Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array
Author(s)Cappallo, Roger J.; Corey, Brian E.; Goeke, Robert F.; Kratzenberg, Eric W.; Lonsdale, Colin John; McWhirter, Stephen R.; Rogers, Alan E. E.; Whitney, Alan R.; Hewitt, Jacqueline N.; Morgan, Edward H.; Williams, Christopher Leigh; ... Show more Show less
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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[superscript −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[superscript −7] Mpc[superscript −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.
DepartmentHaystack Observatory; MIT Kavli Institute for Astrophysics and Space Research
Monthly Notices of the Royal Astronomical Society
Oxford University Press
Hurley-Walker, N., M. Johnston-Hollitt, R. Ekers, R. Hunstead, E. M. Sadler, L. Hindson, P. Hancock, et al. “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, no. 3 (January 5, 2015): 2468–2478.
Author's final manuscript