Intergalactic Interactions: A Higgs Centre Workshop on the Intergalactic Medium

Toward the beginning of the reionization of intergalactic helium

25 Jun 2013, 10:10

30m

Lecture Theatre (Royal Observatory, Edinburgh)

Contributed Talk Helium in the IGM

Speaker

Dr Wei Zheng (Johns Hopkins University)

Description

From the HST/COS spectra of selected quasars at z~>3.5, we find significant flux blueward of the HeII Lyα wavelength. The absorption profile suggests large "bubbles" of ionized helium embedded in the intergalactic medium. We find that the intensity of He+ ionizing field weakens considerably at z~3, and the reionization of the intergalactic helium started around z=3.5.