Search

Context. Strongly lensed quasars are fundamental sources for cosmology. The Gaia space mission covers the entire sky with the unprecedented resolution of 0.18âà € ³ in the optical, making it an ideal instrument to search for gravitational lenses down to the limiting magnitude of 21. Nevertheless, the previous Gaia Data Releases are known to be incomplete for small angular separations such as those expected for most lenses. Aims. We present the Data Processing and Analysis Consortium GravLens pipeline, which was built to analyse all Gaia detections around quasars and to cluster them into sources, thus producing a catalogue of secondary sources around each quasar. We analysed the resulting catalogue to produce scores that indicate source configurations that are compatible with strongly lensed quasars. Methods. GravLens uses the DBSCAN unsupervised clustering algorithm to detect sources around quasars. The resulting catalogue of multiplets is then analysed with several methods to identify potential gravitational lenses. We developed and applied an outlier scoring method, a comparison between the average BP and RP spectra of the components, and we also used an extremely randomised tree algorithm. These methods produce scores to identify the most probable configurations and to establish a list of lens candidates. Results. We analysed the environment of 3 760 032 quasars. A total of 4 760 920 sources, including the quasars, were found within 6âà € ³ of the quasar positions. This list is given in the Gaia archive. In 87% of cases, the quasar remains a single source, and in 501 385 cases neighbouring sources were detected. We propose a list of 381 lensed candidates, of which we identified 49 as the most promising ones. Beyond these candidates, the associate tables in this Focused Product Release allow the entire community to explore the unique Gaia data for strong lensing studies further., 0, info:eu-repo/semantics/published

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We present the results of a search for 10-1000 GeV neutrinos from 2268 gamma-ray bursts (GRBs) over 8 yr of IceCube-DeepCore data. This work probes burst physics below the photosphere where electromagnetic radiation cannot escape. Neutrinos of tens of giga electronvolts are predicted in sub-photospheric collision of free-streaming neutrons with bulk-jet protons. In a first analysis, we searched for the most significant neutrino-GRB coincidence using six overlapping time windows centered on the prompt phase of each GRB. In a second analysis, we conducted a search for a group of GRBs, each individually too weak to be detectable, but potentially significant when combined. No evidence of neutrino emission is found for either analysis. The most significant neutrino coincidence is for Fermi-GBM GRB bn 140807500, with a p-value of 0.097 corrected for all trials. The binomial test used to search for a group of GRBs had a p-value of 0.65 after all trial corrections. The binomial test found a group consisting only of GRB bn 140807500 and no additional GRBs. The neutrino limits of this work complement those obtained by IceCube at tera electronvolt to peta electronvolt energies. We compare our findings for the large set of GRBs as well as GRB 221009A to the sub-photospheric neutron-proton collision model and find that GRB 221009A provides the most constraining limit on baryon loading. For a jet Lorentz factor of 300 (800), the baryon loading on GRB 221009A is lower than 3.85 (2.13) at a 90% confidence level., 0, SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

The IceCube Neutrino Observatory has been continuously taking data to search for O(0.5–10) s long neutrino bursts since 2007. Even if a Galactic core-collapse supernova is optically obscured or collapses to a black hole instead of exploding, it will be detectable via the O(10) MeV neutrino burst emitted during the collapse. We discuss a search for such events covering the time between 2008 April 17 and 2019 December 31. Considering the average data taking and analysis uptime of 91.7% after all selection cuts, this is equivalent to 10.735 yr of continuous data taking. In order to test the most conservative neutrino production scenario, the selection cuts were optimized for a model based on an 8.8 solar mass progenitor collapsing to an O–Ne–Mg core. Conservative assumptions on the effects of neutrino oscillations in the exploding star were made. The final selection cut was set to ensure that the probability to detect such a supernova within the Milky Way exceeds 99%. No such neutrino burst was found in the data after performing a blind analysis. Hence, a 90% C.L. upper limit on the rate of core-collapse supernovae out to distances of ≈25 kpc was determined to be 0.23 yr−1. For the more distant Magellanic Clouds, only high neutrino luminosity supernovae will be detectable by IceCube, unless external information on the burst time is available. We determined a model-independent limit by parameterizing the dependence on the neutrino luminosity and the energy spectrum., 0, SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

Neutrino flares in the sky are searched for in data collected by IceCube between 2011 and 2021 May. This data set contains cascade-like events originating from charged-current electron neutrino and tau neutrino interactions and all-flavor neutral-current interactions. IceCube’s previous all-sky searches for neutrino flares used data sets consisting of track-like events originating from charged-current muon neutrino interactions. The cascade data set is statistically independent of the track data sets, and while inferior in angular resolution, the low-background nature makes it competitive and complementary to previous searches. No statistically significant flare of neutrino emission was observed in an all-sky scan. Upper limits are calculated on neutrino flares of varying duration from 1 hr to 100 days. Furthermore, constraints on the contribution of these flares to the diffuse astrophysical neutrino flux are presented, showing that multiple unresolved transient sources may contribute to the diffuse astrophysical neutrino flux., 0, SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

The pivotal role of nuclear physics in nucleosynthesis processes is being investigated, in particular the intricate influence of photon strength functions (PSFs) and nuclear level densities (NLDs) on shaping the outcomes of the i-, r- and p-processes. Exploring diverse NLD and PSF model combinations uncovers large uncertainties for (p,[Formula: see text]), (n,[Formula: see text]) and ([Formula: see text],[Formula: see text]) rates across many regions of the nuclear chart. These lead to potentially significant abundance variations of the nucleosynthesis processes and highlight the importance of accurate experimental nuclear data. Theoretical insights and advanced experimental techniques lay the ground work for profound understanding that can be gained of nucleosynthesis mechanisms and the origin of the elements. Recent results further underscore the effect of PSF and NLD data and its contribution to understanding abundance distributions and refining knowledge of the intricate nucleosynthesis processes. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'., SCOPUS: ar.j, info:eu-repo/semantics/published

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The IceCube Neutrino Observatory relies on an array of photomultiplier tubes to detect Cherenkov light produced by charged particles in the South Pole ice. IceCube data analyses depend on an in-depth characterization of the glacial ice, and on novel approaches in event reconstruction that utilize fast approximations of photoelectron yields. Here, a more accurate model is derived for event reconstruction that better captures our current knowledge of ice optical properties. When evaluated on a Monte Carlo simulation set, the median angular resolution for in-ice particle showers improves by over a factor of three compared to a reconstruction based on a simplified model of the ice. The most substantial improvement is obtained when including effects of birefringence due to the polycrystalline structure of the ice. When evaluated on data classified as particle showers in the high-energy starting events sample, a significantly improved description of the events is observed., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

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Context. Gravitational waves from black-hole (BH) merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models-And also higher than known stellar-origin black holes in our Galaxy. It has been proposed that those high-mass BHs are the remnants of massive metal-poor stars. Aims. Gaia astrometry is expected to uncover many Galactic wide-binary systems containing dormant BHs, which may not have been detected before. The study of this population will provide new information on the BH-mass distribution in binaries and shed light on their formation mechanisms and progenitors. Methods. As part of the validation efforts in preparation for the fourth Gaia data release (DR4), we analysed the preliminary astrometric binary solutions, obtained by the Gaia Non-Single Star pipeline, to verify their significance and to minimise false-detection rates in high-mass-function orbital solutions. Results. The astrometric binary solution of one source, Gaia BH3, implies the presence of a 32.70a ±a 0.82aM- BH in a binary system with a period of 11.6 yr. Gaia radial velocities independently validate the astrometric orbit. Broad-band photometric and spectroscopic data show that the visible component is an old, very metal-poor giant of the Galactic halo, at a distance of 590 pc. Conclusions. The BH in the Gaia BH3 system is more massive than any other Galactic stellar-origin BH known thus far. The low metallicity of the star companion supports the scenario that metal-poor massive stars are progenitors of the high-mass BHs detected by gravitational-wave telescopes. The Galactic orbit of the system and its metallicity indicate that it might belong to the Sequoia halo substructure. Alternatively, and more plausibly, it could belong to the ED-2 stream, which likely originated from a globular cluster that had been disrupted by the Milky Way., 0, info:eu-repo/semantics/published

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Aims .Over the past decades, libraries of stellar spectra have been used in a large variety of science cases, including as sources of reference spectra for a given object or a given spectral type. Despite the existence of large libraries and the increasing number of projects of large-scale spectral surveys, there is to date only one very high-resolution spectral library offering spectra from a few hundred objects from the southern hemisphere (UVES-POP). We aim to extend the sample, offering a finer coverage of effective temperatures and surface gravity with a uniform collection of spectra obtained in the northern hemisphere. Methods .Between 2010 and 2020, we acquired several thousand echelle spectra of bright stars with the Mercator-HERMES spectrograph located in the Roque de Los Muchachos Observatory in La Palma, whose pipeline offers high-quality data reduction products. We have also developed methods to correct for the instrumental response in order to approach the true shape of the spectral continuum. Additionally, we have devised a normalisation process to provide a homogeneous normalisation of the full spectral range for most of the objects. Results .We present a new spectral library consisting of 3256 spectra covering 2043 stars. It combines high signal-to-noise and high spectral resolution over the entire range of effective temperatures and luminosity classes. The spectra are presented in four versions: raw, corrected from the instrumental response, with and without correction from the atmospheric molecular absorption, and normalised (including the telluric correction)., SCOPUS: ar.j, info:eu-repo/semantics/published

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Context. The physics of stellar rotation plays a crucial role in the evolution of stars, in their final fates, and for the properties of compact remnants. Aims. Diverse approaches have been adopted to incorporate the effects of rotation in stellar evolution models. This study seeks to explore the consequences that these various prescriptions for rotation have for the essential outputs of massive star models. Methods. We computed a grid of 15 and 60 M⊙ stellar evolution models with the Geneva Stellar Evolution Code that accounted for both hydrodynamical and magnetic instabilities induced by rotation. Results. In the 15 and 60 M⊙ models, the choice of the vertical and horizontal diffusion coefficients for the nonmagnetic models strongly impacts the evolution of the chemical structure, but has a weak impact on the angular momentum transport and the rotational velocity of the core. In the 15 M⊙ models, the choice of the diffusion coefficient impacts the convective core size during the core H-burning phase, regardless of whether the model begins core He-burning as a blue or red supergiant and regardless of the core mass at the end of He-burning. In the 60 M⊙ models, the evolution is dominated by mass loss and is less strongly affected by the choice of the diffusion coefficient. In the magnetic models, magnetic instability dominates the angular momentum transport, and these models are found to be less strongly mixed than their rotating nonmagnetic counterparts. Conclusions. Stellar models with the same initial mass, chemical composition, and rotation may exhibit diverse characteristics depending on the physics applied. By conducting thorough comparisons with observational features, we can ascertain which method(s) produce the most accurate results in different cases., SCOPUS: ar.j, info:eu-repo/semantics/published

Neutron stars are remnants of gravitational-core collapse supernovae and provide a uniqueopportunity to explore matter under extreme conditions not reproducible on Earth. In particular,neutron stars are expected to contain nuclear superfluids in their interior. The presence ofsuch phases is supported by observations of pulsar frequency glitches, rapid decline in luminosityof the Cassiopeia A remnant and crust cooling in transiently accreting systems. Nuclearsuperfluidity presents a complex multifluid hydrodynamics. In this work, the influence of temperatureand currents in hot neutron-proton superfluid mixtures is studied within the nuclearenergy-density functional theory. Numerical computations using the Brussels-Montreal functionalsare performed, and the accuracy of several approximations is assessed. The physicalmeaning of the different velocities and momentum densities appearing in superfluid mixturesis clarified. The disappearance of superfluidity is also investigated and reveals the presence of adynamical “gapless" regime. The absence of an energy gap leads to the appearance of a normalfluid of quasiparticle excitations (whose properties are investigated) and also affects considerablythe nucleon specific heat, which is drastically enhanced compared to that obtained in theclassical BCS regime. General approximate analytical formulas for the nucleon specific heat arederived to facilitate their implementation in neutron-star cooling simulations. The implicationsfor the cooling of the crust of transiently accreted neutron stars is discussed. Focusing on twoparticular cases, for which the interpretation of their cooling has been challenged, cooling simulationsare performed accounting for neutron diffusion and allowing for gapless superfluidity.The results suggest that gapless superfluidity plays a key role and reconciles astrophysical observationswith microscopic theories of superfluidity. The various approximations made in thecooling model are discussed as well as, Les étoiles à neutrons sont les vestiges des supernovae par effondrement gravitationnel etoffrent une opportunité unique d’explorer la matière dans des conditions extrêmes impossiblesà reproduire sur Terre. En particulier, les étoiles à neutrons sont supposées contenir dessuperfluides nucléaires dans leur intérieur. La présence de telles phases est corroborée parles observations de soubresauts de fréquence dans les pulsars, une diminution rapide de laluminosité dans le rémanant de Cassiopia A et, un refroidissement de la croûte dans les systèmesaccrétants sporadiquement. La superfluidité nucléaire présente une hydrodynamiquemultifluide complexe. Dans ce travail, l’influence de la température et des courants dans lesmélanges superfluides neutron-proton chauds est étudiée dans le cadre de la théorie de la fonctionnellede densité d’énergie nucléaire. Des calculs numériques utilisant les fonctionnelles deBruxelles-Montréal sont réalisés et la précision de plusieurs approximations est évaluée. La significationphysique des différents champs de vitesses et des densités d’impulsion est clarifiée.La disparition de la superfluidité est également étudiée et révèle la présence d’un régime dynamique“sans gap". L’absence de gap conduit à l’apparition d’un fluide normal d’excitationsde quasi-particules (dont les propriétés sont également étudiées) et affecte également, de façonconsidérable, la chaleur spécifique des nucléons qui est drastiquement augmentée par rapportà celle obtenue dans le régime classique BCS. Des formules analytiques approchées de lachaleur spécifique des nucléons sont dérivées en vue de faciliter leur implémentation dans lessimulations de refroidissement des étoiles à neutrons. Les implications de ce régime pour le refroidissementde la croûte des étoiles à neutrons en accrétion sont discutées. En se concentrantsur deux systèmes particuliers pour lesquels l’interprétation de leur refroidissement est problématique,des simulations de refroidissement sont réalisée, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

Les premières détections d’ondes gravitationnelles émises par la coalescence de trous noirs, et plus récemment par celle d’étoiles à neutrons, ont marqué la naissance d’une nouvelle astronomie. Les interféromètres LIGO et Virgo ont notamment permis de suivre l'évolution d'un couple d'étoiles à neutrons lors des dernières orbites de la phase spiralante, fournissant la première mesure de la déformabilité de marée d'une étoile à neutrons. Dans cette thèse, nous étudions les effets de marée et les oscillations dans les astres compacts incluant non seulement les étoiles à neutrons mais également les naines blanches et des astres plus exotiques contenant un cœur de matière de quarks. Tout d’abord, nous montrons que le second coefficient de déformabilité observable d'une étoile à neutrons est pratiquement insensible à la présence de l'écorce ainsi qu'à la présence d'élasticité dans cette dernière. Le rôle des propriétés de la matière dense sur les coefficients de déformabilité gravito-électriques et gravito-magnétiques d’ordres supérieurs est également étudié. Nous montrons que ces coefficients sont sensibles à la raideur de l’équation d’état de la matière pure de neutrons. En revanche, une variation de l’énergie de symétrie de la matière nucléaire n’affecte pas ces résultats. Les conclusions sont identiques concernant l’impact des effets de marée sur le signal gravitationnel. Ensuite, l’impact de la cristallisation du coeur d'une naine blanche sur sa déformabilité est étudiée en relativité générale. Nous montrons que le cœur solide réduit systématiquement et de façon non-négligeable la déformabilité de l’étoile. Le cas des binaires excentriques de naines blanches est investigué. Dans ce cadre, nous montrons que la non prise en compte de l’élasticité peut induire d’importantes erreurs sur les masses individuelles déduites. Finalement, nous nous intéressons aux naines étranges, astres hypothétiques ressemblant aux naines blanches et possédant un cœur de matière de quarks. D, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

The current interpretation of the observed late time cooling of transiently accreting neutron stars in low-mass x-ray binaries during quiescence requires the suppression of neutron superfluidity in their crust at variance with recent ab initio many-body calculations of dense matter. Focusing on the two emblematic sources KS 1731-260 and MXB 1659-29, we show that their thermal evolution can be naturally explained by considering the existence of a neutron superflow driven by the pinning of quantized vortices. Under such circumstances, we find that the neutron superfluid can be in a gapless state in which the specific heat is dramatically increased compared to that in the classical BCS state assumed so far, thus delaying the thermal relaxation of the crust. We perform neutron-star cooling simulations taking into account gapless superfluidity, and we obtain excellent fits to the data, thus reconciling astrophysical observations with microscopic theories. The imprint of gapless superfluidity on other observable phenomena is briefly discussed., SCOPUS: ar.j, info:eu-repo/semantics/published

If primordial black holes (PBHs) constitute the dark matter (DM), stars forming in dark-matter dominated environments with low velocity dispersions, such as ultra-faint dwarf galaxies, may capture a black hole at birth. The capture probability is non-negligible for PBHs of masses around 10 20 g, and increases with stellar mass. Moreo v er, infected stars are turned into virtually invisible black holes on cosmologically short time-scales. Hence, the number of observed massive main-sequence stars in ultra-faint dwarfs should be suppressed if the DM was made of asteroid-mass PBHs. This would impact the measured mass distribution of stars, making it top-light (i.e. depleted in the high-mass range). Using simulated data that mimic the present-day observational power of telescopes, we show that already existing measurements of the mass function of stars in local ultra-f aint dw arfs could be used to constrain the fraction of DM composed of PBHs in the -currently unconstrained -mass range of 10 19 -10 21 g., SCOPUS: ar.j, info:eu-repo/semantics/published

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Context. It is now well established that the neutron star (NS) merger is at the origin of the production of trans-iron heavy elements in the universe. These elements are therefore present in large quantities in the ejected matter, whose electromagnetic radiation, called kilonova, is characterized by a significant opacity due to the high density of spectral lines belonging to many heavy ions. Among these, the lanthanide ions play an essential role since, with their open 4f subshell, they have a considerable number of transitions that can absorb emitted light. The knowledge of the atomic structure and the radiative parameters of these ions as well as the determination of the corresponding opacities is therefore of paramount importance for the spectral analysis of kilonovae. Aims. The main goal of the present work is to determine the relative contributions of the different lanthanide elements to the opacity of the emission spectrum of a kilonova in its early phase, that is, a few hours after the NS merger, where the conditions are such that the temperature is between 25 000 and 40 000 K. At these temperatures, the lanthanide ions whose charge states are between V and VII are predominant. Methods. We used the pseudo-relativistic Hartree-Fock (HFR) method extensively to calculate the relevant atomic data (energy levels, wavelengths, and oscillator strengths) in La-Lu V-VII ions. The corresponding monochromatic opacities were estimated from the expansion formalism. Results. We calculated the spectroscopic parameters for a total of more than 800 million radiative transitions in all the ions considered. These data were used to estimate the expansion opacities and Planck mean opacities for all the lanthanide elements at early-phase kilonova conditions between 25 000 and 40 000 K, making it possible to deduce the respective contributions of each element as a function of temperature. Atomic calculations were also carried out with the fully relativistic Multiconfiguration Dirac, SCOPUS: ar.j, info:eu-repo/semantics/published

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The interpretation of the thermal evolution of the transiently accreting neutron stars MXB 1659−29 and KS 1731−260 after an outburst is challenging, both within the traditional deep-crustal heating paradigm and the thermodynamically consistent approach of Gusakov and Chugunovthat accounts for neutron diffusion throughout the crust. All these studies assume that the neutron superfluid in the crust is at rest. However, we have recently shown that a finite superflow could exist and could lead to a new gapless superfluid phase if quantized vortices are pinned. We have revisited the cooling of MXB 1659−29 and KS 1731−260 and we have found that gapless superfluidity could naturally explain their late time cooling. We pursue here our investigation by performing new simulations of the thermal relaxation of the crust ofMXB 1659−29 and KS 1731−260 within a Markov Chain Monte Carlo method accounting for neutron diffusion and allowing for gapless superfluidity. We have varied the global structure of the neutron star, the composition of the heat-blanketing envelope, and the mass accretion rate. In all cases, observations are best fitted by models with gapless superfluidity. Finally, we make predictions that could be tested by future observations., SCOPUS: ar.j, info:eu-repo/semantics/published

The sources of ultra-high-energy cosmic rays are still unknown, but assuming standard physics, they are expected to lie within a few hundred megaparsecs from us. Indeed, over cosmological distances cosmic rays lose energy to interactions with background photons, at a rate depending on their mass number and energy and properties of photonuclear interactions and photon backgrounds. The universe is not homogeneous at such scales, hence the distribution of the arrival directions of cosmic rays is expected to reflect the inhomogeneities in the distribution of galaxies; the shorter the energy loss lengths, the stronger the expected anisotropies. Galactic and intergalactic magnetic fields can blur and distort the picture, but the magnitudes of the largest-scale anisotropies, namely the dipole and quadrupole moments, are the most robust to their effects. Measuring them with no bias regardless of any higher-order multipoles is not possible except with full-sky coverage. In this work, we achieve this in three energy ranges (approximately 8–16 EeV, 16–32 EeV, and 32–∞ EeV) by combining surface-detector data collected at the Pierre Auger Observatory until 2020 and at the Telescope Array (TA) until 2019, before the completion of the upgrades of the arrays with new scintillator detectors. We find that the full-sky coverage achieved by combining Auger and TA data reduces the uncertainties on the north-south components of the dipole and quadrupole in half compared to Auger-only results., 0, 37th International Cosmic Ray Conference, ICRC 2021 Virtual, Berlin12 July 2021 through 23 July 2021 Code 177942, info:eu-repo/semantics/published

Context. The Gaia mission of the European Space Agency (ESA) has been routinely observing Solar System objects (SSOs) since the beginning of its operations in August 2014. The Gaia data release three (DR3) includes, for the first time, the mean reflectance spectra of a selected sample of 60 518 SSOs, primarily asteroids, observed between August 5, 2014, and May 28, 2017. Each reflectance spectrum was derived from measurements obtained by means of the Blue and Red photometers (BP/RP), which were binned in 16 discrete wavelength bands. For every spectrum, the DR3 also contains additional information about the data quality for each band. Aims. We describe the processing of the Gaia spectral data of SSOs, explaining both the criteria used to select the subset of asteroid spectra published in Gaia DR3, and the different steps of our internal validation procedures. In order to further assess the quality of Gaia SSO reflectance spectra, we carried out external validation against SSO reflectance spectra obtained from ground-based and space-borne telescopes and available in the literature; we present our validation approach. Methods. For each selected SSO, an epoch reflectance was computed by dividing the calibrated spectrum observed by the BP/RP at each transit on the focal plane by the mean spectrum of a solar analogue. The latter was obtained by averaging the Gaia spectral measurements of a selected sample of stars known to have very similar spectra to that of the Sun. Finally, a mean of the epoch reflectance spectra was calculated in 16 spectral bands for each SSO. Results.Gaia SSO reflectance spectra are in general agreement with those obtained from a ground-based spectroscopic campaign specifically designed to cover the same spectral interval as Gaia and mimic the illumination and observing geometry characterising Gaia SSO observations. In addition, the agreement between Gaia mean reflectance spectra and those available in the literature is good for bright SSOs, regard, 0, info:eu-repo/semantics/published

Diffuse interstellar bands (DIBs) are absorption features seen in optical and infrared spectra of stars and extragalactic objects that are probably caused by large and complex molecules in the galactic interstellar medium (ISM). Here we investigate the Galactic distribution and properties of two DIBs identified in almost six million stellar spectra collected by the Gaia Radial Velocity Spectrometer. These measurements constitute a part of the Gaia Focused Product Release to be made public between the Gaia DR3 and DR4 data releases. In order to isolate the DIB signal from the stellar features in each individual spectrum, we identified a set of 160 000 spectra at high Galactic latitudes (, 0, info:eu-repo/semantics/published

Context. The third Gaia Data Release (DR3) provided photometric time series of more than 2 million long-period variable (LPV) candidates. Anticipating the publication of full radial-velocity data planned with Data Release 4, this Focused Product Release (FPR) provides radial-velocity time series for a selection of LPV candidates with high-quality observations. Aims. We describe the production and content of the Gaia catalog of LPV radial-velocity time series, and the methods used to compute the variability parameters published as part of the Gaia FPR. Methods. Starting from the DR3 catalog of LPV candidates, we applied several filters to construct a sample of sources with high-quality radial-velocity measurements. We modeled their radial-velocity and photometric time series to derive their periods and amplitudes, and further refined the sample by requiring compatibility between the radial-velocity period and at least one of the G, GBP, or GRP photometric periods. Results. The catalog includes radial-velocity time series and variability parameters for 9614 sources in the magnitude range 6 ≲ G/mag ≲ 14, including a flagged top-quality subsample of 6093 stars whose radial-velocity periods are fully compatible with the values derived from the G, GBP, and GRP photometric time series. The radial-velocity time series contain a mean of 24 measurements per source taken unevenly over a duration of about three years. We identify the great majority of the sources (88%) as genuine LPV candidates, with about half of them showing a pulsation period and the other half displaying a long secondary period. The remaining 12% of the catalog consists of candidate ellipsoidal binaries. Quality checks against radial velocities available in the literature show excellent agreement. We provide some illustrative examples and cautionary remarks. Conclusions. The publication of radial-velocity time series for almost ten thousand LPV candidates constitutes, by far, the largest such database avail, 0, info:eu-repo/semantics/published

The Jiangmen Underground Neutrino Observatory (JUNO), the first multi-kton liquid scintillator detector, which is under construction in China, will have a unique potential to perform a real-time measurement of solar neutrinos well below the few MeV threshold typical of Water Cherenkov detectors. JUNO’s large target mass and excellent energy resolution are prerequisites for reaching unprecedented levels of precision. In this paper, we provide estimation of the JUNO sensitivity to 7Be, pep, and CNO solar neutrinos that can be obtained via a spectral analysis above the 0.45 MeV threshold. This study is performed assuming different scenarios of the liquid scintillator radiopurity, ranging from the most optimistic one corresponding to the radiopurity levels obtained by the Borexino experiment, up to the minimum requirements needed to perform the neutrino mass ordering determination with reactor antineutrinos — the main goal of JUNO. Our study shows that in most scenarios, JUNO will be able to improve the current best measurements on 7Be, pep, and CNO solar neutrino fluxes. We also perform a study on the JUNO capability to detect periodical time variations in the solar neutrino flux, such as the day-night modulation induced by neutrino flavor regeneration in Earth, and the modulations induced by temperature changes driven by helioseismic waves., 0, info:eu-repo/semantics/published

We perform an exhaustive follow-up analysis of a subsolar-mass (SSM) gravitational wave (GW) candidate reported by Phukon et al. from the second observing run of Advanced LIGO. This candidate has a reported signal-to-noise ratio (SNR) of 8.6 and false alarm rate of 0.41 yr which are too low to claim a clear gravitational-wave origin. When improving on the search by using more accurate waveforms, extending the frequency range from 45 Hz down to 20 Hz, and removing a prominent blip glitch, we find that the posterior distribution of the network SNR lies mostly below the search value, with the 90% confidence interval being 7.94−1.05+0.70. Assuming that the origin of the signal is a compact binary coalescence (CBC), the secondary component is m2=0.76−0.14+0.50M⊙, with m2<1M⊙ at 84% confidence level, suggesting an unexpectedly light neutron star or a black hole of primordial or exotic origin. The primary mass would be m1=4.71−2.18+1.57M⊙, likely in the hypothesized lower mass gap and the luminosity distance is measured to be DL=124−48+82Mpc. We then probe the CBC origin hypothesis by performing the signal coherence tests, obtaining a log Bayes factor of 4.96±0.13 for the coherent vs. incoherent hypothesis. We demonstrate the capability of performing a parameter estimation follow-up on real data for an SSM candidate with moderate SNR. The improved sensitivity of O4 and subsequent LIGO-Virgo-KAGRA observing runs could make it possible to observe similar signals, if present, with a higher SNR and more precise measurement of the parameters of the binary., SCOPUS: ar.j, info:eu-repo/semantics/published

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The advent of space-based gravitational-wave detectors like the Laser Interferometer Space Antenna will allow to observe signals most of which are expected to be emitted by white-dwarf binaries. Amongthese systems could be hidden another kind of compact objects, postulated by Glendenning, Kettner andWeber in 1995, containing a small core made of strange quark matter surrounded by layers of hadronic matter reaching densities much higher than in white dwarfs. These so called strange dwarfs cannot be easilydistinguished from white dwarfs through electromagnetic observations alone: their outermost envelopes are expected to have the same composition and their radii are quite similar (except for low masses). However, future measurements of the tidal deformability through gravitational-wave observationscould provide a new way to reveal their existence.In this paper, we revisit the structure and the tidal deformability of strange dwarfs in full generalrelativity taking into account the possible crystallization of their envelop. Unlike most previousstudies, we do not describe the hadronic layers using the equation of state of Baym, Pethick and Sutherland, which was originally designed for the outer crust of a neutron star. The conditions leading to such heavy elements in gravitational-core collapse supernova explosions are not expected to be met during the stellar evolution leading to the formation of strange dwarfs. Instead, we consider the same light elements as found in white dwarfs but we take into account electroncaptures by nuclei and possibly pycnonuclear fusions that may be triggered by compression. We find that the radius of strange dwarfs is systematically smaller than that of their white dwarf relatives. These deviations can be large for very low mass stars but mostly lie within the current observational uncertainties for typical white dwarf masses. On the other hand, the observable tidal deformability coefficient $Lambda_2$ is strongly reduced in comparison to wh, info:eu-repo/semantics/published

Space-based gravitational-wave detectors, such as the Laser Interferometer Space Antenna, allow for the probing of the interior of white dwarfs in binaries through the imprints of tidal effects on the gravitational wave signal. In this study, we have computed the tidal deformability of white dwarfs in full general relativity, taking into account the crystallization of their core. The elasticity of the core is found to systematically reduce the tidal deformability, especially for low-mass stars. Moreover, it is shown that errors on the tidal deformability due to the use of the Newtonian theory can become important for massive white dwarfs. Finally, the orbital evolution of eccentric binaries is investigated. Measuring the precession rate of these systems could provide estimations of the individual masses. However, it is found that the neglect of crystallization could lead to very large errors., info:eu-repo/semantics/published

Context. We present the third data release of the European Space Agency's Gaia mission, Gaia DR3. This release includes a large variety of new data products, notably a much expanded radial velocity survey and a very extensive astrophysical characterisation of Gaia sources. Aims. We outline the content and the properties of Gaia DR3, providing an overview of the main improvements in the data processing in comparison with previous data releases (where applicable) and a brief discussion of the limitations of the data in this release. Methods. The Gaia DR3 catalogue is the outcome of the processing of raw data collected with the Gaia instruments during the first 34 months of the mission by the Gaia Data Processing and Analysis Consortium. Results. The Gaia DR3 catalogue contains the same source list, celestial positions, proper motions, parallaxes, and broad band photometry in the G, GBP, and GRP pass-bands already present in the Early Third Data Release, Gaia EDR3. Gaia DR3 introduces an impressive wealth of new data products. More than 33 million objects in the ranges GRVS'<'14 and 3100'<'Teff'<'14'500, have new determinations of their mean radial velocities based on data collected by Gaia. We provide GRVS magnitudes for most sources with radial velocities, and a line broadening parameter is listed for a subset of these. Mean Gaia spectra are made available to the community. The Gaia DR3 catalogue includes about 1 million mean spectra from the radial velocity spectrometer, and about 220 million low-resolution blue and red prism photometer BP/RP mean spectra. The results of the analysis of epoch photometry are provided for some 10 million sources across 24 variability types. Gaia DR3 includes astrophysical parameters and source class probabilities for about 470 million and 1500 million sources, respectively, including stars, galaxies, and quasars. Orbital elements and trend parameters are provided for some 800'000 astrometric, spectroscopic and eclipsing binaries. More, 0, info:eu-repo/semantics/published

info:eu-repo/semantics/published

Context. The recent third data release (DR3) of Gaia has brought some new exciting data about stellar binaries. It provides new opportunities to fully characterize more stellar systems and contributes to enriching our global knowledge of stellar behaviour. Aims. By combining the new Gaia non-single stars catalogue with double-lined spectroscopic binaries (SB2), we can determine the individual masses and luminosities of the components. To fit an empirical mass-luminosity relation in the Gaia G band, lower-mass stars must be added. These masses can be derived using Gaia -resolved wide binaries combined with literature data. Methods. Using the BINARYS tool, we combined the astrometric non-single star solutions in the Gaia DR3 with SB2 data from two other catalogues: the 9th Catalogue of Spectroscopic Binary orbits (SB9), and APOGEE. We also searched for low-mass stars that are resolved in Gaia with direct imaging and H IPPARCOS data or with a literature mass fraction. Results. The combination of Gaia astrometric non-single star solutions with double-lined spectroscopic data enabled us to characterize 43 binary systems with SB9 and 13 systems with APOGEE. We furthermore derived the masses of 6 low-mass binaries that are resolved with Gaia .We then derived an empirical mass-luminosity relation in the Gaia G band down to 0.12 ℳ ⊙ ., SCOPUS: ar.j, info:eu-repo/semantics/published

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In 1995, Glendenning, Kettner, and Weber postulated the existence of some exotic kinds of compact stars resembling white dwarfs (WDs) but containing a very dense core made of strange quark matter. The surrounding layers were described by the same equation of state as for the outer crust of a neutron star. In this work, we revisit the structure of these elusive strange dwarfs (SDs) and compute their tidal deformability in full general relativity using a more realistic model for their crust, taking into account elasticity and different possible compositions. We show that SDs hidden among WD binaries could be potentially unmasked through gravitational-wave observations with future space-based detectors such as LISA., info:eu-repo/semantics/published

info:eu-repo/semantics/published

info:eu-repo/semantics/published

0, info:eu-repo/semantics/published

info:eu-repo/semantics/published