Search for hybrid morphology radio galaxies from FIRST survey at 1400 MHz

TL;DR

This study systematically searched for hybrid morphology radio galaxies in the FIRST survey at 1400 MHz, significantly increasing the known sample and providing insights into jet interactions and the FR dichotomy.

Contribution

It is the first large-scale systematic search for HyMoRS in the FIRST survey, expanding the sample size and analyzing their properties.

Findings

Identified 33 candidate HyMoRS, increasing known sample size.

Estimated spectral indices and radio luminosities for the cataloged sources.

Discovered the most luminous and farthest HyMoRS in the sample.

Abstract

Hybrid Morphology Radio Sources (HyMoRS) are a very rare subclass of radio galaxies with apparent mixed FR morphology, i.e. these galaxies seem to have an FR-I structure on one side of the core and an FR-II structure on the other side of the core. We systematically searched for HyMoRS using Very Large Array (VLA) Faint Images of the Radio Sky at Twenty-cm (FIRST) survey with 1400 MHz frequency and identified 33 candidate HyMoRS. Our finding significantly increased the known sample size of HyMoRS. HyMoRS may play an essential role in understanding the interaction of jets with the interstellar medium and the much-debated topic of the FR dichotomy. We identified optical counterparts for 29 sources in our catalogue. In our sample of sources, one source (J1106+1355) had quasar-like behaviour. Four sources were BRCLG (Brightest Cluster Galaxies) and six were LRG (Luminous Red Galaxies). We have estimated the spectral index and radio luminosity of HyMoRS in our catalogue, when possible. We found that J1136--0328 was the most luminous source in our sample ($\log L = 27.01$ W Hz$^{-1}$sr$^{-1}$). It was also the farthest HyMoRS (with a redshift $z$ = 0.82) in our sample. With the help of a large sample size of discovered sources, various statistical properties of detected galaxies were studied.