Primary results of polarization survey of large-SNRs at 6cm

Li Xiao, XiaoHui Sun, Chen Wang,

WeiBin Shi, Wolfgang Reich, JinLin Han

Partner Group of MPIfR at NAOC

outlines

• System parameter of Urumqi 25m 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 mK for 1s integration time

• Primary Calibrator: 3C286– Intensity: 7.5 Jy, – Polarization Angle: 33 deg, – Polarization Percent: 11.3%

How we choose the observation target?

• Urumqi 25m 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 listName Size Scan size obs.times • G28.8+1.5 100 3*3 0• G39.7-2.0(W50, SS433) 120*60 3*3 0• G65.1+0.6 90*50 3*3 1• G69.0+2.7(CTB80) 80 3*3 2• G74.0-8.5(Cygnus loop) 230*160 4.2*4.8 5• G82.2+5.3(W63) 95*65 4.2*4.2 4• G89.0+4.7(HB21) 120*90 3*3 6• G93.7-0.2(CTB104A, DA551) 80 3*3 6• G114.3+0.3 90*55 3*3 4• G116.5+1.1 80*60 3*3 4• G119.5+10.2(CTA1) 90 3*3 7• G126.2+1.6 & G127.1+0.5 70 4*4 4• G132.7+1.3(HB3) 80 5*5 4• G156.2+5.7 110 3*3 8• G160.9+2.6(HB9) 140*120 4*4 6• G166.2+2.5OA184 90*70 5*5 4• G180-1.7(S147) 180 5*5 2• G205.5+0.5 220 5*5 0

Preliminary result

• W63• HB21• HB9• G156.2+5.7• G114.3+0.3• G116.5+1.1

10 good maps reduced in all

•CTB104A (G93.7+0.2)•Cygnus loop(G74.0-8.5)•G126.2+1.6 & G127.1+0.5•CTA1 (G119.5+10.2)

• Previous Observations:– Radio: the remnant locates in the Cygnus X complex. It displays a no

n-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

W63 (G82.5+5.3) Size: 95’X65’; Type:S; Dist:1.3~1.9 kpc

ROSAT image (soft X-ray) + radio contours(326Mhz)

5Ghz(Angerhofer et al. 1977)

Effelsberg 100m 2.7Mhz(Reich et al. 2003)

326Mhz(Rengelink et al. 1997)

• Previous observation:– Radio: distorted shell; 4C50.52, 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

HB21 (G89.0+4.7) Size: 120’ X 90’; Type: S; Distance: 0.8 kpc;

ROSAT image

(leahy et al. 1996)11cm

(haslam et al. 1975)35cm

(Reich et al. 2003)

408Mhz(Tatematsu et al. 1990)

• Previous Observations:– Radio: large, filamentary shell; Pulsar within boundary of the remnan

t, 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

HB9 (G160.9+2.6) Size: 140’X120’; Type: S; Dist: 4kpc

4.7Ghz(leahy et al. 1998)

863Mhz(Reich et al. 2003) 151Mhz

(leahy et al. 1998)

ROSAT image(leahy et al. 1995)

• Previous Observations:– Radio: faint shell, distorted with many protrusions, radio source in no

rth is SNR 3C434.1, 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 4.75Ghz

CTB104A (G93.7+0.2) Size: 80’; Type: S; Dist: 1.5kpc

2.7Ghz(Velusamy & Kundu 1974)

1.7Ghz(Mantovani et al. 1982)

4.75Ghz(Mantovani et al. 1991)

1.4Ghz408Mhz

• Previous Observations:– Radio: shell, with HII region S165 within the boundary of the remnan

t. 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

G114.3+0.3 Size: 90’X55’; Type: S; Dist: 3.0~3.8kpc

2.7Ghz(Reich et al. 1981)

4.7Ghz(condon et al. 1994)

1.4Ghz(Uraniker et al. 2004)

• Previous Observations:– Radio: G116.5+1.1 distinct shell, with high polarization. CTB1 incompl

ete shell, with pulsar to NE

– X-rays: ROSAT detected for CTB1

• Our Observations:– 4 coverages– Flux density:G116.5+1.1: 7.4 +/- 1 Jy CTB1: 5.2 +/- 1 Jy

– First Total Intensity and Polarization observation at highest frequency up to data for G116.5+1.1

G116.5+1.1 Size: 80’X60’; Type: S; Dist: 3.6~5.2kpc& CTB1 Size: 34’; Type: S; Dist: 2.7kpc

2.7Ghz(Reich et al. 1981)

1.4Ghz(Uraniker et al. 2004)

ROSAT image of CTB1(Craig et al. 1997)

4.8Ghz of CTB1(Angerhofer et al. 1977)

CTB1

• Previous Observations:– Radio: G126.2+1.6 poorly defined shell; with weak polarization

G127.1+0.5 distinct shell, bright central source be extragalactic active galaxy.

– Optical: detected

• Our Observation:– 4 coverages– Flux density: G126.2+1.6: 4 +/- 1Jy; G127.1+0.5: 10 +/- 1Jy

– First polarization observation for G126.2+1.6 up to data

G126.2+1.6 Size: 70’; Type: S?; Spectral Index: varies

& G127.1+0.5 Size: 45’; Type: S; Dist: 1.2-1.3kpc

408Mhz

(Joncas et al. 1989) 863Mhz 1.4Ghz

2.7Ghz(furst et al. 1983)

4.8Ghz(furst et al. 1984)

G127.1+0.5

• Previous Observations:– Radio: incomplete shell; typical structure of breakout; compact, centr

al 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

CTA1 (G119.5+10.2) Size: 90’; Type: S; Dist: 3.6~5.2kpc

1.4Ghz (image) + ROSAT (contours)

1.7Ghz(Sieber et al. 1981)

2.7Ghz(Sieber et al. 1981)

151Mhz(Sieber et al. 1981)

G156.2+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

1.4Ghz(Reich et al. 1992)

2.7Ghz(Reich et al. 1992) ROSAT image

(Pfeffermann et al. 1991)

• 5 coverages;

• r.m.s: 1.0 mK in I, 0.4 mK in PI;

• Flux density: 90 +/- 9 Jy Spectral index: 0.40

• polarization percentage: <= 35%

Cygnus loop (G74.0-8.5)

• confirm the variable character of CL 4 with timescale of ~30days

• 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

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 the theoretical models

Thank you!

CTB104A (G93.7+0.2)

• coherent polarized structure extends outside SNR to the northwest

• a new SNR candidate in the east?

G126.2+1.6 & G127.1+0.5