Radio observations of supernova remnant G1.9+0.3

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 eigh...

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Veröffentlicht in:Monthly notices of the Royal Astronomical Society 2020-02, Vol.492 (2), p.2606-2621
Hauptverfasser: Luken, Kieran J, Filipović, Miroslav D, Maxted, Nigel I, Kothes, Roland, Norris, Ray P, Allison, James R, Blackwell, Rebecca, Braiding, Catherine, Brose, Robert, Burton, Michael, De Horta, Ain Y, Galvin, Tim J, Harvey-Smith, Lisa, Hurley-Walker, Natasha, Leahy, Denis, Ralph, Nicholas O, Roper, Quentin, Rowell, Gavin, Sushch, Iurii, Urošević, Dejan, Wong, Graeme F
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Sprache:eng
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Zusammenfassung: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.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stz3439