A ground-based 21cm Baryon acoustic oscillation survey

TL;DR

This paper evaluates the potential of ground-based 21cm intensity mapping with a cylindrical radio telescope to measure baryon acoustic oscillations, optimizing survey parameters for competitive dark energy constraints.

Contribution

It introduces a comprehensive analysis of angular resolution effects on BAO measurements and provides an optimization framework for CRT survey design.

Findings

Angular resolution impacts BAO measurement precision.

Optimized CRT survey parameters can rival Stage III dark energy experiments.

A publicly available tool for survey cost and performance estimation.

Abstract

Baryon acoustic oscillations (BAO) provide a robust standard ruler with which to measure the acceleration of the Universe. The BAO feature has so far been detected in optical galaxy surveys. Intensity mapping of neutral hydrogen emission with a ground-based radio telescope provides another promising window for measuring BAO at redshifts of order unity for relatively low cost. While the cylindrical radio telescope (CRT) proposed for these measurements will have excellent redshift resolution, it will suffer from poor angular resolution (a few arcminutes at best). We investigate the effect of angular resolution on the standard ruler test with BAO, using the Dark Energy Task Force Figure of Merit as a benchmark. We then extend the analysis to include variations in the parameters characterizing the telescope and the underlying physics. Finally, we optimize the survey parameters (holding total cost fixed) and present an example of a CRT BAO survey that is competitive with Stage III dark energy experiments. The tools developed here form the backbone of a publicly available code that can be used to obtain estimates of cost and Figure of Merit for any set of parameters.