The PEGASE project: characterisation of "Pegasi planets" and Brown Dwarfs

I will present the PEGASE project proposed within the framework of the CNES call for idea on flights in formation. This ambitious project, gathering a dozen laboratories, proposes an interferometry mission in infrared I(1.5 to 6 µm) with spectroscopic capabilities. The bases of the interferometer will reach up to 500m, giving to PEGASE a resolution higher than the milli-arcsecond. The interferometric recombination includes a very simple mode, measurement of the visibility by excursion of the optical path difference and a mode in black fringe or nulling. The very high angular resolution of the instrument and high dynamical range with the nulling mode will allow to consider exciting scientific objectives: the characterization of Pegasids or hot Jupiters, the study of the internal structure and the atmospheres of brown dwarfs and the analysis of the internal areas of proto-planetary disks. I will first of all describe the basic configuration of the mission and will show that its simplicity ensures the feasibility of the project. I will explain then the relevance of such an instrument for the characterization of Pegasids. I will detail finally the various possible technical options to be attached to the initial version, in order to increase the effectiveness of the mission and to extend its scientific objectives

The PEGASE project: characterisation of "Pegasi planets" and Brown Dwarfs

International audienc

The PEGASE project: characterisation of "Pegasi planets" and Brown Dwarfs

International audienc

The PEGASE project: characterisation of "Pegasi planets" and Brown Dwarfs

International audienc

Search for Lensing Signatures in the Gravitational-Wave Observations from the First Half of LIGO–Virgo’s Third Observing Run

International audienceWe search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo during O3a, the first half of their third observing run. We study: (1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; (2) how the interpretation of individual high-mass events would change if they were found to be lensed; (3) the possibility of multiple images due to strong lensing by galaxies or galaxy clusters; and (4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses

State of the art of the Virgo experiment

This study concerns information seeking and use models for professionals and their evolutions essentially, i.e. Information Access Practices. Coming from Anglo-Saxon literature, this new research trend evolves with the development of information science paradigms. So different information seeking and use models emerge in order to explain how professionals seek information and what can be done in order to help them. Two main categories can be distinguished: information seeking and use models versus the information retrieval models. So we will present today these models' diversity and we will evaluate them in order to see if a convergence is possible with the same vocabulary and procedures

State of the art of the Virgo experiment

This study concerns information seeking and use models for professionals and their evolutions essentially, i.e. Information Access Practices. Coming from Anglo-Saxon literature, this new research trend evolves with the development of information science paradigms. So different information seeking and use models emerge in order to explain how professionals seek information and what can be done in order to help them. Two main categories can be distinguished: information seeking and use models versus the information retrieval models. So we will present today these models' diversity and we will evaluate them in order to see if a convergence is possible with the same vocabulary and procedures