The Hydrogen Intensity and Real-time Analysis eXperiment: 256-Element Array Status and Overview

TL;DR

HIRAX is a radio interferometer array designed for cosmological intensity mapping of neutral hydrogen, aiming to study large-scale structure, dark energy, and transient phenomena with a 256-element setup and future expansion plans.

Contribution

This paper presents the design, status, and expected performance of the HIRAX 256-element array, a novel instrument for cosmological and transient radio science.

Findings

Initial array performance estimates indicate strong potential for large-scale structure mapping.

The experiment can constrain dark energy parameters with about 7% precision.

Future expansion to 1024 elements will enhance scientific capabilities.

Abstract

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio interferometer array currently in development, with an initial 256-element array to be deployed at the South African Radio Astronomy Observatory (SARAO) Square Kilometer Array (SKA) site in South Africa. Each of the 6m, $f/0.23$ dishes will be instrumented with dual-polarisation feeds operating over a frequency range of 400-800 MHz. Through intensity mapping of the 21 cm emission line of neutral hydrogen, HIRAX will provide a cosmological survey of the distribution of large-scale structure over the redshift range of $0.775 < z < 2.55$ over $\sim$15,000 square degrees of the southern sky. The statistical power of such a survey is sufficient to produce $\sim$7 percent constraints on the dark energy equation of state parameter when combined with measurements from the Planck satellite. Additionally, HIRAX will provide a highly competitive platform for radio transient and HI absorber science while enabling a multitude of cross-correlation studies. In this paper, we describe the science goals of the experiment, overview of the design and status of the sub-components of the telescope system, and describe the expected performance of the initial 256-element array as well as the planned future expansion to the final, 1024-element array.