Papers for Thursday, Dec 14 2023

Big Bang Nucleosynthesis provides us with an observational insight into the very early Universe. Since this mechanism of light element synthesis comes out of the standard model of particle cosmology which follows directly from General Relativity, it is expected that any modifications to GR will result in deviations in the predicted observable parameters which are mainly, the neutron-to-proton ratio and the baryon-to-photon ratio. We use the measured neutron-to-proton ratio and compare the theoretically obtained expressions to constrain two models in the framework of $ f(T,\mathcal{T}) $ gravity. The theoretically constrained models are then tested against observational data from the Hubble dataset and the $ \Lambda $CDM model to explain the accelerated expansion of the Universe.

We present photometric redshifts (photo-$z$) for the deep wide fields of the Physics of the Accelerating Universe Survey (PAUS), covering an area of $\sim$50 deg$^{2}$, for $\sim$1.8 million objects up to $i_{\textrm{AB}}<23$. The PAUS deep wide fields overlap with the W1 and W3 fields from CFHTLenS and the G09 field from KiDS/GAMA. Photo-$z$ are estimated using the 40 narrow bands (NB) of PAUS and the broad bands (BB) of CFHTLenS and KiDS. We compute the redshifts with the SED template-fitting code BCNZ, with a modification in the calibration technique of the zero-point between the observed and the modelled fluxes, that removes any dependence on spectroscopic redshift samples. We enhance the redshift accuracy by introducing an additional photo-$z$ estimate ($z_{\textrm{b}}$), obtained through the combination of the BCNZ and the BB-only photo-$z$. Comparing with spectroscopic redshifts estimates ($z_{\textrm{s}}$), we obtain a $\sigma_{68} \simeq 0.019$ for all galaxies with $i_{\textrm{AB}}<23$ and a typical bias $|z_{\textrm{b}}-z_{\textrm{s}}|$ smaller than 0.01. For $z_{\textrm{b}} \sim (0.10-0.75)$ we find $\sigma_{68} \simeq (0.003-0.02)$, this is a factor of $10-2$ higher accuracy than the corresponding BB-only results. We obtain similar performance when we split the samples into red (passive) and blue (active) galaxies. We validate the redshift probability $p(z)$ obtained by BCNZ and compare its performance with that of $z_{\textrm{b}}$. These photo-$z$ catalogues will facilitate important science cases, such as the study of galaxy clustering and intrinsic alignment at high redshifts ($z \lesssim 1$) and faint magnitudes.

We study the dipole signal in the spectral index (x) of the differential number counts using quasars in the CatWISE2020 catalog of infrared sources. The index is extracted by using the log-likelihood method. We obtain the value $x=1.579 \pm 0.001$ for a quasar sample of 1355352 sources. We extract the dipole signal in this parameter by employing $\chi^{2}$ minimization, assuming a sky model of x up to the quadrupole term. We find that the dipole amplitude |D| is 0.005 \pm 0.002 and dipole direction (l, b) in Galactic coordinate system equal to $(201.50^{\circ} \pm 27.87^{\circ}, -29.37^{\circ} \pm 19.86^{\circ})$. The direction of dipole anisotropy is found to be very close to the hemispherical power asymmetry $(l,b)=(221^\circ,-27^{\circ})$ in the Cosmic Microwave Background (CMB). We also obtain a signal of quadrupole anisotropy which is correlated with the ecliptic poles and can be attributed to ecliptic bias.}

Astronomers performing polarimetric analysis on astronomical images often have to manually identify locations on their objects of interest, such as galaxies, which exhibit the influence of magnetic forces due to interaction with their environments or inherent processes. These locations are known as Lines of Sight (LoS). Analysing the various lines of sight can provide insight into the electromagnetic nature of the astrophysical object in question and its surroundings. For each LoS, astronomers generate diagnostic plots to map out the variation of the corresponding electromagnetic field, such as those of fractional polarisation and Faraday spectra. However, associating the different LoS diagnostic plots to their positions on an astronomical image requires alternating between the plots and the images. As a result, determining whether the location of the LoS influences its magnetic field variation by analysing its diagnostic plots becomes arduous due to the absence of a direct way of linking the two. PolarVis is an effort towards allowing an almost instant view of the interactive diagnostic plots corresponding to a given line of sight at the click of a button on that line of sight on the image, using an interactive web-based FITS viewer -- JS9.

There is probably not a black hole in the center of the sun. Despite this detail, our goal in this work to convince the reader that this question is interesting and that work studying stars with central black holes is well motivated. If primordial black holes exist then they may exist in sufficiently large numbers to explain the dark matter in the universe. While primordial black holes may form at almost any mass, the asteroid-mass window between $10^{-16} - 10^{-10} ~ \textrm{M}_\odot$ remains a viable dark matter candidate and these black holes could be captured by stars upon formation. Such a star, partially powered by accretion luminosity from a microscopic black hole in its core, has been called a `Hawking star.' Stellar evolution of Hawking stars is highly nontrivial and requires detailed stellar evolution models, which were developed in our recent work. We present here full evolutionary models of solar mass Hawking stars using two accretion schemes: one with a constant radiative efficiency, and one that is new in this work that uses an adaptive radiative efficiency to model the effects of photon trapping.

Observed high multiplicity planetary systems are often tightly packed. Numerical studies indicate that such systems are susceptible to dynamical instabilities. Dynamical instabilities in close-in tightly packed systems, similar to those found in abundance by Kepler, often lead to planet-planet collisions. For sub-Neptunes, the dominant type of observed exoplanets, the planetary mass is concentrated in a rocky core, but the volume is dominated by a low-density gaseous envelope. For these, using the traditional `sticky-sphere' assumption is questionable. Using both N-body integration and smoothed-particle hydrodynamics, we have simulated sub-Neptune collisions for a wide range in realistic kinematic properties such as impact parameters ($b^{\prime}$) and impact velocities ($v_{\rm{im}}$) to study the possible outcomes in detail. We find that the majority ($\sim 76\%$) of the collisions with kinematic properties similar to what is expected from dynamical instabilities in multiplanet systems may not lead to mergers of sub-Neptunes. Instead, the sub-Neptunes separate from each other, often with significant atmosphere loss. When mergers do occur, they can involve significant mass loss even from the core and can sometimes lead to complete disruption of one or both planets. Sub-Neptunes merge or disrupt if $b^{\prime}<b_{\rm{c}}$, a critical value dependent on $ v_{\rm{im}}/v_{\rm{esc}}$, where $v_{\rm{esc}}$ is the escape velocity from the surface of the hypothetical merged planet assuming sticky-sphere. For $ v_{\rm{im}}/v_{\rm{esc}}\lesssim2.5$, $b_{\rm{c}}\propto (v_{\rm{im}}/v_{\rm{esc}})^{-2}$, and collisions with $b^{\prime}<b_{\rm{c}}$ typically leads to mergers. On the other hand, for $ v_{\rm{im}}/v_{\rm{esc}}\gtrsim2.5$, $b_{\rm{c}}\propto v_{\rm{im}}/v_{\rm{esc}}$, and the collisions with $b^{\prime}<b_{\rm{c}}$ can result in complete destruction of one or both sub-Neptunes.

The flavor composition of TeV--PeV astrophysical neutrinos, i.e., the proportion of neutrinos of different flavors in their flux, is a versatile probe of high-energy astrophysics and fundamental physics. Because flavor identification is challenging and the number of detected high-energy astrophysical neutrinos is limited, so far measurements of the flavor composition have represented an average over the range of observed neutrino energies. Yet, this washes out the potential existence of changes in the flavor composition with energy and weakens our sensitivity to the many models that posit them. For the first time, we measure the energy dependence of the flavor composition, looking for a transition from low to high energies. Our present-day measurements, based on the 7.5-year public sample of IceCube High-Energy Starting Events (HESE), find no evidence of a flavor transition. The observation of HESE and through-going muons jointly by next-generation neutrino telescopes Baikal-GVD, IceCube-Gen2, KM3NeT, P-ONE, TAMBO, and TRIDENT may identify a flavor transition around 200TeV by 2030. By 2040, we could infer the flavor composition with which neutrinos are produced with enough precision to establish the transition from neutrino production via the full pion decay chain at low energies to muon-damped pion decay at high energies.

We describe a testbed to characterize the optical response of compact superconducting on-chip spectrometers in development for the Experiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) mission. EXCLAIM is a balloonborne far-infrared experiment to probe the CO and CII emission lines in galaxies from redshift 3.5 to the present. The spectrometer, called u-Spec, comprises a diffraction grating on a silicon chip coupled to kinetic inductance detectors (KIDs) read out via a single microwave feedline. We use a prototype spectrometer for EXCLAIM to demonstrate our ability to characterize the spectrometers spectral response using a photomixer source. We utilize an on-chip reference detector to normalize relative to spectral structure from the off-chip optics and a silicon etalon to calibrate the absolute frequency.

Mass and spin of massive black holes (BHs) at the centre of galaxies evolve due to gas accretion and mergers with other BHs. Besides affecting e.g. the evolution of relativistic jets, the BH spin determines the efficiency with which the BH radiates energy. Using cosmological, hydrodynamical simulations, we investigate the evolution of the BH spin across cosmic time and its role in controlling the joint growth of supermassive BHs and their host galaxies. We implement a sub-resolution prescription that models the BH spin, accounting for both BH coalescence and misaligned accretion through a geometrically thin, optically thick disc. We investigate how BH spin evolves in two idealised setups, in zoomed-in simulations, and in a cosmological volume. The latter simulation allows us to retrieve statistically robust results as for the evolution and distribution of BH spins as a function of BH properties. We find that BHs with $M_{\rm BH}\lesssim 2 \times 10^{7}\;{\rm M}_{\odot}$ grow through gas accretion, occurring mostly in a coherent fashion that favours spin-up. Above $M_{\rm BH}\gtrsim 2 \times 10^{7}~{\rm M}_{\odot}$ the gas angular momentum directions of subsequent accretion episodes are often uncorrelated with each other. The probability of counter-rotating accretion and hence spin-down increases with BH mass. In the latter mass regime, BH coalescence plays an important role. The spin magnitude displays a wide variety of histories, depending on the dynamical state of the gas feeding the BH and the relative contribution of mergers and gas accretion. As a result of their combined effect, we observe a broad range of values of the spin magnitude at the high-mass end. Our predictions for the distributions of BH spin and spin-dependent radiative efficiency as a function of BH mass are in very good agreement with observations.

Massive (>~ 8 solar masses) stars are the progenitors of many astrophysical systems, yet key aspects of their structure and evolution are poorly understood. Asteroseismology has the potential to solve these open puzzles, however, sampling both the short period pulsations and long period beat patterns of massive stars poses many observational challenges. Ground-based single-site observations require years or decades to discern the main oscillation modes. Multi-site campaigns were able to shorten this time span, but have not been able to scale up to population studies on samples of objects. Space-based observations can achieve both continuous sampling and observe large numbers of objects, however, most lack the multi-band data that is often necessary for mode identification and removing model degeneracies. Here, we develop and test a new ground-based observational strategy for discerning and identifying the main oscillation modes of a massive star in a few months, in a way that can be scaled to large samples. We do so using the Las Cumbres Observatory - a unique facility consisting of robotic, homogeneous telescopes operating as a global network, overcoming most of the challenges of previous multi-site efforts, but presenting new challenges which we tailor our strategy to address. This work serves as the proof of concept for the Global Asteroseismology Project, which aims to move massive star asteroseismology from single-objects to bulk studies, unleashing its full potential in constraining stellar structure and evolution models. This work also demonstrates the ability of the Las Cumbres Observatory to perform multi-site continuous observations for various science goals.

We present a thorough study of the Changing-Look Active Galactic Nucleus (CL-AGN) Mrk 1018, utilizing an extensive dataset spanning optical, UV, and X-ray spectro-photometric data from 2005 to 2019. We analysed X-ray spectra and broad-band photometry, and performed optical-to-X-ray spectral energy distribution (SED) fitting to comprehend the observed changing-look behaviour. We found that over the 14 years in analysis, significant changes in X-ray spectra occurred, as the hardness ratio increases by a factor of ~2. We validated also the broad-band dimming, with optical, UV, and X-ray luminosities decreasing by factors of >7, >24 and ~9, respectively. These dims are attributed to the declining UV emission. We described the X-ray spectra with a two-Comptonization model, revealing a consistent hot comptonizing medium but a cooling warm component. This cooling, linked to the weakening of the magnetic fields in the accretion disk, explains the UV dimming. We propose that the weakening is caused by the formation of a jet, in turn originated from the change of state of the inner accretion flow. Our optical-to-X-ray SED fitting supports this conclusion, as the normalised accretion rate is super-critical ($\mu=$0.06>0.02) in the bright state and sub-critical ($\mu=$0.01<0.02) in the faint state. Instabilities arising at the interface of the state-transition are able to reduce the viscous timescale to the observed ~10 years of Mrk 1018 variability. We explored a possible triggering mechanism for this state transition, involving gaseous clouds pushed onto the AGN sub-pc regions by a recent merging event or by cold chaotic accretion. This scenario, if validated by future simulations, could enhance our understanding of CL-AGN and raises questions about an accretion rate of ~0.02, coupled with minor disturbances in the accretion disk, being the primary factor in the changing-look phenomenon.

Under the assumption of a simple and time-invariant gravitational potential, many Galactic dynamics techniques infer the Milky Way's mass and dark matter distribution from stellar kinematic observations. These methods typically rely on parameterized potential models of the Galaxy and must take into account non-trivial survey selection effects, because they make use of the density of stars in phase space. Large-scale spectroscopic surveys now supply information beyond kinematics in the form of precise stellar label measurements (especially element abundances). These element abundances are known to correlate with orbital actions or other dynamical invariants. Here, we use the Orbital Torus Imaging (OTI) framework that uses abundance gradients in phase space to map orbits. In many cases these gradients can be measured without detailed knowledge of the selection function. We use stellar surface abundances from the APOGEE survey combined with kinematic data from the Gaia mission. Our method reveals the vertical ($z$-direction) orbit structure in the Galaxy and enables empirical measurements of the vertical acceleration field and orbital frequencies in the disk. From these measurements, we infer the total surface mass density, $\Sigma$, and midplane volume density, $\rho_0$, as a function of Galactocentric radius and height. Around the Sun, we find $\Sigma_{\odot}(z=1.1$ kpc)$=72^{+6}_{-9}$M$_{\odot}$pc$^{-2}$ and $\rho_{\odot}(z=0)=0.081^{+0.015}_{-0.009}$ M$_{\odot}$pc$^{-3}$ using the most constraining abundance ratio, [Mg/Fe]. This corresponds to a dark matter contribution in surface density of $\Sigma_{\odot,\mathrm{DM}}(z=1.1$ kpc)$=24\pm4$ M$_{\odot}$pc$^{-2}$, and in total volume mass density of $\rho_{\odot,\mathrm{DM}}(z=0)=0.011\pm0.002$ M$_{\odot}$pc$^{-3}$. Moreover, using these mass density values we estimate the scale length of the low-$\alpha$ disc to be $h_R=2.24\pm0.06$kpc.

We present our analysis of VLT/UVES and X-shooter observations of six very metal-poor stars, including four stars at around [Fe/H]=-3 in the Fornax and Carina dwarf spheroidal galaxies (dSph). Until now, this metallicity range in these two galaxies was either hardly or not yet investigated. The chemical abundances of 25 elements are presented, based on 1D/LTE model atmospheres. We discuss the different elemental groups, and find that alpha- and iron-peak elements in these two systems are generally in good agreement with the Milky Way halo at the same metallicity. Our analysis reveals that none of the six stars we studied exhibit carbon enhancement, which is noteworthy given the prevalence of carbon-enhanced metal-poor (CEMP-no; no Ba enhancement) stars in the Galaxy at similarly low metallicities. Our compilation of literature data shows that the fraction of CEMP-no stars in dSphs is significantly lower than in the Milky Way, and than in ultra faint dwarf galaxies. Furthermore, we report the discovery of the lowest metallicity, [Fe/H]=-2.92, r-process rich (r-I) star in a dSph galaxy. This star, fnx_06_019, has [Eu/Fe]=+0.8, and also shows enhancement of La, Nd, and Dy, [X/Fe]>+0.5. Our new data in Carina and Fornax help to populate the extremely low metallicity range in dSph galaxies, and add onto the evidence of a low fraction of CEMP-no stars in these systems.

We explore how dynamical friction in an ultralight dark matter (ULDM) background is affected by dark matter self-interactions. We calculate the force of dynamical friction on a point mass moving through a uniform ULDM background with self-interactions, finding that the force of dynamical friction vanishes for sufficiently strong repulsive self-interactions. Using the pseudospectral solver $\texttt{UltraDark.jl}$, we show with simulations that reasonable values of the ULDM self-interaction strength and particle mass cause $\mathcal{O}(1)$ differences in the acceleration of an object like a supermassive black hole (SMBH) traveling near the center of a soliton, relative to the case with no self-interactions. For example, repulsive self-interactions with $\lambda = 10^{-90}$ yield a deceleration due to dynamical friction $\approx70\%$ smaller than a model with no self-interactions. We discuss the observational implications of our results for SMBHs near soliton centers and for massive satellite galaxies falling into ultralight axion halos and show that outcomes are dependent on whether a self-interaction is present or not.

In this article, I will present some figures and milestones of the written production of the Instituto Argentino de Radioastronomia (IAR), as well as a personal review of the scientific achievements carried out in recent years by the researchers working at the IAR. I will also briefly describe the scientific objectives of the IAR's flagship project, the Multipurpose Interferometric Array (MIA), in the context of the instrumental projects that have lately been or are being installed on Argentine soil.

In this paper, we perform an investigation into the effect of the string radius of curvature $R_\mathrm{\,Gaussian}$ on the magnitude and relative magnitude of the massive and massless radiation from axion (global) string configurations, motivated by qualitative observations from string network simulations. We construct initial conditions from travelling wave solutions on a global string for two colliding Gaussians, performing parameter scans over amplitude $A$ and standard deviation $\sigma_\mathrm{d}$. We show that the energy emitted via massless radiation obeys a power law $E_\mathrm{massless} \appropto A^{\gamma}$, where the coefficient $\gamma$ depends on the curvature regime. Massive radiation is exponentially suppressed approximately as $E_{\mathrm{massive}} \appropto e^{-\zeta R_\mathrm{\,Gaussian}}$ in the quasi-linear regime $\sigma_\mathrm{d} \gg \delta$ and exhibits power-law decay $E_{\mathrm{massive}} \appropto (R_\mathrm{\,Gaussian})^{-\gamma}$ in the nonlinear regime where $\sigma_\mathrm{d} \lesssim 2\delta$, with different $\gamma$ in different regimes of $R_\mathrm{\,Gaussian}$. In certain regions of the nonlinear regime, massive particle radiation comprises up to 50\% of the total energy emitted. Drawing on a known parallel between axion radiation from global strings and gravitational radiation from Abelian-Higgs strings, this suggests that massive particle radiation channel may become of equal significance to the massless (gravitational) channel for nonlinear burst signals where $R < \sigma_\mathrm{d}$, unless we are in the regime where additional loops are generated. We also estimate the spectral index $q$ of the axion radiation for different amplitudes, showing that a higher proportion of radiation is emitted in high frequency modes as the curvature increases, bounded by $q \gtrsim 1$ for the configurations studied.

The structure and dynamics of the star-forming disk of the Small Magellanic Cloud (SMC) have long confounded us. The SMC is widely used as a prototype for galactic physics at low metallicity, and yet we fundamentally lack an understanding of the structure of its interstellar medium (ISM). In this work, we present a new model for the SMC by comparing the kinematics of young, massive stars with the structure of the ISM traced by high-resolution observations of neutral atomic hydrogen (HI) from the Galactic Australian Square Kilometer Array Pathfinder survey (GASKAP-HI). Specifically, we identify thousands of young, massive stars with precise radial velocity constraints from the Gaia and APOGEE surveys and match these stars to the ISM structures in which they likely formed. By comparing the average dust extinction towards these stars, we find evidence that the SMC is composed of two structures with distinct stellar and gaseous chemical compositions. We construct a simple model that successfully reproduces the observations and shows that the ISM of the SMC is arranged into two, superimposed, star-forming systems with similar gas mass separated by ~5 kpc along the line of sight.

FRB 20220912A is a repeating Fast Radio Burst (FRB) that was discovered in Fall 2022 and remained highly active for several months. We report the detection of 35 FRBs from 541 hours of follow-up observations of this source using the recently refurbished Allen Telescope Array, covering 1344 MHz of bandwidth primarily centered at 1572 MHz. All 35 FRBs were detected in the lower half of the band with non-detections in the upper half and covered fluences from 4-431 Jy-ms (median$=$48.27 Jy-ms). We find consistency with previous repeater studies for a range of spectrotemporal features including: bursts with downward frequency drifting over time; a positive correlation between bandwidth and center frequency; and a decrease in sub-burst duration over time. We report an apparent decrease in the center frequency of observed bursts over the 2 months of the observing campaign (corresponding to a drop of $6.21\pm 0.76$ MHz per day). We predict a cut-off fluence for FRB 20220912A of $F_\textrm{max}\lesssim 10^4$ Jy-ms, for this source to be consistent with the all-sky rate, and find that FRB 20220912A significantly contributed to the all-sky FRB rate at a level of a few percent for fluences of $\sim$100 Jy-ms. Finally, we investigate characteristic timescales and sub-burst periodicities and find a) a median inter-subburst timescale of 5.82$\pm$1.16 ms in the multi-component bursts and b) no evidence of strict periodicity even in the most evenly-spaced multi-component burst in the sample. Our results demonstrate the importance of wideband observations of FRBs, and provide an important set of observational parameters against which to compare FRB progenitor and emission mechanism models.

We report on IFU measurements of the host of the radio source 4C+37.11. This massive elliptical contains the only resolved double compact nucleus at pc-scale separation, likely a bound supermassive black hole binary (SMBHB). $i$-band photometry and GMOS-N IFU spectroscopy show that the galaxy has a large $r_b=1.5^{\prime\prime}$ core and that the stellar velocity dispersion increases inside of a radius of influence $r_{\rm SOI} \approx 1.3^{\prime\prime}$. Jeans Anisotropic Modeling analysis of the core infers a total SMBHB mass of $2.8^{+0.8}_{-0.8} \times 10^{10}M_\odot$, making this one of the most massive black hole systems known. Our data indicate that there has been significant scouring of the central kpc of the host galaxy.

Previous work on the abundances of C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in low-alpha (accreted) and high-alpha (in situ born) halo stars is extended to include the abundances of Sc, V, and Co, enabling us to study the nucleosynthesis of all iron-peak elements along with the lighter elements. The Sc, V, and Co abundances were determined from a 1D MARCS model-atmosphere analysis of equivalent widths of atomic lines in high signal-to-noise, high resolution spectra assuming local thermodynamic equilibrium (LTE). In addition, new 3D and/or non-LTE calculations were used to correct the 1D LTE abundances for several elements including consistent 3D non-LTE calculations for Mg. The two populations of accreted and in situ born stars are well separated in diagrams showing [Sc/Fe], [V/Fe], and [Co/Fe] as a function of [Fe/H]. The [X/Mg] versus [Mg/H] trends for high-alpha and low-alpha stars were used to determine the yields of core-collapse and Type Ia supernovae. The largest Type Ia contribution occurs for Cr, Mn, and Fe, whereas Cu is a pure core-collapse element. Sc, Ti, V, Co, Ni, and Zn represent intermediate cases. A comparison with yields calculated for supernova models shows poor agreement for the core-collapse yields. The Ia yields suggest that sub-Chandrasekhar-mass Type Ia supernovae provide a dominant contribution to the chemical evolution of the host galaxies of the low-alpha stars. A substructure in the abundances and kinematics of the low-alpha stars suggests that they arise from at least two different satellite accretion events, Gaia-Sausage-Enceladus and Thamnos.

Compilation of papers presented by the VERITAS Collaboration at the 38th International Cosmic Ray Conference (ICRC), held July 26 through August 3, 2023 in Nagoya, Japan.

We present a sample of 1165 extreme emission-line galaxies (EELGs) at 4<z<9 selected using James Webb Space Telescope (JWST) NIRCam photometry in the Cosmic Evolution Early Release Science (CEERS) program. We use a simple method to photometrically identify EELGs with Hb + [OIII] (combined) or Ha emission of observed-frame equivalent width EW >5000 AA. JWST/NIRSpec spectroscopic observations of a subset (34) of the photometrically selected EELGs validate our selection method: all spectroscopically observed EELGs confirm our photometric identification of extreme emission, including some cases where the SED-derived photometric redshifts are incorrect. We find that the medium-band F410M filter in CEERS is particularly efficient at identifying EELGs, both in terms of including emission lines in the filter and in correctly identifying the continuum between Hb + [OIII] and Ha in the neighboring broad-band filters. We present examples of EELGs that could be incorrectly classified at ultra-high redshift (z>12) as a result of extreme Hb + [OIII] emission blended across the reddest photometric filters. We compare the EELGs to the broader (sub-extreme) galaxy population in the same redshift range and find that they are consistent with being the bluer, high equivalent width tail of a broader population of emission-line galaxies. The highest-EW EELGs tend to have more compact emission-line sizes than continuum sizes, suggesting that active galactic nuclei are responsible for at least some of the most extreme EELGs. Photometrically inferred emission-line ratios are consistent with ISM conditions with high ionization and moderately low metallicity, consistent with previous spectroscopic studies.

We investigate the bright CO fundamental emission in the central regions of five Class 0 protostars using the JWST's Near-Infrared Spectrograph (NIRSpec) and provide clues to what processes excite the gas. CO line emission images are extracted for a forest of $\sim$150 ro-vibrational transitions from two vibrational bands, $v=1-0$ and $v=2-1$. However, ${}^{13}$CO is not detected, and thus we can only statistically constrain the ${}^{12}$CO optical depth. Using noise measurements to determine upper limits to the ${}^{13}$CO emission, the flux ratio of ${}^{12}$CO/${}^{13}$CO indicates that the ${}^{12}$CO emission itself is not optically thick for ro-vibrational transitions with upper state rotational quantum number $J_u \geq 15$. We construct population diagrams to estimate the rotational temperature and number of molecules from extinction-corrected CO line fluxes assuming CO emission is optically thin. Two different temperature components are required for $v=1$ ($\sim600-1000$ K and $\sim1500-3500$ K), while one hotter component is required for $v=2$ ($\sim2000-6000$ K). The vibrational temperature is $\sim 900$ K among our sources and shows no trend with luminosity. Using vibrational temperatures and the inferred total amount of CO molecules for our sources, the total warm gas mass correlates strongly with luminosity ranging from $\sim$0.1 $\rm M_{Earth}$ for the low-mass protostars to $\sim$1 M$_{\rm sun}$ for the high-mass protostars. Interpreting the distribution of gas column densities and temperatures depends on radiative and chemical processes affecting CO. The presence of a $v=2$ population may indicate CO gas radiatively excited. Selective UV photodissociation of CO isotopologues around our high-mass sources may explain their depletion of ${}^{13}$CO.

In the framework of the ongoing project, aimed at the systematical studying galaxies in nearby voids, we conducted spectroscopy with the Southern African Large Telescope (SALT) of 62 objects from the Nearby Void Galaxy (NVG) sample. They include 8 remaining objects of the 60 preselected candidates to eXtremely Metal-Poor (XMP) dwarfs, two known void XMP dwarfs and 52 void dwarfs residing within the Local Volume. For 47 galaxies residing in the nearby voids, we obtained spectra of the diverse quality. For 42 of them, we detected the Hydrogen and Oxygen lines that allowed us to get estimates of O/H in the observed HII regions. For 12 of the 42 objects, we detected the faint line [Oiii]4363, that allowed us to directly derive the electron temperature T_e and obtain their gas O/H by the direct method. 14 objects with the undetected [Oiii]4363 line fall to the lowest metallicities range (12+log(O/H) < 7.5 dex). For them, we use a carefully checked new empirical 'Strong line' method of Izotov et al. For 14 other objects with only strong lines detected and with 12+log(O/H) of ~7.5-8.0 dex, we used the modified version of 'semi-empirical' method of Izotov and Thuan. It accounts for effect of the excitation parameter O32 on T_e. 16 new galaxies are found with parameter 12+log(O/H) < 7.39 dex. Of them, four have 12+log(O/H) = 7.07 - 7.20 dex. Of the 60 observed NVG objects, 15 have mistaken radial velocities in HyperLEDA. They do not reside in the nearby voids.

The Planck space mission has observed the first three rotational lines of emission of Galactic CO. Those maps, however, are either noisy, or contaminated by astrophysical emissions from different origin. We revisit those data products to deliver new full-sky CO maps with low astrophysical contamination and significantly enhanced noise properties. To that effect, a specific pipeline is designed to evaluate and postprocess the existing Planck Galactic CO maps. Specifically, we use an extension of the Generalized Needlet Internal Linear Combination method to extract multi-component astrophysical emissions from multi-frequency observations. Well characterized, clean CO full-sky maps at $10^\prime$ angular resolution are produced. These maps are made available to the scientific community and can be used to trace CO emission over the entire sky, and to generate sky simulations in preparation for future CMB observations.

Based on 4,\,098 very metal-poor (VMP) stars with 6D phase-space and chemical information from \textit{Gaia} DR3 and LAMOST DR9 as tracers, we apply an unsupervised machine learning algorithm, Shared Nearest Neighbor (SNN), to identify stellar groups in the action-energy (\textbf{\textit{J}}-$E$) space. We detect seven previously known mergers in local samples, including Helmi Stream, Gaia-Sausage-Enceladus (GSE), Metal-weak Thick Disk (MWTD), Pontus, Wukong, Thamnos, and I'itoi+Sequoia+Arjuna. According to energy, we further divide GSE and Wukong into smaller parts to explore the orbital characteristics of individual fragments. Similarly, the division of Thamnos is based on action. It can be found that the apocentric distances of GSE parts of high and medium energy levels are located at $29.5\pm3.6\,{\rm kpc}$ and $13.0\pm2.7\,{\rm kpc}$, respectively, which suggests that GSE could account for breaks in the density profile of the Galactic halo at both $\approx30$\,kpc and $15\text{-}18$\,kpc. The VMP stars of MWTD move along prograde orbits with larger eccentricities than those of its more metal-rich stars, which indicates that the VMP part of MWTD may be formed by accreting with dwarf galaxies. Finally, we summarize all substructures discovered in our local VMP samples. Our results provide a reference for the formation and evolution of the inner halo of the Milky Way (MW).

Never before has the detection and characterization of exoplanets via transit photometry been as promising and feasible as it is now, due to the increasing breadth and sensitivity of time domain optical surveys. Past works have made use of phase-folded stellar lightcurves in order to study the properties of exoplanet transits, because this provides the highest signal that a transit is present at a given period and ephemeris. Characterizing transits on an individual, rather than phase-folded, basis is much more challenging due to the often low signal-to-noise ratio (SNR) of lightcurves, missing data, and low sampling rates. However, by phase-folding a lightcurve we implicitly assume that all transits have the same expected properties, and lose all information about the nature and variability of the transits. We miss the natural variability in transit shapes, or even the deliberate or inadvertent modification of transit signals by an extraterrestrial civilization (for example, via laser emission or orbiting megastructures). In this work, we develop an algorithm to search stellar lightcurves for individual anomalous (in timing or depth) transits, and we report the results of that search for 218 confirmed transiting exoplanet systems from Kepler.

We developed a 2-mm-thick CdTe double-sided strip detector (CdTe-DSD) with a 250 um strip pitch, which has high spatial resolution with a uniform large imaging area of 10 cm$^2$ and high energy resolution with high detection efficiency in tens to hundreds keV. The detector can be employed in a wide variety of fields for quantitative observations of hard X-ray and soft gamma-ray with spectroscopic imaging, for example, space observation, nuclear medicine, and non-destructive elemental analysis. This detector is thicker than the 0.75-mm-thick one previously developed by a factor of $\sim$2.7, thus providing better detection efficiency for hard X-rays and soft gamma rays. The increased thickness could potentially enhance bias-induced polarization if we do not apply sufficient bias and if we do not operate at a low temperature, but the polarization is not evident in our detector when a high voltage of 500 V is applied to the CdTe diode and the temperature is maintained at 20 $^\circ$C during one-day experiments. The ''Depth Of Interaction'' (DOI) dependence due to the CdTe diode's poor carrier-transport property is also more significant, resulting in much DOI information while complicated detector responses such as charge sharings or low-energy tails that exacerbate the loss in the energy resolution. In this paper, we developed 2-mm-thick CdTe-DSDs, studied their response, and evaluated their energy resolution, spatial resolution, and uniformity. We also constructed a theoretical model to understand the detector response theoretically, resulting in reconstructing the DOI with an accuracy of 100 um while estimating the carrier-transport property. We realized the detector that has high energy resolution and high 3D spatial resolution with a uniform large imaging area.

The coalescence of binary neutron stars can yield the expulsion of a fast-moving, quasi-isotropic material, which may induce thermal radiation and give rise to kilonova emission. Moreover, the interaction between the ejected material and the surrounding environment generates an external shock, which can result in a long-lasting radio signal that persists for several decades following the merger. In contrast to supernova ejecta, kilonova ejecta exhibits a relatively lesser mass and higher velocity, and its expansion may ultimately result in the ejecta density becoming so low that the medium particle can freely pass through the ejecta. Thereby it would lead to a kind of incomplete sweeping on the interstellar medium. Employing a toy model, our investigation reveals that such incomplete sweeping may considerably diminish the late-time radio radiation power, irrespective of whether the binary neutron star merger results in the formation of a black hole or a neutron star. Our findings, thus, imply that the previously reported radio upper limits for certain short gamma-ray bursts may not necessarily place stringent constraints on the presence of a long-lived magnetar remnant in these short GRBs.

We examine the evolution of ion-beam Weibel instability at strong collisionless shocks in weakly magnetized media. We find that a finite background magnetic field substantially affects both linear and nonlinear phases of the instability, depending on whether the background electrons behave magnetized or not. Particle-in-cell simulations for magnetized electrons identify a dynamo-like mechanism of magnetic field amplification, which eventually leads to spontaneous magnetic reconnection. We conclude that this scenario is applicable to typical young supernova remnant shocks.

Primordial magnetogenesis is an intriguing possibility to explain the origin of intergalactic magnetic fields (IGMFs). However, the baryon isocurvature problem has recently been pointed out, ruling out all magnetogenesis models operating above the electroweak scale. In this letter, we show that lower-scale inflationary scenarios with a Chern-Simons coupling can evade this problem. We propose concrete inflationary models whose reheating temperatures are lower than the electroweak scale and numerically compute the amount of magnetic fields generated during inflation and reheating. We find that, for lower reheating temperatures, the magnetic helicity decreases significantly. It is also possible to generate fully helical magnetic fields by modifying the inflaton potential. In both cases, the produced magnetic fields can be strong enough to explain the observed IGMFs, while avoiding the baryon isocurvature problem.

Evolutionary sequences of AGB stars with initial masses on the main sequence $M_\mathrm{ZAMS}=1.5M_\odot$, $2M_\odot$ and $3M_\odot$ were computed for the initial metallicity $Z=0.014$. Selected models of evolutionary sequences with envelopes under thermal equilibrium were used as initial conditions for calculation of nonlinear stellar pulsations. The hydrodynamic models of each evolutionary sequence are shown to concentrate along the continuous line in the period-radius and period-luminosity diagrams. The theoretical period-radius and period-luminosity relations differ from one another for different main-sequence star masses because the stellar luminosity of AGB stars depends on the degenerate carbon core mass which increases with increasing $M_\mathrm{ZAMS}$. In hydrodynamic models of evolutionary sequences $M_\mathrm{ZAMS}=2M_\odot$ and $M_\mathrm{ZAMS}=3M_\odot$ the periods of the first overtone pulsators are $86~\textrm{d}\le\Pi\le 123~\textrm{d}$ and $174~\textrm{d}\le\Pi\le 204~\textrm{d}$, whereas all models of the evolutionary sequence $M_\mathrm{ZAMS}=1.5M_\odot$ oscillate in the fundamental mode. Fairly regular radial oscillations exist in stars with pulsation periods $\Pi\lesssim 500$ d. In models with longer periods the amplitude rapidly increases with increasing $\Pi$ and oscillations become irregular.

Intensity interferometry for astrophysical observations has gained increasing interest in the last decade. The method of correlating photon fluxes at different telescopes for high resolution astronomy without access to the phase of the incoming light is insensitive to atmospheric turbulence and doesn't require high-precision optical path control. The necessary large collection areas can be provided by Imaging Atmospheric Cherenkov Telescopes. Implementation of intensity interferometers to existing telescope systems such as VERITAS and MAGIC has proven to be successful for high-resolution imaging of stars. In April 2022 we equipped two telescopes of the H.E.S.S. array in Namibia with an intensity interferometry setup to measure southern sky stars and star systems during the bright moon period. We mounted an external optical system to the lid of the telescope cameras, which splits the incoming light and feeds it into two photomultipliers in order to measure the zero-baseline correlation within one telescope in addition to the cross correlation between the telescopes. The optical elements are motorised, which enables live correction of tracking inaccuracies of the telescopes. During the campaign we measured the spatial correlation curves and thereby the angular diameters of {\lambda} Sco (Shaula) and {\sigma} Sgr (Nunki), while we also performed systematic studies of our interferometer using the multiple star system of {\alpha} Cru (Acrux).

In cosmological analyses, precise redshift determination remains pivotal for understanding cosmic evolution. However, with only a fraction of galaxies having spectroscopic redshifts (spec-$z$s), the challenge lies in estimating redshifts for a larger number. To address this, photometry-based redshift (photo-$z$) estimation, employing machine learning algorithms, is a viable solution. Identifying the limitations of previous methods, this study focuses on implementing deep learning (DL) techniques within the Kilo-Degree Survey (KiDS) Bright Galaxy Sample for more accurate photo-$z$ estimations. Comparing our new DL-based model against prior `shallow' neural networks, we showcase improvements in redshift accuracy. Our model gives mean photo-$z$ bias $\langle \Delta z\rangle= 10^{-3}$ and scatter $\mathrm{SMAD}(\Delta z)=0.016$, where $\Delta z = (z_\mathrm{phot}-z_\mathrm{spec})/(1+z_\mathrm{spec})$. This research highlights the promising role of DL in revolutionizing photo-$z$ estimation.

From late September 2017 to February 2018, the Be X-ray binary (BeXB) Swift J0243.6+6124 underwent an unprecedently bright giant outburst. The reported X-ray luminosities were so high that the system was classified as an Ultraluminous X-ray source (ULX). It was also the first BeXB pulsar showing radio jet emission. The source was not only bright in X-rays and radio, but also in optical and UV wavelenghts. In this paper we aim to understand the origin of the observed optical/UV fluxes simultaneous to the X-ray emission. We studied the optical/UV light curves in comparison with the X-ray fluxes along the outburst, considering the main mechanisms that can explain the optical/UV emission in X-ray binaries. Due to the tight correlation observed between the optical/UV and X-ray light curves, reprocessing of X-rays seems to be the most plausible explanation. We calculated the timescales of the light curves decays and studied the correlation indexes between the optical and X-ray emission. Finally, we built a physical model considering X-ray heating of the surface of the donor star, irradiation of the accretion disk, and emission from a viscously heated accretion disk, in order to reproduce the observed optical/UV SEDs along the outburst. We considered in our model that the Be circumstellar disk was co-planar to the orbit, and then we neglected its irradiation in the current model. As an input of the model, we used as incident X-ray luminosities those calculated from the bolometric X-ray fluxes obtained from the spectral fit of the Swift/XRT and BAT observations. We conclude that reprocessing of X-rays as X-ray heating of the Be star surface and irradiation of the accretion disk are the two main mechanisms that can reproduce the observed optical/UV emission during the 2017-2018 giant outburst of Swift J0243.6+6124.

The early Universe, spanning 400,000 to 400 million years after the Big Bang ($z\approx1100-11$), has been left largely unexplored as the light from luminous objects is too faint to be observed directly. While new experiments are pushing the redshift limit of direct observations, measurements in the low-frequency radio band promise to probe early star and black hole formation via observations of the hydrogen 21-cm line. In this work we explore synergies between 21-cm data from the HERA and SARAS 3 experiments and observations of the unresolved radio and X-ray backgrounds using multi-wavelength Bayesian analysis. We use the combined data set to constrain properties of Population II and Population III stars as well as early X-ray and radio sources. The joint fit reveals a 68 percentile disfavouring of Population III star formation efficiencies $\gtrsim5.5\%$. We also show how the 21-cm and the X-ray background data synergistically constrain opposite ends of the X-ray efficiency prior distribution to produce a peak in the 1D posterior of the X-ray luminosity per star formation rate. We find (at 68\% confidence) that early galaxies were likely 0.33 to 311 times as X-ray efficient as present-day starburst galaxies. We also show that the functional posteriors from our joint fit rule out global 21-cm signals deeper than $\lesssim-225\ \mathrm{mK}$ and power spectrum amplitudes at $k=0.34\ h\mathrm{Mpc^{-1}}$ greater than $\Delta_{21}^2 \gtrsim 4814\ \mathrm{mK}^2$ with $3\sigma$ confidence.

The most energetic astrophysical sources in the Milky Way, cosmic accelerators capable of producing high-energy cosmic rays, have resisted discovery for over a century. Up to now, astrophysicists sought these sources mainly by scouring the Galaxy for the gamma rays they are expected to emit. In 2023, the IceCube Neutrino Observatory discovered high-energy neutrinos from the Milky Way, inaugurating a telltale stream of evidence of cosmic-ray production and interaction in the Galaxy.

Cas I is a LV dIrr with a wide range of suggested distances. Tikhonov (2019), using the HST images and the TRGB method, places Cas I at D = 1.6+-0.1 Mpc. Besides, he estimates the stellar metallicity of Cas I at the level of z ~ 0.0004 (Z ~ Zo/50). Such a nearby extremely low-metallicity dwarf, if real, would be a very valuable object for detailed studies. An alternative TRGB distance of Cas I, of 4.5+-0.2 Mpc, based on the deeper HST images, was presented in the EDD. It places Cas I midway between IC342 (D ~ 3.3 Mpc) and Maffei 1 (D ~ 5.7 Mpc). We wish to check the suggested extremely low metallicity of Cas I, to improve the estimate of the large MW extinction and to improve the distance estimate to Cas~I. We use the SAO 6-m telescope spectroscopy to estimate gas metallicity in two HII regions in Cas I and to derive, via their observed Balmer decrements, the independent upper limit to the value of the MW extinction. We derive values of 12+log(O/H) = 7.83+-0.1 and 7.58+-0.1 dex in two HII regions of Cas I, corresponding to Z(gas) of 5-10 times higher than Z(stars) for its stars. The measured Balmer decrements in these HII regions, result in the maximal MW extinction of A_B = 3.06+-0.14 mag in comparison to A_B = 3.69+-0.4 derived via the IR dust emission and is used in other estimates of the distance to Cas I. This reduces the original EDD distance till 4.1 Mpc. The relation of Berg et al. (2012) for the LV late-type galaxies, between 12+log(O/H) and M_B, is used to bracket M_B for Cas I. This, in turn, allows one to get an independent estimate of the distance to Cas~I, of ~1.64~Mpc, albeit with the large 1-sigma uncertainty of factor 2.17. The combination of the above distance estimates, accounting for their uncertainties, results in the probable value of D ~ 3.65 Mpc, what favours Cas I to reside in the environs of IC342.

The hotspot emission of accreting millisecond pulsars (AMPs) undergoes scattering in the accretion flow between the disk inner radius and the neutron star surface. The scattering optical depth of the flow depends on the photon emission angle, which is a function of the pulse phase, and reaches its maximum when the hotspot is closest to the observer. At sufficiently large optical depths the observed pulse profile should develop a secondary minimum, the depth of which depends on the accretion rate and the emission geometry. Such a dip evolving with the accretion rate might explain the phase shift and pulse profile evolution observed in AMPs during outbursts. Accounting for scattering is important for accurate modeling of the AMP pulse profiles in order to improve the accuracy of determination of the neutron star parameters, such as their masses and radii. In this paper we present a simplified analytical model for the Thomson optical depth of the accretion funnel, and apply it to simulating the pulse profiles. We show that scattering in the accretion funnel has a significant effect on the pulse profiles at accretion rates of $\dot{M} \gtrsim 10^{-10}~{M}_\odot\, \mathrm{yr}^{-1}$. Our model predicts a gradual evolution of the pulse profile with the accretion rate that appears to be consistent with the observations.

The Earth's mesopause region between about 75 and 105 km is characterised by chemiluminescent emission from various lines of different molecules and atoms. This emission was and is important for the study of the chemistry and dynamics in this altitude region at nighttime. However, our understanding of molecular emissions with low intensities and high line densities is still very limited. Based on 10 years of data from the astronomical X-shooter echelle spectrograph at Cerro Paranal in Chile, we have characterised in detail this nightglow (pseudo-)continuum in the wavelength range from 300 to 1,800 nm. We studied the spectral features, derived continuum components with similar variability, calculated climatologies, studied the response to solar activity, and even estimated the effective emission heights. The results indicate that the nightglow continuum at Cerro Paranal essentially consists of only two components, which exhibit very different properties. The main structures of these components peak at 595 and 1,510 nm. While the former was previously identified as the main peak of the FeO 'orange arc' bands, the latter is a new discovery. Laboratory data and theory indicate that this feature and other structures between about 800 and at least 1,800 nm are caused by emission from HO$_2$. We performed runs with the Whole Atmosphere Community Climate Model (WACCM) with modified chemistry and found that the total intensity, layer profile, and variability indeed support this interpretation, where the excited HO$_2$ radicals are mostly produced from the termolecular recombination of H and O$_2$. The WACCM results for the continuum at visual wavelengths show good agreement for FeO from the reaction of Fe and O$_3$. However, the simulated total emission appears to be too low, which would require additional mechanisms where the variability is dominated by O$_3$.

We present a study of low surface brightness galaxies (LSBGs) selected by fitting the images for all the galaxies in $\alpha$.40 SDSS DR7 sample with two kinds of single-component models and two kinds of two-component models (disk+bulge): single exponential, single s\'{e}rsic, exponential+deVaucular (exp+deV), and exponential+s\'{e}rsic (exp+ser). Under the criteria of the B band disk central surface brightness $\mu_{\rm 0,disk}{\rm (B) \geqslant 22.5\ mag\ arcsec^{-2}}$ and the axis ratio $\rm b/a > 0.3$, we selected four none-edge-on LSBG samples from each of the models which contain 1105, 1038, 207, and 75 galaxies, respectively. There are 756 galaxies in common between LSBGs selected by exponential and s\'{e}rsic models, corresponding to 68.42% of LSBGs selected by the exponential model and 72.83% of LSBGs selected by the s\'{e}rsic model, the rest of the discrepancy is due to the difference in obtaining $\mu_{0}$ between the exponential and s\'{e}rsic models. Based on the fitting, in the range of $0.5 \leqslant n \leqslant 1.5$, the relation of $\mu_{0}$ from two models can be written as $\mu_{\rm 0,s\acute{e}rsic} - \mu_{\rm 0,exp} = -1.34(n-1)$. The LSBGs selected by disk+bulge models (LSBG_2comps) are more massive than LSBGs selected by single-component models (LSBG_1comp), and also show a larger disk component. Though the bulges in the majority of our LSBG_2comps are not prominent, more than 60% of our LSBG_2comps will not be selected if we adopt a single-component model only. We also identified 31 giant low surface brightness galaxies (gLSBGs) from LSBG_2comps. They are located at the same region in the color-magnitude diagram as other gLSBGs. After we compared different criteria of gLSBGs selection, we find that for gas-rich LSBGs, $M_{\star} > 10^{10}M_{\odot}$ is the best to distinguish between gLSBGs and normal LSBGs with bulge.

Pulsars are known for their exceptionally stable rotation. However, this stability can be disrupted by glitches, sudden increases in rotation frequency whose cause is poorly understood. In this study, we present some preliminary results from the pulsar monitoring campaign conducted at the IAR since 2019. We present measurements from timing solution fits of the parameters of five glitches: one glitch in the Vela pulsar, one in PSR J0742-2822, one in PSR J1740-3015, and two mini-glitches in PSR J1048-5832. Finally, we applied the vortex creep model to characterize the inter-glitch period of Vela. However, the preliminary results yielded highly degenerate and loosely constrained parameters.

Despite a rich observational background, few spectroscopic studies have dealt with the measurement of the carbon isotopic ratio in giant stars. However, it is a key element in understanding the mixing mechanisms that occur in the interiors of giant stars. We present the CNO and $^{12}$C/$^{13}$C abundances derived for 71 giant field stars. Then, using this new catalogue and complementary data from the Kepler and Gaia satellites, we study the efficiency of mixing occurring in the giant branch as a function of the stellar properties. We have determined the abundances of CNO and more specifically 12C/13C using the FIES Spectrograph on the Nordic Optical Telescope, for 71 giant field stars. In addition, asteroseismology is available for all stars, providing their mass, age as well as the evolutionary states. Finally, astrometry from Gaia data is also available for the majority of the sample. We compare these new determinations with stellar evolution models taking into account the effects of transport processes. To exploit the complete potential of our extensive catalogue and considering both the Galactic evolution and the impact of stellar evolution, we built mock catalogues using the Besancon Galaxy model in which stellar evolution models taking into account the effects of thermohaline instability are included. We confirm that 12C/13C at the surface of core He-burning stars is lower than that of first ascent RGB stars. 12C/13C measured at the surface of the core He-burning stars increases with [Fe/H] and mass while it decreases with age. These trends are all very well explained by the thermohaline mixing that occurs in red giants. We have shown that our models can explain the behaviour of 12C/13C versus N/O, although the observations seem to show a lower N/O than the models. We also note that more constraints on the thick disc core He-burning stars are needed to understand this difference.

Gravitational lensing is proven to be one of the most efficient tools for studying the Universe. The spectral confirmation of such sources requires extensive calibration. This paper discusses the spectral extraction technique for the case of multiple source spectra being very near each other. Using the masking technique, we first detect high Signal-to-Noise (S/N) peaks in the CCD spectral image corresponding to the location of the source spectra. This technique computes the cumulative signal using a weighted sum, yielding a reliable approximation for the total counts contributed by each source spectrum. We then proceed with the subtraction of the contaminating spectra. Applying this method, we confirm the nature of 11 lensed quasar candidates.

The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) spacecraft observed the field of the UKIDSS Ultra-Deep Survey (UDS) in August-September 2019, during its flight to Sun-Earth L2 point. The resulting eROSITA UDS (or eUDS) survey was thus the first eROSITA X-ray imaging survey, which demonstrated the capability of the telescope to perform uniform observations of large sky areas. With a moderate single-camera exposure of 150 ks, eUDS covered ~5 deg^2 with the limiting flux ranging between 4E-15 and 5E-14 erg/s/cm^2, in the 0.3-2.3 keV band. We present a catalogue of 647 sources detected at likelihood >10 (~4 sigma) during the eUDS. The catalogue provides information on the source fluxes in the main energy band 0.3-2.3 keV and forced photometry in a number of bands between 0.3 and 8 keV. Using the deeper 4XMM-DR12 catalogue, we have identified 22 strongly variable objects that have brightened or faded by at least a factor of ten during the eROSITA observations compared to previous observations by XMM-Newton. We also provide a catalogue of 22 sources detected by eROSITA in the hard energy band of 2.3-5 keV.

If dark matter is made of QCD axions, its abundance is determined by the vacuum expectation value acquired by the axion field during inflation. The axion is usually assumed to follow the equilibrium distribution arising from quantum diffusion during inflation. This leads to the so-called stochastic window under which the QCD axion can make up all the dark matter. It is characterised by $10^{10.4}\mathrm{GeV}\leq f\leq 10^{17.2}\mathrm{GeV}$ and $H_{\mathrm{end}}>10^{-2.2}\mathrm{GeV}$, where $f$ is the axion decay constant and $H_{\mathrm{end}}$ is the Hubble expansion rate at the end of inflation. However, in realistic inflationary potentials, we show that the axion never reaches the equilibrium distribution at the end of inflation. This is because the relaxation time of the axion is much larger than the typical time scale over which $H$ varies during inflation. As a consequence, the axion acquires a quasi-flat distribution as long as it remains light during inflation. This leads us to reassessing the stochastic axion window, and we find that $ 10^{10.3}\mathrm{GeV}\leq f\leq 10^{14.1}\mathrm{GeV}$ and $H_{\mathrm{end}}>10^{-13.8}\mathrm{GeV}$.

Numerical modeling has long suggested that gravitationally-bound (or so-called rubble-pile) near-Earth asteroids (NEAs) can be destroyed by tidal forces during close and slow encounters with terrestrial planets. However, tidal disruptions of NEAs have never been directly observed nor have they been directly attributed to any families of NEAs. Here we show population-level evidence for the tidal disruption of NEAs during close encounters with the Earth and Venus. Debiased model distributions of NEA orbits and absolute magnitudes based on observations by the Catalina Sky Survey during 2005--2012 underpredict the number of NEAs with perihelion distances coinciding with the semimajor axes of Venus and the Earth. A detailed analysis of the orbital distributions of the excess NEAs shows that their characteristics agree with the prediction for tidal disruptions, and they cannot be explained by observational selection effects or orbital dynamics. Accounting for tidal disruptions in evolutionary models of the NEA population partly bridges the gap between the predicted rate of impacts by asteroids with diameters of tens of meters and observed statistics of fireballs in the same size range.

Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular-momentum transfer in a binary. The faint, stripped companions can be helium-burning subdwarf OB-type stars (sdOBs), white dwarfs (WDs), or neutron stars. We present optical/near-IR CHARA interferometry of 37 Be stars selected for spectroscopic indications of low-mass companions. From multi-epoch $H$- and/or $K$-band interferometry plus radial velocities and parallaxes collected elsewhere, we constructed 3D orbits and derived flux ratios and absolute dynamical masses of both components for six objects, quadrupling the number of anchor points for evolutionary models. In addition, a new wider companion was identified for the known Be + sdO binary 59 Cyg, while auxiliary VLTI/GRAVITY spectrointerferometry confirmed circumstellar matter around the sdO companion to HR 2142. On the other hand, we failed to detect any companion to the six Be stars with $\gamma$ Cas-like X-ray emission, with sdOB and main-sequence companions of the expected spectroscopic mass being ruled out for the X-ray-prototypical stars $\gamma$ Cas and $\pi$ Aqr, leaving the elusive WD companions as the most likely companions, as well as a likely explanation of the X-rays. No low-mass main-sequence close companions were identified in the other stars.

We investigate a cosmological model wherein a waterfall symmetry breaking occurs during the radiation-dominated era. The model comprises a complex waterfall field, an axion field, and the gauge field (dark photon) generated through a tachyonic instability due to the Chern-Simons interaction. Prior to symmetry breaking, the total energy density incorporates a vacuum energy from the waterfall field, establishing a novel scenario for Early Dark Energy (EDE). Subsequent to the symmetry breaking, the dark photon dynamically acquires mass via the Higgs mechanism, potentially contributing to the dark matter abundance. Hence, our model can simultaneously address the $H_0$ tension and the origin of dark matter.

The High-Resolution Multi-Object Spectrograph (HRMOS) is a facility instrument that we plan to propose for the Very Large Telescope (VLT) of the European Southern Observatory (ESO), following the initial presentation at the VLT 2030 workshop held at ESO in June 2019. HRMOS provides a combination of capabilities that are essential to carry out breakthrough science across a broad range of active research areas from stellar astrophysics and exoplanet studies to Galactic and Local Group archaeology. HRMOS fills a gap in capabilities amongst the landscape of future instrumentation planned for the next decade. The key characteristics of HRMOS will be high spectral resolution (R = 60000 - 80000) combined with multi-object (20-100) capabilities and long term stability that will provide excellent radial velocity precision and accuracy (10m/s). Initial designs predict that a SNR~100 will be achievable in about one hour for a star with mag(AB) = 15, while with the same exposure time a SNR~ 30 will be reached for a star with mag(AB) = 17. The combination of high resolution and multiplexing with wavelength coverage extending to relatively blue wavelengths (down to 380\,nm), makes HRMOS a spectrograph that will push the boundaries of our knowledge and that is envisioned as a workhorse instrument in the future. The science cases presented in this White Paper include topics and ideas developed by the Core Science Team with the contributions from the astronomical community, also through the wide participation in the first HRMOS Workshop (https://indico.ict.inaf.it/event/1547/) that took place in Firenze (Italy) in October 2021.

Galaxy clusters are important probes for both cosmology and galaxy formation physics. We test the cosmological, hydrodynamical FLAMINGO simulations by comparing to observations of the gaseous properties of clusters measured from X-ray observations. FLAMINGO contains unprecedented numbers of massive galaxy groups ($>10^6$) and clusters ($>10^5$) and includes variations in both cosmology and galaxy formation physics. We predict the evolution of cluster scaling relations as well as radial profiles of the temperature, density, pressure, entropy, and metallicity for different masses and redshifts. We show that the differences between volume-, and X-ray-weighting of particles in the simulations, and between cool-core non cool-core samples, are similar in size as the differences between simulations for which the stellar and AGN feedback has been calibrated to produce significantly different gas fractions. Compared to thermally-driven AGN feedback, kinetic jet feedback calibrated to produce the same gas fraction at $R_{\rm 500c}$ yields a hotter core with higher entropies and lower densities, which translates into a smaller fraction of cool-core clusters. Stronger feedback, calibrated to produce lower gas fractions and hence lower gas densities, results in higher temperatures, entropies, and metallicities, but lower pressures. The scaling relations and thermodynamic profiles show almost no evolution with respect to self-similar expectations, except for the metallicity decreasing with redshift. We find that the temperature, density, pressure, and entropy profiles of clusters in the fiducial FLAMINGO simulation are in excellent agreement with observations, while the metallicities in the core are too high.

We report the reconstruction of the mass component spectra of cosmic rays (protons, helium, carbon, silicon, and iron) and their mean mass composition, at energies from 1.4 to 100 PeV. The results are derived from the archival data of the extensive air shower experiment KASCADE. We use a novel machine learning technique, developed specifically for this reconstruction, and modern hadronic interaction models: QGSJet.II-04, EPOS-LHC and Sibyll 2.3c. We have found a marked excess of the proton component and deficit of intermediate and heavy nuclei components, compared to the original KASCADE results. At the same time our results are partially consistent with the results of IceTop and TALE experiments. The systematic uncertainties are computed taking into account the difference between the hadronic models and have a similar magnitude as the uncertainties of other mentioned experiments, that were computed without cross-hadronic model systematics.

Young, low-mass Brown Dwarfs orbiting early-type stars, with low mass ratios ($q\lesssim0.01$), appear intrinsically rare and present a formation dilemma: could a handful of these objects be the highest mass outcomes of ``planetary" formation channels (bottom up within a protoplanetary disk), or are they more representative of the lowest mass ``failed binaries" (formed via disk fragmentation, or core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, and when paired with wide wavelength coverage and accurate system age estimates, can constrain evolutionary models in a regime where the models have a wide dispersion depending on initial conditions. We present new interferometric observations of the $16\,\mathrm{Myr}$ substellar companion HD~136164~Ab (HIP~75056~Ab) with VLTI/GRAVITY and an updated orbit fit including proper motion measurements from the Hipparcos-Gaia Catalogue of Accelerations. We estimate a dynamical mass of $35\pm10\,\mathrm{M_J}$ ($q\sim0.02$), making HD~136164~Ab the youngest substellar companion with a dynamical mass estimate. The new mass and newly constrained orbital eccentricity ($e=0.44\pm0.03$) and separation ($22.5\pm1\,\mathrm{au}$) could indicate that the companion formed via the low-mass tail of the Initial Mass Function. Our atmospheric fit to the \texttt{SPHINX} M-dwarf model grid suggests a sub-solar C/O ratio of $0.45$, and $3\times$ solar metallicity, which could indicate formation in the circumstellar disk via disk fragmentation. Either way, the revised mass estimate likely excludes ``bottom-up" formation via core accretion in the circumstellar disk. HD~136164~Ab joins a select group of young substellar objects with dynamical mass estimates; epoch astrometry from future \textit{Gaia} data releases will constrain the dynamical mass of this crucial object further.

The transient sky is composed of diverse phenomena that exhibits dramatic changes on short timescales. These events range from sub-second bursts to weeks and month timescale variability from compact systems. Several challenges need to be addressed by any facility that aims to observe such events: a fast re-positioning scheme to trace the first moments of events like Gamma-Ray Bursts (GRBs), a large field of view to be able to detect new Fast Radio Bursts (FRBs), or high sensitivity and high cadence to detect the outflows and flaring activity in Galactic binaries. Combined with a large bandwidth in order to recover the spectral information from these sources, it would allow us to unveil the physical processes taking place in these systems. The new Multipurpose Interferometer Array (MIA) in Argentina may represent a suitable facility to conduct deep and leading-edge studies on the transient sky as the aforementioned ones. Additionally, there is a significant interest from the community on the possibility of connecting the 30-m IAR antennas within a VLBI network such as the European VLBI Network (EVN). This would place Argentina in the map to achieve very-high-resolution (on the milliarcsecond level) observations. This mode, together with the observations with the MIA would open a potential new regime that would allow astronomers to significantly increase the knowledge on the Southern Sky.

Atmospheric retrievals (AR) characterize exoplanets by estimating atmospheric parameters from observed light spectra, typically by framing the task as a Bayesian inference problem. However, traditional approaches such as nested sampling are computationally expensive, thus sparking an interest in solutions based on machine learning (ML). In this ongoing work, we first explore flow matching posterior estimation (FMPE) as a new ML-based method for AR and find that, in our case, it is more accurate than neural posterior estimation (NPE), but less accurate than nested sampling. We then combine both FMPE and NPE with importance sampling, in which case both methods outperform nested sampling in terms of accuracy and simulation efficiency. Going forward, our analysis suggests that simulation-based inference with likelihood-based importance sampling provides a framework for accurate and efficient AR that may become a valuable tool not only for the analysis of observational data from existing telescopes, but also for the development of new missions and instruments.

The amount of Adaptive Optics (AO) telemetry generated by VIS/NIR ground-based observatories is ever greater, leading to a growing need for a standardised data exchange format to support performance analysis and AO research and development activities that involve large-scale telemetry mining, processing, and curation. This paper introduces the Adaptive Optics Telemetry (AOT) data exchange format as a standard for sharing AO telemetry from visible/infrared ground-based observatories. AOT is based on the Flexible Image Transport System (FITS) and aims to provide unambiguous and consistent data access across various systems and configurations, including natural and single/multiple laser guide-star AO systems. We designed AOT focused on two key use cases: atmospheric turbulence parameter estimation and point-spread function reconstruction (PSF-R). We prototyped and tested the design using existing AO telemetry datasets from multiple systems: single conjugate with natural and laser guide stars, tomographic systems with multi-channel wavefront sensors, single and multi wavefront correctors in systems featuring either a Shack-Hartmann or Pyramid as main wavefront sensors. The AOT file structure has been thoroughly defined, specifying data fields, descriptions, data types, units, and expected dimensions. To support this format, we have developed a Python package that enables data conversion, reading, writing and exploration of AOT files, which has been made publicly available and compatible with a general-purpose Python package manager. We demonstrate the flexibility of the AOT format by packaging data from five different instruments, installed on different telescopes.

Black hole X-ray binaries in their hard and hard-intermediate states display hard and soft time lags between broadband noise variations (high-energy emission lagging low-energy and vice versa), which could be used to constrain the geometry of the disk and Comptonising corona in these systems. Comptonisation and reverberation lag models, which are based on light-travel delays, can imply coronae which are very large (hundreds to thousands of gravitational radii, $R_{g}$) and in conflict with constraints from X-ray spectral modelling and polarimetry. Here we show that the observed large and complex X-ray time lags can be explained by a model where fluctuations are generated in and propagate through the blackbody-emitting disk to a relatively compact ($\sim$10 $R_{g}$) inner corona. The model naturally explains why the disk variations lead coronal variations with a Fourier-frequency dependent lag at frequencies $<1$ Hz, since longer variability time-scales originate from larger disk radii. The propagating fluctuations also modulate successively the coronal seed photons from the disk, heating of the corona via viscous dissipation and the resulting reverberation signal. The interplay of these different effects leads to the observed complex pattern of lag behaviour between disk and power-law emission and different power-law energy bands, the energy-dependence of power-spectral shape and a strong dependence of spectral-timing properties on coronal geometry. The observed spectral-timing complexity is thus a natural consequence of the response of the disk-corona system to mass-accretion fluctuations propagating through the disk.

Objective: In the framework of the Cometary Physics Laboratory (CoPhyLab) and its sublimation experiments of cometary surface analogues under simulated space conditions, we characterize the properties of intimate mixtures of juniper charcoal and SiO$_2$ chosen as a dust analogue \citep{Lethuillier_2022}. We present the details of these investigations for the spectrophotometric properties of the samples. Methods: We measured these properties using a hyperspectral imager and a radio-goniometer. From the samples' spectra, we evaluated reflectance ratios and spectral slopes. From the measured phase curves, we inverted a photometric model for all samples. Complementary characterizations were obtained using a pycnometer, a scanning electron microscope and an organic elemental analyser. Results: We report the first values for the apparent porosity, elemental composition, and VIS-NIR spectrophotometric properties for juniper charcoal, as well as for intimate mixtures of this charcoal with the SiO$_2$. We find that the juniper charcoal drives the spectrophotometric properties of the intimate mixtures and that its strong absorbance is consistent with its elemental composition. We find that SiO$_2$ particles form large and compact agglomerates in every mixture imaged with the electron microscope, and its spectrophotometric properties are affected by such features and their particle-size distribution. We compare our results to the current literature on comets and other small Solar System bodies and find that most of the characterized properties of the dust analogue are comparable to some extent with the spacecraft-visited cometary nucleii, as well as to Centaurs, Trojans and the bluest TNOs.

Massive stars play a major role not only in stellar evolution but also galactic evolution theory. This is because of their dynamical interaction with binary companions, and because their strong winds and explosive deaths as supernovae provide chemical, radiative and kinematic feedback to their environments. Yet this feedback strongly depends on the physics of the supernova progenitor star. It is only in recent decades that asteroseismology - the study of stellar pulsations - has developed the necessary tools to a high level of sophistication to become a prime method at the forefront of astronomical research for constraining the physical processes at work within stellar interiors. For example, precise and accurate asteroseismic constraints on interior rotation, magnetic field strength and geometry, mixing and angular momentum transport processes of massive stars are becoming increasingly available across a wide range of masses. Moreover, ongoing large-scale time-series photometric surveys with space telescopes have revealed a large diversity in the variability of massive stars, including widespread coherent pulsations across a large range in mass and age, and the discovery of ubiquitous stochastic low-frequency (SLF) variability in their light curves. In this invited review, I discuss the progress made in understanding the physical processes at work within massive star interiors thanks to modern asteroseismic techniques, and conclude with a future outlook.

When observing the atmospheres of transiting exoplanets using high-resolution spectroscopy, one aims to detect well-resolved spectral features with high signal-to-noise ratios (SNR) as is possible today with modern spectrographs. However, obtaining such high-quality observations comes with a trade-off: a lower cadence of fewer, longer exposures across the transit collects more photons thanks to reduced overheads, enhancing the SNR of each observation, while a higher cadence of several, shorter exposures minimises spectral feature smearing due to the continuously changing radial velocity of the planet. Considering that maximising SNR and minimising smearing are both beneficial to analysis, there is a need to establish where the optimal compromise lies. In this work, we model real transit events based on targets as they would be observed with VLT/CRIRES+ at Paranal Observatory. Creating four hypothetical scenarios, we simulate each observation across 100 realisations of the same transit event in order to vary the time resolution only. We remove telluric and stellar lines using the SYSREM algorithm and analyse them through cross-correlation with model templates, measuring how successfully each time resolution and case detects the planetary signal. We demonstrate that there is a continuous change in the detection significance based on time resolutions, and that the function of this significance has clear maxima. The strength and location of this maxima varies on e.g. planet system parameters, instrumentation, and no. of removal iterations. We discuss why observers should therefore take several factors into account, using a strategy akin to the 'exposure triangle' from traditional photography where a balance must be struck by considering the full context of the observation. Our method is robust and may be employed by observers to estimate best observational strategies for other targets.

Subhalo dynamics in galaxy cluster host halos govern the observed distribution and properties of cluster member galaxies. We use the IllustrisTNG simulation to investigate the accretion and orbits of subhalos found in cluster-size halos. We find that the median change in the major axis direction of cluster-size host halos is approximately $80$ degrees between $a\sim0.1$ and present-day. We identify coherent regions in the angular distribution of subhalo accretion, and $\sim 68\%$ of accreted subhalos enter their host halo through $\sim38\%$ of the surface area at the virial radius. The majority of galaxy clusters in the sample have $\sim2$ such coherent regions, likely corresponding to cluster-feeding filaments. We further measure angular orbits of subhalos with respect to the host major axis and use a clustering algorithm to identify distinct orbit modes with varying oscillation timescales. The orbit modes correlate with subhalo accretion conditions. Subhalos in orbit modes with shorter oscillations tend to have lower peak masses and accretion directions somewhat more aligned with the major axis. One orbit mode, exhibiting the least oscillatory behavior, largely consists of subhalos that accrete near the plane perpendicular to the host halo major axis. Our findings are consistent with expectations from inflow from major filament structures and internal dynamical friction: most subhalos accrete through filaments, and more massive subhalos experience fewer orbits after accretion. Our work offers a unique quantification of subhalo dynamics that can be connected to how the intracluster medium strips and quenches cluster galaxies.

We present a technique for verifying or refuting exoplanet candidates from the Transiting Exoplanet Survey Satellite (TESS) mission by searching for nearby eclipsing binary stars using higher-resolution archival images from ground-based telescopes. Our new system is called Detecting and Evaluating A Transit: finding its Hidden Source in Time-domain Archival Records (DEATHSTAR). We downloaded time series of cutout images from two ground-based telescope surveys (the Zwicky Transient Facility, or ZTF, and the Asteroid Terrestrial-impact Last Alert System, or ATLAS), analyzed the images to create apertures and measure the brightness of each star in the field, and plotted the resulting light curves using custom routines. Thus far, we have confirmed on-target transits for 17 planet candidates, and identified 35 false positives and located their actual transit sources. With future improvements to automation, DEATHSTAR will be scaleable to run on the majority of TOIs.

The search for sub-GeV dark matter via scattering on electrons has ramped up in the last few years. Like in the case of dark matter scattering on nuclei, electron-recoil-based searches also face an ultimate background in the form of neutrinos. The so-called "neutrino fog'' refers to the range of open dark-matter parameter space where the background of neutrinos can potentially prevent a conclusive discovery claim of a dark matter signal from being made. In this study, we map the neutrino fog for a range of electron recoil experiments based on silicon, germanium, xenon and argon targets. In analogy to the nuclear recoil case, we also calculate the "edge'' to the neutrino fog, which can be used as a visual guide to where neutrinos become an important background -- this boundary excludes some parts of the key theory milestones used to motivate these experiments.

In this paper we entertain a Machian setting where local physics is non-locally affected by the whole Universe, taking the liberty to identify the local (``Newton's bucket'') with our visible Universe, and the whole Universe (Mach's ``fixed stars'') with the global Universe beyond our horizon. Crucially, we allow for the two to have different properties, so that we are beyond the traditional FRW setting. For definiteness we focus on theories where non-locality arises from evolution in the laws of physics in terms of spatially global time variables dual to the constants of Nature. Since non-local theories are foliation-dependent, the {\it local} (but not the global) Hamiltonian constraint is lost. This is true not only while non-locality is taking place, but also after it ceases: the local Hamiltonian constraint is only recovered up to a constant in time, keeping a memory of the integrated past non-locality. We show that this integration constant is equivalent to preserving the local Hamiltonian constraint and adding an extra fluid with the same cosmological properties as conventional pressureless dark matter. The equivalence breaks down in terms of clustering properties, with the new component attracting other matter, but not budging from its location. This is the ultimate ``painted-on'' dark matter, attracting but not being attracted, and nailing down a preferred frame.

In dense astrophysical environments, notably core-collapse supernovae and neutron star mergers, neutrino-neutrino forward scattering can spawn flavor conversion on very short scales. Scattering with the background medium can impact collective flavor conversion in various ways, either damping oscillations or possibly setting off novel collisional flavor instabilities (CFIs). A key feature in this process is the slowness of collisions compared to the much faster dynamics of neutrino-neutrino refraction. Assuming spatial homogeneity, we leverage this hierarchy of scales to simplify the description accounting only for the slow dynamics driven by collisions. We illustrate our new approach both in the case of CFIs and in the case of fast instabilities damped by collisions. In both cases, our strategy provides new equations, the slow-dynamics equations, that simplify the description of flavor conversion and allow us to qualitatively understand the final state of the system after the instability, either collisional or fast, has saturated.

Likelihood-free inference is quickly emerging as a powerful tool to perform fast/effective parameter estimation. We demonstrate a technique of optimizing likelihood-free inference to make it even faster by marginalizing symmetries in a physical problem. In this approach, physical symmetries, for example, time-translation are learned using joint-embedding via self-supervised learning with symmetry data augmentations. Subsequently, parameter inference is performed using a normalizing flow where the embedding network is used to summarize the data before conditioning the parameters. We present this approach on two simple physical problems and we show faster convergence in a smaller number of parameters compared to a normalizing flow that does not use a pre-trained symmetry-informed representation.

We find bounds on the Wilson coefficients of effective field theories (EFTs) living in a Universe undergoing expansion by requiring that its modes do not propagate further than a minimally coupled photon by a resolvable amount. To do so, we compute the spatial shift suffered by the EFT modes at a fixed time slice within the WKB approximation and the regime of validity of the EFT. We analyze the bounds arising on shift-symmetric scalars and curved space generalizations of Galileons.

We explore extensive N-body simulations with two-component cold dark matter candidates. We delve into the temperature evolution, power spectrum, density perturbation, and maximum circular velocity functions. We find that the substantial mass difference between the two candidates and the annihilation of the heavier components to the lighter ones effectively endow the latter with warm dark matter-like behavior, taking advantage of all distinct features that warm dark matter candidates offer, without observational bounds on the warm dark matter mass. Moreover, we demonstrate that the two-component dark matter model aligns well with observational data, providing valuable insights into where and how to search for the elusive dark matter candidates in terrestrial experiments.

We find a new exact solution to Einstein field equations that represents a cosmological wormhole embedded in a flat Friedmann-Lema\^itre-Robertson-Walker universe. The new metric is a generalization of a previous cosmological wormhole solution found by Kim. We explicitly show that the flaring out condition is satisfied at the throat at all cosmic times; in addition, the null energy condition is violated at the throat regardless of the background cosmological model; thus, the spacetime geometry presented here describes a wormhole coupled to the cosmic dynamics that exists at all cosmic times and whose throat remains open in any cosmological model.

With the anticipated launch of space-based gravitational wave detectors, including LISA, TaiJi, TianQin, and DECIGO, expected around 2030, the detection of gravitational waves generated by intermediate-mass black hole binaries (IMBBHs) becomes a tangible prospect. However, due to the detector's reception of a substantial amount of non-Gaussian, non-stationary data, employing traditional Bayesian inference methods for parameter estimation would result in significant resource demands and limitations in the waveform template library. Therefore, in this paper, we simulated foreground noise induced by stellar-origin binary black holes (SOBBHs), which is non-Gaussian and non-stationary, and we explore the use of Gaussian process regression (GPR) and deep learning for parameter estimation of Intermediate Mass Binary Black Holes (IMBBHs) in the presence of such non-Gaussian, non-stationary background noise. By comparing these results from deep learning and GPR, we demonstrate that deep learning can offer improved precision in parameter estimation compared to traditional GPR. Furthermore, compared to GPR, deep learning can provide posterior distributions of the sample parameters faster.

We propose a new method for calculating spectra and luminosities for (anti)neutrinos produced in the pre-supernova environment by weak processes with hot nuclei. It is based on the thermal quasiparticle random phase approximation (TQRPA), that allows microscopic thermodynamically consistent calculations of the weak-interaction response of nuclei at finite temperatures. For realistic representative pre-supernova conditions from the stellar evolution code MESA, we compute (anti)neutrino luminosities and spectra arising from neutral- and charged-current weak reactions with hot $^{56}$Fe and compare them with the contribution of thermal processes. We find that the TQRPA approach produces not only a higher total luminosity of electron neutrinos (mainly born in the electron capture reaction), compared to the standard technique based on the large-scale shell model (LSSM) weak-interaction rates, but also a harder neutrino spectrum. Besides, applying the TQRPA and LSSM, we find that in the context of electron antineutrino generation, the neutral-current nuclear de-excitation (ND) process via neutrino-antineutrino pair emission is at least as important as the electron-positron pair annihilation process. We also show that flavor oscillations enhance the high-energy contribution of the ND process to the electron antineutrino flux. This could potentially be important for pre-supernova antineutrino registration by the Earth's detectors.

Glitches represent a category of non-Gaussian and transient noise that frequently intersects with gravitational wave (GW) signals, exerting a notable impact on the processing of GW data. The inference of GW parameters, crucial for GW astronomy research, is particularly susceptible to such interference. In this study, we pioneer the utilization of normalizing flow for likelihood-free inference of GW parameters, seamlessly integrating the high temporal resolution of the time domain with the frequency separation characteristics of both time and frequency domains. Remarkably, our findings indicate that the accuracy of this inference method is comparable to traditional non-glitch sampling techniques. Furthermore, our approach exhibits greater efficiency, boasting processing times on the order of milliseconds. In conclusion, the application of normalizing flow emerges as pivotal in handling GW signals affected by transient noises, offering a promising avenue for enhancing the field of GW astronomy research.

Air-bearing platforms for simulating the rotational dynamics of satellites require highly precise ground truth systems. Unfortunately, commercial motion capture systems used for this scope are complex and expensive. This paper shows a novel and versatile method to compute the attitude of rotational air-bearing platforms using a monocular camera and sets of fiducial markers. The work proposes a geometry-based iterative algorithm that is significantly more accurate than other literature methods that involve the solution of the Perspective-n-Point problem. Additionally, auto-calibration procedures to perform a preliminary estimation of the system parameters are shown. The developed methodology is deployed onto a Raspberry Pi 4 micro-computer and tested with a set of LED markers. Data obtained with this setup are compared against computer simulations of the same system to understand and validate the attitude estimation performances. Simulation results show expected 1-sigma accuracies in the order of $\sim$ 12 arcsec and $\sim$ 37 arcsec for about- and cross-boresight rotations of the platform, and average latency times of 6 ms.

In certain models of inflation, the postinflationary reheating of the Universe is not primarily due to perturbative decay of the inflaton field into particles, but proceeds through a tachyonic instability. In the process, long-wavelength modes of an unstable field, which is often distinct from the inflaton itself, acquire very large occupation numbers, which are subsequently redistributed into a thermal equilibrium state. We investigate this process numerically through quantum real-time lattice simulations of the Kadanoff-Baym equation, using a 1/N-NLO truncation of the 2PI-effective action. We identify the early-time maximum occupation number, the "classical" momentum range, the validity of the classical approximation and the effective IR temperature, and study the kinetic equilibration of the system and the equation of state.