Résumé / Abstract Seminaire_IAP
« The Lyman Continuum Escape Fraction and Other Curiosities in HST Deep Surveys »

Harry Teplitz
Infrared Processing Analysis Center (IPAC), California Inst. Technology (Caltech) (Pasadena, California, Etats-Unis d'Amérique)

Massive starbursts may have played a dominant role in the reionization of the Universe. Their contribution depends in part upon the fraction of ionizing radiation that escapes from the intrinsic opacity of galaxies below the Lyman limit. Direct measurement of the escape fraction, fesc, is impossible at the epoch of reionization, because intervening absorbers make the IGM opaque to Lyman continuum photons. Instead, fesc must be measured at lower redshifts in objects that are analogous to the galaxies responsible for reionization.
I present the results of a comprehensive HST survey to measure or limit the value of fesc in starbursts near z=1 and z=3. We have used the Hubble Space Telescope to perform the deepest search to date for escaping Lyman continuum radiation. At redshifts near unity, the Lyman continuum is not detected. A subset of galaxies at z=3.1 have been found emitting ionizing radiation, but it is unclear why these galaxies have such large escape fractions. To better understand the mechanisms which allow for large escape fractions, we have obtained a single, 32-orbit image with the WFC3/UVIS camera on HST to obtain resolved images of escaping Lyman continuum (LyC) radiation from Lyman Break Galaxies and Lyman-alpha Emitters. In the coming year, we will obtain deep UV images of the GOODS-North field and the Hubble Ultra Deep Field to extend the study of the LyC to z=2.
vendredi 4 novembre 2011 - 11:00
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris
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