DUCOURANT , C.

Accurate knowledge of the morphology of halos and its evolution are key constraints on the galaxy formation model as well as a determinant parameter of the strong-lensing phenomenon. Using the cosmological hydrodynamic simulation, the Evolution and Assembly of GaLaxies and their Environments (EAGLE), we aim to provide a comprehensive analysis...

The Bordeaux observatory astrometric group has performed significant efforts to produce and exploit large data base surveys. This effort has been realized to extend and densify the ICRS materialized by Tycho2 catalogue. This effort concerns the systematic re-observation of the Bordeaux Carte du Ciel zone with the Bordeaux automatic CCD meridian...

We present a proper motion catalogue of 2670974 stars, covering the declination zone +11°<=?<=+18°. Proper motions were derived from the comparison of the positional M2000 catalogue (systematic observations of the Bordeaux Carte du Ciel Zone with the meridian circle, completed in 2000) with positions derived from the reduction of 512 Carte du...

Context: .This work is part of a program of proper motion measurements in the Bordeaux Carte du Ciel zone.Aims.We present the CdC2000 catalogue issued from the reduction of the complete Bordeaux Carte du Ciel zone observed at the begining of last century with the Bordeaux astrograph.Methods.Plates have been individually reduced using the...

Tables 4 provides the compiled list of 478 known gravitationally lensed systems (GL), including candidates (each line corresponds to an image of the lense) together with informations from the Gaia DR2 whenever a source was found at less than 0.5 arcsec from the literature's position of the image. (1) Name, (2) ref - bibliographic reference (*...

Gaia was mainly designed for the study of stars in our Galaxy. However, by continuously scanning the entire sky, it also provides informations on all kind of objects that fall in its fields of view, including extragalactic objects. Amongst these extragalactic sources, quasars stand out to be some of the most peculiar objects that Gaia observe....

We report the spectroscopic confirmation and modeling of the quadruply imaged quasar GRAL 113100–441959, the first gravitational lens (GL) to be discovered from a machine learning technique that only relies on the relative positions and fluxes of the observed images without considering colour informations. Follow-up spectra obtained with...

Context. Thanks to its spatial resolution, the ESA/Gaia space mission offers a unique opportunity to discover new multiply imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions.Aims. In this paper, we address the detection of the known multiply imaged quasars from the Gaia Data Release 2 (DR2)...

Context. Multiply imaged gravitationally lensed quasars are among the most interesting and useful observable extragalactic phenomena. Because their study constitutes a unique tool in various fields of astronomy, they are highly sought, but difficult to find. Even in this era of all-sky surveys, discovering them remains a great challenge, with...

The Gaia GraL catalogue of clusters consist of 2,058,962 clusters with three components and 70,697 clusters with four components. Each of these clusters satisfied the following conditions: i) Clusters are composed of three or four images in order to provide a sufficient number of constraints for identifying gravitational lens candidates. ii)...

Aims: In this work, we aim to provide a reliable list of gravitational lens candidates based on a search performed over the entire Gaia Data Release 2 (Gaia DR2). We also aim to show that the astrometric and photometric information coming from the Gaia satellite yield sufficient insights for supervised learning methods to automatically identify...

The discovery of multiply-imaged gravitationally lensed QSOs is fundamental to many astronomical and cosmological studies. However, these objects are rare and challenging to discover due to requirements of high-angular resolution astrometric, multiwavelength photometric and spectroscopic data. This has limited the number of known systems to a...

Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses group (GraL) uses machine learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars from the Gaia Data Release 2. This paper reports on the 12...