Broad-band Radio Polarimetry of disk galaxies and AGN with KAT 7 [GA]

http://arxiv.org/abs/2011.12592


We report broad-band (1.2 – 1.9 GHz) radio continuum observations at arcminute resolutions of two nearby disk galaxies, NGC 1808 and NGC 1097, and four AGN powered radio sources; PKS B1934-638, PKS B0407-658, J0240-231, and J0538-440. We use Rotation Measure Synthesis to analyze their Faraday complexity. Observations were made with the KAT\,7 radio telescope array, in South Africa. The AGN powered sources fall into two “Faraday” categories — simple and complex. The most polarized sources, J0538-440 and J0240-231, are found to have complex Faraday spectra that can be time variable (J0538-440 case) and also indicative of complex Faraday emitting and rotating components along the line of sight. PKS B0407-658 shows a simple Faraday spectrum while PKS B1934-638 is undetected in polarization. The disk galaxies are classified as complex, albeit at low signal-to-noise. This may indicate depolarization due to turbulence of the magnetised plasma in the bar and circumnuclear regions and/or frequency-dependent depolarization at L-band

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L. Legodi, A. Taylor and J. Stil
Thu, 26 Nov 20
21/65

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