Open AccessLensing of 21‐cm absorption haloes of z ∼ 2–30 first galaxies
Author(s) -
Zhang Pengjie,
Zheng Zheng,
Cen Renyue
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.12090.x
Subject(s) - physics , galaxy , astrophysics , reionization , cosmology , sky , absorption (acoustics) , weak gravitational lensing , cosmic cancer database , redshift , astronomy , optics
ABSTRACT Extended 21‐cm absorption regions (dubbed ‘21‐cm absorption haloes’) around first galaxies at z ∼ 30 are likely the first distinctive structures accessible to radio observations. Though the radio array capable of detecting and resolving them must have ∼200 km 2 total collecting area, given the great impact of such detections to the understanding of the reionization process and cosmology, such radio survey would be extremely profitable. As an example, we point out a potentially useful byproduct of such survey. The resolved 21‐cm absorption ‘haloes’, likely close to spherical, can serve as (almost) ideal sources for measuring the cosmic shear and mapping the matter distribution to z ∼ 30 . We investigate the expected lensing signal and consider a variety of noise contributions on the shear measurement. We find that signal‐to‐noise ratio (S/N) ∼ 1 can be achieved for individual ‘haloes’. Given millions of 21‐cm absorption ‘haloes’ across the sky, the total S/N will be comparable to traditional shear measurement of ∼10 9 galaxies at z ∼ 1 .