BAORadio: A digital pipeline for radio interferometry and 21 cm mapping of large scale structures

TL;DR

This paper introduces a novel digital pipeline for radio interferometry aimed at 3D mapping of hydrogen in the universe, enabling large-scale structure studies and BAO measurements without detecting individual sources.

Contribution

It presents a new method and system design for radio interferometry that allows 3D HI mapping using a dense array with high bandwidth and sensitivity, without source detection.

Findings

Development of a digital radio interferometry system

Capability to map HI distribution in 3D

Suitable for large field-of-view BAO studies

Abstract

3D mapping of matter distribution in the universe through the 21 cm radio emission of atomic hydrogen HI is a complementary approach to optical surveys for the study of the Large Scale Structures, in particular for measuring the BAO (Baryon Acoustic Oscillation) scale up to redshifts z < 3, and therefore constraining dark energy parameters. We propose a novel method to map the HI mass distribution in three dimensions in radio, without detecting or identifying individual compact sources. This method would require an instrument with a large instantaneous bandwidth (> 100 MHz) and high sensitivity, while a rather modest angular resolution (~ 10 arcmin) should be sufficient. These requirements can be met by a dense interferometric array or a phased array (FPA) in the focal plane of a large primary reflector, representing a total collecting area of a few thousand square meters with few hundred simultaneous beams covering a 20 to 100 square degrees field of view. We describe the development and qualification of an electronic and data processing system for digital radio interferometry and beam forming suitable for such instruments with several hundred receiver elements.