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

Hurley-Walker, Natasha ; Johnston-Hollitt, Melanie ; Ekers, Ron ; Hunstead, Richard ; Sadler, Elaine M. ; Hindson, Luke ; Hancock, Paul ; Bernardi, Gianni ; Bowman, Judd D. ; Briggs, Frank ; Cappallo, Roger ; Corey, Brian ; Deshpande, Avinash A. ; Emrich, David ; Gaensler, Bryan M. ; Goeke, Robert ; Greenhill, Lincoln ; Hazelton, Bryna J. ; Hewitt, Jacqueline ; Kaplan, David L. ; Kasper, Justin ; Kratzenberg, Eric ; Lonsdale, Colin ; Lynch, Mervyn ; Mitchell, Daniel ; McWhirter, Russell ; Morales, Miguel ; Morgan, Edward ; Oberoi, Divya ; Offringa, André ; Ord, Stephen ; Prabu, Thiagaraj ; Rogers, Alan ; Roshi, Anish ; Shankar, Udaya ; Srivani, K. ; Subrahmanyan, Ravi ; Tingay, Steven ; Waterson, Mark ; Wayth, Randall B. ; Webster, Rachel ; Whitney, Alan ; Williams, Andrew ; Williams, Chris (2015) Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array Monthly Notices of the Royal Astronomical Society, 447 (3). pp. 2468-2478. ISSN 0035-8711

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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%. 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% of their lifetime in this phase if they all go through the same cycle.

Item Type:Article
Source:Copyright of this article belongs to Oxford University Press.
Keywords:Techniques: Interferometric; Galaxies: Active; Galaxies: General; Galaxies: Individual:NGC 1534; Radio Continuum: Galaxies
ID Code:114344
Deposited On:21 May 2018 08:49
Last Modified:21 May 2018 08:49

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