HIRAX: a probe of dark energy and radio transients

Abstract

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a new 400-800 MHz radio interferometer under development for deployment in South Africa. HIRAX will comprise 1024 six meter parabolic dishes on a compact grid and will map most of the southern sky over the course of four years. HIRAX has two primary science goals: to constrain Dark Energy and measure structure at high redshift, and to study radio transients and pulsars. HIRAX will observe unresolved sources of neutral hydrogen via their redshifted 21-cm emission line ('hydrogen intensity mapping'). The resulting maps of large-scale structure at redshifts 0.8-2.5 will be used to measure Baryon Acoustic Oscillations (BAO). BAO are a preferential length scale in the matter distribution that can be used to characterize the expansion history of the Universe and thus understand the properties of Dark Energy. HIRAX will improve upon current BAO measurements from galaxy surveys by observing a larger cosmological volume (larger in both survey area and redshift range) and by measuring BAO at higher redshift when the expansion of the universe transitioned to Dark Energy domination. HIRAX will complement CHIME, a hydrogen intensity mapping experiment in the Northern Hemisphere, by completing the sky coverage in the same redshift range. HIRAX's location in the Southern Hemisphere also allows a variety of cross-correlation measurements with large-scale structure surveys at many wavelengths. Daily maps of a few thousand square degrees of the Southern Hemisphere, encompassing much of the Milky Way galaxy, will also open new opportunities for discovering and monitoring radio transients. The HIRAX correlator will have the ability to rapidly and efficiently detect transient events. This new data will shed light on the poorly understood nature of fast radio bursts (FRBs), enable pulsar monitoring to enhance long-wavelength gravitational wave searches, and provide a rich data set for new radio transient phenomena searches. This paper discusses the HIRAX instrument, science goals, and current status.

Fate of a neutron star with an endoparasitic black hole and implications for dark matter

“…Energetically, such events are plausible sources for FRBs, and even short gamma-ray bursts, which would be unaccompanied by a kilonova. New observatories like CHIME [34], HIRAX [35], SKA [36], FAST [37], and others are rapidly increasing the number of observed FRBs, and providing crucial clues to their source(s). Upcoming radio surveys will also take a more accurate census of the pulsar population in the galactic core, which will place bounds on, or provide evidence for, the scenario studied here.…”

Forecast for FAST: from galaxies survey to intensity mapping

“…In more general context, Chang et al (2008) studied this mode of observation and named it the intensity mapping method, and also proposed that a cost-effective way to survey large scale structure is to develop a dedicated dense array of cylinder or small dish antennas (Chang et al 2008;Ansari et al 2008;Seo et al 2010;Ansari et al 2012). Indeed a number of such small-to-mid scale experiments are undergoing, such as those of Tianlai (Chen 2012;Xu et al 2015), CHIME (Bandura et al 2014) and HIRAX (Newburgh et al 2016), as well as the specially designed single dish experiment BINGO (Battye et al 2012(Battye et al , 2016.…”

Design, operation and performance of the PAON4 prototype transit interferometer

“…CHIME (Bandura et al 2014), which is among the most advanced IM projects, uses an array of cylinders, as pioneered by the Pittsburgh Cylindrical Telescope (PCT) prototype (Bandura 2011). The HIRAX project (Newburgh et al 2016) plans to build a large array of 6 meter dishes, in South Africa, close to the SKA site, and larger arrays, such as the proposed PUMA are being considered (Bandura et al 2019).…”