Issue |
A&A
Volume 379, Number 1, November III 2001
|
|
---|---|---|
Page(s) | L1 - L4 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20011338 | |
Published online | 15 November 2001 |
The dividing line between FR I and FR II radio-galaxies
1
Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy
2
SISSA/ISAS, via Beirut 2-4, 34014 Trieste, Italy
Corresponding author: G. Ghisellini, gabriele@merate.mi.astro.it
Received:
2
July
2001
Accepted:
18
July
2001
In the radio -host galaxy optical luminosity plane
FR I and FR II radio-galaxies are clearly divided.
Since the optical luminosity of an elliptical galaxy is an indication
of the mass of its central black hole, we propose that the
FR I-FR II dividing luminosity is a function of the mass of the
black hole powering the active nucleus.
Furthermore, as the radio power gives an estimate of the total kinetic power
carried by the jet, the FR I-FR II separation can be re-interpreted as
occurring
at a constant ratio between the jet power and the black hole mass.
There is also convincing evidence of a correlation between the radio
power and the luminosity in narrow emission lines. As the latter
results from photoionization by the radiation produced by accretion, we
can estimate the ionizing luminosity and find that the separation
luminosity can be also re-expressed as a constant accretion rate
between -10-3 of the Eddington one.
This possibly regulates the accretion mode and the consequent
presence and characteristics of nuclear outflows.
Key words: galaxies: jets / galaxies: nuclei / radio continuum: galaxies
© ESO, 2001
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