Falcke & Biermann 1996: Jet/Disk Symbiosis III.
The jet/disk symbiosis III.
What the radio cores in GRS
1915+105, NGC 4258, M81, and Sgr A* tell us about accreting black
Heino Falcke & Peter L. Biermann
Max-Planck-Institut für Radioastronomie, Auf den Hüugel 69, D-53121 Bonn, Germany
to appear in Astronomy & Astrophysics (1999)
We have derived simplified equations for a freely expanding, pressure
driven jet model as a function of jet power and applied it
successfully to the radio cores in the black hole candidates
GRS 1915+105, NGC 4258, and M81 which are observationally well defined
systems, and to Sgr A*. By using equipartition assumptions, the model
has virtually no free parameters and can explain all sources by just
scaling the jet power. In GRS 1915+105 it also naturally explains the
jet velocity and the radio time delay. The jet powers we derive for
the radio cores of the first three sources are comparable to their
accretion disk luminosities, providing further evidence for the
existence of symbiotic jet/disk systems and a common engine mechanism
also in low-luminosity AGN and stellar mass black holes. With the
exception of Sgr A* an advection dominated accretion flow (ADAF) does
not seem to be necessary to explain any of the radio cores which span
a large range in luminosity and size, as well as in black hole masses
and accretion rate---from Eddington to extreme sub-Eddington. We
suggest, however, that the jet model can be used to derive minimum
accretion rates and thus find that Sgr A* seems to be truly
radiatively deficient---even in a starved black hole model---and that
a combination of jet and ADAF model may be one possible solution.
The paper is available in [(laa)LaTeX, PS] format.
Other publications can be found here.
Questions: Heino Falcke, firstname.lastname@example.org