CAAUL Seminar - The nature and evolution of luminous Hα emitters at z~0.8-2.2 from HiZELS - 30 janeiro 2014

Saul Kohn

University of Edinburgh, ROE, UK

Abstract / Resumo

The decline in number density of luminous Hα emitters has been responsible for the strongest changes the Hα luminosity function across the past ~11Gyr, which is mostly characterised by an evolution in the typical luminosity of star-forming galaxies (L*). Despite that, little is known about the nature and evolution of luminous emitters. In this work we present NIR spectra (obtained with the NTT, TNG and WHT) of ~100 luminous Hα emitters (>1.5 L*) at z~ 0.8, 1.5 and 2.2 from HiZELS. We unveil the nature of the Hα emitters by identifying AGN among the sample, either by their broad Hα lines, or by measuring [OIII]/Hβ and [NII]/Hα line ratios. We find that among these luminous Hα emitters, ~50% are AGN at all redshifts probed, showing little to no evolution in the AGN fraction. Using our own AGN-decontaminated sample of star forming galaxies, we derive the star-formation history for luminous Hα emitters since z~2.23, revealing a factor of 1000× evolution.   

30 de janeiro de 2014 | 11:00

Local

Faculdade de Ciências da Universidade de Lisboa

Edifício C8 | Sala 1.67