- [*] Galaxies with a minimum in central stellar luminosity density
- Lauer T.R., Gebhardt K., Richstone D., Tremaine S., Bender R.,
Bower G., Dressler A., Faber S.M., Filippenko A., Green R.,
Grillmair C., Ho L., Kormendy J., Magorrian J., Pinkney J.,
Laine S., Postman M., van der Marel R.P.
- AJ, 124, 1975-1987, 2002
this paper in the ADS
We used Hubble Space Telescope} WFPC2 images to identify six
early-type galaxies with surface-brightness profiles that decrease
inward over a limited range of radii near their centers. The implied
luminosity density profiles of these galaxies have local minima
interior to their core break radii. NGC 3706 harbors a high surface
brightness ring of starlight with a radius of approximately 20 pc.
Its central structure may be related to that in the double-nucleus
galaxies M31 and NGC 4486B. NGC 4406 and NGC 6876 have nearly flat
cores that on close inspection are centrally depressed. Colors for
both galaxies imply that this is not due to dust absorption. The
surface brightness distributions of both galaxies are consistent with
stellar tori that are more diffuse than the sharply defined system in
NGC 3706. The remaining three galaxies are the brightest cluster
galaxies in A260, A347, and A3574. Color information is not available
for these objects, but they strongly resemble NGC 4406 and NGC 6876 in
their cores. The thin ring in NGC 3706 may have formed dissipatively.
The five other galaxies resemble the endpoints of some simulations of
the merging of two gas-free stellar systems, each harboring a massive
nuclear black hole. In one version of this scenario, diffuse stellar
tori are produced when stars initially bound to one black hole are
tidally stripped away by the second black hole. Alternatively, some
inward-decreasing surface-brightness profiles may reflect the ejection
of stars from a core during the hardening of the binary black hole
created during the merger.
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Last modified November 29, 2002.
Roeland van der Marel,