literature for the Stripe 82. Our results suggest that the occurrence rate of galaxies with polar structures may be significantly underestimated, as revealed by the deep observations, and may amount to 1-3% of non-dwarf galaxies.

The observability of afterglows from binary neutron star mergers, occurring within AGN disks is investigated. We perform 3D GRMHD simulations of a post-merger system, and follow the jet launched from the compact object. We use semi-analytic techniques to study the propagation of the blast wave powered by the jet through an AGN disk-like external environment, extending to distances beyond the disk scale height. The synchrotron emission produced by the jet-driven forward shock is calculated to obtain the afterglow emission. The observability of this emission at different frequencies is assessed by comparing it to the quiescent AGN emission. In the scenarios where the afterglow could temporarily outshine the AGN, we find that detection will be more feasible at higher frequencies (> 10^(14) Hz) and the electromagnetic counterpart could manifest as a fast variability in the AGN emission, on timescales less than a day.

The efficiency of tidal dissipation provides a zeroth-order link to a planet's physical properties. For super-Earth and sub-Neptune planets in the range $R_{\oplus}\lesssim R_p \lesssim 4 R_{\oplus}$, particularly efficient dissipation (i.e., low tidal quality factors) may signify terrestrial-like planets capable of maintaining rigid crustal features. Here we explore global constraints on planetary tidal quality factors using a population of planets in multiple-planet systems whose orbital and physical properties indicate susceptibility to capture into secular spin-orbit resonances. Planets participating in secular spin-orbit resonance can maintain large axial tilts and significantly enhanced heating from obliquity tides. When obliquity tides are sufficiently strong, planets in low-order mean-motion resonances can experience resonant repulsion (period ratio increase). The observed distribution of period ratios among transiting planet pairs may thus depend non-trivially on the underlying planetary structures. We model the action of resonant repulsion and demonstrate that the observed distribution of period ratios near the 2:1 and 3:2 commensurabilties implies $Q$ values spanning from $Q\approx 10^1-10^7$ and peaking at $Q \approx 10^6$. This range includes the expected range in which super-Earth and sub-Neptune planets dissipate ($Q \approx 10^3 - 10^4$). This work serves as a proof of concept for a method of assessing the presence of two dissipation regimes, and we estimate the number of additional multi-transiting planetary systems needed to place any bimodality in the distribution on a strong statistical footing.

In this study, we highlight the capacity of current and forthcoming air shower arrays utilizing water-Cherenkov stations to detect neutrino events spanning energies from $10\,$GeV to $100\,$TeV. This detection approach leverages individual stations equipped with both bottom and top photosensors, making use of features of the signal time trace and machine learning techniques. Our findings demonstrate the competitiveness of this method compared to established and future neutrino-detection experiments, including IceCube and the upcoming Hyper-Kamiokande experiment.

Dark matter haloes grow at a rate that depends on the value of the cosmological parameters $\sigma_8$ and $\Omega_{\rm m}$ through the initial power spectrum and the linear growth factor. While halo abundance is routinely used to constrain these parameters, through cluster abundance studies, the halo growth rate is not. In recent work, we proposed constraining the cosmological parameters using observational estimates of the overall dynamical "age" of clusters, expressed, for instance, by their half-mass assembly redshift $z_{50}$. Here we explore the prospects for using the instantaneous growth rate, as estimated from the halo merger rate, from the average growth rate over the last dynamical time, or from the fraction of systems with recent episodes of major growth. We show that the merger rate is mainly sensitive to the amplitude of fluctuations $\sigma_8$, while the rates of recent growth provide constraints in the $\Omega_{\rm m}$-$\sigma_8$ plane that are almost orthogonal to those provided by abundance studies. Data collected for forthcoming cluster abundance studies, or studies of the galaxy merger rate in current and future galaxy surveys, may thus provide additional constraints on the cosmological parameters complementary to those already derived from halo abundance.

The PRobe far-Infrared Mission for Astrophysics (PRIMA) is under study as a potential far-IR space mission, featuring actively cooled optics, and both imaging and spectroscopic instrumentation. To fully take advantage of the low background afforded by a cold telescope, spectroscopy with PRIMA requires detectors with a noise equivalent power (NEP) better than $1 \times 10^{-19}$ W Hz$^{-1/2}$. To meet this goal we are developing large format arrays of kinetic inductance detectors (KIDs) to work across the $25-250$ micron range. Here we present the design and characterization of a single pixel prototype detector optimized for $210$ micron. The KID consist of a lens-coupled aluminum inductor-absorber connected to a niobium interdigitated capacitor to form a 2 GHz resonator. We measure the performance of this detector with optical loading in the $0.01 - 300$ aW range. At low loading the detector achieves an NEP of $9\times10^{-20}$ W Hz$^{-1/2}$ at a 10 Hz readout frequency, and the lens-absorber system achieves a good optical efficiency. An extrapolation of these measurements suggest this detector may remain photon noise limited at up to 20 fW, offering a high dynamic range for PRIMA observations of bright astronomical sources.

Since the 1970s, astronomers have struggled with the issue of how matter can be accreted to promote black hole growth. While low-angular-momentum stars may be devoured by the black hole, they are not a sustainable source of fuel. Gas, which could potentially provide an abundant fuel source, presents another challenge due to its enormous angular momentum. While viscous torques are not significant, gas is subject to gravity torques from non-axisymmetric potentials such as bars and spirals. Primary bars can exchange angular momentum with the gas inside corotation, driving it inward spiraling until the inner Lindblad resonance is reached. An embedded nuclear bar can then take over. As the gas reaches the black hole's sphere of influence, the torque turns negative, fueling the center. Dynamical friction also accelerates the infall of gas clouds closer to the nucleus. However, due to the Eddington limit, growing a black hole from a stellar-mass seed is a slow process. The existence of very massive black holes in the early universe remains a puzzle that could potentially be solved through direct collapse of massive clouds into black holes or super-Eddington accretion.

The variable continuum emission of an active galactic nucleus (AGN) produces corresponding responses in the broad emission lines, which are modulated by light travel delays, and contain information on the physical properties, structure, and kinematics of the emitting gas region. The reverberation mapping technique, a time series analysis of the driving light curve and response, can recover some of this information, including the size and velocity field of the broad line region (BLR). Here we introduce a new forward-modeling tool, the Broad Emission Line MApping Code (BELMAC), which simulates the velocity-resolved reverberation response of the BLR to any given input light curve by setting up a 3D ensemble of gas clouds for various specified geometries, velocity fields, and cloud properties. In this work, we present numerical approximations to the transfer function by simulating the velocity-resolved responses to a single continuum pulse for sets of models representing a spherical BLR with a radiatively driven outflow and a disk-like BLR with Keplerian rotation. We explore how the structure, velocity field, and other BLR properties affect the transfer function. We calculate the response-weighted time delay (reverberation "lag"), which is considered to be a proxy for the luminosity-weighted radius of the BLR. We investigate the effects of anisotropic cloud emission and matter-bounded (completely ionized) clouds and find the response-weighted delay is only equivalent to the luminosity-weighted radius when clouds emit isotropically and are radiation-bounded (partially ionized). Otherwise, the luminosity-weighted radius can be overestimated by up to a factor of 2.

Fuzzy Dark Matter (FDM) has recently emerged as an interesting alternative model to the standard Cold Dark Matter (CDM). In this model, dark matter consists of very light bosonic particles with quantum mechanical effects on galactic scales. Using the N-body code AX-GADGET, we perform cosmological simulations of FDM that fully model the dynamical effects of the quantum potential throughout cosmic evolution. Through the combined analysis of FDM volume and high-resolution zoom-in simulations of different FDM particle masses ($m_{\chi}$ $\sim$ $10^{-23} - 10^{-21}$ eV/c$^2$), we study how FDM impacts the abundance of substructure and the inner density profiles of dark matter haloes. For the first time, using our FDM volume simulations, we provide a fitting formula for the FDM-to-CDM subhalo abundance ratio as a function of the FDM mass. More importantly, our simulations clearly demonstrate that there exists an extended FDM particle mass interval able to reproduce the observed substructure counts and, at the same time, create substantial cores ($r_{c} \sim 1$ kpc) in the density profile of dwarf galaxies ($\approx 10^{9}-10^{10}$ M$_{\odot}$), which stands in stark contrast with CDM predictions even with baryonic effects taken into account. The dark matter distribution in the faintest galaxies offers then a clear way to discriminate between FDM and CDM.

Coronal Mass Ejections (CMEs) are immense eruptions of plasma and magnetic fields that are propelled outward from the Sun, sometimes with velocities greater than 2000 km/s. They are responsible for some of the most severe space weather at Earth, including geomagnetic storms and solar energetic particle (SEP) events. We have developed CORHEL-CME, an interactive tool that allows non-expert users to routinely model multiple CMEs in a realistic coronal and heliospheric environment. The tool features a web-based user interface that allows the user to select a time period of interest, and employs RBSL flux ropes to create stable and unstable pre-eruptive configurations within a background global magnetic field. The properties of these configurations can first be explored in a zero-beta magnetohydrodynamic (MHD) model, followed by complete CME simulations in thermodynamic MHD, with propagation out to 1 AU. We describe design features of the interface and computations, including the innovations required to efficiently compute results on practical timescales with moderate computational resources. CORHEL-CME is now implemented at NASA's Community Coordinated Modeling Center (CCMC) using NASA Amazon Web Services (AWS). It will be available to the public by the time this paper is published.

While proper orbital elements are currently available for more than 1 million asteroids, taxonomical information is still lagging behind. Surveys like SDSS-MOC4 provided preliminary information for more than 100,000 objects, but many asteroids still lack even a basic taxonomy. In this study, we use Dark Energy Survey (DES) data to provide new information on asteroid physical properties. By cross-correlating the new DES database with other databases, we investigate how asteroid taxonomy is reflected in DES data. While the resolution of DES data is not sufficient to distinguish between different asteroid taxonomies within the complexes, except for V-type objects, it can provide information on whether an asteroid belongs to the C- or S-complex. Here, machine learning methods optimized through the use of genetic algorithms were used to predict the labels of more than 68,000 asteroids with no prior taxonomic information. Using a high-quality, limited set of asteroids with data on $gri$ slopes and $i-z$ colors, we detected 409 new possible V-type asteroids. Their orbital distribution is highly consistent with that of other known V-type objects.

The immense diversity of the galaxy population in the universe is believed to stem from their disparate merging histories, stochastic star formations, and multi-scale influences of filamentary environments. Any single initial condition of the early universe was never expected to explain alone how the galaxies formed and evolved to end up possessing such various traits as they have at the present epoch. However, several observational studies have revealed that the key physical properties of the observed galaxies in the local universe appeared to be regulated by one single factor, the identity of which has been shrouded in mystery up to date. Here, we report on our success of identifying the single regulating factor as the degree of misalignments between the initial tidal field and protogalaxy inertia momentum tensors. The spin parameters, formation epochs, stellar-to-total mass ratios, stellar ages, sizes, colors, metallicities and specific heat energies of the galaxies from the IllustrisTNG suite of hydrodynamic simulations are all found to be almost linearly and strongly dependent on this initial condition, when the differences in galaxy total mass, environmental density and shear are controlled to vanish. The cosmological predispositions, if properly identified, turns out to be much more impactful on galaxy evolution than conventionally thought.

Although low-frequency quasiperiodic oscillations (LFQPOs) are commonly detected in the X-ray light curves of accreting black hole X-ray binaries, their origin still remains elusive. In this study, we conduct phase-resolved spectroscopy in a broad energy band for LFQPOs in MAXI J1820+070 during its 2018 outburst, utilizing Insight-HXMT observations. By employing the Hilbert-Huang transform method, we extract the intrinsic quasiperiodic oscillation (QPO) variability, and obtain the corresponding instantaneous amplitude, phase, and frequency functions for each data point. With well-defined phases, we construct QPO waveforms and phase-resolved spectra. By comparing the phase-folded waveform with that obtained from the Fourier method, we find that phase folding on the phase of the QPO fundamental frequency leads to a slight reduction in the contribution of the harmonic component. This suggests that the phase difference between QPO harmonics exhibits time variability. Phase-resolved spectral analysis reveals strong concurrent modulations of the spectral index and flux across the bright hard state. The modulation of the spectral index could potentially be explained by both the corona and jet precession models, with the latter requiring efficient acceleration within the jet. Furthermore, significant modulations in the reflection fraction are detected exclusively during the later stages of the bright hard state. These findings provide support for the geometric origin of LFQPOs and offer valuable insights into the evolution of the accretion geometry during the outburst in MAXI J1820+070.

We report on IXPE, NICER and XMM-Newton observations of the magnetar 1E 2259+586. We find that the source is significantly polarized at about or above 20% for all phases except for the secondary peak where it is more weakly polarized. The polarization degree is strongest during the primary minimum which is also the phase where an absorption feature has been identified previously (Pizzocaro et al. 2019). The polarization angle of the photons are consistent with a rotating vector model with a mode switch between the primary minimum and the rest of the rotation of the neutron star. We propose a scenario in which the emission at the source is weakly polarized (as in a condensed surface) and, as the radiation passes through a plasma arch, resonant cyclotron scattering off of protons produces the observed polarized radiation. This confirms the magnetar nature of the source with a surface field greater than about 10¹⁵ G

In an accreting X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the inner edge of the disc, funneling the gas to flow onto the magnetic poles on its surface. Hercules X-1 is in many ways the prototypical X-ray pulsar; it shows persistent X-ray emission and it resides with its companion HZ Her, a two-solar-mass star, at about 7~kpc from Earth. Its emission varies on three distinct timescales: the neutron star rotates every 1.2~seconds, it is eclipsed by its companion each 1.7~days, and the system exhibits a superorbital period of 35~days which has remained remarkably stable since its discovery. Several lines of evidence point to the source of this variation as the precession of the accretion disc, the precession of the neutron star or both. Despite the many hints over the past fifty years, the precession of the neutron star itself has yet not been confirmed or refuted. We here present X-ray polarization measurements with the Imaging X-ray Polarimetry Explorer (IXPE) which probe the spin geometry of the neutron star. These observations provide direct evidence that the 35-day-period is set by the free precession of the neutron star crust, which has the important implication that its crust is somewhat asymmetric fractionally by a few parts per ten million. Furthermore, we find indications that the basic spin geometry of the neutron star is altered by torques on timescale of a few hundred days.

The classifications of Fermi-LAT unassociated sources are studied using multiple machine learning (ML) methods. The update data from 4FGL-DR3 are divided into high Galactic latitude (HGL, Galactic latitude $|b|>10^\circ$) and low Galactic latitude (LGL, $|b|\le10^\circ$) regions. In the HGL region, a voting ensemble of four binary ML classifiers achieves a 91$\%$ balanced accuracy. In the LGL region, an additional Bayesian-Gaussian (BG) model with three parameters is introduced to eliminate abnormal soft spectrum AGNs from the training set and ML-identified AGN candidates, a voting ensemble of four ternary ML algorithms reach an 81$\%$ balanced accuracy. And then, a catalog of Fermi-LAT all-sky unassociated sources is constructed. Our classification results show that (i) there are 1037 AGN candidates and 88 pulsar candidates with a balanced accuracy of $0.918 \pm 0.029$ in HGL region, which are consistent with those given in previous all-sky ML approaches; and (ii) there are 290 AGN-like candidates, 135 pulsar-like candidates, and 742 other-like candidates with a balanced accuracy of $0.815 \pm 0.027$ in the LGL region, which are different from those in previous all-sky ML approaches. Additionally, different training sets and class weights were tested for their impact on classifier accuracy and predicted results. The findings suggest that while different training approaches can yield similar model accuracy, the predicted numbers across different categories can vary significantly. Thus, reliable evaluation of the predicted results is deemed crucial in the ML approach for Fermi-LAT unassociated sources.

Image degradation impedes our ability to extract information from astronomical observations. One factor contributing to this degradation is ``dome seeing", the reduction in image quality due to variations in the index of refraction within the observatory dome. Addressing this challenge, we introduce a novel setup-DIMSUM (Differential Image Motion Sensor Using Multisources)-which offers a simple installation and provides direct characterization of local index of refraction variations. This is achieved by measuring differential image motion using strobed imaging that effectively``freezes" the atmosphere, aligning our captured images with the timescale of thermal fluctuations, thereby giving a more accurate representation of dome seeing effects. Our apparatus has been situated within the Auxiliary Telescope of the Vera C. Rubin Observatory. Early results from our setup are encouraging. Not only do we observe a correlation between the characteristic differential image motion (DIM) values and local temperature fluctuations (a leading cause of variations in index of refraction), but also hint at the potential of DIM measures to characterize dome seeing with greater precision in subsequent tests. Our preliminary findings underscore the potential of DIMSUM as a powerful tool for enhancing image quality in ground-based astronomical observations. Further refinement and data collection will likely solidify its place as a useful component for managing dome seeing in major observatories like the Vera C. Rubin Observatory.

On August 25th 2013 Dana Patchick from the "Deep Sky Hunters" (DSH) amateur astronomer group discovered a diffuse nebulosity in the Wide-field Infrared Survey Explorer (WISE) mid-IR image archive that had no optical counterpart but appeared similar to many Planetary Nebulae (PNe) in WISE. As his 30th discovery he named it Pa 30 and it was added to the HASH PN database as a new PN candidate. Little did he know how important his discovery would become. 10 years later this object is the only known bound remnant of a violent double WD merger accompanied by a rare Type Iax SN, observed and recorded by the ancient Chinese and Japanese in 1181 AD. This makes Pa 30 and its central star IRAS 00500+6713 (WD J005311) the only SN Iax remnant in our Galaxy, the only known bound remnant of any SN, and based on the central star's spectrum the only Wolf-Rayet star known that neither has a massive progenitor nor is the central star of a Planetary Nebula. We cover this story and our key role in it.

We present a hierarchical Bayesian inference approach to estimating the structural properties and the phase space center of a globular cluster (GC) given the spatial and kinematic information of its stars based on lowered isothermal cluster models. As a first step towards more realistic modelling of GCs, we built a differentiable, accurate emulator of the lowered isothermal distribution function using interpolation. The reliable gradient information provided by the emulator allows the use of Hamiltonian Monte Carlo methods to sample large Bayesian models with hundreds of parameters, thereby enabling inference on hierarchical models. We explore the use of hierarchical Bayesian modelling to address several issues encountered in observations of GC including an unknown GC center, incomplete data, and measurement errors. Our approach not only avoids the common technique of radial binning but also incorporates the aforementioned uncertainties in a robust and statistically consistent way. Through demonstrating the reliability of our hierarchical Bayesian model on simulations, our work lays out the foundation for more realistic and complex modelling of real GC data.

Context. Standing slow-mode rarefaction and compression front structures may appear in the Mercury magnetosheath under particular solar wind conditions. Aims. The aim of the study is to identify the wind conditions required for the formation of slow-mode structures (SMS) in the Mercury magnetosphere by comparing MESSENGER magnetometer data and magnetohydrodynamics simulations. Methods. We used the magnetohydrodynamics code PLUTO in spherical coordinates to reproduce the interaction of the solar wind with the Mercury magnetosphere. First, the optimal wind conditions for the SMS formation were identified with respect to the orientation of the interplanetary magnetic field (IMF) and dynamic pressure. Next, the magnetic field calculated in the simulations along the MESSENGER trajectory was compared to MESSENGER magnetometer data to identify tracers of the satellite encounter with the SMS. Results. Optimal wind conditions for the formation of SMS require that the IMF is oriented in the northward or radial directions. The MESSENGER orbit on 8th September 2011 takes place during wind conditions that are close to the optimal configuration for SMS formation near the north pole, leading to the possible intersection of the satellite trajectory with the SMS. MESSENGER magnetometer data show a rather strong decrease in the magnetic field module after the satellite crossed nearby the compression front that is observed in the simulation, providing indirect evidence of the SMS.

The aim of this study is to analyze the Earth habitability with respect to the direct exposition of the Earth atmosphere to the solar wind along the Suns evolution on the main sequence including the realistic evolution of the space weather conditions and the Earth magnetic field. The MHD code PLUTO in spherical coordinates is applied to perform parametric studies with respect to the solar wind dynamic pressure and the interplanetary magnetic field intensity for different Earth magnetic field configurations. Quiet space weather conditions may not impact the Earth habitability. On the other hand, the impact of interplanetary coronal mass ejections (ICME) could lead to the erosion of the primary Earth atmosphere during the Hadean eon. A dipolar field of 30 microT is strong enough to shield the Earth from the Eo-Archean age as well as 15 and 5 microT dipolar fields from the Meso-Archean and Meso-Proterozoic, respectively. Multipolar weak field period during the Meso-Proterozoic age may not be a threat for ICME-like space weather conditions if the field intensity is at least 15 microT and the ratio between the quadrupolar (Q) and dipolar (D) coefficients is Q/D <= 0.5. By contrast, the Earth habitability in the Phanerozoic eon (including the present time) can be hampered during multipolar low field periods with a strength of 5 microT and Q/D >= 0.5 associated to geomagnetic reversals. Consequently, the effect of the solar wind should be considered as a possible driver of Earth's habitability.

Traditional spectral analysis methods are increasingly challenged by the exploding volumes of data produced by contemporary astronomical surveys. In response, we develop deep-Regularized Ensemble-based Multi-task Learning with Asymmetric Loss for Probabilistic Inference ($\rm{deep-REMAP}$), a novel framework that utilizes the rich synthetic spectra from the PHOENIX library and observational data from the MARVELS survey to accurately predict stellar atmospheric parameters. By harnessing advanced machine learning techniques, including multi-task learning and an innovative asymmetric loss function, $\rm{deep-REMAP}$ demonstrates superior predictive capabilities in determining effective temperature, surface gravity, and metallicity from observed spectra. Our results reveal the framework's effectiveness in extending to other stellar libraries and properties, paving the way for more sophisticated and automated techniques in stellar characterization.

Dynamical friction can be a valuable tool for inferring dark matter properties that are difficult to constrain by other methods. Most applications of dynamical friction calculations are concerned with the long-term angular momentum loss and orbital decay of the perturber within its host. This, however, assumes knowledge of the unknown initial conditions of the system. We advance an alternative methodology to infer the host properties from the perturber's shape distortions induced by the tides of the wake of dynamical friction, which we refer to as the tidal dynamical friction. As the shape distortions rely on the tidal field that has a predominantly local origin, we present a strategy to find the local wake by integrating the stellar orbits back in time along with the perturber, then removing the perturber's potential and re-integrating them back to the present. This provides perturbed and unperturbed coordinates and hence a change in coordinates, density, and acceleration fields, which yields the back-reaction experienced by the perturber. The method successfully recovers the tidal field of the wake based on a comparison with N-body simulations. We show that similar to the tidal field itself, the noise and randomness of the dynamical friction force due to the finite number of stars is also dominated by regions close to the perturber. Stars near the perturber influence it more but are smaller in number, causing a high variance in the acceleration field. These fluctuations are intrinsic to dynamical friction. We show that a stellar density of $0.0014 {\rm M_\odot\, kpc^{-3}}$ yields an inherent variance of 10% to the dynamical friction. The current method extends the family of dynamical friction methods that allow for the inference of host properties from tidal forces of the wake. It can be applied to specific galaxies, such as Magellanic Clouds, with Gaia data.

The KM3NeT neutrino telescope is currently being deployed at two different sites in the Mediterranean Sea. First searches for astrophysical neutrinos have been performed using data taken with the partial detector configuration already in operation. The paper presents the results of two independent searches for neutrinos from compact binary mergers detected during the third observing run of the LIGO and Virgo gravitational wave interferometers. The first search looks for a global increase in the detector counting rates that could be associated with inverse beta decay events generated by MeV-scale electron anti-neutrinos. The second one focuses on upgoing track-like events mainly induced by muon (anti-)neutrinos in the GeV--TeV energy range. Both searches yield no significant excess for the sources in the gravitational wave catalogs. For each source, upper limits on the neutrino flux and on the total energy emitted in neutrinos in the respective energy ranges have been set. Stacking analyses of binary black hole mergers and neutron star-black hole mergers have also been performed to constrain the characteristic neutrino emission from these categories.

Astronomical data reduction is usually done with processing pipelines that consist of a series of individual processing steps that can be executed stand-alone. These processing steps are then strung together into workflows and fed with data to address a particular processing goal. In this paper, we propose a data processing system that automatically derives processing workflows for different use cases from a single specification of a cascade of processing steps. The system works by using formalized descriptions of data processing pipelines that specify the input and output of each processing step. Inputs can be existing data or the output of a previous step. Rules to select the most appropriate input data are directly attached to the description. A version of the proposed system has been implemented as the ESO Data Processing System (EDPS) in the Python language. The specification of processing cascades and data organisation rules use a restrictive set of Python classes, attributes and functions. The EDPS implementation of the proposed system was used to demonstrate that it is possible to automatically derive from a single specification of a pipeline processing cascade the workflows that the European Southern Observatory uses for quality control, archive production, and specialized science reduction. The EDPS will be used to replace all data reduction systems using different workflow specifications that are currently used at the European Southern Observatory.

We describe a novel operator-splitting approach to numerical relativistic magnetohydrodynamics designed to expand its applicability to the domain of ultra-high magnetisation. In this approach, the electromagnetic field is split into the force-free component, governed by the equations of force-free degenerate electrodynamics (FFDE), and the perturbation component, governed by the perturbation equations derived from the full system of relativistic magnetohydrodynamics (RMHD). The combined system of the FFDE and perturbation equations is integrated simultaneously, for which various numerical techniques developed for hyperbolic conservation laws can be used. At the end of every time-step of numerical integration, the force-free and the perturbation components of the electromagnetic field are recombined and the result is regarded as the initial value of the force-free component for the next time-step, whereas the initial value of the perturbation component is set to zero. To explore the potential of this approach, we build a 3rd-order WENO code, which was used to carry out 1D and 2D test simulations. Their results show that this operator-splitting approach allows us to bypass the stiffness of RMHD in the ultra-high-magnetisation regime where the perturbation component becomes very small. At the same time, the cod

The cosmological model with an interaction between dynamical quintessence dark energy and cold dark matter is considered. Evolution of a dark energy equation of state parameter is defined by a dark energy adiabatic sound speed and a dark sector interaction parameter, which must be more physically correct model then a previously used in which such evolution was given by some fixed dependence on scale factor. The constraints on interaction parameter and other parameters of the model was obtained using a cosmic microwave background, baryon acoustic oscillations and supernova SN Ia data.

Recently we put forward a framework where the dark matter (DM) component within virialized halos is subject to a non-local interaction originated by fractional gravity (FG) effects. In previous works we demonstrated that such a framework can substantially alleviate the small-scale issues of the standard $\Lambda$CDM paradigm, without altering the DM mass profile predicted by $N-$body simulations, and retaining its successes on large cosmological scales. In this paper we dig deeper to probe FG via high-quality data of individual dwarf galaxies, by exploiting the rotation velocity profiles inferred from stellar and gas kinematic measurements in $8$ dwarf irregulars, and the projected velocity dispersion profiles inferred from the observed dynamics of stellar tracers in $7$ dwarf spheroidals and in the ultra-diffuse galaxy DragonFly 44. We find that FG can reproduce extremely well the rotation and dispersion curves of the analysed galaxies, performing in most instances significantly better than the standard Newtonian setup.

Analyzing single-dish and VLBI radio, as well as Fermi-LAT $\gamma$-ray observations, we explained the three major $\gamma$-ray flares in the $\gamma$-ray light curve of FSRQ J1048+7143 with the spin-orbit precession of the dominant mass black hole in a supermassive black hole binary system. Here, we report on the detection of a fourth $\gamma$-ray flare from J1048+7143, appearing in the time interval which was predicted in our previous work. Using the updated analysis covering the time range between 2008 Aug 4 and 2023 Jun 4, we further constrain the parameters of the hypothetical supermassive binary black hole at the heart of J1048+7143 and we predict the occurrence of the fifth major $\gamma$-ray flare that would appear only if the jet will still lay close to our line sight. The fourth major $\gamma$-ray flare also shows the two-subflare structure, further strengthening our scenario in which the occurrence of the subflares is the signature of the precession of a spine-sheath jet structure that quasi-periodically interacts with a proton target, e.g. clouds in the broad-line region.

The study of protoplanetary disc evolution and planet formation has mainly concentrated on solar (and low) mass stars since they host the majority of the confirmed exoplanets. Nevertheless, the numerous planets found orbiting stars up to $\sim3M_\odot$ has sparked interest in understanding how they form and how their hosting discs evolve. Our goal is to improve our knowledge on the gas disc evolution around intermediate mass stars for future planet formation studies. We study the long-term evolution of protoplanetary discs affected by viscous accretion, X-ray and FUV photoevaporation from the central star around stars between $1 - 3M_\odot$ considering the effects of stellar evolution. We explore different values of the viscosity parameter and the initial mass of the disc. We find that the evolutionary pathway of disc dispersal depends on the stellar mass. Our simulations reveal four distinct evolutionary pathways for the gas disc not reported before that are a consequence of stellar evolution, and which will likely impact dust evolution and planet formation. As the stellar mass grows from 1 to $\sim2M_\odot$, the disc evolution changes from the conventional inside-out clearing to a homogeneous disc evolution scenario where both inner and outer discs, formed after photoevaporation opened a gap, vanish over a similar timescale. As the stellar mass continues to increase, reaching $\sim 3M_\odot$, we have identified a distinct pathway that we refer to as revenant disc evolution, where the inner and outer discs reconnect after the gap opened. For the largest masses, we observe outside-in disc dispersal, in which the outer disc dissipates first due to the strong FUV photoevaporation. Revenant disc evolution stands out as it is capable of extending the disc lifespan. Otherwise, the disc dispersal time scale decreases with increasing stellar mass except for low viscosity discs.

Detailed astrochemical models are a key component to interpret the observations of interstellar and circumstellar molecules since they allow important physical properties of the gas and its evolutionary history to be deduced. We update one of the most widely used astrochemical databases to reflect advances in experimental and theoretical estimates of rate coefficients and to respond to the large increase in the number of molecules detected in space since our last release in 2013. We present the sixth release of the UMIST Database for Astrochemistry (UDfA), a major expansion of the gas-phase chemistry that describes the synthesis of interstellar and circumstellar molecules. Since our last release, we have undertaken a major review of the literature which has increased the number of reactions by over 40% to a total of 8767 and increased the number of species by over 55% to 737. We have made a particular attempt to include many of the new species detected in space over the past decade, including those from the QUIJOTE and GOTHAM surveys, as well as providing references to the original data sources. We use the database to investigate the gas-phase chemistries appropriate to O-rich and C-rich conditions in TMC-1 and to the circumstellar envelope of the C-rich AGB star IRC+10216 and identify successes and failures of gas-phase only models. This update is a significant improvement to the UDfA database. For the dark cloud and C-rich circumstellar envelope models, calculations match around 60% of the abundances of observed species to within an order of magnitude. There are a number of detected species, however, that are not included in the model either because their gas-phase chemistry is unknown or because they are likely formed via surface reactions on icy grains. Future laboratory and theoretical work is needed to include such species in reaction networks.

We present the analysis of cloud-cloud collision (CCC) process in the Galactic molecular complex S235. Our new CO observations performed with the PMO-13.7m telescope reveal two molecular clouds, namely the S235-Main and the S235-ABC, with $\sim$ 4 km s$^{-1}$ velocity separation. The bridge feature, the possible colliding interface and the complementary distribution of the two clouds are significant observational signatures of cloud-cloud collision in S235. The most direct evidence of cloud-cloud collision process in S235 is that the S235-Main (in a distance of 1547$^{+44}_{-43}$ pc) and S235-ABC (1567$^{+33}_{-39}$ pc) meet at almost the same position (within 1$\sigma$ error range) at a supersonic relative speed. We identified ten $^{13}$CO clumps from PMO-13.7m observations, 22 dust cores from the archival SCUBA-2 data, and 550 YSOs from NIR-MIR data. 63$\%$ of total YSOs are clustering in seven MST groups (M1$-$M7). The tight association between the YSO groups (M1 $\&$ M7) and the bridge feature suggests that the CCC process triggers star formation there. The collisional impact subregion (the South) shows $3\sim5$ times higher CFE and SFE (average value of 12.3$\%$ and 10.6$\%$, respectively) than the non-collisional impact subregion (2.4$\%$ and 2.6$\%$, respectively), suggesting that the CCC process may have enhanced the CFE and SFE of the clouds compared to those without collision influence.

Understanding the methodological robustness in identifying and quantifying high-redshift bars is essential for studying their evolution with the {\it James} {\it Webb} Space Telescope (JWST). Using a sample of nearby spiral galaxies, we created simulated images consistent with the observational conditions of the Cosmic Evolution Early Release Science (CEERS) survey. Through a comparison of measurements before and after image degradation, we show that the bar measurements for massive galaxies remain robust against noise. While the bar position angle measurement is unaffected by resolution, both the bar size ($a_{\rm bar}$) and bar ellipticity are typically underestimated, with the extent depending on $a_{\rm bar}/{\rm FWHM}$. To address these effects, correction functions are derived. We find that the detection rate of bars remains at $\sim$ 1 when the $a_{\rm bar}/{\rm FWHM}$ is above 2, below which the rate drops sharply, quantitatively validating the effectiveness of using $a_{\rm bar}>2\times {\rm FWHM}$ as a bar detection threshold. By holding the true bar fraction ($f_{\rm bar}$) constant and accounting for both resolution effects and intrinsic bar size growth, the simulated CEERS images yield an apparent F444W-band $f_{\rm bar}$ that decreases significantly with higher redshifts. Remarkably, this simulated apparent $f_{\rm bar}$ is in good agreement with JWST observations reported by Conte et al., suggesting that the observed $f_{\rm bar}$ is significantly underestimated, especially at higher redshifts, leading to an overstated evolution of the $f_{\rm bar}$. Our results underscore the importance of disentangling the true $f_{\rm bar}$ evolution from resolution effects and bar size growth.

A plethora of coronal models, from empirical to more complex magnetohydrodynamic (MHD) ones, are being used for reconstructing the coronal magnetic field topology and estimating the open magnetic flux. However, no individual solution fully agrees with coronal hole observations and in situ measurements of open flux at 1~AU, as there is a strong deficit between model and observations contributing to the known problem of the missing open flux. In this paper we investigate the possible origin of the discrepancy between modeled and observed magnetic field topology by assessing the effect on the simulation output by the choice of the input boundary conditions and the simulation set up, including the choice of numerical schemes and the parameter initialization. In the frame of this work, we considered four potential field source surface based models and one fully MHD model, different types of global magnetic field maps and model initiation parameters. After assessing the model outputs using a variety of metrics, we conclude that they are highly comparable regardless of the differences set at initiation. When comparing all models to coronal hole boundaries extracted by extreme ultraviolet (EUV) filtergrams we find that they do not compare well. This miss-match between observed and modeled regions of open field is a candidate contributing to the open flux problem.

The search for non-Gaussian signatures in the Cosmic Microwave Background (CMB) is crucial for understanding the physics of the early Universe. Given the possibility of non-Gaussian fluctuations in the CMB, a recent revision to the standard $\Lambda$-Cold Dark Matter ($\Lambda$CDM) model has been proposed, dubbed "Super-$\Lambda$CDM". This model introduces additional free parameters to account for the potential effects of a trispectrum in the primordial fluctuations. In this study, we explore the impact of the Super-$\Lambda$CDM model on current constraints on neutrino physics. In agreement with previous research, our analysis reveals that for most of the datasets, the Super-$\Lambda$CDM parameter $A_0$ significantly deviates from zero at over a $95\%$ confidence level. We then demonstrate that this signal might influence current constraints in the neutrino sector. Specifically, we find that the current constraints on neutrino masses may be relaxed by over a factor of two within the Super-$\Lambda$CDM framework, thanks to the correlation present with $A_0$. Consequently, locking $A_0=0$ might introduce a bias, leading to overly stringent constraints on the total neutrino mass.

We describe here updates and new elements of the Catalogue of Cometary Orbits and their Dynamical Evolution (CODE) that, in its original 2020 version, has been introduced by Kr\'olikowska & Dybczy\'nski (2020). Currently, the CODE Catalogue offers rich sets of orbital solutions for almost a complete sample of Oort spike comets discovered between 1900 and 2021. We often offer several orbital solutions based on different nongravitational force models or different observational material treatments. An important novelty is that the `previous` (at previous perihelion or at 120,000 au from the Sun in the past) and `next` (at next perihelion or 120,000 au after leaving the planetary zone) orbits are given in two variants. One with the dynamical model restricted only to the full Galactic tide (with all individual stars omitted) and the second one, where all currently known stellar perturbers are also taken into account. Calculations of the previous and next orbits were performed using the up-to-date StePPeD database of potential stellar perturbers.

We revisit the one-loop corrections on CMB scale perturbations induced from small scale modes in single field models which undergo a phase of ultra slow-roll inflation. There were concerns that large loop corrections are against the notion of the decoupling of scales and they are cancelled out once the boundary terms are included in Hamiltonian. We highlight that the non-linear coupling between the long and short modes and the modulation of the short mode power spectrum by the long mode are the key physical reasons behind the large loop corrections. In particular, in order for the modulation by the long mode to be significant there should be a strong scale-dependent enhancement in power spectrum of the short mode which is the hallmark of the USR inflation. We highlight the important roles played by the would-be decaying mode which were not taken into account properly in recent works claiming the loop cancellation. We confirm the original conclusion that the loop corrections are genuine and they can be dangerous for PBHs formation unless the transition to the final attractor phase is mild.

Large sky spectroscopic surveys have reached the scale of photometric surveys in terms of sample sizes and data complexity. These huge datasets require efficient, accurate, and flexible automated tools for data analysis and science exploitation. We present the Galaxy Spectra Network/GaSNet-II, a supervised multi-network deep learning tool for spectra classification and redshift prediction. GaSNet-II can be trained to identify a customized number of classes and optimize the redshift predictions for classified objects in each of them. It also provides redshift errors, using a network-of-networks that reproduces a Monte Carlo test on each spectrum, by randomizing their weight initialization. As a demonstration of the capability of the deep learning pipeline, we use 260k Sloan Digital Sky Survey spectra from Data Release 16, separated into 13 classes including 140k galactic, and 120k extragalactic objects. GaSNet-II achieves 92.4% average classification accuracy over the 13 classes (larger than 90% for the majority of them), and an average redshift error of approximately 0.23% for galaxies and 2.1% for quasars. We further train/test the same pipeline to classify spectra and predict redshifts for a sample of 200k 4MOST mock spectra and 21k publicly released DESI spectra. On 4MOST mock data, we reach 93.4% accuracy in 10-class classification and an average redshift error of 0.55% for galaxies and 0.3% for active galactic nuclei. On DESI data, we reach 96% accuracy in (star/galaxy/quasar only) classification and an average redshift error of 2.8% for galaxies and 4.8% for quasars, despite the small sample size available. GaSNet-II can process ~40k spectra in less than one minute, on a normal Desktop GPU. This makes the pipeline particularly suitable for real-time analyses of Stage-IV survey observations and an ideal tool for feedback loops aimed at night-by-night survey strategy optimization.

Using a fully Bayesian approach, Gaussian Process regression is extended to include marginalisation over the kernel choice and kernel hyperparameters. In addition, Bayesian model comparison via the evidence enables direct kernel comparison. The calculation of the joint posterior was implemented with a transdimensional sampler which simultaneously samples over the discrete kernel choice and their hyperparameters by embedding these in a higher-dimensional space, from which samples are taken using nested sampling. This method was explored on synthetic data from exoplanet transit light curve simulations. The true kernel was recovered in the low noise region while no kernel was preferred for larger noise. Furthermore, inference of the physical exoplanet hyperparameters was conducted. In the high noise region, either the bias in the posteriors was removed, the posteriors were broadened or the accuracy of the inference was increased. In addition, the uncertainty in mean function predictive distribution increased due to the uncertainty in the kernel choice. Subsequently, the method was extended to marginalisation over mean functions and noise models and applied to the inference of the present-day Hubble parameter, $H_0$, from real measurements of the Hubble parameter as a function of redshift, derived from the cosmologically model-independent cosmic chronometer and {\Lambda}CDM-dependent baryon acoustic oscillation observations. The inferred $H_0$ values from the cosmic chronometers, baryon acoustic oscillations and combined datasets are $H_0$ = 66$\pm$6 km/s/Mpc, $H_0$ = 67$\pm$10 km/s/Mpc and $H_0$ = 69$\pm$6 km/s/Mpc, respectively. The kernel posterior of the cosmic chronometers dataset prefers a non-stationary linear kernel. Finally, the datasets are shown to be not in tension with ln(R)=12.17$\pm$0.02.

Exploring planetary systems similar to our solar system can provide a means to explore a large range of possibly temperate climates on Earth-like worlds. Rather than run hundreds of simulations with different eccentricities at fixed obliquities, our variable-eccentricity approach provides a means to cover an incredibly large parameter space. Herein Jupiter's orbital radius is moved substantially inward in two different scenarios, causing a forcing on Earth's eccentricity. In one case, the eccentricity of Earth varies from 0 to 0.27 over ~7000 yr for three different fixed obliquities (0{\deg}, 23{\deg}, and 45{\deg}). In another case, the eccentricity varies from 0 to 0.53 over ~9400 yr in a single case with zero obliquity. In all cases, we find that the climate remains stable, but regional habitability changes through time in unique ways. At the same time, the moist greenhouse state is approached but only when at the highest eccentricities.

The cosmic magnification is able to probe the geometry of large scale structure on cosmological scales, thereby providing another window for probing theories of the late-time accelerated expansion of the Universe. It holds the potential to reveal new information on the nature of dark energy and modified gravity. By using the angular power spectrum, we investigated cosmic magnification in beyond-Horndeski gravity. We incorporated the known relativistic corrections and considered only large scales, where relativistic effects are known to become substantial. We probed both the total relativistic signal, and the individual relativistic signals. Our results suggest that surveys at low redshifts ($z \,{\lesssim}\, 0.5$) will be able to measure directly the total relativistic signal in the total magnification angular power spectrum, without the need for multi-tracer analysis (to beat down cosmic variance); similarly, for the Doppler signal, at the given $z$. However, for the integrated-Sachs-Wolfe, the time-delay, and the (gravitational) potential signals, respectively, it will require surveys at high redshifts ($z \,{\gtrsim}\, 3$). For both aforementioned sets of signals, their amplitudes at the given $z$ will ordinarily surpass cosmic variance, and hence, are able to be detected directly; whereas at other $z$, multi-tracer techniques will need to be taken into account. We also found that the beyond-Horndeski gravity boosts relativistic effects; consequently, the cosmic magnification. Conversely, relativistic effects enhance the potential of the total magnification angular power spectrum to detect the imprint of beyond-Horndeski gravity.

The fraction of massive stars in young stellar clusters is of importance as they are the dominant sources of both mechanical and radiative feedback, strongly influencing the thermal and dynamical state of their birth environments. It turns out that a significant fraction of massive stars escape from their parent cluster via dynamical interactions of single stars and/or multiple stellar systems. M 17 is the nearest giant H II region hosting a very young and massive cluster: NGC 6618. Our aim is to identify stars brighter than G < 21 mag that belong to NGC 6618, including the (massive) stars that may have escaped since its formation, and to determine the cluster distance and age. We identified 42 members of NGC 6618 of which eight have a spectral type of O, with a mean distance of 1675 pc and a transversal velocity dispersion of about 3 km/s , and a radial velocity dispersion of 6 km/s. Another ten O stars are associated with NGC 6618, but they cannot be classified as members due to poor astrometry or high extinction. We have also identified six O star runaways. The relative transverse velocity of these runaways ranges from 10 to 70 km/s and their kinematic age ranges from about 100 to 750 kyr. Given the already established young age of NGC 6618 (< 1 Myr), this implies that massive stars are being ejected from the cluster already directly after or during the cluster formation process. When constructing the initial mass function, one has to take into account the massive stars that have already escaped from the cluster, that is, about 30% of the O stars of the original population of NGC 6618. The trajectories of the O runaways can be traced back to the central 0.25 pc region of NGC 6618. The good agreement between the evolutionary and kinematic age of the runaways implies that the latter provides an independent way to estimate (a lower limit to) the age of the cluster.

Cloud-cloud collisions (CCCs) are expected to compress gas and trigger star formation. However, it is not well understood how the collisions and the induced star formation affect galactic-scale properties. By developing an on-the-fly algorithm to identify CCCs at each timestep in a galaxy simulation and a model that relates CCC-triggered star formation to collision speeds, we perform simulations of isolated galaxies to study the evolution of galaxies and giant molecular clouds (GMCs) with prescriptions of self-consistent CCC-driven star formation and stellar feedback. We find that the simulation with the CCC-triggered star formation produces slightly higher star formation rates and a steeper Kennicutt-Schmidt relation than that with a more standard star formation recipe, although collision speeds and frequencies are insensitive to the star formation models. In the simulation with the CCC model, about 70% of the stars are born via CCCs, and colliding GMCs with masses of $\approx 10^{5.5}\,M_{\odot}$ are the main drivers of CCC-driven star formation. In the simulation with the standard star formation recipe, about 50% of stars are born in colliding GMCs even without the CCC-triggered star formation model. These results suggest that CCCs may be one of the most important star formation processes in galaxy evolution. Furthermore, we find that a post-processing analysis of CCCs, as used in previous studies in galaxy simulations, may lead to slightly greater collision speeds and significantly lower collision frequencies than the on-the-fly analysis.

Radio emission from magnetars provides a unique probe of the relativistic, magnetized plasma within the near-field environment of these ultra-magnetic neutron stars. The transmitted waves can undergo birefringent and dispersive propagation effects that result in frequency-dependent conversions of linear to circularly polarized radiation and vice-versa, thus necessitating classification when relating the measured polarization to the intrinsic properties of neutron star and fast radio burst (FRB) emission sites. We report the detection of such behavior in 0.7-4 GHz observations of the P = 5.54 s radio magnetar XTE J1810$-$197 following its 2018 outburst. The phenomenon is restricted to a narrow range of pulse phase centered around the magnetic meridian. Its temporal evolution is closely coupled to large-scale variations in magnetic topology that originate from either plastic motion of an active region on the magnetar surface or free precession of the neutron star crust. Our model of the effect deviates from simple theoretical expectations for radio waves propagating through a magnetized plasma. Birefringent self-coupling between the transmitted wave modes, line-of-sight variations in the magnetic field direction and differences in particle charge or energy distributions above the magnetic pole are explored as possible explanations. We discuss potential links between the immediate magneto-ionic environments of magnetars and those of FRB progenitors.

We present a theoretical model of the near-surface shear layer (NSSL) of the Sun. Convection cells deeper down are affected by the Sun's rotation, but this is not the case in a layer just below the solar surface due to the smallness of the convection cells there. Based on this idea, we show that the thermal wind balance equation (the basic equation in the theory of the meridional circulation which holds inside the convection zone) can be solved to obtain the structure of the NSSL, matching observational data remarkably well.

We present a first measurement of the galaxy-galaxy-CMB lensing bispectrum. The signal is detected at $26\sigma$ and $22\sigma$ significance using two samples from the unWISE galaxy catalog at mean redshifts $\bar{z}=0.6$ and $1.1$ and lensing reconstructions from Planck PR4. We employ a compressed bispectrum estimator based on the cross-correlation between the square of the galaxy overdensity field and CMB lensing reconstructions. We present a series of consistency tests to ensure the cosmological origin of our signal and rule out potential foreground contamination. We compare our results to model predictions from a halo model previously fit to only two-point spectra, finding reasonable agreement when restricting our analysis to large scales. Such measurements of the CMB lensing galaxy bispectrum will have several important cosmological applications, including constraining the uncertain higher-order bias parameters that currently limit lensing cross-correlation analyses.

We present a new method for obtaining photometric redshifts (photo-z) for sources observed by multiple photometric surveys using a combination (conflation) of the redshift probability distributions (PDZs) obtained independently from each survey. The conflation of the PDZs has several advantages over the usual method of modelling all the photometry together, including modularity, speed, and accuracy of the results. Using a sample of galaxies with narrow-band photometry in 56 bands from J-PAS and deeper grizy photometry from the Hyper-SuprimeCam Subaru Strategic program (HSC-SSP), we show that PDZ conflation significantly improves photo-z accuracy compared to fitting all the photometry or using a weighted average of point estimates. The improvement over J-PAS alone is particularly strong for i>22 sources, which have low signal-to-noise ratio in the J-PAS bands. For the entire i<22.5 sample, we obtain a 64% (45%) increase in the number of sources with redshift errors |Dz|<0.003, a factor 3.3 (1.9) decrease in the normalised median absolute deviation of the errors (sigma_NMAD), and a factor 3.2 (1.3) decrease in the outlier rate compared to J-PAS (HSC-SSP) alone. The photo-z accuracy gains from combining the PDZs of J-PAS with a deeper broadband survey such as HSC-SSP are equivalent to increasing the depth of J-PAS observations by ~1.2--1.5 magnitudes. These results demonstrate the potential of PDZ conflation and highlight the importance of including the full PDZs in photo-z catalogues.

We perform a calculation of dense and hot nuclear matter where the mean interaction between nucleons is described by in-medium effective fields and where we employ analytical approximations of the Fermi integrals. We generalize a previous work [1], where we have addressed the case of the Fermi gas model with in-medium effective mass. In the present work, we fully treat the in-medium interaction by considering both its contribution to the in-medium effective fields, which can be subsumed by the mass in some cases, and to the potential term. Our formalism is general and could be applied to relativistic and non-relativistic approaches. It is illustrated for different popular models -- Skyrme, nonlinear, and density-dependent relativistic mean-field models -- and it provides a clear understanding of the in-medium correction to the pressure, which is present in the case of the Skyrme models but is not for the relativistic ones. For the Fermi integrals, we compare the analytical approximation to the, so-called, ``exact'' numerical calculations in order to quantitatively estimate the accuracy of the approximation.

Boson stars arise as solutions of a massive complex scalar field coupled to gravity. A variety of scalar potentials, giving rise to different types of boson stars, have been studied in the literature. Here we study instead the effect of promoting the kinetic term of the scalar field to a nonlinear sigma model -- an extension that is naturally motivated by UV completions of gravity like string theory. We consider the $\mathrm{O}(3)$ and $\mathrm{SL}(2,\mathbb{R})$ sigma models with minimally interacting potentials and obtain their boson star solutions. We study the maximum mass and compactness of the solutions as a function of the curvature of the sigma model and compare the results to the prototypical case of mini boson stars, which are recovered in the case of vanishing curvature. The effect of the curvature turns out to be dramatic. While $\mathrm{O}(3)$ stars are massive and can reach a size as compact as $R\sim 3.3 GM$, $\mathrm{SL}(2,\mathbb{R})$ stars are much more diffuse and only astrophysically viable if the bosons are ultralight. These results show that the scalar kinetic term is at least as important as the potential in determining the properties of boson stars.

The subtle influence of gravitational waves on the apparent positioning of celestial bodies offers novel observational windows. We calculate the expected astrometric signal induced by an isotropic Stochastic Gravitational Wave Background (SGWB) in the short distance limit. Our focus is on the resultant proper motion of Solar System objects, a signal on the same time scales addressed by Pulsar Timing Arrays (PTA). We derive the corresponding astrometric deflection patterns, finding that they manifest as distinctive dipole and quadrupole correlations, or in some cases, may not be present. Our analysis encompasses both Einsteinian and non-Einsteinian polarisations. We estimate the upper limits for the amplitude of a scale-invariant SGWB that could be obtained by tracking the proper motions of large numbers of solar system objects such as asteroids. With the Gaia satellite and the Vera C. Rubin Observatory poised to track an extensive sample of asteroids-ranging from $O(10^5)$ to $O(10^6)$, we highlight the significant future potential for similar surveys to contribute to our understanding of the SGWB.

We explore the cosmic birefringence signal produced by an ultralight axion field with a small CP-violating coupling to bulk SM matter in addition to the usual CP-preserving photon coupling. The change in the vacuum expectation value of the field between recombination and today results in a frequency-independent rotation of the plane of CMB linear polarization across the entire sky. While many previous approaches rely on the axion rolling from a large initial expectation value, the couplings considered in this work robustly generate the birefringence signal regardless of initial conditions, by sourcing the field from the cosmological nucleon density. We place bounds on such monopole-dipole interactions using measurements of the birefringence angle from Planck and WMAP data, which improve upon existing constraints by up to three orders of magnitude. We also discuss UV completions of this model, and possible strategies to avoid fine-tuning the axion mass.

Black hole solutions in the braneworld scenario are predicted to possess a tidal charge parameter, leaving imprints in the quasinormal spectrum. We conduct an extensive computation of such spectrum, and use it to construct a waveform model for the ringdown relaxation regime of binary black hole mergers observed by LIGO and Virgo. Applying a Bayesian time-domain analysis formalism, we analyse a selected dataset from the GWTC-3 LIGO-Virgo-Kagra catalog of binary coalescences, bounding the value of the tidal charge. With our analysis we obtain the first robust constraints on such charges, highlighting the importance of accounting for the previously ignored correlations with the other black hole intrinsic parameters.

Tests of general relativity with gravitational wave observations from merging compact binaries continue to confirm Einstein's theory of gravity with increasing precision. However, these tests have so far only been applied to signals that were first confidently detected by matched-filter searches assuming general relativity templates. This raises the question of selection biases: what is the largest deviation from general relativity that current searches can detect, and are current constraints on such deviations necessarily narrow because they are based on signals that were detected by templated searches in the first place? In this paper, we estimate the impact of selection effects for tests of the inspiral phase evolution of compact binary signals with a simplified version of the GstLAL search pipeline. We find that selection biases affect the search for very large values of the deviation parameters, much larger than the constraints implied by the detected signals. Therefore, combined population constraints from confidently detected events are mostly unaffected by selection biases, with the largest effect being a broadening at the $\sim10$ % level for the $-1$PN term. These findings suggest that current population constraints on the inspiral phase are robust without factoring in selection biases. Our study does not rule out a disjoint, undetectable binary population with large deviations from general relativity, or stronger selection effects in other tests or search procedures.

In view of recent interest in high-frequency detectors, broad features of gravitational wave signals from phase transitions taking place soon after inflation are summarized. The influence of the matter domination era that follows the slow-roll stage is quantified in terms of two equilibration rates. Turning to the highest-frequency part of the spectrum, we show how it is constrained by the fact that the bubble distance scale must exceed the mean free path.

The neutrino magnetic moment operator clasps a tiny but non-zero value within the standard model (SM) of particle physics and rather enhanced values in various new physics models. This generation of the magnetic moment ($\mu_\nu$) is through quantum loop corrections which can exhibit spin-flavor oscillations in the presence of an external magnetic field. Also, several studies predict the existence of a primordial magnetic field (PMF) in the early universe, extending back to the era of Big Bang Nucleosynthesis (BBN) and before. The recent NANOGrav measurement can be considered as a strong indication of the presence of these PMFs. In this work, we consider the effect of the PMF on the flux of relic neutrinos. For Dirac neutrinos, we show that half of the active relic neutrinos can become sterile due to spin-flavor oscillations well before becoming non-relativistic owing to the expansion of the Universe and also before the timeline of the formation of galaxies and hence intergalactic fields, subject to the constraints on the combined value of $\mu_\nu$ and the cosmic magnetic field at the time of neutrino decoupling. For the upper limit of PMF allowed by the BBN, this can be true even if the experimental bounds on $\mu_{\nu}$ approaches a few times its SM value.

The $\mathrm{^{20}Ne(p, \gamma)^{21}Na}$ reaction is the slowest in the NeNa cycle and directly affects the abundances of the Ne and Na isotopes in a variety of astrophysical sites. Here we report the measurement of its direct capture contribution, for the first time below $E\rm_{cm} = 352$~keV, and of the contribution from the $E^{\rm }_{cm} = 368$~keV resonance, which dominates the reaction rate at $T=0.03-1.00$~GK. The experiment was performed deep underground at the Laboratory for Underground Nuclear Astrophysics, using a high-intensity proton beam and a windowless neon gas target. Prompt $\gamma$ rays from the reaction were detected with two high-purity germanium detectors. We obtain a resonance strength $\omega \gamma~=~(0.112 \pm 0.002_{\rm stat}~\pm~0.005_{\rm sys})$~meV, with an uncertainty a factor of $3$ smaller than previous values. Our revised reaction rate is 20\% lower than previously adopted at $T < 0.1$~GK and agrees with previous estimates at temperatures $T \geq 0.1$~GK. Initial astrophysical implications are presented.

We investigate the enhancement of the power spectra in models with multiple scalar fields large enough to produce primordial black holes. We derive the criteria that can lead to an exponential amplification of the curvature perturbation on subhorizon scales, while leaving the perturbations stable on superhorizon scales. We apply our results on the three-field ultra-light scenario and show how the presence of extra turning parameters in the field space can yield distinct observables compared to two fields. Finally, we present analytic solutions for both sharp and broad turns, and clarify the role of the Hubble friction that has been overlooked previously.

In this Letter we discuss the intrinsic pathologies associated to theories formulated in the framework of symmetric teleparallel geometries and argue how they are prone to propagating Ostrogradski ghosts. We illustrate our general argument by working out the cosmological perturbations in $f(\mathbb{Q})$ theories. We focus on the three branches of spatially flat cosmologies and show that they are all pathological. Two of these branches exhibit reduced linear spectra, signalling that they are infinitely strongly coupled. For the remaining branch we unveil the presence of seven propagating modes associated to the gravitational sector and we show that at least one of them is a ghost. Our results show the non-viability of these cosmologies and sheds light on the number of propagating degrees of freedom in these theories.