University of Hertfordshire

From the same journal

From the same journal

By the same authors

Unveiling the cause of hybrid morphology radio sources (HyMoRS)

Research output: Contribution to journalArticle

Documents

View graph of relations
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Journal publication date29 Oct 2019
Early online date29 Oct 2019
Publication statusE-pub ahead of print - 29 Oct 2019

Abstract

Hybrid morphology radio sources (HyMoRS) are a rare group of radio galaxies in which differing Fanaroff & Riley morphologies (FR I/II) are observed for each of the two lobes. While they potentially provide insights into the formation of lobe structure, particle acceleration, and the FR dichotomy, previous work on HyMoRS has mainly been limited to low-resolution studies, searches for new candidates, and milliarcsecond-scale VLBI observations of the core region. In this paper, we use new multi-array configuration Very Large Array (VLA) observations between 1 and 8 GHz to determine the morphology of HyMoRS on arcsecond scales and perform the first well-resolved spectral study of these unusual sources. We find that while the apparent FR I lobe is centre-brightened, this is the result of a compact acceleration region resembling a hotspot with a spectrum more consistent with an FR II ("strong-flavour") jet. We find that the spectra of the apparent FR I lobes are not similar to their classical counterparts and are likely the result of line-of-sight mixing of plasma across a range of spectral ages. We consider possible mechanisms that could lead to the formation of HyMoRS under such conditions, including environment asymmetry and restarted sources, concluding through the use of simple modelling that HyMoRS are the result of orientation effects on intrinsically FR II sources with lobes non-parallel to the inner jet.

Notes

19 pages, 4 figures, 6 tables. Accepted for publication in MNRAS

ID: 17626333