Papers for Tuesday, Feb 21 2023

The Juno mission has provided measurements of Jupiter s gravity field with an outstanding level of accuracy, leading to better constraints on the interior of the planet. Improving our knowledge of the internal structure of Jupiter is key to understanding its formation and evolution but is also important in the framework of exoplanet exploration. In this study, we investigated the differences between the state-of-the-art equations of state and their impact on the properties of interior models. Accounting for uncertainty on the hydrogen and helium equation of state, we assessed the span of the interior features of Jupiter. We carried out an extensive exploration of the parameter space and studied a wide range of interior models using Markov chain Monte Carlo (MCMC) simulations. To consider the uncertainty on the equation of state, we allowed for modifications of the equation of state in our calculations. Our models harbour a dilute core and indicate that Jupiter s internal entropy is higher than what is usually assumed from the Galileo probe measurements. We obtain solutions with extended dilute cores, but contrary to other recent interior models of Jupiter, we also obtain models with small dilute cores. The dilute cores in such solutions extend to 20% of Jupiter s mass, leading to better agreement with formation evolution models. We conclude that the equations of state used in Jupiter models have a crucial effect on the inferred structure and composition. Further explorations of the behaviour of hydrogen helium mixtures at the pressure and temperature conditions in Jupiter will help to constrain the interior of the planet, and therefore its origin.

We perform general relativistic simulations of magnetized, accreting disks onto spinning binary black holes (BHBHs) with different mass ratios (MRs). The magnitude of the individual BH spins are all $\chi= 0.26$ and lie either along the initial orbital plane or $45^\circ$ above it. We evolve these systems throughout the inspiral, merger and postmerger phases to identify the impact of the BH spins and the MR on any jet and their electromagnetic (EM) signatures. We find that incipient jets are launched from both BHs regardless of the MR and along the spin directions as long as the force-free parameter $B^2/(8\,\pi\rho_0)$ in the funnel and above their poles is larger than one. At large distances the two jets merge into a single one what may prevent the EM detection of individual jets. As the accretion rate reaches a quasistationary state during predecoupling, we observe a sudden amplification of the outgoing Poynting luminosity that depends on the MR. Following merger, the sudden change in the direction of the spin of the BH remnant with respect to the spins of its progenitors causes a reorientation of the jet, which drives a single, high-velocity, outward narrow beam collimated by a tightly wound, helical Bfield which, in turn, boosts the Poynting luminosity. This effect is nearly MR independent. During this process, a kink is produced in the Bfield lines, confining the jet. The kink propagates along the jet but rapidly decays, leaving no memory of the spin-shift. Our results suggest that the merger of misaligned, low-spinning, BHBH mergers in low-mass disks may not provide a viable scenario to explain X-shaped radio galaxies if other features are not taken into account. However, the sudden changes in the outgoing luminosity at merger may help to identify mergers of BHs in active galactic nuclei, shedding light on BH growth mechanisms and the observed co-evolution of their host galaxies.

Stars are known to be more active when they are young, resulting in a strong correlation between age and photometric variability. The amplitude variation between stars of a given age is large, but the age-variability relation becomes strong over large groups of stars. We explore this relation using the excess photometric uncertainty in Gaia photometry ($Var_{G}$, $Var_{BP}$, and $Var_{RP}$) as a proxy for variability. The metrics follow a Skumanich-like relation, scaling as $\simeq t^{-0.4}$. By calibrating against a set of associations with known ages, we show how $Var$ of population members can predict group ages within 10-20% for associations younger than $\simeq$2.5 Gyr. In practice, age uncertainties are larger, primarily due to finite group size. The index is most useful at the youngest ages ($<$100 Myr), where the uncertainties are comparable to or better than derived from a color-magnitude diagram. The index is also widely available, easy to calculate, and can be used at intermediate ages where there are few or no pre- or post-main-sequence stars. We further show how $Var$ can be used to find new associations and test if a group of co-moving stars is a real co-eval population. We apply our methods on the Theia groups within 350 pc and find $\gtrsim$90% are inconsistent with drawing stars from the field and $\simeq$80% have variability ages consistent with those derived from the CMD. Our finding suggest the great majority of these groups contain real populations.

The recent discovery of a spiral pattern in the vertical kinematic structure in the solar neighborhood provides a prime opportunity to study non-equilibrium dynamics in the Milky Way from local stellar kinematics. Furthermore, results from simulations indicate that even in a limited volume, differences in stellar orbital histories allow us to trace variations in the initial perturbation across large regions of the disk. We present $\texttt{ESCARGOT}$, a novel algorithm for studying these variations in both simulated and observed data sets. $\texttt{ESCARGOT}$ automatically extracts key quantities from the structure of a given phase spiral, including the time since perturbation and the perturbation mode. We test $\texttt{ESCARGOT}$ on simulated data and show that it is capable of accurately recovering information about the time since the perturbation occurred as well as subtle differences in phase spiral morphology due to stellar location in the disk at the time of perturbation. We apply $\texttt{ESCARGOT}$ to kinematic data from data release 3 of the ${\it Gaia}$ mission in bins of guiding radius. We show that similar structural differences in morphology occur in the ${\it Gaia}$ phase spirals as a function of stellar orbital history. These results indicate that the phase spirals are the product of a complex dynamical response in the disk with large-scale coupling between different regions of phase space.

We present a study of the metal-enriched halo gas, traced using MgII and [OII] emission lines, in two large, blind galaxy surveys conducted using Multi Unit Spectroscopic Explorer (MUSE) optical integral field unit observations, namely the MUSE Analysis of Gas around Galaxies (MAGG) and the MUSE Ultra Deep Field (MUDF). By stacking a sample of ~600 galaxies with stellar masses M* ~10^{6-12} Msun (median M* ~2x10^9 Msun) at redshifts z=0.7-1.5 (median z~1), we characterize for the first time the average metal line emission from a general population of galaxy haloes. The MgII and [OII] line emission extends farther out than the stellar continuum emission around galaxies, on average out to ~25 kpc and ~45 kpc, respectively, at a surface brightness (SB) level of 10^{-20} erg/s/cm2/arcsec2. The radial profile of the MgII SB is shallower than that of the [OII], suggesting that the resonant MgII emission is affected by dust and radiative transfer effects. The [OII] to MgII SB ratio is ~3 over ~20-40 kpc, also indicating a significant in situ origin of the extended metal emission in the inner halo. The average profiles are intrinsically brighter by a factor ~2-3 and more radially extended by a factor of ~1.3 at 1.0 < z <= 1.5 than at 0.7 <= z <= 1.0. The average extent of the metal emission also increases independently with increasing stellar mass and in overdense group environments. When considering individual detections, we find extended [OII] emission up to ~50 kpc around ~30-40 percent of the group galaxies, and extended ~30-40 kpc MgII emission around two z~1 quasars in groups, which could arise from outflows or environmental processes.

It has very recently been claimed that the neutrino-assisted early dark energy model -- a promising resolution of the Hubble tension that can ameliorate the theoretical fine-tuning and coincidence problems that plague other theories -- does not provide natural or cosmologically interesting results. In this short paper, we show that these conclusions are incorrect for three reasons. First, we identify errors in the calculations. Second, we dispute the definition in of what constitutes an 'interesting' and 'natural' model. Finally, we demonstrate that the conclusions of were arrived at without fully exploring the full parameter space of the model. Neutrino-assisted early dark energy remains a natural and interesting potential resolution of the Hubble tension that merits further study.

Theoretical studies predict that the most significant growth of supermassive black holes occurs in late-stage mergers, coinciding with the manifestation of dual active galactic nuclei (AGNs), and both major and minor mergers are expected to be important for dual AGN growth. In fact, dual AGNs in minor mergers should be signposts for efficient minor merger-induced SMBH growth for both the more and less massive progenitor. We identified two candidate dual AGNs residing in apparent minor mergers with mass ratios of $\sim$1:7 and $\sim$1:30. SDSS fiber spectra show broad and narrow emission lines in the primary nuclei of each merger while only a narrow [O III] emission line and a broad and prominent H$\alpha$/[N II] complex is observed in the secondary nuclei. The FWHMs of the broad H$\alpha$ lines in the primary and secondary nuclei are inconsistent in each merger, suggesting that each nucleus in each merger hosts a Type 1 AGN. However, spatially-resolved LBT optical spectroscopy reveal rest-frame stellar absorption features, indicating the secondary sources are foreground stars and that the previously detected broad lines are likely the result of fiber spillover effects induced by the atmospheric seeing at the time of the SDSS observations. This study demonstrates for the first time that optical spectroscopic searches for Type 1/Type 1 pairs similarly suffer from fiber spillover effects as has been observed previously for Seyfert 2 dual AGN candidates. The presence of foreground stars may not have been clear if an instrument with more limited wavelength range or limited sensitivity had been used.

Most of the scientific instrumentation as well as the tracking systems and the Shack- Hartmann wavefront analysers at the Italian National Telescope Galileo use CCDs as detectors. The characterization of detectors is of fundamental importance for their correct utilization in scientific instrumentation. We report on the measurement of the electro-optical characteristics of CCDs that will be used in the scientific instrumentation at the Italian National Telescope. In particular we will show and compare the quantum e{\AE}ciency, the charge transfer e{\AE}ciency, the dark current, the read out noise the uniformity and the linearity of two sets of CCDs manufactured by EEV and LORAL. Finally, we will show the preliminary tests done at the telescope with the optical imager that has a mosaic of two EEV chips.

Neutrino mass constraints are a primary focus of current and future large-scale structure (LSS) surveys. Non-linear LSS models rely heavily on cosmological simulations -- the impact of massive neutrinos should therefore be included in these simulations in a realistic, computationally tractable, and controlled manner. A recent proposal to reduce the related computational cost employs a symmetric neutrino momentum sampling strategy in the initial conditions. We implement a modified version of this strategy into the Hardware/Hybrid Accelerated Cosmology Code (HACC) and perform convergence tests on its internal parameters. We illustrate that this method can impart $\mathcal{O}(1\%)$ numerical artifacts on the total matter field on small scales, similar to previous findings, and present a method to remove these artifacts using Fourier-space filtering of the neutrino density field. Moreover, we show that the converged neutrino power spectrum does not follow linear theory predictions on relatively large scales at early times at the $15\%$ level, prompting a more careful study of systematics in particle-based neutrino simulations. We also present an improved method for backscaling linear transfer functions for initial conditions in massive neutrino cosmologies that is based on achieving the same relative neutrino growth as computed with Boltzmann solvers. Our self-consistent backscaling method yields sub-percent accuracy in the total matter growth function. Comparisons for the non-linear power spectrum with the Mira-Titan emulator at a neutrino mass of $m_{\nu}=0.15~\mathrm{eV}$ are in very good agreement with the expected level of errors in the emulator and in the direct N-body simulation.

We present the results regarding the analysis of an intensive monitoring of the Active Galactic Nucleus (AGN) NGC 7469. We observed the source for 4 months with almost daily cadence in the ugriz bands, using the IO:O on the Liverpool Telescope. We measured the lags with respect to the u band and found a clear change of the lag spectrum between the first and the second half of the campaign. Given that the source varies on different timescales during these two segments, it is likely that different components are dominating the variability at different times. This result further confirms that reverberation models require a more complex geometry than a static illuminating point source and that particular attention has to be given in the interpretation of these delays.

Thermal energies deposited by OB stellar clusters in starburst galaxies lead to the formation of galactic superwinds. Multi-wavelength observations of starburst-driven superwinds pointed at complex thermal and ionization structures which cannot adequately be explained by simple adiabatic assumptions. In this study, we perform hydrodynamic simulations of a fluid model coupled to radiative cooling functions, and generate time-dependent non-equilibrium photoionization models to predict physical conditions and ionization structures of superwinds using the MAIHEM atomic and cooling package built on the program FLASH. Time-dependent ionization states and physical conditions produced by our simulations are used to calculate the emission lines of superwinds for various parameters, which allow us to explore implications of non-equilibrium ionization for starburst regions with potential radiative cooling.

This chapter presents an overview of the recent progress on spectroscopic observations of metal-poor stars with r-process element signatures found in the Milky Way's stellar halo and satellite dwarf galaxies. Major empirical lessons related to the origins of the r-process are discussed, including the universality of the observed r-process pattern and deviations from universality among the light r-process elements and actinides. Different astrophysical sites of the r-process based on theoretical expectations are presented, including common and rare supernovae and neutron star mergers. A major distinguishing factor between r-process sites is their delay time distribution. The best constraints on the detailed r-process pattern come from Galactic halo r-process stars, but these cannot provide information on the environment of the stars' birth gas clouds. Studying r-process enrichment within dwarf galaxies can remedy the situation despite the fact that high-resolution spectroscopic observations of individual stars in these systems are very difficult to obtain. A general overview of dwarf galaxy properties and chemical evolution expectations depending on their mass and star formation duration is provided. The r-process trends depend on the stellar mass and star formation durations of dwarf galaxies in a way that clearly shows that the r-process is rare, prolific, and has both prompt and delayed sources. This work complements ongoing theoretical heavy-element nucleosynthesis explorations and experimental measurements of the properties of r-process nuclei, such as with the Facility for Rare Isotope Beams.

We present the measurements of the small-scale clustering for the emission line galaxy (ELG) sample from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) in the Sloan Digital Sky Survey IV (SDSS-IV). We use conditional abundance matching method to interpret the clustering measurements from $0.34h^{-1}\textrm{Mpc}$ to $70h^{-1}\textrm{Mpc}$. In order to account for the correlation between properties of emission line galaxies and their environment, we add a secondary connection between star formation rate of ELGs and halo accretion rate. Three parameters are introduced to model the ELG [OII] luminosity and to mimic the target selection of eBOSS ELGs. The parameters in our models are optimized using Markov Chain Monte Carlo (MCMC) method. We find that by conditionally matching star formation rate of galaxies and the halo accretion rate, we are able to reproduce the eBOSS ELG small scale clustering within 1$\sigma$ error level. Our best fit model shows that the eBOSS ELG sample only consists of $\sim 12\%$ of all star-forming galaxies, and the satellite fraction of eBOSS ELG sample is 19.3\%. We show that the effect of assembly bias is $\sim20\%$ on the two-point correlation function and $\sim5\%$ on the void probability function at scale of $r\sim 20 h^{-1}\rm Mpc$.

One of the open questions following the discovery of GW170817 is whether neutron star mergers are the only astrophysical sites capable of producing r-process elements. Simulations have shown that 0.01-0.1M$_\odot$ of r-process material could be generated in the outflows originating from the accretion disk surrounding the rapidly rotating black hole that forms as a remnant to both neutron star mergers and collapsing massive stars associated with long-duration gamma-ray bursts (collapsars). The hallmark signature of r-process nucleosynthesis in the binary neutron star merger GW170817 was its long-lasting near-infrared emission, thus motivating a systematic photometric study of the light curves of broadlined stripped-envelope (Ic-BL) supernovae (SNe) associated with collapsars. We present the first systematic study of 25 SNe Ic-BL -- discovered with the Zwicky Transient Facility and from the literature -- in the optical/near-infrared bands to determine what quantity of r-process material, if any, is synthesized in these explosions. Using semi-analytic models designed to account for r-process production in SNe Ic-BL, we perform light curve fitting to derive constraints on the r-process mass for these SNe. We also perform independent light curve fits to models without r-process. We find that the r-process-free models are a better fit to the light curves of the objects in our sample. Thus we conclude that there is no compelling evidence of r-process enrichment in any of our objects. Further high-cadence infrared photometric studies and nebular spectroscopic analysis would be sensitive to smaller quantities of r-process ejecta mass or indicate whether all collapsars are completely devoid of r-process nucleosynthesis.

Starspots and stellar flares are indicators of stellar magnetic activity.The magnetic energy stored around spots is thought to be the origin of flares, but the connection is not completely understood. To investigate the relation between spot locations deduced from the light curves and occurrence of flares therein, we perform starspot modeling for TESS light curves of three M-dwarf flare stars, AU Mic, YZ CMi, and EV Lac, using the code implemented in Paper I. The code enables to deduce multiple stellar/spot parameters by the adaptive parallel tempering algorithm efficiently. We found that flare occurrence frequency is not necessarily correlated with the rotation phases of the light curve for each star. The result of starspot modeling shows that either spot is always visible to the line of sight in all phases, and we suggest that this can be one of the reasons that there is no or less correlation between rotation phases and flare frequency. In addition, the amplitude and shape of the light curve for AU Mic and YZ CMi have varied in two years between different TESS Cycles. The result of starspot modeling suggests that this can be explained by the variations of spot size and latitude.

The excess temperature of the solar corona over the photosphere poses a challenge. Multiple energetic events contribute to maintaining the corona at such high temperatures. The energy released in different events can vary across several orders of magnitude. Large energy events of geomagnetic importance like flares and coronal mass ejections (CMEs) contribute little to the global energetics of the solar corona. Therefore, events with several (9-10) orders of magnitudes of lower energy, with much higher frequency of occurrence, need to be studied in great detail. Observations suggest that these impulsive events with different energies follow a power-law distribution, indicating a common underlying mechanism. We perform observation-motivated modeling of coronal loops (magnetic flux tubes) to understand the energetics of these small transient events and their similarity with impulsive events like flares. This thesis uses the EBTEL code based on the 0D hydrodynamical description of coronal loops. This approach is appropriate for getting quick estimates of the energetics of the system over a wide range of parameters. We then discuss the improvement of EBTEL to make it suitable over a broader range of parameters. This is followed by using improved EBTEL to explore the possibility of simulating impulsive events of different energy generated using a single power-law distribution. Comparison between observed emissions from various components of multi-thermal plasma and hydrodynamical models suggest the heating to be impulsive. Since field-aligned flows induced due to impulsive events are a crucial part of our modeling of coronal loops, we discuss the implications of such flows in the context of transition region heating.

Molecular hydrogen clouds are a key component of the interstellar medium because they are the birthplaces for stars. They are embedded in atomic gas that pervades the interstellar space. However, the details of how molecular clouds assemble from and interact with the atomic gas are still largely unknown. As a result of new observations of the 158~$\mu$m line of ionized carbon CII in the Cygnus region within the FEEDBACK program on SOFIA (Stratospheric Observatory for Infrared Astronomy), we present compelling evidence that CII unveils dynamic interactions between cloud ensembles. This process is neither a head-on collision of fully molecular clouds nor a gentle merging ofonly atomic clouds. Moreover, we demonstrate that the dense molecular clouds associated with the DR21 and W75N star-forming regions and a cloud at higher velocity are embedded in atomic gas and all components interact over a large range of velocities (20 km/s). The atomic gas has a density of 100 cm$^{-3}$ and a temperature of 100 K. We conclude that the CII 158 $\mu$m line is an excellent tracer to witness the processes involved in cloud interactions and anticipate further detections of this phenomenon in other regions

The LIGO/Virgo detected a gravitational wave (GW) event, named GW200224_222234 (a.k.a. S200224ca) and classified as a binary-black-hole coalescence, on February 24, 2020. Given its relatively small localization skymap (71 deg$^2$ for a 90% credible region; revised to 50 deg$^2$ in GWTC-3), we performed target-of-opportunity observations using the Subaru/Hyper Suprime-Cam (HSC) in the $r2$- and $z$-bands. Observations were conducted on February 25 and 28 and March 23, 2020, with the first epoch beginning 12.3 h after the GW detection. The survey covered the highest probability sky area of 56.6 deg$^2$, corresponding to a 91% probability. This was the first deep follow-up ($m_{r}\gtrsim24, m_{z}\gtrsim23$) for a binary-black-hole merger covering $>$90% of the localization. By performing image subtraction and candidate screening including light curve fitting with transient templates and examples, we found 22 off-nucleus transients that were not ruled out as the counterparts of GW200224_222234 with only our Subaru/HSC data. We also performed GTC/OSIRIS spectroscopy of the probable host galaxies for five candidates; two are likely to be located within the 3D skymap, whereas the others are not. In conclusion, 19 transients remain as possible optical counterparts of GW200224_222234; however, we could not identify a unique promising counterpart. If there are no counterparts in the remaining candidates, the upper limits of optical luminosity are $\nu L_{\nu} < 5.2^{+2.4}_{-1.9}\times 10^{41}$ erg s$^{-1}$ and $\nu L_{\nu} < 1.8^{+0.8}_{-0.6}\times 10^{42}$ erg s$^{-1}$ in the $r2$- and $z$-bands, respectively, at $\sim$12 h after GW detection. We also discuss improvements in the strategies of optical follow-ups for future GW events.

Hard X-/soft gamma-ray astronomy is a crucial field for transient, nuclear and multimessenger astrophysics. However, the spatial localization, imaging capabilities and sensitivity of the measurements are strongly limited for the energy range > 70 keV. To overcome these limitations, we have proposed a mission concept, ASTENA, submitted to ESA for its program Voyage 2050. We will report on a pathfinder of ASTENA, that we intend to propose to ASI as an Italian mission with international participation. It will be based on one of the two instruments aboard ASTENA: a Laue lens with 20 m focal length, able to focus hard X-rays in the 50-700 keV passband into a 3-d position sensitive focal plane spectrometer. The combination of the focussing properties of the lens and of the localization properties of the detector will provide unparalleled imaging and spectroscopic capabilities, thus enabling studies of phenomena such as gamma-ray bursts afterglows, supernova explosions, positron annihilation lines and many more.

The purpose of this paper is to re-open from a practical perspective the question of the extent in altitude of the Earth's biosphere. We make a number of different suggestions for how searches for biological material could be conducted in the mesosphere and lower thermosphere, colloquially referred to as the ignoreosphere due to its lack of investigation in the meteorological community compared to other regions. Relatively recent technological advances such as CubeSats in Very Low Earth Orbit or more standard approaches such as the rocket borne MAGIC meteoric smoke particle sampler, are shown as potentially viable for sampling biological material in the ignoreosphere. The issue of contamination is discussed and a potential solution to the problem is proposed by the means of a new detector design which filters for particles based on their size and relative-velocity to the detector.

In astronomy, there is an opportunity to enhance the practice of validating models through statistical techniques, specifically to account for measurement error uncertainties. While models are commonly used to describe observations, there are instances where there is a lack of agreement between the two. This can occur when models are derived from incomplete theories, when a better-fitting model is not available or when measurement uncertainties are not correctly considered. However, with the application of specific tests that assess the consistency between observations and astrophysical models in a model-independent way, it is possible to address this issue. The consistency tests (ConTESTs) developed in this paper use a combination of non-parametric methods and distance measures to obtain a test statistic that evaluates the closeness of the astrophysical model to the observations. To draw conclusions on the consistency hypothesis, a simulation-based methodology is performed. In particular, we built two tests for density models and two for regression models to be used depending on the case at hand and the power of the test needed. We used ConTEST to examine synthetic examples in order to determine the effectiveness of the tests and provide guidance on using them while building a model. We also applied ConTEST to various astronomy cases, identifying which models were consistent and, if not, identifying the probable causes of rejection.

We measure the black hole mass and investigate the accretion flow around the local ($z=0.0502$) quasar PG 1119+120. Spectroscopic monitoring with Calar Alto provides H$\beta$ lags and linewidths from which we estimate a black hole mass of $\log \left(M_{\bullet}/\mathrm{M}_{\odot} \right) = 7.0$, uncertain by $\sim0.4$ dex. High cadence photometric monitoring over two years with the Las Cumbres Observatory provides lightcurves in 7 optical bands suitable for intensive continuum reverberation mapping. We identify variability on two timescales. Slower variations on a 100-day timescale exhibit excess flux and increased lag in the $u'$ band and are thus attributable to diffuse bound-free continuum emission from the broad line region. Faster variations that we attribute to accretion disc reprocessing lack a $u'$-band excess and have flux and delay spectra consistent with either $\tau \propto \lambda^{4/3}$, as expected for a temperature structure of $T(R) \propto R^{-3/4}$ for a thin accretion disc, or $\tau \propto \lambda^{2}$ expected for a slim disc. Decomposing the flux into variable (disc) and constant (host galaxy) components, we find the disc SED to be flatter than expected with $f_{\nu} \sim \rm{const}$. Modelling the SED predicts an Eddington ratio of $\lambda_{\rm Edd} > 1$, where the flat spectrum can be reproduced by a slim disc with little dust extinction or a thin disc which requires more dust extinction. While this accretion is super-Eddington, the geometry is still unclear, however a slim disc is expected due to the high radiation pressure at these accretion rates, and is entirely consistent with our observations.

This work focuses on the pilot run of a simulation campaign aimed at investigating the spectroscopic capabilities of the Euclid Near-Infrared Spectrometer and Photometer (NISP), in terms of continuum and emission line detection in the context of galaxy evolutionary studies. To this purpose we constructed, emulated, and analysed the spectra of 4992 star-forming galaxies at 0.3 <= z <= 2 using the NISP pixel-level simulator. We built the spectral library starting from public multi-wavelength galaxy catalogues, with value-added information on spectral energy distribution (SED) fitting results, and from Bruzual and Charlot (2003) stellar population templates. Rest-frame optical and near-IR nebular emission lines were included using empirical and theoretical relations. We inferred the 3.5 sigma NISP red grism spectroscopic detection limit of the continuum measured in the H band for star-forming galaxies with a median disk half-light radius of 0.4 arcsecond at magnitude H = 19.5 +/- 0.2 AB mag for the EuclidWide Survey and at H = 20.8 +/- 0.6 AB mag for the Euclid Deep Survey. We found a very good agreement with the red grism emission line detection limit requirement for the Wide and Deep surveys. We characterised the effect of the galaxy shape on the detection capability of the red grism and highlighted the degradation of the quality of the extracted spectra as the disk size increases. In particular, we found that the extracted emission line signal to noise ratio (SNR) drops by approx. 45% when the disk size ranges from 0.25 to 1 arcsecond. These trends lead to a correlation between the emission line SNR and the stellar mass of the galaxy and we demonstrate the effect in a stacking analysis that can unveil emission lines otherwise too faint to detect.

Using two years of data from the TESS space telescope, we have investigated the time series of 633 overtone pulsating field RR Lyrae (RRc) stars. The majority of stars (82.8 per cent) contain additional frequencies beyond the main pulsation. In addition to the frequencies previously explained by the $\ell = 8$ and $\ell = 9$ non-radial modes, we have identified a group of stars where the additional frequencies may belong to the $\ell = 10$ non-radial modes. We found that stars with no additional frequencies are more common among stars with shorter periods, while stars with longer periods almost always show additional frequencies. The incidence rate and this period distribution both agree well with the predictions of recent theoretical models. The amplitude and phase of additional frequencies are varying in time. The frequencies of different non-radial modes appearing in a given star seem to vary on different timescales. We have determined a 10.4 per cent incidence rate for the Blazhko effect. For several stars we have detected continuous annual-scale phase change without significant amplitude variation. This type of variation offers a plausible explanation for the `phase jump' phenomenon reported in many RRc stars. The main pulsation frequency could show quasi-periodic phase and amplitude fluctuations. This fluctuation is clearly related to additional frequencies present in the star: stars with two non-radial modes show the strongest fluctuations, while stars with no such modes show no fluctuations at all. The summation of the phase fluctuation over time may explain the O-C variations that have long been known for many non-Blazhko RRc stars.

The most widely accepted model of the solar cycle is the flux transport dynamo model. This model evolved out of the traditional $\alpha \Omega$ dynamo model which was first developed at a time when the existence of the Sun's meridional circulation was not known. In these models, the toroidal magnetic field (which gives rise to sunspots) is generated by the stretching of the poloidal field by solar differential rotation. The primary source of the poloidal field in the flux transport models is attributed to the Babcock--Leighton mechanism, in contrast to the mean-field $\alpha$-effect used in earlier models. With the realization that the Sun has a meridional circulation, which is poleward at the surface and is expected to be equatorward at the bottom of the convection zone, its importance for transporting the magnetic fields in the dynamo process was recognized. Much of our understanding about the physics of both the meridional circulation and the flux transport dynamo has come from the mean field theory obtained by averaging the equations of MHD over turbulent fluctuations. The mean field theory of meridional circulation makes clear how it arises out of an interplay between the centrifugal and thermal wind terms. We provide a broad review of mean field theories for solar magnetic fields and flows, the flux transport dynamo modeling paradigm and highlight some of their applications to solar and stellar magnetic cycles. We also discuss how the dynamo-generated magnetic field acts on the meridional circulation of the Sun and how the fluctuations in the meridional circulation, in turn, affect the solar dynamo. We conclude with some remarks on how the synergy of mean field theories, flux transport dynamo models, and direct numerical simulations can inspire the future of this field.

Introduction: The search for life on distant exoplanets is expected to rely on atmospheric biosignatures detection, such as oxygen of biological origin. However, it is not demonstrated how much oxygenic photosynthesis, which on Earth depends on visible light, could work under spectral conditions simulating exoplanets orbiting the Habitable Zone of M-dwarf stars, which have low light emission in the visible and high light emission in the far-red/near-infrared. By utilizing cyanobacteria, the first organisms to evolve oxygenic photosynthesis on our planet, and a starlight simulator capable of accurately reproducing the emission spectrum of an M-dwarf in the range 350-900 nm, we could answer this question. Methods: We performed experiments with the cyanobacterium Chlorogloeopsis fritschii PCC6912, capable of Far-Red Light Photoacclimation (FaRLiP), which allows the strain to harvest far-red in addition to visible light for photosynthesis, and Synechocystis sp. PCC6803, a species unable to perform this photoacclimation, comparing their responses when exposed to three simulated light spectra: M-dwarf, solar and far-red. We analysed growth and photosynthetic acclimation features in terms of pigment composition and photosystems organization. Finally, we determined the oxygen production of the strains directly exposed to the different spectra. Results: Both cyanobacteria were shown to grow and photosynthesize similarly under M-dwarf and solar light conditions: Synechocystis sp. by utilizing the few photons in the visible, C. fritschii by harvesting both visible and far-red light, activating the FaRLiP response.

The identification of the main sulfur reservoir on its way from the diffuse interstellar medium to the cold dense star-forming cores and eventually to protostars is a long-standing problem. Despite sulfur's astrochemical relevance, the abundance of S-bearing molecules in dense cores and regions around protostars is still insufficiently constrained. The goal of this investigation is to derive the gas-phase H$_2$S/OCS ratio for several low-mass protostars, which could provide crucial information about the physical and chemical conditions in the birth cloud of Sun-like stars. Using ALMA ACA Band 6 observations, H$_2$S, OCS, and their isotopologs are searched for in 10 Class 0/I protostars with different source properties such as age, mass, and environmental conditions. An LTE model is used to fit synthetic spectra to the detected lines and to derive the column densities based solely on optically thin lines. The H$_2$S and OCS column densities span four orders of magnitude across the sample. The H$_2$S/OCS ratio is found to be in the range from 0.2 to above 9.7. IRAS 16293-2422 A and Ser-SMM3 have the lowest ratio, while BHR71-IRS1 has the highest. Only the H$_2$S/OCS ratio of BHR71-IRS1 agress within uncertainties with the ratio in comet 67P/C$-$G. The determined gas-phase H$_2$S/OCS ratios can be below the upper limits on the solid-state ratios by as much as an order of magnitude. The H$_2$S/OCS ratio depends significantly on the environment of the birth cloud, such as UV-irradiation and heating received prior to the formation of a protostar. The highly isolated birth environment of BHR71-IRS1 is hypothesized to be the reason for its high gaseous H$_2$S/OCS ratio due to lower rates of photoreactions and more efficient hydrogenation reactions under such dark, cold conditions. The gaseous inventory of S-bearing molecules in BHR71-IRS1 appears to be most similar to that of interstellar ices.

Harmonics are quite common in pulsating stars, and they are always considered to mimic the behaviors of their independent parent pulsation modes and not taken as the key information for asteroseismology. Here, we report an SX Phoenicis star XX Cygni, whose periodogram is dominated by the fundamental frequency $f_{0} = 7.41481 \pm 0.00004\ \mathrm{c\ d}^{-1}$ and its 19 harmonics. According to the analysis of the archival data from TESS, we find that both the amplitudes and frequencies of the fundamental mode and the harmonics vary within TESS Sectors 14-17 and 54-57, which might be caused by the contamination by neighbouring stars. What is more interesting is that, the harmonics show significantly uncorrelated amplitude and frequency variations over time. Some possible origins and interesting issues are proposed to scheme the further research of this hidden corner in current asteroseismology.

The chemical inventory of hot Jupiter (HJ) exoplanets atmospheres continue to be observed by various ground and space based instruments in increasing detail and precision. It is expected that some HJs will exhibit strong non-equilibrium chemistry characteristics in their atmospheres, which might be inferred from spectral observations. We aim to model the three dimensional thermochemical non-equilibrium chemistry in the atmospheres of the HJs WASP-39b and HD 189733b. We couple a lightweight, reduced chemical network `mini-chem' that utilises net reaction rate tables to the Exo-FMS General Circulation Model (GCM). We perform GCM models of the exoplanets WASP-39b and HD 189733b as case studies of the coupled mini-chem scheme. The GCM results are then post-processed using the 3D radiative-transfer model gCMCRT to produce transmission and emission spectra to assess the impact of non-equilibrium chemistry on their observable properties. Both simulations show significant departures from chemical equilibrium (CE) due to the dynamical motions of the atmosphere. The spacial distribution of species generally follows closely the dynamical features of the atmosphere rather than the temperature field. Each molecular species exhibits a different quench level in the simulations, also dependent on the latitude of the planet. Major differences are seen in the transmission and emission spectral features between the CE and kinetic models. Our simulations indicate that considering the 3D kinetic chemical structures of HJ atmospheres has an important impact on physical interpretation of observational data. Drawing bulk atmospheric parameters from fitting feature strengths may lead to inaccurate interpretation of chemical conditions in the atmosphere of HJs. Our open source mini-chem module is simple to couple with contemporary HJ GCM models without substantially increasing required computational resources.

The atmospheric metallicity greatly influences the composition of exoplanet atmospheres. The effect of metallicity on the thermochemical equilibrium is well studied, though its effect on the disequilibrium abundance is loosely constrained. In this study, we have used the quenching approximation to study the effect of metallicity on the quenched abundance for a range of parameters (temperature: 500-2500 K, pressure: 10$^{-4}$-10$^3$ bar, metallicity: 0.1-1000 $\times$ solar metallicity). We determine the chemical timescale by finding rate limiting steps in a reduced chemical network with a network analysis tool and the thermochemical equilibrium abundance. The equilibrium abundance results are similar to the literature. The CO, H$_2$O, and CO$_2$ abundances increase with metallicity in the parameter range considered. The CH$_4$ abundance increases with metallicity for CO/CH$_4$ $<$ 1 and is unaffected for CO/CH$_4$ $>$ 1. The chemical timescale of CO shows minimal change with the metallicity, while the CH$_4$ chemical timescale is inversely proportional to atmospheric metallicity. The quench level of CO shifts into the high-pressure region, and the quench level of CH$_4$ shows complex behavior with metallicity. We benchmarked the quenching approximation with the 1D photochemistry-transport model for two test exoplanets (GJ 1214 b and HD 189733 b) and found it to be in good agreement. We also found that the quenching approximation is a powerful tool to constrain atmospheric parameters. We demonstrated this by constraining the metallicity and transport strength for the test exoplanets HR 8799 b, HD 189733 b, GJ 436 b, and WASP-39 b.

We conducted observations of multiple HC3N (J = 10-9, 12-11, and 16-15) lines and the N2H+ (J = 1-0) line toward a large sample of 61 ultracompact (UC) H II regions, through the Institutde Radioastronomie Millmetrique 30 m and the Arizona Radio Observatory 12 m telescopes. The N2H+ J = 1-0 line is detected in 60 sources and HC3N is detected in 59 sources, including 40 sources with three lines, 9 sources with two lines, and 10 sources with one line. Using the rotational diagram, the rotational temperature and column density of HC3N were estimated toward sources with at least two HC3N lines. For 10 sources with only one HC3N line, their parameters were estimated, taking one average value of Trot. For N2H+, we estimated the optical depth of the N2H+ J = 1-0 line, based on the line intensity ratio of its hyperfine structure lines. Then the excitation temperature and column density were calculated. When combining our results in UC H II regions and previous observation results on high-mass starless cores and high-mass protostellar cores, the N(HC3N)/N(N2H+) ratio clearly increases from the region stage. This means that the abundance ratio changes with the evolution of high-mass star-forming regions (HMSFRs). Moreover, positive correlations between the ratio and other evolutionary indicators (dust temperature, bolometric luminosity, and luminosity-to-mass ratio) are found. Thus we propose the ratio of N(HC3N)/N(N2H+) as a reliable chemical clock of HMSFRs.

The Milky Way accreted several smaller satellite galaxies in its history. These mergers added stars and gas to the Galaxy and affected the properties of the pre-existing stellar populations. Stellar chemical abundances and ages are needed to establish the chronological order of events that occur before, during, and after such mergers. We report precise ages ($\sim$6.5%) and chemical abundances for the Titans, a sample of old metal-poor dwarfs and subgiants with accurate atmospheric parameters. We also obtain ages with an average precision of 10% for a selected sample of dwarf stars from the GALAH survey. We used these stars, located within $\sim$1 kiloparsec of the Sun, to analyse the chronology of the chemical evolution of in-situ and accreted metal-poor stellar populations. We determined ages by isochrone fitting. For the Titans, we determined abundances of Mg, Si, Ca, Ti, Ni, Ba, and Eu using spectrum synthesis. The [Mg/Fe] abundances of the GALAH stars were re-scaled to be consistent with the abundances of the Titans. We separated stellar populations by primarily employing chemical abundances and orbits. We find that star formation in the so-called Gaia-Enceladus or Gaia-Sausage galaxy, the last major system to merge with the Milky Way, lasted at least 3 billion years and got truncated 9.6 $\pm$ 0.2 billion years ago. This marks with very high precision the last stage of its merging process. We also identified stars of a heated metal-poor in-situ population with virtually null net rotation, probably disturbed by several of the early Milky Way mergers. We show that this population is more metal rich than Gaia-Enceladus at any time. The sequence of events uncovered in our analysis supports the hypothesis that Gaia-Enceladus truncated the formation of the high-$\alpha$ disc and caused the gas infall that forms the low-$\alpha$ disc, in agreement with theoretical predictions.

Line-of-sight acceleration of a compact binary coalescence (CBC) event would modulate the shape of the gravitational waves (GWs) it produces with respect to the corresponding non-accelerated CBC. Such modulations could be indicative of its astrophysical environment. We investigate the prospects of detecting this acceleration in future observing runs of the LIGO-Virgo-KAGRA network, as well as in next-generation (XG) detectors and the proposed DECIGO. We place the first observational constraints on this acceleration, for putative binary neutron star mergers GW170817 and GW190425. We find no evidence of line-of-sight acceleration in these events at $90\%$ confidence. Prospective constraints for the fifth observing run of the LIGO at A+ sensitivity, suggest that accelerations for typical BNSs could be constrained with a precision of $a/c \sim 10^{-7}~[\mathrm{s}^{-1}]$, assuming a signal-to-noise ratio of $10$. These improve to $a/c \sim 10^{-9}~[\mathrm{s}^{-1}]$ in XG detectors, and $a/c \sim 10^{-16}~[\mathrm{s}^{-1}]$ in DECIGO. We also interpret these constraints in the context of mergers around supermassive black holes.

Line locking (LL) of absorption line systems is a clear signature of the dynamical importance of radiation pressure force in driving astrophysical flows, with recent findings suggesting that it may be common in quasars exhibiting multiple intrinsic narrow absorption-line (NAL) systems. In this work we probe the phase space conducive to LL and follow the detailed kinematics of those systems that may lock at the velocity separation of the CIV $\lambda\lambda 1548.19,1550.77$ doublet. We find that a small volume of the phase-phase admits LL, suggesting a high-degree of fine-tuning between the physical properties of locked systems. The stability of LL against quasar luminosity variations is quantified with implications for the long-term variability amplitude of quasars and the velocity-separation statistic between multiple NAL systems. The high occurrence of LL by the CIV doublet implies that the hidden extreme-UV emission from quasars is unlikely to be significantly under-estimated by current models. Further, the ratio of the LL velocity to the outflow velocity may serve as a powerful constraint on the composition of the accelerating medium. We conclude that LL poses significant challenges to current theories for the formation of non-intervening NAL systems, and speculate that it may be a manifestation of expanding circumstellar shells around asymptotic giant branch (AGB) stars in the quasar-host bulge.

Observations show that FRBs are highly polarized. Most have high linear polarization degree but a small fraction shows significant circular polarization. We systematically investigate a variety of polarization mechanisms of FRBs within the magnetar theoretical framework considering two possible emission sites, i.e. inside and outside the magnetosphere. For each site, we discuss both intrinsic radiation mechanisms and propagation effects. Inside the magnetosphere, we investigate the polarization properties of both coherent curvature radiation and inverse Compton scattering by charged bunches. In order to have the majority of bursts not having high circular polarization, the bunches should have a large cross section involving a bunch of field lines. Resonant cyclotron absorption within magnetosphere can produce high circular polarization if the resonant condition is satisfied below light cylinder and if electrons and positrons have asymmetric Lorentz factor distribution. Outside the magnetosphere, we consider the synchrotron maser intrinsic emission mechanism and find that the on-beam emission is highly linear polarized. Circular polarization would show up at off-beam angles but the flux is greatly degraded and such bursts are not detectable at cosmological distances. For propagation effects, we consider synchrotron absorption, which tends to reduce circular polarization degree; cyclotron absorption, which tends to generate significant circular polarization; and Faraday conversion, which can convert one polarization mode to another. We discuss astronomical scenarios to allow these processes to happen and conclude that the first two absorption processes require stringent physical conditions. Faraday conversion requires field reversal, which may realize in binary systems or when the FRB engine is surrounded by a supernova remnant.(abridged)

ASASSN-15cm had been identified as a dwarf nova with an orbital period of 5.0 hours and a hot, luminous secondary of of a spectral type around K2.5 in the previous study. Using the Zwicky Transient Facility (ZTF) data, the Asteroid Terrestrial-impact Last Alert System (ATLAS) forced photometry and the All-Sky Automated Survey for Supernovae (ASAS-SN) Sky Patrol data, I found that this object underwent a superoutburst in 2019. I obtained a refined orbital period of 0.2084652(3) d and a superhump period of 0.2196(1) d, which gave a mass ratio q=0.22. Modeling of quiescent ellipsoidal variations yielded an inclination of i=55 deg, consistent with the lack of eclipses during outbursts. The object adds another example of SU UMa stars above or in the period gap containing a secondary with an evolved core, and has the longest orbital period among the established ones. ASASSN-15cm showed relatively regular superoutbursts with a supercycle of 849(18) d between 2015 and 2022, and the next superoutburst is expected to occur in the early half of 2024. Coordinated detailed observations during the next superoutburst are expected to better clarify the nature of this object.

Early optical observations of gamma-ray bursts can significantly contribute to the study of the central engine and physical processes therein. However, of the thousands observed so far, still only a few have data at optical wavelengths in the first minutes after the onset of the prompt emission. Here we report on GRB\,190106A, whose afterglow was observed in optical bands just 36 s after the {\em Swift}/BAT trigger, i.e., during the prompt emission phase. The early optical afterglow exhibits a bimodal structure followed by a normal decay, with a faster decay after $\sim \rm T_{0}+$1 day. We present optical photometric and spectroscopic observations of GRB\,190106A. We derive the redshift via metal absorption lines from Xinglong 2.16-m/BFOSC spectroscopic observations. From the BFOSC spectrum, we measure $z= 1.861\pm0.002$. The double-peak optical light curve is a significant feature predicted by the reverse-forward external shock model. The shallow decay followed by a normal decay in both the X-ray and optical light curves is well explained with the standard forward-shock model with late-time energy injection. Therefore, GRB\,190106A offers a case study for GRBs emission from both reverse and forward shocks.

The Friedmann-Lema\^{i}tre-Robertson-Walker model establishes the correlation between redshifts and distances. It has a metric expansion of space. As a result, the wavelength of photons propagating through the expanding space is stretched, creating the cosmological redshift, $z$. It also relates the frequency of light detected by a local observer to that emitted from a distant source. In standard cosmology (\textit{i.e.} a constant speed light model, $c =$ constant), this relation is given by a factor $1/(1+z)$ [1]. However, this ratio is modified in the minimally extended varying speed of light model (meVSL, $c = c_0 a^{b/4}$) as $1/(1+z)^{1-b/4}$ [2-4]. This time dilation effect can be observed as the observed rate of time variation in the intensity of emitted radiation. The spectra of type Ia supernovae (SNe Ia) provide a reliable way to measure the apparent aging rate of distant objects. We use data on 13 high-redshift ($0.28 \leq z \leq 0.62$) SNe Ia [5] to obtain $b = 0.198 \pm 0.415$ at the $1$-$\sigma$ confidence interval. The current data is consistent with the standard model expectation.

We present the discovery of an apparently non-repeating Fast Radio Burst (FRB) with the MeerKAT radio interferometer in South Africa, as part of the MeerTRAP commensal project. FRB 20210410D with a dispersion measure DM = 578.78 +/- 2 pc/cc was detected in the incoherent beam of ~1.3 deg2 but was bright enough to be localised to sub-arcsec precision in the 2s images made from standard correlation data products. The localisation enabled the association of the FRB with an optical galaxy at z = 0.1415, which is inconsistent with what is expected from the Macquart scaling relation. We attribute the excess DM to the host galaxy. This is the first FRB that is not associated with a dwarf galaxy, to exhibit an excess DM. We do not detect any continuum radio emission at the FRB position or from the host galaxy down to a 3sigma RMS of 14.4 uJy/beam. The FRB is wide with a scattering time of 43.7 +/- 4.3 ms at 1 GHz, and exhibits bifurcation in the spectrum, both of which are reminiscent of repeating FRBs. Although this FRB has not been seen to repeat in 7.28 h at 1.3 GHz with MeerKAT, 3 h at 2.4 GHz with Murriyang and 5.7 h at simultaneous 2.3 GHz and 8.4 GHz observations with the Deep Space Network, we encourage further follow-up to establish a possible repeating nature.

Recent data from the James Webb Space Telescope suggest that there are realistic prospects for detecting the earliest generation of stars at redshift ~20. These metal-poor, gaseous Population III stars are likely in the mass range $10-10^3 M_\odot$. We develop a framework for calculating the abundances of Pop III stars as well as the distribution of the most massive Pop III stars based on an application of extreme-value statistics. Our calculations use the star formation rate density from a recent simulation to calibrate the star-formation efficiency from which the Pop III stellar abundances are derived. Our extreme-value modelling suggests that the most massive Pop III stars at redshifts 10<z<20 are likely to be of order $10^3-10^4 M_\odot$. Extreme Pop III stars were sufficiently numerous to be the seeds of supermassive black holes at high redshifts and possibly source detectable gravitational waves.

In this paper, the modified gravity, which is characterized by the modified factor $\mu$ in the linear matter density perturbation theory, is reconstructed in a completely data-driven and model-independent way via Gaussian process by using currently available cosmic observations, which consist Pantheon+ SNe Ia samples, observed Hubble parameter $H(z)$ and the redshift space distortion $f\sigma_8(z)$ data points. The reconstructed results suggest a time varying $\mu$ at low redshifts. It also implies more complicated modified gravity beyond the simplest general relativity and the Dvali-Gabadadze-Porrati braneworld model is required.

CW Mon is a relatively bright and nearby SS Cyg-type dwarf nova frequently used in detailed analysis of cataclysmic variables and statistical studies. Using Transiting Exoplanet Survey Satellite (TESS) observations, we found that the orbital period is different from what has been adopted. Using the combined data (TESS, the Zwicky Transient Facility data and VSNET campaigns), we updated the period to be 0.19346802(4) d. The previously adopted period of 0.1766 d turned out to be its 2-day alias, probably introduced by a confusion between the two maxima/minima of the ellipsoidal variations. We confirmed that the object showed grazing eclipses during the 2016 and 2002 outbursts, and also in quiescence before and after the 2016 outburst. These eclipses were not necessarily always present and were not remarkable during some past outbursts and in the TESS data. The presence/absence of eclipses may be related to the disk radius or the brightness of the outer part of the disk. A 37-min quasi-period oscillation (QPO) signal was reported during the 2002 outburst. Combined with a recent report of the detection of QPOs around the peaks of long outbursts of a dwarf nova, we suspect that such QPOs during long outbursts may have been excited when the accretion disk reaches the maximum radius, the tidal truncation radius as being a possibility.

We present the first sub-arcsecond localised Fast Radio Burst (FRB) detected using MeerKAT. The FRB, FRB 20210405I, was detected in the incoherent beam using the MeerTRAP pipeline on 2021 April 05 with a signal to noise ratio of 140.8 and a dispersion measure of 565.17 pc cm$^{-3}$. It was detected while MeerTRAP was observing commensally with the ThunderKAT large survey project, and was sufficiently bright that we could use the ThunderKAT 8s images to localise the FRB. Two different models of the dispersion measure in the Milky Way and halo suggest that the source is either right at the edge of the Galaxy, or outside. However, we use the combined localisation, dispersion measure, scattering, specific luminosity and chance coincidence probability information to find that the origin is most likely extragalactic and identify the likely host galaxy of the FRB: 2MASS J1701249$-$4932475. Using SALT spectroscopy and archival observations of the field, we find that the host is a disk/spiral galaxy at a redshift of $z=0.066$.

Multi-element interferometers such as MeerKAT, which observe with high time resolution and have a wide field-of-view, provide an ideal opportunity to perform real-time, untargeted transient and pulsar searches. However, because of data storage limitations, it is not always feasible to store the baseband data required to image the field of a discovered transient or pulsar. This limits the ability of surveys to effectively localise their discoveries and may restrict opportunities for follow-up science, especially of one-off events like some Fast Radio Bursts (FRBs). Here we present a novel maximum-likelihood estimation approach to localising transients and pulsars detected in multiple MeerKAT tied-array beams at once, which we call Tied Array Beam Localisation (TABLo), as well as a Python implementation of the method named SeeKAT. We provide real-world examples of SeeKAT's use as well as a Monte Carlo analysis to show that it is capable of localising single pulses detected in beamformed MeerKAT data to (sub-)arcsecond precision.

We present a detailed study of NGC 6791, NGC 6811, NGC 6819 and NGC 6866, the four open clusters that are located in the Kepler prime field. We use new CCD UBV(RI)KC photometry, which was combined with Gaia EDR3 photometric/astrometric data, to derive the astrophysical parameters with two independent methods - one of them the fitCMD algorithm. Furthermore, we provide among others estimates of the mass and mass function, the cluster structure, derive the cluster orbits, and discuss the cluster dynamics. All objects belong to the older open cluster population (1-7Gyr), are in an advanced dynamical stage with signs of mass segregation, and are located close to the solar circle, but show a large range in respect of radii, member stars or observed cluster mass (100-2000 Msolar). For the three younger objects we were also able to provide photometric metallicity estimates, which confirms their status as clusters with a roughly solar metallicity. The most outstanding object is clearly NGC 6791, a very old cluster with a high metallicity at a distance of about 4.5 kpc from the Sun. We estimate a probable radial migration by about 7 kpc, resulting in a birth position close to the Galactic center.

We perform multi-dimensional core-collapse supernova (CCSN) simulations in a massive scalar-tensor theory for the first time with a realistic equation of state and multi-energy neutrino radiation. Among the set of our models varying the scalar mass and the coupling strength between the scalar and gravitational fields, a particular model allows for recurrent spontaneous scalarizations (SSs) in the proto-neutron star (PNS). Each SS induces the PNS collapse and subsequent bounce, from which devastating shock waves emanate and eject the PNS envelope. The explosion energy can easily exceed $\mathcal O(10^{51})$ erg. This study reveals new aspects of SS as the explosion mechanism of CCSNe. We also discuss its characteristic multi-messenger signals: neutrinos and gravitational waves.

Type Ia supernovae (SNe Ia) are successful cosmological distance indicators and important element factories in the chemical evolution of galaxies. They are generally thought to originate from thermonuclear explosions of carbon-oxygen white dwarfs in close binaries. However, the observed diversity among SNe Ia implies that they have different progenitor models. In this article, we performed the long-term evolution of NS+He star binaries with different initial He star masses ($M_{\rm He}^{\rm i}$) and orbital periods ($P_{\rm orb}^{\rm i}$) for the first time, in which the He star companions can explode as SNe Ia eventually. Our simulations indicate that after the He stars develop highly degenerate oxygen-neon (ONe) cores with masses near the Chandrasekhar limit, explosive oxygen burning can be triggered due to the ignition of central residual carbon. According to these calculations, we obtained an initial parameter space for the production of SNe Ia in the $\rm log\,$$P^{\rm i}_{\rm orb}-M^{\rm i}_{\rm He}$ plane. Meanwhile, we found that isolated mildly recycled pulsars can be formed after He stars explode as SNe Ia in NS+He star binaries, in which the isolated pulsars have minimum spin periods ($P_{\rm spin}^{\rm min}$) of $\sim 30-110\rm\,ms$ and final orbital velocities of $\sim \rm 60-360\,km\,s^{-1}$, corresponding to initial orbital periods of $0.07-10\rm\,d$. Our work suggests that the NS+He star channel may contribute to the formation of isolated mildly recycled pulsars with velocity $\rm \lesssim 360\,km\,s^{-1}$ in observations, and such isolated pulsars should locate in the region of pulsars with massive WD companions in the $P_{\rm spin}-\dot P_{\rm spin}$ diagram.

Neutron stars are commonly modelled as a spherical, rotating perfect conductors with a predominant intrinsic dipolar magnetic field anchored to their stellar crust. If compact enough, General Relativity modifies Maxwell's equations, leading to changes in the interior and exterior electromagnetic solutions. We present analytic solutions for a slowly-rotating magnetized neutron star that include the frame-dragging correction to the magnetic field components. For typical compactness values, i.e. $R_s \sim 0.5 [R_*]$, we show that the new terms account for a $0.43\%$ decrease in magnetic field strength at the equator and an average $1\%$ vectorial angle correction, both compared to the case without the magnetic frame-dragging correction. This correction leads to a self-consistent redistribution of the surface azimuthal current. We tested the validity of the derived solution by prescribing it as an initial value problem to two-dimensional particle-in-cell simulations. We observe a lower early-stage transient amplitude which reflects the proximity between the derived and exact solutions. At later times, our solution reduces the azimuthal electric field amplitude by almost an order of magnitude, demonstrating that simulations are more accurate at the expense of a more involved initialization. We show that this can potentially lead to a reduction of simulation runtimes.

The MERTIS (MErcury Radiometer and Thermal Infrared Spectrometer) instrument onboard the ESA/JAXA BepiColombo mission will provide mid-infrared data, which will be crucial to characterize the surface mineralogy of Mercury. In order to interpret the results, we are creating a database of mid infrared spectra. As part of a study of synthetic glasses which are to serve as analog materials for the interpretation of remote sensing and modeling data, we present mid infrared data for analog materials of Mercury regolith, surface and mantle compositions. In addition, we provide data for similar analogs of Earth, Moon, Venus, and Mars rocks for a coherent picture. The analog samples have been first characterized by optical microscopy, Raman spectroscopy and EMPA. Powdered size fractions (0-25 micron, 25-63 micron, 63-125 micron, and 125 -250 micron) were studied in reflectance in the mid-infrared range from 2.5 to 18 micron (550 to 2000cm-1), additional micro FTIR analyses were also obtained. Results for the size fractions of the surface and regolith analogs for Mercury show typical features for amorphous material with Christiansen Features (CF) at 8 to 8.1 micron, Reststrahlen Bands (RB) at 9.8 to 9.9 micron, and the Transparency Feature (TF) at 12 micron. The six bulk silicate Mercury analogs have varying CF positions from 8.1 to 9 micron, with RB crystalline features of various olivines dominating in most samples. Similarly, bulk silicate analogs of the other planetary bodies show glassy features for the surface analogs with CF from 7.9 micron (Earth Continental Crust) to 8.3 micron (Lunar Mare), strong RB from 9.5 micron (Earth Continental Crust ) to 10.6 micron (Lunar Mare and Highlands). TF are usually very weak for the glassy analogs.

We explore the properties of galaxies in the proximity (within a $\sim$2 Mpc radius sphere) of Type I quasars at 0.1<z<0.35, to check whether and how an active galaxy influences the properties of its neighbors. We further compare these with the properties of neighbors around inactive galaxies of the same mass and redshift within the same volume of space, using the Galaxy and Mass Assembly (GAMA) spectroscopic survey. Our observations reveal no significant difference in properties such as the number of neighbors, morphologies, stellar mass, star formation rates, and star formation history between the neighbors of quasars and those of the comparison sample. This implies that quasar activity in a host galaxy does not significantly affect its neighbors (e.g. via interactions with the jets). Our results suggest that quasar host galaxies do not strongly differ from the average galaxy within the specified mass and redshift range. Additionally, the implication of the relatively minor importance of the environmental effect on and from quasars is that nuclear activity is more likely triggered by internal and secular processes.

Celestial sources emitting at high-energy (HE, E > 100 MeV) and at very high-energy (VHE, E > 100 GeV) gamma-rays are of the order of a few thousands and a few hundreds, respectively. On the other hand, the number of sources emitting at ultra high-energy (UHE, E > several tens of TeV) gamma-rays are just a few dozens, and are currently being investigated by means of both ground-based imaging atmospheric Cherenkov telescopes (IACTs) and particle shower arrays. These rare VHE and UHE sources represent a new frontier in astrophysics. An array composed of nine ASTRI Cherenkov telescopes is under construction at the Observatorio del Teide (Tenerife, Spain). The ASTRI Mini-Array aims at providing robust answers to a few selected open questions in the VHE and UHE domains. The scientific program during the first four observing years will be devoted to the following Core Science topics: the origin of cosmic rays, the extra-galactic background light and the study of fundamental physics, the novel field in the VHE domain of gamma-ray bursts and multi-messenger transients, and finally the use of the ASTRI Mini-Array to investigate ultra high-energy cosmic rays and to undertake stellar intensity interferometry studies. We review the scientific prospects assessed through dedicated simulations, proving the potential of the ASTRI Mini-Array in pursuing breakthrough discoveries and discuss the synergies with current and future VHE facilities in the Northern hemisphere, such as MAGIC, LHAASO, HAWC, Tibet AS-$\gamma$, and CTAO-N.

We present our analysis of new and archived observations of two candidate magnetic cataclysmic variables, namely 1RXS J174320.1-042953 and YY Sex. 1RXS J174320.1-042953 was observed in two distinctive high and low states where a phase shift was seen, which could be due to the changes in the shape, size, and (or) location of the accretion region. We find that its orbital X-ray modulations only persist in the soft (0.3-2.0 keV) energy band, which could be attributed to the photoelectric absorption in the accretion flow. The X-ray spectra exhibit a multi-temperature post-shock region where the hard X-rays are absorbed through a thick absorber with an equivalent hydrogen column of $\sim$7.5 $\times$ 10$^{23}$ cm$^{-2}$, which partially covers $\sim$56 per cent of the emission. No soft X-ray excess was found to be present; however, a soft X-ray emission with a blackbody temperature of $\sim$97 eV describes the spectra. Extensive TESS observations of YY Sex allow us to refine its orbital period to 1.5746 $\pm$ 0.0011 h. We did not find any signature of previously reported spin or beat periods in this system. Furthermore, our new polarimetric observations show clear circular polarization modulated on the orbital period only. Finally, both systems show strong Balmer and He II 4686 A$^\circ$ emission lines in the optical spectra, further indicative of their magnetic nature.

As the earliest relics of star formation episodes in the history of the Universe, the most massive galaxies are the key to our understanding of the evolution of the stellar population, cosmic structure, and SMBHs. However, the details of their formation histories remain uncertain. We address these problems by planning a large survey sample of ultramassive galaxies ($z\le0.3$, $|\delta+24^{\circ}|<45$\deg, $|b|>8$\deg), including 76\% E, 17\% S0, and 7\% S brighter than $M_K\le-27$ mag (stellar mass $2\times10^{12}<M_\star<5\times10^{12}$ M$_\odot$) with the HARMONI instrument on ELT. We thus describe our most massive galaxies survey, discuss the distinct demographics and environmental properties of the selected galaxies, and simulate their HARMONI $I_z$, $I_z+J$, and $H+K$-band IFS observations via combining the inferred stellar-mass models from the images of Pan-STARRS observations, a synthetic spectrum of the assumed stellar population, and an SMBH with a specific mass estimated based on different black hole scaling relations. We find HARMONI can produce excellent state-of-art IFS datacubes even for targets beyond the limits of the current suite of 8m class ground-based telescopes with adaptive optic assisted like Gemini and VLT in a relatively short exposure time. We extract the stellar kinematics from the simulated IFU data using the stellar-absorption CaT and some stellar features in ($I_z$, $I_z+J$) and $H+K$ band, respectively; then used them to reconstruct the SMBH mass and its error using MCMC simulation. The simulated stellar kinematics were achieved with a median random noise of $\Delta V_{\rm rms}\lesssim1.5$\%. Thus, our simulations and modelings can be used as benchmarks to evaluate the instrument models and pipelines dedicated to HARMONI, appearing to be promising tools to exploit the unprecedented capabilities of ELT in future works.

The separation of oxygen- and carbon-rich AGB sources is crucial for their accurate use as local and cosmological distance and age/metallicity indicators. We investigate the use of unsupervised learning algorithms for classifying the chemistry of long-period variables from Gaia DR3's BP/RP spectra. Even in the presence of significant interstellar dust, the spectra separate into two groups attributable to O-rich and C-rich sources. Given these classifications, we utilise a supervised approach to separate O-rich and C-rich sources without BP/RP spectra but instead given broadband optical and infrared photometry finding a purity of our C-rich classifications of around $95$ per cent. We test and validate the classifications against other advocated colour-colour separations based on photometry. Furthermore, we demonstrate the potential of BP/RP spectra for finding S-type stars or those possibly symbiotic sources with strong emission lines. Although our classification suggests the Galactic bar-bulge is host to very few C-rich long-period variable stars, we do find a small fraction of C-rich stars with periods $>250\,\mathrm{day}$ that are spatially and kinematically consistent with bar-bulge membership. We argue the combination of the observed number, the spatial alignment, the kinematics and the period distribution disfavour young metal-poor star formation scenarios either in situ or in an accreted host, and instead, these stars are highly likely to be the result of binary evolution and the evolved versions of blue straggler stars already observed in the bar-bulge.

Empirical and theoretical studies have demonstrated that the periods of Mira variable stars are related to their ages. This, together with their brightness in the infrared, makes them powerful probes of the formation and evolution of highly-extincted or distant parts of the Local Group. Here we utilise the Gaia DR3 catalogue of long-period variable candidates to calibrate the period-age relation of the Mira variables. Dynamical models are fitted to the O-rich Mira variable population across the extended solar neighbourhood and then the resulting solar neighbourhood period-kinematic relations are compared to external calibrations of the age-kinematic relations to derive a Mira variable period-age relation of $\tau\approx(6.9\pm0.3)\,\mathrm{Gyr}(1+\tanh((330\,\mathrm{d}-P)/(400\pm90)\mathrm{d})$. Our results compare well with previous calibrations using smaller datasets as well as the period-age properties of Local Group cluster members. This calibration opens the possibility of accurately characterising the star formation and the impact of different evolutionary processes throughout the Local Group.

On 2022 October 9 the brightest gamma-ray burst (GRB) ever observed lit up the high-energy sky. It was detected by a multitude of instruments, attracting the close attention of the GRB community, and saturated many detectors. GRBAlpha, a nano-satellite with a form factor of a 1U CubeSat, has detected this extraordinarily bright long-duration GRB 221009A without strong saturation. We present light curves of the prompt emission in 13 energy bands, from 80 keV to 950 keV, and perform a spectral analysis to calculate the peak flux and peak isotropic-equivalent luminosity. Since the satellite's attitude information is not available for the time of this GRB, more than 200 incident directions were probed in order to find the median luminosity and its systematic uncertainty. We found that the peak flux in the $80-800$ keV range (observer frame) was $F_{\rm{ph}}^{\rm{p}}=1300_{-200}^{+1200}$ ph cm$^{-2}$s$^{-1}$ or $F_{\rm{erg}}^{\rm{p}}=5.7_{-0.7}^{+3.7}\times10^{-4}$ erg cm$^{-2}$s$^{-1}$ and the fluence in the same energy range of the first GRB episide which was observable by GRBAlpha was $S=2.2_{-0.3}^{+1.4}\times10^{-2}$ erg cm$^{-2}$. The peak isotropic-equivalent luminosity in the $92-920$ keV range (rest frame) was $L_{\rm{iso}}^{\rm{p}}=3.7_{-0.5}^{+2.5}\times10^{52}$ erg s$^{-1}$ and the bolometric peak isotropic-equivalent luminosity was $L_{\rm{iso}}^{\rm{p,bol}}=8.4_{-0.9}^{+1.4}\times10^{52}$ erg s$^{-1}$ in the $1-10,000$ keV range (rest frame). The peak emitted energy is $E_p^\ast=E_p(1+z)=1120\pm470$ keV. Our measurement of $L_{\rm{iso}}^{\rm{p,bol}}$ is consistent with the Yonetoku relation.

Aims. Since launched on 2021 March 22, the 1U-sized CubeSat GRBAlpha operates and collects scientific data on high-energy transients, making it the smallest astrophysical space observatory to date. GRBAlpha is an in-obit demonstration of a gamma-ray burst (GRB) detector concept suitably small to fit into a standard 1U volume. As it was demonstrated in a companion paper, GRBAlpha adds significant value to the scientific community with accurate characterization of bright GRBs, including the recent event of GRB 221009A. Methods. The GRB detector is a 75x75x5 mm CsI(Tl) scintillator wrapped in a reflective foil (ESR) read out by an array of SiPM detectors, multi-pixel photon counters by Hamamatsu, driven by two separate, redundant units. To further protect the scintillator block from sunlight and protect the SiPM detectors from particle radiation, we apply a multi-layer structure of Tedlar wrapping, anodized aluminium casing and a lead-alloy shielding on one edge of the assembly. The setup allows observations of gamma radiation within the energy range of 70-890 keV and having an energy resolution of ~30%. Results. Here, we summarize the system design of the GRBAlpha mission, including the electronics and software components of the detector, some aspects of the platform as well as the current way of semi-autonomous operations. In addition, details are given about the raw data products and telemetry in order to encourage the community for expansion of the receiver network for our initiatives with GRBAlpha and related experiments.

Despite the enormous efforts done in very recent years, both theoretically and experimentally, the basic three questions about the cosmic rays origin remain without clear answers: what are their sources, how are they accelerated, how do they propagate? Gamma-ray astronomy plays a fundamental role in this field. Both relativistic protons and electrons can emit in the gamma-ray band through different processes, but only the detection of hadronic gamma-ray emission can probe the acceleration of cosmic rays. In particular, due to the Klein-Nishina suppression of inverse Compton emission at the highest energies, the detection of gamma-ray emission above 100 TeV was expected to provide firm proof of the acceleration of PeV hadrons. However, the recent results published by the LHAASO collaboration revealed the existence of several PeV sources likely related to PWNe, well known leptonic factories (e.g. the Crab Nebula for all). As a consequence, a gamma-ray detection at PeV energies may no longer be the final proof of hadronic acceleration. However, the limited angular resolution of LHAASO makes associations uncertain and more detailed and deeper studies are needed. In this context, the ASTRI Mini-Array, with its unprecedented sensitivity and angular resolution at E>10 TeV, not only can extend the gamma-ray spectra of candidate Cosmic Ray factories but could help to distinguish emission regions from PWNe and other LHAASO sources, shedding light on the nature of the highest energy emission.

Fast Radio Bursts (FRBs) are short astrophysical transients of extragalactic origin. Their burst signal is dispersed by the free electrons in the large-scale-structure (LSS), leading to delayed arrival times at different frequencies. Another potential source of time delay is the well known Shapiro delay, which measures the space-space and time-time metric perturbations along the line-of-sight. If photons of different frequencies follow different trajectories, i.e. if the universality of free fall guaranteed by the weak equivalence principle (WEP) is violated, they would experience an additional relative delay. This quantity, however, is not an observable on the background level as it is not gauge independent, which has led to confusion in previous papers. Instead, an imprint can be seen in the correlation between the time delays of different pulses. In this paper, we derive robust and consistent constraints from twelve localised FRBs on the violation of the WEP in the energy range between 4.6 and 6 meV. In contrast to a number of previous studies, we consider our signal to be not in the model, but in the covariance matrix of the likelihood. To do so, we calculate the covariance of the time delays induced by the free electrons in the LSS, the WEP breaking terms, the Milky Way and host galaxy. By marginalising over both host galaxy contribution and the contribution from the free electrons, we find that the parametrised post-Newtonian parameter $\gamma$ characterising the WEP violation must be constant in this energy range to 1 in $10^{13}$ at 68$\;\%$ confidence. These are the tightest constraints to-date on $\Delta\gamma$ in this low energy range.

A correlation between astrophysical high-energy neutrinos and blazars has been suggested by various authors. In particular, a likely association between IceCube events and intermediate and high-energy peaked BL Lac objects has led to a sample of 47 objects having a high probability of being neutrino sources. In the first paper of this series we reported optical spectroscopy of 17 objects, which together with data taken from the literature covered 80 per cent of the sample. Here we present spectroscopy obtained at large aperture telescopes of a further 17 objects (plus four additional targets), which completes the sample coverage. For twelve objects we are able to determine the redshift (0.07 < z <1.6), while for the others we set a lower limit on it, based on either the robust detection of intervening absorption systems or on an estimation derived from the absence of spectral signatures of the host galaxy. With these new data we expand and reinforce the main results of our previous papers, namely the fact that in terms of their broad-band properties our sources appear to be indistinguishable from the rest of the blazar population and the relatively large (>34 per cent and possibly as high as 80 per cent) fraction of masquerading BL Lac objects, for which the low equivalent width of the emission lines is due to the brightness of the boosted continuum, rather than being an intrinsic property, in our sample.

With a Jupiter-like exoplanet and a debris disk with both asteroid and Kuiper belt analogs, $\epsilon$ Eridani has a fascinating resemblance to our expectations for a young Solar System. We present a deep HST/STIS coronographic dataset using eight orbit visits and the PSF calibrator $\delta$ Eridani. While we were unable to detect the debris disk, we place stringent constraints on the scattered light surface brightness of $\sim 4 \, \mu Jy/arcsec^{2}$. We combine this scattered light detection limit with a reanalysis of archival near and mid-infrared observations and a dynamical model of the full planetary system to refine our model of the $\epsilon$ Eridani debris disk components. Radiative transfer modeling suggests an asteroid belt analog inside of 3 au, an intermediate disk component in the 6 - 37 au region and a Kuiper belt analog co-located with the narrow belt observed in the millimeter (69 au). Modeling also suggests a large minimum grain size requiring either very porous grains or a suppression of small grain production, and a radially stratified particle size distribution. The inner disk regions require a steep power law slope ($s^{-3.8}$ where $s$ is the grain size) weighted towards smaller grains and the outer disk prefers a shallower slope ($s^{-3.4}$) with a minimum particle size of $> 2 \, \mu m$. These conclusions will be enhanced by upcoming coronographic observations of the system with the James Webb Space Telescope, which will pinpoint the radial location of the dust belts and further diagnose the dust particle properties.

The so-called `impossibly early galaxy' problem, first identified via the Hubble Space Telescope's observation of galaxies at redshifts z > 10, appears to have been exacerbated by the more recent James Webb Space Telescope (JWST) discovery of galaxy candidates at even higher redshifts (z ~ 17) which, however, are yet to be confirmed spectroscopically. These candidates would have emerged only ~ 230 million years after the big bang in the context of LCDM, requiring a more rapid star formation in the earliest galaxies than appears to be permitted by simulations adopting the concordance model parameters. This time-compression problem would therefore be inconsistent with the age-redshift relation predicted by LCDM. Instead, the sequence of star formation and galaxy assembly would confirm the timeline predicted by the R_h=ct universe, a theoretically advanced version of LCDM that incorporates the `zero active mass' condition from general relativity. This model has accounted for many cosmological data better than LCDM, and eliminates all of its inconsistencies, including the horizon and initial entropy problems. The latest JWST discoveries at z > 14, if confirmed, would add further support to the idea that the R_h=ct universe is favored by the observations over the current standard model.

We present a sample of well-localised Fast Radio Bursts (FRBs) discovered by the MeerTRAP project at the MeerKAT telescope in South Africa. We discovered the three FRBs in single coherent tied-array beams and localised them to an area of ~1 arcmin$^2$. We investigate their burst properties, scattering, repetition rates, and localisations in a multi-wavelength context. FRB 20201211A shows hints of scatter broadening but is otherwise consistent with instrumental dispersion smearing. For FRB 20210202D, we discovered a faint post-cursor burst separated by ~200 ms, suggesting a distinct burst component or a repeat pulse. We attempt to associate the FRBs with host galaxy candidates. For FRB 20210408H, we tentatively (0.35 - 0.53 probability) identify a compatible host at a redshift ~0.5. Additionally, we analyse the MeerTRAP survey properties, such as the survey coverage, fluence completeness, and their implications for the FRB population. Based on the entire sample of 11 MeerTRAP FRBs discovered by the end of 2021, we estimate the FRB all-sky rates and their scaling with the fluence threshold. The inferred FRB all-sky rates at 1.28 GHz are $4.4_{-2.5}^{+4.3}$ and $2.1_{-1.1}^{+1.8} \times 10^3$ sky$^{-1}$ d$^{-1}$ above 0.66 and 3.44 Jy ms for the coherent and incoherent surveys, respectively. The scaling between the MeerTRAP rates is flatter than at higher fluences at the 95 per cent confidence level. There seems to be a deficit of low-fluence FRBs, suggesting a break or turn-over in the rate versus fluence relation below 2 Jy ms. We speculate on cosmological or progenitor-intrinsic origins. The cumulative source counts within our surveys appear consistent with the Euclidean scaling.

There are various indications that the most primitive small bodies (P, D-type asteroids, comets) have surfaces made of intimate mixtures of opaque minerals and other components (silicates, carbonaceous compounds, etc.) in the form of sub-micrometre-sized grains, smaller than the wavelength at which they are observed, so-called hyperfine grains. Here, we investigate how the Vis-NIR-MIR spectral and V-band polarimetric properties of surfaces made of hyperfine grains are influenced by the relative abundance of such hyperfine materials, having strongly different optical indexes. Mixtures of grains of olivine and iron sulfide (or anthracite), as analogues of silicates and opaque minerals present on small bodies, were prepared at different proportions. The measurements reveal that these mixtures of hyperfine grains have spectral and polarimetric Vis-NIR properties varying in strongly nonlinear ways. When present at even a few percent, opaque components dominate the Vis-NIR spectral and polarimetric properties, and mask the silicate bands at these wavelengths. The Vis-NIR spectral slope ranges from red (positive slope), for pure opaque material, to blue (negative slope) as the proportion of silicates increases, which is reminiscent of the range of spectral slopes observed on P, D, X, C- and B-types asteroids. The spectra of the darkest mixtures in the Vis-NIR exhibit the absorption bands of Si-O in olivine around 10 m in the MIR, which is observed in emission for several small bodies. This work shows that both the contrasted optical indexes of the components, and the dispersion or aggregation (depending on their relative proportions) of their hyperfine grains, induce different light scattering regimes in the Vis-NIR and MIR, as observed for primitive small bodies. The optical separation of hyperfine grains seems to be a major parameter controlling the optical properties of these objects.

Radiation pressure on dust is an important feedback process around star clusters and may eject gas from bright sub-regions in star-forming galaxies. The Eddington ratio has previously been constructed for galaxy-averaged observations, individual star clusters, and Galactic HII regions. Here we assess the role of radiation pressure in thousands of sub-regions across two local star-forming galaxies, NGC 6946 and NGC 5194. Using a model for the spectral energy distribution from stellar population synthesis and realistic dust grain scattering and absorption, we compute flux- and radiation pressure-mean opacities and population-averaged optical depth $\langle\tau_{\rm RP}\rangle$. Using Monte-Carlo calculations, we assess the momentum coupling through a dusty column to the stellar continuum. Optically-thin regions around young stellar populations are $30-50$ times super-Eddington. We calculate the Eddington ratio for the sub-regions including the local mass of young and old stars and HI and molecular gas. We compute the fraction of the total star formation that is currently super-Eddington, and provide an assessment of the role of radiation pressure in the dusty gas dynamics. Depending on the assumed height of the dusty gas and the age of the stellar population, we find that $\sim0-10$% of the sightlines are super-Eddington. These regions may be accelerated to $\sim5-15$ km/s by radiation pressure alone. Additionally, our results show that for beamed radiation the function $1-\exp(-\langle\tau_{\rm RP}\rangle)$ is an excellent approximation to the momentum transfer. Opacities and optical depths are tabulated for SEDs of different stellar ages and for continuous star formation.

Recent observations of GN-z11 with JWST/NIRSpec revealed numerous oxygen, carbon, nitrogen, and helium emission lines at $z=10.6$. Using the measured line fluxes, we derive abundance ratios of individual elements within the interstellar medium (ISM) of this super-luminous galaxy. Driven by the unusually-bright NIII] $\lambda$1750 and NIV] $\lambda$1486 emission lines (and by comparison faint OIII] $\lambda\lambda$1660, 1666 lines), our fiducial model prefers log(N/O)>-0.25, greater than four times solar and in stark contrast to lower-redshift star-forming galaxies. The derived log(C/O)>-0.78, ($\approx$30 % solar) is also elevated with respect to galaxies of similar metallicity (12+log(O/H)$\approx7.82$), although less at odds with lower-redshift measurements. Given the long timescale typically expected to enrich nitrogen with stellar winds, traditional scenarios require a very fine-tuned formation history to reproduce such an elevated N/O. We find no compelling evidence that nitrogen enhancement in GN-z11 can be explained by enrichment from metal-free Population III stars. Interestingly, yields from runaway stellar collisions in a dense stellar cluster or a tidal disruption event provide promising solutions to give rise to these unusual emission lines at $z=10.6$, and explain the resemblance between GN-z11 and a nitrogen-loud quasar. These recent observations showcase the new frontier opened by JWST to constrain galactic enrichment and stellar evolution within 440 Myr of the Big Bang.

We present an analysis of the $BVRI$ photometry of the blazar BL Lacertae on diverse timescales from mid-July to mid-September 2020. We have used 11 different optical telescopes around the world and have collected data over 84 observational nights. The observations cover the onset of a new activity phase of BL Lacertae started in August 2020 (termed as the August 2020 flare by us), and the analysis is focused on the intra-night variability. On short-term timescales, (i) flux varied with $\sim$2.2\,mag in $R$ band, (ii) the spectral index was found to be weakly dependent on the flux, that is the variations could be considered mildly chromatic, and (iii) no periodicity was detected. On intra-night timescales, BL Lacertae was found to show bluer-when-brighter chromatism predominantly. We also found two cases of significant inter-band time lags of the order of a few minutes. The duty cycle of the blazar during the August 2020 flare was estimated to be quite high ($\sim$90\% or higher). We decomposed the intra-night light curves into individual flares and determined their characteristics. On the base of our analysis and assuming the turbulent jet model, we determined some characteristics of the emitting regions: Doppler factor, magnetic field strength, electron Lorentz factor, and radius. The radii determined were discussed in the framework of the Kolmogorov theory of turbulence. We also estimated the weighted mean structure function slope on intra-night timescales, related it to the slope of the power spectral density, and discussed it regarding the origin of intra-night variability.

We study the periapsis shift of a quasi-circular orbit in a general static spherically symmetric spacetime. We derive two formulae in full order with respect to the gravitational field, one in terms of the gravitational mass $m$ and the Einstein tensor and the other in terms of the orbital angular velocity and the Einstein tensor. These formulae reproduce the well-known ones for the prograde shift in the Schwarzschild spacetime. In a general case, the shift deviates from that in the vacuum spacetime due to a particular combination of the components of the Einstein tensor at the radius $r$ of the orbit. The formulae give a retrograde shift due to the extended-mass effect in Newtonian gravity. In general relativity, in the weak-field regime near a massive object, the active gravitational mass density, $\rho_{A}=(\epsilon+p_{r}+2p_{t})/c^{2}$, plays an important role, where $\epsilon$, $p_{r}$, and $p_{t}$ are the energy density, the radial stress, and the tangential stress of the matter field, respectively. We show that a retrograde shift requires $\rho_{A}$ to be beyond a critical value $\rho_{c}\simeq 2.8\times 10^{-15} \mbox{g}/\mbox{cm}^{3} (m/M_{\odot})^{2}(r/\mbox{au})^{-4}$, while a prograde shift greater than that in the vacuum spacetime instead implies $\rho_{A}<0$, i.e., the violation of the strong energy condition, and thereby provides evidence for dark energy. Implications for dark matter in the Solar System and the Galactic Center are also discussed.

We propose possible properties of quantum gravity in de Sitter space, and find that they relate the value of the cosmological constant to parameters of the Standard Model. In de Sitter space we suggest (i) that the most sharply defined observables are obtained by scattering objects from the horizon and back to the horizon and (ii) that black holes of discrete charge are well defined states in the theory. For a black hole of minimal discrete electric charge, we therefore demand that a scattering process involving the black hole and a probe can take place within a Hubble time before evaporating away, so that the state of a discretely charged black hole is well defined. By imposing that the black hole's charge is in principle detectable, which involves appreciably altering the state of a scattered electron, we derive a relation between the Hubble scale, or cosmological constant, and the electron's mass and charge and order one coefficients that describe our ignorance of the full microscopic theory. This gives the prediction $\Lambda \sim 10^{-123 \pm 2} M_{Pl}^4$, which includes the observed value of dark energy. We suggest possible ways to test this proposal.

Exotic spin-dependent interactions mediated by new light particles led to solutions to several important questions in modern physics. Such interactions involving a scalar coupling $g_S^N$ at one vertex and a pseudo-scalar coupling $g_P^n$ at the polarized neutron vertex can be induced by the exchange of spin-0 bosons, or a vector/axial-vector coupling $g_V^N$/$g_A^N$ at one vertex and an axial-vector coupling $g_A^n$ at the polarized neutron vertex can be induced by the exchange of spin-1 bosons. If such new interactions exist, the Sun and the Moon can induce sidereal variations of effective fields along the direction perpendicular to the Earth's rotation axis. We derived new experimental upper limits on such exotic spin-dependent interactions at astronomical interaction ranges by analyzing existing data from laboratory measurements on the Lorentz and CPT violation. We set the most stringent experimental limits on $g_S^Ng_P^n$ ranging from $\sim 2\times 10^{10}$m to $\sim 10^{14}$m. Previously, the best limit on $g_S^Ng_P^n$ at this range is from astrophysics. The result is the first time laboratory limits surpass the astrophysical ones on the scalar-pseudoscalar type interaction, to our best knowledge. We report new constraints on vector-axial-vector and axial-axial-vector type interaction at the range of astronomical scales. The new limits on vector-axial-vector are improved by as much as $\sim$12 orders of magnitude. We also apply the analysis to the Hari-Dass interactions and obtain corresponding new constraints on the interactions. We discuss the possibilities of using the beam method to further search the interaction involving other particles, such as electrons, muons, etc., based on the same idea.

Non-selfgravitating equilibrium tori orbiting around black holes have a long history and have been employed in numerous simulations of accretion flows onto black holes and other compact objects. We have revisited the problem of constructing such equilibria starting from spherically symmetric black-hole spacetimes expressed in terms of a fully generic and rapidly converging parameterisation: the RZ metric. Within this framework, we have extended the definitions of all of the quantities characterising these equilibria, starting from the concept of the von Zeipel cylinders and up to the possible ranges of the specific angular momenta that are employed to construct families of tori. Within the allowed space of parameters we have then encountered both standard ``single-torus'' solutions, but also non-standard ``double-tori'' solutions. While the properties of the first ones in terms of the presence of a single cusp, of a local pressure maximum and of a varying outer radius, are very similar to those encountered in general relativity, the properties of double-tori solutions are far richer and naturally allow for configurations having the same constant specific angular momentum and hence are potentially easier to produce in nature. The existence of these objects is at present very hypothetical, but these equilibrium tori were to be observed, they would provide very valuable information on the properties of the spacetime and on its deviation from general relativity.

Dynamical system theory is a widely used technique to analyze the asymptotic behavior of a cosmological model. In this method, the equations that describes the dynamics are written in terms of dimensionless variables to make up a set of autonomous first-order differential equations. Then, the asymptotic dynamics of the model are encoded in the fixed points of the autonomous set. Usually, these points are analytical expressions for the variables in terms of the parameters of the model, allowing us to constrain its parameter space. However, analytical treatment could be impossible in some cases. In this work, we give an example of a dark energy (DE) model with no analytical fixed points, a tachyon field coupled to a vector field in an anisotropic Bianchi I background, and propose a numerical description of the parameter space, which allows us to find the bifurcation curves of possible accelerated attractors of the system. This work could serve as a template for numerical analysis of highly complicated dynamical systems.

Long-lived sterile neutrinos can play the role of dark matter. We consider the possibility that such neutrinos form a thermal bath with a singlet scalar, while not being in thermal equilibrium with the Standard Model fields. Eventually, the neutrino dark matter undergoes freeze-out in the dark sector, which can occur in both non-relativistic and relativistic regimes. To account for the latter possibility, we use the full Fermi-Dirac and Bose-Einstein distribution functions with effective chemical potential in the reaction rate computation. This allows us to study the freeze-out process in detail and also obtain the necessary thermalization conditions. We find that relativistic freeze-out occurs in a relatively small part of the parameter space. In contrast to the standard weakly-interacting-massive-particle (WIMP) scenario, the allowed dark matter masses extend to $10^4$ TeV without conflicting perturbativity.

Gravitational vacuum condensate stars, proposed as the endpoint of gravitational collapse consistent with quantum theory, are reviewed. Gravastars are cold, low entropy, maximally compact objects characterized by a surface boundary layer and physical surface tension, instead of an event horizon. Within this thin boundary layer the effective vacuum energy changes rapidly, and the interior of a non-rotating gravastar is a non-singular static patch of de Sitter space with eq. of state p=-rho. Remarkably, essentially this same result is obtained by extrapolating Schwarzschild's 1916 constant density interior solution to its compact limit, showing how the black hole singularity theorems and the Buchdahl compactness bound are evaded. The surface stress tensor on the horizon is determined by a modification of the Lanczos-Israel junction conditions for null hypersurfaces, which is applied to rotating gravastar solutions as well. The fundamental basis for the quantum phase transition at the horizon is the stress tensor of the conformal anomaly, depending upon a new light scalar field in the low energy effective action for gravity. This scalar allows the effective value of the vacuum energy, described as a condensate of an exact 4-form abelian gauge field, to change at the horizon. The resulting effective theory thus replaces the fixed constant Lambda of classical general relativity, and its apparently unnaturally large sensitivity to UV physics, with a dynamical condensate whose ground state value in empty flat space is zero identically. This provides both a natural resolution of the cosmological constant problem and an effective Lagrangian dynamical framework for the boundary layer and interior of gravitational vacuum condensate stars. The status of present observational constraints and prospects for detection of gravastars through their gravitational wave and echo signatures are discussed.

Gravitational waves from neutron star-black hole (NSBH) mergers that undergo tidal disruption provide a potential avenue to study the equation of state of neutron stars and hence the behaviour of matter at its most extreme densities. We present a phenomenological model for the gravitational-wave signature of tidal disruption, which allows us to measure the disruption time. We carry out a study with mock data, assuming an optimistically nearby NSBH event with parameters optimised for measuring the tidal disruption. We show that a two-detector network of 40 km Cosmic Explorer instruments can measure the time of disruption with a precision of 0.5 ms, which corresponds to a constraint on the neutron star radius of 0.7 km (90\% credibility). This radius constraint is wider than the constraint obtained by measuring the tidal deformability of the neutron star of the same system during the inspiral. Moreover, the neutron star radius is likely to be more tightly constrained using binary neutron star mergers. While NSBH mergers are important for the information they provide about stellar and binary astrophysics, they are unlikely to provide insights into nuclear physics beyond what we will already know from binary neutron star mergers.

We derive a formula for the velocity distribution of an axially symmetric galaxy where the mass density is corrected using the mass formula from special relativity. We take some reasonable test mass densities and numerically compute the resulting galaxy rotation curves. We then compare these to the rotation curves obtained from a similar formula without a relativistic correction factor. We find that the correction factor has a small dark-matter like effect. Finally, we compare these to the corresponding Keplerian velocity curves. We find that there is a large discrepancy in this case, where away from the galactic center, up to the galactic edge, the curves computed using our formulas give a noticeably higher velocity.

Awkward Arrays and RDataFrame provide two very different ways of performing calculations at scale. By adding the ability to zero-copy convert between them, users get the best of both. It gives users a better flexibility in mixing different packages and languages in their analysis. In Awkward Array version 2, the ak.to_rdataframe function presents a view of an Awkward Array as an RDataFrame source. This view is generated on demand and the data are not copied. The column readers are generated based on the run-time type of the views. The readers are passed to a generated source derived from ROOT::RDF::RDataSource. The ak.from_rdataframe function converts the selected columns as native Awkward Arrays. The details of the implementation exploiting JIT techniques are discussed. The examples of analysis of data stored in Awkward Arrays via a high-level interface of an RDataFrame are presented. A few examples of the column definition, applying user-defined filters written in C++, and plotting or extracting the columnar data as Awkward Arrays are shown. Current limitations and future plans are discussed.

We propose a new method to detect low-energy neutrinos and low-mass dark matter at or below the MeV scale, through their coherent scatterings from freely falling heavy atoms and the resulting kinematic shifts. We start with a simple calculation for illustration: for $10^7$ heavy atoms of a mass number around 100 with a small recoil energy of 1 meV, the corresponding velocities can reach $0.01, {\rm m/s}$ and produce significant kinematic shifts that can be detected. We then show that the proposed device should be able to probe vast low-energy regions of neutrinos from meV to MeV and can surpass previous limits on sub-MeV dark matter by several orders of magnitude. Such a proposal can be useful to (1) detect sub-MeV-scale dark matter: with $10^2$ atom guns shooting downwards, for example, CsI or lead clusters consisting of $10^{7}$ atoms with a frequency around $10^3$ Hz, it can already be sensitive to scattering cross-sections at the level of $10^{-33 (-34)}\rm{cm}^{2}$ for 1 (0.1) MeV dark matter and surpass current limits. Technological challenges include high-quality atom cluster production and injections. (2) Measure coherent neutrino-nuclei scatterings at the 0.1-1 MeV region for the first time: with $10^4$ atom guns shooting downwards CsI clusters consisting of $10^{11}$ atoms and a frequency of $10^{6}$ Hz. One can expect 10 events from MeV solar neutrinos to be observed per year. Furthermore, (3) this method can be extended to probe very low-energy neutrinos down to the eV-KeV region and may be able to detect the cosmic neutrino background, although it remains challenging.

The framed standard model (FSM), constructed to explain the empirical mass and mixing patterns of quarks and leptons, gives the same result as the standard model in almost all areas in particle physics where it has been successfully applied, except for a few deviations such as the W mass and the g-2 of muons, where experiment is showing departures from what SM predicts. It predicts further the existence of a hidden sector of particles which may function as dark matter. In this paper, we first note that the above results involve the FSM undergoing a vacuum transition at a scale of around 17 MeV, where the vev's of the colour framons which are all nonzero above that scale acquire some vanishing components below it. This implies that the metric pertaining to these vanishing components would vanish also. Consequences should then ensue, mostly in the unknown hidden sector where empirical confirmation is hard at present to come by, but they give small reflections in the standard sector, some of which may have already been seen. However, one notes that if one imagines colour to be embedded, Kaluza-Klein fashion, into a higher dimensional space-time, then this VTR1 would cause 2 of the compactified dimensions to collapse. This might mean that when the universe cooled to the corresponding temperature of $10^{11}$K when it was about $10^{-3}$s old, this VTR1 collapse would cause the 3 spatial dimensions of the universe to expand to compensate. The resultant expansion is estimated, using FSM parameters previously determined from particle physics, to be capable, when extrapolated backwards in time, of bringing the present universe back inside the then horizon, solving thus formally the horizon problem. Besides, VTR1 being a global phenomenon in the FSM, it would switch on and off automatically and simultaneously over all space, thus requiring no additional strategy for a graceful exit.

The cosmological first-order phase transition (FOPT) can be of strong dynamics but with its bubble wall velocity difficult to be determined due to lack of detailed collision terms. Recent holographic numerical simulations of strongly coupled theories with a FOPT prefer a relatively small wall velocity linearly correlated with the phase pressure difference between false and true vacua for a planar wall. In this Letter, we have analytically revealed the non-relativistic limit of a planar/cylindrical/spherical wall expansion of a bubble strongly interacting with the thermal plasma. The planar-wall result reproduces the linear relation found previously in the holographic numerical simulations. The results for cylindrical and spherical walls can be directly tested in future numerical simulations. Once confirmed, the bubble wall velocity for a strongly coupled FOPT can be expressed purely in terms of the hydrodynamics without invoking the underlying microphysics.

If the dark matter is composed of axions, then axion stars are expected to be abundant in the Universe. We demonstrate in fully non-linear (3+1) numerical relativity the instability of compact axion stars due to the electromagnetic Chern-Simons term. We show that above the critical coupling constant $g_{a\gamma}^\mathrm{crit} \propto M_s^{-1.35}$, compact axion stars of mass $M_s$ are unstable. The instability is caused by parametric resonance between the axion and the electromagnetic field. The existence of stable compact axion stars requires approximately Planck-suppressed couplings to photons. If the coupling exceeds the critical value, then all stable axion stars are necessarily non-compact. Unstable axion stars decay leaving behind a less massive, less compact, remnant. The emitted radiation peaks at frequency $\omega \sim 1/R_s$, where $R_s$ is the axion star radius.

This study provides an improved understanding of the penetration probabilities (PPs) in nuclear reactions of light nuclei by correcting the assumptions used in the conventional Gamow factor. The Gamow factor effectively describes the PP in nuclear reactions based on two assumptions: low particle energy than the Coulomb barrier and neglecting the dependence of nuclear interaction potential. However, we find that the assumptions are not valid for light nuclei. As a result of a calculation that excludes the assumptions, we obtain the PP that depends on the nuclear interaction potential depth for the light nuclei. For the potential depth fitted by the experimental fusion cross-section, we present that PPs of light nuclei (D+D, D+T, D+$^3$He, p+D, p+$^6$Li, and p+$^7$Li) become higher than the conventional one near the Coulomb barrier. We also discuss the implications of the modified PP, such as changes in the Gamow peak energy, which determine the measurement of the energy range of the nuclear cross-section in experiments, and the electron screening effect.