Radio observations of supernova remnant G1.9+0.3
Monthly Notices of the Royal Astronomical Society Oxford University Press 492:2 (2019) 2606-2621
Authors:
Kieran J Luken, Miroslav D Filipovic, Nigel I Maxted, Roland Kothes, Ray P Norris, James R Allison, Rebecca Blackwell, Catherine Braiding, Robert Brose, Michael Burton, Ain Y De Horta, Tim J Galvin, Lisa Harvey-Smith, Natasha Hurley-Walker, Denis Leahy, Nicholas O Ralph, Quentin Roper, Gavin Rowell, Iurii Sushch, Dejan Urosevic, Graeme F Wong
Abstract:
We present 1–10 GHz radio continuum flux density, spectral index, polarization, and rotation measure (RM) images of the youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the Australia Telescope Compact Array. We have conducted an expansion study spanning eight epochs between 1984 and 2017, yielding results consistent with previous expansion studies of G1.9+0.3. We find a mean radio continuum expansion rate of (0.78 ± 0.09) per cent yr−1 (or ∼8900 km s−1 at an assumed distance of 8.5 kpc), although the expansion rate varies across the SNR perimetre. In the case of the most recent epoch between 2016 and 2017, we observe faster-than-expected expansion of the northern region. We find a global spectral index for G1.9+0.3 of −0.81 ± 0.02 (76 MHz–10 GHz). Towards the northern region, however, the radio spectrum is observed to steepen significantly (∼−1). Towards the two so-called (east and west) ‘ears’ of G1.9+0.3, we find very different RM values of 400–600 and 100–200 rad m2, respectively. The fractional polarization of the radio continuum emission reaches (19 ± 2) per cent, consistent with other, slightly older, SNRs such as Cas A.
