  We investigate the density of states for a photon gas confined in a
nonmagnetic metamaterial medium in which some components of the permittivity
tensor are negative. We study the effect of the resulting hyperbolic dispersion
relations on the black body spectral density. We show that for both of the
possible wavevector space topologies, the spectral density vanishes at a
certain frequency. We obtain the partition function and derive some
thermodynamical quantities of the system. To leading order, the results
resemble those of a one- or two-dimensional photon gas with an enhanced density
of states.
