Rotating baryonic dark halos

TL;DR

This paper uses Planck data to detect microwave asymmetries around galaxy M104, revealing complex halo dynamics and supporting a novel method for mapping dark halos in nearby galaxies.

Contribution

It demonstrates a new approach to analyze microwave data for revealing and mapping dark matter halos around galaxies.

Findings

Detected microwave asymmetry consistent with galactic rotation effects.

Found evidence of complex dynamics in M104's dark halo.

Confirmed the effectiveness of the method for nearby edge-on galaxies.

Abstract

Galactic halos are of great importance for our understanding of both the dark matter nature and primordial non-Gaussianity in the perturbation spectrum, a powerful discriminant of the physical mechanisms that generated the cosmological fluctuations observed today. In this paper we analyze {\it Planck} data towards the galaxy M104 (Sombrero) and find an asymmetry in the microwave temperature which extends up to about $1 \degr$ from the galactic center. This frequency-independent asymmetry is consistent with that induced by the Doppler effect due to the galactic rotation and we find a probability of less than about $0.2\%$ that it is due to a random fluctuation of the microwave background. In addition, {\it Planck} data indicate the relatively complex dynamics of the M104 galactic halo, and this appears to be in agreement with previous studies. In view of our previous analysis of the dark halos of nearby galaxies, this finding confirms the efficiency of the method used in revealing and mapping the dark halos around relatively nearby edge-on galaxies.