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89210 - The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array.pdf (7 MB)

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

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posted on 2023-05-17, 22:39 authored by 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
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.


Publication title

Monthly Notices of the Royal Astronomical Society








School of Natural Sciences


Blackwell Publishing Ltd

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9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

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Copyright 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

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Expanding knowledge in the physical sciences

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