IGM Heating in Fossil Galaxy Groups
  We study intergalactic medium (IGM) heating in a sample of five fossil galaxy
groups by using their radio properties at 610 MHz and 1.4 GHz. The power by
radio jets introducing mechanical heating for the sampled objects is not
sufficient enough to suppress the cooling flow. Therefore, we discussed shock-,
vortex heating, and conduction as alternative heating processes. Further, the
1.4 GHz and 610 MHz radio luminosities of fossil groups are compared to a
sample of normal galaxy groups of the same radio brightest (BGGs), stellar
mass, and total group stellar mass, quantified using the $K$-band luminosity.
It appears that the fossil BGGs are under luminous at 1.4 GHz and 610 MHz for a
given BGG stellar mass and luminosity, in comparison to a general population of
the groups. In addition, we explore how the bolometric radio luminosity of
fossil sample depends on clusters and groups characteristics. Using the HIghest
X-ray FLUx Galaxy Cluster Sample (HIFLUGCS) as a control sample we found that
the large-scale behaviours of fossil galaxy groups are consistent with their
relaxed and virialised nature.
