  Previous experimental and theoretical evidence has shown that convective flow
may appear in granular fluids if subjected to a thermal gradient and gravity
(Rayleigh-B\'enard-type convection). In contrast to this, we present here
evidence of gravity-free thermal convection in a granular gas, with no presence
of external thermal gradients either. Convection is here maintained steady by
internal gradients due to dissipation and thermal sources at the same
temperature. The granular gas is composed by identical disks and is enclosed in
a rectangular region. Our results are obtained by means of an event-driven
algorithm for inelastic hard disks.
