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

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

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 obj...

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Bibliographic Details
Main Authors: Hurley-Walker, N., Johnston-Hollitt, M., Ekers, R., Hunstead, R., Sadler, E., Hindson, L., Hancock, P., Bernardi, G., Bowman, J., Briggs, F., Cappallo, R., Corey, B., Deshpande, A., Emrich, D., Gaensler, B., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Kaplan, D., Kasper, J., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, Mitchell, D., McWhirter, R., Morales, M., Morgan, E., Oberoi, D., Offringa, A., Ord, S., Prabu, T., Rogers, A., Roshi, A., Shankar, U., Srivani, K., Subrahmanyan, R., Tingay, Steven, Waterson, M., Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C.
Format: Journal Article
Published: Oxford University Press 2015
Online Access:http://hdl.handle.net/20.500.11937/33240
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Summary: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.

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