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Étude statistique des structures à grand redshift observées par les satellites Planck et Herschel

Abstract : Actual models and observations of the Universe agreed at large scale. But the formation of baryonic structures remains unknown. To constrain structure formation in the Universe, observatoins are needed at different redshift to see different evolution steps. Planck satellite gives an acces to objetcs in the redshift range z=2 to z=4. Thus we detect about 1200 extragalactic objects in 26% of the sky near galactic poles, candidates to be at high redshift. A sample of 228 sources is observed at higher sensibility and resolution than Planck with Herschel satellite. This lead to resolve ponctual Planck sources in several Herschel sources. So I identify three possible types of object : candidates sources of gravitationally amplified lenses, galaxy cluster candidates and alignement of sources along the line of sight. I find in the sample 11 sources amplified by gravitationnal lensing, some of the brightest of the submillimeter sky. Those have redshift between z=2.2 and z=3.6 (Canameras et al., 2015) and provide a zoom in the stellar formation of the far Universe. It let 217 overdensity of sources that I study. With their colour in Herschel data, I find an estimate of their density. 50% of Herschel fields have an overdensity greater than 10sigma using red sources colour selection (S250/S350 < 1.4 et S500/S350 > 0.6). This show that our ample is mainly composed of red overdensity. Fitting Herschel-SPIRE photometry with a modify black body at 35K, I show that the photmetric redshift distribution of Herschel sources peaks around z=2. Our sample is now composed of 11 lensed sources and 217 galaxy cluster candidates at z~2. These galaxy cluster candidates contain an average of 9 SPIRE sources in 4.5’ diameter beam. Individual sources have a luminosity distribution peaking at 4.1012 Lsun which leads to a star formation rate (SFR) of 700 Msun.yr-1 (Bell et al. 2003). This gives an estimate structure luminosity of 4.1013 Msun and an SFR of 7000 Msun.yr-1 assuming that sources are members of the same structure. Our sample traces dense structure at high star formation rate in the full sky. This sample will be a key in the comprehension of structure formation and star formation at redshift about z=2.
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Submitted on : Wednesday, January 27, 2016 - 9:24:10 AM
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David Guery. Étude statistique des structures à grand redshift observées par les satellites Planck et Herschel. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris Sud - Paris XI, 2015. Français. ⟨NNT : 2015PA112162⟩. ⟨tel-01262699⟩



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