Bharadwaj, Somnath ; Nath, Biman B. ; Sethi, Shiv K. (2001) Using HI to probe large scale structures at z∼3 Journal of Astrophysics and Astronomy, 22 (1). pp. 21-34. ISSN 0250-6335
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Official URL: http://doi.org/10.1007/BF02933588
Related URL: http://dx.doi.org/10.1007/BF02933588
Abstract
The redshifted 1420 MHz emission from the HI in unresolved damped Lyman-α clouds at high z will appear as a background radiation in low frequency radio observations. This holds the possibility of a new tool for studying the universe at high-z, using the mean brightness temperature to probe the HI content and its fluctuations to probe power spectrum. Existing estimates of the HI density atz−3 imply a mean brightness temperature of 1 mK at 320 MHz. The cross-correlation between the temperature fluctuation across different frequencies and sight lines is predicted to vary from 10−7 K2 to 10−8 K2 over intervals corresponding to spatial scales from 10 Mpc to 40 Mpc for some of the currently favoured cosmological models. Comparing this with the expected sensitivity of the GMRT, we find that this can be detected with ∼ 10 hrs of integration, provided we can distinguish it from the galactic and extragalactic foregrounds which will swamp this signal. We discuss a strategy based on the very distinct spectral properties of the foregrounds as against the HI emission, possibly allowing the removal of the foregrounds from the observed maps.
Item Type: | Article |
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Source: | Copyright of this article belongs to Indian Academy of Sciences, Bengaluru. |
Keywords: | Cosmology: Theory; Observations; Large Scale Structures Diffuse Radiation. |
ID Code: | 116373 |
Deposited On: | 09 Apr 2021 04:56 |
Last Modified: | 09 Apr 2021 04:56 |
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