Journal of Astrophysics and Astronomy

, Volume 24, Issue 1–2, pp 23–35 | Cite as

HI fluctuations at large redshifts: II — the signal expected for the GMRT

  • Somnath Bharadwaj
  • Sanjay K. Pandey


For the GMRT, we calculate the expected signal from red-shifted HI emission at two frequency bands centered at 610 and 325 MHz. The study focuses on the visibility-visibility cross-correlations, proposed earlier as the optimal statistical estimator for detecting and analyzing this signal. These correlations directly probe the power spectrum of density fluctuations at the redshift where the radiation originated, and thereby provide a method for studying the large scale structures at large redshifts. We present detailed estimates of the correlations expected between the visibilities measured at different baselines and frequencies. Analytic fitting formulas representing the salient features of the expected signal are also provided. These will be useful in planning observations and deciding an optimal strategy for detecting this signal.

Key words

Cosmology: theory, observations, large scale structures diffuse radiation 


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Copyright information

© Indian Academy of Sciences 2003

Authors and Affiliations

  • Somnath Bharadwaj
    • 1
  • Sanjay K. Pandey
    • 2
  1. 1.Department of Physics and Meteorology & Center for Theoretical StudiesI.I.T. KharagpurIndia
  2. 2.Department of MathematicsL.B.S. CollegeGondaIndia

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