Elisabetta Memola, Paolo Salucci, Ana Babic
We investigate the distribution of the luminous and the dark matter
components in the isolated ellipticals NGC 7052 and NGC 7785, embedded in an
emitting hot gas halo, by means of relevant X-ray and photometric data. In
order to calculate the dark matter distribution in these rare objects, we
performed an improved X-ray analysis of the XMM-Newton data of NGC 7785, and we
used former results based on Chandra data of NGC 7052. For each object we also
derived the stellar spheroid length scale from the surface photometry and the
spheroid stellar mass from an analysis of the galaxy spectral energy
distribution. We find that a dark matter component is present in these objects.
It is subdominant and mixed with the luminous matter inside the optical region
half-light radius wide, while it dominates the gravitational potential at outer
radii. On the whole, the dark halo structure is very similar to that found
around spirals of comparable luminosity and it is well reproduced by a Burkert
halo, while a Sersic spheroid accounts well for the baryonic component.
View original:
http://arxiv.org/abs/1106.5133
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