Understanding the nature of FR II optical nuclei: A new diagnostic plane for radio galaxies

  title={Understanding the nature of FR II optical nuclei: A new diagnostic plane for radio galaxies},
  author={Marco Chiaberge and Alessandro Capetti and Annalisa Celotti},
  journal={Astronomy and Astrophysics},
We extend our study of the nuclei of 3CR FR II radio galaxies through HST optical images up to z= 0:3. In the majority of them an unresolved nucleus (central compact core, CCC) is found. We analyze their position in the plane formed by the radio and optical nuclear luminosities in relation to their optical spectral properties. The broad-lined objects (BLO) have the brightest nuclei: they are present only at optical luminositiesL > 410 42 erg s 1 which we suggest might represent a threshold in… 

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