  We investigate here the thermal properties of accretion disks in a spacetime
for some galactic density profiles in spherical symmetry. The matter
distributions have a finite outer radius with a naked central singularity. The
luminosities of the accretion disks for some density profile models are found
to be higher than those for a Schwarzschild black hole of the same mass. The
slopes for the luminosity distributions with respect to frequencies are
significantly different, especially at higher frequencies, from that in the
Schwarzschild black hole case. Such features may be used to distinguish black
holes from naked singularities. The efficiencies for the conversion of the mass
energy of the accreting gas into radiation and the strength of naked
singularities are analyzed. The novel feature that we find is, the strength of
the singularity is different depending on the profiles considered, and the
stronger the singularity is, the higher is the efficiency for the accretion
disk.
