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Probing neutron star interiors and the properties of cold ultra-dense matter with the SKAO
No full textInternational audienceMatter inside neutron stars is compressed to densities several times greater than nuclear saturation density, while maintaining low temperatures and large asymmetries between neutrons and protons. Neutron stars, therefore, provide a unique laboratory for testing physics in environments that cannot be recreated on Earth. To uncover the highly uncertain nature of cold, ultra-dense matter, discovering and monitoring pulsars is essential, and the SKA will play a crucial role in this endeavour. In this paper, we will present the current state-of-the-art in dense matter physics and dense matter superfluidity, and discuss recent advances in measuring global neutron star properties (masses, moments of inertia, and maximum rotation frequencies) as well as non-global observables (pulsar glitches and free precession). We will specifically highlight how radio observations of isolated neutron stars and those in binaries -- such as those performed with the SKA in the near future -- inform our understanding of ultra-dense physics and address in detail how SKAO's telescopes unprecedented sensitivity, large-scale survey and sub-arraying capabilities will enable novel dense matter constraints. We will also address the potential impact of dark matter and modified gravity models on these constraints and emphasise the role of synergies between the SKA and other facilities, specifically X-ray telescopes and next-generation gravitational wave observatories
Search for planetary-mass ultra-compact binaries using data from the first part of the LIGO--Virgo--KAGRA fourth observing run
No full textInternational audienceWe present a search for gravitational waves from inspiraling, planetary-mass ultra-compact binaries using data from the first part of the fourth observing run of LIGO, Virgo and KAGRA. Finding no evidence of such systems, we determine the maximum distance reach for such objects and their merger rate densities, independently of how they could have formed. Then, we identify classes of primordial black-hole mass distributions for which these rate limits can be translated into relevant constraints on the mass distribution of primordial black holes, assuming that they compose all of dark matter, in the mass range . Our constraints are consistent with existing microlensing results in the planetary-mass range, and provide a complementary probe to sub-solar mass objects
The SKAO Pulsar Timing Array
No full textInternational audiencePulsar timing arrays (PTAs) are ensembles of millisecond pulsars observed for years to decades. The primary goal of PTAs is to study gravitational-wave astronomy at nanohertz frequencies, with secondary goals of undertaking other fundamental tests of physics and astronomy. Recently, compelling evidence has emerged in established PTA experiments for the presence of a gravitational-wave background. To accelerate a confident detection of such a signal and then study gravitational-wave emitting sources, it is necessary to observe a larger number of millisecond pulsars to greater timing precision. The SKAO telescopes, which will be a factor of three to four greater in sensitivity compared to any other southern hemisphere facility, are poised to make such an impact. In this chapter, we motivate an SKAO pulsar timing array (SKAO PTA) experiment. We discuss the classes of gravitational waves present in PTA observations and how an SKAO PTA can detect and study them. We then describe the sources that can produce these signals. We discuss the astrophysical noise sources that must be mitigated to undertake the most sensitive searches. We then describe a realistic PTA experiment implemented with the SKA and place it in context alongside other PTA experiments likely ongoing in the 2030s. We describe the techniques necessary to search for gravitational waves in the SKAO PTA and motivate how very long baseline interferometry can improve the sensitivity of an SKAO PTA. The SKAO PTA will provide a view of the Universe complementary to those of the other large facilities of the 2030s
N<sub>2</sub>-broadening coefficients and their temperature exponents for ethylene lines: A semi-empirical approach for (exo)planetary studies
No full textInternational audienceNitrogen-broadening coefficients for ethylene absorption lines in the ν 7 band are computed theoretically to fill in the enormous gaps existing in available experimental data. A semiempirical method relying on the Anderson theory is employed for this purpose, with the model parameters adjusted on some rare room-temperature measurements and used further for calculations in extended temperature ranges. The spectroscopically active molecule C2H4 is rigorously treated as an asymmetric top, and its energy levels and wavefunctions are accurately computed by a quantum-chemistry methodology based on ab initio potential energy surfaces. Theoretical broadening values are obtained for the temperature range 100-1000 K relevant to studies of planetary and exoplanetary atmospheres. These values are further analyzed by the traditional power law to get the associated temperature-dependence exponents. Comparisons of the computed theoretical results with previous measurements and calculations are provided at a low temperature of 173 K to validate the theoretical method chosen. Since the power law describes perfectly the considered temperature range, the sets of reference-temperature broadening coefficients and their temperature exponents can be safely used for higher temperatures where semi-classical approaches applicability only grows. These data are provided for the quantum numbers 0 ≤ J ≤ 47, K ≤ 26 and the three P -, Q-, R-branches of the ν7 band, i.e. represent the most comprehensive up-to-date description of N2-broadened ethylene linewidths suitable for integration into spectroscopic databases and high-temperature simulations of (exo)planetary atmospheres.</div
Advanced digital techniques applied to outcrop models: Integrating Local Binary Pattern (LBP) and Convolutional Neural Network (CNN) to support stratigraphic and sedimentological interpretation of reservoir analogs in the Salta Basin, Argentina
No full textInternational audienc
Exploring the environmental distribution of the oyster parasite Haplosporidium costale
No full textInternational audienceThe protozoan parasite Haplosporidium costale is known to occur in the USA where it has been associated with sharp seasonal mortality of the Eastern oyster Crassostrea virginica since the 1960’s. In 2019, the parasite was detected for the first time in the Pacific oyster Magallana gigas in France in the context of light mortality and was subsequently detected in archived material collected since 2008. This detection raised several questions regarding the ability of the parasite to maintain in the ecosystem and the potential involvement of other species in its life cycle. To answer these questions, an integrated sampling approach was deployed seasonally in three oyster farming areas where the parasite was already known to occur. Parasite presence was evaluated after checking the presence of PCR inhibitors and using a previously developed and validated Real Time PCR assay, optimized in this study to detect parasite DNA in various environmental compartments. Parasite DNA was almost only detected in cupped oysters. Considering the high number of oysters found positive with low infection intensity, a complementary experiment was undertaken to better characterize sub-clinical infections in oysters. The presence of the parasite was tested twice a week in water and sediment from aquaria hosting cupped oysters from a known infected site. After one month, oysters were sacrificed and tested regarding the presence of the parasite at the tissular level. Altogether, field and experimental results indicate that the parasite is stably established in oyster, particularly in gills, which may act as a reservoir all along the year. The detection of parasite DNA in nanoplankton and sediment suggests that H. costale is released from the oysters outside mortality event. Our results do not support the involvement of other species than cupped oyster in the parasite life cycle except periwinkles, whose role would deserve to be further investigate
Northernmost record in the Bay of Biscay (northeastern Atlantic) of two leptothecate hydroids (Cnidaria: Hydrozoa) of southern affinity
No full textInternational audienceTwo leptothecate hydroids of southern affinity, Sertularella ornata Broch, 1933 and Sertularelloides cylindritheca (Allman, 1888) were collected in the southern sector of the Bay of Biscay off Saint Jean de Luz (France). The latter was also seen during several ROV surveys on rocky communities along the Cantabrian Sea and northwestern Spain. Each of the two species is herein described and illustrated and their worldwide distribution, bathymetric ranges and reproductive periods, revised; additionally, we allocate them in their biocoenological context, providing in situ images. The northern boundary limits are extended for both hydroids, which are new records for the Atlantic coast of France; the latter belongs to a genus previously unrecorded in the French mainland fauna. We also discuss the importance of having inventories of the sessile fauna of the exceptional sites at study, for the sake of their protection and detection of future modifications due to climate change
4MOST Cosmology Redshift Survey (CRS): Clustering properties of CRS BG and LRG target catalogues
No full textInternational audienceThe 4MOST Cosmology Redshift Survey (CRS) will obtain nearly 5.4 million spectroscopic redshifts over deg to map large-scale structure and enable measurements of baryon acoustic oscillations (BAOs), growth rates via redshift-space distortions, and cross-correlations with weak-lensing surveys. We validate the target selections, photometry, masking, systematics and redshift distributions of the CRS Bright Galaxy (BG) and Luminous Red Galaxy (LRG) target catalogues selected from DESI Legacy Surveys DR10.1 imaging. We measure the angular two-point correlation function, test masking strategies, and recover redshift distributions via cross-correlation with DESI DR1 spectroscopy. For BG, we adopt Legacy Survey \texttt{MASKBITS} that veto bright stars, SGA large galaxies, and globular clusters; for LRG, we pair these with an unWISE W1 artefact mask. These choices suppress small-scale excess power without imprinting large-scale modes. A Limber-scaling test across BG -band magnitude slices shows that, after applying the scaling, the curves collapse to a near-common power law over the fitted angular range, demonstrating photometric uniformity with depth and consistency between the North (NGC) and South (SGC) Galactic Caps. Cross-correlations with DESI spectroscopy recover the expected , with higher shot noise at the brightest magnitudes. For LRGs, angular clustering in photo- slices () is mutually consistent between the DECaLS and DES footprints at fixed and is well described by an approximate power law once photo- smearing is accounted for; halo-occupation fits yield results consistent with recent LRG studies. Together, these tests indicate that the masks and target selections yield uniform clustering statistics, supporting precision large-scale structure analyses with 4MOST CRS
Strain pattern and active faults' compatibility across the Western Alps revealed by 25 years of GNSS measurements
No full textUpdated GNSS solutions integrating 25 years of GNSS data allow to evaluate deformation rates of 0.1–1 mm/yr in the WesternAlps, and in particular to compare the High Durance fault (HDF) activity (internal zones) with the Belledonne Fault (BDF)(external zone). Strain rate estimates are larger across HDF (19 ± 3 nanostrain/yr EW extension) than BDF (5 ± 1 nanostrain/yr EW compression). Fault slip rates indicate dominant dextral strike-slip motion on BDF (0.2 ± 0.1 mm/yr), whileHDF exhibits major extensional motion (0.3 ± 0.1 mm/yr). These two faults represent therefore the broader kinematics of theW-Alps characterized by seismicity showing mainly extensional deformation in the internal zones (HDF) and strike-slip motionin the external zone (BDF). Finally, a rigid 3-blocks model explains 29% of the observed GNSS velocity field and confirms theHDF and BDF deformation styles and their interconnected roles in the W-Alpine deformation framework
Born to be recycled: a comprehensive population synthesis of the Galactic millisecond pulsars
No full textInternational audienceMillisecond pulsars (MSPs) are the oldest but fastest pulsars known to date. To explain how these pulsars could be formed, a new hypothesis was formulated: the recycling of pulsars, i.e the fact that a pulsar could accrete matter from a companion and been spun up. In this paper, we developed a population synthesis algorithm for pulsars which belong to a binary, in order to check whether most of the observed recycled pulsars were formed via an accretion mechanism and derive statistics about their properties, that are difficult to obtain through observations. We also make predictions for future surveys. Toward the presented objectives, we use the code Stellar EVolution for N-body (SEVN) to take into account all the binary processes and our own code to evolve each pulsar self-consistently by taking into account the secular evolution of a force-free magnetosphere, the magnetic field decay, gravitational braking and spatial evolution. Each pulsar is born in binary with a main sequence companion, and evolve to present time. The radio and -ray emission locations were modeled by the polar cap geometry and striped wind model, respectively. Our simulations seem to reproduce well the population of radio and -ray pulsars observed in the selected surveys. We also found that there should be less than unidentified pulsars in the Fourth Fermi-LAT catalogue of -ray sources (4FGL). High values of the viewing angle seem to be needed to be able to observe the recycled pulsars, and it also seems difficult to observe recycled pulsars with an aligned rotation axis and magnetic axis (i.e., °). We find that only a small fraction, approximately %, of oxygen-neon white dwarfs (ONeWDs) in binary systems appear to contribute to the population of mildly recycled pulsars through accretion-induced collapse