In this talk, I will present the Vera Rubin Observatory Legacy Survey of Space and Time (VRO LSST). During the next decade, VRO will obtain high-resolution optical images of the Southern Sky at unprecedented depths. LSST is designed to address four science areas: probing dark energy and dark matter, taking an inventory of the solar system, exploring the transient optical sky and mapping the...
After a brief summary of results of LIGO-Virgo O3 observational run, I will present the future plans for the LIGO-Virgo-KAGRA network. I will then discuss the status and plans for the third generation detectors, Einstein Telescope and Cosmic Explorer. Finally, I will review the scientific potential of the upcoming detectors and the connections with the PNHE community.
The Laser Interferometer Space Antenna (LISA) is the large mission of ESA for observing gravitational waves (GW) from space. It has a huge science case and will observe a large number of GW sources making an important contribution to the multi-messenger astronomy. LISA is finishing its phase A and will be launched mid-2030s. In this talk, we will briefly describe the mission, give its current...
The gravitational-wave observatories LIGO and Virgo have so far detected several tens of stellar-mass compact binary mergers, but many more sources, too faint to be detected, lurk below the noise, creating a stochastic background. On the other end of the mass scale, super-massive binary black hole mergers are expected to create a stochastic background observable with pulsar timing arrays. I...
L’effondrement du coeur de fer des étoiles massives donne naissance aux objets compacts et à une diversité d’explosions. Je décrirai des travaux théoriques et numériques développés pour comprendre les propriétés de l’objet compact et de l’explosion associée. Des instabilités hydrodynamiques telles que SASI ou la convection due aux neutrinos jouent un rôle important pour déclencher l’explosion...
The first detection of gravitational waves (GWs) from a binary neutron
star merger (GW170817) by the LIGO-Virgo collaboration together with
an electromagnetic counterpart has brilliantly given birth to
multi-messenger astronomy. In the coming years, the GW detector
network sensitivity will be further increased making this rapidly
evolving new astronomy challenge our understanding of hot...
Dans cet exposé, je présenterai les enjeux scientifiques de l’étude des sursauts gamma et des sources astrophysiques d’ondes gravitationnelles qui produisent également de la lumière. L’accent sera mis dans ce second cas sur les coalescences de système binaires d’objets compacts. J’essaierai de résumer quelles sont les principales questions qui se posent sur la compréhension physique de ces...
This talk will give a brief summary of the activities of the GdR RESANET at the interface between nuclear physics and astrophysics. It will present activities in measurements of nuclear cross sections for astrophysical processes and in the modelling of neutron stars and associated phenomena, such as for instance gravitational wave physics.
Ce séminaire présentera le GdR Ondes Gravitationnelles, son rôle, sa structure, ses groupes de travails et ses actions récentes
X-ray satellites like XRISM (to be launched in early 2023) and, in a more distant future, Athena (2030+), will revolutionize our spectral view of compact objects. Thanks to their onboard calorimeters, they will provide an energy resolution of a few eV in the broad band (~1-10 keV) X-ray range, a factor several tens of times better than present satellites, especially above 6 keV.
I will...
50 years after the pioneering experiments, X-ray spectroscopy and timing techniques can be considered as well established. Nonetheless, one prominent feature of X-ray light has not been explored as scrupulously as others: its polarization. Between 1980 and 2000, the instruments were not sensitive enough to go beyond the first X-ray polarimetric results acquired in the 70s but the development...
La radio-astronomie vit actuellement une révolution majeure avec la mise en place de SKA au niveau mondial et le développement de précurseurs et éclaireurs à travers le monde. Depuis 2021, la France est officiellement rentrée dans SKA. Les précurseurs (e.g. MeerKAT) tournent à plein régime, et à très basses fréquences, un nouvel observatoire très sensible (NenuFAR) se met en place à la Station...
The study of pulsars started at the Nançay Observatory in the mid-1980s, after the discovery of the first millisecond pulsar. Since then, several generations of instruments have been developed as well as a wide spectrum of projects ranging from the characterisation of emission processes or the production of precise ephemerides for high energy observatories to the use of pulsars as natural...
L'étude des rayons cosmiques d'ultra-haute énergie (UHECRs) s'inscrit dans un effort global d'élucidation des phénomènes cosmiques de très haute énergie. La dernière décennie d'observation des UHECRs a permis d'affiner considérablement les mesures et d'accroître le volume de données disponibles. Si ces progrès n'ont pas encore conduit à l'identification des sources, ni éclairé autant qu'il...
L'astronomie gamma de basse énergie explore de nombreux domaines de recherche en astrophysique (pulsars, trous noirs, noyaux actifs de galaxie, nucléosynthèse, ...). Elle garde un grand potentiel de découvertes, tout particulièrement en lien avec l'astronomie des phénomènes rapides et l'astronomie multi-messagers. Pendant cette présentation , je ferai un état des lieux rapide des thèmes les...
The bulk of the cosmic rays we see at Earth are at a few GeV. Most of them are expected to be accelerated in old supernova remnants (10 000 yrs and more). Indeed many old SNRs are readily observed in GeV gamma rays, and those interacting with interstellar clouds are particularly bright.
The GeV emission is essentially pio0-decay, but can be due to two acceleration mechanisms:
-...
With the advent of the European Gaia astrometry mission and the constantly improving geodetic VLBI program who now provide both optical and radio reference frames with precisions better than 0.1 mas, challenging questions arise about the location of the optical centroid with respect to the radio one in extragalactic radio sources. We propose a study aiming at identifying which mechanisms are...
Les simulations PIC ont révolutionné notre compréhension des phénomènes dissipatifs et d'accélération de particules dans les plasmas spatiaux et astrophysiques. Au cours de la dernière décennie, ces véritables observatoires et microscopes numériques ont rencontré de nombreux succès dans la communauté française, comme l'étude des chocs non-collisionnels, la reconnexion magnétique, ou encore...
Microturbulence produced by plasma instabilities plays an important role in the dynamics and dissipation mechanisms of relativistic astrophysical collisionless shocks, such as those associated with gamma-ray bursts and blazar environments. We present the tenets of an analytical model that describes the dynamics of the precursor of relativistic unmagnetized collisionless shock waves in...
Cosmic Rays with energies below a fraction of EeV are coming from our galaxy but the way they are produced and they propagate to the Earth is still widely unknown. I will address recent progresses made in our understanding of Cosmic Ray acceleration and propagation on the point of view of microphysics and phenomenological studies. Then, I will shortly discuss why Cosmic Rays feed back are...
Galactic cosmic-rays (GCRs) are thought to be accelerated in strong shocks induced by massive star winds and supernova explosions sweeping across the interstellar medium. But the phase of the interstellar medium from which the CRs are extracted has remained elusive up to now. We have studied in detail the GCR source composition deduced from recent measurements by the AMS-02, Voyager 1 and...
Unsuccessful searches for new physics in the TeV domain at the LHC so far cast some doubt about the predictivity level of some theoretical frameworks beyond the standard model of particle physics that lead to dark matter candidates. Hierarchies among scenarios have been reshuffled and are now more and more ruled according to the plausibility of dark matter production in the early universe....
Context. The Schwarzschild precession of the star S2 which orbits the massive black hole at the centre of the milky way could recently be detected with $\sim12\,\text{arc-minutes}$ per orbit by GRAVITY Collab. et al. (2020). The result also improved the $1\sigma$ upper bound on a possibly present dark continuous extended mass distribution (e.g. faint stars, stellar remnants, stellar mass...
The Fermi GeV excess has kept physicists busy for the past decade. First attributed to dark matter annihilation, the favored explanation to date is an unresolved population of millisecond pulsars (MSPs), hiding in the Galactic Bulge. In order to prove this hypothesis, a multi-wavelength study is now needed. In a recent work [arXiv:2012.03580], we demonstrated that if the GeV excess is caused...
The planet-size network of millimeter antennas Event Horizon Telescope (EHT) has recently deliv-ered images of the surroundings of the supermassive compact object M87* at the center of the galaxy Messier 87. Such images are crucial to better understand the physics at play in a strong gravitational field environment. They might also allow to probe the extreme relativistic effects on the...
Polarimetry has proven to be one of the most resourceful observational methods in astronomy, but it is probably in the field of quasars that polarimetry contributed the most. And what better waveband to observe quasars than in the ultraviolet? This is both where the quasar's central engine (a supermassive black hole and its accretion disk) emit the most, and where the polluting starlight...
