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UNNOFIT inversion V. Bommier, J. Rayrole, M. Martínez González, G. Molodij Paris-Meudon Observatory (France) THEMIS Atelier "Inversion et transfert multidimensionnel", Beaulieu sur mer, France, 8-10 Octobre 2007
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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)
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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) typical INTRANETWORK low polarized pixel
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UNNOFIT Present work: introduction of a 9 th fitted parameter: the magnetic filling factor Skumanich & Lites (1987): I nm constant (average of the observation) our work: same physical conditions (except the magnetic field) for I nm and I m I nm varies throughout the map (umbra, penumbra, plages, faculæ, quiet, etc...) 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
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UNNOFIT minimum of per pixel for two varying parameters: – the magnetic field intensity – the magnetic filling factor full scale: the polarimetric sensitivity
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UNNOFIT minimum of per pixel for two varying parameters: – the magnetic field inclination – the magnetic field azimuth full scale: the polarimetric sensitivity
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noise level measurement by wavelet filtering technique and determination of the standard deviation
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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.
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histograms of the differences inverted-initial (UNNOFIT accuracy) (input) B >= 45G NETWORK (input) B < 45G INTER- NETWORK
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comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 8 parameters (no filling factor) B lim = 100 Gauss UNNOFIT 9 parameters (with filling factor) B lim = 20 Gauss
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Accuracy
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Orders of magnitude no filling factor ( = 1) with filling factor ( 1)
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comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 8 parameters (no filling factor) UNNOFIT 9 parameters (with filling factor)
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comparison UNNOFIT 8 parameters / UNNOFIT 9 parameters UNNOFIT 8 parameters (no filling factor) UNNOFIT 9 parameters (with filling factor)
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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
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comparison unsymmetrised / symmetrised unsymmetrised (no recentering before subtraction) symmetrised (with recentering before subtraction) QUIET SUN 25 July 2007 TIP-TILT ON pixel size 0.2 arcsec
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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
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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)
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INITIALISATION OF UNNOFIT WITH PCA RESULTS PCA initialisation neighbour initialisation difference with the "normal" (i.e., non accelerated) solution
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INITIALISATION OF UNNOFIT WITH PCA RESULTS PCA initialisation 22.0% of "bad" pixels neighbour initialisation 1.2% of "bad" pixels 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:
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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 UNNOFIT PCA
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COMPARISON UNNOFIT/PCA UNNOFIT PCA inclination angle with the horizontal plane
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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
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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
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UNNOFIT/SIR Comparison : Sunspot field strength inclinationazimuth differences in
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UNNOFIT/SIR Comparison : Quiet Sun inclinationazimuth differences in field strength
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Validity of the Milne-Eddington Approximation logarithmic linear Linearity of the source function at 1 NLTE computation of the source function in a VALC atmosphere Fe I 6302.5 Å opacity
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VELOCITY GRADIENT Observation by J. RAYROLE concerns the line bisector I+V I-V 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 )
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VELOCITY GRADIENT Empirical law by J. RAYROLE and G. MOLODIJ absorption coefficient (that enters the Unno-Rachkowsky solution): modification of UNNOFIT to determine a 10 th parameter, V V (m/s) is the line continuum level minus line center level velocity difference
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comparison UNNOFIT 9 parameters / UNNOFIT 10 parameters UNNOFIT 9 parameters (symmetrical profiles) UNNOFIT 10 parameters (including asymmetry) V = 1.1 km/s
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VELOCITY GRADIENT with this empirical law, UNNOFIT is enabled to treat asymmetric profiles the convergence is quicker tests: OK output vs input histogram output–input
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VELOCITY GRADIENT 26 August 2006 UNNOFIT 9 parameters UNNOFIT 10 parameters field horizontality (angle between the vector and the horizontal plane) field strength (global)
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VELOCITY GRADIENT 26 August 2006 map of the velocity gradient V
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