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Non-Zeeman Circular Polarization of 12 CO in SNR IC 443

Non-Zeeman Circular Polarization of 12 CO in SNR IC 443. Talayeh Hezareh ( Max-Planck-Institut für Radioastronomie ). o r… How I Caught M y D ata Lying to Me . H . Wiesemeyer ( MPIfR , DE ) M. Houde ( Western University, CA ) A. Gusdorf ( ENS, FR ) G. Siringo ( ESO, CL )

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Non-Zeeman Circular Polarization of 12 CO in SNR IC 443

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  1. Non-Zeeman Circular Polarization of 12CO in SNR IC 443 Talayeh Hezareh (Max-Planck-Institut für Radioastronomie) or… How I Caught My Data Lying to Me H. Wiesemeyer (MPIfR, DE) M. Houde (Western University, CA) A. Gusdorf (ENS, FR) G. Siringo (ESO, CL) C. Thum (IRAM, ES) MPIA, Heidelberg 21-05-13 Hezareh et al. 2013, A&A, submitted

  2. Tracing magnetic fields in (sub-)mm regime • Polarization in thermal emission of dust: B-field mapped in plane of sky: Bpos • Polarization in spectral lines of gas molecules: Zeeman effect : Blos Goldreich-Kylafis effect : Bpos • Ion-neutral spectral line-width comparison method: Li & Houde technique : Bpos MPIA, Heidelberg 21-05-13

  3. The Goldreich-Kylafis effect Alignment of molecules with magnetic field with Anisotropic optical depths and/or Anisotropic radiation field then Imbalance in 'π' and 'σ' populations so Linear polarization | or || to magnetic field _ (Goldreich& Kylafis1981) (Cortes, Crutcher, & Watson 2005) MPIA, Heidelberg 21-05-13

  4. Initial aimofthiswork • Nosuccessfulpriordetectionwith XPOL at IRAM 30-m • Detectthe Goldreich-Kylafiseffect in CO spectrallines in a regionsupposedlystrongerthandust • A regionwith a clearsourceofanisotropy, eithervelocitygradientsorradiationw.r.t. the B-field • A goodcandidate: SNR IC 443 MPIA, Heidelberg 21-05-13

  5. SNR IC 443 IC443-NE IC443-G IC443-B IC443-C LABOCA map @ 345 GHz (A. Gusdorf) MPIA, Heidelberg 21-05-13

  6. The Stokes parameters We mapped IC 443-G in CO (2-1) and (1-0) simultaneously at IRAM 30-m Obtained the 4 Stokes parameters with the correlatorpolarimeter XPOL: MPIA, Heidelberg 21-05-13

  7. CO(2-1) in IC 443-G Dec offset (arcsec) RA offset (arcsec) MPIA, Heidelberg 21-05-13

  8. Stokes maps of Mercury (1mm) Stokes Q Stokes I Instrumental Q = IIC443G * QMercury Instrumental U = IIC443G * UMercury Instrumental V = IIC443G * VMercury Stokes U Stokes V Instrumental Q, U, V at (0,0): 0.09-0.11%, side-lobes up to 3% polarized MPIA, Heidelberg 21-05-13

  9. CO polarizationmaps after IP correction CO(2-1) CO(1-0) MPIA, Heidelberg 21-05-13

  10. Dustpolarizationmap (PolKa) CO(1-0) Dust MPIA, Heidelberg 21-05-13

  11. Circularpolarizationof CO in Orion KL Observations performed with FSPPol at the CSO Circular polarization observed at same position where linear polarization was previously observed (Girart et al. 2004) (Hezareh & Houde 2010) (Houde, Hezareh et al. 2013) MPIA, Heidelberg 21-05-13

  12. Circularpolarizationof CO in IC 443-G circular polarization linear polarization MPIA, Heidelberg 21-05-13

  13. Not a detection of the Zeeman Effect Crutcheret al. 1999 OMC1n CN (N =1 0) at 113 GHz Zeeman splitting 2 HzμG-1 while CO (J =1 0) at 115 GHz Zeeman splitting 0.2 mHzμG-1 MPIA, Heidelberg 21-05-13

  14. Stokes V maps of CO CO(2-1) CO(1-0) MPIA, Heidelberg 21-05-13

  15. Linear tocircularpolarizationconversion - anisotropicresonant scattering Incident background radiation Scattered radiation Stokes parameters in the frame of foreground magnetic field Increase of ϕ decrease of u increase of v indifference of q (Houde, Hezareh et al. 2013) MPIA, Heidelberg 21-05-13

  16. Anisotropic resonant scattering relative phase shift : the Zeeman splitting : inclination angle of the magnetic field : the frequency of scattered photon : frequency of transition : density of CO molecules in lower state : the size of interaction region : the spontaneous emission coefficient (~ 10-6 s-1) : the incident (scattered) linear polarization energy density : resonant scattering integral over incident linear polarization profile MPIA, Heidelberg 21-05-13

  17. Polarization conversion experiment Convert Stokes V into U in the frame of foreground B-field: Make new maps with: MPIA, Heidelberg 21-05-13

  18. Difference in theanglesofdustand CO(2-1) polarizationvectors grey: before correction red: after correction MPIA, Heidelberg 21-05-13

  19. PolarizationcorrectionforCO(2-1) before after MPIA, Heidelberg 21-05-13

  20. Difference in theanglesofdustand CO(1-0) polarizationvectors grey: before correction red: after correction MPIA, Heidelberg 21-05-13

  21. PolarizationcorrectionforCO(1-0) MPIA, Heidelberg 21-05-13

  22. Upcoming Work • Calculate the magnetic field strength and ratio of turbulent to ordered components from the dispersion of the polarization angles in CO and dust maps (Hildebrand et al 2009; Houde et al. 2009) • Verify that the polarization transformation is indeed due to anisotropic resonant scattering • Quantify the field strength as a function of the phase difference in the scattered amplitudes: a chance to measure B-field using tracers without Zeeman sensitivity (Houde et al 2013) • Apply this analysis to other SF regions and SNRs (W44) MPIA, Heidelberg 21-05-13

  23. Thank you! MPIA, Heidelberg 21-05-13

  24. Phase shift distribution for CO(1-0) Label the figures MPIA, Heidelberg 21-05-13

  25. Phase shift distribution for CO(2-1) MPIA, Heidelberg 21-05-13

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