Issue |
A&A
Volume 508, Number 2, December III 2009
|
|
---|---|---|
Page(s) | 603 - 614 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/200913021 | |
Published online | 27 October 2009 |
Radio and spectroscopic properties of miniature radio galaxies: revealing the bulk of the radio-loud AGN population*
1
Universitá di Torino, via P. Giuria 1, 10125 Torino, Italy e-mail: baldi@oato.inaf.it
2
INAF – Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Italy e-mail: capetti@oato.inaf.it
Received:
30
July
2009
Accepted:
22
September
2009
We explore radio and spectroscopic properties of a sample of 14
miniature radio galaxies, i.e. early-type core galaxies hosting radio-loud
AGN of extremely low radio power, 1027-29 erg s-1 Hz-1 at 1.4
GHz.
Miniature radio galaxies smoothly extend the relationships found for the
more powerful FR I radio galaxies between emission line, optical and radio
nuclear luminosities to lower levels. However, they have a deficit of a
factor of ~100 in extended radio emission with respect to that of the
classical example of 3CR/FR I. This is not due to their low luminosity,
since we found radio galaxies of higher radio core power, similar to those
of 3CR/FR I, showing the same behavior, i.e. lacking significant extended
radio emission. Such sources form the bulk of the population of radio-loud
AGN in the Sloan Digital Sky Survey. At a given level of nuclear emission,
one can find radio sources with an extremely wide range, a factor of
100, of radio power.
We argue that the prevalence of sources with luminous extended radio
structures in flux limited samples is due to a selection bias, since the
inclusion of such objects is highly favored. The most studied catalogues of
radio galaxies are thus composed by the minority of radio-loud AGN that meet
the physical conditions required to form extended radio sources, while the
bulk of the population is virtually unexplored.
Key words: galaxies: active / galaxies: elliptical and lenticular, cD / galaxies: nuclei / galaxies: jets / galaxies: evolution
© ESO, 2009
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