The radio spectrum and magnetic field structure of SNR HB3

Abstract

Evidence for a spectral flattening of the supernova remnant (SNR) HB3 (G132.7+1.3) was recently claimed in literature based on previously published total flux density data, and the flattening was further interpreted as the discovery of thermal bremsstrahlung emission in the shell of HB3. A spectral flattening has never been observed from any SNR before. Reliable observations of HB3 at frequencies above 3000 MHz are crucial to confirm such a spectral behaviour. We extracted 4800 MHz total intensity and polarisation data of HB3 from the Sino-German 6 cm polarisation survey of the Galactic plane made with the Urumqi 25 m telescope, and analysed the spectrum of HB3, together with Effelsberg data at 1408 MHz and 2675 MHz. We found an overall spectral index of HB3 of alpha=-0.61+-0.06 between 1408 MHz and 4800 MHz, similar to the index at lower frequencies. There is no spectral flattening at high frequencies. We detected strong polarised emission from HB3 at 4800 MHz. Our 4800 MHz data show a tangential field orientation in the HB3 shell.

arXiv comment5 pages. Published by A&A. New 11cm data used. Uncertainty on spectrum is reduced! Match the published text

References in corpus (8)

• The Distance to the Perseus Spiral Arm in the Milky Way
• Pulsar rotation measures and the magnetic structure of our Galaxy
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Cited by in corpus (10)

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• A Systematic Survey for Broadened CO Emission Toward Galactic Supernova Remnants
• A Sino-German $\lambda$6\ cm polarization survey of the Galactic plane. V. Large supernova remnants
• On the supernova remnants with flat radio spectra
• A Sino-German $\lambda$6\ cm polarization survey of the Galactic plane VI. Discovery of supernova remnants G178.2-4.2 and G25.1-2.3
• New 6cm and 11cm observations of the supernova remnant CTA 1
• Deep optical study of the mixed-morphology supernova remnant G 132.7+1.3 (HB3)
• An analysis of the possible thermal emission at radio frequencies from an evolved supernova remnant HB 3 (G132.7 + 1.3): revisited
• Radio polarization observations of large supernova remnants at 6cm