Fisher Matrix Predictions for Detecting the Cosmological 21-cm Signal with the Ooty Wide Field Array (OWFA)

Abstract

We have used the Fisher matrix formalism to quantify the prospects of detecting the z=3.35 redshifted 21-cm HI power spectrum with the upcoming radio-imterferometric array OWFA. OWFA’s frequency and baseline coverage spans comoving Fourier modes in the range 1.8×10−2≤k≤2.7 Mpc−1. The OWFA HI signal, however, is predominantly from the range k≤0.2 Mpc−1. The larger modes, though abundant, do not contribute much to the HI signal. In this work, we have focused on combining the entire signal to achieve a detection. We find that a 5−σ detection of A HI is possible with ∼150 h of observations, here A2HI is the amplitude of the HI power spectrum. We have also carried out a joint analysis for A HI and β the redshift space distortion parameter. Our study shows that OWFA is very sensitive to the amplitude of the HI power spectrum. However, the anisotropic distribution of the k modes does not make it very suitable for measuring β.