Quasars Probing Quasars: Shedding Light on the Environments, Emission Geometry, and Lifetimes of Quasars
Abstract
We have obtained high S/N moderate and high resolution Gemini and Keck spectra of the Ly(alpha) forests of a large sample of projected pairs of quasars with z> 2 and sub-arcminute separations. In these extremely rare sightlines, Ly(alpha) absorption, as measured in the background quasar spectrum, can be used to study the environment, emission geometry, and emission history of the foreground quasar, provided that the systemic redshift of the foreground quasar is known accurately. We propose to obtain low dispersion (R 1100) H-band spectra of 24 sub-arcminute z > 2 projected pairs of quasars, with NIRI and GNIRS to determine systemic redshifts from the narrow [OIII] (lambda) 5008 emission line accurate to 30km s^- 1. This will eliminate the current 4 hmpc uncertainty in the foreground quasars' radial position, resolving transverse length scales as small as 20 hkpc. We will then be able to precisely characterize the transverse proximity effect, measure the cross- correlation function of quasars with optically thick neutral gas, constrain the geometry of quasar emission and the quasar emission history on timescales from 8 × 10^4 to 3 × 10^6 years, and gain insights into the fluorescent recombination radiation emitted by Lyman limit systems illuminated by ultraviolet photons.
- Publication:
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NOAO Proposal
- Pub Date:
- February 2007
- Bibcode:
- 2007noao.prop..567H