  The non-Gaussian Cold Spot (CS) surrounded by its hot ring is one of the most
striking features of the CMB. It has been speculated that either new physics or
ISW effect induced by the presence of a cosmic void at high redshift can
account for the observations. Here we investigate if the systematic decrease in
CMB temperature in the neighbourhood of nearby galaxies may create such a
strong temperature depression. In particular, we note that the Eridanus
supergroup and its neighbouring groups, is in the CS area. Our goal is to
analyse observational galaxy data to characterise the neighbourhood of the CS,
explore the properties of these galaxies and thereby make a prediction of the
CMB temperature decrement in this region. We use the Planck SMICA maps and the
galaxy catalogues 2MRS, 6dF and HIPASS as foreground tracers. We apply mean
temperature profiles to model the temperature decrement from the galaxies in
the CS area. Even after correcting for the mean low temperature of the CS
region, we find that the temperature decrement around galaxies is significantly
stronger than the mean decrement in other parts of the sky. We discuss whether
this could be attributed to the fact that the CS area coincides with one of the
regions populated by the most HI deficient galaxies. Modelling the foreground
temperature profile, we find a particularly strong temperature decrement due to
the presence of the late-type overabundant largest group complex in the nearby
universe. A CS shape, which to a large degree overlaps with the CMB CS, is
observed. We conclude that the coincidence of the only nearby spiral rich group
complex located in the CS region, and the success of the modelling performed,
adds strong evidence to the existence of a local extragalactic foreground which
could account for the observed temperature depression, alleviating the tension
with an otherwise Gaussian field expected in the CMB.
