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Deimos photometric properties from Mars Express HRSC/SRC observations
No full textInternational audienceFor more than 21 years, the Mars Express mission (MEx) has been orbiting the Martian system, acquiring data on Mars' surface and atmosphere, as well as on its two moons, Phobos and Deimos. The origin of the Martian moons remains a matter of debate. Deimos is the smallest of the two moons and orbits Mars at a much greater distance than Phobos. Previous photometric analyses [1] show that the surface of Deimos is smoother and more homogeneous than that of Phobos, but with overall similar photometric properties.We analyzed images of Deimos taken with both the High Resolution Stereo Camera (HRSC) and the Super Resolution Channel (SRC) instruments. HRSC is a pushbroom camera with nine filters, including five panchromatic and four color filters (blue, green, red, and infrared), while the SRC is a framing camera with one panchromatic filter centered at 650 nm and covering from 400 to 900 nm [2,3]. The HRSC Deimos dataset is relatively limited with only 18 images available in each filter, acquired between January 2018 and January 2025, with a spatial resolution ranging from 390 m/px to 800 m/px. Conversely, the SRC dataset of Deimos contains more than 3500 images covering more than 20 years of observations, from October 2004 to December 2024. The spatial resolution varies from 85 m/px to 300 m/px, while the phase angle ranges from 0.06 to 120°. For the very first time, we have calibrated the absolute response of SRC using images of stars and Jupiter. We performed both disk-integrated and disk-resolved photometry. From the retrieved phase curve, we applied the Hapke IMSA [4] model to characterize the physical properties and the texture of the surface
Modelling Martian moons’ surface temperature: Surface temperature variations and surface thermal emission removal from future MMX/MIRS data
No full textInternational audienceThe mission Martian Moons eXploration (MMX) from the Japanese space exploration agency (JAXA) will study the Martian system for three years starting from 2027. The spectro-imager MMX InfraRed Spectrometer (MIRS) will observe the surface of Phobos and Deimos in the near-infrared between 0.9 and 3.6 μm. At the surface of the Martian moons, thermal emission starts to contribute around 2.5 μm and will modify the future MIRS radiance measurements.Aims. We propose a physical method to remove the surface thermal emission contribution from the future measured spectra from MIRS data.Methods. The method simulates the moons’ surface temperatures locally and computes their thermal emission accounting for ephemerides and topography. We therefore developed a simulation of the absorbed flux at the moons’ surface that allows their sub-surface temperature to be computed using a 1D thermal model. We used this to estimate the emitted thermal flux in the near-infrared domain.Results. We computed the surface temperature on the complete surface of Phobos at a lateral resolution of 3° × 3°. We found that surface temperatures on Phobos vary in the range [100, 320] K depending on the thermal and textural properties of the surface, in good agreement with previous estimations. Our results indicate that the reflected solar illumination and thermal emission from Mars increase the annual average temperature of the sub-Mars hemisphere on Phobos by 7 K. This underscores the importance of accounting for the Mars effect when modelling the thermal tail observed by MIRS. We tested the sensitivity of the method to the presence of absorption features in the spectrum and found that the method is stable as long as the absorptions are located before the thermal emission range
Primordial black holes and their gravitational-wave signatures
No full textInternational audienceIn the recent years, primordial black holes (PBHs) have emerged as one of the most interesting and hotly debated topics in cosmology. Among other possibilities, PBHs could explain both some of the signals from binary black hole mergers observed in gravitational wave detectors and an important component of the dark matter in the Universe. Significant progress has been achieved both on the theory side and from the point of view of observations, including new models and more accurate calculations of PBH formation, evolution, clustering, merger rates, as well as new astrophysical and cosmological probes. In this work, we review, analyse and combine the latest developments in order to perform end-to-end calculations of the various gravitational wave signatures of PBHs. Different ways to distinguish PBHs from stellar black holes are emphasized. Finally, we discuss their detectability with LISA, the first planned gravitational-wave observatory in space
Anti-de Sitterian "massive" elementary systems and their Minkowskian and Newtonian limits
No full textInternational audienceWe elaborate the definition and properties of ''massive" elementary systems in the (1+3)-dimensional Anti-de Sitter (AdS) spacetime, on both classical and quantum levels. We fully exploit the symmetry group Sp, that is, the two-fold covering of SO (Sp SO), recognized as the relativity/kinematical group of motions in AdS spacetime. In particular, we discuss that the group coset Sp/S(U(1)x SU(2)), as one of the Cartan classical domains, can be interpreted as a phase space for the set of free motions of a test massive particle on AdS spacetime; technically, in order to facilitate the computations, the whole process is carried out in terms of complex quaternions. The (projective) unitary irreducible representations (UIRs) of the Sp group, describing the quantum version of such motions, are found in the discrete series of the Sp UIRs. We also describe the null-curvature (Poincaré) and non-relativistic (Newton-Hooke) contraction limits of such systems, on both classical and quantum levels. On this basis, we unveil the dual nature of ''massive" elementary systems living in AdS spacetime, as each being a combination of a Minkowskian-like massive elementary system with an isotropic harmonic oscillator arising from the AdS curvature and viewed as a Newton-Hooke elementary system. This matter-vibration duality will take its whole importance in the quantum regime (in the context of the validity of the equipartition theorem) in view of its possible rôle in the explanation of the current existence of dark matter
Phases and Phase transitions of U(1)SU(2) symmetric holographic matter
No full textInternational audienceThe phase diagram and symmetry breaking patterns of a holographic CFT with U(1)SU(2) symmetry are analyzed using the simplest holographic action, namely Einstein-Yang-Mills (YM) theory with a negative cosmological constant. This is relevant for both condensed matter and QCD applications. With a U(1) and an "isospin" chemical potential turned on, we determine all possible symmetry breaking patterns, which are associated to the condensation of spin-one order parameters. The possible IR asymptotics of the Einstein-YM solutions are derived analytically, both for 2+1 and 3+1 boundary dimensions. The competing solutions are then computed numerically, both at zero and non-zero temperature, from which the full three-dimensional phase diagram is determined. We find a surface of second order phase transitions that separate uncondensed and condensed phases. In some regions with a large fraction of charged to neutral degrees of freedom, the phase transition becomes first order
Swift-BAT GUANO follow-up of gravitational-wave triggers in the third LIGO-Virgo-KAGRA observing run
No full textInternational audienceWe present results from a search for X-ray/gamma-ray counterparts of gravitational-wave (GW) candidates from the third observing run (O3) of the LIGO-Virgo-KAGRA (LVK) network using the Swift Burst Alert Telescope (Swift-BAT). The search includes 636 GW candidates received in low latency, 86 of which have been confirmed by the offline analysis and included in the third cumulative Gravitational-Wave Transient Catalogs (GWTC-3). Targeted searches were carried out on the entire GW sample using the maximum--likelihood NITRATES pipeline on the BAT data made available via the GUANO infrastructure. We do not detect any significant electromagnetic emission that is temporally and spatially coincident with any of the GW candidates. We report flux upper limits in the 15-350 keV band as a function of sky position for all the catalog candidates. For GW candidates where the Swift-BAT false alarm rate is less than 10 Hz, we compute the GW--BAT joint false alarm rate. Finally, the derived Swift-BAT upper limits are used to infer constraints on the putative electromagnetic emission associated with binary black hole mergers
Euclid preparation LXI. Cosmic Dawn Survey: ‘Pre-launch’ multiwavelength catalogues for Euclid Deep Field North and Euclid Deep Field Fornax
No full textInternational audienceThe Cosmic Dawn Survey (DAWN survey) provides multiwavelength (UV/optical to mid-IR) data across the combined 59 deg of the Euclid Deep and Auxiliary fields (EDFs and EAFs). Here, the first public data release (DR1) from the DAWN survey is presented. DR1 catalogues are made available for a subset of the full DAWN survey that consists of two Euclid Deep fields: Euclid Deep Field North (EDF-N) and Euclid Deep Field Fornax (EDF-F). The DAWN survey DR1 catalogues do not include data as they are not yet public for these fields. Nonetheless, each field has been covered by the ongoing Hawaii Twenty Square Degree Survey (H20), which includes imaging from CFHT MegaCam in the new filter and from Subaru Hyper Suprime-Cam (HSC) in the filters. Each field is further covered by /IRAC 3.6-4.5m imaging spanning 10 deg and reaching 25 mag AB (5). All present H20 imaging and all publicly available imaging from the aforementioned facilities are combined with the deep /IRAC data to create source catalogues spanning a total area of 16.87 deg in EDF-N and 2.85 deg in EDF-F for this first release. Photometry is measured using The Farmer, a well-validated model-based photometry code. Photometric redshifts and stellar masses are computed using two independent codes for modeling spectral energy distributions: EAZY and LePhare. Photometric redshifts show good agreement with spectroscopic redshifts (\sigma_{\rm NMAD} \sim 0.5, \eta < 8\% at i < 25). Number counts, photometric redshifts, and stellar masses are further validated in comparison to the COSMOS2020 catalogue. The DAWN survey DR1 catalogues are designed to be of immediate use in these two EDFs and will be continuously updated. Future data releases will provide catalogues of all EDFs and EAFs and include data
The track-length extension fitting algorithm for energy measurement of interacting particles in liquid argon TPCs and its performance with ProtoDUNE-SP data
No full textInternational audienceThis paper introduces the hypothetical track-length fitting algorithm, a novel method for measuring the kinetic energies of ionizing particles in liquid argon time projection chambers (LArTPCs). The algorithm finds the most probable offset in track length for a track-like object by comparing the measured ionization density as a function of position with a theoretical prediction of the energy loss as a function of the energy, including models of electron recombination and detector response. The algorithm can be used to measure the energies of particles that interact before they stop, such as charged pions that are absorbed by argon nuclei. The algorithm's energy measurement resolutions and fractional biases are presented as functions of particle kinetic energy and number of track hits using samples of stopping secondary charged pions in data collected by the ProtoDUNE-SP detector, and also in a detailed simulation. Additional studies describe impact of the dE/dx model on energy measurement performance. The method described in this paper to characterize the energy measurement performance can be repeated in any LArTPC experiment using stopping secondary charged pions
Euclid preparation. The impact of relativistic redshift-space distortions on two-point clustering statistics from the Euclid wide spectroscopic survey
No full textInternational audienceMeasurements of galaxy clustering are affected by RSD. Peculiar velocities, gravitational lensing, and other light-cone projection effects modify the observed redshifts, fluxes, and sky positions of distant light sources. We determine which of these effects leave a detectable imprint on several 2-point clustering statistics extracted from the EWSS on large scales. We generate 140 mock galaxy catalogues with the survey geometry and selection function of the EWSS and make use of the LIGER method to account for a variable number of relativistic RSD to linear order in the cosmological perturbations. We estimate different 2-point clustering statistics from the mocks and use the likelihood-ratio test to calculate the statistical significance with which the EWSS could reject the null hypothesis that certain relativistic projection effects can be neglected in the theoretical models. We find that the combined effects of lensing magnification and convergence imprint characteristic signatures on several clustering observables. Their S/N ranges between 2.5 and 6 (depending on the adopted summary statistic) for the highest-redshift galaxies in the EWSS. The corresponding feature due to the peculiar velocity of the Sun is measured with a S/N of order one or two. The from the catalogues that include all relativistic effects reject the null hypothesis that RSD are only generated by the variation of the peculiar velocity along the line of sight with a significance of 2.9 standard deviations. As a byproduct of our study, we demonstrate that the mixing-matrix formalism to model finite-volume effects in the can be robustly applied to surveys made of several disconnected patches. Our results indicate that relativistic RSD, the contribution from weak gravitational lensing in particular, cannot be disregarded when modelling 2-point clustering statistics extracted from the EWSS
Derivation of a 4-moment model for electron transport in Hall thrusters from a gyrokinetic model
No full textWe model the motion of a population of electrons in a strong electromagnetic field undergoing elastic electron/electron collisions. This regime is derived from a dimensional analysis of the electron confinement in Hall-effect thrusters. The electrons exhibit a very high cyclotron frequency and a E × B-drift, modelled by stiff PDEs at the mesoscopic scale. We obtain a gyrokinetic model in which the fastest oscillations of the system are filtered out by averaging the rotation of the electrons around the magnetic field lines. The model is derived in the strong electromagnetic field limit. Based on this gyrokinetic model, we then develop a 10-moment model. The averaging operation performed at the kinetic scale leads to symmetry properties that allow to reduce the 10-moment model to a 4-moment model.</div