Papers for Wednesday, Jan 25 2023

The inner solar system's modern orbital architecture provides inferences into the epoch of terrestrial planet formation; a ~100 Myr time period of planet growth via collisions with planetesimals and other proto-planets. While classic numerical simulations of this scenario adequately reproduced the correct number of terrestrial worlds, their semi-major axes and approximate formation timescales, they struggled to replicate the Earth-Mars and Venus-Mercury mass ratios. In a series of past independent investigations, we demonstrated that Mars' mass is possibly the result of Jupiter and Saturn's early orbital evolution, while Mercury's diminutive size might be the consequence of a primordial mass deficit in the region. Here, we combine these ideas in a single modeled scenario designed to simultaneously reproduce the formation of all four terrestrial planets and the modern orbits of the giant planets in broad strokes. By evaluating our Mercury analogs' core mass fractions, masses, and orbital offsets from Venus, we favor a scenario where Mercury forms through a series of violent erosive collisions between a number of ~Mercury-mass embryos in the inner part of the terrestrial disk. We also compare cases where the gas giants begin the simulation locked in a compact 3:2 resonant configuration to a more relaxed 2:1 orientation and find the former to be more successful. In 2:1 cases, the entire Mercury-forming region is often depleted due to strong sweeping secular resonances that also tend to overly excite the orbits of Earth and Venus as they grow. While our model is quite successful at replicating Mercury's massive core and dynamically isolated orbit, the planets' low mass remains extremely challenging to match. Finally, we discuss the merits and drawbacks of alternative evolutionary scenarios and initial disk conditions.

Contamination from galaxy fragments, identified as sources, is a major issue in large photometric galaxy catalogs. In this paper, we prove that this problem can be easily addressed with computer vision techniques. We use image cutouts to train a convolutional neural network (CNN) to identify catalogued sources that are in reality just star formation regions and/or shreds of larger galaxies. The CNN reaches an accuracy ~98% on our testing datasets. We apply this CNN to galaxy catalogs from three amongst the largest surveys available today: the Sloan Digital Sky Survey (SDSS), the DESI Legacy Imaging Surveys and the Panoramic Survey Telescope and Rapid Response System Survey (Pan-STARSS). We find that, even when strict selection criteria are used, all catalogs still show a ~5% level of contamination from galaxy shreds. Our CNN gives a simple yet effective solution to clean galaxy catalogs from these contaminants.

Galaxy evolution can be dramatically affected by the environment, especially by the dense environment of a galaxy cluster. Recent observational studies show that massive galaxies undergoing strong ram pressure stripping (RPS) also show an enhanced frequency of nuclear activity. Here, we investigate this topic using a suite of wind-tunnel hydrodynamical simulations of an individual massive $M_\text{star} = 10^{11} M_\odot$ disk galaxy with 39 pc resolution and including star formation and stellar feedback. We find that RPS increases the inflow of gas to the galaxy centre regardless of the wind impact angle. This increase is driven by the mixing of interstellar and non-rotating intracluster media at all wind angles, and by increased torque on the inner disk gas, mainly from local pressure gradients when the ICM wind has an edge-on component. In turn, the increase in pressure torques is driven by rising gradient of ram pressure. We estimate the black hole (BH) accretion using Bondi-Hoyle and torque models, and compare it with the mass flux in the central 140 pc region. We find that the torque model estimates much less accretion onto the BH of a RPS galaxy than the Bondi-Hoyle estimator. However, we argue that both models are incomplete because the commonly used torque model does not account for torques caused by the gas distribution or local pressure gradients and the Bondi-Hoyle estimator depends on the the sound speed of the hot gas, which includes the ICM in stripped galaxies, thus a new estimator would be required.

We derived stellar ages and metallicities [Z/H] for $\sim$70 passive early type galaxies (ETGs) selected from VANDELS survey over the redshift range 1.0$<$$z$$<$1.4 and stellar mass range 10$<$log(M$_*$/M$_\odot$)$<$11.6. We find significant systematics in their estimates depending on models and wavelength ranges considered. Using the full-spectrum fitting technique, we find that both [Z/H] and age increase with mass as for local ETGs. Age and metallicity sensitive spectral indices independently confirm these trends. According to EMILES models, for 67 per cent of the galaxies we find [Z/H]$>$0.0, a percentage which rises to $\sim$90 per cent for log(M$_*$/M$_\odot$)$>$11 where the mean metallicity is [Z/H]=0.17$\pm$0.1. A comparison with homogeneous measurements at similar and lower redshift does not show any metallicity evolution over the redshift range 0.0<z<1.4. The derived star formation (SF) histories show that the stellar mass fraction formed at early epoch increases with the mass of the galaxy. Galaxies with log(M$_*$/M$_\odot$)$>$11.0 host stellar populations with [Z/H]>0.05, formed over short timescales ($\Delta{t50}$$<$1 Gyr) at early epochs (t$_{form}$$<$2 Gyr), implying high star formation rates (SFR$>$100 M$_\odot$/yr) in high mass density regions (log($\Sigma_{1kpc}$)$>$10 M$_\odot$/kpc$^2$). This sharp picture tends to blur at lower masses: log(M$_*$/M$_\odot$)$\sim$10.6 galaxies can host either old stars with [Z/H]$<$0.0 or younger stars with [Z/H]$>$0.0, depending on the duration ($\Delta{t50}$) of the SF. The relations between galaxy mass, age and metallicities are therefore largely set up ab initio as part of the galaxy formation process. Mass, SFR and SF time-scale all contribute to shape up the stellar mass-metallicity relation with the mass that modulates metals retention.

Results obtained from an analysis of the energy spectrum of cosmic rays with energies in the region of $E_0 \ge 10^{17}$ eV over the period of continuous observations from 1974 to 2017 are presented. A refined expression for estimating the primary-particle energy is used for individual events. This expression is derived from calculations aimed at determining the responses of the ground-based and underground scintillation detectors of the Yakutsk array for studying extensive air showers (EAS) and performed within the QGSJET01, QGSJET-II-04, SIBYLL-2.1, and EPOS-LHC models by employing the CORSIKA code package. The new estimate of $E_0$ is substantially lower than its counterpart used earlier.

Large-scale cosmological simulations are an indispensable tool for modern cosmology. To enable model-space exploration, fast and accurate predictions are critical. In this paper, we show that the performance of such simulations can be further improved with time-stepping schemes that use input from cosmological perturbation theory. Specifically, we introduce a class of time-stepping schemes derived by matching the particle trajectories in a single leapfrog/Verlet drift-kick-drift step to those predicted by Lagrangian perturbation theory (LPT). As a corollary, these schemes exactly yield the analytic Zel'dovich solution in 1D in the pre-shell-crossing regime (i.e. before particle trajectories cross). One representative of this class is the popular FastPM scheme by Feng et al. 2016, which we take as our baseline. We then construct more powerful LPT-inspired integrators and show that they outperform FastPM and standard integrators in fast simulations in two and three dimensions with $\mathcal{O}(1 - 100)$ timesteps, requiring less steps to accurately reproduce the power spectrum and bispectrum of the density field. Furthermore, we demonstrate analytically and numerically that, for any integrator, higher-order convergence cannot be achieved in the post-shell-crossing regime, owing to the lacking regularity of the acceleration field. Also, we study the impact of the timestep spacing and of a decaying mode present in the initial conditions. Importantly, we find that symplecticity of the integrator plays a minor role for fast approximate simulations with a small number of timesteps.

(Abridged) Galaxy clusters are a powerful probe of cosmological models. Next generation large-scale optical and infrared surveys will reach unprecedented depths over large areas and require highly complete and pure cluster catalogs, with a well defined selection function. We have developed a new cluster detection algorithm YOLO-CL, which is a modified version of the state-of-the-art object detection deep convolutional network YOLO, optimized for the detection of galaxy clusters. We trained YOLO-CL on color images of the redMaPPer cluster detections in the SDSS. We find that YOLO-CL detects $95-98\%$ of the redMaPPer clusters, with a purity of $95-98\%$ calculated by applying the network to SDSS blank fields. When compared to the MCXC2021 X-ray catalog in the SDSS footprint,YOLO-CL is more complete then redMaPPer, which means that the neural network improved the cluster detection efficiency of its training sample. The YOLO-CL selection function is approximately constant with redshift, with respect to the MCXC2021 cluster mean X-ray surface brightness. YOLO-CL shows high performance when compared to traditional detection algorithms applied to SDSS. Deep learning networks benefit from a strong advantage over traditional galaxy cluster detection techniques because they do not need galaxy photometric and photometric redshift catalogs. This eliminates systematic uncertainties that can be introduced during source detection, and photometry and photometric redshift measurements. Our results show that YOLO-CL is an efficient alternative to traditional cluster detection methods. In general, this work shows that it is worth exploring the performance of deep convolution networks for future cosmological cluster surveys, such as the Rubin/LSST, Euclid or the Roman Space Telescope surveys.

We present new ALMA Band 8 (rest-frame $90\,\mu$m) observations of three massive ($M_\star \approx 10^{10}\,M_\odot$) galaxies at $z\approx7$ previously detected in [CII]$158\,\mu$m and underlying dust continuum emission in the Reionization Era Bright Emission Line Survey (REBELS). We detect the dust continuum emission of two of our targets in Band 8 (REBELS-25 and REBELS-38), while REBELS-12 remains undetected. Through modified blackbody fitting we determine cold dust temperatures ($T_\mathrm{dust} \approx 30 - 35\,$K) in both of the dual-band detected targets, given a fiducial model of optically thin emission with $\beta = 2.0$. Their dust temperatures are lower than most $z\sim7$ galaxies in the literature, and consequently their dust masses are higher ($M_\mathrm{dust} \approx 10^{8}\,M_\odot$). Nevertheless, these large dust masses are still consistent with predictions from models of dust production in the early Universe. In addition, we target and detect [OIII]$88\,\mu$m emission in both REBELS-12 and REBELS-25, and find $L_\mathrm{[OIII]} / L_\mathrm{[CII]}$ ratios of approximately unity, low compared to the $L_\mathrm{[OIII]} / L_\mathrm{[CII]} \gtrsim 2 - 10$ observed in the known $z\gtrsim6$ population thus far. We argue the lower line ratios are due to a comparatively weaker ionizing radiation field resulting from the less starbursty nature of our targets. This low burstiness supports the cold dust temperatures and below average $\mathrm{[OIII]}\lambda\lambda4959,5007 + \mathrm{H}\beta$ equivalent widths of REBELS-25 and REBELS-38, compared to the known high-redshift population. Overall, this provides evidence for the existence of a massive, dust-rich galaxy population at $z\approx7$ which has previously experienced vigorous star formation, but is currently forming stars in a steady, as opposed to bursty, manner.

Next generation aperture arrays are expected to consist of hundreds to thousands of antenna elements with substantial digital signal processing to handle large operating bandwidths of a few tens to hundreds of MHz. Conventionally, FX~correlators are used as the primary signal processing unit of the interferometer. These correlators have computational costs that scale as $\mathcal{O}(N^2)$ for large arrays. An alternative imaging approach is implemented in the E-field Parallel Imaging Correlator (EPIC) that was recently deployed on the Long Wavelength Array station at the Sevilleta National Wildlife Refuge (LWA-SV) in New Mexico. EPIC uses a novel architecture that produces electric field or intensity images of the sky at the angular resolution of the array with full or partial polarization and the full spectral resolution of the channelizer. By eliminating the intermediate cross-correlation data products, the computational costs can be significantly lowered in comparison to a conventional FX~or XF~correlator from $\mathcal{O}(N^2)$ to $\mathcal{O}(N \log N)$ for dense (but otherwise arbitrary) array layouts. EPIC can also lower the output data rates by directly yielding polarimetric image products for science analysis. We have optimized EPIC and have now commissioned it at LWA-SV as a commensal all-sky imaging back-end that can potentially detect and localize sources of impulsive radio emission on millisecond timescales. In this article, we review the architecture of EPIC, describe code optimizations that improve performance, and present initial validations from commissioning observations. Comparisons between EPIC measurements and simultaneous beam-formed observations of bright sources show spectral-temporal structures in good agreement.

White dwarf photospheric parameters are usually obtained by means of spectroscopic or photometric analysis. These results are not always consistent with each other, with the published values often including just the statistical uncertainties. The differences are more dramatic for white dwarfs with helium-dominated photospheres, so to obtain realistic uncertainties we have analysed a sample of 13 of these white dwarfs, applying both techniques to up to three different spectroscopic and photometric data sets for each star. We found mean standard deviations of < $\sigma T_{\mathrm{eff}}$ > = 524 K, < $\sigma \log g$ > = 0.27 dex and < $\sigma \log(\mathrm{H/He})$ > = 0.31 dex for the effective temperature, surface gravity and relative hydrogen abundance, respectively, when modelling diverse spectroscopic data. The photometric fits provided mean standard deviations up to < $\sigma T_{\mathrm{eff}}$ > = 1210 K and < $\sigma \log g$ > = 0.13 dex. We suggest these values to be adopted as realistic lower limits to the published uncertainties in parameters derived from spectroscopic and photometric fits for white dwarfs with similar characteristics. In addition, we investigate the effect of fitting the observational data adopting three different photospheric chemical compositions. In general, pure helium model spectra result in larger $T_{\mathrm{eff}}$ compared to those derived from models with traces of hydrogen. The $\log g$ shows opposite trends: smaller spectroscopic values and larger photometric ones when compared to models with hydrogen. The addition of metals to the models also affects the derived atmospheric parameters, but a clear trend is not found.

A model for the transport of anisotropic turbulence in an accretion disk is presented. This model is based on the mean field approximation and is designed to study turbulence of various nature and its role in the redistribution of the angular momentum of the accretion disk. The mean field approach makes it possible to take into account various types of instabilities by adding appropriate sources in the form of moments of fluctuations of hydrodynamic quantities. We used the model to study the role of convective instability in a gaseous and dusty circumstellar disk in the framework of a one-dimensional approximation. To do this, it was combined with the calculation of radiative transfer and with the calculation of the convective flow in the mixing length theory approximation. Within this framework, we confirm the conclusions of other authors that the turbulence generated by convection does not provide the observable disk accretion rates and sufficient heat source for which convection would be self-sustaining. The reasons for this are the strong anisotropy of turbulence in the disk, as well as the fact that convection turns out to be too weak source for turbulence.

Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT + HERMES-TP/SP nano-satellite constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP. In this work we simulate the improvement to the localisation capabilities of the HERMES-TP/SP when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6$^\circ$) to the HERMES orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, the combined constellation is capable of localising 60% of long GRBs to within ~ 30 deg$^2$ on the sky, and 60% of short GRBs within ~ 1850 deg$^2$. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi GBM. Further improvements by a factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit, which would both increase the fraction of sky covered by multiple satellite elements, and enable $\geq$ 60% of long GRBs to be localised within a radius of ~ 1.5$^\circ$ on the sky.

The Hubble constant $H_0$ is the value of the cosmic expansion rate at one time (the present), and cannot be adjusted successfully without taking into account the entire expansion history and cosmology. We outline some conditions, that if not quite ``no go'' are ``no thanks'', showing that changing the expansion history, e.g. employing dynamical dark energy, cannot reconcile disparate deductions of $H_0$ without upsetting some other cosmological measurement.

The heating of ions and electrons due to turbulent dissipation plays a crucial role in the thermodynamics of the solar wind and other plasma environments. Using magnetic field and thermal plasma observations from the first two perihelia of the Parker Solar Probe (PSP), we model the relative heating rates as a function of radial distance, magnetic spectra, and plasma conditions, enabling us to better characterize the thermodynamics of the inner heliosphere. We employ the Howes et al. 2008 steady-state cascade model, which considers the behavior of turbulent, low-frequency, wavevector-anisotropic, critically balanced Alfv\'enic fluctuations that dissipate via Landau damping to determine proton-to-electron heating rates $Q_p/Q_e$. We distinguish ion-cyclotron frequency circularly polarized waves from low-frequency turbulence and constrain the cascade model using spectra constructed from the latter. We find that the model accurately describes the observed energy spectrum from over 39.4 percent of the intervals from Encounters 1 and 2, indicating the possibility for Landau damping to heat the young solar wind. The ability of the model to describe the observed turbulent spectra increases with the ratio of thermal-to-magnetic pressure, $\beta_p$, indicating that the model contains the necessary physics at higher $\beta_p$. We estimate high magnitudes for the Kolmogorov constant which is inversely proportional to the non-linear energy cascade rate. We verify the expected strong dependency of $Q_p/Q_e$ on $\beta_p$ and the consistency of the critical balance assumption.

We present a comprehensive examination of interstellar P and Cl abundances based on an analysis of archival spectra acquired with the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer. Column densities of P II, Cl I, and Cl II are determined for a combined sample of 107 sight lines probing diffuse atomic and molecular gas in the local Galactic interstellar medium (ISM). We reevaluate the nearly linear relationship between the column densities of Cl I and H$_2$, which arises from the rapid conversion of Cl$^+$ to Cl$^0$ in regions where H$_2$ is abundant. Using the observed total gas-phase P and Cl abundances, we derive depletion parameters for these elements, adopting the methodology of Jenkins. We find that both P and Cl are essentially undepleted along sight lines showing the lowest overall depletions. Increasingly severe depletions of P are seen along molecule-rich sight lines. In contrast, gas-phase Cl abundances show no systematic variation with molecular hydrogen fraction. However, enhanced Cl (and P) depletion rates are found for a subset of sight lines showing elevated levels of Cl ionization. An analysis of neutral chlorine fractions yields estimates for the amount of atomic hydrogen associated with the H$_2$-bearing gas in each direction. These results indicate that the molecular fraction in the H$_2$-bearing gas is at least 10% for all sight lines with $\log N({\rm H}_2)\gtrsim18$ and that the gas is essentially fully molecular at $\log N({\rm H}_2)\approx21$.

Luminous quasars are powerful targets to investigate the role of feedback from supermassive black-holes (BHs) in regulating the growth phases of BHs themselves and of their host galaxies, up to the highest redshifts. Here we investigate the cosmic evolution of the occurrence and kinematics of BH-driven outflows, as traced by broad absorption line (BAL) features, due to the C IV ionic transition. We exploit a sample of 1935 quasars quasars at $z=2.1-6.6$ with bolometric luminosity log($L_{\rm bol}/$erg s$^{-1})\gtrsim46.8$, drawn from the Sloan Digital Sky Survey and from the X-shooter legacy survey of Quasars at Reionisation (XQR-30). We consider rest-frame optical bright quasars to minimise observational biases due to quasar selection criteria and we apply a homogeneous BAL identifiation analysis, based on employing composite template spectra to estimate the quasar intrinsic emission. We find a BAL quasar fraction close to 20\% at $z\sim2-4$, while it increases to almost 50\% at $z\sim6$. The velocity and width of the BAL features also increase at $z\gtrsim4.5$. We exclude that the redshift evolution of the BAL properties is due to differences in terms of quasar luminosity and accretion rate. These results suggest significant BH feedback occurring in the 1 Gyr old Universe, likely affecting the growth of BHs and, possibly, of their host galaxies, as supported by models of early BH and galaxy evolution.

The PASSAGES ($Planck$ All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts) collaboration has recently defined a sample of 30 gravitationally-lensed dusty star-forming galaxies (DSFGs). These rare, submillimeter-selected objects enable high-resolution views of the most extreme sites of star formation in galaxies at Cosmic Noon. Here, we present the first major compilation of strong lensing analyses using LENSTOOL for PASSAGES, including 15 objects spanning $z=1.1-3.3$, using complementary information from $0.6^{\prime\prime}$-resolution 1 mm Atacama Large Millimeter/submillimeter Array (ALMA) and $0.4^{\prime\prime}$ 5 cm Jansky Very Large Array continuum imaging, in tandem with 1.6$\mu$m $Hubble$ and optical imaging with Gemini-S. Magnifications range from $\mu = 2 - 28$ (median $\mu=7$), yielding intrinsic infrared luminosities of $L_{\rm IR} = 0.2 - 5.9 \times 10^{13}~L_\odot$ (median ${1.4}\times 10^{13}~L_\odot$) and inferred star formation rates of $170-6300~M_\odot~{\rm yr}^{-1}$ (median $1500~M_\odot~{\rm yr}^{-1}$). These results suggest that the PASSAGES objects comprise some of the most extreme known starbursts, rivaling the luminosities of even the brightest unlensed objects, further amplified by lensing. The intrinsic sizes of far-infrared continuum regions are large ($R_{\rm e} = {1.7 - 4.3}$ kpc; median $3.0$ kpc) but consistent with $L_{\rm IR}-R_{\rm e}$ scaling relations for $z>1$ DSFGs, suggesting a widespread spatial distribution of star formation. With modestly-high angular resolution, we explore if these objects might be maximal starbursts. Instead of approaching Eddington-limited surface densities, above which radiation pressure will disrupt further star formation, they are safely sub-Eddington -- at least on global, galaxy-integrated scales.

The fact that the O-type close binary star system AO~Cassiopeiae exhibits variable phase-locked linear polarization has been known since the mid-1970s. In this work, we re-observe the polarization arising from this system more than 50 years later to better estimate the interstellar polarization and to independently derive the orbital parameters, such as inclination, $i$, orientation, $\Omega$, and the direction of the rotation for the inner orbit from the phase-folded polarization curves of the Stokes $q$ and $u$ parameters. The Dipol-2 polarimeter was used to obtain linear polarization measurements of AO~Cassiopeiae in the $B$, $V$, and $R$ passbands with the T60 remotely controlled telescope at an unprecedented accuracy level of $\sim$0.003\%. We have obtained the first proper quantification of the interstellar polarization in the direction heading towards AO~Cas by observing the polarization of three neighboring field stars. We employed a Lomb-Scargle algorithm and detected a clear periodic signal for the orbital period of AO~Cas. The standard analytical method based on a two-harmonics Fourier fit was used to obtain the inclination and orientation of the binary orbit. Our polarimetric data exhibited an unambiguous periodic signal at 1.76 days, thus confirming the orbital period of the binary system of 3.52 days. Most of the observed polarization is of interstellar origin. The de-biased values of the orbital inclination are $i = 63^{\circ} +2^{\circ}/ -3^{\circ}$ and orientation of $\Omega = 29^{\circ} (209^{\circ}) \pm 8^{\circ}$. The direction of the binary system rotation on the plane of the sky is clockwise.

On large cosmological scales, anisotropic gravitational collapse is manifest in the dark cosmic web. Its statistical properties are well known for the standard $\Lambda$CDM cosmology, yet become modified for alternative dark matter models such as fuzzy dark matter (FDM). In this work, we assess for the first time the relative importance of cosmic nodes, filaments, walls and voids in a cosmology with small-scale suppression of power such as FDM. By applying the NEXUS+ Multiscale Morphology Filter technique to cosmological $N$-body simulations of FDM-like cosmologies, we quantify the mass and volume filling fractions of cosmic environments at redshifts $z\sim 3.4-5.6$ and find that 2D cosmic sheets host a larger share of the matter content of the Universe ($\sim 5$% increase for the $m=7 \times 10^{-22}$ eV model compared to CDM) as the particle mass $m$ is reduced. We find that the suppression of node-, filament-, wall- and void-conditioned halo mass functions at the low-mass end can occur well above the half-mode mass $M_{1/2}$. We show that log overdensity PDFs are more peaked in FDM-like cosmologies with medians shifted to higher values, a result of the suppression of the low overdensity tail as $m$ is reduced. Skewness estimates $S_3$ of the unconditioned overdensity PDF $P(\delta)$ in FDM-like cosmologies are systematically higher than in CDM, more so at high redshift $z\sim 5.5$ where the $m=10^{-22}$ eV model differs from CDM by $\sim 2 \sigma$. Accordingly, we advocate for the usage of $P(\delta)$ as a testbed for constraining FDM and other alternative dark matter models.

Solitons are observed to form in simulations of dark matter (DM) halos consisting of bosonic fields. We use the extended Press-Schechter formalism to compute the mass function of solitons, assuming various forms for the relationship between halo mass and soliton mass. We further provide a new calculation of the rate of soliton major mergers. Solitons composed of axion DM are unstable above a critical mass, and decay to either relativistic axions or photons, depending on the values of the coupling constants. We use the computed soliton major merger rate to predict the enhanced DM decay rate due to soliton instability. For certain values of currently allowed axion parameters, the energy injection into the intergalactic medium from soliton decays to photons is comparable to or larger than the energy injection due to core collapse supernovae at $z>10$. A companion paper explores the phenomenology of such an energy injection.

Hub-filament systems (HFSs) are potential sites of formation of star clusters and high mass stars. To understand the HFSs and to provide observational constraints on current theories that attempt to explainstar formation globally, we report a study of the region associated with G326.27-0.49 using infrared data of dust continuum and newly obtained observations on molecular tracers using the APEX telescope. We use the spectroscopic observations to identify velocity-coherent structures (filaments and clumps) and study their properties at a resolution of 0.4 pc. The region contains two main velocity components: first component shows four filaments between -63 and -55 km/s forming a spiral structure converging in a hub, the second filamentary component at -72 km/s harbors a massive young stellar object and possibly interacts with the hub. The clumps harbouring the three main YSOs in the region are massive (187-535 Msun), have luminosities consistent with B-type stars, have central densities of ~10^6 cm^-3 and drive large outflows. Majority of the velocity-coherent clumps in the region show virial parameters between 2-7, which considering the detection of protostars implies collapse to be gradual. We conclude that the region consists of a network of filaments through which mass accretes (~10^-4 Msun/yr) onto the hub. The hub and some of the ends of filaments appear to be undergoing collapse to form new stars. This study identifies a target region for future high resolution observations that could probe the link between the core and filament evolution.

We present JEMS (JWST Extragalactic Medium-band Survey), the first public medium-band imaging survey carried out using JWST/NIRCam and NIRISS. These observations use $\sim2\mu$m and $\sim4\mu$m medium-band filters (NIRCam F182M, F210M, F430M, F460M, F480M; and NIRISS F430M & F480M in parallel) over 15.6 square arcminutes in the Hubble Ultra Deep Field (UDF), thereby building on the deepest multi-wavelength public datasets available anywhere on the sky. We describe our science goals, survey design, NIRCam and NIRISS image reduction methods, and describe our first data release of the science-ready mosaics. Our chosen filters create a JWST imaging survey in the UDF that enables novel analysis of a range of spectral features potentially across the redshift range of $0.3<z<20$, including Paschen-$\alpha$, H$\alpha$+[NII], and [OIII]+H$\beta$ emission at high spatial resolution. We find that our JWST medium-band imaging efficiently identifies strong line emitters (medium-band colors $>1$ magnitude) across redshifts $1.5<z<9.3$, most prominently H$\alpha$+[NII] and [OIII]+H$\beta$. We present our first data release including science-ready mosaics of each medium-band image available to the community, adding to the legacy value of past and future surveys in the UDF. We also describe future data releases. This survey demonstrates the power of medium-band imaging with JWST, informing future extragalactic survey strategies using JWST observations.

We have built and tested a compact, low-cost, but very-high-performance astronomical polarimeter based on a continuously rotating half-wave plate and a high-speed imaging detector. The polarimeter is suitable for small telescopes up to ~1 m in aperture. The optical system provides very high transmission over a wide wavelength range from the atmospheric UV cutoff to ~1000 nm. The high-quantum-efficiency, low-noise and high-speed of the detectors enable bright stars to be observed with high-precision as well as polarization imaging of extended sources. We have measured the performance of the instrument on 20 cm and 60 cm aperture telescopes. We show some examples of the type of science possible with this instrument. The polarimeter is particularly suited to studies of the wavelength dependence and time variability of the polarization of stars and planets.

Dirac, in 1937 proposed the variation of coupling constants derived from his large number hypothesis. Efforts have continued since then to constrain their variation by various methods. We briefly discuss several methods used for the purpose while focusing primarily on the use of supernovae type 1a, quasars, and gamma-ray bursts (GRBs) as cosmological probes for determining cosmological distances. Supernovae type Ia (SNeIa) are considered the best standard candles since their intrinsic luminosity can be determined precisely from their light curves. However, they have only been observed up to about redshift $z=2.3$, mostly at $z<1.5$. Quasars are the brightest non-transient cosmic sources in the Universe. They have been observed up to $z=7.5$. Certain types of quasars can be calibrated well enough for their use as standard candles but with a higher degree of uncertainty in their intrinsic luminosity than the SNeIa. GRBs are even brighter than quasars, observed up to $z=9.4$. Their radiation lasts from 10s of milliseconds to several minutes and, in rare cases, for a few hours. However, they are even more challenging to calibrate as standard candles than quasars. What if the standard candles' intrinsic luminosities are affected when the coupling constants become dynamic? This paper uses our earlier finding that the speed of light c, the gravitational constant G, the Planck constant h, and the Boltzmann constant k variations are correlated as $G\thicksim c^{3}\thicksim h^{3}\thicksim k^{3/2}$ with $(\dot{G}/G)_{0}=3(\dot{c}/c)_{0}=(\dot{h}/h)_{0}=1.5 (\dot{k}/k)_{0}=5.4H_{0} =3.90(\pm 0.04)\times 10^{-10} yr^{-1}$ corroborates it with SNeIa, quasars, and GRBs observational data. Also, we show that this covarying coupling constant model may be better than the standard {\Lambda}CDM model for using quasars and GRBs as standard candles and predict the mass of the GRBs scales as $((1+z)^{1/3}-1)$.

Mapping out the populations of thick disk and halo brown dwarfs is important for understanding the metallicity dependence of low-temperature atmospheres and the substellar mass function. Recently, a new population of cold and metal-poor brown dwarfs has been discovered, with $T_{\rm{eff}}$ $\lesssim$ 1400 K and metallicity $\lesssim$ $-$1 dex. This population includes what may be the first known "extreme T-type subdwarfs" and possibly the first Y-type subdwarf, WISEA J153429.75$-$104303.3. We have conducted a Gemini YJHK/Ks photometric follow-up campaign targeting potentially metal-poor T and Y dwarfs, utilizing the GNIRS and Flamingos-2 instruments. We present 14 near-infrared photometric detections of 8 unique targets: six T subdwarf candidates, one moderately metal poor Y dwarf candidate, and one Y subdwarf candidate. We have obtained the first ever ground-based detection of the highly anomalous object WISEA J153429.75$-$104303.3. The F110W$-$$J$ color of WISEA J153429.75$-$104303.3 is significantly bluer than that of other late-T and Y dwarfs, indicating that WISEA J153429.75$-$104303.3 has an unusual spectrum in the 0.9-1.4 $\mu$m wavelength range which encompasses the $J$-band peak. Our $J$-band detection of WISEA J153429.75$-$104303.3 and corresponding model comparisons suggest a subsolar metallicity and temperature of 400-550 K for this object. JWST spectroscopic follow-up at near-infrared and mid-infrared wavelengths would allow us to better understand the spectral peculiarities of WISEA J153429.75$-$104303.3, assess its physical properties, and conclusively determine whether or not it is the first Y-type subdwarf.

Reasonable parametrizations of the current Hubble data set of the expansion rate of our homogeneous and isotropic universe, after suitable smoothing of these data, strongly suggests that the area of the apparent horizon increases irrespective of whether the spatial curvature of the metric is open, flat or closed. Put in another way, any sign of the spatial curvature appears consistent with the second law of thermodynamics.

We present results of X-ray spectral and time-domain variability analyses of 4 faint, "quiescent" blazars from the Swift-BAT 105-month catalog. We use observations from a recent, 5-month long NICER campaign, as well as archival BAT data. Variations in the 0.3-2 keV flux are detected on minute, $\sim$weekly, and monthly timescales, but we find that the fractional variability $F_{\rm var}$ on these timescales is $<25\%$ and decreases on longer timescales, implying generally low-amplitude variability across all sources and showing very low variability on monthly timescales ($F_{\rm var}\lesssim13\%$), which is at odds with previous studies that show that blazars are highly variable in the X-rays on a wide range of timescales. Moreover, we find that the flux variability on very short timescales appears to be characterized by long periods of relative quiescence accompanied by occasional short bursts, against the relatively time-stationary nature of the variability of most other AGN light curves. Our analysis also shows that the broadband X-ray spectra (0.3-195 keV) of our sources can be described with different power law models. As is the case with most blazars, we find that 2 sources (2MASS J09343014-1721215 and PKS 0312-770) are well-modeled with a simple power law, while the remaining two (1RXS J225146.9-320614 and PKS 2126-15) exhibit curvature in the form of a log-parabolic power law. We also find that, in addition to the continuum, PKS 2126-15 requires significant absorption at the soft X-rays ($\lesssim$1 keV) to fully describe the observed curvature, possibly due to absorption from the intergalactic medium.

Modern large ground-based solar telescopes are invariably equipped with adaptive optics systems to enhance the high angular resolution imaging and spectroscopic capabilities in the presence of the Earth's atmospheric turbulence. The quality of the images obtained from these telescopes can not be quantified with the Strehl ratio or other metrics that are used for nighttime astronomical telescopes directly. In this paper, we propose to use the root mean square (rms) granulation contrast as a metric to quantify the image quality of ground-based solar telescopes. We obtain semi-logarithmic plots indicating the correspondence between the Strehl ratio and the rms granulation contrast for most practical values of the telescope diameters (D) and the atmospheric coherence diameters ($ r_0$), for various levels of adaptive optics compensation. We estimate the efficiency of a few working solar adaptive optics systems by comparing the results of our simulations with the Strehl ratio and rms granulation contrast published by these systems. Our results can be used in conjunction with a plausible 50 system efficiency to predict the lower bound on the rms granulation contrast expected from ground-based solar telescopes.

We analyze broadband X-ray data of NGC 6946 X-1 and probe plausible accretion scenarios in this ULX. NGC 6946 X-1 is a persistent soft source with broadband continuum spectra described by two thermal disk components. The cool accretion disk temperature $\rm T_{cool} \sim 0.2$ keV and the presence of $\sim 0.9$ keV emission/absorption broad feature suggests the evidence of optically thick wind due to super-critical accretion. The hot geometrically modified accretion disk has an inner temperature of $\rm T_{hot} \sim 2$ keV with a radial dependent profile $\rm T(r) \propto r^{-0.5}$, expected in a slim disk scenario. Further, the measurement based on a realistic inclination angle of the disk indicates that the mass of the host compact object is comparable to $\rm \sim 6-10 ~M_{\odot}$ non-rotating black hole or the system hosts a weakly magnetized neutron star with $\rm B \lesssim 2 \times 10^{11}$ G magnetic field. Overall, the detected spectral curvature, high luminosity, flux contribution from two thermal disk components, and estimated accretion rate imprint the super-Eddington accretion scenario.

NASA's Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting near bright stars. It has identified more than 250 transiting exoplanets, and almost 6,000 candidates are yet to be studied. In this manuscript, we discuss the findings from the ongoing VaTEST (Validation of Transiting Exoplanets using Statistical Tools) project, which aims to validate new exoplanets for further characterization. We validated 16 new exoplanets by examining the light curves of 30 candidates using LATTE tool and computing the False Positive Probabilities using multiple statistical validation tools like VESPA and TRICERATOPS. These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-277b, TOI-1853b and TOI-3082b) and for both transmission and emission spectroscopy (TOI-672b, TOI-1410b, TOI-1694b, TOI-2018b, TOI-2134b and TOI-2443b); Two super-Earths (TOI-1801b and TOI-2194b) orbiting bright (V = 11.58 mag, V = 8.42 mag), metal-poor ([Fe/H] = -0.7186 $\pm$ 0.1, [Fe/H] = -0.3720 $\pm$ 0.1) stars; two short-period Neptune like planets (TOI-1410b and TOI-1853b) in Hot Neptune Desert. In total, we validated 2 super-Earths, 9 sub-Neptunes, 3 Neptune-like, and 2 sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify three more candidates (TOI-1732, TOI-2200, and TOI-5704) which can be further studied to establish their planetary nature.

The study of meter and sub-meter scale geological features, especially boulders and boulder fields, on the surface of airless bodies can provide insight into the evolution of the regolith and the contribution of various processes to its formation. Prior studies have examined the photometric properties of the lunar regolith surrounding young craters using image ratios. We extend this methodology to extracting surface properties, in particular the roughness characteristics, exclusive to boulder fields and the boulders that constitute them around impact craters. In this study, rock-rich regions on the Moon are investigated using photometric roughness by employing a normalised logarithmic phase ratio difference metric to measure and compare the slope of the phase curve (reflectance versus phase angle) of a rock-rich field to a rock-free field. We compare the photometric roughness of rock-rich fields on simulated images with the photometric roughness of rock-rich fields on LROC NAC images (0.5m/pixel). Using this technique, we determine that rock-rich surfaces are not necessarily photometrically rougher than rock-free areas. Additionally, we find the roughness of resolved rock fields to indicate the presence of diverse sub-mm scale rock roughness (microtopography) and, possibly, variable rock single scattering albedo. These latter properties are likely controlled by rock petrology and material response to weathering and erosion. Spatial clustering of photometrically smooth and rough boulder fields in the downrange and uprange of two craters is observed, reflecting ejecta asymmetry and possibly indicating asymmetric modification of ejecta rock surfaces during the impact excavation process.

We have performed intensive follow-up observations of a Type IIn/Ia-CSM SN (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the results of our observations focusing on optical/near-infrared (NIR) photometry and spectroscopy. The maximum V-band magnitude of SN 2020uem is over $-19.5$ mag. The light curves decline slowly with a rate of $\sim 0.75 {\rm ~mag}/100 {\rm ~days}$. In the late phase ($\gtrsim 300$ days), the light curves show accelerated decay ($\sim 1.2 {\rm ~mag}/100 {\rm ~days}$). The optical spectra show prominent hydrogen emission lines and broad features possibly associated with Fe-peak elements. In addition, the $\rm H\alpha$ profile exhibits a narrow P-Cygni profile with the absorption minimum of $\sim 100 {\rm ~km~s^{-1}}$. SN 2020uem shows a higher $\rm H\alpha/H\beta$ ratio ($\sim 7$) than those of SNe IIn, which suggests a denser CSM. The NIR spectrum shows the Paschen and Brackett series with continuum excess in the H and Ks bands. We conclude that the NIR excess emission originates from newly-formed carbon dust. The dust mass ($M_{\rm d}$) and temperature ($T_{\rm d}$) are derived to be $(M_{\rm d}, T_{\rm d}) \sim (4-7 \times 10^{-5} {\rm ~M_{\odot}}, 1500-1600 {\rm ~K})$. We discuss the differences and similarities between the observational properties of SNe IIn/Ia-CSM and those of other SNe Ia and interacting SNe. In particular, spectral features around $\sim 4650$ {\text \AA} and $\sim 5900$ {\text \AA} of SNe IIn/Ia-CSM are more suppressed than those of SNe Ia; these lines are possibly contributed, at least partly, by \ion{Mg}{1}] and \ion{Na}{1}, and may be suppressed by high ionization behind the reverse shock caused by the massive CSM.

The observation of energetic astronomical sources emitting very high-energy gamma-rays in the TeV spectral range (as e.g. supernova remnants or blazars) is mainly based on detecting the Cherenkov light induced by relativistic particles in the showers produced by the photon interaction with the Earth atmosphere. The ASTRI Mini-Array is an INAF-led project aimed observing such celestial objects in the 1 - 100 TeV energy range. It consists of an array of nine innovative imaging atmospheric Cherenkov telescopes that are an evolution of the dual-mirror aplanatic ASTRI-Horn telescope operating at the INAF "M.C. Fracastoro" observing station (Serra La Nave, Mount Etna, Italy). The ASTRI Mini-Array is currently under construction at the Observatorio del Teide (Tenerife, Spain). In this paper, we present the compact (diameter 660mm, height 520mm, weight 73kg) ASTRI-Horn prototype Cherenkov Camera based on a modular multipixel Silicon Photon Multiplier (SiPM) detector, has been acquiring data since 2016 and allowing us to obtain both scientific data and essential lessons. In this contribution, we report the main features of the camera and its evolution toward the new Cherenkov camera, which will be installed on each ASTRI Mini-Array telescope to cover an unprecedented field of view of 10.5{\deg}.

The formation mechanism of the most massive stars is far from completely understood. It is still unclear if the formation is core-fed or clump-fed, i.e. if the process is an extension of what happens in low-mass stars, or if the process is more dynamical such as a continuous, multi-scale accretion from the gas at parsec (or even larger) scales. In this context we introduce the SQUALO project, an ALMA 1.3 mm and 3 mm survey designed to investigate the properties of 13 massive clumps selected at various evolutionary stages, with the common feature that they all show evidence for accretion at the clump scale. In this work we present the results obtained from the 1.3 mm continuum data. Our observations identify 55 objects with masses in the range 0.4 <~ M <~ 309 M_sun, with evidence that the youngest clumps already present some degree of fragmentation. The data show that physical properties such as mass and surface density of the fragments and their parent clumps are tightly correlated. The minimum distance between fragments decreases with evolution, suggesting a dynamical scenario in which massive clumps first fragment under the influence of non-thermal motions driven by the competition between turbulence and gravity. With time gravitational collapse takes over and the fragments organize themselves into more thermally supported objects while continuing to accrete from their parent clump. Finally, one source does not fragment, suggesting that the support of other mechanisms (such as magnetic fields) is crucial only in specific star-forming regions.

Type IIn/Ia-CSM supernovae (SNe IIn/Ia-CSM) are classified by their characteristic spectra, which exhibit narrow hydrogen emission lines originating from a strong interaction with a circumstellar medium (CSM) together with broad lines of intermediate-mass elements. We performed intensive follow-up observations of SN IIn/Ia-CSM 2020uem, including photometry, spectroscopy, and polarimetry. In this paper, we focus on the results of polarimetry. We performed imaging polarimetry at $66$ days and spectropolarimetry at $103$ days after the discovery. SN 2020uem shows a high continuum polarization of $1.0-1.5\%$ without wavelength dependence. Besides, the polarization degree and position angle keep roughly constant. These results suggest that SN 2020uem is powered by a strong interaction with a confined and aspherical CSM. We performed a simple polarization modeling, based on which we suggest that SN 2020uem has an equatorial-disk/torus CSM. Besides, we performed semi-analytic light-curve modeling and estimated the CSM mass. We revealed that the mass-loss rate in the final few hundred years immediately before the explosion of SN 2020uem is in the range of $0.01 - 0.05 {\rm ~M_{\odot}~yr^{-1}}$, and that the total CSM mass is $0.5-4 {\rm ~M_{\odot}}$. The CSM mass can be accommodated by not only a red supergiant (RSG) but a red giant (RG) or an asymptotic-giant-branch (AGB) star. As a possible progenitor scenario of SN 2020uem, we propose a white-dwarf binary system including an RG, RSG or AGB star, especially a merger scenario via common envelope evolution, i.e., the core-degenerate scenario or its variant.

We use 1-m class telescopes and the Transiting Exoplanet Survey Satellite (TESS) to explore the photometric variability of all known rapidly rotating ($v\sin{i}\gtrsim30$ km\,s$^{-1}$) ultra-cool ($\geq$M7) dwarfs brighter than $I\approx17.5$ mag. For a sample of 13 M7--L1.5 dwarfs without prior photometric periods, we obtained $I$-band light curves with the SMARTS 1.3m and WIYN 0.9m telescopes and detected rotation-modulated photometric variability in three of them. Seven of our targets were also observed by TESS and six of them show significant periodicities compatible with the estimated rotation periods of the targets. We investigate the potential of TESS to search for rotation-modulated photometric variability in ultra-cool dwarfs and find that its long stare enables $<$80~h periodic variations to be retrieved with $\leq$1\% amplitudes for ultra-cool dwarfs up to a TESS magnitude of 16.5. We combine these results with the periods of all other known photometrically-periodic ultra-cool dwarfs from the literature, and find that the periods of ultra-cool dwarfs range between 1 and 24 h, although the upper limit is likely an observational bias. We also observe that the minimum rotation periods follow a lower envelope that runs from $\approx$2 h at spectral type $\approx$M8 to $\approx$1 h at spectral type T.

There are approximately 250 quasars discovered at redshift $z\geq6$, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we report the results of our dual-frequency observations with the Very Long Baseline Array (VLBA) of two such recently discovered quasars, VIKING J231818.35$-$311346.3 at $z=6.44$ and FIRST J233153.20$+$112952.11 at $z=6.57$. Both extremely distant sources were imaged with VLBI for the first time. The radio properties of the former are consistent with those of quasars with young radio jets. The latter has an UV/optical spectrum characteristic of BL Lac objects, of which no others have been found beyond redshift 4 so far. Our VLBA observations revealed a flat-spectrum compact radio source.

We present extensive optical/ultraviolet observations and modelling analysis for the nearby SN 1987A-like peculiar Type II supernova (SN) 2018hna. Both photometry and spectroscopy covered phases extending to $>$500 days after the explosion, making it one of the best-observed SN II of this subtype. SN 2018hna is obviously bluer than SN 1987A during the photospheric phase, suggesting higher photospheric temperature, which may account for weaker BaII $\mathrm{\lambda}$6142 lines in its spectra. Analysis of early-time temperature evolution suggests a radius of $\sim$45 $\mathrm{R_{\odot}}$ for the progenitor of SN 2018hna, consistent with a blue supergiant (BSG). By fitting the bolometric light curve with hydrodynamical models, we find that SN 2018hna has an ejecta mass of $\sim$(13.7--17.7) $\mathrm{M_{\odot}}$, a kinetic energy of $\sim$ (1.0--1.2) $\times 10^{51}$ erg, and a $^{56}$Ni mass of about 0.05 $\mathrm{M_{\odot}}$. Moreover, based on standard stellar evolution and the oxygen mass (0.44--0.73 $\mathrm{M_{\odot}}$) deduced from nebular [OI] lines, the progenitor of SN 2018hna is expected to have an initial main-sequence mass $<$16 $\mathrm{M_{\odot}}$. In principle, such a relatively low-mass star cannot end as a BSG just before core-collapse, except some unique mechanisms are involved, such as rapid rotation, restricted semiconvection, etc. On the other hand, binary scenario may be more favourable, like in the case of SN 1987A. While the much lower oxygen mass inferred for SN~2018hna may imply that its progenitor system also had much lower initial masses than that of SN 1987A.

The EU ESCAPE project is developing ESAP, ESFRI 1 Scientific Analysis Platform, as an API gateway that enables the seamless integration of independent services accessing distributed data and computing resources. In ESCAPE we are exploring the possibility of exploiting EGI's OpenStack cloud computing services through ESAP. In our contribution we briefly describe ESCAPE and ESAP, the the use cases, the work done to automate a virtual machine creation in EGI's OpenStack cloud computing, drawbacks and possible solutions.

It is possible to explain the discrepancy (tension) between the local measurement of the cosmological parameter $H_0$ (the Hubble constant) and its value derived from the Planck-mission measurements of the Cosmic Microwave Background (CMB) by considering contamination of the CMB by emission from some medium surrounding distant extragalactic sources (a distant foreground), such as extremely cold coarse-grain (grey) dust. As any other foreground, it would alter the CMB power spectrum and contribute to the dispersion of CMB temperature fluctuations. By generating random samples of CMB with different dispersions, we have checked that the increased dispersion leads to a smaller estimated value of $H_0$, the rest of the cosmological model parameters remaining fixed. This might explain the reduced value of the {\it Planck}-derived parameter $H_0$ with respect to the local measurements. The cold grey dust for some time has been suspected to populate intergalactic space and it is known to be almost undetectable, except for the effect of dimming remote extragalactic sources.

In this work we have updated the list of AGN detected by INTEGRAL taking into account the new objects listed in the last published INTEGRAL/IBIS survey. We have collected 83 new AGN increasing the number of INTEGRAL detected active galaxies (436) by 19%. Half of these new additions are located behind the Galactic plane; for most of them we have full X-ray coverage obtained through archival data from Swift/XRT, XMM-Newton and NuSTAR. This allowed us to associate each high-energy emitter with a single or multiple X-ray counterpart/s and characterise the spectral shape of these new AGN by estimating the photon index, the intrinsic absorption and the 2-10 keV flux. A few cases where two soft X-ray counterparts fall within the INTEGRAL error circle and at least one is classified as an AGN have been found and discussed in detail. Thirty-four sources originally listed as AGN candidates or unidentified objects have been recognised as AGN by employing three diagnostic tests: WISE colours, radio emission and morphology. For 12 sources, among the 34 AGN candidates, we reduced optical spectra and confirmed their AGN nature, providing also their optical class and redshift. This paper is part of an on-going effort to keep the INTEGRAL AGN catalogue updated in order to provide the scientific community with a hard X-ray selected sample of active galaxies well classified and spectrally characterised.

We examine the possibility of Primordial Black Holes (PBHs) formation in single-field models of inflation. We show that a one-loop correction to the renormalized primordial power spectrum rules out the possibility of having large mass PBHs. We consider a framework in which PBHs are produced during the transition from Slow Roll (SR) to Ultra Slow Roll (USR) followed by the end of inflation. We demonstrate that the Dynamical Renormalization Group (DRG) resummed power spectrum severely restricts the possible mass range of produced PBHs in the said transition, namely, $M_{\rm PBH}\sim 10^{2}{\rm gm}$ $\widehat{a}$ la a no-go theorem. In particular, we find that the produced PBHs are short-lived ($t^{\rm evap}_{\rm PBH}\sim 10^{-17}{\rm sec}$) and the corresponding number of e-folds in the USR region is restricted to $\Delta N_{\rm USR}\approx 2$.

We present our calculations of the thermal neutrino radiation that accompanies the explosion of a minimum-mass neutron star. In this case, the neutrino luminosity is lower than the luminosity during a supernova explosion approximately by five orders of magnitude, while the energy carried away by neutrinos is low compared to the explosion energy. We also show that the energy losses through neutrinos do not hinder the envelope heating and the cumulation of the shock during its breakout and the acceleration of the outer part of the envelope to ultrarelativistic speeds.

The next Galactic core-collapse supernova (CCSN) will be a unique opportunity to study within a fully multi-messenger approach the explosion mechanism responsible for the formation of neutron stars and stellar-mass black holes. State-of-the-art numerical simulations of those events reveal the complexity of the gravitational-wave emission which is highly stochastic. This challenges the possibility to infer the properties of the compact remnant and of its progenitor using the information encoded in the waveforms. In this paper we take further steps in a program we recently initiated to overcome those difficulties. In particular we show how oscillation modes of the proto-neutron star, highly visible in the gravitational-wave signal, can be used to reconstruct the time evolution of their physical properties. Extending our previous work where only the information from a single detector was used we here describe a new data-analysis pipeline that coherently combines gravitational-wave detectors' data and infers the time evolution of a combination of the mass and radius of the compact remnant. The performance of the method is estimated employing waveforms from 2D and 3D CCSN simulations covering a progenitor mass range between 11$\mathrm{M_{\odot}}$\, and 40$\mathrm{M_{\odot}}$\, and different equations of state for both a network of up to five second-generation detectors and the proposed third-generation detectors Einstein Telescope and Cosmic Explorer. Our study shows that it will be possible to infer PNS properties for CCSN events occurring in the vicinity of the Milky Way, up to the Large Magellanic Cloud, with the current generation of gravitational-wave detectors.

Large scale primordial magnetic fields (PMFs) threading the intergalactic medium are observed ubiquitously in the Universe playing a key role in the cosmic evolution. Their origin is still debated constituting a very active field of research. In the present Letter, we propose a novel natural ab initio mechanism for the origin of such PMFs through the portal of primordial black holes (PBHs). In particular, by considering PBHs furnished with a locally isothermal disk we study the generation of a Biermann battery induced seed magnetic field (MF) due to the vortexlike motion of the primordial plasma around the black hole. Interestingly, we find a seed PMF before Big Bang Nucleosynthesis which scales with the PBH mass $M_\mathrm{PBH}$ as $B\simeq 1.5\times 10^{-4}M_\odot/M_\mathrm{PBH}$, and which accounting for the effect of cosmic expansion gives rise to a MF of a present day amplitude of the order of $10^{-30}\mathrm{G}$ independently on the PBH mass or equivalently on the scale considered. This seed MF can be later amplified by various dynamo/instability processes and provide the seed for the present day magnetic field on galactic and intergalactic scales.

As cosmic rays (CRs) propagate in the Galaxy, they can be affected by magnetic structures that temporarily trap them and cause their trajectories to display chaotic behavior, therefore modifying the simple diffusion scenario. When CRs arrive at the Earth, they do so anisotropically. These chaotic effects can be a fundamental contributor to this anisotropy. Accordingly, this requires a comprehensive description of chaos in trapping conditions since assessing their repercussions on the CR arrival directions is necessary. This study utilizes a new method described in L\'opez-Barquero and Desiati (2021) to characterize chaotic trajectories in bound systems. This method is based on the Finite-Time Lyapunov Exponent (FTLE), a quantity that determines the levels of chaos based on the trajectories' divergence rate. The FTLE is useful since it adapts to trapping conditions in magnetic structures or even propagating media changes. Here, we explore the effects that chaos and trapping can have on the TeV CR anisotropy. Concretely, we apply this method to study the behavior of CRs entering the heliosphere. Specifically, how the distinct heliospheric structures and CR impinging directions from the ISM can affect chaos levels. The heliosphere has an intrinsic directionality that affects CRs differently depending on where they enter it. This feature causes preferential directions from which particles tend to be more chaotic than others. This eventually translates into changes in the arrival maps which are not uniformly distributed. Instead, we expect sectors in the map to change separately from others, creating a time variation that could be detected. Consequently, this result points to the idea that time-variability in the maps is essential to understanding the CR anisotropy's overall processes.

Simulations of asteroid binaries commonly use mutual gravitational potentials approximated by series expansions, leading to truncation errors, and also preventing correct computations of the forces and torques when the bodies are close. We make of a recently developed method where the mutual potential is calculated with the use of surface integrals and is exact for bodies of ellipsoidal shapes. The solutions produced by the surface integration method are compared with an approach that expands the mutual potential, truncated at second and fourth order. The approximate solutions are generated with the ``General Use Binary Asteroid Simulator'' (gubas). We find that the differences in the forces and torques are the largest when the bodies are nearly touching. These differences can exceed 1000% if the shape of the primary is highly elongated. Long term simulations show more than 100% difference in the dynamics if the bodies are initially close, while the differences are negligible if the bodies are initially far apart. For simulations with two triaxial ellipsoids, the computational efficiency of the surface integral method is comparable to fourth order approximations with gubas, and superior to potentials truncated to order eight or higher.

We report a comprehensive study of the cyanopolyyne chemistry in the prototypical prestellar core L1544. Using the 100m Robert C. Byrd Green Bank Telescope (GBT) we observe 3 emission lines of HC$_3$N, 9 lines of HC$_5$N, 5 lines of HC$_7$N, and 9 lines of HC$_9$N. HC$_9$N is detected for the first time towards the source. The high spectral resolution ($\sim$ 0.05 km s$^{-1}$) reveals double-peak spectral line profiles with the redshifted peak a factor 3-5 brighter. Resolved maps of the core in other molecular tracers indicates that the southern region is redshifted. Therefore, the bulk of the cyanopolyyne emission is likely associated with the southern region of the core, where free carbon atoms are available to form long chains, thanks to the more efficient illumination of the interstellar field radiation. We perform a simultaneous modelling of the HC$_5$N, HC$_7$N, and HC$_9$N lines, to investigate the origin of the emission. To enable this analysis, we performed new calculation of the collisional coefficients. The simultaneous fitting indicates a gas kinetic temperature of 5--12 K, a source size of 80$\arcsec$, and a gas density larger than 100 cm$^{-3}$. The HC$_5$N:HC$_7$N:HC$_9$N abundance ratios measured in L1544 are about 1:6:4. We compare our observations with those towards the the well-studied starless core TMC-1 and with the available measurements in different star-forming regions. The comparison suggests that a complex carbon chain chemistry is active in other sources and it is related to the presence of free gaseous carbon. Finally, we discuss the possible formation and destruction routes in the light of the new observations.

We have carried out numerical simulations of the convection zone in a K dwarf of 0.7 solar masses rotating at the solar rotation period. We study the convection pattern, the differential rotation and meridional flows, and the dynamo-generated magnetic field. We find that for a star of this type, the solar rotation period represents a case of fairly rapid rotation and the differential is solar-type. A dynamo-generated large scale field appears but it is neither dipolar nor does it show a simple activity cycle.

The precessional motion of binary black holes can be classified into one of three morphologies, based on the evolution of the angle between the components of the spins in the orbital plane: Circulating, librating around 0, and librating around $\pi$. These different morphologies can be related to the binary's formation channel and are imprinted in the binary's gravitational wave signal. In this paper, we develop a Bayesian model selection method to determine the preferred spin morphology of a detected binary black hole. The method involves a fast calculation of the morphology which allows us to restrict to a specific morphology in the Bayesian stochastic sampling. We investigate the prospects for distinguishing between the different morphologies using gravitational waves in the Advanced LIGO/Advanced Virgo network with their plus-era sensitivities. For this, we consider fiducial high- and low-mass binaries having different spin magnitudes and signal-to-noise ratios (SNRs). We find that in the cases with high spin and high SNR, the true morphology is strongly favored with $\log_{10}$ Bayes factors $\gtrsim 4$ compared to both alternative morphologies when the binary's parameters are not close to the boundary between morphologies. However, when the binary parameters are close to the boundary between morphologies, only one alternative morphology is strongly disfavored. In the low-spin or low-SNR cases, the true morphology is still favored with a $\log_{10}$ Bayes factor $\sim 2$ compared to one alternative morphology. We also consider the gravitational wave signal from GW200129_065458 that has some evidence for precession (modulo data quality issues) and find that there is no preference for a specific morphology. Our method for restricting the prior to a given morphology is publicly available through an easy-to-use Python package called bbh_spin_morphology_prior.

With over 200 registered participants, this fully online conference allowed theorists and observers across the globe to discuss recent findings on the central structures of disc galaxies. By design, this conference included experts on the Milky Way, local and high-redshift galaxies, and theoretical aspects of galaxy formation and evolution. The need for such a broad range of expertise stems from the important advances that have been made on all fronts in recent years. One of the main goals of this meeting was accordingly to bring together these different communities, to find a common ground for discussion and mutual understanding, to exchange ideas, and to efficiently communicate progress.

Magnetars have been considered as progenitors of magnetar giant flares (MGFs) and fast radio bursts (FRBs). We present detailed studies on afterglow emissions caused by bursts that occur in their wind nebulae and surrounding baryonic ejecta. In particular, following the bursts-in-bubble model proposed by Murase, Kashiyama \& M\'esz\'aros (2016), we analytically and numerically calculate spectra and light curves of such afterglow emission. We scan parameter space for the detectability of radio signals, and find that a burst with $\sim10^{45}~{\rm erg}$ is detectable with the Very Large Array or other next-generation radio facilities. The detection of multi-wavelength afterglow emission from MGFs and/or FRBs is of great significance for their localization and revealing their progenitors, and we estimate the number of detectable afterglow events.

Diffuse gamma-ray line emission traces freshly produced radioisotopes in the interstellar gas, providing a unique perspective on the entire Galactic cycle of matter from nucleosynthesis in massive stars to their ejection and mixing in the interstellar medium. We aim at constructing a model of nucleosynthesis ejecta on galactic scale which is specifically tailored to complement the physically most important and empirically accessible features of gamma-ray measurements in the MeV range, in particular for decay gamma-rays such as $^{26}$Al, $^{60}$Fe or $^{44}$Ti. Based on properties of massive star groups, we developed a Population Synthesis Code which can instantiate galaxy models quickly and based on many different parameter configurations, such as the star formation rate, density profiles, or stellar evolution models. As a result, we obtain model maps of nucleosynthesis ejecta in the Galaxy which incorporate the population synthesis calculations of individual massive star groups. Based on a variety of stellar evolution models, supernova explodabilities, and density distributions, we find that the measured $^{26}$Al distribution from INTEGRAL/SPI can be explained by a Galaxy-wide population synthesis model with a star formation rate of $4$-$8\,\mathrm{M_{\odot}\,yr^{-1}}$ and a spiral-arm dominated density profile with a scale height of at least 700 pc. Our model requires that most massive stars indeed undergo a supernova explosion. This corresponds to a supernova rate in the Milky Way of $1.8$-$2.8$ per century, with quasi-persistent $^{26}$Al and $^{60}$Fe masses of $1.2$-$2.4\,\mathrm{M_{\odot}}$ and $1$-$6\,\mathrm{M_{\odot}}$, respectively. Comparing the simulated morphologies to SPI data suggests that a frequent merging of superbubbles may take place in the Galaxy, and that an unknown but strong foreground emission at 1.8 MeV could be present.

The nature of dark matter (DM) is an open question in cosmology, despite its abundance in the universe. While elementary particles have been posited to explain DM, compact astrophysical objects such as black holes formed in the early universe offer a theoretically appealing alternate route. Here, we constrain the fraction of DM that can be made up of primordial black holes (PBHs) with masses $M \gtrsim 0.01 M_\odot$, using the Type Ia supernova Hubble diagram. Utilizing the Dyer-Roeder distance relation, where the homogeneous matter fraction is parameterized with $\eta$, we find a maximum fractional amount of DM in compact objects ($f_p$) of 0.50 at 95\% confidence level (C.L.), in the flat $\Lambda$CDM model and 0.49 when marginalising over a constant dark energy equation of state. These limits do not change when marginalising over cosmic curvature, demonstrating the robustness to the cosmological model. When allowing for the prior on $\eta$ to include $\eta > 1$, we derive $f_p < 0.32$ at 95$\%$ C.L., showing that the prior assumption of $\eta \leq 1$ gives a conservative upper limit on $f_p$. When including Cepheid calibrated supernovae, the 95\% C.L. constraints improve to $f_p < 0.25$. We find that the estimate for the Hubble constant in our inference is consistent with the homogeneous case, showing that inhomogeneities in the form of compact dark matter cannot account for the observed Hubble tension. In conclusion, we strongly exclude the possibility that PBHs with stellar masses and above form a dominant fraction of the dark matter.

The atmospheres of small exoplanets likely derive from a combination of geochemical outgassing and primordial gases left over from formation. Secondary atmospheres, such as those of Earth, Mars and Venus, are sourced by outgassing. Persistent outgassing into long-lived, primordial, hydrogen-helium envelopes produces hybrid atmospheres of which there are no examples in the Solar System. We construct a unified theoretical framework for calculating the outgassing chemistry of both secondary and hybrid atmospheres, where the input parameters are the surface pressure, oxidation and sulfidation states of the mantle, as well as the primordial atmospheric hydrogen, helium and nitrogen content. Non-ideal gases (quantified by the fugacity coefficient) and non-ideal mixing of gaseous components (quantified by the activity coefficient) are considered. Both secondary and hybrid atmospheres exhibit a rich diversity of chemistries, including hydrogen-dominated atmospheres. The abundance ratio of carbon dioxide to carbon monoxide serves as a powerful diagnostic for the oxygen fugacity of the mantle, which may conceivably be constrained by James Webb Space Telescope spectra in the near future. Methane-dominated atmospheres are difficult to produce and require specific conditions: atmospheric surface pressures exceeding $\sim 10$ bar, a reduced (poorly oxidised) mantle and diminished magma temperatures (compared to modern Earth). Future work should include photochemistry in these calculations and clarify the general role of atmospheric escape. Exoplanet science should quantify the relationship between the mass and oxygen fugacity for a sample of super Earths and sub-Neptunes; such an empirical relationship already exists for Solar System bodies.

A circumsolar dust ring has been recently discovered close to the orbit of Mercury. There are currently no hypotheses for the origin of this ring in the literature, so we explore four different origin scenarios here: the dust originated from (1) the sporadic meteoroid complex that comprises the major portion of the Zodiacal Cloud, (2) recent asteroidal/cometary activity, (3) hypothetical dust-generating bodies locked in mean-motion resonances beyond Mercury, and (4) bodies co-orbiting with Mercury. We find that only scenario (4) reproduces the observed structure and location of Mercury's dust ring. However, the lifetimes of Mercury's co-orbitals (<20 Ma) preclude the primordial origin of the co-orbiting source population due to dynamical instability and meteoroid bombardment, demanding a recent event feeding the observed dust ring. We find that an impact on Mercury can eject debris into the co-orbital resonance. We estimate the ages of six candidate impacts that formed craters larger than 40 km in diameter using high-resolution spacecraft data from MESSENGER and find two craters with estimated surface ages younger than 50 Ma. We find that the amount of mass transported from Mercury's surface into the co-orbital resonance from these two impacts is several orders of magnitude smaller than what is needed to explain the magnitude of Mercury's ring inferred from remote sensing. Therefore we suggest that numerous younger, smaller impacts collectively contributed to the origin of the ring. We conclude that the recent impact hypothesis for the origin of Mercury's dust ring is a viable scenario, whose validity can be constrained by future inner solar system missions.

Over ten years ago, Fermi observed an excess of GeV gamma rays from the Galactic Center whose origin is still under debate. One explanation for this excess involves annihilating dark matter; another requires an unresolved population of millisecond pulsars concentrated at the Galactic Center. In this work, we use the results from LIGO/Virgo's most recent all-sky search for quasi-monochromatic, persistent gravitational-wave signals from neutron stars, to determine whether unresolved millisecond pulsars could actually explain this excess. First, we choose a luminosity function that determines the number of millisecond pulsars required to explain the observed excess. Then, we consider two models for deformations on millisecond pulsars to determine their ellipticity distributions, which are directly related to their gravitational-wave radiation. Lastly, based on null results from the Frequency-Hough all-sky search for continuous gravitational waves, we find that a large set of the parameter space in the pulsar luminosity function can be excluded. We also evaluate how these exclusion regions may change with respect to various model choices. Our results are the first of their kind and represent a bridge between gamma-ray astrophysics, gravitational-wave astronomy, and dark-matter physics.

Cross-correlations of CMB lensing reconstructions with other tracers of matter constrain primordial non-Gaussianity, neutrino masses and structure growth as a function of cosmic time. We formalize a method to improve the precision of these measurements by using a third tracer to remove structure from the lensing reconstructions. Crucially, our method enjoys the variance reduction benefits of a joint-modelling approach without the need to model the cosmological dependence of the ancillary tracer. We present a first demonstration of variance cancellation using data from Planck and the DESI Legacy Surveys, showing a 10-20% reduction in both lensing power and cross-correlation variance using the Cosmic Infrared Background (CIB) or DESI Legacy Survey Luminous Red Galaxies (LRGs) as matter tracers.

We report 235 GHz linear and circular polarization (LP and CP) detections of Sgr A* at levels of $\sim10\%$ and $\sim-1\%$, respectively, using ALMA. We describe the first full-Stokes modeling of an observed submillimeter flare with an adiabatically-expanding synchrotron hotspot using a polarized radiative transfer prescription. Augmented with a simple full-Stokes model for the quiescent emission, we jointly characterize properties of both the quiescent and variable components by simultaneously fitting all four Stokes parameter light curves. The hotspot has magnetic field strength $71$ G, radius $0.75$ Schwarzschild radii, and expands at speed $0.013$c assuming magnetic equipartition. The magnetic field's position angle projected in the plane-of-sky is $\approx55^\circ$ East of North, which previous analyses reveal as the accretion flow's angular momentum axis and further supports Sgr A* hosting a magnetically-arrested disk. The magnetic field is oriented approximately perpendicular to the line of sight, which suggests repolarization as the cause of the high circular-to-linear polarization ratio observed at radio frequencies. We additionally recover several properties of the quiescent emission, consistent with previous analyses of the accretion flow, such as a rotation measure $\approx-4.22\times10^{5}$ rad m$^{-2}$. Our findings provide critical constraints for interpreting and mitigating the polarized variable emission in future Event Horizon Telescope images of Sgr A*.

It is proved that spherically symmetric extermal black holes possess at least one external light ring. Our remarkably compact proof is based on the dominant energy condition which characterizes the external matter fields in the non-vacuum extremal black-hole spacetimes.

We derive the minimum spin value for the light black holes, $10^{-15}-1 \; M_\odot$, to experience superradiance via scalar, vector and tensor perturbations, corresponding to boson mass range $10^{-12}-10^5$ eV. We find that superradiance instability can happen even for very low spin values, ${\widetilde a} \sim 10^{-3}-10^{-2}$. Since light black holes (BHs) are very unstable to these perturbations and sensitive probes of bosonic particles, a single moderately spinning BH can probe/cover 2-3 orders of magnitude scalar (axion), vector (dark photon and/or photon with effective mass) and spin-2 mass. If superradiance exists, this drives the spin of the BH to almost zero immediately, independent of the BH formation mechanism. In the case that superradiance is not observed, we find the limits on the self-interaction and energy density. We finally touch briefly the superradiance implications on the Standard Model bosons and Higgs self-interaction.

The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: Ar$^{36}$, Ar$^{38}$, and Ar$^{40}$. We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019.

The flavor evolution of a neutrino gas can show ''slow'' or ''fast'' collective motion. In terms of the usual Bloch vectors to describe the mean-field density matrices of a homogeneous neutrino gas, the slow two-flavor equations of motion (EOMs) are $\dot{\mathbf{P}}_\omega=(\omega\mathbf{B}+\mu\mathbf{P})\times\mathbf{P}_\omega$, where $\omega=\Delta m^2/2E$, $\mu=\sqrt{2} G_{\mathrm{F}} (n_\nu+n_{\bar\nu})$, $\mathbf{B}$ is a unit vector in the mass direction in flavor space, and $\mathbf{P}=\int d\omega\,\mathbf{P}_\omega$. For an axisymmetric angle distribution, the fast EOMs are $\dot{\mathbf{D}}_v=\mu(\mathbf{D}_0-v\mathbf{D}_1)\times\mathbf{D}_v$, where $\mathbf{D}_v$ is the Bloch vector for lepton number, $v=\cos\theta$ is the velocity along the symmetry axis, $\mathbf{D}_0=\int dv\,\mathbf{D}_v$, and $\mathbf{D}_1=\int dv\,v\mathbf{D}_v$. We discuss similarities and differences between these generic cases. Both systems can have pendulum-like instabilities (soliton solutions), both have similar Gaudin invariants, and both are integrable in the classical and quantum case. Describing fast oscillations in a frame comoving with $\mathbf{D}_1$ (which itself may execute pendulum-like motions) leads to transformed EOMs that are equivalent to an abstract slow system. These conclusions carry over to three flavors.

Light sterile neutrinos with a mass of $\sim 1$ eV continue to be interesting due to multiple hints from terrestrial experiments. This simple hypothesis suffers from strong astrophysical constraints, in particular from the early universe. We develop a novel cosmologically viable proposal consistent with the terrestrial hints, as well as solar and atmospheric constraints, by sourcing the sterile neutrino's mass from ordinary matter via an ultralight scalar $\phi$ which can also be the dark matter. In this scenario, the experimentally implied $\sim 1$ eV sterile neutrino mass is a local value, generated by the Earth, and changes throughout spacetime.

The last five years have seen remarkable progress in our quest to determine the equation of state of neutron rich matter. Recent advances across the theoretical, experimental, and observational landscape have been incorporated in a Bayesian framework to refine existing covariant energy density functionals previously calibrated by the properties of finite nuclei. In particular, constraints on the maximum neutron star mass from pulsar timing, on stellar radii from the NICER mission, on tidal deformabilities from the LIGO-Virgo collaboration, and on the dynamics of pure neutron matter as predicted from chiral effective field theories, have resulted in significant refinements to the models, particularly to those predicting a stiff symmetry energy. Still, even after these improvements, we find challenging to reproduce simultaneously the neutron skin thickness of both ${}^{208}$Pb and ${}^{48}$Ca recently reported by the PREX/CREX collaboration.

We analyze inhomogeneous cosmological models in the local Universe, based on the Lemaitre-Tolman-Bondi (LTB) metric and developed using linear perturbation theory on a homogeneous and isotropic Universe background. Focusing on the different evolution of spherical symmetric inhomogeneities, we want to compare the $\Lambda$LTB model, in which the cosmological constant $\Lambda$ is included in the LTB formalism, with inhomogeneous cosmological models based on $f(R)$ modified gravity theories viewed in the Jordan frame. In particular, we adopt the Hu-Sawicki $f(R)$ model in the Jordan frame to describe the cosmic accelerated phase for the background Universe. The key difference between the $\Lambda$LTB model and the $f(R)$ gravity in an inhomogeneous cosmology is outlined by the 0-1 component of the gravitational field equations, since it intrinsically links the metric tensor components to the non-minimally coupled scalar field, present in the Jordan frame. We solve the system of field equations for both cosmological models adopting the method of separation of variables: we can integrate analytically the radial profiles of local perturbations, while their time evolution requires a numerical approach. The main result of the analysis concerns the different radial profiles of local inhomogeneities in the two cosmological scenarios: the radial perturbations follow a power-law in the $\Lambda$LTB model, while Yukawa-like contributions appear in the $f(R)$ theory. Interestingly, this latter peculiar behavior of radial profiles is not affected by the choice of the $f(R)$ functional form. The numerical solution of time-dependent perturbations exhibits a non-diverging profile. This work suggests that investigations about local inhomogeneities in the late Universe may allow us to discriminate if the present cosmic acceleration is caused by a cosmological constant term or a modified gravity effect.

We examine the effects of a massive concentric ring around a spheroid or an ellipsoid with uniform density and uniform rotation. Equilibrium sequences of axisymmetric Maclaurin-like spheroid and triaxial Jacobi-like ellipsoids are obtained. Due to the gravitational field of the ring, Maclaurin-like spheroid does not have a spherical limit when the object's angular frequency vanishes. At a critical value of the eccentricity of the spheroid's meridional section, a triaxial Jacobi-like ellipsoid bifurcates. When a parameter characterizing the gravitational field of the ring is smaller than a threshold, the bifurcation points of Maclaurin-like and Jacobi-like ellipsoids exist and the critical eccentricity is slightly larger than that of the classical Maclaurin-to-Jacobi bifurcation. When the parameter exceeds the threshold, the Maclaurin-like spheroid does not have the bifurcation point and the Jacobi-like ellipsoid appears at the lower eccentricity than the Maclaurin-like spheroid. By comparisons of the energy of the ellipsoids with the same angular momentum, it is shown that the critical point of bifurcation does not correspond to the onset of the secular instability of Maclaurin-like spheroid. It is concluded that the gravitational field of a massive ring surrounding a uniformly rotating spheroid stabilizes it against a bar-shaped deformation due to viscous dissipations.

We study nonlinear effects of perturbations around a cosmological background in projected massive gravity, which admits self-accelerating solutions in an open FLRW universe. Using the zero-curvature scaling limit, we derive nonlinear equations containing all the relevant terms on subhorizon scales. We find that the solution for a scalar graviton vanishes completely for all scales, which agrees with the linear perturbation analysis in the previous study. In addition, the effects on the gravitational potential due to the next order perturbation are strongly suppressed within the horizon. Therefore, a screening mechanism is no longer needed for consistency with solar-system experiments in the projected massive gravity.

We consider a generic Metric-Affine Cosmological setup and classify some particularly interesting specific cases of Perfect Hyperfluids. In particular, we present the form of conservation laws for the cases of pure spin, pure dilation and pure shear fluids. We also develop the concept of an incompressible hyperfluid and pay special attention to the case of a hypermomentum preserving hyperfluid. We also give a specific example on the emergence of the spin, dilation and shear currents through matter-connection couplings. In addition, starting from the generalized acceleration equation for the scale factor including torsion and non-metricity we provide a first integral of motion relating the latter with the rest of the hyperfluid variables. These results then formalize the analysis of the non-Riemannian effects in Cosmology.

The dynamical stability of quadruple-star systems has traditionally been treated as a problem involving two `nested' triples which constitute a quadruple. In this novel study, we employed a machine learning algorithm, the multi-layer perceptron (MLP), to directly classify 2+2 and 3+1 quadruples based on their stability (or long-term boundedness). The training data sets for the classification, comprised of $5\times10^5$ quadruples each, were integrated using the highly accurate direct $N$-body code MSTAR. We also carried out a limited parameter space study of zero-inclination systems to directly compare quadruples to triples. We found that both our quadruple MLP models perform better than a `nested' triple MLP approach, which is especially significant for 3+1 quadruples. The classification accuracies for the 2+2 MLP and 3+1 MLP models are 94% and 93% respectively, while the scores for the `nested' triple approach are 88% and 66% respectively. This is a crucial implication for quadruple population synthesis studies. Our MLP models, which are very simple and almost instantaneous to implement, are available on GitHub, along with Python3 scripts to access them.

Photons preferentially Compton scatter perpendicular to the plane of polarisation. This property can be exploited to design instruments to measure the linear polarisation of hard X-rays ($\sim$10 - 100 keV). Photons may undergo two interactions in the sensitive volume of the instrument, i.e. a scattering followed by an absorption. Depending on the materials used to detect these two interactions, the Compton polarimeter can be classified as single-phase (same material for scattering and absorption detectors) or dual-phase (different materials). Different designs have been studied and adopted, and current instruments are predominantly with sensors based on scintillation- or solid-state detectors. X-ray polarimetry requires much higher statistics than e.g. spectrometry or timing, thus systematic effects must be accurately measured and accounted for. In this chapter we introduce the basic formalism of the Compton effect; we describe the design schemes developed so far for scattering polarimeters, including both the single-phase and dual-phase approaches; we overview the calibration methods to reduce the systematic effects; and we describe sources of background which affect the measurements.

We study the first gravitational wave, GW150914, detected by advanced LIGO and constructed from the data of measurement of strain relative deformation of the fabric of spacetime. We show that the time series from the gravitational wave obeys Tsallis's $q$-Gaussian distribution as a probability density and its dynamics evolve of the three associated Tsallis' indices named $q$-triplet. This fact strongly suggests that these black hole merger systems behave in a non-extensive manner. Furthermore, our results point out that the entropic indexes obtained as a function of frequency are useful statistical parameters to determine the dominant frequency when black hole coalescence is achieved.

Primary charges multiply in the magnetosphere of neutron stars by electromagnetic cascade. This is accounted for the first time when computing the flux generated by axion-photon resonance, noting: (i) axions of up to dozens of meV of mass mix in the magnetized plasma; (ii) radio signal from isolated stars of inferable multiplicity factor is undetectable, which could extend up to infrared; (iii) observation of Galactic populations is also unpromising, as the boost is exiguous; (iv) telescopes could yet be sensitive to gravitational focusing of dark matter, e.g., SGR 1745-2900 orbiting Sgr A*.