HSTbanner

AR 13903 (Archival Research)

Sat Jul 20 08:50:38 GMT 2024

Principal Investigator: Matthew McQuinn
PI Institution: University of Washington
Investigators (xml)

Title: quasar lifetimes and helium reionization from HeII proximity zones
Cycle: 22

Abstract
The Cosmic Origins Spectrograph {COS} has gathered science grade HeII Lyman-alpha forest spectra towards 22 quasars. The vast majority of these show an enhancement in the ionization of helium at the redshift of the background quasar {the line-of-sight proximity zone} and most also show additional enhancements along the line-of-sight owing to adjacent quasars {transverse proximity zones}. These zones can be used to constrain the lifetimes of a statistically representative set of quasars on the extremely interesting timescale of 1-100 Myr and, at the higher redshifts probed by HST/COS, also the reionization of the second electron of helium. However, to extract this information requires radiative transfer calculations. We outline a regimen of such calculations that should lay the groundwork to be able to interpret HST/COS HeII Lyman-alpha forest observations.