# Fisher Matrix Based Predictions for Measuring the z = 3.35 Binned 21-cm Power Spectrum using the Ooty Wide Field Array (OWFA)

## TL;DR

This paper predicts the ability of the OWFA telescope to measure the 21-cm power spectrum at redshift 3.35 using Fisher matrix analysis, highlighting detection prospects and optimal observation times.

## Contribution

It provides the first detailed Fisher matrix-based forecast for 21-cm power spectrum detection with OWFA at z=3.35, including optimal observation strategies.

## Key findings

- 5 sigma detection possible with 1,000 hours in certain k-bins
- Peak SNR of 10 sigma in 0.1-0.2 Mpc^{-1} range with 2,000 hours
- Limited gains beyond 1,000 hours of observation in a single field

## Abstract

We use the Fisher matrix formalism to predict the prospects of measuring the redshifted 21-cm power spectrum in different $k$-bins using observations with the upcoming Ooty Wide Field Array (OWFA) which will operate at $326.5 {\rm MHZ}$. This corresponds to neutral hydrogen (HI) at $z=3.35$, and a measurement of the 21-cm power spectrum provides an unique method to probe the large-scale structures at this redshift. Our analysis indicates that a $5 \sigma$ detection of the binned power spectrum is possible in the $k$ range $0.05 \leq k \leq 0.3 \, {\rm Mpc}^{-1}$ with $1,000$ hours of observation. We find that the Signal-to-Noise ratio (${\rm SNR}$) peaks in the $k$ range $0.1- 0.2\, {\rm Mpc}^{-1}$ where a $10 \sigma$ detection is possible with $2,000$ hours of observations. Our analysis also indicates that it is not very advantageous to observe much beyond $1,000$ hours in a single field of view as the ${\rm SNR}$ increases rather slowly beyond this in many of the small $k$-bins. The entire analysis reported here assumes that the foregrounds have been completely removed.