Galaxies at the Frontiers of the Universe

by Nicolas Laporte

at Astrophysics and Cosmology Seminar

Wed, 21 Nov 2018, 11:10
Physics building (#54) room 207

Abstract

The most intriguing question of modern extra galactic astronomy is to locate and study the first galaxies in order to determine when they emerged from the dark ages what are their physical properties and what role do they play in governing the transition of intergalactic hydrogen from a neutral state to one that is ionised Measures of the optical depth of electron scattering by the Planck satellite indicates this cosmic reionisation was a fast process occurring relative late over the redshift interval 12 lt z lt 6 Moreover recently high redshift galaxies discovered at fascinating distances z 8 11 and more were interpreted in terms of ages and intense star formation histories These galaxies are revealed mature by spectral synthesis identifying the Balmer discontinuity the dust attenuated far UV distribution as well as very faint emission lines with ages of 500 million years starting just after the Big Bang indicating a formation redshift of 15 or more earlier than expected by the current paradigm Such early systems with significant stellar masses and star formation rates which decline with time are not easily reproduced by contemporary numerical simulations After discussing the scientific context of this topic I will describe the method used to identify distant galaxies to measure the age of their stellar population and to determine their physical properties

Created on 16-11-2018 by Bar Lev, Yevgeny (ybarlev)
Updaded on 16-11-2018 by Bar Lev, Yevgeny (ybarlev)