Papers for Monday, Sep 25 2023

We assess the modification of angular momentum transport in various configurations of star-disk accreting systems based on numerical simulations with different parameters. We quantify the torques exerted on a star by the various components of the flow in our simulations of a star-disk magnetospheric interaction. We obtained results using different stellar rotation rates, dipole magnetic field strengths, and resistivities. We probed a part of the parameter space with slowly rotating central objects, up to 20% of the Keplerian rotation rate at the equator. Different components of the flow in star-disk magnetospheric interaction were considered in the study: a magnetospheric wind (i.e., the ``stellar wind'') ejected outwards from the stellar vicinity, matter infalling onto the star through the accretion column, and a magnetospheric ejection launched from the magnetosphere. We also took account of trends in the total torque in the system and in each component individually. We find that for all the stellar magnetic field strengths, B$_\star$, the anchoring radius of the stellar magnetic field in the disk is extended with increasing disk resistivity. The torque exerted on the star is independent of the stellar rotation rate, $\Omega_\star$, in all the cases without magnetospheric ejections. In cases where such ejections are present, there is a weak dependence of the anchoring radius on the stellar rotation rate, with both the total torque in the system and torque on the star from the ejection and infall from the disk onto the star proportional to $\Omega_\star B^3$. The torque from a magnetospheric ejection is proportional to $\Omega_\star^4$. Without the magnetospheric ejection, the spin-up of the star switches to spin-down in cases involving a larger stellar field and faster stellar rotation. The critical value for this switch is about 10% of the Keplerian rotation rate.

A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of their atmosphere and infer their formation processes and evolution. Such a goal represents a major challenge owing to their small angular separation and luminosity contrast with respect to their parent stars. Instead of designing and implementing completely new facilities, it has been proposed to leverage the capabilities of existing instruments that offer either high contrast imaging or high dispersion spectroscopy, by coupling them using optical fibers. In this work we present the implementation and first on-sky results of the HiRISE instrument at the very large telescope (VLT), which combines the exoplanet imager SPHERE with the recently upgraded high resolution spectrograph CRIRES using single-mode fibers. The goal of HiRISE is to enable the characterization of known companions in the $H$ band, at a spectral resolution of the order of $R = \lambda/\Delta\lambda = 100\,000$, in a few hours of observing time. We present the main design choices and the technical implementation of the system, which is constituted of three major parts: the fiber injection module inside of SPHERE, the fiber bundle around the telescope, and the fiber extraction module at the entrance of CRIRES. We also detail the specific calibrations required for HiRISE and the operations of the instrument for science observations. Finally, we detail the performance of the system in terms of astrometry, temporal stability, optical aberrations, and transmission, for which we report a peak value of $\sim$3.9% based on sky measurements in median observing conditions. Finally, we report on the first astrophysical detection of HiRISE to illustrate its potential.

We present the analysis of the full MaNGA DR17 sample to characterize its population of compact galaxies. We focus on galaxies that fill the stellar mass (M$_{\star}$) gap between compact elliptical galaxies (cEs; $8 \lesssim \log \left(M_{\star} / M_{\odot} \right) \lesssim 10$) and compact massive galaxies (CMGs; $10 \lesssim \log \left(M_{\star} / M_{\odot} \right)$). We study their stellar populations and kinematics to reveal how their properties depend on stellar mass. We select compact galaxies in the MaNGA DR17 sample according to their effective radius ($R_e$) and stellar mass. 37 galaxies fulfill our selection criteria in the bridging region between cEs and CMGs. We derive their kinematics and stellar population parameters from the stacked spectra at 1~$R_e$ using a full spectral fitting routine. We then classify the selected compact galaxies in three main groups based on their stellar population properties. One of the groups shows characteristics compatible with relic galaxies, i.e. galaxies that have remained mostly unchanged since their early formation epoch ($z \sim 2$). Another group shows more extended and continuous star formation histories (SFHs). The third group shows a low star-forming rate at initial times, which increases at around $\sim4$ Gyr. We compare the derived properties of the selected galaxies with those of previously studied compact galaxies at different mass ranges. The selected galaxies successfully fill the mass gap between cEs and CMGs. Their properties are compatible with the assumption that the scaling relations of compact galaxies at different mass ranges are related, although galaxies in the first group are clear outliers in the fundamental plane, suggesting different formation mechanisms for this relic population.

Using the final MaNGA sample (DR17) of 10K galaxies, we investigate the dark matter fraction $f_{\rm DM}$ within one half-light radius $R_{\rm e}$ for about 6K galaxies with good kinematics spanning a wide range of morphologies and stellar velocity dispersion ($1.6\lesssim \lg\,\sigma_{\rm e}/\mathrm{km\,s^{-1}}\lesssim 2.6$). We employ two techniques to estimate $f_{\rm DM}$: (i) Jeans Anisotropic Modelling (JAM), which performs dark matter decomposition based on the stellar kinematics and (ii) comparing the total dynamical mass-to-light ratios $(M/L)_{\rm JAM}$ and the $(M_{\ast}/L)_{\rm SPS}$ from Stellar Population Synthesis (SPS). We find that both methods consistently show a significant trend of increasing $f_{\rm DM}$ with decreasing $\sigma_{\rm e}$, for $\lg(\sigma_{\rm e}/\mathrm{km\,s^{-1}})\lesssim2.1$ and very low $f_{\rm DM}$ at larger $\sigma_{\rm e}$. For the 235 early-type galaxies with the best dynamical models, we explore the variation of the stellar initial mass function (IMF) by comparing the stellar mass-to-light ratios $(M_{\ast}/L)_{\rm JAM}$ from JAM and SPS. We confirm that the stellar mass excess $\alpha_{\rm IMF}\equiv (M_{\ast}/L)_{\rm JAM}/(M_{\ast}/L)_{\rm SPS}$, which reflects the IMF shape, increases with $\sigma_{\rm e}$, in agreement with previous studies that reported a transition from Chabrier-like to Salpeter IMF among galaxies. We also detect weak positive correlations between $\alpha_{\rm IMF}$ and age, but no correlations with metallicity ($[Z/H]$). Finally, we stack galaxy spectra according to their $\alpha_{\rm IMF}$ to search for differences in IMF-sensitive spectral features (e.g. the $\rm Na_{\rm I}$ doublet). We only find marginal evidence for such differences, which casts doubt on the validity of one or both methods to measure the IMF.

We investigate K2BS5, an optical transient that we identified in Campaign 13 of the Kepler/K2 archives by the "K2 Background Survey", and classify it as a new SU UMa-type dwarf nova. Using the light curve generated from Kepler's long-cadence observation mode, we analyze the dwarf nova during quiescence and superoutburst. Following 20 days of quiescence at the start of the observation, the system entered a superoutburst lasting 12 days, after which it experienced at least one rebrightening. K2BS5 clearly meets the criteria for an SU UMa star, but at the peak of the superoutburst, it also shows double-wave oscillations consistent with the spectroscopic orbital period, a phenomenon that closely resembles early superhumps in WZ Sge stars. While we do not classify K2BS5 as a WZ Sge system, we discuss how this phenomenon could complicate efforts to use the suspected detection of early superhumps to distinguish SU UMa-type dwarf novae from the recently recognized class of long-orbital-period WZ Sge systems.

We present a method to obtain a high-significance detection of relativistic effects on cosmological scales. Measurements of such effects would be instrumental for our understanding of the Universe, as they would provide a further confirmation of the validity of general relativity as the correct description of the gravitational interaction, in a regime very far from that of strong gravity, where it has been tested to exquisite accuracy. Despite its relevance, detection of relativistic effects have hitherto eluded us, mainly because they are stronger on the largest cosmic scales, plagued by cosmic variance. Our work focusses on the cosmological probe of galaxy clustering, describing the excess probability of finding pairs of galaxies at a given separation due to them being part of the same underlying cosmic large-scale structure. In particular, we focus on the two-point correlation function of the distribution of galaxies in Fourier space$-$the power spectrum$-$where relativistic effects appear as an imaginary contribution to the real power spectrum. By carefully tailoring cuts in magnitude/luminosity, we are able to obtain two samples (bright and faint) of the same galaxy population, whose cross-correlation power spectrum allows for a detection of the relativistic contribution well above a significance of $5\,\sigma$.

For low-mass haloes, the physical origins of halo assembly bias have been linked to the slowdown of accretion due to tidal forces, which are expected to be more dominant in some cosmic-web environments as compared to others. In this work, we use publicly available data from the application of the Discrete Persistent Structures Extractor (DisPerSE) to the IllustrisTNG magnetohydrodynamical simulation to investigate the dependence of the related galaxy assembly bias effect on the cosmic web. We first show that, at fixed halo mass, the galaxy population displays significant low-mass secondary bias when split by distance to DisPerSE critical points representing nodes ($d_{\rm node}$), filaments ($d_{\rm skel}$), and saddles ($d_{\rm sadd}$), with objects closer to these features being more tightly clustered. The secondary bias produced by some of these parameters exceeds the assembly bias signal considerably at some mass ranges, particularly for $d_{\rm sadd}$. We also demonstrate that the assembly bias signal is reduced significantly when clustering is conditioned to galaxies being close or far from these critical points. The maximum attenuation is measured for galaxies close to saddle points, where less than 35$\%$ of the signal remains. Conversely, objects near voids preserve a fairly pristine effect (almost 85$\%$ of the signal). Our analysis confirms the important role played by the tidal field in shaping assembly bias, but they are also consistent with the signal being the result of different physical mechanisms. Our work introduces some new aspects of secondary bias where the predictions from hydrodynamical simulations can be directly tested with observational data.

Gamma-ray observations of the Galactic Center (GC) region provide some of the most sensitive measurements of annihilation signals from dark matter in the GeV-TeV mass range. We present the first results from 178 hours of VERITAS observations of a 2 degree region around the GC, taken between 2010 and 2022. The analysis uses a newly-developed template-based background method, as well as analysis techniques optimized for observations taken at large zenith angles. No significant excess is found in any region of interest considered. We derive model-independent limits on the dark matter thermally-averaged annihilation cross section which are among the strongest from any indirect detection experiment for TeV-scale masses.

We have studied a star-forming complex S193 using near-infrared (NIR) observations and other archival data covering optical to radio wavelengths. We identified stellar clusters in the complex using the NIR photometric data and estimated the membership and distance of the clusters. Using the mid-infrared (MIR) and far-infrared (FIR) images, the distribution of the dust emission around H\,{\sc ii} regions is traced in the complex. The $Herschel$ column density and temperature maps analysis reveal 16 cold dust clumps in the complex. The H$\alpha$ image and 1.4 GHz radio continuum emission map are employed to study the ionised gas distribution and infer the spectral type and the dynamical age of each H\,{\sc ii} region/ionised clump in the complex. The $^{12}$CO(J =3$-$2) and $^{13}$CO(J =1$-$0) molecular line data hint at the presence of two velocity components around [-43,-46] and [-47,-50] km/s, and their spatial distribution reveals two overlapping zones toward the complex. By investigating the immediate surroundings of the central cluster [BDS2003]57 and the pressure calculations, we suggest that the feedback from the massive stars seems responsible for the observed velocity gradient and might have triggered the formation of the central cluster [BDS2003]57.}

The NectarCAM is a camera that will be mounted on the Medium-Sized Telescopes of the Cherenkov Telescope Array (CTA) observatory. Along with the hardware integration of the camera, the scientific software, $\texttt{nectarchain}$, is being developed. The software is responsible for transforming the raw data from the camera into analysis-ready calibrated data. In this contribution, we present the structure of the software, which consists of two modules: the calibration pipeline and the data quality check pipeline. The calibration pipeline reduces the data, performs flat fielding, and determines the gain for the analysis. The data quality monitoring pipeline is used to select the data that meets the necessary standards for analysis. Additionally, we discuss the format of the downstream data and the integration of the $\texttt{nectarchain}$ modules in the general software framework of CTA. We also present the necessary tests for validating each part of the code. We conclude by mentioning the prospects for the future of the software.

The Astronomical Genealogy Project (AstroGen) has been underway since January 2013. This project of the Historical Astronomy Division (HAD) of the American Astronomical Society (AAS) has been online since July 2020, courtesy of the AAS. The volunteers of the AstroGen team have systematically searched online directories, mostly at individual university libraries, for astronomy-related doctoral theses equivalent to the modern, research-based Ph.D. We now claim to be 'nearly complete' for 38 countries, although some have not been updated for a year or two or three. The website contains a page for each astronomer and advisor, with links to the persons, universities, institutes, and the theses themselves. More than two-thirds of the theses are online in full, although some require access to a library with a subscription. There is information about nearly 37,000 individuals who have earned astronomy-related doctorates and another 5400 who have supervised them, but may not have earned such degrees themselves. Most of the latter have not yet been evaluated, but probably a majority earned doctorates in other fields, such as physics or geology. We present some of the results of our research and discuss ten ways the reader might make use of the project.

Context: High-resolution spectra in the near-infrared (NIR) are an important tool for the detailed study of stellar atmospheres. The accurate identification of elements and molecules in these spectra can be used to determine chemical abundances and physical conditions in the photosphere of the observed star. Such identifications require precise line positions and strengths of both atomic and molecular features. Aims: This work focusses on the full identification of absorption lines in the NIR spectrum of the K-giant 10 Leo, including previously unidentified lines. The large number and complexity of the observed absorption lines require a deep search for potential spectral signatures to enable an unambiguous assignment to specific elements or molecular species. We aim to improve the published line lists of metals, some of which are determined by model calculations only, and many of which presently lack the completeness and accuracy of line parameters. Methods: The CRIRES-POP project provided high-resolution, high signal-to-noise ratio (S/N) spectra of several bright stars in the 1 to 5 $\mu$m range. For the K-giant 10 Leo, a spectrum corrected for telluric absorption and with precise wavelength calibration is available. This has been analysed by comparison with model spectra and up-to-date line lists. Results: We identified lines of 29 elements and eight molecular species. While the positions of many known lines could be confirmed, about 6% of all lines detected in 10 Leo could not be attributed to any known feature. For CO and its isotopologues, molecular constants could be derived and several additional lines identified. We report major inconsistencies for some prominent lines. In addition, abundances for several key elements in 10 Leo are provided.

We explore the relationship between the thermal Sunyaev-Zel'dovich (tSZ) power spectrum amplitude and the halo mass and redshift of galaxy clusters in South Pole Telescope (SPT) data, in comparison with three $N$-body simulations combined with semi-analytical gas models of the intra-cluster medium. Specifically, we calculate both the raw and fractional power contribution to the full tSZ power spectrum amplitude at $\ell = 3000$ from clusters as a function of halo mass and redshift. We use nine mass bins in the range $1 \times 10^{14}\ M_\odot\ h^{-1} < M_{500} < 2 \times 10^{15}\ M_\odot\ h^{-1}$, and two redshift bins defined by $0.25 < z < 0.59$ and $0.59 < z < 1.5$. We additionally divide the raw power contribution in each mass bin by the number of clusters in that bin, as a metric for comparison of different gas models. At lower masses, the SPT data prefers a model that includes a mass-dependent bound gas fraction component and relatively high levels of AGN feedback, whereas at higher masses there is a preference for a model with a lower amount of feedback and a complete lack of non-thermal pressure support. The former provides the best fit to the data overall, in regards to all metrics for comparison. Still, discrepancies exist and the data notably exhibits a steep mass-dependence which all of the simulations fail to reproduce. This suggests the need for additional mass- and redshift-dependent adjustments to the gas models of each simulation, or the potential presence of contamination in the data at halo masses below the detection threshold of SPT-SZ. Furthermore, the data does not demonstrate significant redshift evolution in the per-cluster tSZ power spectrum contribution, in contrast to most model predictions.

We present the abundance gradients of the Large Magellanic Cloud (LMC) for 25 elemental abundance ratios and their respective temporal evolution as well as age-[X/Fe] trends using 6130 LMC field red giant branch (RGB) stars observed by SDSS-IV / APOGEE-2S. APOGEE is a high resolution ($R$ $\sim$22,500) $H$-band spectroscopic survey that gathered data on the LMC with broad radial and azimuthal coverage out to $\sim$10\degr. The calculated overall metallicity gradient of the LMC with no age binning is $-$0.0380 $\pm$ 0.0022 dex/kpc. We also find that many of the abundance gradients show a U-shaped trend as functions of age. This trend is marked by a flattening of the gradient but then a general steepening at more recent times. The extreme point at which all these gradients (with the U-shaped trend) begin to steepen is $\gtrsim$2 Gyr ago. In addition, some of the age-[X/Fe] trends show an increase starting a few Gyr before the extreme point in the gradient evolutions. A subset of the age-[X/Fe] trends also show maxima concurrent with the gradients' extreme points, further pinpointing a major event in the history of the LMC $\sim$2 Gyr ago. This time frame is consistent with a previously proposed interaction between the Magellanic Clouds suggesting that this is most likely the cause of the distinct trend in the gradients and age-[X/Fe] trends.

The possible connection between high energy neutrinos in the energy region above 100 TeV and ultrahigh energy cosmic rays (UHECRs) at energies above $10^{19}$ eV motivates multi-messenger observation approaches involving neutrinos and the multi-wavelength electro-magnetic (EMG) signals. We have constructed a generic unification scheme to model the neutrino and UHECR common sources. Finding the allowed space of the parameters on the source characteristics allows a case study to evaluate the likelihood of each of the known source classes being such unified sources. The likely source candidates are transient or flaring objects mainly in optical and X-ray bands. We propose the two feasible strategies to identify these sources. One is to introduce a sub-threshold triggering in a wide field of view X-ray observatory for following up neutrino detections, and the other is to search for EMG counterparts associated with detections of multiple neutrino events coming from the same direction within a time scale of $\lesssim 30$ days. Sources with a total neutrino emission energy greater than $\sim 10^{51}$ erg are accessible with the present or near-future high energy neutrino observation facilities collaborating with X-rays and optical telescopes currently in operation. The neutrino-driven multi-messenger observations provide a smoking gun to probe the hadronic emission sources we would not be able to find otherwise.

Galaxy cluster mergers are rich sources of information to test cluster astrophysics and cosmology. However, cluster mergers produce complex projected signals that are difficult to interpret physically from individual observational probes. Multi-probe constraints on both the baryonic and dark matter cluster components are necessary to infer merger parameters that are otherwise degenerate. We present ICM-SHOX (Improved Constraints on Mergers with SZ, Hydrodynamical simulations, Optical, and X-ray), a systematic framework to jointly infer multiple merger parameters quantitatively via a pipeline that directly compares a novel combination of multi-probe observables to mock observables derived from hydrodynamical simulations. We report on a first application of the ICM-SHOX pipeline to the MACS J0018.5+1626 system, wherein we systematically examine simulated snapshots characterized by a wide range of initial parameters to constrain the MACS J0018.5+1626 merger parameters. We strongly constrain the observed epoch of MACS J0018.5+1626 to within $\approx -10$--$50$ Myr of the pericenter passage, and the observed viewing angle is inclined $\approx 25$--$38$ degrees from the merger axis. We obtain less precise constraints for the impact parameter ($\approx 100$--250 kpc), the mass ratio ($\approx 1.5$--$3.0$), and the initial relative velocity when the cluster components are separated by 3 Mpc ($\approx 1700$--3000 km s$^{-1}$). The primary and secondary cluster components initially (at 3 Mpc) have gas distributions that are moderately and strongly disturbed, respectively. We further discover a velocity space decoupling of the dark matter and baryonic distributions in MACS J0018.5+1626, which we attribute to the different collisional natures of the two distributions.

Recent experiments show that the desorption energy of H$_2$ on a diamond-like carbon (DLC) surface depends on the H$_2$ coverage of the surface. We aim to quantitatively explain the coverage dependent H$_2$ desorption energy measured by the experiments. We derive a math formula to calculate an effective H$_2$ desorption energy based on the encounter desorption mechanism. The effective H$_2$ desorption energy depends on two key parameters, the desorption energy of H$_2$ on H$_2$ substrate and the ratio of H$_2$ diffusion barrier to its desorption energy. The calculated effective H$_2$ desorption energy qualitatively agrees with the coverage dependent H$_2$ desorption energy measured by the experiments if the values of these two parameters in literature are used in the calculations. We argue that the difference between the effective H$_2$ desorption energy and the experimental results is due to the lacking of knowledge about these two parameters. So, we recalculate these two parameters based on experimental data. Good agreement between theoretical and experimental results can be achieved if these two updated parameters are used in the calculations.

In this paper, the evolution of exoplanet orbits at the late stages of stellar evolution is studied by the method of population synthesis. The evolution of stars is traced from the Main Sequence stage to the white dwarf stage. The MESA package is used to calculate evolutionary tracks. The statistics of absorbed, ejected, and surviving planets by the time of the transformation of parent stars into white dwarfs are calculated taking into account the change in the rate of star formation in the Galaxy over the entire time of its existence. Planets around stars in the range of initial masses 1-8 $M_\odot$ are considered since less massive stars do not have time to leave the Main Sequence during the lifetime of the Galaxy, and more massive ones do not lead to the formation of white dwarfs. It is shown that with the initial $a$~--~$M_\mathrm{pl}$ distribution of planets adopted in this work, most (about 60\%) of the planets born from stars in the mass range under study are absorbed by their parent stars at the giant stage. A small fraction of the planets (less than one percent) are ejected from their systems because of the mass loss due to the stellar wind. The estimated number of ejected planets with masses ranging from 0.04 Earth masses to 13 Jupiter masses in the Milky way is approximately equal to 300 million.

We present the results from the spectral and timing analysis of the accreting neutron star 1A~1744-361 from the \nustar{} observation performed in its 2022 outbursts. The unabsorbed bolometric X-ray luminosity during this observation in the energy band $0.1-100\kev{}$ is $3.9\times 10^{37}$ erg~s$^{-1}$, assuming a distance of $9$ kpc. During this observation, the source was in the banana branch of the atoll track. The source spectrum exhibits relativistic disc reflection and clear absorption features when an absorbed blackbody and cut-off power-law model describes the continuum emission. The $3-50\kev{}$ source spectrum is well fitted using a model combination consisting of an absorbed single-temperature blackbody and a reflection model along with the addition of a warm absorber component. The inner-disk radius, $R_{in}$, obtained from the reflection fit is $\sim(1.61-2.86)R_{ISCO}=(8.4-14.9)R_{g}$ ($17.6-31.2$ km for a $1.4\Msun$ NS). This measurement allowed us to further constrain the magnetic field strength to $B\lesssim 0.94\times 10^{9}$G. The strong absorption features $\sim 6.91\kev{}$ and $\sim 7.99\kev{}$ imply the presence of highly ionized absorbing material with a column density $N_{H}$ of $\sim 3\times 10^{22}$ cm$^{-2}$, emanating from the accretion disk in the form of disc wind with an outflow velocity of $v_{out}\simeq 0.021c\simeq 6300$ km s$^{-1}$.

Magnetic fields can be generated in cosmic string wakes due to the Biermann mechanism in the presence of neutrino inhomogeneities. As the cosmic string moves through the plasma the small magnetic field is amplified by the turbulence in the plasma. Relativistic charged particles which cross the magnetized wake of a cosmic string will therefore emit synchrotron radiation. The opening angle of the cosmic string is very small and so the wake appears like a relativistic jet. Assuming a homogeneous magnetic field in the wake of the string, we obtain the synchrotron emission from non thermal relativistic electrons in the wake of the string. The emitted radiation has a broad peak and is over a wide range of frequency. We show that the spectrum can be mapped to some of the unknown sources in different ranges of the current available catalogues.

The maximal gravitational mass of nonrotating neutron stars ($M_{\rm TOV}$) is one of the key parameters of compact objects and only loose bounds can be set based on the first principle. With reliable measurements of the masses and/or radii of the neutron stars, $M_{\rm TOV}$ can be robustly inferred from either the mass distribution of these objects or the reconstruction of the equation of state (EoS) of the very dense matter. For the first time we take the advantages of both two approaches to have a precise inference of $M_{\rm TOV}=2.25^{+0.08}_{-0.07}~M_\odot$ (68.3% credibility), with the updated neutron star mass measurement sample, the mass-tidal deformability data of GW170817, the mass-radius data of PSR J0030+0451 and PSR J0740+6620, as well as the theoretical information from the chiral effective theory ($\chi$EFT) and perturbative quantum chromodynamics (pQCD) at low and very high energy densities, respectively. This narrow credible range is benefited from the suppression of the high $M_{\rm TOV}$ by the pQCD constraint and the exclusion of the low $M_{\rm TOV}$ by the mass function. Three different EoS reconstruction methods are adopted separately, and the resulting $M_{\rm TOV}$ are found to be almost identical. This precisely evaluated $M_{\rm TOV}$ suggests that the EoS of neutron star matter is just moderately stiff and the $\sim 2.5-3M_\odot$ compact objects detected by the second generation gravitational wave detectors are most likely the lightest black holes.

Many astrophysical applications require efficient yet reliable forecasts of stellar evolution tracks. One example is population synthesis, which generates forward predictions of models for comparison with observations. The majority of state-of-the-art population synthesis methods are based on analytic fitting formulae to stellar evolution tracks that are computationally cheap to sample statistically over a continuous parameter range. Running detailed stellar evolution codes, such as MESA, over wide and densely sampled parameter grids is prohibitively expensive computationally, while stellar-age based linear interpolation in-between sparsely sampled grid points leads to intolerably large systematic prediction errors. In this work, we provide two solutions of automated interpolation methods that find satisfactory trade-off points between cost-efficiency and accuracy. We construct a timescale-adapted evolutionary coordinate and use it in a two-step interpolation scheme that traces the evolution of stars from zero age main sequence all the way to the end of core helium burning while covering a mass range from ${0.65}$ to $300 \, \mathrm{M_\odot}$. The feedforward neural network regression model (first solution) that we train to predict stellar surface variables can make millions of predictions, sufficiently accurate over the entire parameter space, within tens of seconds on a 4-core CPU. The hierarchical nearest neighbor interpolation algorithm (second solution) that we hard-code to the same end achieves even higher predictive accuracy, the same algorithm remains applicable to all stellar variables evolved over time, but it is two orders of magnitude slower. Our methodological framework is demonstrated to work on the MIST data set. Finally, we discuss prospective applications and provide guidelines how to generalize our methods to higher dimensional parameter spaces.

Many efforts have been done in recent years to probe the gas fraction evolution of massive quiescent galaxies (QGs); however, a clear picture has not yet been established. Recent spectroscopic confirmations at z>3 offer the chance to measure the residual gas reservoirs of massive galaxies a few hundreds of Myr after their death and to study how fast quenching proceeds in a highly star-forming Universe. Even so, stringent constraints at z$>$2 remain hardly accessible with ALMA when adopting molecular gas tracers commonly used for the quenched population. In this letter, we propose overcoming this impasse by using the carbon [CII] 158 $\mu$m emission line to systematically probe the gaseous budget of unlensed QGs at z>2.8, when these galaxies could still host non-negligible star formation on an absolute scale and when the line becomes best observable with ALMA (Bands 8 and 7). So far predominantly used for star-forming galaxies, this emission line is the best choice to probe the gas budget of spectroscopically confirmed QGs at $z>3$, reaching 2-4 and 13-30 times deeper than dust continuum (ALMA band 7) and CO(2-1)/(1-0) (VLA K-K$\alpha$ bands), respectively, at fixed integration time. Exploiting archival ALMA observations, we place conservative 3$\sigma$ upper limits on the molecular gas fraction (f$_{\rm{mol}}=M_{\rm{H_2}}/M_{\star}$) of ADF22-QG1 (f$_{\rm{mol}}$<21%), ZF-COS-20115 (f$_{\rm{mol}}$<3.2%), two of the best-studied high-z QGs in the literature, and GS-9209 (f$_{\rm{mol}}$<72%), the most distant massive QG discovered to date. The deep upper limit found for ZF-COS-20115 is 3 times lower than previously anticipated for high-z QGs suggesting, at best, the existence of a large scatter in the f$_{\rm{mol}}$ distribution of the first QGs. Lastly, we discuss the current limitations of the method and propose ways to mitigate some of them by exploiting ALMA bands 9 and 10.

These notes summarize the lectures about "Cosmic-ray propagation in extragalactic space and secondary messengers", focusing in particular on the interactions of cosmic-ray particles with the background photons in the Universe, including nuclear species heavier than hydrogen, and on the analytical computation of the expected cosmic-ray fluxes at Earth. The lectures were held at the Course 208 of the International School of Physics "Enrico Fermi" on "Foundations of Cosmic-Ray Astrophysics", in Varenna (Como, Italy) from June 23rd to June 29th, 2022. These notes are complementary to the content of the lectures held by Pasquale Dario Serpico at the same school.

Methyl cyanide (CH$_3$CN) is one of the most abundant and widely spread interstellar complex organic molecules (iCOMs). Several studies found that, in hot corinos, methyl cyanide and methanol abundances are correlated suggesting a chemical link, often interpreted as a synthesis of them on the interstellar grain surfaces. In this article, we present a revised network of the reactions forming methyl cyanide in the gas-phase. We carried out an exhaustive review of the gas-phase CH$_3$CN formation routes, propose two new reactions and performed new quantum mechanics computations of several reactions. We found that 13 of the 15 reactions reported in the databases KIDA and UDfA have incorrect products and/or rate constants. The new corrected reaction network contains 10 reactions leading to methyl cyanide. We tested the relative importance of those reactions in forming CH$_3$CN using our astrochemical model. We confirm that the radiative association of CH${_3}{^+}$ and HCN, forming CH$_{3}$CNH$^{+}$, followed by the electron recombination of CH$_{3}$CNH$^{+}$, is the most important CH$_3$CN formation route in both cold and warm environments, notwithstanding that we significantly corrected the rate constants and products of both reactions. The two newly proposed reactions play an important role in warm environments. Finally, we found a very good agreement between the CH$_3$CN predicted abundances with those measured in cold ($\sim$10 K) and warm ($\sim$90 K) objects. Unexpectedly, we also found a chemical link between methanol and methyl cyanide via the CH$_{3}^{+}$ ion, which can explain the observed correlation between the CH$_3$OH and CH$_3$CN abundances measured in hot corinos.

We present multi-wavelength photometry and spectroscopy of SN 2022jli, an unprecedented Type Ic supernova discovered in the galaxy NGC 157 at a distance of $\approx$ 23 Mpc. The multi-band light curves reveal many remarkable characteristics. Peaking at a magnitude of $g=15.11\pm0.02$, the high-cadence photometry reveals 12.5$\pm0.2\ $day periodic undulations superimposed on the 200 day supernova decline. This periodicity is observed in the light curves from nine separate filter and instrument configurations with peak-to-peak amplitudes of $\simeq$ 0.1 mag. This is the first time that repeated periodic oscillations, over many cycles, have been detected in a supernova light curve. SN 2022jli also displays an extreme early excess which fades over $\approx$ 25 days followed by a rise to a peak luminosity of $L_{\rm opt} = 10^{42.1}$ erg s$^{-1}$. Although the exact explosion epoch is not constrained by data, the time from explosion to maximum light is $\gtrsim$ 59 days. The luminosity can be explained by a large ejecta mass ($M_{\rm ej}\approx12\pm6$M$_{\odot}$) powered by $^{56}$Ni but we find difficulty in quantitatively modelling the early excess with circumstellar interaction and cooling. Collision between the supernova ejecta and a binary companion is a possible source of this emission. We discuss the origin of the periodic variability in the light curve, including interaction of the SN ejecta with nested shells of circumstellar matter and neutron stars colliding with binary companions.

When viewed from Earth, most of what we observe of a comet is dust. The influence of solar radiation pressure on the trajectories of dust particles depends on their cross-section to mass ratio. Hence solar radiation pressure acts like a mass spectrometer inside a cometary tail. The appearances of cometary dust tails have long been studied to obtain information on the dust properties, such as characteristic particle size and initial velocity when entering the tail. Over the past two decades, several spacecraft missions to comets have enabled us to study the dust activity of their targets at much greater resolution than is possible with a telescope on Earth or in near-Earth space, and added detail to the results obtained by the spacecraft visiting comet 1P/Halley in 1986. We now know that the dynamics of dust in the inner cometary coma is complex and includes a significant fraction of particles that will eventually fall back to the surface. The filamented structure of the near-surface coma is thought to result from a combination of topographic focussing of the gas flow, inhomogeneous distribution of activity across the surface, and projection effects. It is possible that some larger-than-centimetre debris contains ice when lifted from the surface, which can affect its motion. Open questions remain regarding the microphysics of the process that leads to the detachment and lifting of dust from the surface, the evolution of the dust while travelling away from the nucleus, and the extent to which information on the nucleus activity can be retrieved from remote observations of the outer coma and tail.

The conventional classification of Gamma-Ray Bursts (GRBs) as short or long bursts based on their duration is widely accepted as arising from different progenitor sources identified as compact object mergers and collapsars, respectively. However, recent observational shreds of evidence challenged this view, with signatures of collapsars in short GRBs and mergers in long GRBs. We conduct a comparative analysis of the characteristics of short and long GRBs, both at low and high redshifts, taking into account the locations and environments of their host galaxies. Our analysis suggests that some short GRBs at higher redshifts exhibit features similar to long GRBs, indicating a possible collapsar origin. Further investigation, utilizing multi-messenger observations, could provide a resolution to this issue.

This study investigates the environments and characteristics of Gamma-Ray Bursts (GRBs) exhibiting very high energy (VHE) emission. Recent detections of VHE emission, up to TeV energies, challenge synchrotron-only emission models and particle acceleration concepts in GRBs. Until now, only a handful of GRBs have been detected in the VHE range. We compare the number densities of the circumburst medium of VHE-detected GRBs to check if the environment impacts the VHE emission. This shows that these GRBs have environments similar to the larger population of GRBs. We employ machine learning algorithms to create two-dimensional embeddings of GRB prompt emission light curves from the {\it Swift}-BAT catalog. VHE-detected GRBs are located across the map, indicating that VHE emission does not favour any particular cluster. These findings indicate that VHE-detected GRBs do not show any peculiar characteristics other than the observational detection of VHE photons. Future detections will increase the sample size required for a rigorous understanding of the origin of VHE emission in GRBs.

Electron capture (EC) decay relies on attachment and stripping cross-sections, that in turn, depend on the atomic number of the nucleus. We revisit the impact of EC decay in the context of the high-precision cosmic-ray fluxes measured by the AMS-02 experiment. We derive the solution of the steady-state fluxes in a 1D thin disk model including EC decay. We compare our results with relevant elemental and isotopic fluxes and evaluate the impact of this process, given the precision of recent AMS-02, ACE-CRIS, SuperTIGER, and Voyager data. We find this impact to be at the level or larger than the precision of recently collected data for several species, e.g. $_{31}$Ga and $_{33}$As, indicating that EC decay must be properly taken into account in the calculation.

We explore the feasibility and potential characteristics of photosynthetic light-harvesting on exo-planets orbiting in the habitable zone of low mass stars ($< 1$ M$_{\odot}$). As stellar temperature, $T_{s}$, decreases, the irradiance maximum red-shifts out of the $400 \textrm{nm} \leq \lambda < 750$ nm range of wavelengths that can be utilized by \emph{oxygenic} photosynthesis on Earth. However, limited irradiance in this region does not preclude oxygenic photosynthesis and Earth's plants, algae and cyanobacteria all possess very efficient \emph{light-harvesting antennae} that facilitate photosynthesis in very low light. Here we construct general models of photosynthetic light-harvesting structures to determine how an oxygenic photosystem would perform in different irradiant spectral fluxes. We illustrate that the process of light-harvesting, capturing energy over a large antenna and concentrating it into a small \emph{reaction centre}, must overcome a fundamental \emph{entropic barrier}. We show that a plant-like antenna cannot be adapted to the light from stars of $T_{s}<3400$ K, as increasing antenna size offers diminishing returns on light-harvesting. This can be overcome if one introduces a slight \emph{enthalpic gradient}, to the antenna. Interestingly, this strategy appears to have been adopted by Earth's oxygenic cyanobacteria, and we conclude that \emph{bacterial} oxygenic photosynthesis is feasible around even the lowest mass M-dwarf stars.

With the advancement of technology, machine learning-based analytical methods have pervaded nearly every discipline in modern studies. Particularly, a number of methods have been employed to estimate the redshift of gamma-ray loud active galactic nuclei (AGN), which are a class of supermassive black hole systems known for their intense multi-wavelength emissions and violent variability. Determining the redshifts of AGNs is essential for understanding their distances, which, in turn, sheds light on our current understanding of the structure of the nearby universe. However, the task involves a number of challenges such as the need for meticulous follow-up observations across multiple wavelengths and astronomical facilities. In this study, we employ a simple yet effective deep learning model with a single hidden layer having $64$ neurons and a dropout of 0.25 in the hidden layer, on a sample of AGNs with known redshifts from the latest AGN catalog, 4LAC-DR3, obtained from Fermi-LAT. We utilized their spectral, spatial, and temporal properties to robustly predict the redshifts of AGNs as well quantify their associated uncertainties, by modifying the model using two different variational inference methods. We achieve a correlation coefficient of 0.784 on the test set from the frequentist model and 0.777 and 0.778 from both the variants of variational inference, and, when used to make predictions on the samples with unknown redshifts, we achieve mean predictions of 0.421, 0.415 and 0.393, with standard deviations of 0.258, 0.246 and 0.207 from the models, respectively.

Mini-EUSO is a small, near-UV telescope observing the Earth and its atmosphere from the International Space Station. The time resolution of 2.5 microseconds and the instantaneous ground coverage of about $320\times 320$ km$^2$ allows it to detect some Transient Luminous Events, including Elves. Elves, with their almost circular shape and a radius expanding in time form cone-like structures in space-time, which are usually easy to be recognised by the eye, but not simple to filter out from the myriad of other events, many of them not yet categorised. In this work, we present a fast and efficient approach for detecting Elves in the data using a 3D CNN-based one-class classifier.

The long-standing paradox of the linear polarization signal of the Na i D1 line was recently resolved by accounting for the atom's hyperfine structure and the detailed spectral structure of the incident radiation field. That modeling relied on the simplifying angle-averaged (AA) approximation for partial frequency redistribution (PRD) in scattering, which potentially neglects important angle-frequency couplings. This work aims at evaluating the suitability of a PRD-AA modeling for the D1 and D2 lines through comparisons with general angle-dependent (AD) PRD calculations, both in the absence and presence of magnetic fields. We solved the radiative transfer problem for polarized radiation in a one-dimensional semi-empirical atmospheric model with microturbulent and isotropic magnetic fields, accounting for PRD effects, comparing PRD-AA and PRD-AD modelings. The D1 and D2 lines are modeled separately as two-level atomic system with hyperfine structure. The numerical results confirm that a spectrally structured radiation field induces linear polarization in the D1 line. However, the PRD-AA approximation greatly impacts the Q/I shape, producing an antisymmetric pattern instead of the more symmetric PRD-AD one, while presenting a similar sensitivity to magnetic fields between 10 and 200 G. Under the PRD-AA approximation, the Q/I profile of the D2 line presents an artificial dip in its core, which is not found for the PRD-AD case. We conclude that accounting for PRD-AD effects is essential to suitably model the scattering polarization of the Na i D lines. These results bring us closer to exploiting the full diagnostic potential of these lines for the elusive chromospheric magnetic fields.

Using an analytic model, we derive the eigenfrequencies for thermal Rossby waves that are trapped radially and latitudinally in an isentropically stratified atmosphere. We ignore the star's curvature and work in an equatorial f-plane geometry. The propagation of inertial waves is found to be sensitive to the relative direction of the wave vector to the zonal direction. Prograde propagating thermal Rossby waves are naturally trapped in the radial direction for frequencies above a critical threshold, which depends on the angle of propagation. Below the threshold frequency, there exists a continuous spectrum of prograde and retrograde inertial waves that are untrapped in an isentropic atmosphere, but can be trapped by gradients in the specific entropy density such as occurs in a stellar convection zone. Finally, we discuss the implications of these waves on recent observations of inertial oscillations in the Sun, as well as in numerical simulations.

VERITAS is an imaging atmospheric Cherenkov telescope (IACT) array most sensitive to gamma rays in the very-high-energy (VHE) energy band (85 GeV - 30 TeV). As a part of its active galactic nuclei (AGN) program, VERITAS focuses on the identification and follow-up of AGN flares reported by other multiwavelength observatories. Between October 15th and October 19th, 2020, VERITAS followed up on the Fermi-LAT and MAGIC detections of a flare of the intermediate-frequency-peaked BL Lacertae (IBL) object, B2 1811+31, located at a redshift of z=0.117. In this work, we present preliminary scientific results from the analysis of B2 1811+31's 2020 flare, including the corresponding Fermi-LAT light curve and VERITAS detection analysis.

We report a non-detection of the [OI] 63-um emission line from the z = 6.03 galaxy G09.83808 using ALMA Band 9 observations, refuting the previously claimed detection with APEX by (Rybak et al. 2020); the new upper limit on the [OI] 63-um flux is almost 20-times lower. [OI] 63-um line could be a powerful tracer of neutral gas in the Epoch of Reionisation: yet our null result shows that detecting [OI] 63-um from z$\geq$6 galaxies is more challenging than previously hypothesised.

The interaction of a supermassive black hole with the matter of an accretion disk in the presence of a magnetic field is the key mechanism of energy release in active galactic nuclei. However, determining the physical parameters of this system, such as the spin and mass of the black hole, the shape and parameters of the rotation of the accretion disk, and the geometry of the magnetic field in the accretion disk is a complex and not completely solved problem. We have previously shown, based on our numerical models, that these estimates can be obtained from just three parameters: the black hole mass, bolometric luminosity, and optical polarization. In this paper, we estimate the accretion disk and black hole parameters for a sample of 14 type 1 Seyfert galaxies. Using the spectropolarimetric data obtained by us, we selected only those objects in which the polarization of optical radiation is generated mainly by the mechanism in the accretion disk. Despite the small statistics, our results for such a sample are consistent with our previous conclusions and show a discrepancy between the disk magnetic field parameters and the classical Shakura-Sunyaev disk model.

We apply machine learning algorithms to classify Infrared (IR)-selected targets for NASA's upcoming SPHEREx mission. In particular, we are interested in classifying Young Stellar Objects (YSOs), which are essential for understanding the star formation process. Our approach differs from previous work, which has relied heavily on broadband color criteria to classify IR-bright objects, and are typically implemented in color-color and color-magnitude diagrams. However, these methods do not state the confidence associated with the classification and the results from these methods are quite ambiguous due to the overlap of different source types in these diagrams. Here, we utilize photometric colors and magnitudes from seven near and mid-infrared bands simultaneously and employ machine and deep learning algorithms to carry out probabilistic classification of YSOs, Asymptotic Giant Branch (AGB) stars, Active Galactic Nuclei (AGN) and main-sequence (MS) stars. Our approach also sub-classifies YSOs into Class I, II, III and flat spectrum YSOs, and AGB stars into carbon-rich and oxygen-rich AGB stars. We apply our methods to infrared-selected targets compiled in preparation for SPHEREx which are likely to include YSOs and other classes of objects. Our classification indicates that out of $8,308,384$ sources, $1,966,340$ have class prediction with probability exceeding $90\%$, amongst which $\sim 1.7\%$ are YSOs, $\sim 58.2\%$ are AGB stars, $\sim 40\%$ are (reddened) MS stars, and $\sim 0.1\%$ are AGN whose red broadband colors mimic YSOs. We validate our classification using the spatial distributions of predicted YSOs towards the Cygnus-X star-forming complex, as well as AGB stars across the Galactic plane.

This paper presents the final sample and data release of the INvestigating Stellar Population In RElics (INSPIRE) project, comprising 52 ultra-compact massive galaxies (UCMGs) observed with the ESO-VLT X-Shooter spectrograph. We measure integrated stellar velocity dispersion, [Mg/Fe] abundances, ages, and metallicities for all the INSPIRE objects. We thus infer star formation histories and confirm the existence of a degree of relicness (DoR), defined in terms of the fraction of stellar mass formed by $z=2$, the cosmic time at which a galaxy has assembled 75% of its mass and the final assembly time. Objects with a high DoR assembled their stellar mass at early epochs, while low-DoR objects show a non-negligible fraction of later-formed populations and hence a spread in ages and metallicities. A higher DoR correlates with larger [Mg/Fe], super-solar metallicity, and larger velocity dispersion values. The 52 UMCGs span a large range of DoR from 0.83 to 0.06, with 38 of them having formed more than 75% of their mass by $z=2$, which translates in a lower limit to the number density of relics at $z\sim0.3$ of $\log \rho \approx 2.8 \times 10^{-7} \text{Mpc}^{-3}$.. Nine relics are extreme (DoR$>0.7$), since they formed almost the totality ($>98\%$) of their stellar mass by redshift $z=2$. With INSPIRE, we have increased the number of fully confirmed relics by more than a factor of 10, also pushing the redshift boundaries, hence building the first sizeable sample of relics outside the local Universe, opening up an important window to explain the mass assembly of massive galaxies in the high-z Universe.

Our goal is to study the gravitational effects caused by the passage of the Large Magellanic Cloud (LMC) in its orbit on the stellar halo of the Milky Way (MW). We employed the Gaia Data Release 3 to construct a halo tracers data set consisting of K-Giant stars and RR-Lyrae variables. Additionally, we have compared the data with a theoretical model to estimate the DM subhalo mass. We have improved the characterisation of the local wake and the collective response due to the LMC orbit. On the other hand, we have estimated for the first time the dark subhalo mass of the Large Magellanic Cloud, of the order of $2\times 10^{11}$ M$_{\odot}$, comparable to previously reported values in the literature.

Equations of motion are derived for (visco)elastic, self-gravitating, and variably-rotating planets. The equations are written using a decomposition of the elastic motion that separates the body's elastic deformation from its net translational and rotational motion as far as possible. This separation is achieved by introducing degrees of freedom that represent the body's rigid motions; it is made precise by imposing constraints that are physically motivated and should be practically useful. In essence, a Tisserand frame is introduced exactly into the equations of solid mechanics. The necessary concepts are first introduced in the context of a solid body, motivated by symmetries and conservation laws, and the corresponding equations of motion are derived. Next, it is shown how those ideas and equations of motion can readily be extended to describe a layered fluid--solid body. A possibly new conservation law concerning inviscid fluids is then stated. Thereafter the equilibria and linearisation of the fluid--solid equations of motion are discussed, along with new equations for use within normal-mode coupling calculations and other Galerkin methods. Finally, the extension of these ideas to the description of multiple, interacting fluid--solid planets is qualitatively discussed.

Eicheon properties are discussed. It is shown that the eicheon surface allows setting a boundary condition for the vacuum polarization and obtaining a solution describing the dark matter tail in the Milky Way Galaxy. That is, the dark matter in the Milky Way Galaxy is explained as the F-type of vacuum polarization, which could be treated as dark radiation. The model presented is spherically symmetric, but a surface density of a baryonic galaxy disk is taken into account approximately by smearing the disk over a sphere. This allows the reproduction of the large distance shape of the Milky Way Galaxy rotational curve. Andromeda Galaxy's rotational curve is also discussed.

We investigate the hypothetical X17 boson on neutron stars and Quark Stars (QSs) using various hadronic Equation of States (EoSs) with phenomenological or microscopic origin. Our aim is to set realistic constraints on its coupling constant and the mass scaling, with respect to causality and various possible upper mass limits and the dimensionless tidal deformability $\Lambda_{1.4}$. In particular, we pay special attention on two main phenomenological parameters of the X17, the one is related to the coupling constant $\mathrm{g}$ that it has with hadrons or quarks and the other with the in-medium effects through the regulator $\mathrm{C}$. Both are very crucial concerning the contribution on the total energy density and pressure. In the case of considering the X17 as a carrier of nuclear force in Relativistic Mean Field (RMF) theory, an admixture into vector boson segment was constrained by 20\% and 30\%. In our investigation, we came to the general conclusion that the effect of the hypothetical X17 both on neutron and QSs constrained mainly by the causality limit, which is a specific property of each EoS. Moreover, it depends on the interplay between the main two parameters that is the interaction coupling $\mathrm{g}$ and the in-medium effects regulator $\mathrm{C}$. These effects are more pronounced in the case of QSs concerning all the bulk properties.

Gravitational waveforms play a crucial role in comparing observed signals to theoretical predictions. However, obtaining accurate analytical waveforms directly from general relativity remains challenging. Existing methods involve a complex blend of post-Newtonian theory, effective-one-body formalism, numerical relativity, and interpolation, introducing systematic errors. As gravitational wave astronomy advances with new detectors, these errors gain significance, particularly when testing general relativity in the non-linear regime. A recent development proposes a novel approach to address this issue. By deriving precise constraints - or balance laws - directly from full non-linear GR, this method offers a means to evaluate waveform quality, detect template weaknesses, and ensure internal consistency. Before delving into the intricacies of balance laws in full non-linear general relativity, we illustrate the concept using a detailed mechanical analogy. We'll examine a dissipative mechanical system as an example, demonstrating how mechanical balance laws can gauge the accuracy of approximate solutions in capturing the complete physical scenario. While mechanical balance laws are straightforward, deriving balance laws in electromagnetism and general relativity demands a rigorous foundation rooted in mathematically precise concepts of radiation. Following the analogy with electromagnetism, we derive balance laws in general relativity. As a proof of concept, we employ an analytical approximate waveform model, showcasing how these balance laws serve as a litmus test for the model's validity.