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Advances in AstronomyVolume 2012 2012, Article ID 709038, 13 pages

Research Article

European Southern Observatory, Karl-Schwarzschild Straβe 2, 85748 Garching bei München, Germany

Excellence Cluster Universe, Boltzmann Straβe 2, 85748 Garching bei München, Germany

Leibniz-Institut für Astrophysik Potsdam AIP, An der Sternwarte 16, 14482 Potsdam, Germany

Received 15 August 2011; Revised 17 November 2011; Accepted 27 November 2011

Academic Editor: Francesca Civano

Copyright © 2012 Nadine Neumayer and C. Jakob Walcher. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 10

, if any. We also derive new upper limits for nuclear star cluster masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following. 1 The - relation cannot flatten at low masses, but may steepen. 2 The - relation may well flatten in contrast. 3 The -Sersic relation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in the -Sersic relation seem to be dwarf elliptical galaxies. When plotting versus we find three different regimes: a nuclear cluster dominated nuclei, b a transition region, and c black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratio - grows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.

Author: Nadine Neumayer and C. Jakob Walcher



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