A sample of 25 radio galaxies with highly unusual radio morphologies, selected from the LoTSS-DR2 survey at 144 MHz

Abstract

From a careful visual scrutiny of the radio structures of a well-defined sample of 2428 sources in the LoTSS DR2 survey made at 144 MHz with a 6" beam, we have selected a subset of 25 (i.e., 1%) sources showing highly unusual radio structures, not conforming to the prevalent radio morphological classification. Here we present and briefly discuss the basic properties of these rare morphological outliers and attempt to dissect their morphological peculiarities, based on multi-wavelength radio images and radio-optical overlays. Also, we underscore the need to accord due importance to such anomalous radio sources, considering the challenge they pose to the standard theoretical models and simulations of extragalactic double radio sources.