A characterization of the diffuse Galactic emissions in the anti-center of the Galaxy

TL;DR

This study analyzes diffuse Galactic emissions in the anti-center region using Archeops and WMAP data, identifying thermal dust, synchrotron, free-free, and anomalous emissions, and highlighting the need for broader frequency data to understand the anomalous component.

Contribution

It provides a detailed characterization of diffuse Galactic emissions in the anti-center region and identifies the presence of anomalous emission with a specific spectral index, highlighting the need for further data.

Findings

Thermal dust spectrum and distribution were precisely inferred.

Residuals at low frequencies cannot be explained by standard synchrotron and free-free emissions.

Evidence for anomalous emission with spectral index 2.5 was found.

Abstract

Using the Archeops and WMAP data we perform a study of the anti-center Galactic diffuse emissions - thermal dust, synchrotron, free-free and anomalous emission - at degree scales. The high frequency data are used to infer the thermal dust electromagnetic spectrum and spatial distribution allowing us to precisely subtract this component at lower frequencies. After subtraction of the thermal dust component a mixture of standard synchrotron and free-free emissions does not account for the residuals at these low frequencies. Including the all-sky 408 MHz Haslam data we find evidences for anomalous emission with a spectral index of 2.5 in TRJ units. However, we are not able to conclude regarding the nature of this anomalous emission in this region. For the purpose, data between 408 MHz and 20 GHz covering the same sky region are needed.