Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array

Abstract

Recent observations with the Murchison Widefield Array at 185~MHz have serendipitously unveiled a heretofore unknown giant and relatively nearby ($z=0.0178$) radio galaxy associated with NGC\,1534. The diffuse emission presented here is the first indication that NGC\,1534 is one of a rare class of objects (along with NGC\,5128 and NGC\,612) in which a galaxy with a prominent dust lane hosts radio emission on scales of $\sim$700\,kpc. We present details of the radio emission along with a detailed comparison with other radio galaxies with disks. NGC1534 is the lowest surface brightness radio galaxy known with an estimated scaled 1.4-GHz surface brightness of just 0.2\,mJy\,arcmin${}^{-2}$. The radio lobes have one of the steepest spectral indices yet observed: $\alpha =-2.1\pm 0.1$, and the core to lobe luminosity ratio is $<0.1$\%. We estimate the space density of this low brightness (dying) phase of radio galaxy evolution as $7\times 10^{-7}$\,Mpc${}^{-3}$ and argue that normal AGN cannot spend more than 6\% of their lifetime in this phase if they all go through the same cycle.

12 pages, 7 figures, accepted MNRAS

References in corpus (5)

• Radio sources in the 6dFGS: Local luminosity functions at 1.4 GHz for star-forming galaxies and radio-loud AGN
• Mega parsec relativistic jets launched from an accreting supermassive blackhole in an extreme spiral galaxy
• The first Murchison Widefield Array low frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667
• Enormous disc of cool gas surrounding the nearby powerful radio galaxy NGC 612 (PKS 0131-36)
• A new search for distant radio galaxies in the southern hemisphere - I. Sample definition and radio properties

Cited by in corpus (12)

• MIGHTEE: Are giant radio galaxies more common than we thought?
• Science with the Murchison Widefield Array: Phase I Results and Phase II Opportunities
• A High Reliability Survey of Discrete Epoch of Reionization Foreground Sources in the MWA EoR0 Field
• The best of both worlds: Combining LOFAR and Apertif to derive resolved radio spectral index images
• Multi-frequency characterisation of remnant radio galaxies in the Lockman Hole field
• The GLEAM 4-Jy (G4Jy) Sample: I. Definition and the catalogue
• The Dynamics and Energetics of Remnant and Restarting RLAGN
• Hard X-ray selected giant radio galaxies -- III. The LOFAR view
• J1615+5452: a remnant radio galaxy in the ELAIS-N1 field
• A new catalogue of head-tail radio galaxies from LoTSS DR1
• Revealing the Unusual Structure of the KAT-7-Discovered Giant Radio Galaxy J0133$-$1302
• Multifrequency analysis of the radio emission from a post-merger galaxy CGCG 292-057