A&A 468, 803-805 (2007)
DOI: 10.1051/0004-6361:20077372
Jeans instability of a galactic disk embedded in a live dark halo
O. Esquivel and B. FuchsAstronomisches Rechen-Institut am Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, 69120 Heidelberg, Germany
e-mail: esquivel@ari.uni-heidelberg.de
(Received 28 February 2007 / Accepted 3 April 2007)
Abstract
We investigate the Jeans instability of a galactic disk embedded in
a dynamically responsive dark halo. It is shown that the disk-halo system
becomes nominally Jeans unstable. On small scales the instability is
suppressed, if the Toomre stability index
is higher than a certain
threshold, but on large scales the Jeans instability sets invariably in.
However, using a simple self-consistent disk-halo model it is demonstrated
that this occurs on scales which are much larger than the system
so that this is indeed only a nominal effect. From a practical point of view
the Jeans instability of galactic disks is not affected by a live dark halo.
Key words: galaxies: kinematics and dynamics -- galaxies: halos
© ESO 2007

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