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UNNOFIT inversion

THEMIS. UNNOFIT inversion. V. Bommier, J. Rayrole, M. Mart ínez González , G. Molodij Paris-Meudon Observatory (France). Atelier "Inversion et transfert multidimensionnel", Beaulieu sur mer, France, 8-10 Octobre 2007. UNNOFIT INVERSION. presentation of UNNOFIT, accuracy

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UNNOFIT inversion

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  1. THEMIS UNNOFIT inversion V. Bommier, J. Rayrole, M. Martínez González,G. Molodij Paris-Meudon Observatory (France) Atelier "Inversion et transfert multidimensionnel", Beaulieu sur mer, France, 8-10 Octobre 2007

  2. UNNOFIT INVERSION • presentation of UNNOFIT, accuracy • Comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters • Initialisation of UNNOFIT with PCA results • Comparison UNNOFIT / SIR results (M. Martínez González)  Introduction of a velocity gradient (J. Rayrole, G. Molodij)

  3. typical INTRANETWORK low polarized pixel UNNOFIT Landolfi, M., Landi Degl'Innocenti, E., Arena, P., 1984, Solar Physics 93, 269 • Unno-Rachkowsky analytical solution in a Milne-Eddington atmosphere • Marquardt algorithm to reach the minimum 2 (Harvey et al., 1972, Auer et al., 1977) •  Magneto-optical and damping effects (Landolfi & Landi Degl'Innocenti, 1982)

  4. • Present work: introduction of a 9th fitted parameter: the magnetic filling factor •  Skumanich & Lites (1987): Inm constant (average of the observation) • our work: same physical conditions (except the magnetic field) for Inm and Im Inm varies throughout the map (umbra, penumbra, plages, faculæ, quiet, etc...) UNNOFIT • 8 fitted parameters: 1 – the line strength 0 2 – the Zeeman splitting H 3 – the Doppler width D 4 – the damping parameter of the Voigt function  5 – one single parameter b describing the Milne-Eddington atmosphere 6 – the line central wavelength 7 & 8 – the field inclination and azimuth angles

  5. minimum of  per pixel for two varying parameters: – the magnetic field intensity – the magnetic filling factor full scale: the polarimetric sensitivity UNNOFIT

  6. minimum of  per pixel for two varying parameters: – the magnetic field inclination – the magnetic field azimuth full scale: the polarimetric sensitivity UNNOFIT

  7. noise level measurement by wavelet filtering technique and determination of the standard deviation

  8. 1 line (in the visible range)  Determination of the local average magnetic field strength test: comparison known input vs inverted output: the filling factor  and the field strength B are not separately recovered, but their product B, the local average magnetic field strength, is recovered.

  9. histograms of the differences inverted-initial (UNNOFIT accuracy) (input) B >= 45G NETWORK (input) B < 45G INTER- NETWORK

  10. comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 9 parameters (with filling factor) Blim= 20 Gauss UNNOFIT 8 parameters (no filling factor) Blim= 100 Gauss

  11. Accuracy

  12. no filling factor ( = 1) with filling factor (  1) Orders of magnitude

  13. comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 9 parameters (with filling factor) UNNOFIT 8 parameters (no filling factor)

  14. comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 9 parameters (with filling factor) UNNOFIT 8 parameters (no filling factor)

  15. Symmetrisation of the profiles beam exchange: recenter (spectrally) the I+X and I–X profiles obtained in the same channel at different times (for Q and U) the idea is that the l.o.s. velocity has changed between the two times the result is symmetrised profiles

  16. comparison unsymmetrised / symmetrised symmetrised (with recentering before subtraction) unsymmetrised (no recentering before subtraction) QUIET SUN 25 July 2007 TIP-TILT ON pixel size 0.2 arcsec

  17. INITIALISATION OF UNNOFIT WITH PCA RESULTS data: active region, 6 November 2004 provided by BASS2000 (codes runned by BASS2000): – polarimetric analysis results SQUV code A. Sainz  Stokes profiles (submitted to UNNOFIT inversion) – PCA analysis results A. Lopez's code  magnetic field vector and filling factor

  18. INITIALISATION OF UNNOFIT WITH PCA RESULTS initialisation (and acceleration) of UNNOFIT: 2 proposed methods – initialisation with PCA analysis results ("PCA initialisation") – initialisation with results of neighbour pixels ("neighbour initialisation)

  19. INITIALISATION OF UNNOFIT WITH PCA RESULTS difference with the "normal" (i.e., non accelerated) solution PCA initialisation neighbour initialisation

  20. INITIALISATION OF UNNOFIT WITH PCA RESULTS proportion of "bad" pixels where the magnetic field vector differs with: – more than 25% in field strength – or more than 20 degrees in inclination or azimuth angle with respect to the "normal" (i.e., non accelerated) solution: PCA initialisation 22.0% of "bad" pixels neighbour initialisation 1.2% of "bad" pixels

  21. COMPARISON UNNOFIT/PCA data: active region, 6 November 2004, provided by BASS2000 (codes runned by BASS2000): – polarimetric analysis results: SQUV code A. Sainz  Stokes profiles (submitted to UNNOFIT inversion) – PCA analysis results: A. Lopez's code  magnetic field vector and filling factor PCA UNNOFIT

  22. COMPARISON UNNOFIT/PCA inclination angle angle with the horizontal plane PCA UNNOFIT

  23. COMPARISON UNNOFIT/PCA data: active region, 6 November 2004, provided by BASS2000 (codes runned by BASS2000): – polarimetric analysis results: SQUV code A. Sainz  Stokes profiles (submitted to UNNOFIT inversion) – PCA analysis results: A. Lopez's code  magnetic field vector and filling factor

  24. COMPARISON UNNOFIT/SIR As UNNOFIT provides only the product B, SIR was runned with: – one signe line Fe I 6302.5 Å – one single magnetic component (homogeneous field) – 11 free parameters: – the temperature (5 nodes) – the microturbulent velocity – the macroturbulent velocity – the line-of-sight velocity – the magnetic field strength – the magnetic field inclination and azimuth angles

  25. UNNOFIT/SIR Comparison : Sunspot field strength differences in inclination azimuth

  26. UNNOFIT/SIR Comparison : Quiet Sun field strength differences in inclination azimuth

  27. Validity of the Milne-Eddington Approximation linear logarithmic Linearity of the source function at   1 NLTE computation of the source function in a VALC atmosphere Fe I 6302.5 Å opacity

  28. concerns the line bisector  theory: the 2 line bisectors of I+V and I-V are symmetrical I-V I+V  observation by J. Rayrole: the 2 line bisectors of I+V and I-V are not symmetrical but are RECTILINEAR (in ) I-V I+V  VELOCITY GRADIENT Observation by J. RAYROLE

  29. VELOCITY GRADIENT Empirical law by J. RAYROLE and G. MOLODIJ absorption coefficient (that enters the Unno-Rachkowsky solution): • modification of UNNOFIT to determine a 10th parameter, V V(m/s) is the line continuum level minus line center level velocity difference

  30. comparison UNNOFIT 9 parameters / UNNOFIT 10 parameters UNNOFIT 10 parameters (including asymmetry) V= 1.1 km/s UNNOFIT 9 parameters (symmetrical profiles)

  31. VELOCITY GRADIENT with this empirical law, UNNOFIT is enabled to treat asymmetric profiles the convergence is quicker tests: OK histogram output–input output vs input

  32. VELOCITY GRADIENT 26 August 2006 UNNOFIT 10 parameters UNNOFIT 9 parameters field horizontality (angle between the vector and the horizontal plane) field strength (global)

  33. VELOCITY GRADIENT 26 August 2006 map of the velocity gradient V

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