The Wide-field High-resolution Infrared TElescope (WHITE)

The Wide-field High-resolution Infrared TElescope (WHITE) will be dedicated in the first years of its life to carrying out a few (well focused in terms of science objectives and time) legacy surveys. WHITE would have an angular resolution of ~0.3'' homogeneous over ~0.7 sq. deg. in the wavelength range 1 - 5 um, which means that we will very efficiently use all the available observational time during night time and day time. Moreover, the deepest observations will be performed by summing up shorter individual frames. We will have a temporal information that can be used to study variable objects. The three key science objectives of WHITE are : 1) A complete survey of the Magellanic Clouds to make a complete census of young stellar objects in the clouds and in the bridge and to study their star formation history and the link with the Milky Way. The interaction of the two clouds with our Galaxy might the closest example of a minor merging event that could be the main driver of galaxy evolution in the last 5 Gyrs. 2) The building of the first sample of dusty supernovae at z<1.2 in the near infrared range (1-5 um) to constrain the equation of state from these obscured objects, study the formation of dust in galaxies and build the first high resolution sample of high redshift galaxies observed in their optical frame 3) A very wide weak lensing survey over that would allow to estimate the equation of state in a way that would favourably compete with space projects.Comment: Invited talk to the 2nd ARENA Conference : "The Astrophysical Science Cases at Dome C" Potsdam 17-21 September, 200

Pupil stabilization for SPHERE's extreme AO and high performance coronagraph system

We propose a new concept of pupil motion sensor for astronomical adaptive optics systems and present experimental results obtained during the first laboratory validation of this concept. Pupil motion is an important issue in the case of extreme adaptive optics, high contrast systems, such as the proposed Planet Finder instruments for the ESO and Gemini 8-meter telescopes. Such high contrast imaging instruments will definitively require pupil stabilization to minimize the effect of quasi-static aberrations. The concept for pupil stabilization we propose uses the flux information from the AO system wave-front sensor to drive in closed loop a pupil tip-tilt mirror located in a focal plane. A laboratory experiment validates this concept and demonstrates its interest for high contrast imaging instrument.Comment: This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at http://www.opticsexpress.org/abstract.cfm?id=144687 on the OSA websit

INTEGRAL discovery of non-thermal hard X-ray emission from the Ophiuchus cluster

We present the results of deep observations of the Ophiuchus cluster of galaxies with INTEGRAL in the 3-80 keV band. We analyse 3 Ms of INTEGRAL data on the Ophiuchus cluster with the IBIS/ISGRI hard X-ray imager and the JEM-X X-ray monitor. In the X-ray band using JEM-X, we show that the source is extended, and that the morphology is compatible with the results found by previous missions. Above 20 keV, we show that the size of the source is slightly larger than the PSF of the instrument, and is consistent with the soft X-ray morphology found with JEM-X and ASCA. Thanks to the constraints on the temperature provided by JEM-X, we show that the spectrum of the cluster is not well fitted by a single-temperature thermal Bremsstrahlung model, and that another spectral component is needed to explain the high energy data. We detect the high energy tail with a higher detection significance (6.4 sigma) than the BeppoSAX claim (2 sigma). Because of the imaging capabilities of JEM-X and ISGRI, we are able to exclude the possibility that the excess emission comes from very hot regions or absorbed AGN, which proves that the excess emission is indeed of non-thermal origin. Using the available radio data together with the non-thermal hard X-ray flux, we estimate a magnetic field B ~ 0.1-0.2 mu G.Comment: 8 pages, 9 figures, accepted by A&