AAS 203rd Meeting, January 2004
Session 116 Elliptical and Spiral Galaxies
Poster, Thursday, January 8, 2004, 9:20am-4:00pm, Grand Hall

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[116.16] Evidence From Surface Brightness Profiles for the Dissipative Merger Formation of Low-Luminosity Elliptical Galaxies

D.B. Fisher, J. Kormendy (University of Texas at Austin), R. Bender (Universitäts-Sternwarte München and Max-Planck Institut für extraterrestrische Physik)

Elliptical galaxies show a well known dichotomy between core and power-law density profiles. Cores are thought to form when binary supermassive black holes, originating in galaxy mergers, decay by flinging stars out of the central regions. In contrast, we have no well formulated theory of the formation of power law density distributions. This is partly because the profiles are thought to be featureless, making interpretation difficult. At large radii, power law galaxies are in fact well fitted by Sérsic functions, log[I(r)] \propto r1/n. However, Kormendy (1999, in ``Galaxy Dynamics'', ed. Merritt et al., San Francisco: ASP, 124) shows that three low luminosity elliptical galaxies have extra light at small radii above the inward extrapolation of Sérsic functions fitted to the outer parts. Their density profiles resemble those produced in dissipative merger simulations by Mihos & Hernquist (1994, ApJ, 437, L47) when gas sinks to the center of the merger remnant and fuels a starburst. In this paper, we present additional galaxies that show similar upward deviations from Sérsic function fits. These objects confirm that the profiles seen in Kormendy (1999) are a common phenomenon in power-law ellipticals. The extra light component is spatially resolved; that is, it is larger than a typical nuclear star cluster (a ``nucleus''). We interpret these profiles as signatures of the formation of low-luminosity ellipticals via dissipative mergers that included central starbursts.

The author(s) of this abstract have provided an email address for comments about the abstract: twitch@astro.as.utexas.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.