A Sino-German λ6 cm polarization survey of the Galactic plane

V. Large supernova remnants

¹ National Astronomical Observatories, CAS, Jia-20 Datun Road, Chaoyang District, 100012 Beijing, PR China
e-mail: bearwards@gmail.com (XYG); hjl@nao.cas.cn (HJL)
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Received: 14 December 2010
Accepted: 22 February 2011

Abstract

Context. Observations of large supernova remnants (SNRs) at high frequencies are rare, but provide valuable information about their physical properties.

Aims. The total intensity and polarization properties of 16 large SNRs in the Galactic plane are investigated based on observations of the Urumqi λ6 cm polarization survey of the Galactic plane with an angular resolution of 95.

Methods. We extracted total intensity and linear polarization maps of large SNRs from the Urumqi λ6 cm survey, obtained their integrated flux densities, and derived the radio spectra by using these flux densities together with previously published flux densities at various frequencies. In particular, Effelsberg λ11 cm and λ21 cm survey data were used to calculate integrated flux densities. The λ6 cm polarization data also delineate the magnetic field structures of the SNRs.

Results. We present the first total intensity maps at λ6 cm for SNRs G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5 (Monoceros Nebula), and G206.9+2.3 (PKS 0646+06) and the first polarization measurements at λ6 cm for SNRs G82.2+5.3 (W63), G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5 (Monoceros Nebula), and G206.9+2.3 (PKS 0646+06). Most of the newly derived integrated radio spectra are consistent with previous results. The new flux densities obtained from the Urumqi λ6 cm, Effelsberg λ11 cm and λ21 cm surveys are crucial to determine the spectra of SNR G65.1+0.6, G69.0+2.7 (CTB 80), G93.7−0.2, and G114.3+0.3. We find that G192.8−1.1 (PKS 0607+17) consists of background sources, H ii regions, and extended diffuse emission of thermal nature, and conclude that G192.8−1.1 is not a SNR.