May 30, 2012

Sowgat Muzahid, Inter-University Center for Astronomy and Astrophysics, India

"A High-resolution Study of Intergalactic O VI Absorbers at High-redshift "

The study of the tenuous intergalactic medium (IGM) is extremely important because it forms the primary reservoir of baryons throughout the cosmic ages. The absorption lines seen in the spectra of distant QSOs allow us to study the IGM. The resonant lines of O VI, in particular, are good candidates to probe the low density IGM. The O VI absorbers are also supposed to trace the high temperature (T > 10^5 K) shock heated regions where most of the "missing baryons" could reside.
We have conducted a systematic survey of O VI absorbers at redshift ~2.3 in 18 high-resolution (R ~ 45,000) QSO spectra observed with the VLT/UVES and built the largest sample till date. In this talk the speaker will summarise the statistical nature of O VI absorbers and make a detailed comparison between properties of  high-z and low-z O VI absorbers.