Multi-Frequency Polarization Structure in 3C273 Jet

"Study the multi-frequency polarization structure of the sub-pc scale jet in 3C273 at mm-wavelengths. Explore VLBI-scale Faraday rotation and EVPA differences. Analyze 43-86 GHz EVPA variations and depolarization patterns in the core region. Understand the polarimetry of 3C273 using VLBA data. Investigate differences in EVPA between 86 and 43 GHz and the polarization degree. Gain insights into the complexities of polarization properties in the jet of 3C273 at different frequencies."

• Astronomy
• VLBI
• Faraday Rotation
• Polarization
• 3C273

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1. Multi-frequency polarization structure of the (sub-)pc scale jet in 3C273 at mm-wavelengths Tuomas Savolainen Aalto University Mets hovi Radio Observatory, Finland Max-Planck-Institut f r Radioastronomie, Germany

2. VLBI-scale Faraday rotation in the jet of 3C273 at cm-wavelengths McKinney & Blandford 2009 Zavala & Taylor (2005) Hovatta et al. (2012) 100 ?? Asada et al. (2002) 2

3. 43-86 GHz EVPA difference (Attridge et al. 2005) McKinney & Blandford 2009 No absolute EVPA calibration at 86 GHz, but 67 change in ?43 86 across the jet at 0.8mas from the core RM > 3.2 104rad m 2 Depolarized core. If external, ???> 5 104rad/m2 100 ?? 3

4. 43-86 GHz EVPA difference (Hada et al. 2016) McKinney & Blandford 2009 100 ?? No absolute EVPA calibration at 86 GHz. ? = 50 indicates RM > 2.4 104rad m 2 4

5. 15-86 GHz VLBA polarimetry of 3C273 in Oct 2010 McKinney & Blandford 2009 24 GHz 15 GHz 100 ?? ??????????= 2500 ??????????= 1300 5

6. 15-86 GHz VLBA polarimetry of 3C273 in Oct 2010 McKinney & Blandford 2009 86 GHz 43 GHz 100 ?? 86 GHz EVPA calibration using IRAM 30-m (Agudo et al. 2014) ??????????= 260 ??????????= 600 6

7. Differences in EVPA between 86 and 43 GHz McKinney & Blandford 2009 100 ?? 7

8. Differences in EVPA between 86 and 43 GHz ?? ? ?????? ? ? McKinney & Blandford 2009 ? = +? ? = ?? ?? ~ ? ?????? ? ? 100 ?? ? = ?? 8

9. Polarization degree and depolarization McKinney & Blandford 2009 m ?.?% m = ? ?% m = ?? ?% m = ? ?% 100 ?? m ??% 43 GHz 86 GHz Depolarization close to the core. If due to external Faraday dispersion , ??? 2 104rad/m2 9

10. Need for higher N-S resolution Super-resolved 0.15 mas circ. beam Transverse polarization structure within first milliarcsec (2.4 pc / 4000 ??) Thread of polarized emission with EVPA following the bend inside the jet? Need for more N-S resolution and more sensitivity at 86GHz: GMVA+ALMA observations last April (Akiyama et al.) 10

11. Summary Obtained high-quality 15-86 GHz polarimetric VLBA images of 3C273 including EVPA calibration also at 86 GHz Confirms the earlier results of RM 2 104rad m 2inside the first milliarcsecond Depolarized core at 43 GHz indicating ??? 2 104rad/m2 Calibrated 86 GHz EVPAs seem to align with a bend inside the first milliarcsecond 11

12. BACKUP SLIDES 12

13. RM mapping at 86-24 GHz McKinney & Blandford 2009 100 ?? Problems: (very) poor ?2-coverage, not enough resolution at 24 GHz, possible non- ?2 behaviour 13

14. Multifrequency VLBA polarimetry at 15-86 GHz Observations on 27 Oct 2010 (part of a longer monitoring program) Obs. freqs. 15, 24, 43 and 86 GHz Targets: 3C273, 3C279 Additional calibrators: 0923+392, 1308+326 D-term rms: 0.024 (86GHz), 0.010 (43GHz), 0.006 (24GHz), 0.004 (15GHz) Absolute EVPA calibration by UMRAO (15GHz, M.Aller), VLA (24, 43 GHz), IRAM-30 (86 GHz; Agudo et al. 2014) ?(EVPA): 5 (15GHz), 5 (24GHz), 5 (43GHz), 7 (86GHz) 14

15. 43-86 GHz spectral index image McKinney & Blandford 2009 100 ?? 15

16. Differences in EVPA between 86 and 43 GHz ?? ? ?????? ? ? McKinney & Blandford 2009 ? = +? ? = ?? ?? ~ ? ?????? ? ? 100 ?? ? = ?? 16

17. Polarization degree along the jet McKinney & Blandford 2009 43 GHz 86 GHz 100 ?? 17

18. Blank slide McKinney & Blandford 2009 100 ?? 18