The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array

McKinley, B; Briggs, F; Gaensler, BM; Feain, IJ; Bernardi, G; Wayth, RB; Johnston-Hollitt, M; Offringa, AR; Arcus, W; Barnes, DG; Bowman, JD; Bunton, JD; Cappallo, RJ; Corey, BE; Deshpande, AA; deSouza, L; Emrich, D; Goeke, R; Greenhill, LJ; Hazelton, BJ; Herne, D; Hewitt, JN; Kaplan, DL; Kasper, JC; Kincaid, BB; Koenig, R; Kratzenberg, E; Lonsdale, CJ; Lynch, MJ; McWhirter, SR; Mitchell, DA; Morales, MF; Morgan, E; Oberoi, D; Ord, SM; Pathikulangara, J; Prabu, T; Remillard, RA; Rogers, AEE; Roshi, DA; Salah, JE; Sault, RJ; Udaya Shankar, N; Srivani, KS; Stevens, J; Subrahmanyan, R; Tingay, SJ; Waterson, M; Webster, RL; Whitney, AR; Williams, A; Williams, CL; Wyithe, JSB

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The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array

Citation

McKinley, B and Briggs, F and Gaensler, BM and Feain, IJ and Bernardi, G and Wayth, RB and Johnston-Hollitt, M and Offringa, AR and Arcus, W and Barnes, DG and Bowman, JD and Bunton, JD and Cappallo, RJ and Corey, BE and Deshpande, AA and deSouza, L and Emrich, D and Goeke, R and Greenhill, LJ and Hazelton, BJ and Herne, D and Hewitt, JN and Kaplan, DL and Kasper, JC and Kincaid, BB and Koenig, R and Kratzenberg, E and Lonsdale, CJ and Lynch, MJ and McWhirter, SR and Mitchell, DA and Morales, MF and Morgan, E and Oberoi, D and Ord, SM and Pathikulangara, J and Prabu, T and Remillard, RA and Rogers, AEE and Roshi, DA and Salah, JE and Sault, RJ and Udaya Shankar, N and Srivani, KS and Stevens, J and Subrahmanyan, R and Tingay, SJ and Waterson, M and Webster, RL and Whitney, AR and Williams, A and Williams, CL and Wyithe, JSB, The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array, Monthly Notices of the Royal Astronomical Society, 436, (2) pp. 1286-1301. ISSN 0035-8711 (2013) [Refereed Article]

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DOI: doi:10.1093/mnras/stt1662

Abstract

We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes.We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that the morphologies at 118MHz and 1.4 GHz match very closely apart from an extra peak in the southern lobe at 118 MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that support a value for the lobe age of between 10 and 80 Myr.

Item Details

Item Type:	Refereed Article
Keywords:	techniques: interferometric – galaxies: active – galaxies: individual: NGC 5128 – radio continuum: galaxies
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Cosmology and extragalactic astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Stevens, J (Dr Jamie Stevens)
ID Code:	89210
Year Published:	2013
Web of Science^® Times Cited:	19
Deposited By:	Mathematics and Physics
Deposited On:	2014-02-26
Last Modified:	2014-05-08
Downloads:	390 View Download Statistics

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