Messier 81’s Planck view versus its halo mapping

¹ Center for Cosmology and Astrophysics, Alikhanian National Laboratory and Yerevan State University, 0036 Yerevan, Armenia
e-mail: depaolis@le.infn.it
² SIA, Sapienza University of Rome, 00185 Rome, Italy
³ Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, via per Arnesano, 73100 Lecce, Italy
⁴ INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce, Italy
⁵ Department of Physics, School of Natural Sciences, National University of Sciences and Technology, 44000 Islamabad, Pakistan
⁶ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
⁷ Department of Physics, University of Trento, 38123 Povo, Trento, Italy and TIFPA/INFN, 38123 Povo, Italy

Received: 6 August 2017
Accepted: 3 October 2017

Abstract

This paper is a follow-up of a previous paper about the M 82 galaxy and its halo based on Planck observations. As in the case of M 82, a substantial north-south and east-west temperature asymmetry is also found for the M 81 galaxy, extending up to galactocentric distances of about 1.5°. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M 81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M 81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the cosmic microwave background 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.