Papers for Tuesday, Jul 12 2022

Axion-like particles, including the QCD axion, are well-motivated dark matter candidates. Numerical simulations have revealed coherent soliton configurations, also known as boson stars, in the centers of axion halos. We study evolution of axion solitons immersed into a gas of axion waves with Maxwellian velocity distribution. Combining analytical approach with controlled numerical simulations we find that heavy solitons grow by condensation of axions from the gas, while light solitons evaporate. We deduce the parametric dependence of the soliton growth/evaporation rate and show that it is proportional to the rate of the kinetic relaxation in the gas. The proportionality coefficient is controlled by the product of the soliton radius and the typical gas momentum or, equivalently, the ratio of the gas and soliton virial temperatures. We discuss the asymptotics of the rate when this parameter is large or small.

At high densities in compact astrophysical sources, the coherent forward scattering of neutrinos onto each other is responsible for making the flavor evolution non-linear. Under the assumption of spherical symmetry, we present the first simulations tracking flavor transformation in the presence of neutrino-neutrino forward scattering, neutral and charged current collisions with the matter background, as well as neutrino advection. We find that, although flavor equipartition could be one of the solutions, it is not a generic outcome, as often postulated in the literature. Intriguingly, the strong interplay between flavor conversion, collisions, and advection leads to a spread of flavor conversion across the neutrino angular distributions and neighboring spatial regions. Our simulations show that slow and fast flavor transformations occur simultaneously. In the light of this, looking for crossings in the electron neutrino lepton number as a diagnostic tool of the occurrence of flavor transformation in the high-density regime is a limiting method.

Neutrinos are expected to freestream (i.e. not interact with anything) since they decouple in the early Universe at a temperature $T\sim 2~{\rm MeV}$. However, there are many relevant particle physics scenarios that can make neutrinos interact at $T< 2~{\rm MeV}$. In this work, we take a global perspective and aim to identify the temperature range in which neutrinos can interact given current cosmological observations. We consider a generic set of rates parametrizing neutrino interactions and by performing a full Planck cosmic microwave background (CMB) analysis we find that neutrinos cannot interact significantly for redshifts $2000 \lesssim z \lesssim 10^5$, which we refer to as the freestreaming window. We also derive a redshift dependent upper bound on a suitably defined interaction rate $\Gamma_\text{nfs}(z)$, finding $\Gamma_\text{nfs}(z)/H(z)\lesssim 1-10$ within the freestreaming window. We show that these results are largely model independent under some broad assumptions, and contextualize them in terms of neutrino decays, neutrino self-interactions, neutrino annihilations, and majoron models. We provide examples of how to use our model independent approach to obtain bounds in specific scenarios, and demonstrate agreement with existing results. We also investigate the reach of upcoming cosmological data finding that CMB Stage-IV experiments can improve the bound on $\Gamma_\text{nfs}(z)/H(z)$ by up to a factor $10$. Moreover, we comment on large-scale structure observations, finding that the ongoing DESI survey has the potential to probe uncharted regions of parameter space of interacting neutrinos. Finally, we point out a peculiar scenario that has so far not been considered, and for which relatively large interactions around recombination are still allowed by Planck data due to some degeneracy with $n_s$, $A_s$ and $H_0$. This scenario can be fully tested with CMB-S4.

An understanding of the abundance and distribution of water vapor in the innermost region of protoplanetary disks is key to understanding the origin of habitable worlds and planetary systems. Past observations have shown H2O to be abundant and a major carrier of elemental oxygen in disk surface layers that lie within the inner few au of the disk. The combination of high abundance and strong radiative transitions leads to emission lines that are optically thick across the infrared spectral range. Its rarer isotopologue H2-18O traces deeper into this layer and will trace the full content of the planet forming zone. In this work, we explore the relative distribution of H2-16O and H2-18O within a model that includes water self-shielding from the destructive effects of ultraviolet radiation. In this Letter we show that there is an enhancement in the relative H2-18O abundance high up in the warm molecular layer within 0.1-10 au due to self-shielding of CO, C18O, and H2O. Most transitions of H2-18O that can be observed with JWST will partially emit from this layer, making it essential to take into account how H2O self-shielding may effect the H2O to H2-18O ratio. Additionally, this reservoir of H2-18O-enriched gas in combination with the vertical "cold finger" effect might provide a natural mechanism to account for oxygen isotopic anomalies found in meteoritic material in the solar system

Parsec-scale massive black hole binaries (MBHBs) are expected to form in hierarchical models of structure formation. Even though different observational strategies have been designed to detect these systems, a theoretical study is a further guide for their search and identification. In this work, we investigate the hosts properties and the electromagnetic signatures of massive black holes gravitationally bound on parsec-scales with primary mass $\rm {>}\,10^7\,M_{\odot}$. For that, we construct a full-sky lightcone by the use of the semi-analytical model L-Galaxies in which physically motivated prescriptions for the formation and evolution of MBHBs have been included. Our predictions show that the large majority of the MBHBs are placed either in spiral galaxies with a classical bulge structure or in elliptical galaxies. Besides, the scaling relations followed by MBHBs are indistinguishable from the ones of single massive black holes. We find that the occupation fraction of parsec-scale MBHBs reaches up to ${\sim}\,50\%$ in galaxies with $\rm M_{stellar}\,{>}\,10^{11}\, M_{\odot}$ and drops below 10\% for $\rm M_{stellar}\,{<}\,10^{11}\, M_{\odot}$. Our model anticipates that the majority of parsec-scale MBHBs are unequal mass systems and lie at $z\,{\sim}\,0.5$, with ${\sim}\,20$ objects per $\rm deg^2$ in the sky. However, most of these systems are inactive, and only $1\,{-}\,0.1$ objects per $\rm deg^2$ have an electromagnetic counterpart with a bolometric luminosity in excess of $10^{43}$ erg/s. Very luminous phases of parsec-scale MBHBs are more common at $z\,{>}\,1$ but the number of binaries per $\rm deg^2$ is ${\lesssim}\,0.01$ at $\rm L_{\rm bol}\,{>}\,10^{45} \rm erg/s$.

The excitation of density and bending waves in Saturn's C ring by planetary oscillation modes presents a unique opportunity to learn about gas giant interiors and rotation. However, theoretical complications related to Saturn's rapid and differential rotation pose a barrier to the full utilization of ring wave detections. We calculate oscillation modes using a complete, non-perturbative treatment of differential rotation modelled after Saturn's zonal winds in self-consistently computed, polytropic equilibria. We find that previous, approximate treatments of the effects of differential rotation in Saturn overestimate shifts in the frequencies of fundamental modes (f-modes) thought to be responsible for the majority of the waves detected in the C ring, due to an omitted modification of the equilibrium shape and structure of the planet by differential rotation. The bias introduced by these frequency overestimates is small, but significant relative to the uncertainties afforded by Cassini data. We additionally consider the non-perturbative effects of Saturn-like differential rotation on the rotational mixing of f-modes and internal gravity modes (g-modes), which is relevant to detections of multiple density waves with very closely split pattern speeds. We find that higher order rotational effects can produce orders-of-magnitude enhancements in the surface gravitational perturbations of g-modes dominated by large spherical harmonic degrees $\ell$, regardless of frequency separation from the sectoral f-mode. Despite this enhancement, we find that the observed fine-splitting of density waves is unlikely to involve g-modes dominated by $\ell\gtrsim 10$. This restriction may aid in the inference of possible internal structures for Saturn.

The Second Swift-XRT Point Source catalogue offers a combination of sky coverage and sensitivity and presents an invaluable opportunity for transient discovery. We search the catalogue at the positions of inactive and active galaxies, and identify transient candidates by comparison with XMM-Newton and ROSAT. We recover 167 previously known transients and find 19 sources consistent with being new sources, estimating a completeness of $\sim65\%$. These 19 new sources are split approximately equally between inactive and active hosts and their peak X-ray luminosities span $\sim 10^{42} - 10^{47}$ erg s$^{-1}$. We find eight are best fit with non-thermal spectral models and one with a blackbody. We also discuss our methodology and its application to the forthcoming Living Swift-XRT Point Source catalogue for the potential near real time serendipitous discovery of $\sim$ few new X-ray transients per year.

We study the nature of the low-redshift CGM in the Simba cosmological simulations as traced by ultraviolet absorption lines around galaxies in bins of stellar mass ($M_\star>10^{10}M_\odot$) for star-forming, green valley and quenched galaxies at impact parameters $r_\perp\leq 1.25r_{200}$. We generate synthetic spectra for HI, MgII, CII, SiIII, CIV, and OVI, fit Voigt profiles to obtain line properties, and estimate the density, temperature, and metallicity of the absorbing gas. We find that CGM absorbers are most abundant around star forming galaxies with $M_\star < 10^{11}M_\odot$, while the abundance of green valley galaxies show similar behaviour to those of quenched galaxies, suggesting that the CGM "quenches" before star formation ceases. HI absorbing gas exists across a broad range of cosmic phases (condensed gas, diffuse gas, hot halo gas and Warm-Hot Intergalactic Medium), while essentially all low-ionisation metal absorption arises from condensed gas. OVI absorbers are split between hot halo gas and the WHIM. The fraction of collisionally ionised CGM absorbers is $\sim 25-55\%$ for CIV and $\sim 80-95\%$ for OVI, depending on stellar mass and impact parameter. In general, the highest column density absorption features for each ion arise from dense gas. Satellite gas, defined as that within $10r_{1/2,\star},$ contributes $\sim 3\%$ of overall HI absorption but $\sim 30\%$ of MgII absorption, with the fraction from satellites decreasing with increasing ion excitation energy.

Observations suggest the dark matter and stars in early-type galaxies `conspire' to produce an unexpectedly simple distribution of total mass $\rho(r)\propto\rho^{-\gamma}$ with $\gamma\approx2$. We measure the distribution of mass in 48 early-type galaxies that gravitationally lens a resolved background source. By fitting the source light in every pixel of images from the Hubble Space Telescope, we find mean $\langle\gamma\rangle=2.075_{-0.024}^{+0.023}$ with intrinsic scatter between galaxies $\sigma_\gamma=0.172^{+0.022}_{-0.032}$. This is consistent with, and has similar precision to, traditional techniques that also require deep spectroscopic observations to measure stellar dynamics. At fixed surface mass density, we measure redshift dependence $\partial\langle\gamma\rangle/\partial z=0.345^{+0.322}_{-0.296}$ that is consistent with traditional techniques for the same sample of SLACS and GALLERY lenses. Interestingly, the consistency breaks down when we measure the dependence of $\gamma$ on a lens galaxy's surface mass density. We argue that this is tentative evidence for an inflection point in the total-mass density profile at a few times a galaxy's effective radius -- breaking the conspiracy.

We present the detection of 51 thermonuclear X-ray bursts observed from 4U 1636-536 by the Neutron Star Interior Composition Explorer (NICER) over the course of a three year monitoring campaign. We performed time resolved spectroscopy for 40 of these bursts and showed the existence of a strong soft excess in all the burst spectra. The excess emission can be characterized by the use of a scaling factor (f_a method) to the persistent emission of the source, which is attributed to the increased mass accretion rate on to the neutron star due to Poynting-Robertson drag. The soft excess emission can also be characterized by the use of a model taking into account the reflection of the burst emission off of the accretion disk. We also present time resolved spectral analysis of 5 X-ray bursts simultaneously observed by NICER and AstroSat, which confirm the main results with even greater precision. Finally, we present evidence for Compton cooling using 7 X-ray bursts observed contemporaneously with \nustar, by means of a correlated decrease in the hard X-ray lightcurve of 4U 1636-536 as the bursts start.

$R$-process enhanced stars with [Eu/Fe]$\geq+0.7$ (so-called $r$-II stars) are believed to have formed in an extremely neutron-rich environment in which a rare astrophysical event (e.g., a neutron star merger) occurred. This scenario is supported by the existence of an ultra-faint dwarf galaxy, Reticulum~II, where most of the stars are highly enhanced in $r$-process elements. In this scenario, some small fraction of dwarf galaxies around the Milky Way were $r$ enhanced. When each $r$-enhanced dwarf galaxy accreted to the Milky Way, it deposited many $r$-II stars in the Galactic halo with similar orbital actions. To search for the remnants of the $r$-enhanced systems, we analyzed the distribution of the orbital actions of $N=161$ $r$-II stars in the Solar neighborhood by using the Gaia EDR3 data. Since the observational uncertainty is not negligible, we applied a newly-developed {\it greedy optimistic clustering method} to the orbital actions of our sample stars. We found six clusters of $r$-II stars that have similar orbits and chemistry, one of which is a new discovery. Given the apparent phase-mixed orbits of the member stars, we interpret that these clusters as remnants of completely disrupted $r$-enhanced dwarf galaxies that merged with the ancient Milky Way.

The long-term rotational evolution of the old, isolated PSR B0950+08 is intriguing in that its spin-down rate displays sinusoidal like oscillations due to alternating variations, both in magnitude and sign, of the second time derivative of the pulse frequency. We show that large internal temperature to pinning energy ratio towards the base of the crust implied by the recent high surface temperature measurement leads to linear creep interaction to operate in the densest parts of the inner crust where vortex lines assume a parabolic shape due to pinning to nuclear clusters. The resulting low frequency oscillations of vortex lines combined with the time variable superfluid-external pulsar braking torque coupling give rise to oscillatory spin-down rate. We apply this model to PSR B0950+08 observations for several external torque models. Our model has potential to constrain the radial extension of the closed magnetic field region in the outer core of neutron stars from the oscillation period of the spin-down rate.

AU Mic is a young and nearby M-dwarf star harbouring a circumstellar debris disk and one recently discovered planet on an 8d orbit. Large-scale structures within the disk were also discovered and are moving outward at high velocity. We aim at studying this system with the highest spatial resolution in order to probe the innermost regions and to search for additional low-mass companion or set detection limits. The star was observed with two different techniques probing complementary spatial scales. We obtained new SAM observations with SPHERE, which we combined with data from NACO, PIONIER and GRAVITY. We did not detect additional companions within 0.02-7au from the star. We determined magnitude upper limits for companions of H~9.8mag within 0.02-0.5au, Ks~11.2mag within 0.4-2.4au and L'~10.7mag within 0.7-7au. Using theoretical isochrones, we converted into mass upper limits of ~17Mjup, ~12Mjup and ~9jup, respectively. The PIONIER observations allowed us to determine the angular diameter of AU Mic, 0.825+/-0.050mas, which converts to R = 0.862+/-0.052Rsun. We did not detect the newly discovered planets, but we derived upper limit masses for the innermost region of AU Mic. We do not have any detection with a significance beyond 3sigma, the most significant signal with PIONIER being 2.9sigma and with SPHERE being 1.6\sigma. We applied the pyMESS2 code to estimate the detection probability of companions by combining radial velocities, SPHERE imaging and our interferometric detection maps. We show that 99% of the companions down to ~0.5Mjup can be detected within 0.02au or 1Mjup down to 0.2au. The low-mass planets orbiting at <0.11au will not be directly detectable with the current AO and interferometric instruments due to its close orbit and very high contrast (~10e-10 in K). It will be also below the angular resolution and contrast limit of the next ELT IR imaging instruments.

A new generation of sky surveys is poised to provide unprecedented volumes of data containing hundreds of thousands of new strong lensing systems in the coming years. Convolutional neural networks are currently the only state-of-the-art method that can handle the onslaught of data to discover and infer the parameters of individual systems. However, many important measurements that involve strong lensing require population-level inference of these systems. In this work, we propose a hierarchical inference framework that uses the inference of individual lensing systems in combination with the selection function to estimate population-level parameters. In particular, we show that it is possible to model the selection function of a CNN-based lens finder with a neural network classifier, enabling fast inference of population-level parameters without the need for expensive Monte Carlo simulations.

Theoretical and numerical studies have shown that large-scale vortices in Protoplanetary discs can result from various hydrodynamical instabilities. Once produced, such vortices can survive nearly unchanged over a large number of rotation periods, slowly migrating towards the star. In the outer disc, self-gravity may affect the vortex evolution and must be included in models. We performed 2D hydrodynamic simulations using the RoSSBi3D code. The outline of our computations was limited to Euler's equations assuming a non-homentropic and non-adiabatic flow for an ideal gas. A series of 45 runs were carried out starting from a Gaussian vortex-model; the evolution of vortices was followed during 300 orbits for various values of the vortex parameters and the Toomre parameter. Two simulations, with the highest resolution (HR) thus far for studies of vortices, were also run to better characterise the internal structure of the vortices and for the purpose of comparison with an isothermal case. We find that SG tends to destabilise the injected vortices, but compact small-scale vortices seem to be more robust than large-scale oblong vortices. Vortex survival critically depends on the value of the disc's Toomre parameter, but may also depend on the disc temperature at equilibrium. Disc SG must be small enough to avoid destruction in successive splitting and an approximate `stability' criterion is deduced for vortices. The self-gravitating vortices that we found persist during hundreds of rotation periods and look like the quasi-steady vortices obtained in the non-self-gravitating case. A number of these self-gravitating vortices are eventually accompanied by a secondary vortex with a horseshoe motion. These vortices reach a new rotational equilibrium in their core, tend to contract in the radial direction, and spin faster.

Post-starburst (PSB) galaxies are defined as having experienced a recent burst of star formation, followed by a prompt truncation in further activity. Identifying the mechanism(s) causing a galaxy to experience a post-starburst phase therefore provides integral insight into the causes of rapid quenching. Galaxy mergers have long been proposed as a possible post-starburst trigger. Effectively testing this hypothesis requires a large spectroscopic galaxy survey to identify the rare PSBs as well as high quality imaging and robust morphology metrics to identify mergers. We bring together these critical elements by selecting PSBs from the overlap of the Sloan Digital Sky Survey and the Canada-France Imaging Survey and applying a suite of classification methods: non-parametric morphology metrics such as asymmetry and Gini-M20, a convolutional neural network trained to identify post-merger galaxies, and visual classification. This work is therefore the largest and most comprehensive assessment of the merger fraction of PSBs to date. We find that the merger fraction of PSBs ranges from 19% to 42% depending on the merger identification method and details of the PSB sample selection. These merger fractions represent an excess of 3-46x relative to non-PSB control samples. Our results demonstrate that mergers play a significant role in generating PSBs, but that other mechanisms are also required. However, applying our merger identification metrics to known post-mergers in the IllustrisTNG simulation shows that ~70% of recent post-mergers (<200 Myr) would not be detected. Thus, we cannot exclude the possibility that nearly all post-starburst galaxies have undergone a merger in their recent past.

The Trappist-1 planets provide a unique opportunity to test the current understanding of rocky planet evolution. The James Webb Space Telescope is expected to characterize the atmospheres of these planets, potentially detecting CO$_2$, CO, H$_2$O, CH$_4$, or abiotic O$_2$ from water photodissociation and subsequent hydrogen escape. Here, we apply a coupled atmosphere-interior evolution model to the Trappist-1 planets to anticipate their modern atmospheres. This model, which has previously been validated for Earth and Venus, connects magma ocean crystallization to temperate geochemical cycling. Mantle convection, magmatic outgassing, atmospheric escape, crustal oxidation, a radiative-convective climate model, and deep volatile cycling are explicitly coupled to anticipate bulk atmospheres and planetary redox evolution over 8 Gyr. By adopting a Monte Carlo approach that samples a broad range of initial conditions and unknown parameters, we make some tentative predictions about current Trappist-1 atmospheres. We find that anoxic atmospheres are probable, but not guaranteed, for the outer planets; oxygen produced via hydrogen loss during the pre-main sequence is typically consumed by crustal sinks. In contrast, oxygen accumulation on the inner planets occurs in around half of all models runs. Complete atmospheric erosion is possible but not assured for the inner planets (occurs in 20%-50% of model runs), whereas the outer planets retain significant surface volatiles in virtually all model simulations. For all planets that retain substantial atmospheres, CO$_2$-dominated or CO$_2$-O$_2$ atmospheres are expected; water vapor is unlikely to be a detectable atmospheric constituent in most cases. There are necessarily many caveats to these predictions, but the ways in which they misalign with upcoming observations will highlight gaps in terrestrial planet knowledge.

Thanks to relatively firm mode identification, possible based on period ratios only, High Amplitude Delta Scuti Stars pulsating in at least three radial modes are promising targets for asteroseismic inference. In this study we used the most numerous sample of HADS from the OGLE inner bulge fields that likely pulsate in either three or four radial modes simultaneously. We have computed a grid of pulsation models along evolutionary tracks and determined the physical parameters of stars by matching their pulsation periods and period ratios. For 176 HADS we determined physical parameters, i.e. masses, luminosities, effective temperatures, metallicities and ages. We present the distribution of physical parameters and discuss their properties. We selected 16 candidates for SX Phoenicis stars.

The diversity of the structures recently observed in protoplanetary discs (PPDs) with the new generation of high-resolution instruments have made more acute the challenging questions that planet-formation models must answer. The challenge is in the theoretical side but also in the numerical one with the need to significantly improve the performances of the codes and to stretch the limit of PPD simulations. Multi-physics, fast, accurate, high-resolution, modular, and reliable 3D codes are needed to explore the mechanisms at work in PPDs and to try explaining the observed features. We present RoSSBi3D the 3D extension of the 2D code Rotating-System Simulations for Bi-fluids (RoSSBi) which was specifically developed to study the evolution of PPDs. This is a new code, even if based on the 2D version, that we describe in detail explaining its architecture and specificity but also its performances against test cases and a PPD benchmark. We also explain the way to use it and to manage the produced data. This FORTRAN code solves the fully compressible inviscid continuity, Euler, and energy conservation equations for an ideal gas in non-homentropic conditions and for pressureless particles in a fluid approximation. It is a finite volume code which is second order in time and accounts for discontinuities thanks to an exact Riemann solver. The spatial scheme accounts for the equilibrium solution and is improved thanks to parabolic interpolation which permits to reach third order in space. The code is developed in 3D and structured for high-performance parallelism. The optimised version of the code work on high performance computers with a very good scalability. Its reliability has been checked against classical tests and a benchmark specific to PPDs that includes Rossby wave instability (RWI), streaming instability (SI), dust capture by a vortex and dust settling.

We present a detailed X-ray analysis and imaging of stellar coronae of five coronally connected eclipsing binaries, namely, 44 Boo, DV Psc, ER Vul, XY UMa, and TX Cnc. Both components of these binaries are found to be active. The X-ray light curves of detached and semidetached type systems show eclipsed-like features, whereas no evidence for coronal eclipsing is shown by the contact type systems. The X-ray light curve of DV Psc shows the O'Connell-like effect where the first maximum is found to be brighter than that of the second. Results of the coronal imaging using three-dimensional deconvolution of X-ray light curves show the coronae of all these binaries are either in the contact or over-contact configuration, with the primary being 1.7 $-$ 4 times X-ray brighter than its companion. In the current sample, a minimum of 30$-$50 \% of total UV emission is found to originate from the photosphere and positively correlated with the X-ray emission. X-ray spectra of these systems are well explained by two-temperature plasma models. The temperature corresponding to cool and hot components of plasma are found to be in the ranges of 0.25$-$0.64 and 0.9$-$1.1 keV, respectively. For the majority of binaries in the sample, the phase-resolved X-ray spectral analysis shows the orbital modulation in X-ray luminosity and emission measure corresponding to the hot component. A total of seven flaring events are also detected in the four systems with the flare energy in the range of (1.95$-$27.0)$\times$10$^{33}$ erg and loop length of the order of 10$^{9-11}$ cm.

We investigate the use of bright single pulses from the Crab pulsar to determine separately the dispersion measure (DM) for the Main Pulse and Interpulse components. We develop two approaches using cross correlation functions (CCFs). The first method computes the CCF of the total intensity of each of 64 frequency channels with a reference channel and converts the time lag of maximum correlation into a DM. The second method separately computes the CCF between every pair of channels for each individual bright pulse and extracts an average DM from the distribution of all channel-pair DMs. Both methods allow the determination of the DM with a relative uncertainty of better than 10^-5 and provide robust estimates for the uncertainty of the best-fit value. We find differences in DM between the Main Pulse, the Low Frequency Interpulse, and the High Frequency Interpulse using both methods in a frequency range from 4 to 6 GHz. Earlier observations of the High Frequency Interpulse carried out by Hankins et al. (2016) resulted in DM_HFIP-DM_MP of 0.010 +- 0.016 pc cm^-3. Our results indicate a DM_HFIP-DM_MP of 0.0127 +- 0.0011 pc cm^-3 (with DM_comp being the DM value of the respective emission component), confirming earlier results with an independent method. During our studies we also find a relation between the brightness of single pulses in the High Frequency Interpulse and their DM. We also discuss the application of the developed methods on the identification of substructures in the case of Fast Radio Bursts.

Chemical models and experiments indicate that interstellar dust grains and their ice mantles play an important role in the production of complex organic molecules (COMs). To date, the most complex solid-phase molecule detected with certainty in the ISM is methanol, but the James Webb Space Telescope (JWST) may be able to identify still larger organic species. In this study, we use a coupled chemo-dynamical model to predict new candidate species for JWST detection toward the young star-forming core Cha-MMS1, combining the gas-grain chemical kinetic code MAGICKAL with a 1-D radiative hydrodynamics simulation using Athena++. With this model, the relative abundances of the main ice constituents with respect to water toward the core center match well with typical observational values, providing a firm basis to explore the ice chemistry. Six oxygen-bearing COMs (ethanol, dimethyl ether, acetaldehyde, methyl formate, methoxy methanol, and acetic acid), as well as formic acid, show abundances as high as, or exceeding, 0.01% with respect to water ice. Based on the modeled ice composition, the infrared spectrum is synthesized to diagnose the detectability of the new ice species. The contribution of COMs to IR absorption bands is minor compared to the main ice constituents, and the identification of COM ice toward the core center of Cha-MMS1 with the JWST NIRCAM/Wide Field Slitless Spectroscopy (2.4-5.0 micron) may be unlikely. However, MIRI observations (5-28 micron) toward COM-rich environments where solid-phase COM abundances exceed 1% with respect to the water ice column density might reveal the distinctive ice features of COMs.

Thanks to the long-term collaborations between nuclear and astrophysics, we have good understanding on stellar nucleosynthesis, except for the elements around Ti and some neutron-capture elements. From the comparison between observations and Galactic chemical evolution models, it is necessary to have the rapid neutron-capture process associated with core-collapse supernovae, although the explosion mechanism is unknown. The impact of rotating massive stars is also shown in this paper. Many of the key elements can be exclusively obtained in the UV, and therefore without UV spectra it would not be possible to fully understand the origin of elements in the universe.

Motivated by the challenges of calculating the dynamical masses of late-type galaxies (LTGs) and the enormous amount of data from the Sloan Digital Sky Survey (SDSS), we calculate virial masses of a sample of approximately 126,000 LTGs from the sixteenth data release of the SDSS. The virial mass estimations were made considering Newtonian mechanics, virial equilibrium and velocity dispersion from stars and gas. The procedure gave as a result seven mass estimations for each galaxy. The calculated masses were calibrated using a sample of spiral galaxies with velocity rotation curves. Considering the results from the calibration, we find that the correlation between virial and dynamical (rotation curve) masses is stronger for high inclination values. Therefore the calibration relies more on the available data for higher inclination angle galaxies. We also show that if we have a heterogeneous sample of galaxies one must take into consideration the size and colour of these galaxies by using the following variables: Sersic index n, concentration index and colour of the stars. For relatively smaller and bluer LTGs the gas velocity dispersion provides a more consistent mass calculation, while for LTGs that are relatively larger and redder the stellar velocity dispersion provides a better correlated mass calculation.

We present a coordinated campaign of observations to monitor the brightness of the James Webb Space Telescope (JWST) as it travels toward the second Earth-Sun Lagrange point and unfolds using the network ofUnistellar digital telescopes. Those observations collected by citizen astronomers across the world allowed us to detect specific phases such as the separation from the booster, glare due to a change of orientation after a maneuver, the unfurling of the sunshield, and deployment of the primary mirror. After deployment of the sunshield on January 6 2022, the 6-h lightcurve has a significant amplitude and shows small variations due to the artificial rotation of the space telescope during commissionning. These variations could be due to the deployment of the primary mirror or some changes in orientation of the space telescope. This work illustrates the power of a worldwide array of small telescopes, operated by citizen astronomers, to conduct large scientific campaigns over a long timeframe. In the future, our network and others will continue to monitor JWST to detect potential degradations to the space environment by comparing the evolution of the lightcurve.

C-type shocks are believed to be ubiquitous in turbulent molecular clouds thanks to ambipolar diffusion. We investigate whether the drag instability in 1D isothermal C-shocks, inferred from the local linear theory of Gu & Chen, can appear in non-ideal magnetohydrodynamic simulations. Two C-shock models (with narrow and broad steady-state shock widths) are considered to represent the typical environment of star-forming clouds. The ionization-recombination equilibrium is adopted for the one-fluid approach. In the 1D simulation, the inflow gas is continuously perturbed by a sinusoidal density fluctuation with a constant frequency. The perturbations clearly grow after entering the C-shock region until they start being damped at the transition to the postshock region. We show that the profiles of a predominant Fourier mode extracted locally from the simulated growing perturbation match those of the growing mode derived from the linear analysis. Moreover, the local growth rate and wave frequency derived from the predominant mode generally agree with those from the linear theory. Therefore, we confirm the presence of the drag instability in simulated 1D isothermal C-shocks. We also explore the nonlinear behavior of the instability by imposing larger-amplitude perturbations to the simulation. We find that the drag instability is subject to wave-steepening, leading to saturated perturbation growth. Issues concerning local analysis, nonlinear effects, one-fluid approach, and astrophysical applications are discussed.

We assemble a large sample of 13,863 high-velocity stars (HiVels) with total velocity ${V}_{\rm{GSR}} \ge {\rm300} \rm{km\,s^{-1}}$, selected from the RAVE DR5, SDSS DR12, LAMOST DR8, APOGEE DR16, GALAH DR2, and $Gaia$ EDR3. In this HiVel sample, 43 sources are hypervelocity stars (HVSs) that have ${V}_{\rm{GSR}}$ exceeding their local escape velocities, $V_{\rm esc}$, 32 of which are discovered for the first time. Interestingly, all the HVSs are metal-poor and late-type, significantly different from the previous HVSs in the literature, which are largely massive, metal-rich early-type stars, identified originally by extreme radial velocity alone. This finding suggests that our newly found HVSs are ejected by different mechanisms from the previous population. To investigate their origins, for the 571 extreme HiVel stars with ${V}_{\rm{GSR}}\ge0.8V_{\rm{esc}}$ in our sample, we reconstruct their backward-integrated trajectories in the Galactic potential. According to the orbital analysis, no HVSs are found to be definitely ejected from the Galactic center (GC), while 8 late-type metal-poor HiVels are found to have a closest distance to the GC within 1 kpc. Intriguingly, 15 HiVels (including 2 HVSs) are found from their backward-integrated trajectories to have experienced a close encounter with the Sagittarius dwarf spheroidal galaxy (Sgr dSph), suggesting that they originated from this dSph. This hypothesis is supported by an analysis of the [$\alpha$/Fe]--[Fe/H] diagram. From a preliminary analysis of all the HiVels in our sample, we propose a general picture: Star ejection from Galactic subsystems such as dwarf galaxies and globular clusters, either via tidal stripping or even the Hills mechanism, can be an important channel to produce HiVels/HVSs, particularly the metal-poor late-type halo population.

The separable analytical solution in standard perturbation theory for an Einstein de Sitter (EdS) universe can be generalized to the wider class of such cosmologies ("generalized EdS", or gEdS) in which a fraction of the pressure-less fluid does not cluster. We derive the corresponding kernels in both Eulerian perturbation theory (EPT) and Lagrangian perturbation theory, generalizing the canonical EdS expressions to a one parameter family where the parameter can be taken to be the exponent $\alpha$ of the growing mode linear amplification $D(a) \propto a^{\alpha}$. Calculating the power spectrum (PS) at one loop in EPT, we find that the expected condition for infra-red convergence of the $\alpha$-dependent terms is recovered for each of the two contributing integrals ( `22' and `13' terms) separately i.e. without a requirement of cancellation of divergences between integrals. The conditions on the PS for ultraviolet convergence are the same as for $\alpha=1$, except at a specific value ($\alpha \approx 0.16$) where the coefficient of the leading divergent contribution vanishes. In the second part of the paper we show that the calculation of cosmology dependent corrections in perturbation theory in standard (e.g. LCDM-like) models can be considerably simplified, and their magnitude and parameter dependence better understood, by relating them to our analytic results for gEdS models. At second order in perturbation theory results at each redshift $z$ can be mapped exactly to a gEdS model with an effective growth exponent, $\alpha_2(z)$, determined by the cosmological parameters. For the PS at loop order, which requires going to third order, such a mapping is not exact but provides a very good approximation. We provide simplified expressions for the cosmological corrections to the PS in terms of only two redshift dependent functions and four infra-red safe integrals.

We present observations with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope of seven compact low-mass star-forming galaxies at redshifts, z,in the range 0.3161-0.4276, with various O3Mg2=[OIII]5007/MgII 2796+2803 and Mg2=MgII 2796/MgII 2803 emission-line ratios. We aim to study the dependence of leaking Lyman continuum (LyC) emission on the characteristics of MgII emission together with the dependences on other indirect indicators of escaping ionizing radiation. LyC emission with escape fractions fesc(LyC)=3.1-4.6 per cent is detected in four galaxies, whereas only 1sigma upper limits of fesc(LyC) in the remaining three galaxies were derived. A strong narrow Ly-alpha emission line with two peaks separated by Vsep~298-592 km/s was observed in four galaxies with detected LyC emission and very weak Ly-alpha emission is observed in galaxies with LyC non-detections. Our new data confirm the tight anti-correlation between fesc(LyC) and Vsep found for previous low-redshift galaxy samples. Vsep remains the best indirect indicator of LyC leakage among all considered indicators. It is found that escaping LyC emission is detected predominantly in galaxies with Mg2>1.3. A tendency of an increase of fesc(LyC) with increasing of both the O3Mg2 and Mg2 is possibly present. However, there is substantial scatter in these relations not allowing their use for reliable prediction of fesc(LyC).

The Taurid Meteoroid Complex (TMC) is a broad stream of meteoroids that produces several annual meteor showers on Earth. If the linkage between these showers and 2P/Encke is at the centre of most TMC models, the small size and low activity of the comet suggest that 2P/Encke is not the unique parent body of the Taurids. Here we simulate the formation of the TMC from 2P/Encke and several NEAs. In total, we explored more than a hundred stream formation scenarios using clones of 2P/Encke. Each modelled stream was integrated and compared with present-day Taurid observations. As previously reported, we find that even slight variations of 2P/Encke's orbit modifies considerably the characteristics of the simulated showers. Most of the comet's clones, including the nominal one, appear to reproduce the radiant structure of the Taurid meteors but do not match the observed time and duration of the showers. However, the radiants and timing of most Taurid showers are well reproduced by a particular clone of the comet. Our analysis thus suggest that with this specific dynamical history, 2P/Encke is the sole parent of the four major TMC showers which have ages from 7-21 ka. Our modelling also predicts that the 2022 Taurid Resonant Swarm return will be comparable in strength to the 1998, 2005 and 2015 returns. While purely dynamical models of Encke's orbit -- limited by chaos -- may fail to reveal the comet's origin, its meteor showers may provide the trail of breadcrumbs needed to backtrack our way out of the labyrinth.

Cosmic rays were first discovered over a century ago, however the origin of their high-energy component remains elusive. Uncovering astrophysical neutrino sources would provide smoking gun evidence for ultrahigh energy cosmic ray production. The IceCube Neutrino Observatory discovered a diffuse astrophysical neutrino flux in 2013 and observed the first compelling evidence for a high-energy neutrino source in 2017. Next-generation telescopes with improved sensitivity are required to resolve the diffuse flux. A detector near the equator will provide a unique viewpoint of the neutrino sky, complementing IceCube and other neutrino telescopes in the Northern Hemisphere. Here we present results from an expedition to the north-eastern region of the South China Sea. A favorable neutrino telescope site was found on an abyssal plain at a depth of $\sim$ 3.5 km. Below 3 km, the sea current speed was measured to be $v_{\mathrm{c}}<$ 10 cm/s, with absorption and scattering lengths for Cherenkov light of $\lambda_{\mathrm{abs} }\simeq$ 27 m and $\lambda_{\mathrm{sca} }\simeq$ 63 m, respectively. Accounting for these measurements, we present the preliminary design and capabilities of a next-generation neutrino telescope, The tRopIcal DEep-sea Neutrino Telescope (TRIDENT). With its advanced photon-detection technologies and size, TRIDENT expects to discover the IceCube steady source candidate NGC 1068 within 2 years of operation. This level of sensitivity will open a new arena for diagnosing the origin of cosmic rays and measuring astronomical neutrino oscillation over fixed baselines.

We have performed a detailed analysis of the X-ray spectra of the blazar Mkn 421 using Swift-XRT observations taken between 2005 and 2020, to quantify the correlations between spectral parameters for different models. In an earlier work, it has been shown that such spectral parameter correlations obtained from a single short flare of duration $\sim$ 5-days of Mkn 421, can be used to distinguish spectrally degenerate models and provide estimates of physical quantities. In this work, we show that the results from the long-term spectral parameter correlations are consistent with those obtained from the single flare. In particular, that the observed spectral curvature is due to maximum cutoff energy in the particle distribution is ruled out. Instead, models where the curvature is due to the energy dependence of escape or acceleration time-scale of the particles are favored. The estimated values of the physical parameters for these models are similar to the ones obtained from the single flare analysis and are somewhat incompatible with the physical assumption of the models, suggesting that more complex physical models are required. The consistency of the results obtained from the long and short-term evolution of the source, underlines the reliability of the technique to use spectral parameter correlations to distinguish physical models.

Chemical Cartography, or mapping, of our Galaxy has the potential to fully transform our view of its structure and formation. In this work, we use chemical cartography to explore the metallicity distribution of OBAF-type disk stars from the LAMOST survey and a complimentary sample of disk giant stars from Gaia DR3. We use these samples to constrain the radial and vertical metallicity gradients across the Galactic disk. We also explore whether there are detectable azimuthal variations in the metallicity distribution on top of the radial gradient. For the OBAF-type star sample from LAMOST, we find a radial metallicity gradient of $\Delta$[Fe/H]/$\Delta$R $\sim -0.078 \pm 0.001$ dex/kpc in the plane of the disk and a vertical metallicity gradient of $\Delta$[Fe/H]/$\Delta$Z $\sim -0.15 \pm 0.01$ dex/kpc in the solar neighborhood. The radial gradient becomes shallower with increasing vertical height while the vertical gradient becomes shallower with increasing Galactocentric radius, consistent with other studies. We also find detectable spatially-dependent azimuthal variations on top of the radial metallicity gradient at the level of $\sim$0.10 dex. Interestingly, the azimuthal variations appear be close to the Galactic spiral arms in one dataset (Gaia DR3) but not the other (LAMOST). These results suggest that there is azimuthal structure in the Galactic metallicity distribution and that in some cases it is co-located with spiral arms.

We report on a study of 9 nearby star-forming, very low-metallicity galaxies observed by Hubble's COS far-UV spectrograph that can serve as templates of high-z galaxies to be observed by JWST. We find that the nebular spectra of these primitive galaxies show evidence of irradiation by X-ray emitters. Following Thuan et al. (2004), we identify the sources of X-ray emission as massive X-ray binaries containing a massive accreting stellar black hole. We further find that the lower the metallicity, the higher the probability of strong X-irradiation. Following Heger et al. (2003), we suggest that these accreting black holes are produced by direct collapse of stars having initial masses greater than $\sim50\, M_\odot$. Our models of young star clusters with an embedded stellar black hole produce effects on the surrounding gaseous medium that are consistent with the observed spectra. We conclude that primitive galaxies are qualitatively different from more metal-rich galaxies in showing evidence of hard radiation that can best be explained by the presence of one or more embedded stellar black holes.

We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In the first, we utilize the known intensity pattern of unfocused stray light across the detector planes -- the dominant source of photons from diffuse sources -- to separate astrophysical emission from internal instrument backgrounds using ${\sim}$7 Ms/detector deep blank-sky exposures. In the second, we present an updated parametric model of the full NuSTAR instrument background, allowing us to leverage the statistical power of an independent ${\sim}$20 Ms/detector stacked exposures spread across the sky. Finding no evidence of anomalous x-ray lines using either method, we set limits on the active-sterile mixing angle $\sin^2(2\theta)$ for sterile-neutrino masses 6--40 keV. In particular, we strongly disfavor a ${\sim}$7-keV sterile neutrino decaying into a 3.5-keV photon. In combination with previous results, the parameter space for the Neutrino Minimal Standard Model ($\nu$MSM) is now nearly closed.

Upcoming surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will detect up to 10 million time-varying sources in the sky every night for ten years. This information will be transmitted in a continuous stream to brokers that will select the most promising events for a variety of science cases using machine learning algorithms. We study the benefits and challenges of Bayesian Neural Networks (BNNs) for this type of classification tasks. BNNs are found to be accurate classifiers which also provide additional information: they quantify the classification uncertainty which can be harnessed to analyse this upcoming data avalanche more efficiently.

Both observations and simulations suggest that the solar filament eruption is closely related to magnetic flux emergence. It is thought that the eruption is triggered by magnetic reconnection between the filament and the emerging flux. However, the details of such a reconnection are rarely presented. In this study, we report the detailed reconnection between a filament and its nearby emerging fields, that led to the reconfiguration and subsequent partial eruption of the filament located over the polarity inversion line of active region 12816. Before the reconnection, we observed repeated brightenings in the filament at a location that overlies a site of magnetic flux cancellation. Plasmoids form at this brightening region, and propagate bi-directionally along the filament. These indicate the tether-cutting reconnection that results in the formation and eruption of a flux rope. To the northwest of the filament, magnetic fields emerge, and reconnect with the context ones, resulting in repeated jets. Afterwards, another magnetic fields emerge near the northwestern filament endpoints, and reconnect with the filament, forming the newly reconnected filament and loops. Current sheet repeatedly occurs at the interface, with the mean temperature and emission measure of 1.7 MK and 1.1$\times$10$^{28}$ cm$^{-5}$. Plasmoids form in the current sheet, and propagate along it and further along the newly reconnected filament and loops. The newly reconnected filament then erupts, while the unreconnected filament remains stable. We propose that besides the orientation of emerging fields, some other parameters, such as the position, distance, strength, and area, are also crucial for triggering the filament eruption.

The evolution and stability of mass transfer of CO+He WD binaries are not well understood. Observationally they may emerge as AM CVn binaries and are important gravitational wave (GW) emitters. In this work, we have modeled the evolution of double WD binaries with accretor masses of $0.50 - 1.30\;M_{\odot}$ and donor masses of $0.17\; - 0.45\;M_{\odot}$ using the detailed stellar evolution code MESA. We find that the evolution of binaries with same donor masses but different accretor masses is very similar and binaries with same accretor masses but larger He donor masses have larger maximum mass transfer rates and smaller minimum orbital periods. We also demonstrate that the GW signal from AM CVn binaries can be detected by space-borne GW observatories, such as LISA, TianQin. And there is a linear relation between the donor mass and gravitational wave frequency during mass transfer phase. In our calculation, all binaries can have dynamically stable mass transfer, which is very different from previous studies. The threshold donor mass of Eddington-limited mass transfer for a given accretor WD mass is lower than previous studies. Assuming that a binary may enter common envelope if the mass transfer rate exceeds the maximum stable burning rate of He, we provide a new criterion for double WDs surviving mass transfer, which is below the threshold of Eddington-limit. Finally, we find that some systems with ONe WDs in our calculation may evolve into detached binaries consisting of neutron stars (NSs) and extremely low mass He WDs and further ultra-compact X-ray binaries.

Radio Frequency Interference (RFI) greatly reduces sensitivity of radio observations to astrophysical signals and creates false positive candidates in searches for radio transients. Real signals are missed while considerable computational and human resources are needed to remove RFI candidates. In the context of transient astrophysics, this makes effective RFI removal vital to effective searches for fast radio bursts and pulsars. Radio telescopes typically sample at rates that are high enough for there to be tens to hundreds of samples along the transient's pulse. Mitigation techniques should excise RFI on this timescale to account for a changing radio frequency environment. We evaluate the effectiveness of three filters, as well as a composite of the three, that excises RFI at the cadence that the data are recorded. Each of these filters operates in a different domain and thus excises as a different RFI morphology. We analyze the performance of these four filters in three different situations: (I) synthetic pulses in Gaussian noise; (II) synthetic pulses injected into real data; (III) four pulsar observations. From these tests, we gain insight into how the filters affect both the pulse and the noise level. This allows use to outline which and how the filters should be used based on the RFI present and the characteristics of the source signal. We show by flagging a small percentage of the spectrum we can substantially improve the quality of transit observations.

Bright-rimmed clouds (BRCs) are excellent laboratories to explore the radiation-driven implosion mode of star formation because they show evidence of triggered star formation. In our previous study, BRC 18 has been found to accelerate away from the direction of the ionizing Hii region because of the well known "Rocket Effect". Based on the assumption that both BRC 18 and the candidate young stellar objects (YSOs) are kinematically coupled and using the latest Gaia EDR3 measurements, we found that the relative proper motions of the candidate YSOs exhibit a tendency of moving away from the ionizing source. Using BRC 18 as a prototype, we made our further analysis for 21 more BRCs, a majority of which showed a similar trend. For most of the BRCs, the median angle of the relative proper motion of the candidate YSOs is similar to the angle of on-sky direction from the ionizing source to the central IRAS source of the BRC. Based on Pearson's and Spearman's correlation coefficients, we found a strong correlation between these two angles, which is further supported by the Kolmogorov-Smirnov (K-S) test on them. The strong correlation between these two angles supports the "Rocket Effect" in the BRCs on the plane-of-sky.

After core hydrogen burning, massive stars evolve from blue-white dwarfs to red supergiants by expanding, brightening, and cooling within few millennia. We discuss a previously neglected constraint on mass, age, and evolutionary state of Betelgeuse and Antares, namely their observed colour evolution over historical times: We place all 236 stars bright enough for their colour to be discerned by the unaided eye (V$\le$3.3 mag) on the colour-magnitude-diagram (CMD), and focus on those in the Hertzsprung gap. We study pre-telescopic records on star colour with historically-critical methods to find stars that have evolved noticeably in colour within the last millennia. Our main result is that Betelgeuse was recorded with a colour significantly different (non-red) than today (red, B$-$V=$1.78 \pm 0.05$ mag). Hyginus (Rome) and Sima Qian (China) independently report it two millennia ago as appearing like Saturn (B$-$V=$1.09 \pm 0.16$ mag) in colour and `yellow' (quantifiable as B$-$V=$0.95 \pm 0.35$ mag), respectively (together, 5.1$\sigma$ different from today). The colour change of Betelgeuse is a new, tight constraint for single-star theoretical evolutionary models (or merger models). It is most likely located less than one millennium past the bottom of the red giant branch, before which rapid colour evolution is expected. Evolutionary tracks from MIST consistent with both its colour evolution and its location on the CMD suggest a mass of $\sim$14M$_{\odot}$ at $\sim$14 Myr. The (roughly) constant colour of Antares for the last three millennia also constrains its mass and age. Wezen was reported white historically, but is now yellow.

In this work we generalize the notion of convective inhibition to apply in cases where there is an infinite reservoir of condensible species (i.e., an ocean). We propose a new model for the internal structure and thermal evolution of super-Earths with hydrogen envelopes. We derive the criterion for convective inhibition in a generalizes phase mixture from first principles thermodynamics. We then investigate the global ocean case using a water-hydrogen system, for which we have data, as an example. We then extend our arguments to apply to a system of hydrogen and silicate vapor. We then employ a simple atmospheric model to apply our findings to super-Earths and to make predictions about their internal structures and thermal evolution. For hydrogen envelope masses roughly in the range between 0.1-10% Earth's mass, convective contact between the envelope and core may shut down because of the compositional gradient that arises from silicate partial vaporization. For envelope hydrogen masses that cause the associated basal pressure to exceed the critical pressure of pure silicate (of order a couple kilobars), the base of that envelope and top of the core lie on the critical line of the two-phase hydrogen-silicate phase diagram. The corresponding temperature is much higher than convective models would suggest. The core then cools inefficiently, with intrinsic heat fluxes potentially comparable to the Earth's internal heat flux today. This low heat flux may allow the core to remain in a high entropy supercritical state for billions of years, but the details of this depend on the nature of the two-component phase diagram at high pressure, something that is currently unknown. A supercritical core thermodynamically permits the dissolution of large quantities of hydrogen into the core.

In this paper, which is the second in a series of papers, we analyse what parameters can determine the width of the radio pulsar 'death valley' in the $P$-${\dot P}$ diagram. Using exact expression for the maximum potential drop, which can be realised over magnetic polar caps and the corresponding threshold for the secondary plasma production determined in Paper I, we analyse in detail the observed distribution of pulsars taking into account all the possible parameters (radius $R$ and moment of inertia of a neutron star $I_{\rm r}$, high-energy tail in the $\gamma$-quanta energy distribution giving rise to secondary particles, etc.) which could broaden 'the death line'. We show that the consistent allowance for all these effects leads to a sufficiently wide of 'the death valley' containing all the observed pulsars even for dipole magnetic field of a neutron star.

The latest $\textit{Fermi}$-LAT gamma-ray catalog, 4FGL-DR3, presents a large fraction of sources without clear association to known counterparts, i.e., unidentified sources (unIDs). In this paper, we aim to classify them using machine learning algorithms, which are trained with the spectral characteristics of associated sources to predict the class of the unID population. With the state-of-the-art $\texttt{CatBoost}$ algorithm, based on gradient boosting decision trees, we are able to reach a 67% accuracy on a 23-class dataset. Removing a single of these classes -- blazars of uncertain type -- increases the accuracy to 81%. If interested only in a binary AGN/pulsar distinction, the model accuracy is boosted up to 99%. Additionally, we perform an unsupervised search among both known and unID population, and try to predict the number of clusters of similar sources, without prior knowledge of their classes. The full code used to perform all calculations is provided as an interactive Python notebook.

As the demand for software to support the processing and analysis of massive radio astronomy datasets increases in the era of the SKA, we demonstrate the interactive workflow building, data mining, processing, and visualisation capabilities of DUG Insight. We test the performance and flexibility of DUG Insight by processing almost 68,000 full sky radio images produced from the Engineering Development Array (EDA2) over the course of a three day period. The goal of the processing was to passively detect and identify known Resident Space Objects (RSOs: satellites and debris in orbit) and investigate how radio interferometry could be used to passively monitor aircraft traffic. These signals are observable due to both terrestrial FM radio signals reflected back to Earth and out-of-band transmission from RSOs. This surveillance of the low Earth orbit and airspace environment is useful as a contribution to space situational awareness and aircraft tracking technology. From the observations, we made 40 detections of 19 unique RSOs within a range of 1,500 km from the EDA2. This is a significant improvement on a previously published study of the same dataset and showcases the flexible features of DUG Insight that allow the processing of complex datasets at scale. Future enhancements of our DUG Insight workflow will aim to realise real-time acquisition, detect unknown RSOs, and continue to process data from SKA-relevant facilities.

The recent launch of JWST has enabled the exciting prospect of detecting the first generation of metal-free, Population III (Pop. III) stars. Determining the emission line signatures that robustly signify the presence of Pop. III stars against other possible contaminants represents a key challenge for interpreting JWST data. To this end, we run high-resolution (sub-pc) cosmological radiation hydrodynamics simulations of the region around a dwarf galaxy at $z\geq10$ to predict the emission line signatures of the Pop. III/Pop. II transition. We show that the absence of metal emission lines is a poor diagnostic of Pop. III stars because metal-enriched galaxies in our simulation can maintain low [OIII] 5007${\rm \r{A}}$ emission that may be undetectable due to sensitivity limits. Combining spectral hardness probes (e.g. HeII 1640${\rm \r{A}}$/H$\alpha$) with metallicity diagnostics is more likely to probe the presence of metal-free stars, although contamination from Wolf-Rayet stars, X-ray binaries, or black holes may be important. The hard emission from Pop. III galaxies fades fast due to the short stellar lifetimes of massive Pop. III stars, which could further inhibit detection. Similarly, Pop. III stars may be detectable after they evolve off the main-sequence due to the cooling radiation from nebular gas or a supernova remnant; however, these signatures are also short-lived (i.e. few Myr), and contaminants such as flickering black holes might confuse this diagnostic. While JWST will provide a unique opportunity to spectroscopically probe the nature of the earliest galaxies, both the short timescales associated with pristine systems and ambiguities in interpreting key diagnostic emission lines may hinder progress. Special care will be needed before claiming the discovery of systems with pure Pop. III stars.

Type Ia Supernovae (SNe Ia) have been extensively used as standardisable candles in the optical for several decades. However, SNe Ia have shown to be more homogeneous in the near-infrared (NIR), where the effect of dust extinction is also attenuated. In this work, we explore the possibility of using a low number of NIR observations for accurate distance estimations, given the homogeneity at these wavelengths. We found that one epoch in $J$ and/or $H$ band, plus good $gr$-band coverage, gives an accurate estimation of peak magnitudes in $J$ ($J_{max}$) and $H$ ($H_{max}$) bands. The use of a single NIR epoch only introduces an additional scatter of $\sim0.05$ mag for epochs around the time of $B$-band peak magnitude ($T_{max}$). We also tested the effect of optical cadence and signal-to-noise ratio (S/N) in the estimation of $T_{max}$ and its uncertainty propagation to the NIR peak magnitudes. Both cadence and S/N have a similar contribution, where we constrained the introduced scatter of each to $<0.02$ mag in $J_{max}$ and $<0.01$ in $H_{max}$. However, these effects are expected to be negligible, provided the data quality is comparable to that obtained for observations of nearby SNe ($z\lesssim0.1$). The effect of S/N in the NIR was tested as well. For SNe Ia at $0.08<z\lesssim0.1$, NIR observations with better S/N than that found in the CSP sample is necessary to constrain the introduced scatter to a minimum ($\lesssim0.05$ mag). These results provide confidence for our FLOWS project that aims in using SNe Ia with public ZTF optical light curves and few NIR epochs to map out the peculiar velocity field of the local Universe. This will allow us to determine the distribution of dark matter in our own supercluster, Laniakea, and test the standard cosmological model by measuring the growth rate of structures, parameterised by $fD$, and the Hubble-Lema\^itre constant, $H_0$.

Here we present evolutionary models for a set of massive stars, introducing a new prescription for the mass-loss rate obtained from hydrodynamical calculations in which the wind velocity profile, $v(r)$, and the line-acceleration, $g_\text{line}$, are obtained in a self consistently way. Replacing mass-loss rates at the Main Sequence stage from the standard Vink's formula by our new recipe, we generate a new set of evolutionary tracks for $M_\text{ZAMS}=25,40,70$ and $120\,M_\odot$ and metallicities $Z=0.014$ (Galactic), $Z=0.006$ (LMC), and $Z=0.002$ (SMC). Our new derived formula for mass-loss rate predicts a dependence $\dot M\propto Z^a$, where $a$ is not longer constant but dependent on the stellar mass: ranging from $a\sim0.53$ when $M_*\sim120\;M_\odot$, to $a\sim1.02$ when $M_*\sim25\;M_\odot$. We found that models adopting the new recipe for $\dot M$ retain more mass during their evolution, which is expressed in larger radii and consequently more luminous tracks over the Hertzsprung-Russell diagram. These differences are more prominent for the cases of $M_\text{ZAMS}=70$ and 120 $M_\odot$ at solar metallicity, where we found self-consistent tracks are $\sim0.1$ dex brighter and keep extra mass up to 20 $M_\odot$, compared with the classical models using the previous formulation for mass-loss rate. Moreover, we observed remarkable differences for the evolution of the radionuclide isotope $^{26}$Al in the core and the surface of the star. Since $\dot M_\text{sc}$ are weaker than the commonly adopted values for evolutionary tracks, self-consistent tracks predict a later modification in the abundance number of $^{26}$Al in the stellar winds. This new behaviour could provide useful information about the real contribution of this isotope from massive stars to the Galactic interstellar medium.

The composition of cometary ices provides key information on the thermal and chemical properties of the outer parts of the protoplanetary disk where they formed 4.6 Gy ago. This chapter reviews our knowledge of composition of cometary comae based on remote spectroscopy and in-situ investigations techniques. Cometary comae can be dominated by water vapour, CO or CO2. The abundances of several dozen of molecules, with a growing number of complex organics, have been measured in comets. Many species that are not directly sublimating from the nucleus ices have also been observed and traced out into the coma in order to determine their production mechanisms. Chemical diversity in the comet population and compositional heterogeneity of the coma are discussed. With the completion of the Rosetta mission, isotopic ratios, which hold additional clues on the origin of cometary material, have been measured in several species. Finally, important pending questions (e.g., the nitrogen deficiency in comets) and the need for further work in certain critical areas are discussed in order to answer questions and resolve discrepancies between techniques.

We present a description of A dual-Beam pOlarimetric Robotic Aperture for the Sun (ABORAS), to serve as a Solar input with a dedicated Stokes V polarimeter for the HARPS3 high-resolution spectrograph. ABORAS has three main science drivers: trying to understand the physics behind stellar variability, tracking the long-term stability of HARPS3, and serve as a benchmark for Earth-sized exoplanet detection with HARPS3 by injecting an Earth RV signal into the data. By design, ABORAS will (together with the HARPS3 instrument) be able to measure 10cm/s variations in RV of the integrated Solar disk and detect integrated magnetic field levels at sub 1 Gauss level through circularly polarized light.

In the interstellar medium, the amide-type molecules play an important role in the formation of the prebiotic molecules in the hot molecular cores or high-mass star formation regions. The complex amide-related molecule cyanamide (NH$_{2}$CN) is known as one of the rare interstellar molecule which has played a major role in the formation of urea (NH$_{2}$CONH$_{2}$). In this article, we presented the detection of the emission lines of cyanamide (NH$_{2}$CN) towards the hot molecular core G10.47+0.03 between the frequency range 158.49$-$160.11 GHz using the Atacama Large Millimeter/submillimeter Array (ALMA) interferometric radio telescope. The estimated column density of the emission lines of NH$_{2}$CN using the rotational diagram model was $N$(NH$_{2}$CN) = (6.60$\pm$0.1)$\times$10$^{15}$ cm$^{-2}$ with rotational temperature ($T_{rot}$) = 201.2$\pm$3.3 K. The fractional abundance of NH$_{2}$CN with respect to H$_{2}$ towards G10.47+0.03 was $f$(NH$_{2}$CN) = 5.076$\times$10$^{-8}$. Additionally, we estimated the NH$_{2}$CN/NH$_{2}$CHO abundance ratio towards the G10.47+0.03 was 0.170, which was nearly similar with NH$_{2}$CN/NH$_{2}$CHO abundance ratio towards IRAS 16293$-$2422 B and Sgr B2 (M). We found that the observed abundance of NH$_{2}$CN with respect to H$_{2}$ towards G10.47+0.03 fairly agrees with the theoretical value predicted by Garrod (2013). We also discussed the possible formation and destruction pathways of NH$_{2}$CN.

On Aug 22, 2016, a bright fireball was observed by the Desert Fireball Network in South Australia. Its pre-atmosphere orbit suggests it was temporarily captured by the Earth-Moon system before impact. A search was conducted two years after the fall, and a meteorite was found after 6 days of searching. The meteorite appeared relatively fresh, had a mass consistent with fireball observation predictions, and was at the predicted location within uncertainties. However, the meteorite did show some weathering and lacked short-lived radionuclides ($^{58}$Co, $^{54}$Mn). A terrestrial age based on cosmogenic $^{14}$C dating was determined; the meteorite has been on the Earth's surface for $3.2\pm1.3$ kyr, ruling out it being connected to the 2016 fireball. Using an upper limit on the pleistieocene terrain age and the total searched area, we find that the contamination probability from another fall is $<2\%$. Thus, the retrieval of the "wrong" meteorite is at odds with the contamination statistics. This is a key example to show that fireball-meteorite pairings should be carefully verified.

The use of realistic mock galaxy catalogues is essential in the preparation of large galaxy surveys, in order to test and validate theoretical models and to assess systematics. We present an updated version of the mock catalogue constructed from the Millennium-XXL simulation, which uses a halo occupation distribution (HOD) method to assign galaxies r-band magnitudes and g-r colours. We have made several modifications to the mock to improve the agreement with measurements from the SDSS and GAMA surveys. We find that cubic interpolation, which was used to build the original halo lightcone, produces extreme velocities between snapshots. Using linear interpolation improves the correlation function quadrupole measurements on small scales. We also update the g-r colour distributions so that the observed colours better agree with measurements from GAMA data, particularly for faint galaxies. As an example of the science that can be done with the mock, we investigate how the luminosity function depends on environment and colour, and find good agreement with measurements from the GAMA survey. This full-sky mock catalogue is designed for the ongoing Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey (BGS), and is complete to a magnitude limit r=20.2.

We present constraints on primordial B modes from large angular scale cosmic microwave background polarisation anisotropies measured with the Planck satellite. To remove Galactic polarised foregrounds, we use a Bayesian parametric component separation method, modelling synchrotron radiation as a power law and thermal dust emission as a modified blackbody. This method propagates uncertainties from the foreground cleaning into the noise covariance matrices of the maps. We construct two likelihoods: (i) a semi-analytical cross-spectrum-based likelihood-approximation scheme (momento) and (ii) an exact polarisation-only pixel-based likelihood (pixlike). Since momento is based on cross-spectra it is statistically less powerful than pixlike, but is less sensitive to systematic errors correlated across frequencies. Both likelihoods give a tensor-to-scalar ratio, r, that is consistent with zero from low multipole (2 <= ell < 30) Planck polarisation data. From full-mission maps we obtain r_0.05<0.274, at 95 per cent confidence, at a pivot scale of k = 0.05 Mpc^-1, using pixlike. momento gives a qualitatively similar but weaker 95 per cent confidence limit of r_0.05<0.408.

The UV/optical variability of AGN has long been thought to be driven by the X-ray illumination of the accretion disk. However, recent multi-wavelength campaigns of nearby Seyfert galaxies seem to challenge this paradigm, with an apparent discrepancy between observations and the underlying theory. In order to further probe the connection between the UV/optical and X-ray variability in AGN we developed a physical model to reproduce the UV/optical power spectra (PSDs) of AGN assuming the thermal reprocessing of the X-rays in the disk. This model offers a novel way to probe the innermost regions of AGN. We use our model to study the variability of NGC 5548 and we infer that the X-ray and UV/optical PSDs as well as the interband UV/optical time lags are all well reproduced. We also derive constraints on the source physical parameters, such as the X-ray corona height and the accretion rate. Our results suggest that X-ray disk reprocessing accounts for the full variability properties of this AGN, within the considered time scales. Using earlier data of NGC 5548, we also show that our model can reproduce its PSD in different epochs, establishing the feasibility of using PSD modelling to investigate the time evolution of a source.

We investigated inflation in the Higgs-$R^2$ model and assumed the trajectory to follow a single-field approximation called minimal two-field mode. Using this approximation, we tried to constrain the Higgs" non-minimal coupling $\xi$. During inflation, we investigated the effect of the large/small $\xi$ on the non-gaussianity. We found that large/small $\xi$ could not provide the large non-gaussianity. In this paper, we divided the preheating stage to be quadratic regime and quartic regime. During the quadratic regime, the gauge bosons production is the most dominant. However, it could not drain the whole inflation"s energy. Thus, we introduced a dark matter candidate with a large coupling drain of the whole inflation"s energy. We also found the large $\xi$ is problematic to provide successful preheating. In our paper, if the $\xi > 485$, it could prevent the preheating to exist. Also, in order to continue the preheating into the quartic regime, $\xi$ must be constrained below 10 to prevent excessively large perturbative decay. Finally, the small $\xi$ also prevents the Bose-Einstein condensation in a radiation-dominated regime, thus small reheating temperature $10^7$ GeV could be obtained in this model.

Since the late 1970s, successive satellite missions have been monitoring the sun's activity and recording the total solar irradiance (TSI). Some of these measurements have lasted for more than a decade. In order to obtain a seamless record whose duration exceeds that of the individual instruments, the time series have to be merged. Climate models can be better validated using such long TSI time series which can also help to provide stronger constraints on past climate reconstructions (e.g., back to the Maunder minimum). We propose a 3-step method based on data fusion, including a stochastic noise model to take into account short and long-term correlations. Compared with previous products scaled at the nominal TSI value of 1361 W/m2, the difference is below 0.2 W/m2 in terms of solar minima. Next, we model the frequency spectrum of this 41-year TSI composite time series with a Generalized Gauss-Markov model to help describe an observed flattening at high frequencies. It allows us to fit a linear trend into these TSI time series by joint inversion with the stochastic noise model via a maximum-likelihood estimator. Our results show that the amplitude of such trend is $\sim$ -0.004 +/- 0.004 W/(m2yr) for the period 1980 - 2021. These results are compared with the difference of irradiance values estimated from two consecutive solar minima. We conclude that the trend in these composite time series is mostly an artifact due to the colored noise.

The origin of astrophysical neutrinos has yet to be determined. The IceCube Neutrino Observatory has observed astrophysical neutrinos but has not yet identified their sources. Blazars are promising source candidates, but previous searches for neutrino emission from populations of blazars detected in $\gtrsim$ GeV gamma-rays have not observed any significant neutrino excess. Recent findings in multi-messenger astronomy indicate that high-energy photons, co-produced with high-energy neutrinos, are likely to be absorbed and reemitted at lower energies. Thus, lower-energy photons may be better indicators of TeV-PeV neutrino production. This paper presents the first time-integrated stacking search for astrophysical neutrino emission from MeV-detected blazars in the first Fermi-LAT low energy catalog (1FLE) using ten years of IceCube muon-neutrino data. The results of this analysis are found to be consistent with a background-only hypothesis. Assuming an E$^{-2}$ neutrino spectrum and proportionality between the blazars' MeV gamma-ray fluxes and TeV-PeV neutrino flux, the upper limit on the 1FLE blazar energy-scaled neutrino flux is determined to be $1.64 \times 10^{-12}$ TeV cm$^{-2}$ s$^{-1}$ at 90% confidence level. This upper limit is approximately 1% of IceCube's diffuse muon-neutrino flux measurement.

The radiative cooling time of the hot gas at the centres of cool cores in clusters of galaxies drops down to 10 million years and below. The observed mass cooling rate of such gas is very low, suggesting that AGN feedback is very tightly balanced or that the soft X-ray emission from cooling is somehow hidden from view. We use an intrinsic absorption model in which the cooling and coolest gas are closely interleaved to search for hidden cooling flows in the Centaurus, Perseus and A1835 clusters of galaxies. We find hidden mass cooling rates of between 10 to 500 Msunpyr as the cluster mass increases, with the absorbed emission emerging in the Far Infrared band. Good agreement is found between the hidden cooling rate and observed FIR luminosity in the Centaurus Cluster. The limits on the other two clusters allow for considerable hidden cooling. The implied total mass of cooled gas is much larger than the observed molecular masses. We discuss its fate including possible further cooling and collapse into undetected very cold clouds, low mass stars and substellar objects,

We show how $\varsigma$, the radial location of the minimum of the differential radial mass profile $M^\prime(r)$ of a galaxy cluster, can probe the theory of gravity. We derive $M^\prime(r)$ of the dark matter halos of galaxy clusters from N-body cosmological simulations that implement two different theories of gravity: standard gravity in the $\Lambda$CDM model and $f(R)$. We extract 49169 dark matter halos in 11 redshift bins in the range $0\leq z\leq 1$ and in three different mass bins in the range $0.9<M_{200}/10^{14}h^{-1}$M$_\odot<11$. We investigate the correlation of $\varsigma$ with the redshift and the mass accretion rate (MAR) of the halos. We show that $\varsigma$ decreases from $\sim 3R_{200}$ to $\sim 2R_{200}$ when $z$ increases from 0 to $1$ in the $\Lambda$CDM model; at $z\sim 0.1$, $\varsigma$ decreases from $2.75R_{200}$ to $\sim 2.5R_{200}$ when the MAR increases from $\sim 10^4h^{-1}$M$_\odot$yr$^{-1}$ to $\sim 2\times 10^5h^{-1}$M$_\odot$yr$^{-1}$; in the $f(R)$ model, $\varsigma$ is $\sim 15$% larger than in $\Lambda$CDM. We detect $\varsigma$ and its correlation with redshift and MAR in three samples of real clusters. We consider 129 clusters of galaxies from the Cluster Infall Regions in the Sloan Digital Sky Survey (CIRS) and the Hectospec Cluster Survey (HeCS), and 10 additional stacked clusters from the HectoMAP survey. The clusters span the redshift range $0.01 < z < 0.4$ and the mass range $\sim 10^{14}-10^{15} h^{-1}$M$_{\odot}$. The values of $\varsigma$ of real clusters appear consistent with both the $\Lambda$CDM and $f(R)$ models, because the current uncertainties on the measured mass profiles are too large. We estimate that decreasing the uncertainties by a factor of ten and distinguishing between the two theories of gravity that we investigate here requires $\gtrsim 400$ clusters, each with $\sim 200$ spectroscopic redshifts of galaxies.

The formation of inorganic cloud particles takes place in several atmospheric environments including those of warm, hot, rocky and gaseous exoplanets, brown dwarfs, and AGB stars. The cloud particle formation needs to be triggered by the in-situ formation of condensation seeds since it can not be assumed that such condensation seeds preexist in these chemically complex gas-phase environments. We aim to develop a methodology to calculate the thermochemical properties of clusters as key inputs to model the formation of condensation nuclei in gases of changing chemical composition. TiO$_2$ is used as benchmark species for cluster sizes N = 1 - 15. We create 90000 candidate geometries, for cluster sizes N = 3 - 15. We employ a hierarchical optimisation approach, consisting of a force field description, density functional based tight binding (DFTB) and all-electron density functional theory (DFT) to obtain accurate energies and thermochemical properties for the clusters. We find B3LYP/cc-pVTZ including Grimmes empirical dispersion to perform most accurately with respect to experimentally derived thermochemical properties of the TiO$_2$ molecule. We present a hitherto unreported global minimum candidate for size N = 13. The DFT derived thermochemical cluster data are used to evaluate the nucleation rates for a given temperature-pressure profile of a model hot Jupiter atmosphere. We find that with the updated and refined cluster data, nucleation becomes unfeasible at slightly lower temperatures, raising the lower boundary for seed formation in the atmosphere. The approach presented in this paper allows to find stable isomers for small (TiO$_2$)$_N$ clusters. The choice of functional and basis set for the all-electron DFT calculations have a measurable impact on the resulting surface tension and nucleation rate and the updated thermochemical data is recommended for future considerations.

On 2022 July 8, NASA shared$^{a}$ the list of five public showcase targets which have been observed with the new \textit{James Webb Space Telescope} (JWST), and whose data are expected to be released to the public around Tuesday, July 12. One of these targets is the galaxy cluster SMACS~J0723.3-7327 which acts as a gravitational lens and was recently imaged with the \textit{Hubble Space Telescope} in the framework of the \textit{Reionization Lensing Cluster Survey} program (RELICS). To facilitate studies by the community with the upcoming JWST data, we publish here a lens model for SMACS0723 -- including mass-density and magnification maps. We identify in the HST imaging five multiple-image families for three of which membership and redshift are secured by public spectroscopic data. For the remaining two systems we rely on robust photometric redshift estimates. We use here the \texttt{Light-Traces-Mass} lens modeling method, which complements the parametric models already available on the RELICS website and elsewhere, and thus helps span a representative range of solutions. The new models published here can be accessed via a link given below$^{b}$. It will be interesting to examine by how much and which properties of the mass models change, and improve, when JWST data are incorporated.

We compare two state-of-the-art numerical codes to study the overall accuracy in modeling the intergalactic medium and reproducing Lyman-$\alpha$ forest observables for DESI and high-resolution data sets. The codes employ different approaches to solving both gravity and modeling the gas hydrodynamics. The first code, Nyx, solves the Poisson equation using the Particle-Mesh (PM) method and the Euler equations using a finite volume method. The second code, \CRKHACC, uses a Tree-PM method to solve for gravity, and an improved Lagrangian smoothed particle hydrodynamics (SPH) technique, where fluid elements are modeled with particles, to treat the intergalactic gas. We compare the convergence behavior of the codes in flux statistics as well as the degree to which the codes agree in the converged limit. We find good agreement overall with differences being less than observational uncertainties, and a particularly notable $\lesssim$1\% agreement in the 1D flux power spectrum. This agreement was achieved by applying a tessellation methodology for reconstructing the density in \CRKHACC instead of using an SPH kernel as is standard practice. We show that use of the SPH kernel can lead to significant and unnecessary biases in flux statistics; this is especially prominent at high redshifts, $z \sim 5$, as the Lyman-$\alpha$ forest mostly comes from lower-density regions which are intrinsically poorly sampled by SPH particles.

We present results on the recently discovered stellar system YMCA-1, for which physical nature and belonging to any of the Magellanic System galaxies have been irresolutely analyzed. We used SMASH and {\it Gaia} EDR3 data sets to conclude that we are dealing with a small star cluster. Its reddening free, field star decontaminated colour-magnitude diagram was explored in order to obtain the cluster parameters. We found that YMCA-1 is a small (435 M$_{\odot}$), moderately old (age = 9.6 Gyr), moderately metal-poor ([Fe/H] = -1.16 dex) star cluster, located at a nearly Small Magellanic Cloud (SMC) distance (60.9 kpc) from the Sun, at $\sim$ 17.1 kpc to the East from the Large Magellanic Cloud (LMC) centre. The derived cluster brightness and size would seem to suggest some resemblance to the recently discovered faint star clusters in the Milky Way (MW) outer halo, although it does not match their age-metallicty relationship, nor those of MW globular clusters formed in-situ or ex-situ, nor that of LMC clusters either, but is in agreement with that of SMC old star clusters. We performed numerical Monte Carlo simulations integrating its orbital motion backward in the MW-LMC-SMC system with radially extended dark matter haloes that experience dynamical friction, and by exploring different radial velocity (RV) regimes for YMCA-1. For RVs $\gtrsim$ 300 km/s, the cluster remains bound to the LMC during the last 500 Myrs. The detailed tracked kinematic of YMCA-1 suggests that its could have been stripped by the LMC from the SMC during any of the close interactions between both galaxies, a scenario previously predicted by numerical simulations.

In this paper, we calculate the analytical solutions for the radii of planar and polar spherical photon orbits around a rotating black hole that is associated with quintessential field and cloud of strings. This includes a full analytical treatment of a quintic that describes orbits on the equatorial plane. Furthermore, The radial profile of the impact parameters is studied and the radii corresponding to the extreme cases are derived. For the more general cases, we also discuss the photon regions that form around this black hole. To simulate the orbits that appear in different inclinations, we analytically solve the latitudinal and azimuth equations of motion in terms of the Weierstrassian elliptic functions, by considering the radii of spherical orbits, in their general form, as the initial conditions. The period and the stability conditions of the orbits are also obtained analytically.

Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints we construct a novel, scale-independent description of the sound speed in neutron stars where the latter is expressed in a unit-cube spanning the normalised radius, $r/R$, and the mass normalized to the maximum one, $M/M_{\rm TOV}$. From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, respectively, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with $M/M_{\rm TOV}\gtrsim0.7$, reaching a constant value of $c_s^2=1/2$ as $M\to M_{\rm TOV}$. We also show that the sound speed decreases below the conformal limit $c_s^2=1/3$ at the center of stars with $M=M_{\rm TOV}$. Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.

We note that the decoherence of inflationary curvature perturbation $\zeta$ is dominated by a boundary term of the gravity action. Although this boundary term cannot affect cosmological correlators $\left\langle \zeta^n \right\rangle$, it induces much faster decoherence for $\zeta$ than that of previous calculations. The gravitational origin of inflationary decoherence sheds light on the quantum (or non-classical) nature of gravity. By comparing with a Schr\"odinger-Newton toy model of classical gravity, we show that gravity theories of classical or quantum origins can be distinguished by comparing their different impacts on decoherence rate of $\zeta$. Our calculation also indicates that density fluctuation $\delta\rho$ better preserves quantum information than $\zeta$ for the purpose of constructing cosmological Bell-like experiments.

We study the heat transfer in weakly interacting particle systems in vacuum. The particles have surface roughness with self-affine fractal properties, as expected for mineral particles produced by fracture, e.g., by crunching brittle materials in a mortar. We show that the propagating electromagnetic (EM) waves and the evanescent EM-waves, which occur outside of all solids, give the dominant heat transfer for large and small particles, respectively, while the phononic contribution from the area of real contact is negligible. As an application we discuss the heat transfer in rubble pile asteroids.

The interaction of neutrino transition magnetic dipole moments with magnetic fields can give rise to the phenomenon of neutrino spin-flavour precession (SFP). For Majorana neutrinos, the combined action of SFP of solar neutrinos and flavour oscillations would manifest itself as a small, yet potentially detectable, flux of electron antineutrinos coming from the Sun. Non-observation of such a flux constrains the product of the neutrino magnetic moment $\mu$ and the strength of the solar magnetic field $B$. We derive a simple analytical expression for the expected $\bar{\nu}_e$ appearance probability in the three-flavour framework and we use it to revisit the existing experimental bounds on $\mu B$. A full numerical calculation has also been performed to check the validity of the analytical result. We also present our numerical results in energy-binned form, convenient for analyses of the data of the current and future experiments searching for the solar $\bar{\nu}_e$ flux. In addition, we give a comprehensive compilation of other existing limits on neutrino magnetic moments and of the expressions for the probed effective magnetic moments in terms of the fundamental neutrino magnetic moments and leptonic mixing parameters.

The measurement of the inflationary stochastic gravitational-wave background (SGWB) is one of the main goals of future GW experiments. In direct GW experiments, an obstacle to achieving it is the isolation of the inflationary SGWB from the other types of SGWB. In this paper, as a distinguishable signature of the inflationary SGWB, we argue the detectability of its universal property: antipodal correlations, i.e., correlations of GWs from the opposite directions, as a consequence of the horizon re-entry. A phase-coherent method has been known to be of no use to detect the angular correlations in SGWB due to a problematic phase factor. We thus investigate whether we can construct a phase-incoherent estimator of the antipodal correlations in the intensity map. We find that, unfortunately, the answer is no: there is no estimator that is sensitive to the antipodal correlations but does not suffer from the problematic phase factor. Our analysis clarifies the importance of averaging in defining the estimator and will give an insight on what kind of angular correlations in SGWB is detectable or not.

Mega-constellations in Low Earth Orbit have the potential to revolutionise worldwide internet access. The concomitant potential of these mega-constellations to impact space sustainability, however, has prompted concern from space actors as well as provoking concern in the ground-based astronomy community. Increasing the knowledge of the orbital state of satellites in mega-constellations improves space situations awareness, reducing the need for collision avoidance manoeuvres and allowing astronomers to prepare better observational mitigation strategies. In this paper, we create a model of Phase 1 of Starlink, one of the more well-studied megaconstellations, and investigate the potential of cooperative localisation using time-ofarrival measurements from the optical inter-satellite links in the constellation. To this end, we study the performance of any unbiased estimator for localisation, by calculating the instantaneous Cram$\acute{\text{e}}$r-Rao bound for two situations; one in which inter-satellite measurements and measurements from ground stations were considered, and one in which only relative navigation from inter-satellite measurements were considered. Our results show that localisation determined from a combination of inter-satellite measurements and ground stations can have at best an an average RMSE of approximately 10.15 metres over the majority of a satellite's orbit. Relative localisation using only inter-satellite measurements has a slightly poorer performance with an average RMSE of 10.68 metres. The results show that both anchored and anchorless inter-satellite cooperative localisation are dependent on the constellation's geometry and the characteristics of the inter-satellite links, both of which could inform the use of relative navigation in large satellite constellations in future.

All scientific claims of gravitational wave discovery to date rely on the offline statistical analysis of candidate observations in order to quantify significance relative to background processes. The current foundation in such offline detection pipelines in experiments at LIGO is the matched-filter algorithm, which produces a signal-to-noise-ratio-based statistic for ranking candidate observations. Existing deep-learning-based attempts to detect gravitational waves, which have shown promise in both signal sensitivity and computational efficiency, output probability scores. However, probability scores are not easily integrated into discovery workflows, limiting the use of deep learning thus far to non-discovery-oriented applications. In this paper, the Deep Learning Signal-to-Noise Ratio (DeepSNR) detection pipeline, which uses a novel method for generating a signal-to-noise ratio ranking statistic from deep learning classifiers, is introduced, providing the first foundation for the use of deep learning algorithms in discovery-oriented pipelines. The performance of DeepSNR is demonstrated by identifying binary black hole merger candidates versus noise sources in open LIGO data from the first observation run. High-fidelity simulations of the LIGO detector responses are used to present the first sensitivity estimates of deep learning models in terms of physical observables. The robustness of DeepSNR under various experimental considerations is also investigated. The results pave the way for DeepSNR to be used in the scientific discovery of gravitational waves and rare signals in broader contexts, potentially enabling the detection of fainter signals and never-before-observed phenomena.

We develop a multiscale approach to estimate high-dimensional probability distributions from a dataset of physical fields or configurations observed in experiments or simulations. In this way we can estimate energy functions (or Hamiltonians) and efficiently generate new samples of many-body systems in various domains, from statistical physics to cosmology. Our method -- the Wavelet Conditional Renormalization Group (WC-RG) -- proceeds scale by scale, estimating models for the conditional probabilities of "fast degrees of freedom" conditioned by coarse-grained fields. These probability distributions are modeled by energy functions associated with scale interactions, and are represented in an orthogonal wavelet basis. WC-RG decomposes the microscopic energy function as a sum of interaction energies at all scales and can efficiently generate new samples by going from coarse to fine scales. Near phase transitions, it avoids the "critical slowing down" of direct estimation and sampling algorithms. This is explained theoretically by combining results from RG and wavelet theories, and verified numerically for the Gaussian and $\varphi^4$ field theories. We show that multiscale WC-RG energy-based models are more general than local potential models and can capture the physics of complex many-body interacting systems at all length scales. This is demonstrated for weak-gravitational-lensing fields reflecting dark matter distributions in cosmology, which include long-range interactions with long-tail probability distributions. WC-RG has a large number of potential applications in non-equilibrium systems, where the underlying distribution is not known {\it a priori}. Finally, we discuss the connection between WC-RG and deep network architectures.

In the framework of mixed Higgs-Starobinsky inflation, we consider the generation of Abelian gauge fields due to their nonminimal coupling to gravity (in two different formulations of gravity -- metric and Palatini). We couple the gauge-field invariants $F_{\mu\nu}F^{\mu\nu}$ and $F_{\mu\nu}\tilde{F}^{\mu\nu}$ to an integer power of the scalar curvature $R^n$ in Jordan frame and, treating these interactions perturbatively, switch to the Einstein frame where they lead to effective kinetic and axial couplings between gauge fields and inflaton. We determine the power spectra, energy densities, correlation length, and helicality of the generated gauge fields for different values of the nonminimal coupling constants and parameter $n$. We analytically estimate the spectral index $n_{B}$ of the magnetic power spectrum and show that for $n>1$ it is possible to get the scale-invariant or even red-tilted spectrum for a wide range of modes that implies larger correlation length of the generated fields. On the other hand, the magnitude of these fields typically decreases in time becoming very small in the end of inflation. Thus, it is difficult to obtain both large magnitude and correlation length of the gauge field in the frame of this model.