J/MNRAS/436/1286 Cen A 118MHz MWA image (McKinley+, 2013)
The giant lobes of Centaurus a observed at 118MHz with the
Murchison widefield array.
McKinley B., Briggs F., Gaensler B.M., Feain I.J., Bernardi G., Wayth R.B.,
Johnston-Hollitt M., Offringa A.R., Arcus W., Barnes D.G., Bowman J.D.,
Bunton J.D., Cappallo R.J., Corey B.E., Deshpande A.A., Desouza L.,
Emrich D., Goeke R., Greenhill L.J., Hazelton B.J., Herne D., Hewitt J.N.,
Kaplan D.L., Kasper J.C., Kincaid B.B., Koenig R., Kratzenberg E.,
Lonsdale C.J., Lynch M.J., Mcwhirter S.R., Mitchell D.A., Morales M.F.,
Morgan E., Oberoi D., Ord S.M., Pathikulangara J., Prabu T.,
Remillard R.A., Rogers A.E.E., Roshi D.A., Salah J.E., Sault R.J.,
Udaya Shankar N., Srivani K.S., Stevens J., Subrahmanyan R., Tingay S.J.,
Waterson M., Webster R.L., Whitney A.R., Williams A., Williams C.L.,
Wyithe J.S.B.
<Mon. Not. R. Astron. Soc., 436, 1286-1301 (2013)>
=2013MNRAS.436.1286M 2013MNRAS.436.1286M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio
Keywords: techniques: interferometric - galaxies: active -
galaxies: individual: NGC 5128 - radio continuum: galaxies
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
1.4GHz maps of Cen A and compute spectral indices using
temperature-temperature plots and spectral tomography. We find that
the morphologies at 118MHz and 1.4GHz match very closely apart from an
extra peak in the southern lobe at 118MHz, 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 80Myr.
Description:
The MWA 32T was a scaled-down prototype version of the MWA, consisting
of 32 antenna tiles, each tile consisting of 16 crossed-dipole
antennas above a conducting mesh ground plane. The prototype was
operated over the period 2007 September to 2011 September within the
radio-quiet Murchison Radio Observatory in Western Australia at a
latitude of -26.7°. Cen A was observed with the MWA 32T over
three consecutive nights from 2011 April 29 to 2011 May 1, using 80-s
snapshot observations scheduled over a wide range of hour angles.
Objects:
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RA (2000) DE Designation(s)
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13 25 27.60 -43 01 09.5 Cen A = NGC 5128
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 178 1 Information on fits image
fits/* . 1 FITS image
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See also:
J/other/NatAs/6.109 : Centaurus A (NGC 5128) 185MHz MWA image (McKinley+, 2022)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 55 A26 "datime" Obs.date Observation date
57- 63 F7.3 MHz Freq Observed frequency
65- 68 I4 Kibyte size Size of FITS file
70- 99 A30 --- FileName Name of FITS file, in subdirectory fits
101-178 A78 --- Title Title of the FITS file
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Acknowledgements:
Ben McKinley, ben.mckinley(at)curtin.edu.au
(End) Patricia Vannier [CDS] 07-Feb-2022