Messier 81's Planck view vs its halo mapping

TL;DR

This study uses Planck data to analyze the temperature asymmetry in M81's halo, revealing Doppler effects related to halo rotation and galaxy interactions, demonstrating a new method for mapping galactic haloes.

Contribution

It introduces the use of CMB temperature asymmetry as a direct tool to map galactic haloes and intergalactic bridges, extending previous work on M82 to M81.

Findings

Detected significant temperature asymmetry in M81's halo.

Temperature asymmetry is frequency-independent, indicating a Doppler effect.

Method proves effective for mapping galactic haloes and intergalactic structures.

Abstract

This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-South and East-West temperature asymmetry is found, extending up to galactocentric distances of about $1.5^\circ$. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the CMB temperature asymmetry method thus is shown to act as a direct tool to map the galactic haloes and/or the intergalactic bridges, invisible in other bands or by other methods.