Volume 527, March 2011
|Number of page(s)||4|
|Published online||27 January 2011|
Letter to the Editor
An optical spectroscopic survey of the 3CR sample of radio galaxies with z < 0.3
IV. Discovery of the new spectroscopic class of relic radio galaxies⋆
INAF - Osservatorio Astronomico di Torino, Strada Osservatorio
2 INAF - Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
3 School of Mathematical and Physical Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK
4 Department of Physics, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623, USA
5 SISSA-ISAS, via Bonomea 265, 34136 Trieste, Italy
6 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
7 INAF - Istituto di Radio Astronomia, via P. Gobetti 101, 40129 Bologna, Italy
Received: 29 October 2010
Accepted: 3 January 2011
From an optical spectroscopic survey of 3CR radio galaxies with z < 0.3, we discovered a new spectroscopic class of powerful radio-loud AGN. The defining characteristics of these galaxies are that compared with radio galaxies of similar radio luminosity they have: a [O III] /Hβ ratio of ~0.5, indicative of an extremely low level of gas excitation; a large deficit of [O III] emission; and radio core power. We interpret these objects as relic AGN, i.e. sources that experienced a large drop in their level of nuclear activity, causing a decrease in their nuclear and line luminosity. This class opens a novel approach to investigating lifetimes and duty cycles of AGN.
Key words: galaxies: active / galaxies: jets / galaxies: elliptical and lenticular, cD
© ESO, 2011
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.