S319.2.04 — Galaxies at z~6: physical properties at the edge of the cosmic reionization

Date & Time

Aug 11th at 3:00 PM until 3:15 PM




Rating ( votes)

Author(s): Stephane De Barros1, Eros Vanzella1, Laura Pentericci2, Adriano Fontana2, Andrea Grazian2, Marco Castellano2

Institution(s): 1. INAF-OABO, 2. INAF-OAR

An important effort has been recently made to detect spectroscopically galaxies at z~6 and higher where the cosmic reionization is thought to occur. The drop of the fraction of Lyman Alpha Emitters at z>6 is currently interpreted as an effect of the increasing neutral hydrogen density.
We present the result of the latest VLT/FORS2 program (PI: Pentericci) and combine them with results from other programs to perform a large census of z~6 galaxies. We derive their physical properties as stellar mass and dust attenuation with an SED fitting tool including nebular emission which is of primeval importance because IRAC1 and IRAC2 channels are strongly contaminated by emission lines.
We take a special care to derive with precision the redshift of non Lyman Alpha Emitters to perform a comparison of their properties with the Lyman Alpha Emitter population and derive as accurately as possible the fraction of Lyman Alpha Emitters. In particular, we compare the UV beta slope with the Lya equivalent width which are known to correlate at lower redshift.
We also report the detection of few peculiar z~6 galaxies with possibly extremely blue UV beta slope (~ -3) and Lyman Alpha Emitters with SFR(Lya) > SFR(UV), which in both case can be signatures of unusual stellar populations (e.g., (e.g., very hot and massive stars).