Galaxies Inside Stromgren Spheres of Luminous Quasars at z>6: Detection of The First Galaxies

Abstract

The intrinsic Lyman-alpha emission lines of normal galaxies before reionization are much absorbed by the damping wing of the Gunn-Peterson trough, rendering their direct detection nearly impossible, if their intrinsic line widths are less than ~100km/s. High redshift luminous quasars prior to the completion of cosmological reionization at z~6, on the other hand, are capable of producing large HII regions around them (Stromgren spheres) to allow their intrinsic Lyman-alpha emission lines to be transmitted without overwhelming absorption (Cen & Haiman 2000). We suggest that targeted observations at the Stromgren spheres of known luminous quasars at z >= 6 would be able to detect Lyman-alpha emission lines of galaxies inside the Stromgren spheres largely unattenuated. A tunable, very narrowband filter of Δλ\over λ~ 0.1% or a narrowband filter of Δλ\over λ~1% with follow-up spectroscopic identifications will be required. Such observations could directly observe the sources of cosmological reionization including possibly the Pop III galaxies at z=6-20 by JWST. Possible applications include determinations of the ionization state of the intergalactic medium, the sizes of the Stromgren spheres, the ages of the quasars, the luminosity function of high redshift galaxies and its evolution, the spatial distribution of galaxies and its evolution, the biased distribution of galaxies around quasars and the anisotropy of quasar emission. Observations using Keck-class telescopes may already be made to enable a differentiation between a fully neutral and a 10% neutral intergalactic medium at z>6.

Submitted to ApJ Letters, 10 pages

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Cited by in corpus (10)

• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• The First Cosmic Structures and their Effects
• Ionizing Photon Escape Fractions from High Redshift Dwarf Galaxies
• Probing reionization with Lyman-alpha emission lines
• Redshifted 21 cm Emission From the Pre-Reionization Era I. Mean Signal and Linear Fluctuations
• Constraining the Topology of Reionization Through Lyman-alpha Absorption
• Prospects for Redshifted 21-cm observations of quasar HII regions
• The Strömgren sphere, the environment and the reionization in the local universe of the highest redshift QSOs
• The apparent shape of the "Strömgren sphere'' around the highest-redshift QSOs with Gunn-Peterson troughs
• Cross-correlation studies as a probe of reionization physics