Improvements to the Search for Cosmic Dawn Using the Long Wavelength Array

TL;DR

This paper reports advancements in detecting the Cosmic Dawn signal using the Long Wavelength Array, including improved methods, hardware, and a novel beamforming technique, resulting in more sensitive observations that approach the expected signal levels.

Contribution

It introduces a new achromatic beamforming technique and enhanced calibration and modeling methods, significantly improving the sensitivity of LWA-SV for Cosmic Dawn detection.

Findings

Residual RMS limits are six times above the EDGES signal amplitude.

29 days of observations conducted in March-April 2021.

Methodological and hardware improvements enhanced detection sensitivity.

Abstract

We present recent improvements to the search for the global Cosmic Dawn signature using the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA-SV). These improvements are both in the methodology of the experiment and the hardware of the station. An improved observing strategy along with more sophisticated temperature calibration and foreground modelling schemes have led to improved residual RMS limits. A large improvement over previous work using LWA-SV is the use of a novel achromatic beamforming technique which has been developed for LWA-SV. We present results from an observing campaign which contains 29 days of observations between March $10^{\rm{th}}$, 2021 and April $10^{\rm{th}}$ 2021. The reported residual RMS limits are 6 times above the amplitude of the potential signal reported by the Experiment to Detect the Global EoR Signature (EDGES) collaboration.