Candidats (proto-)amas de galaxies à grand redshift vus par le CFHT

Abstract : The properties of local galaxies (color, morphology, gas fraction, etc.) greatly depend on their environment. The differentiation occurred during their assembly. Current observations indicate that the peak of star formation occurred around z=2 and that dense environments used to be cradles of intense star formation, unlike today. This differentiation may be explained by observing the high-z progenitors of today’s most massive systems. However, such sources are rare. Good candidates are sub-millimeter galaxies, because they directly trace star formation. A sample of 82 such candidates named SPHerIC (Spitzer–Planck–Herschel infrared clusters) was made from the data of these three satellites. From them, 13 have been observer by the CFHT. I extracted as much information as I could from those new data in order to make SPHerIC more robust. After making JKs source catalogs with a self-made photometric pipeline, I made galaxy surface density maps in J–Ks color slices. I defined 8 colors using Berta et al. (2013) galaxy templates to constrain the redshift of galaxies. I show the coincidence between the position of JKs and IRAC-red overdensities with the position of SPIRE red sources. JKs color–magnitude diagrams (J–Ks vs Ks) along with models from Kodama et al. (1998) may exhibit a z~2 red sequence in 12 out of 13 fields. NIR color–color diagrams ([3.6]–[4.5] vs J–Ks) of IRAC-red sources are compatible with starforming models from Berta et al. (2013), also compatible with Planck and Herschel results. The analyses of our photometric data all converge toward the fact that our candidates are genuine high-z star-forming structures. From spectroscopic observations at the IRAM/30m telescope, I confirm for instance 2 structures at z>2. Infrared luminosities and SFRs derived from CO fluxes are consistent with high-SFR sources. In parallel, I have been involved in the Euclid Consortium. I studied the PSF variations of the VIS imager w.r.t. the spectral type of observed objects and their position on the focal plane. I show there is a limited impact on the PSF as long as the stars and galaxies are standard.
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Benjamin Clarenc. Candidats (proto-)amas de galaxies à grand redshift vus par le CFHT. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris-Saclay, 2018. Français. ⟨NNT : 2018SACLS234⟩. ⟨tel-01935501⟩

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