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Density profiles of galaxy bulges and nuclei

Published online by Cambridge University Press:  19 May 2006

M. Balcells
Affiliation:
Instituto de Astrofsica de Canarias, 38200 La Laguna, Tenerife, Spain
A.W. Graham
Affiliation:
Mount Stromlo and Siding Spring Observatories, Australian National University, Private Bag, Weston Creek, ACT 2611, Australia
R.F. Peletier
Affiliation:
Kapteyn Astronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands
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Abstract

The bulge contribution to the inner density profile of a galaxy is well traced by the bulge's NIR surface brightness profile. We map the surface brightness profiles of bulges using HST/NICMOS imaging. Most bulges show nuclear components of 20–200 pc scales, and frequently also unresolved nuclear star clusters (<20 pc). These nuclear components are the densest parts of bulges, and gave bulges the “reputation” of having high stellar concentration. Actually, the Sérsic r1/n bulges typically have low concentrations, 1 < n < 2.5. We cannot confirm the bi-modal distribution of bulge profile slopes reported by others, and suggest that the alleged bi-modality is related to selectively excluding/including nuclear components in low/high-n bulges.

Type
Research Article
Copyright
© EAS, EDP Sciences, 2006

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