  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.
