A model of diffuse Galactic Radio Emission from 10 MHz to 100 GHz

TL;DR

This paper develops a comprehensive model of diffuse Galactic radio emission across 10 MHz to 100 GHz, aiding cosmological studies by providing accurate foreground predictions and reducing contamination in measurements.

Contribution

It introduces a new global sky model based on extensive radio survey data, including the Villa Elisa data, with a simple three-component principal model fitting multiple datasets with high accuracy.

Findings

A three-component model fits data with 1%-10% accuracy.

The model covers frequencies from 10 MHz to 100 GHz.

Publicly available software and maps facilitate future research.

Abstract

Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. Cosmic Microwave Background experiments have focused on frequencies > 10 GHz, whereas 21 cm tomography of the high redshift universe will mainly focus on < 0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.4 GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multi-frequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 & 408 MHz and 1.4, 2.3, 23, 33, 41, 61, 94 GHz) to an accuracy around 1%-10% depending on frequency and sky region. Both our data compilation and our software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at http://space.mit.edu/home/angelica/gsm .