The LWA1 Low Frequency Sky Survey

TL;DR

This paper presents a comprehensive low-frequency radio sky survey from the LWA1 station, providing high-resolution maps and an updated model of diffuse Galactic emission crucial for studying cosmic reionization and the dark ages.

Contribution

It offers the first systematic, high-resolution survey of the sky at 35-80 MHz, improving models of Galactic emission and foregrounds for cosmological studies.

Findings

Maps at nine frequencies between 35 and 80 MHz covering the northern sky.

An updated low-frequency sky model incorporating free-free absorption effects.

Enhanced understanding of Galactic foregrounds for 21 cm cosmology.

Abstract

We present a survey of the radio sky accessible from the first station of the Long Wavelength Array (LWA1). Images are presented at nine frequencies between 35 and 80 MHz with spatial resolutions ranging from $4.7^\circ$ to $2.0^\circ$, respectively. The maps cover the sky north of a declination of $-40^\circ$ and represent the most modern systematic survey of the diffuse Galactic emission within this frequency range. We also combine our survey with other low frequency sky maps to create an updated model of the low frequency sky. Due to the low frequencies probed by our survey, the updated model better accounts for the effects of free-free absorption from Galactic ionized Hydrogen. A longer term motivation behind this survey is to understand the foreground emission that obscures the redshifted 21 cm transition of neutral hydrogen from the cosmic dark ages ($z>10$) and, at higher frequencies, the epoch of reionization ($z>6$).