Observations of SNR G156.2+5.7 at 6cm

JianWen Xu, Li Xiao, XiaoHui Sun, Chen Wang,

Wolfgang Reich, JinLin Han

Partner Group of MPIfR at NAOC

System parameters/Calibrators• Central frequency: 4.8 GHz• Bandwidth: 600 MHz• System temperature: 22-25 K• HPBW: 9.5 arcmin• Aperture efficiency: 62%• Beam efficiency: 67%• Conversion factor: 0.164 K/Jy• r.m.s: 1.5 mK for 1s integration tim• Primary Calibrator: 3C138

– Intensity: 3.64 Jy, – Polarization Angle: 169 deg, – Polarization Percent: 11.7%

Properties of SNR G156.2+5.7

• Identified firstly by the ROSAT observatory in the all-sky survey for X-ray sources

• Among the 10 brightest X-ray Galactic SNRs

• The lowest radio surface brightness among all known SNRs

• Common magnetic field strength & therefore a low electron density

Some Parameters of SNR G156.2+5.7

• Spectral index = 0.50.15 (Reich et al. 1992)

• A distance of d 3kpc (Pfeffermann et al. 1991)

• A diameter of 108’, or 95pc (Pfeffermann et al. 1991)

• Type I progenitor SN of E0 = 1051erg (Reich et al. 1992)

• An age of 2.6104yr (Pfeffermann et al. 1991)

• r.m.s: 1.0 mK in I

• Flux density:2.2+/-0.6Jy

• polarization percentage :

Left:<= 40%,

Right:<=70%

G156.2+5.7

• one of the most weak SNRs • The red source in the southwest with strongest radio emission is probably an extragalactic one

Total intensity (image)

• r.m.s: 1.0 mK in I

• Flux density:2.2+/-0.6Jy

• polarization percentage :

Left:<= 40%,

Right:<=70%

G156.2+5.7

Total intensity (image+contours)

• one of the most weak SNRs • The red source in the southwest with strongest radio emission is probably an extragalactic one

• r.m.s: 1.0 mK in I

• Flux density:2.2+/-0.6Jy

• polarization percentage :

Left:<= 40%,

Right:<=70%

G156.2+5.7

Intensity (image) + B (bars) + Polarization Intensity (contours)

• one of the most weak SNRs • small patchy of polarization in the center

---probably local structure

• r.m.s: 0.25 K TB in I

• Flux density:4.2+/-1.0Jy

• polarization percentage :

unavailable

G156.2+5.7

Intensity (image+contours) (Reich et al. 1992)

• one of the most weak SNRs • The source in the southwest with strongest radio emission is probably an extragalactic one

• r.m.s: unavailable

• Flux density:3.0+/-1.0Jy

• polarization percentage :

Left:<= 75%,

Right:<=50%

G156.2+5.7

Intensity (image) + B (bars) + Polarization Intensity (contours)(Reich et al. 1992)

• one of the most weak SNRs • small patchy of polarization in the center ---probably local structure

• r.m.s: 0.5 mK in PI

• Flux density:2.2+/-0.6Jy

• Polarization percentage :

Left:<= 40%,

Right:<=70%

G156.2+5.7

Polarization Intensity (contours)

• one of the most weak SNRs

• small patchy of polarization in the center ---probably local structure

• r.m.s: 0.5 mK in PI

• Flux density:2.2+/-0.6Jy

• polarization percentage :

Left:<= 40%,

Right:<=70%

G156.2+5.7

Polarization Intensity (contours) + B (bars)

• one of the most weak SNRs • small patchy of polarization in the center ---probably local structure

• r.m.s: unavailable

• Flux density:3.0+/-1.0Jy

• polarization percentage :

Left:<= 75%,

Right:<=50%

G156.2+5.7

Polarization Intensity (contours) + B (bars) (Reich et al. 1992)

• one of the most weak SNRs • small patchy of polarization in the center ---probably local structure

• r.m.s: 1.0 mK in I, 0.5 mK in PI• Flux density:2.2+/-0.6Jy• polarization percentage : Left:<

= 40%, Right:<=70%

G156.2+5.7

Polarization Percentage (contours)

• one of the most weak SNRs • small patchy of polarization in the center ---probably local structure

Integrated flux densities

--by open circle

(derived from our observations)

--by filled circle

(taken from Reich et al. 1992)

G156.2+5.7

Radio spectrum at 4.8 GHz

Spectral index

= 0.540.06

Summary

• Total flux density is 2.2 0.6 Jy at 4.8GHz

• Spectral index is = 0.540.06

• Surface brightness = 2.910-22 W m-2 Hz-1 sr-1

at 4.8GHz

Thank You