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Primary results of polarization survey of large-SNRs at 6 cm Li Xiao, Xiao. Hui Sun, Chen Wang, Wei. Bin Shi, Wolfgang Reich, Jin. Lin Han Partner Group of MPIf. R at NAOC
outlines • • • System parameter of Urumqi 25 m telescope How we choose the observation target? The large-SNRs observation list preliminary results The future work
System parameters/Calibrators • • Central frequency: 4800 MHz 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 m. K for 1 s integration time • Primary Calibrator: 3 C 286 – Intensity: 7. 5 Jy, – Polarization Angle: 33 deg, – Polarization Percent: 11. 3%
How we choose the observation target? • Urumqi 25 m telescope observation condition: DEC>-30 deg • 111 SNRs at dec >-30 deg (D. A. Green cataloge) • Object scale : X>80’ or X+Y>120’, • Our target is 19 large-SNRs (15 already observed)
the large-SNRs observation list Name • • • • • G 28. 8+1. 5 G 39. 7 -2. 0(W 50, SS 433) G 65. 1+0. 6 G 69. 0+2. 7(CTB 80) G 74. 0 -8. 5(Cygnus loop) G 82. 2+5. 3(W 63) G 89. 0+4. 7(HB 21) 120*90 G 93. 7 -0. 2(CTB 104 A, DA 551) G 114. 3+0. 3 G 116. 5+1. 1 G 119. 5+10. 2(CTA 1) G 126. 2+1. 6 & G 127. 1+0. 5 G 132. 7+1. 3(HB 3) G 156. 2+5. 7 G 160. 9+2. 6(HB 9) G 166. 2+2. 5 OA 184 G 180 -1. 7(S 147) G 205. 5+0. 5 Size 100 120*60 90*50 80 230*160 95*65 3*3 80 90*55 80*60 90 70 80 110 140*120 90*70 180 220 Scan size obs. times 3*3 3*3 4. 2*4. 8 4. 2*4. 2 0 0 1 2 5 4 6 3*3 3*3 4*4 5*5 5*5 6 4 4 7 4 4 8 6 4 2 0
Preliminary result 10 good maps reduced in all • • • W 63 HB 21 HB 9 G 156. 2+5. 7 G 114. 3+0. 3 G 116. 5+1. 1 • CTB 104 A (G 93. 7+0. 2) • Cygnus loop(G 74. 0 -8. 5) • G 126. 2+1. 6 & G 127. 1+0. 5 • CTA 1 (G 119. 5+10. 2)
W 63 (G 82. 5+5. 3) Size: 95’X 65’; Type: S; Dist: 1. 3~1. 9 kpc • Previous Observations: – Radio: the remnant locates in the Cygnus X complex. It displays a non -circular , elliptical shape in radio map – Optical: in complex region, but spectra indicate SNR filaments – X-rays: Einstein and ROSAT detected • Our Observation – 3 coverages – Flux density: 46 +/- 5 Jy – First complete map at highest frequency up to data
ROSAT image (soft X-ray) + radio contours(326 Mhz) 326 Mhz 5 Ghz (Angerhofer et al. 1977) (Rengelink et al. 1997) Effelsberg 100 m 2. 7 Mhz (Reich et al. 2003)
HB 21 (G 89. 0+4. 7) Size: 120’ X 90’; Type: S; Distance: 0. 8 kpc; • Previous observation: – Radio: distorted shell; 4 C 50. 52, an extragalactic double within the – boundary of the remnants Optical: filaments possibly associated – X-rays: Centrally brightended • Our observation: – – – 4 coverages Flux density: 114 +/- 11 Jy First Total Intensity and Polarization observation at highest frequency up to data
408 Mhz (Tatematsu et al. 1990) ROSAT image (leahy et al. 1996) 11 cm (haslam et al. 1975) 35 cm (Reich et al. 2003)
HB 9 (G 160. 9+2. 6) Size: 140’X 120’; Type: S; Dist: 4 kpc • Previous Observations: – Radio: large, filamentary shell; Pulsar within boundary of the remnant, plus several nearby compact sources – Optical: incomplete shell – X-rays: Centrally brightened • Our Observation – 4 coverages – Flux density: 35 +/- 4 Jy – First Polarization observation at highest frequency up to data
4. 7 Ghz (leahy et al. 1998) 863 Mhz (Reich et al. 2003) 151 Mhz (leahy et al. 1998) ROSAT image (leahy et al. 1995)
CTB 104 A (G 93. 7+0. 2) Size: 80’; Type: S; Dist: 1. 5 kpc • Previous Observations: – Radio: faint shell, distorted with many protrusions, radio source in north is SNR 3 C 434. 1, in south is HII region – X-rays: no detected • Our Observation: – 3 coverages – Flux density: 26 +/- 3 Jy; – The sensitivity 10 times larger than the previous observation at 4. 75 Ghz
4. 75 Ghz (Mantovani et al. 1991) 2. 7 Ghz (Velusamy & Kundu 1974) 1. 7 Ghz (Mantovani et al. 1982) 408 Mhz 1. 4 Ghz
G 114. 3+0. 3 Size: 90’X 55’; Type: S; Dist: 3. 0~3. 8 kpc • Previous Observations: – Radio: shell, with HII region S 165 within the boundary of the remnant. Plusar 2334+61 near centre of remnant. – Optical: faint emission in centre and to S. – X-rays: no detected • Our Observation: – 3 coverages – flux density: 7. 9 +/- 1 Jy – First Polarization observation at highest frequency up to data
4. 7 Ghz (condon et al. 1994) 1. 4 Ghz (Uraniker et al. 2004) 2. 7 Ghz (Reich et al. 1981)
G 116. 5+1. 1 Size: 80’X 60’; Type: S; Dist: 3. 6~5. 2 kpc & CTB 1 Size: 34’; Type: S; Dist: 2. 7 kpc • Previous Observations: – Radio: G 116. 5+1. 1 distinct shell, with high polarization. CTB 1 incomplete shell, with pulsar to NE – X-rays: ROSAT detected for CTB 1 • Our Observations: – 4 coverages – Flux density: G 116. 5+1. 1: 7. 4 +/- 1 Jy CTB 1: 5. 2 +/- 1 Jy – First Total Intensity and Polarization observation at highest frequency up to data for G 116. 5+1. 1
2. 7 Ghz (Reich et al. 1981) 1. 4 Ghz (Uraniker et al. 2004) CTB 1 4. 8 Ghz of CTB 1 (Angerhofer et al. 1977) ROSAT image of CTB 1 (Craig et al. 1997)
G 126. 2+1. 6 Size: 70’; Type: S? ; Spectral Index: varies & G 127. 1+0. 5 Size: 45’; Type: S; Dist: 1. 2 -1. 3 kpc • Previous Observations: – Radio: G 126. 2+1. 6 poorly defined shell; with weak polarization G 127. 1+0. 5 distinct shell, bright central source be extragalactic active galaxy. – Optical: detected • Our Observation: – 4 coverages – Flux density: G 126. 2+1. 6: 4 +/- 1 Jy; G 127. 1+0. 5: 10 +/- 1 Jy – First polarization observation for G 126. 2+1. 6 up to data
2. 7 Ghz (furst et al. 1983) 4. 8 Ghz (furst et al. 1984) G 127. 1+0. 5 408 Mhz (Joncas et al. 1989) 863 Mhz 1. 4 Ghz
CTA 1 (G 119. 5+10. 2) Size: 90’; Type: S; Dist: 3. 6~5. 2 kpc • Previous Observations: – Radio: incomplete shell; typical structure of breakout; compact, central X/gamma-ray source. – Optical: faint diffuse nebulosities. – X-rays: centrally brightened • Our Observation: – 6 coverages – Flux density: 12 +/- 1 Jy – First Total Intensity and Polarization observation at the highest frequency up to data
2. 7 Ghz (Sieber et al. 1981) 151 Mhz (Sieber et al. 1981) 1. 4 Ghz (image) + ROSAT (contours)
G 156. 2+5. 7 Size: 110’; Type: S; Spectral Index: 0. 5 • Previous Observations: – Radio: faint shell – X-Ray: central brightened • Our Observation: – 5 coverages – Flux density: 4 +/- 1 Jy – One of the most weak SNR observed
1. 4 Ghz (Reich et al. 1992) 2. 7 Ghz (Reich et al. 1992) ROSAT image (Pfeffermann et al. 1991)
Cygnus loop (G 74. 0 -8. 5) • 5 coverages; • r. m. s: 1. 0 m. K in I, 0. 4 m. K in PI; • Flux density: 90 +/- 9 Jy Spectral index: 0. 40 • polarization percentage: <= 35% • confirm the variable character of CL 4 with timescale of ~30 days • distorted magnetic field in the northern part indicating strong interaction between blast wave and cloud • the polarization image support the two-SNR scenario
The future work l l l by combing the maps at other radio bands – make the spectral index maps – calculate the RM maps – polarization and depolarization analysis by combing X-ray observation altogether by statisticing the physics properties of SNRs Better understand the physical process constrain theoretical models
Thank you!
CTB 104 A (G 93. 7+0. 2) • coherent polarized structure extends outside SNR to the northwest
G 126. 2+1. 6 & G 127. 1+0. 5 • a new SNR candidate in the east?
