Final results from EROS Microlensing search for Massive Compact Halo Objects

International audienceWe present the results of the EROS2 search for the hidden galactic matter of the halo through the gravitational microlensing of stars in the Magellanic clouds. Microlensing was also searched for and found in the Milky-Way plane, where foreground faint stars are expected to lens background stars. A total of 67 million of stars were monitored over a period of about 7 years. Hundreds of microlensing candidates have been found in the galactic plane, but only one was found towards the subsample of bright --well measured-- Magellanic stars. This result implies that massive compact halo objects (machos) in the mass range $10^{-7}M_\odo

Cosmology with Wide Field Astronomy

PoS(ICHEP 2010)441International audienceWide field astronomy has recently produced important results for the dark matter and dark energy problematics. I will summarize the scientific impact of the ongoing wide field surveys and focus on the future LSST program (Large Synoptic Survey Telescope). This program will use a 8.4 m diameter telescope, equipped with a 3.2 Gpixel wide field camera. Cosmological studies is one of his main objectives

Search for hidden turbulent gas through interstellar scintillation

Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected when the light of remote stars crosses a Galactic - disk or halo - refractive medium such as a molecular cloud. We present the promising results of a test performed with the ESO-NTT and the perspectives of detection.Comment: Structure and dynamics of disk galaxies, Petit Jean Mountain : United States (2013). arXiv admin note: substantial text overlap with arXiv:1208.637

Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds

In this article, we have investigated the possibility to distinguish between different galactic models through the microlensing parallax studies. We show that a systematic search for parallax effects can be done using the currently running alert systems and complementary photometric telescopes, to distinguish between different lens distance distributions. We have considered two galactic dark compact objects distributions, with total optical depths corresponding to the EROS current upper limits. These models correspond to two extreme hypothesis on a three component galactic structure made of a thin disc, a thick disc, and a spherically symmetric halo. Our study shows that for sub-solar mass lenses, an exposure of $8\times 10^7$ star$\times$yr toward LMC should allow to distinguish between these two extreme models. In addition the self-lensing hypothesis (lensing by LMC objects) can efficiently be tested through the method proposed here.Comment: 10 pages, 12 eps figures. To be published in A&A (accepted version). Minor changes: - Discussion added on the differential velocity of the thick galactic disk with respect to the thin disk. - Quality and lisibility of figures improved. - Typo errors correcte

Possible use of the dedicated MARLY one meter telescope for intensive supernovae studies

The EROS2 microlensing search will end at the end of 2002. Apart of this microlensing search, EROS has discovered ~70 supernovae during 8 periods partially dedicated to a SN search. In this document, we investigated a new way of using the EROS telescope (The MARLY) after this date, as a dedicated nearby supernovae photometer. The performance of a set-up with two cameras allowing to simultaneously perform BVRI and U photometry have been estimated. Each year, of order of 100 type Ia supernovae at z ~0.05 should be photometrically followed-up during 80 days with a precision of 2% in BVRI and ~3,5% in U.Comment: You can find the full resolution of this report at http://www.lal.in2p3.fr/presentation/bibliotheque/publications/ publicationsLAL01.html/LAL0171.p

Search for Turbulent Gas through Interstellar Scintillation

Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected when the light of remote stars crosses a Galactic - disk or halo - refractive medium such as a molecular cloud.We present the promising results of a test performed with the ESO-NTT and the perspectives.Comment: Tenth Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe, Los-Angeles : \'Etats-Unis (2012

Baryonic acoustic oscillations simulations for the Large Synoptic Survey Telescope (LSST)

The baryonic acoustic oscillations are features in the spatial distribution of the galaxies which, if observed at different epochs, probe the nature of the dark energy. In order to be able to measure the parameters of the dark energy equation of state to high precision, a huge sample of galaxies has to be used. The Large Synoptic Survey Telescope will survey the optical sky with 6 filters from 300nm and 1100nm, such that a catalog of galaxies with photometric redshifts will be available for dark energy studies. In this article, we will give a rough estimate of the impact of the photometric redshift uncertainties on the computation of the dark energy parameter through the reconstruction of the BAO scale from a simulated photometric catalog.Comment: 4 pages, 2 figures, 10th Rencontres de Blois proceedin

Searching for Galactic Hidden Gas through interstellar scintillation

International audienceConsidering the results of baryonic compact massive ob jects searches through microlensing [1], cool molecular hydrogen (H_2 - He) clouds should now be seriously considered as a possible major component of the Galactic hidden matter. It has been suggested that a hierarchical structure of cold H_2 could fill the Galactic thick disk [8] or halo [3], providing a solution for the Galactic hidden matter problem. This gas should form transparent "clumpuscules" of ~ 10 AU size, with a column density of 10^ 24-25 cm^-2 , and a surface filling factor smaller than 1%. The OSER project (Optical Scintillation by Extraterrestrial Refractors) is proposed to search for scintillation of extra-galactic sources through these Galactic - disk or halo - transparent H_2 clouds. This project should allow one to detect (stochastic) transverse gradients of column density in cool Galactic molecular clouds of order of ~ 3 × 10^-5 g/cm^2 /10 000 km. We present the expectations from a complete simulation of the interstellar scintillation process. Test observations have been obtained through known nebulae to probe the concept in a controlled situation; we show preliminary results from their analysis