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Euclid: Quick Data Release (Q1) – Watching ICM-selected galaxy clusters with Euclid eyes - prospects of Euclid data in the context of large SZ and X-ray based surveys
No full textInternational audienceGalaxy clusters detected through their X-ray emission or Sunyaev--Zeldovich effect (SZE), both produced by the intra-cluster medium (ICM), are key probes in cosmological and astrophysical studies. To maximise the scientific return of such surveys, complementary data are required for cluster confirmation and redshift estimation. This is typically provided by wide-field optical and infrared surveys, which are increasingly challenged by ongoing and future ICM-selected samples. In particular, at high redshifts () probed by upcoming SZE-selected samples, current large surveys may be insufficient for reliable confirmation. Deep, high-resolution infrared surveys like Euclid will thus be essential for confirming most high-redshift clusters. We present an analysis of the first sizeable Euclid dataset (Q1), overlapping with several ICM-selected cluster samples. We apply an adaptation of the MCMF cluster confirmation tool to estimate key properties, including redshift and richness, and to predict Euclid's capabilities for high-redshift cluster confirmation. We find promising performance, particularly at high redshifts, while richness estimates at low redshifts () are currently limited by Q1 data quality but should improve with future releases. Using MCMF runs on random lines of sight, we predict that Euclid will confirm clusters at as effectively as current optical surveys at , significantly enhancing high-redshift confirmation. SZE-selected samples will thus greatly benefit from Euclid overlap. Among five known high- SZE clusters in Q1, we identify the highest-redshift jellyfish galaxy candidate to date, EUCLJ035330.86504347.6 in SPT-CLJ03535043 (), two massive star-forming galaxies near ACT-CLJ0350.04819 (), and strong lensing features in SPT-CLJ03535043 and SPT-CLJ04214845
Evolution of Solar Wind Turbulence during Radial Alignment of Parker Solar Probe and Solar Orbiter in 2022 December
No full textInternational audienceAbstract We investigate the radial evolution of solar wind turbulence during the radial alignment of Parker Solar Probe (PSP) and Solar Orbiter (SO) on 2022 December 10, with PSP located at approximately 0.11 au and SO near 0.88 au. To identify nearly the same plasma parcel crossing both spacecraft, we apply a ballistic propagation model with time-constant acceleration constrained by in situ solar wind velocity measurements at PSP and SO. We trace the magnetic footpoint of the plasma parcel back to the photosphere using a potential field source surface model based on a Global Oscillations Network Group synoptic magnetogram. Field and plasma measurements from PSP and SO are used to analyze power spectral density (PSD), spectral scaling, magnetic compressibility, and intermittency. Our results show that (1) the trace PSD of magnetic fluctuations steepens in the inertial range and flattens in the dissipation range with increasing radial distance; (2) the spectral break shifts to lower frequencies at SO; and (3) the Castaing model reveals multifractal intermittency in the inertial range, with slightly weaker intermittency at SO. These findings based on the same plasma parcel are consistent with the results of statistical studies on the radial evolution of turbulence and provide a reference for theoretical modeling of turbulence in the inner heliosphere
Status of the PAIPS Project and Selected Results
No full textInternational audiencePulsating aurora (PsA) and UV microbursts are studied, and examples are given of using probabilistic models based on Bayesian inference to reconstruct track events. The operation of the aurora altitude determination algorithm is demonstrated using one event as an example in analyzing PsAs. A database of UV microbursts (series of short flashes) for two seasons of the experiment (2021/2022 and 2022/2023) is obtained and analyzed
The Modeling Landscape of Extragalactic CO in CMB Surveys
No full textInternational audienceExtragalactic carbon monoxide (CO) line emission will likely be an important signal in current and future Cosmic Microwave Background (CMB) surveys on small scales. However, great uncertainty surrounds our current understanding of CO emission. We investigate the implications of this modeling uncertainty on CMB surveys. Using a range of star formation rate and luminosity relations, we generate a suite of CO simulations across cosmic time, together with the broadband cosmic infrared background (CIB). From these, we quantify the power spectrum signatures of CO that we would observe in a CMB experiment at 90, 150, and 220 GHz. We find that the resulting range of CO auto-spectra spans up to two orders of magnitude and that while CO on its own is unlikely to be detectable in current CMB experiments, its cross-correlation with the CIB will be a significant CMB foreground in future surveys. We then forecast the bias on CMB foregrounds that would result if CO were neglected in a CMB power spectrum analysis, finding shifts that can be comparable to some of the uncertainties on CMB foreground constraints from recent surveys, particularly for the thermal and kinetic Sunyaev-Zel'dovich effects and radio sources, and many times greater than the expected uncertainties expected for future data. Finally, we assess how the broad range of multifrequency COCIB spectra we obtain is captured by a reduced parameter set by performing a principal component analysis, finding that three amplitude parameters suffice for a CMB-S4-like survey. Our results demonstrate the importance for future CMB experiments to account for a wide range of CO modeling, and that high-precision CMB experiments may help constrain extragalactic CO models
Modèle statistique apprenable de mélange de distributions et fusion de données multivariées pour l'imagerie d'exoplanètes
No full textInternational audienceExoplanet imaging is a major challenge in astrophysics due to the high star-planet contrast. This paper presents a multi-scale statistical model for the nuisance component corrupting multivariate image series. Integrated into a learnable architecture, it leverages the physics of the problem and enables the fusion of multiple observations of the same star. Applied to real data, the method significantly improves the detection sensitivity and the accuracy of exoplanet position and flux estimation.L'imagerie des exoplanètes est un défi majeur en raison du fort contraste étoile-planète. Cet article propose un modèle statistique multi-échelle de la nuisance affectant des séries d’images multivariées. Intégré à une architecture apprenable, il exploite la physique du problème et permet la fusion de plusieurs observations d’une même étoile. Appliquée à des données réelles, la méthode améliore significativement la sensibilité de détection et la précision de l’estimation de la position et du flux des exoplanètes
Catalog of very-high-energy emitting active galactic nuclei at high Galactic latitudes
No full textInternational audienceLarge number of Active Galactic Nuclei (AGN) producing Very-High-Energy (VHE) gamma-rays (energies above 100~GeV) has been revealed using observations with Imaging Atmospheric Cherenkov Telescopes (IACTs). However, our knowledge of the VHE emitting AGN population is limited in the absence of an unbiased sky survey. We use long exposure of Fermi Large Area Telescope (LAT) to perform a survey of VHE emitting AGN at Galactic latitudes |b|>10 degrees. We consider clustering of gamma-ray events with energies E>100 GeV around positions of AGN from the 4-th LAT source catalog to select sources detected in the VHE range. The VHE AGN catalog produced in this way contains overall 175 sources detected with high confidence and additional 100 sources detected at more than 3-sigma level. It is 90% complete at the flux limit 1.3e-12 erg/cm2s. Less than half of the source sample (71) are previously reported VHE emitters, other sources are new detections in the VHE band. The majority of VHE AGN detectable at the survey flux limit are BL Lac type objects. We find their luminosity function to derive their spatial density (6.5+/-0.5)e-7/ Mpc3 and the characteristic luminosity scale ~1e44 erg/s. Ten sources in the VHE AGN catalog are nearby radio galaxies and seven are flat spectrum radio quasars, while 20 sources are unclassified AGN. We also include in our catalog four unidentified sources that may or may not be VHE AGN. 63 source in the catalog are "extreme" blazars, with 41 of them being new VHE band detections. In spite of the fact that the VHE flux is heavily attenuated by the pair production in interactions with Extragalactic Background Light (EBL), the catalog includes 7 sources at redshift larger than 1. Some of these sources show peculiar hardening of the VHE band spectra that point either to errors in redshift determination, or to limitations of modeling of cosmological evolution of EBL
Euclid preparation: The NISP spectroscopy channel, on ground performance and calibration
No full textInternational audienceESA's Euclid cosmology mission relies on the very sensitive and accurately calibrated spectroscopy channel of the Near-Infrared Spectrometer and Photometer (NISP). With three operational grisms in two wavelength intervals, NISP provides diffraction-limited slitless spectroscopy over a field of deg. A blue grism covers the wavelength range -- nm at a spectral resolution -- for a diameter source with a dispersion of nm px. Two red grisms span to nm at -- and a dispersion of nm px. We describe the construction of the grisms as well as the ground testing of the flight model of the NISP instrument where these properties were established
Detectability of the daily evapotranspiration cycle in superconducting gravimeter timeseries according to the measurement configuration
No full textInternational audienceEvapotranspiration (ET) is a key process of the water cycle in general and in ecohydrology in particular. Measuring ET in forest eco-hydrosystems allows us to gain a better understanding of the response of forests to drought events, and to better anticipate the effects of climate change. Punctual (e.g. lysimeters or sapflow measurements) or integrative measurement methods (e.g. eddy covariance tower) can be used to estimate ET at the forest stand scale but these methods are not without limitations (e.g., resolution issues, representativeness, not adapted to mountainous areas).Superconducting gravimeters can be used to study ET. These gravimeters can be deployed in both flat and mountainous environments. In this work, we studied the hydrological residuals (i.e., hydrologically induced gravity variations) of 5 superconducting gravimeters located in different contexts. We interpreted the daily decreases in the stacked hydrological residual as the loss of water mass due to evapotranspiration. These results were compared with those of the SimpKcET water balance model.The results underline that the detectability of the ET signal depends strongly on the configuration of the gravimetric station, the topography and the type of ecosystem. We show that gravimeters located on summit area and in a forested context can detect the seasonality of ET. Conversely, gravimeters located in flat or underground areas and with a significant masking effect are unable to detect ET.Gravimetry therefore has a strong complementarity with conventional methods used to study ET and could contribute to a better understanding of water fluxes in forested ecosystems
Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration
No full textInternational audienceWe report on the -ray emission above 100~MeV from the GOES M3.3 flare SOL2012-06-03. The hard X-ray (HXR) and microwave emissions have typical time profiles with a fast rise to a well-defined peak followed by a slower decay. The >100~MeV emission during the prompt phase displayed a double-peaked temporal structure with the first peak following the HXR and microwaves, and the second one, about three times stronger, occurring seconds later. The time profiles seem to indicate two separate acceleration mechanisms at work, where the second -ray peak reveals a potentially pure or at least largely dominant ion acceleration. The Atmospheric Imaging Assembly imaging shows a bright elliptical ribbon and a transient brightening in the north-western (NW) region. Nonlinear force-free extrapolations at the time of the impulsive peaks show closed field lines connecting the NW region to the south-eastern part of the ribbon and the magnetic topology revealed clusters of nulls. These observations suggest a spine-and-fan geometry, and based on these observations we interpret the second -ray peak as being due to the predominant acceleration of ions in a region with multiple null points. The >100 MeV emission from this flare also exhibits a delayed phase with an exponential decay of roughly 350 seconds. We find that the delayed emission is consistent with ions being trapped in a closed flux tube with gradual escape via their loss cone to the chromosphere