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

Abstract

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio\ninterferometer array currently in development, with an initial 256-element\narray to be deployed at the South African Radio Astronomy Observatory (SARAO)\nSquare Kilometer Array (SKA) site in South Africa. Each of the 6m, $f/0.23$\ndishes will be instrumented with dual-polarisation feeds operating over a\nfrequency range of 400-800 MHz. Through intensity mapping of the 21 cm emission\nline of neutral hydrogen, HIRAX will provide a cosmological survey of the\ndistribution of large-scale structure over the redshift range of $0.775 < z <\n2.55$ over $\\sim$15,000 square degrees of the southern sky. The statistical\npower of such a survey is sufficient to produce $\\sim$7 percent constraints on\nthe dark energy equation of state parameter when combined with measurements\nfrom the Planck satellite. Additionally, HIRAX will provide a highly\ncompetitive platform for radio transient and HI absorber science while enabling\na multitude of cross-correlation studies. In this paper, we describe the\nscience goals of the experiment, overview of the design and status of the\nsub-components of the telescope system, and describe the expected performance\nof the initial 256-element array as well as the planned future expansion to the\nfinal, 1024-element array.\n