Papers for Monday, Mar 14 2022

With recent advances in the sensitivity of radio surveys of the Galactic disk, the number of millisecond pulsars (MSPs) has increased substantially in recent years such that it is now possible to study their demographic properties in more detail than in the past. We investigate what can be learned about the radio spectra of the MSP population. Using a sample of 179 MSPs detected in eleven surveys carried out at radio frequencies in the range 0.135-6.6 GHz, we carry out detailed modeling of MSP radio spectral behaviour in this range. Employing Markov Chain Monte Carlo simulations to explore a multi-dimensional parameter space, and accurately accounting for observational selection effects, we find strong evidence in favour of the MSP population having a two-component power-law spectral model scaling with frequency, $\nu$. Specifically, we find that MSP flux density spectra are approximately independent of frequency below 320 MHz, and proportional to $\nu^{-1.5}$ at higher frequencies. This parameterization performs significantly better than single power-law models which over predict the number of MSPs seen in low-frequency (100-200 MHz) surveys. We compared our results with earlier work, and current understanding of the normal pulsar population, and use our model to make predictions for MSP yields in upcoming surveys. We demonstrate that the observed sample of MSPs could triple in the coming decade.

Single pulse behaviour of radio pulsars is usually interpreted in terms of the ExB drift of a radio beam. It is shown that antisymmetric arrangement of the radio-bright zones can produce several types of observed single pulse phenomena: the half-cycle jump in subpulse modulation phase, left-right-middle subpulse sequence and switching between the core-dominated and cone-dominated pulsation modes. The geometry can also produce nulling, both sporadic and intermodal. The model implies that the radio-quiet intervals that separate the main pulse and interpulse in PSR B0826-34 correspond to azimuthal breaks in the radio beam, instead of breaks in colatitude.

Bars may induce morphological features, such as rings, through their resonances. Previous studies suggested that the presence of 'dark-gaps', or regions of a galaxy where the difference between the surface brightness along the bar major axis and along the bar minor axis are maximal, can be attributed to the location of bar corotation. Here, using GALAKOS, a high-resolution N-body simulation of a barred galaxy, we test this photometric method's ability to identify the bar corotation resonance. Contrary to previous work, our results indicate that 'dark-gaps' are a clear sign of the location of the 4:1 ultra-harmonic resonance instead of bar corotation. Measurements of the bar corotation can indirectly be inferred using kinematic information, e.g., by measuring the shape of the rotation curve. We demonstrate our concept on a sample of 578 face-on barred galaxies with both imaging and integral field observations and find the sample likely consists primarily of fast bars.

We explore the characteristics of actively accreting MBHs within dwarf galaxies in the \textsc{Romulus25} cosmological hydrodynamic simulation. We examine the MBH occupation fraction, x-ray active fractions, and AGN scaling relations within dwarf galaxies of stellar mass $10^{8} < M_{\rm star} < 10^{10} M_\odot$ out to redshift $z=2$. In the local universe, the MBH occupation fraction is consistent with observed constraints, dropping below unity at $M_{\rm star} < 3\times10^{10} M_{\odot}$, $M_{\rm 200} < 3\times10^{11} M_\odot$. Local dwarf AGN in \textsc{Romulus25} follow observed scaling relations between AGN x-ray luminosity, stellar mass, and star formation rate, though they exhibit slightly higher active fractions and number densities than comparable x-ray observations. Since $z=2$, the MBH occupation fraction has decreased, the population of dwarf AGN has become overall less luminous, and as a result, the overall number density of dwarf AGN has diminished. We predict the existence of a large population of MBHs in the local universe with low x-ray luminosities and high contamination from x-ray binaries and the hot interstellar medium that are undetectable by current x-ray surveys. These hidden MBHs make up $76\%$ of all MBHs in local dwarf galaxies, and include many MBHs that are undermassive relative to their host galaxy's stellar mass. Their detection relies not only on greater instrument sensitivity but on better modeling of x-ray contaminants or multi-wavelength surveys. Our results indicate dwarf AGN were substantially more active in the past despite being low-luminosity today, and indicate future deep x-ray surveys may uncover many hidden MBHs in dwarf galaxies out to at least $z=2$.

We review the different approaches for combining the cosmological information from the full shape of the pre-reconstructed power spectrum - usually referred as redshift-space distortion (RSD) analysis - and from the baryon acoustic oscillation (BAO) peak position in the post-reconstructed power spectrum with the aim of finding the optimal procedure. We focus on combining the pre- and post-reconstructed derived quantities at different compression levels: 1) the two-point summary statistics, the power spectrum multipoles, $P^{(\ell)}(k)$; 2) the compressed BAO variables, $\alpha_{\parallel,\perp}$; and 3) an hybrid approach between 1) and 2). We apply these methods to the publicly available eBOSS Luminous Red Galaxy catalogues, for both data and synthetic EZ-mocks. We find that the three approaches result in very consistent posteriors when the appropriate covariance matrix estimator is used. On average, the combination at $P^{(\ell)}(k)$ level retrieves $\lesssim10\%$ tighter constraints than the other two approaches, demonstrating that the standard approach of compressing before combining is nearly optimal. After checking for potential systematics, such as, the way the matrix is built and the effect of the finite number of mock on the likelihood estimator, we conclude that combining both BAO and full shape signals for the one single data realization at the level of the summary statistics is faster and brings a moderate $10\%$ improvement, with respect to the other two studied methods. Moreover we find that this method has no additional systematics when the already existing techniques in the literature are employed.

Bayesian posterior inference of modern multi-probe cosmological analyses incurs massive computational costs. For instance, depending on the combinations of probes, a single posterior inference for the Dark Energy Survey (DES) data had a wall-clock time that ranged from 1 to 21 days using a state-of-the-art computing cluster with 100 cores. These computational costs have severe environmental impacts and the long wall-clock time slows scientific productivity. To address these difficulties, we introduce LINNA: the Likelihood Inference Neural Network Accelerator. Relative to the baseline DES analyses, LINNA reduces the computational cost associated with posterior inference by a factor of 8--50. If applied to the first-year cosmological analysis of Rubin Observatory's Legacy Survey of Space and Time (LSST Y1), we conservatively estimate that LINNA will save more than US $\$300,000$ on energy costs, while simultaneously reducing $\rm{CO}_2$ emission by $2,400$ tons. To accomplish these reductions, LINNA automatically builds training data sets, creates neural network surrogate models, and produces a Markov chain that samples the posterior. We explicitly verify that LINNA accurately reproduces the first-year DES (DES Y1) cosmological constraints derived from a variety of different data vectors with our default code settings, without needing to retune the algorithm every time. Further, we find that LINNA is sufficient for enabling accurate and efficient sampling for LSST Y10 multi-probe analyses. We make LINNA publicly available at https://github.com/chto/linna, to enable others to perform fast and accurate posterior inference in contemporary cosmological analyses.

Galactic chemical evolution (GCE), solar analogues or twins, and peculiarities of the solar composition with respect to the twins are inextricably related. We examine GCE parameters from the literature and present newly derived values using a quadratic fit that gives zero for a Solar age (i.e., 4.6 Gyr). We show how the GCE parameters may be used not only to "correct" abundances to the solar age, but to predict relative elemental abundances as a function of age. We address the question of whether the solar abundances are depleted in refractories and enhanced in volatiles and find that the answer is sensitive to the selection of a representative standard. The best quality data sets do not support the notion that the Sun is depleted in refractories and enhanced in volatiles. A simple model allows us to estimate the amount of refractory-rich material missing from the Sun or alternately added to the average solar twin. The model gives between zero and 1.4 earth masses.

The MOND paradigm is an empirical theory with modified gravity to reproduce many astronomical observations without invoking the dark matter hypothesis. Instead of falsifying the existence of dark matter, we propose that MOND is an effective theory naturally emerging from the long-range and collisionless nature of dark matter flow. It essentially describes the dynamics of baryonic mass suspended in fluctuating dark matter fluid. We first review the unique properties of self-gravitating collisionless dark matter flow (SG-CFD), followed by their implications in the origin of MOND theory. To maximize system entropy, the long-range interaction requires a broad size of halos to be formed. These halos facilitate an inverse mass and energy cascade from small to large mass scales that involves a constant rate of energy transfer $\epsilon_u$=$-4.6\times10^{-7}m^2/s^3$. In addition to the velocity fluctuation with a typical scale $u$, the long-range interaction leads to a fluctuation in acceleration with a typical scale $a_0$ that matches the value of critical MOND acceleration. The velocity and acceleration fluctuations in dark matter flow satisfy the equality $\epsilon_u$=$-a_0u/(3\pi)^2$ such that $a_0$ can be determined. A notable (unexplained) coincidence of cosmological constant $\Lambda\propto (a_0/c)^2$ might point to a dark energy density proportional to acceleration fluctuation, i.e. $\rho_{vac}\propto a_0^2/G$. At z=0 with $u$=354.61km/s, $a_0$=$1.2\times10^{-10}m/s^2$ can be obtained. For given particle velocity $v_p$, maximum entropy distributions developed from mass/energy cascade lead to a particle kinetic energy $\epsilon_k\propto v_p$ at small acceleration $<a_0$ and $\epsilon_k\propto v_p^2$ for large acceleration $>a_0$. Combining this with the constant rate of energy transfer $\epsilon_u$, both regular Newtonian dynamics and deep-MOND behavior can be fully recovered.

Using the exquisite MUSE eXtremely Deep Field data, we report the discovery of an MgII emission nebula with an area above a 2$\sigma$ significance level of 1000 proper kpc$^2$, providing the first panoramic view of the spatial distribution of magnesium in the intragroup medium of a low mass group of five star-forming galaxies at z=1.31. The galaxy group members are separated by less than 50 physical kpc in projection and $\approx$120 km/s in velocity space. The most massive galaxy has a stellar mass of 10$^{9.35}$ M$_\odot$ and shows an MgII P-Cygni line profile indicating the presence of an outflow, which is consistent with the spatially resolved spectral analysis showing $\approx+$120 km/s shift of the MgII emission lines with respect to the systemic redshift. The other galaxies are less massive and only show MgII in emission. The detected MgII nebula has a maximal projected extent of $\approx$70 kpc including a low surface brightness (2 $\times$ 10$^{-19}$ erg/s/cm$^{2}$/arcsec$^{2}$) gaseous bridge between two subgroups of galaxies. The presence of absorption features in the spectrum of a background galaxy located at an impact parameter of 19 kpc from the closest galaxy of the group indicates the presence of gas enriched in magnesium even beyond the detected nebula seen in emission, suggesting that we are observing the tip of a larger intragroup medium. The observed MgII velocity gradient suggests an overall rotation of the structure along the major axis of the most massive galaxy. Our MUSE data also reveal extended Fe II* emission in the vicinity of the most massive galaxy, aligned with its minor axis. Extended [OII] emission is found around the galaxy group members and at the location of the MgII bridge. Our results suggest that both tidal stripping effects from galaxy interactions and outflows are enriching the intragroup medium of this system.

Galaxy clusters are important cosmological probes since their abundance and spatial distribution are directly linked to structure formation on large scales. The principal uncertainty source on the cosmological parameter constraints concerns the cluster mass estimation from mass proxies. In addition, future surveys will provide a large amount of data, requiring an improvement in the accuracy of other elements used in the construction of cluster likelihoods. Therefore, accurate modeling of the mass-observable relations and reducing the effect of different systematic errors are fundamental steps for the success of cluster cosmology. In this work, we briefly review the abundance of galaxy clusters and discuss many sources of uncertainty. Os aglomerados de gal\'axias s\~ao importantes sondas cosmol\'ogicas, j\'a que a abund\^ancia e a distribui\c{c}\~ao espacial desses objetos est\~ao diretamente ligadas \`a forma\c{c}\~ao de estruturas em grandes escalas. A maior fonte de incerteza nas restri\c{c}\~oes de par\^ametros cosmol\'ogicos \'e origin\'aria das estimativas das massas dos aglomerados a partir da rela\c{c}\~ao massa-observ\'avel. Al\'em disso, os pr\'oximos grandes levantamentos fornecer\~ao uma grande quantidade de dados, requerendo uma melhoria na precis\~ao de outros elementos utilizados na constru\c{c}\~ao das verossimilhan\c{c}as de aglomerados. Portanto, uma modelagem precisa da rela\c{c}\~ao massa-observ\'avel e diminuir o efeito dos diferentes erros sistem\'aticos s\~ao passos fundamentais para o sucesso da cosmologia com aglomerados. Neste trabalho, fazemos uma breve revis\~ao da abund\^ancia de aglomerados de gal\'axias, e discuss\~ao de diferentes fontes de incerteza.

We report the detection of the protonated form of HC7N in TMC-1. The discovery of the cation HC7NH+ was carried out via the observation of nine harmonically related lines in the Q-band using the Yebes 40m radiotelescope. The observed frequencies allowed us to obtain the rotational constants B_0=553.938802(160)MHz and D_0=3.6292(705) Hz. The identification of HC7NH+ is further supported by accurate ab initio calculations. We derived a column density of (5.5+/-0.7)e10 cm-2, which constitutes another piece of evidence for the identification of the carrier. In addition, we revised the HC7N column density and we derived a new value of (2.1+/-0.2)e13cm-2. Hence, the abundance ratio HC7N/HC7NH+ is 380, while those for HC3N/HC3NH+ and HC5N/HC5NH+ are 230 and 240, respectively. Here, we discuss these results within the framework of a chemical model for protonated molecules in cold dense clouds.

Rings and gaps are commonly observed in the dust continuum emission of young stellar disks. Previous studies have shown that substructures naturally develop in the weakly ionized gas of magnetized, non-ideal MHD disks. The gas rings are expected to trap large mm/cm-sized grains through pressure gradient-induced radial dust-gas drift. Using 2D (axisymmetric) MHD simulations that include ambipolar diffusion and dust grains of three representative sizes (1~mm, 3.3~mm, and 1~cm), we show that the grains indeed tend to drift radially relative to the gas towards the centers of the gas rings, at speeds much higher than in a smooth disk because of steeper pressure gradients. However, their spatial distribution is primarily controlled by meridional gas motions, which are typically much faster than the dust-gas drift. In particular, the grains that have settled near the midplane are carried rapidly inwards by a fast accretion stream to the inner edges of the gas rings, where they are lifted up by the gas flows diverted away from the midplane by a strong poloidal magnetic field. The flow pattern in our simulation provides an attractive explanation for the meridional flows recently inferred in HD 163296 and other disks, including both "collapsing" regions where the gas near the disk surface converges towards the midplane and a disk wind. Our study highlights the prevalence of the potentially observable meridional flows associated with the gas substructure formation in non-ideal MHD disks and their crucial role in generating rings and gaps in dust.

The Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is a proposed space telescope with a 14 m inflatable primary reflector that will perform high spectral resolution observations at terahertz frequencies with heterodyne receivers. The telescope consists of an inflatable metallized polymer membrane that serves as the primary antenna, followed by aberration correction optics, and a scanner that enables a 0.1 degrees Field of Regards while achieving diffraction limited performance over wavelength range from 63 to 660 {\mu}m. Here the parametric solution space of the OASIS inflatable telescope design is systematically investigated by establishing analytical relations among figure of merits including 1st order geometrical photon collection area and the size of correction optics. The 1st order solution was further optimized by ray-trace code by incorporating numerically calculated mirror shape with pre-formed membrane gores. Design study shows that a space-based telescope with an effective photon collection area of over 90m2 can be achieved utilizing a 14m inflatable aperture.

We surveyed a sample of compact Galactic planetary nebulae (PNe) with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST/STIS) to determine their gas-phase carbon abundances. Carbon abundances in PNe constrain the nature of their asymptotic giant branch (AGB) progenitors, as well as cosmic recycling. We measured carbon abundances, or limits thereof, of 11 compact Galactic PNe, notably increasing the sample of Galactic PNe whose carbon abundance based on HST ultraviolet spectra is available. Dust content of most targets has been studied elsewhere from Spitzer spectroscopy; given the compact nature of the nebulae, both UV and IR spectra can be directly compared to study gas- and dust-phase carbon. We found that carbon-poor (C/O<1) compact Galactic PNe have oxygen-rich dust type (ORD), while their carbon-enhanced counterparts (C/O>1) have carbon-rich dust (CRD), confirming the correlation between gas- and dust-phase carbon content which was known for Magellanic Cloud PNe. Based on models of expected final yields from AGB evolution we interpret the majority of the carbon-poor PNe in this study as the progeny of ~1.1-1.2 M$_{\odot}$ stars that experienced some extra-mixing on the red giant branch (RGB), they went through the AGB but did not go through the carbon star phase. Most PNe in this group have bipolar morphology, possibly due to the presence of a sub-solar companion. Carbon-enhanced PNe in our sample could be the progeny of stars in the ~1.5-2.5 M$_{\odot}$ range, depending on their original metallicity.

Intense flares at cm-wavelengths reaching levels of tens of Jy have been observed from Cygnus X-3 for many years. This active high mass X-ray binary also has periods of quenching before major outbursts, and has minor flares at levels of a few hundred mJy. In this paper we show that the minor flares have much shorter rise times and durations suggesting more rapid expansion of the synchrotron radiation emitting material than in the strong flares. They also appear closer to the binary, whereas the large flares form a more developed jet. Calculations of physical conditions show that the minor out-bursts have lower minimum power but have larger magnetic fields and energy densities than the major flares. Minor flares can occur while a major flare is in progress, suggesting an indirect coupling between them. The spectral evolution of the minor flares can be explained by either an expanding synchrotron source or a shock model. The possibility that there is a brightening zone as in SS433 is explored.

Observations with the Fermi Large Area Telescope (LAT) of the gamma-ray source 4FGL J1702.7-5655, previously classified as a candidate millisecond pulsar, show highly-significant modulation at a period of 0.2438033 days (~ 5.85 hours). Further examination of the folded light curve indicates the presence of narrow eclipses, suggesting this is a redback binary system. An examination of the long-term properties of the modulation over 13 years of LAT observations indicates that the orbital modulation of the gamma-rays changed from a simple eclipse before early 2013, to a broader, more easily detected, quasi-sinusoidal modulation. In addition, the time of the eclipse shifts to ~0.05 later in phase. This change in the orbital modulation properties is, however, not accompanied by a significant overall change in gamma-ray flux or spectrum. The quasi-sinusoidal component peaks ~0.5 out of phase with the eclipse, which would indicate inferior conjunction of the compact object in the system. Swift X-ray Telescope observations reveal a possible X-ray counterpart within the LAT error ellipse. However, radio observations obtained with the Australia Telescope Compact Array do not detect a source in the region. 4FGL J1702.7-5655 appears to have changed its state in 2013, perhaps related to changes in the intrabinary shock in the system. We discuss how the properties of 4FGL J1702.7-5655 compare to other binary millisecond pulsars that have exhibited orbital modulation in gamma rays.

We analyze stellar proper motions in the COSMOS field to assess the presence of bulk motions. At bright magnitudes (G-band 18.5--20.76 AB), we use the proper motions of 1,010 stars in the Gaia DR2 catalog. At the faint end, we computed proper motions of 11,519 point-like objects at i-band magnitudes 19--25 AB using Hubble ACS and Subaru HSC, which span two epochs about 11 years apart. In order to measure these proper motions with unprecedented accuracy at faint magnitudes, we developed a foundational set of astrometric tools which will be required for Joint Survey Processing (JSP) of data from the next generation of optical/infrared surveys. The astrometric grids of Hubble ACS and Subaru HSC mosaics were corrected at the catalog level, using proper motion-propagated and parallax-corrected Gaia DR2 sources. These astrometric corrections were verified using compact extragalactic sources. Upon comparison of our measured proper motions with Gaia DR2, we estimate the uncertainties in our measurements to be ~2--3 mas/yr per axis, down to 25.5 AB mag. We corrected proper motions for the mean motion of the Sun, and we find that late-type main-sequence stars predominantly in the thin disk in the COSMOS field have space velocities mainly towards the Galactic center. We detect candidate high-velocity (> 220 km/s) stars, 6 of them at ~0.4-6 kpc from the Gaia sample, and 5 of them at ~20 kpc from the faint star HSC and ACS sample. The sources from the faint star sample may be candidate halo members of the Sangarius stream.

Although the main goal of the Transiting Exoplanet Survey Satellite (\textit{TESS}) is to search for new transiting exoplanets, its data can also be used to study in further detail already known systems. The \textit{TESS} bandpass is particularly interesting to study the limb-darkening effect of the stellar host which is imprinted in transit lightcurves, as the widely used \textsc{phoenix} and \textsc{atlas} stellar models predict different limb-darkening profiles. Here we study this effect by fitting the transit lightcurves of 176 known exoplanetary systems observed by \textit{TESS}, which allows us to extract empirical limb-darkening coefficients (LDCs) for the widely used quadratic law, but also updated transit parameters (including ephemerides refinements) as a byproduct. Comparing our empirically obtained LDCs with theoretical predictions, we find significant offsets when using tabulated \textit{TESS} LDCs. Specifically, the $u_2$ coefficients obtained using \textsc{phoenix} models show the largest discrepancies depending on the method used to derive them, with offsets that can reach up to $\Delta u_2 \approx 0.2$ on average. Most of those average offsets disappear, however, if one uses the SPAM algorithm introduced by Howarth (2011) to calculate the LDCs instead. Our results suggest, however, that for stars cooler than about 5000 K, no methodology is good enough to explain the limb-darkening effect: we observe a sharp deviation between measured and predicted LDCs on both quadratic LDCs of order $\Delta u_1, \Delta u_2 \approx 0.2$ for those cool stars. We recommend caution when assuming limb-darkening coefficients as perfectly known thus, in particular for these cooler stars when analyzing \textit{TESS} transit lightcurves.

CMB-HD is a proposed millimeter-wave survey over half the sky that would be ultra-deep (0.5 uK-arcmin) and have unprecedented resolution (15 arcseconds at 150 GHz). Such a survey would answer many outstanding questions about the fundamental physics of the Universe. Major advances would be 1.) the use of gravitational lensing of the primordial microwave background to map the distribution of matter on small scales (k~10 h Mpc^(-1)), which probes dark matter particle properties. It will also allow 2.) measurements of the thermal and kinetic Sunyaev-Zel'dovich effects on small scales to map the gas density and velocity, another probe of cosmic structure. In addition, CMB-HD would allow us to cross critical thresholds: 3.) ruling out or detecting any new, light (< 0.1 eV) particles that were in thermal equilibrium with known particles in the early Universe, 4.) testing a wide class of multi-field models that could explain an epoch of inflation in the early Universe, and 5.) ruling out or detecting inflationary magnetic fields. CMB-HD would also provide world-leading constraints on 6.) axion-like particles, 7.) cosmic birefringence, 8.) the sum of the neutrino masses, and 9.) the dark energy equation of state. The CMB-HD survey would be delivered in 7.5 years of observing 20,000 square degrees of sky, using two new 30-meter-class off-axis crossed Dragone telescopes to be located at Cerro Toco in the Atacama Desert. Each telescope would field 800,000 detectors (200,000 pixels), for a total of 1.6 million detectors.

The properties of young star clusters formed within a galaxy are thought to vary in different interstellar medium (ISM) conditions, but the details of this mapping from galactic to cluster scales are poorly understood due to the large dynamic range involved in galaxy and star cluster formation. We introduce a new method for modeling cluster formation in galaxy simulations: mapping giant molecular clouds (GMCs) formed self-consistently in a FIRE-2 MHD galaxy simulation onto a cluster population according to a GMC-scale cluster formation model calibrated to higher-resolution simulations, obtaining detailed properties of the galaxy's star clusters in mass, metallicity, space, and time. We find $\sim 10\%$ of all stars formed in the galaxy originate in gravitationally-bound clusters overall, and this fraction increases in regions with elevated $\Sigma_{\rm gas}$ and $\Sigma_{\rm SFR}$, because such regions host denser GMCs with higher star formation efficiency. These quantities vary systematically over the history of the galaxy, driving variations in cluster formation. The mass function of bound clusters varies -- no single Schechter-like or power-law distribution applies at all times. In the most extreme episodes, clusters as massive as $7\times 10^6 M_\odot$ form in massive, dense clouds with high star formation efficiency. The initial mass-radius relation of young star clusters is consistent with an environmentally-dependent 3D density that increases with $\Sigma_{\rm gas}$ and $\Sigma_{\rm SFR}$. The model does not reproduce the age and metallicity statistics of old ($>11\rm Gyr$) globular clusters found in the Milky Way, possibly because it forms stars more slowly at $z>3$.

Primordial black holes (PBHs) lose mass by Hawking evaporation. For sufficiently small PBHs, they may lose a large portion of their formation mass by today, or even evaporate completely if they form with mass $M<M_{\mathrm{crit}}\sim5\times10^{14}~\mathrm{g}$. We investigate the effect of this mass loss on extended PBH distributions, showing that the shape of the distribution is significantly changed between formation and today. We reconsider the $\gamma$-ray constraints on PBH dark matter in the Milky Way center with a correctly `evolved' lognormal distribution, and derive a semi-analytic time-dependent distribution which can be used to accurately project monochromatic constraints to extended distribution constraints. We also derive the rate of black hole explosions in the Milky Way per year, finding that although there is a significant number, it is extremely unlikely to find one close enough to Earth to observe. Along with a more careful argument for why monochromatic PBH distributions are unlikely to source an exploding PBH population today, we (unfortunately) conclude that we are unlikely to witness any PBH explosions.

We use observations of ultra-faint dwarf (UFD) galaxies to constrain the particle mass of ultra-light dark matter. Potential fluctuations created by wave interference in virialized "fuzzy" dark matter (FDM) halos dynamically heat stellar orbits in UFDs, some of which exhibit velocity dispersions of $\lesssim$ 3 km/s and sizes $\lesssim$ 40 pc. Using simulations of FDM halos, and existing measurements of sizes and stellar radial velocities in Segue 1 and Segue 2 UFDs, we derive a lower limit on the dark matter particle mass of $m_{fdm} > 3\times 10^{-19}$ eV at 99% confidence, marginalized over host halo circular velocity. This constraint is conservative as it is derived under the assumption that soliton heating is negligible, and that no other sources of non-FDM dynamical heating of stars operate to increase velocity dispersion. It can potentially be strengthened by future spectroscopic observations of additional stars in ultra-faint galaxies and by tightening theoretical constraints on the soliton size-halo mass relation. However, even the current conservative lower limit on the FDM mass makes this model indistinguishable from Cold Dark Matter at the scales probed by existing astronomical observations.

Solar activity has significant impacts on human activities and health. One most commonly used measure of solar activity is the sunspot number. This paper compares three important non-deep learning models, four popular deep learning models, and their five ensemble models in forecasting sunspot numbers. Our proposed ensemble model XGBoost-DL, which uses XGBoost as a two-level nonlinear ensemble method to combine the deep learning models, achieves the best forecasting performance among all considered models and the NASA's forecast. Our XGBoost-DL forecasts a peak sunspot number of 133.47 in May 2025 for Solar Cycle 25 and 164.62 in November 2035 for Solar Cycle 26, similar to but later than the NASA's at 137.7 in October 2024 and 161.2 in December 2034.

We analysed observations with XMM-Newton in the field of the Sculptor dwarf spheroidal galaxy (dSph). The aim of the study was the classification of X-ray binaries and accreting white dwarfs, which belong to the Sculptor dSph. Using different methods of X-ray timing and spectral analyses, together with an extensive multi-wavelength study of the optical and infrared counterparts of the X-ray sources, we classified the sources detected with XMM-Newton in the field of Sculptor dSph. The long term variability of the sources has been studied over two \xmm\, observations. None of the members of Sculptor dSph show a significant long-term variability over these two observations. We also searched for periodicity and pulsation using the Lomb-Scargle and Rayleigh's Z_n^2 techniques. No signal of pulsation or periodicity have been found for the X-ray sources. The results show the presence of a noticeable number of background X-ray sources in the field of this galaxy. We classified 43 sources as active galactic nuclei (AGNs), galaxies, and galaxy candidates. Three Galactic foreground stars have been identified in the field of Sculptor dSph, and one of them is an M-dwarf candidate. Moreover, we classified four symbiotic star candidates and three quiescent low-mass X-ray binary candidates in Sculptor dSph. The luminosity of these X-ray sources is 10^{33-35} erg/s.

The recent advances in the flight capability of remotely piloted aerial vehicles (here after referred to as UAVs) have afforded the astronomical community the possibility of a new telescope calibration technique: UAV-based calibration. Building upon a feasibility study which characterised the potential that a UAV-based calibration system has for the future Cherenkov Telescope Array, we created a first-generation UAV-calibration prototype and undertook a field-campaign of inter-calibrating the sensitivity of the H.E.S.S. telescope array with two successful calibration flights. In this paper we report the key results of our first test campaign: firstly, by comparing the intensity of the UAV-calibration events, as recorded by the individual HESS-I cameras, we find that a UAV-based inter-calibration is consistent with the standard muon inter-calibration technique at the level of \SI{5.4}{\%} and \SI{5.8}{\%} for the two individual UAV-calibration runs. Secondly, by comparing the position of the UAV-calibration signal on the camera focal plane, for a variety of telescope pointing models, we were able to constrain the pointing accuracy of the HESS-I telescopes at the tens of arc-second accuracy level. This is consistent with the pointing accuracy derived from other pointing calibration methods. Importantly both the inter-calibration and pointing accuracy results were achieved with a first-generation UAV-calibration prototype, which eludes to the potential of the technique and highlights that a UAV-based system is a viable calibration technique for current and future ground-based $\gamma$-ray telescope arrays.

The two neutron star-black hole mergers (GW200105 and GW200115) observed in gravitational waves by advanced LIGO and Virgo, mark the first ever discovery of such binaries in nature. We study these two neutron star-black hole systems through isolated binary evolution, using a grid of population synthesis models. Using both mass and spin observations (chirp mass, effective spin and remnant spin) of the binaries, we probe their different possible formation channels in different metallicity environments. Our models only support LIGO data when assuming the black hole is non spinning. Our results show a strong preference that GW200105 and GW200115 formed from stars with sub-solar metallicities $Z\lesssim 0.005$. Only two metal-rich ($Z=0.02$) models are in agreement with GW200115. We also find that chirp mass and remnant spins jointly aid in constraining the models, whilst the effective spin parameter does not add any further information.

In order to understand the evolution and feedback of Active Galactic Nuclei (AGN) and star formation it is important to use molecular lines as probes of physical conditions and chemistry. We use H$_{2}$S to investigate the impact of starburst and AGN activity on the chemistry of the molecular interstellar medium in luminous infrared galaxies. Using the APEX single dish telescope, we have observed the $1_{10}$--$1_{01}$ transition of ortho-H$_{2}$S at 168 GHz towards the centres of twelve nearby luminous infrared galaxies. We have also observed the same line towards the ultra luminous infrared galaxy (ULIRG) Mrk~231 with the NOEMA interferometer. We have detected H$_{2}$S towards NGC~253, NGC~1068, NGC~3256, NGC~4418, NGC~4826, NGC~4945, Circinus, M~83 and Mrk~231. Four galaxies show elevated H$_{2}$S emission relative to HCN. We suggest that the high line ratios are caused by elevated H$_{2}$S abundances in the dense gas. However, we do not find any clear connection between the H$_{2}$S/HCN line intensity ratio, and the presence (or speed) of molecular outflows in the sample galaxies. Therefore H$_{2}$S abundances do not seem to be globally affected by the large-scale outflows. We discuss possible mechanisms behind the suggested H$_{2}$S abundance enhancements in NGC~4418, Circinus, NGC~3256 and NGC~4826. These include radiative processes (for example X-rays or cosmic-rays) or smaller scale shocks. We suggest that $L_{\mathrm{H_{2}S}}$ serves as a tracer of the dense gas content, similar to $L_{\mathrm{HCN}}$, and that the correlation between $L_{\mathrm{H_{2}S}}$ and $M_{\rm outflow}$(H$_2$) implies a relation between the dense gas reservoir and the properties and evolution of the molecular feedback. This potential link requires further study since it holds important keys to our understanding of how the properties of molecular outflows relate to that of their host galaxies.

We report on radio timing observations of the black widow binary pulsar J0610$-$2100 and optical observations of its binary companion. The radio timing observations extend the timing baseline to 16\,yr and reveal a marginal detection of the orbital period derivative, but they show no significant evidence of orbital variations such as those seen in other black widow pulsars. Furthermore, no eclipses are seen in the observations at observing frequencies ranging from 310 to 2700\,MHz. The optical $V\!RI$ light curves were modulated with the orbital period, reaching maximum brightness of $V=26.8$, $R=25.4$, and $I=23.8$ at superior conjunction of the companion, confirming irradiation of the companion by the pulsar. Modelling the light curves indicates that the companion is likely not filling its Roche lobe, while having a moderate inclination ($i > 54\degr$). We find an unusually low temperature and a low irradiation for the irradiated hemisphere of the companion. We investigate the absence of radio eclipses in PSR\,J0610$-$2100 and in other black widow systems in relation to their binary, pulsar, and companion properties. We also discuss the suitability of PSR\,J0610$-$2100 for pulsar timing array observations aimed at detecting nano-Hertz gravitational waves.

We identify Gaia0007-1605AC as the first inner brown dwarf-white dwarf binary of a hierarchical triple system in which the outer component is another white dwarf (Gaia0007-1605B). From optical/near-infrared spectroscopy obtained at the Very Large Telescope with the X-Shooter instrument and/or from Gaia photometry plus SED fitting, we determine the effective temperatures and masses of the two white dwarfs (12018+-68 K, 0.54+-0.01 Msun for Gaia0007-1605A and 4445+-116 K, 0.56+-0.05 Msun for Gaia0007-1605B) and the effective temperature of the brown dwarf (1850+-50 K; corresponding to a spectral type L3+-1). By analysing the available TESS light curves of Gaia0007-1605AC we detect a signal at 1.0446+-0.0015 days with an amplitude of 6.25 ppt, which we interpret as the orbital period modulated from irradiation effects of the white dwarf on the brown dwarf's surface. This drives us to speculate that the inner binary evolved through a common envelope phase in the past. Using the outer white dwarf as a cosmochronometer and analysing the kinematic properties of the system, we conclude that the triple system is about 10 Gyr old.

The origin of the Binary Black Hole (BBH) mergers detected through Gravitational Waves (GWs) by the LIGO-Virgo-KAGRA (LVK) collaboration remains debated. One fundamental reason is our ignorance of their host environment, as the typical size of an event's localization volume can easily contain thousands of galaxies. A strategy around this is to exploit statistical approaches to assess the spatial correlation between these mergers and astrophysically motivated host galaxy types, such as Active Galactic Nuclei (AGN). We use a Likelihood ratio method to infer the degree of GW-AGN connection out to $z=0.2$. We simulate BBH mergers whose components' masses are sampled from a realistic distribution of the underlying population of Black Holes (BHs). Localization volumes for these events are calculated assuming two different interferometric network configurations. These correspond to the configuration of the third (O3) and of the upcoming fourth (O4) LVK observing runs. We conclude that the 13 BBH mergers detected during the third observing run at $z\leq0.2$ are not enough to reject with a \(3\sigma\) significance the hypothesis according to which there is no connection between GW and AGN more luminous than $\approx 10^{44.3}\rm{erg}\ \rm{s}^{-1}$, that have number density higher than \(10^{-4.75}\textrm{Mpc}^{-3}\). However, 13 detections are enough to reject this no-connection hypothesis when rarer categories of AGN are considered, with bolometric luminosities greater than $\approx 10^{45.5}\rm{erg}\ \rm{s}^{-1}$. We estimate that O4 results will potentially allow us to test fractional contributions to the total BBH merger population from AGN of any luminosity higher than \(80\%\).

Breakthroughs in physics and astrophysics are often driven by technological advances, with the recent detection of gravitational waves being one such example. This white paper focuses upon how improved astrometric and spectroscopic measurements from a new generation of precise, accurate, and stable astronomical instrumentation can address two of the fundamental mysteries of our time -- dark energy and dark matter -- and probe the nature of spacetime. Instrumentation is now on the cusp of enabling new cosmological measurements based on redshifts (cosmic redshift drift) and extremely precise time-series measurements of accelerations, astrophysical source positions (astrometry), and angles (cosmic parallax). These allow tests of the fundamental framework of the universe (the Friedmann equations of general relativity and whether cosmic expansion is physically accelerating) and its contents (dark energy evolution and dark matter behavior), while also anchoring the cosmic distance scale ($H_0$).

Gamma-ray astronomy is still a rather young field of research, with strong historical connections to particle physics. This is why most observations are conducted by experiments with proprietary data and analysis software, as it is usual in the particle physics field. However in recent years, this paradigm has been slowly shifting towards the development and use of open-source data formats and tools, driven by upcoming observatories such as the Cherenkov Telescope Array (CTA). In this context, a community-driven, shared data format (the gamma-astro-data-format or GADF) and analysis tools such as Gammapy and ctools have been developed. So far these efforts have been led by the Imaging Atmospheric Cherenkov Telescope (IACT) community, leaving out other types of ground-based gamma-ray instruments.We aim to show that the data from ground particle arrays, such as the High-Altitude Water Cherenkov (HAWC) observatory, is also compatible with the GADF and can thus be fully analysed using the related tools, in this case Gammapy. We reproduce several published HAWC results using Gammapy and data products compliant with GADF standard. We also illustrate the capabilities of the shared format and tools by producing a joint fit of the Crab spectrum including data from six different gamma-ray experiments. We find excellent agreement with the reference results, a powerful check of both the published results and the tools involved. The data from particle detector arrays such as the HAWC observatory can be adapted to the GADF and thus analysed with Gammapy. A common data format and shared analysis tools allow multi-instrument joint analysis and effective data sharing. Given the complementary nature of pointing and wide-field instruments, this synergy will be distinctly beneficial for the joint scientific exploitation of future observatories such as the Southern Wide-field Gamma-ray Observatory and CTA.

Thousands of ring-like bubbles appear on infrared images of the Galaxy plane. Most of these infrared bubbles form during expansion of HII regions around massive stars. However, the physical effects that determine their morphology are still under debate. Namely, the absence of the infrared emission toward the centres of the bubbles can be explained by pushing the dust grains by stellar radiation pressure. At the same time, small graphite grains and PAHs are not strongly affected by the radiation pressure and must be removed by another process. Stellar ultraviolet emission can destroy the smallest PAHs but the photodestruction is ineffective for the large PAHs. Meanwhile, the stellar wind can evacuate all types of grains from HII regions. In the frame of our chemo-dynamical model we vary parameters of the stellar wind and illustrate their influence on the morphology and synthetic infrared images of the bubbles.

Fuzzy Dark Matter (FDM) models admit self-similar solutions which are very different from their Cold Dark Matter (CDM) counterparts and do not converge to the latter in the semiclassical limit. In contrast with the familiar CDM hierarchical collapse, they correspond to an inverse-hierarchy blow-up. Constant-mass shells start in the nonlinear regime, at early times, with small radii and high densities, and expand to reach at late times the Hubble flow, up to small linear perturbations. Thus, larger masses become linear first. This blow-up approximately follows the Hubble expansion, so that the central density contrast remains constant with time, although the width of the self-similar profile shrinks in comoving coordinates. As in a gravitational cooling process, matter is ejected from the central peaks through successive clumps. As in wave systems, the velocities of the geometrical structures and of the matter do not coincide, and matter slowly moves from one clump to the next, with intermittent velocity bursts at the transitions. These features are best observed using the density-velocity representation of the nonrelativistic scalar field, or the mass-shell trajectories, than with the Husimi phase-space distribution, where an analogue of the Heisenberg uncertainty principle blurs the resolution in the position or velocity direction. These behaviours are due to the quantum pressure and the wavelike properties of the Schr\"odinger equation. Although the latter has been used as an alternative to N-body simulations for CDM, these self-similar solutions show that the semiclassical limit needs to be handled with care.

Estimating stellar masses and radii is a challenge for most of the stars but their knowledge is critical for many different astrophysical fields. One of the most extended techniques for estimating these variables are the so-called empirical relations. In this work we propose a group of state-of-the-art AI regression models, with the aim of studying their proficiency in estimating stellar masses and radii. We publicly release the database, the AI models, and an online tool for stellar mass and radius estimation to the community. We use a sample of 726 MS stars in the literature with accurate M, R, T_eff, L, log g, and [Fe/H]. We have split our data sample into training and testing sets and then analyzed the different AI techniques with them. In particular, we have experimentally evaluated the accuracy of the following models: Linear Reg., Bayesian Reg., Regression Trees, Random Forest, Support-Vector Reg. (SVR), Neural Networks, kNN, and Stacking. We propose a series of experiments designed to evaluate the accuracy of the estimations. We have also analyzed the impact of reducing the number of inputs parameters and compared our results with those from state-of-the-art empirical relations in the literature. We have found that a Stacking of several regression models is the most suitable technique for estimating masses and radii. In the case of the mass, Neural Networks also provide precise results, and for the radius, SVR and Neural Networks work too. When comparing with other state-of-the-art empirical relations based models, our Stacking improves the accuracy by a factor of two for both variables. In addition, bias is reduced to one order of magnitude in the case of the stellar mass. Finally, we have found that using our Stacking and only T_eff and L as input features, the accuracies obtained are slightly larger than a 5%, with a bias approx 1.5%.

Searches for dark matter (DM) have not provided any solid evidence for the existence of weakly interacting massive particles in the GeV-TeV mass range. Coincidentally, the scale of new physics is being pushed by collider searches well beyond the TeV domain. This situation strongly motivates the exploration of DM masses much larger than a TeV. Secluded scenarios contain a natural way around the unitarity bound on the DM mass, via the early matter domination induced by the mediator of its interactions with the Standard Model. High-energy neutrinos constitute one of the very few direct accesses to energy scales above a few TeV. An indirect search for secluded DM signals has been performed with the ANTARES neutrino telescope using data from 2007 to 2015. Upper limits on the DM annihilation cross section for DM masses up to 6 PeV are presented and discussed.

Self-interacting dark matter (SIDM) models have received great attention over the past decade as solutions to the small-scale puzzles of astrophysics. Though there are different implementations of dark matter (DM) self-interactions in N-body codes of structure formation, there has not been a systematic study to compare the predictions of these different implementations. We investigate the implementation of dark matter self-interactions in two simulation codes: Gizmo and Arepo. We begin with identical initial conditions for an isolated $10^{10}$ M$_\odot$ dark matter halo and investigate the evolution of the density and velocity dispersion profiles in Gizmo and Arepo for SIDM cross-section over mass of 1, 5, and 50 $\rm cm^2 g^{-1}$. Our tests are restricted to the core expansion phase where the core density decreases and core radius increases with time. We find better than 30% agreement between the codes for the density profile in this phase of evolution, with the agreement improving at higher resolution. We find that varying code-specific SIDM parameters changes the central halo density by less than 10% outside of the convergence radius. We argue that SIDM core formation is robust across the two different schemes and conclude that these codes can reliably differentiate between cross-sections of 1, 5, and 50 $\rm cm^2 g^{-1}$ but finer distinctions would require further investigation.

We present redshift-zero synthetic dust-aware observations for the 45 Milky Way-mass simulated galaxies of the ARTEMIS project, calculated with the SKIRT radiative transfer code. The post-processing procedure includes components for star-forming regions, stellar sources, and diffuse dust. We produce and publicly release realistic high-resolution images for 50 commonly-used broadband filters from ultraviolet to sub-millimetre wavelengths and for 18 different viewing angles. We compare the simulated ARTEMIS galaxies to observed galaxies in the DustPedia database with similar stellar mass and star formation rate, and to synthetic observations of the simulated galaxies of the Auriga project produced in previous work using a similar post-processing technique. In all cases, global galaxy properties are derived using SED fitting. We find that, similar to Auriga, the post-processed ARTEMIS galaxies generally reproduce the observed scaling relations for global fluxes and physical properties, although dust extinction at FUV/UV wavelengths is underestimated and representative dust temperatures are lower than observed. At a resolved scale, we compare multi-wavelength non-parametric morphological properties of selected disc galaxies across the data sets. We find that the ARTEMIS galaxies largely reproduce the observed morphological trends as a function of wavelength, although they appear to be more clumpy and less symmetrical than observed. We note that the ARTEMIS and Auriga galaxies occupy adjacent regions in the specific star formation versus stellar mass plane, so that the synthetic observation data sets supplement each other.

The formation pathways for gravitational-wave merger sources are predicted to include common envelope (CE) evolution. Observations of high-mass post-common envelope binaries suggest that energy transfer to the envelope during the CE phase must be highly efficient. In contrast, observations of low-mass post-CE binaries indicate energy transfer during the CE phase must be highly inefficient. Convection, a process present in low-mass and high-mass stars, naturally explains this dichotomy. Using observations of Wolf-Rayet binaries, we study the effects of convection and radiative losses on the predicted final separations of high-mass common envelopes. Despite robust convection in massive stars, the effect is minimal as the orbit decays well before convection can transport the liberated orbital energy to the surface. In low-mass systems, convective transport occurs faster then the orbit decays, allowing the system to radiatively cool thereby lowering the efficiency. The inclusion of convection reproduces observations of low-mass and high-mass binaries and remains a necessary ingredient for determining outcomes of common envelopes.

GJ436b might be the prototype of warm Neptunes that have undergone late migration induced by an outer companion. Precise determination of the orbital architecture of such systems is critical to constraining their dynamical history and evaluating the role of delayed migration in the exoplanet population. To this purpose we analyzed the Rossiter-McLaughlin (RM) signal of GJ436 b in two transits - recently observed with ESPRESSO - using three different techniques. The high level of precision achieved in radial velocity (RV) measurements allows us to detect the deviation from the Keplerian orbit, despite the slow rotation of the M dwarf host (vsini = 272.0+40.0-34.0 m/s), and to measure the sky-projected obliquity ($\lambda$ = 102.5+17.2-18.5$^{\circ}$). The Reloaded RM technique, which allows the stellar RV field along the transit chord to be analyzed, yields $\lambda$ = 107.5+23.6-19.3$^{\circ}$ and vsini = 292.9+41.9-49.9 m/s. The RM Revolutions technique, which allows us to fit the spectral profiles from all planet-occulted regions together, yields $\lambda$ = 114.1+22.8-17.8$^{\circ}$ and vsini = 300.5+45.9-57.0 m/s. The consistent results between these three techniques, and with published results from HARPS/HARPS-N data, confirm the polar orbit of GJ436b and support the hypothesis that its origin lies in Kozai migration. Results from a joint RM Revolutions analysis of the ESPRESSO, HARPS, and HARPS-N datasets ($\lambda$ = 113.5+23.3-17.3$^{\circ}$; vsini = 293.5+43.7-52.2 m/s) combined with a revised stellar inclination ($i_\star$ = 35.7+5.9-7.6$^{\circ}$ or 144.2+7.6-5.9$^{\circ}$) lead us to constrain the 3D obliquity $\Psi$ to 103.2+12.8-11.5$^{\circ}$.

Studying the impact of systematic effects, optimizing survey strategies, assessing tensions between different probes and exploring synergies of different data sets require a large number of simulated likelihood analyses, each of which cost thousands of CPU hours. In this paper, we present a method to accelerate cosmological inference using emulators based on Gaussian process regression and neural networks. We iteratively acquire training samples in regions of high posterior probability which enables accurate emulation of data vectors even in high dimensional parameter spaces. We showcase the performance of our emulator with a simulated 3x2 point analysis of LSST-Y1 with realistic theoretical and systematics modelling. We show that our emulator leads to high-fidelity posterior contours, with an order of magnitude speed-up. Most importantly, the trained emulator can be re-used for extremely fast impact and optimization studies. We demonstrate this feature by studying baryonic physics effects in LSST-Y1 3x2 point analyses where each one of our MCMC runs takes approximately 5 minutes. This technique enables future cosmological analyses to map out the science return as a function of analysis choices and survey strategy.

In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant $H_0$, the $\sigma_8$--$S_8$ tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the $5.0\,\sigma$ tension between the {\it Planck} CMB estimate of the Hubble constant $H_0$ and the SH0ES collaboration measurements. After showing the $H_0$ evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the {\it Planck} CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density $\Omega_m$, and the amplitude or rate of the growth of structure ($\sigma_8,f\sigma_8$). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the $H_0$--$S_8$ tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals.[Abridged]

We present the observed HI size-mass relation of $204$ galaxies from the MIGHTEE Survey Early Science data. The high sensitivity of MeerKAT allows us to detect galaxies spanning more than 4 orders of magnitude in HI mass, ranging from dwarf galaxies to massive spirals, and including all morphological types. This is the first time the relation has been explored on a blind homogeneous data set which extends over a previously unexplored redshift range of $0 < z < 0.084$, i.e. a period of around one billion years in cosmic time. The sample follows the same tight logarithmic relation derived from previous work, between the diameter ($D_{\rm HI}$) and the mass ($M_{\rm HI}$) of HI discs. We measure a slope of $0.501\pm 0.008$, an intercept of $-3.252^{+0.073}_{-0.074}$, and an observed scatter of $0.057$ dex. For the first time, we quantify the intrinsic scatter of $0.054 \pm 0.003$ dex (${\sim} 10 \%$), which provides a constraint for cosmological simulations of galaxy formation and evolution. We derive the relation as a function of galaxy type and find that their intrinsic scatters and slopes are consistent within the errors. We also calculate the $D_{\rm HI} - M_{\rm HI}$ relation for two redshift bins and do not find any evidence for evolution with redshift. These results suggest that over a period of one billion years in lookback time, galaxy discs have not undergone significant evolution in their gas distribution and mean surface mass density, indicating a lack of dependence on both morphological type and redshift.

We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/\hri\ in 174 \AA. These dots are roundish, have a diameter of 675$\pm$300 km, a lifetime of 50$\pm$35 seconds, and an intensity enhancement of 30\% $\pm$10\% above their immediate surroundings. About half of the dots remain isolated during their evolution and move randomly and slowly ($<$10 \kms). The other half show extensions, appearing as a small loop or surge/jet, with intensity propagations below 30\,\kms. Many of the bigger and brighter \hri\ dots are discernible in SDO/AIA 171 \AA\ channel, have significant emissivity in the temperature range of 1--2 MK, and are often located at polarity inversion lines observed in HMI LOS magnetograms. Although not as pervasive as in observations, Bifrost MHD simulation of an emerging flux region do show dots in synthetic \fe\ images. These dots in simulation show distinct Doppler signatures -- blueshifts and redshifts coexist, or a redshift of the order of 10 \kms\ is followed by a blueshift of similar or higher magnitude. The synthetic images of \oxy\ and \siiv\ lines, which represent transition region radiation, also show the dots that are observed in \fe\ images, often expanded in size, or extended as a loop, and always with stronger Doppler velocities (up to 100 \kms) than that in \fe\ lines. Our observation and simulation results, together with the field geometry of dots in the simulation, suggest that most dots in emerging flux regions form in the lower solar atmosphere (at $\approx$1 Mm) by magnetic reconnection between emerging and pre-existing/emerged magnetic field. Some dots might be manifestations of magneto-acoustic shocks through the line formation region of \fe\ emission.

Long-period variable stars (LPVs) are pulsating red giants, primarily in the asymptotic giant branch phase, and they include both Miras and semi-regular variables (SRVs). Their period-age and period-luminosity relations enable us to trace different stellar populations, as they are intrinsically very bright and cover a wide range in distances and ages. The purpose of this study is to establish a census of LPV stars in a region close to the Galactic center, using the six-year database of the Vista Variables in the V\'ia L\'actea (VVV) ESO Public Survey, as well as to describe the methodology that was employed to search for and characterize LPVs using VVV data. Near-IR surveys such as VVV provide a unique opportunity to probe the high-extinction innermost regions of the Milky Way. The detection and analysis of the intrinsically bright Miras in this region could provide us with an excellent probe of the properties of the Milky Way far behind its bulge. We used point-spread function photometry for all available $K_{s}$-band images in ten VVV tiles, covering $16.4~\deg^2$ in total, overlapping fields observed in the course of the Optical Gravitational Lensing Experiment (OGLE)-III survey. We designed a method to select LPV candidates, and we used the known variables from OGLE-III and other known variables from the literature to test our approach. The reduced $\chi^2$ statistic, along with the flux-independent index $K_{(fi)}$, were used in our analysis. The Lomb-Scargle period search method, Fourier analysis, template fitting, and visual inspection were then performed to refine our sample and characterize the properties of the stars included in our catalog. A final sample of 130 Mira candidates, of which 129 are new discoveries, was thus obtained, with periods in the range between about 80 and 1400~days.

Integral field spectroscopy (IFS) provides a unique capability to spectroscopically study extended sources over a 2D field of view, but it also requires new techniques and tools. In this paper, we present an automatic code, Spectroscopic Analysis Tool for intEgraL fieLd unIt daTacubEs, SATELLITE, designed to fully explore such capability in the characterization of extended objects, such as planetary nebulae, H II regions, galaxies, etc. SATELLITE carries out 1D and 2D spectroscopic analysis through a number of pseudo-slits that simulate slit spectrometry, as well as emission line imaging. The 1D analysis permits direct comparison of the integral field unit (IFU) data with previous studies based on long-slit spectroscopy, while the 2D analysis allows the exploration of physical properties in both spatial directions. Interstellar extinction, electron temperatures and densities, ionic abundances from collisionally excited lines, total elemental abundances and ionization correction factors are computed employing the Pyneb package. A Monte Carlo approach is implemented in the code to compute the uncertainties for all the physical parameters. SATELLITE provides a powerful tool to extract physical information from IFS observations in an automatic and user configurable way. The capabilities and performance of SATELLITE are demonstrated by means of a comparison between the results obtained from the Multi Unit Spectroscopic Explorer (MUSE) data of the planetary nebula NGC 7009 with the results obtained from long-slit and IFU data available in the literature. The SATELLITE characterization of NGC 6778 based on MUSE data is also presented.

The physical scale corresponding to baryon acoustic oscillations (BAO), the size of the sound horizon at recombination, is precisely determined by CMB experiments. Measuring the apparent size of the BAO scale imprinted in the clustering of galaxies gives us a direct estimate of the angular-diameter distance and the Hubble parameter as a function of redshift. The BAO feature is damped by non-linear structure formation, which reduces the precision with which we can infer the BAO scale from standard galaxy clustering analysis methods. Many methods to undo this damping via the so-called BAO reconstruction have so far been proposed; however, they all rely on backward modeling. In this paper, we present the first results of BAO inference from rest-frame halo catalogs using forward modeling combined with the EFT likelihood, in the case where the initial phases of the density field are fixed. We show that the remaining systematic bias is less than 2% when we consider cutoff values of $\Lambda \leq 0.25 \,h\,{\rm Mpc}^{-1}$ for all halo samples considered, and below 1% and consistent with zero for all but the most highly biased samples. We also demonstrate that, when compared to the standard power spectrum likelihood approach under the same assumption of fixed phases, the 1$\sigma$ errors associated to the field level inference of the BAO scale are 1.1 to 3.3 times smaller, depending on the value of the cutoff and the halo sample. Our analysis therefore unveils another promising feature of using field-level inference for high-precision cosmology

Spontaneous scalarization of neutron stars has been extensively studied in the Damour and Esposito-Far\`ese model, in which a scalar field couples to the Ricci scalar or, equivalently, to the trace of the energy-momentum tensor. However, scalarization of both black holes and neutron stars may also be triggered by a coupling of the scalar field to the Gauss-Bonnet invariant. The case of the Gauss-Bonnet coupling has also received a lot of attention lately, but the synergy of the Ricci and Gauss-Bonnet couplings has been overlooked for neutron stars. Here, we show that combining both couplings has interesting effects on the properties of scalarized neutron stars, such as affecting their domain of existence or the amount of scalar charge they carry.

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

We study a model of quintessential inflation constructed in $R^2$ modified gravity with a non-minimally coupled scalar field, in the Palatini formalism. Our non-minimal inflaton field is characterised by a simple exponential potential. We find that successful quintessential inflation can be achieved with no fine-tuning on the model parameters. Predictions on the characteristics of dark energy will be tested by observations in the near future, while contrast with existing observations provides insights on the modified gravity background, such as the value of the non-minimal coupling and its running.

A popular proposal for resolving the Hubble tension involves an early phase of dark energy, driven by an axion field with a periodic potential. In this paper, we argue that these models are tightly constrained by the axion weak gravity conjecture: for typical parameter values, the axion decay constant must satisfy $f < 0.008 M_{\textrm{Pl}}$, which is smaller than the axion decay constants appearing in the vast majority of early dark energy models to date. We discuss possible ways to evade or loosen this constraint, arguing that its loopholes are small and difficult to thread. This suggests that it may prove challenging to realize early dark energy models in a UV complete theory of quantum gravity.

Tau neutrinos are the least studied particle in the Standard Model. This whitepaper discusses the current and expected upcoming status of tau neutrino physics with attention to the broad experimental and theoretical landscape spanning long-baseline, beam-dump, collider, and astrophysical experiments. This whitepaper was prepared as a part of the NuTau2021 Workshop.

In this work we characterize the expected gravitational wave signal detectable by the planned space-borne interferometer LISA and the proposed next generation space-borne interferometer $\mu$Ares arising from a population of primordial black holes orbiting Sgr A*, the super-massive black hole at the Galactic center. Assuming that such objects indeed form the entire diffuse mass allowed by the observed orbit of S2 in the Galactic center, under the simplified assumption of circular orbits and monochromatic mass function, we assess the expected signal in gravitational waves, either from resolved and non-resolved sources.

In this paper, as a supplementary of our study on the angular distribution of the recoil flux of WIMP-scattered target nuclei and on that of the WIMP effective scattering velocity distribution, we investigate the scattering probability distribution of the WIMP incident velocity versus the nuclear recoil angle in narrow recoil energy windows for different WIMP masses and target nuclei. Our simulation results show that, not only the velocity distribution of incident halo WIMPs, but also a factor of the recoil angle could affect the scattering probability distribution of the available incident velocity-recoil angle combination in a given recoil energy window. Consequently, the 1-D WIMP "effective" velocity distribution corresponding to the considered narrow energy window would not be consistent with that cut simply from the (generating) velocity distribution of incident halo WIMPs. And its contribution to the differential WIMP-nucleus scattering event rate in the considered energy window could thus not be simply estimated by integrating over the 1-D theoretical velocity distribution (of entire halo WIMPs).

Taiji-1 is the first technology demonstration satellite of the Taiji program of China's space-borne gravitational wave antenna. After the demonstration of the key individual technologies, Taiji-1 continues collecting the data of the precision orbit determinations, the satellite attitudes, and the non-conservative forces exerted on the S/C. Therefore, during its free-fall, Taiji-1 can be viewed as operating in the high-low satellite-to-satellite tracking mode of a gravity recovery mission. In this work, one month data from Taiji-1's observations have been selected and the techniques are developed to resolve the long term interruptions and disturbances in the measurement data due to the scheduled technology demonstration experiments. The first global gravity model TJGM-r1911, that independently derived from China's own satellite mission, is successfully built from Taiji-1's observations. Compared with gravity models from CHAMP and other satellite gravity missions, accuracy discrepancies exist, which is mainly caused by the data discontinuity problem. As the approved extended free-falling phase with minimal disruptions and disturbances, Taiji-1 will serve as the first satellite gravity mission for China since 2022 and will provide us the independent measurement of both the static and the monthly time-variable global gravity field.

Recoil imaging entails the detection of spatially resolved ionization tracks generated by particle interactions. This is a highly sought-after capability in many classes of detector, with broad applications across particle and astroparticle physics. However, at low energies, where ionization signatures are small in size, recoil imaging only seems to be a practical goal for micro-pattern gas detectors. This white paper outlines the physics case for recoil imaging, and puts forward a decadal plan to advance towards the directional detection of low-energy recoils with sensitivity and resolution close to fundamental performance limits. The science case covered includes: the discovery of dark matter into the neutrino fog, directional detection of sub-MeV solar neutrinos, the precision study of coherent-elastic neutrino-nucleus scattering, the detection of solar axions, the measurement of the Migdal effect, X-ray polarimetry, and several other applied physics goals. We also outline the R\&D programs necessary to test concepts that are crucial to advance detector performance towards their fundamental limit: single primary electron sensitivity with full 3D spatial resolution at the $\sim$100 micron-scale. These advancements include: the use of negative ion drift, electron counting with high-definition electronic readout, time projection chambers with optical readout, and the possibility for nuclear recoil tracking in high-density gases such as argon. We also discuss the readout and electronics systems needed to scale-up such detectors to the ton-scale and beyond.

Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy as it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and other space-based instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA's first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed: ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or intermediate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help make progress in the different areas. New research avenues that LISA itself, or its joint exploitation with studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe.

In this talk, we discuss the physics modeling of antiproton spectra arising from dark matter (DM) annihilation or decay in a model-independent manner. The modeling of antiproton spectra contains some intrinsic uncertainties related to QCD parton showers and hadronisation of baryons. We briefly assess the sources of these uncertainties and their impact on antiproton energy spectra for a few selected DM scenarios. The results are provided in tabulated form for future analyses.

Understanding the electronic transport properties of iron under high temperatures and pressures is essential for constraining geophysical processes. The difficulty of reliably measuring these properties under Earth-core conditions calls for sophisticated theoretical methods that can support diagnostics. We present results of the electrical conductivity within the pressure and temperature ranges found in Earth's core from simulating microscopic Ohm's law using time-dependent density functional theory. Our predictions provide a new perspective on resolving discrepancies in recent experiments.

We address the issue of black hole scalarization and its compatibility with cosmic inflation and big bang cosmology from an effective field theory (EFT) point of view. In practice, using a well-defined and healthy toy model which (in part) has been broadly considered in the literature, we consider how higher-order theories of gravity, up to cubic operators in Riemann curvature, fit within this context. Interestingly enough, we find that already at this minimal level, there is a non-trivial interplay between the Wilson coefficients which are otherwise completely independent, constraining the parameter space where scalarization may actually occur. Conclusively, we claim that the EFT does exhibit black hole scalarization, remaining compatible with the inflationary paradigm, and admitting General Relativity as a cosmological attractor.

Next-generation dark matter (DM) detectors searching for weakly interacting massive particles (WIMPs) will be sensitive to coherent scattering from solar neutrinos, demanding an efficient background-signal discrimination tool. Directional detectors improve sensitivity to WIMP DM despite the irreducible neutrino background. Wide-bandgap semiconductors offer a path to directional detection in a high-density target material. A detector of this type operates in a hybrid mode. The WIMP or neutrino-induced nuclear recoil is detected using real-time charge, phonon, or photon collection. The directional signal, however, is imprinted as a durable sub-micron damage track in the lattice structure. This directional signal can be read out by a variety of atomic physics techniques, from point defect quantum sensing to x-ray microscopy. In this white paper, we present the detector principle and review the status of the experimental techniques required for directional readout of nuclear recoil tracks. Specifically, we focus on diamond as a target material; it is both a leading platform for emerging quantum technologies and a promising component of next-generation semiconductor electronics. Based on the development and demonstration of directional readout in diamond over the next decade, a future WIMP detector will leverage or motivate advances in multiple disciplines towards precision dark matter and neutrino physics.

A 1494 Dalton hemoglycin space polymer of Glycine18 Hydroxy-glycine4 Fe2O4 termed the core unit is part of a polymer of Glycine, Si, Fe and O that forms tubes, vesicles and a lattice structure isolated from CV3 meteorites and characterized by mass spectrometry, FIB/SIMS and X-ray analysis. In Hartree-Fock calculations the polymer has an absorption of blue light at 480nm that is dependent on rectus R (= dextro D) chirality in a hydroxy-glycine residue whose C-terminus is bonded to an iron atom. The absorption originates in the Fe II state as a consequence of chiral symmetry breaking. The infrared spectrum is presented. We discuss how the core unit could have been selected 4.5 billion years ago in our protoplanetary disc by blue light from the early sun.

Physical theories grounded in mathematical symmetries are an essential component of our understanding of a wide range of properties of the universe. Similarly, in the domain of machine learning, an awareness of symmetries such as rotation or permutation invariance has driven impressive performance breakthroughs in computer vision, natural language processing, and other important applications. In this report, we argue that both the physics community and the broader machine learning community have much to understand and potentially to gain from a deeper investment in research concerning symmetry group equivariant machine learning architectures. For some applications, the introduction of symmetries into the fundamental structural design can yield models that are more economical (i.e. contain fewer, but more expressive, learned parameters), interpretable (i.e. more explainable or directly mappable to physical quantities), and/or trainable (i.e. more efficient in both data and computational requirements). We discuss various figures of merit for evaluating these models as well as some potential benefits and limitations of these methods for a variety of physics applications. Research and investment into these approaches will lay the foundation for future architectures that are potentially more robust under new computational paradigms and will provide a richer description of the physical systems to which they are applied.

New particles coupled to the Standard Model can equilibrate in stellar cores if they are sufficiently heavy and strongly coupled. In this work, we investigate the astrophysical consequences of such a scenario for massive stars by incorporating new contributions to the equation of state into a state of the art stellar structure code. We focus on axions in the "cosmological triangle", a region of parameter space with $300{\rm\,keV} \lesssim m_a \lesssim 2$ MeV, $g_{a\gamma\gamma}\sim 10^{-5}$ GeV$^{-1}$ that is not presently excluded by other considerations. We find that for axion masses $m_a \sim m_e $, axion production in the core drives a new stellar instability that results in explosive nuclear burning that either drives a series of mass-shedding pulsations or completely disrupts the star resulting in a new type of optical transient -- an \textit{Axion Instability Supernova}. We predict that the upper black hole mass gap would be located at $37{\rm M}_\odot \le M\le 107{\rm M}_\odot$ in these theories, a large shift down from the standard prediction, which is disfavored by the detection of the mass gap in the LIGO/Virgo/KAGRA GWTC-2 gravitational wave catalog beginning at $46_{-6}^{+17}{\rm M}_\odot$. Furthermore, axion-instability supernovae are more common than pair-instability supernovae, making them excellent candidate targets for JWST. The methods presented in this work can be used to investigate the astrophysical consequences of any theory of new physics that contains heavy bosonic particles of arbitrary spin. We provide the tools to facilitate such studies.