Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the murchison widefield array

Natasha Hurley-Walker*, Melanie Johnston-Hollitt, Ron Ekers, Richard Hunstead, Elaine M. Sadler, Luke Hindson, Paul Hancock, Gianni Bernardi, Judd D. Bowman, Frank Briggs, Roger Cappallo, Brian Corey, Avinash A. Deshpande, David Emrich, Bryan M. Gaensler, Robert Goeke, Lincoln Greenhill, Bryna J. Hazelton, Jacqueline Hewitt, David L. KaplanJustin Kasper, Eric Kratzenberg, Colin Lonsdale, Mervyn Lynch, Daniel Mitchell, Russell McWhirter, Miguel Morales, Edward Morgan, Divya Oberoi, André Offringa, Stephen Ord, Thiagaraj Prabu, Alan Rogers, Anish Roshi, Udaya Shankar, K. Srivani, Ravi Subrahmanyan, Steven Tingay, Mark Waterson, Randall B. Wayth, Rachel Webster, Alan Whitney, Andrew Williams, Chris Williams

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    31 Citations (Scopus)

    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 ~700 kpc. We present details of the radio emission along with a detailed comparison with other radio galaxies with discs. NGC 1534 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: α = -2.1 ± 0.1, and the core to lobe luminosity ratio is <0.1 per cent. We estimate the space density of this low brightness (dying) phase of radio galaxy evolution as 7 × 10-7 Mpc-3 and argue that normal AGN cannot spend more than 6 per cent of their lifetime in this phase if they all go through the same cycle.

    Original languageEnglish
    Pages (from-to)2468-2478
    Number of pages11
    JournalMonthly Notices of the Royal Astronomical Society
    Volume447
    Issue number3
    DOIs
    Publication statusPublished - 1 Mar 2015

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