S. Nandi^1,2 and D. J. Saikia^3,4
1Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital, 263 129, India
²Department of Physics, Kumaun University, Nainital 263 001, India
³ National Centre for Radio Astrophysics, TIFR, Pune University Campus, Post Bag 3, Pune 411 007, India
⁴ Cotton College State University, Panbazar, Guwahati 781 001, India

Abstract. The radio structures and optical identifications of a sample of 242 sources classified as double-double radio sources by Proctor (2011) from a morphological study of sources in the FIRST (Faint Images of the Radio Sky at Twenty centime- ters) survey (2003 April release, 811,117 entries) have been examined. We have been able to confirm only 23 of these as likely to be double-double radio galaxies (DDRGs), whose structures could be attributed to episodic nuclear activity in their host galaxies. A further 63 require either higher-resolution radio observations or optical identifica- tions to determine whether these are DDRGs. The remaining sources are unlikely to be DDRGs. We have examined the luminosities, sizes and symmetry parameters of the DDRGs and the constraints these place on our understanding of these sources.

Keywords: galaxies: active – galaxies: jets – galaxies: nuclei – radio continuum: galaxies

Download Full Paper

Back to Home Page