Stacked spectral index map (S ∝ ν^+α) combining 19 22 GHz (blue dash-dotted contour) and 43 GHz (black contours) images between 2005 and 2009. A cut along the direction of the jets is shown in the lower panels, depicting the flux density profile and spectral index along the jet axis (see line in top panel). The blue star indicates the assumed location of the dynamical center. The contours of the 43 GHz map start at 5 times the noise level and increase logarithmically by factors of 2. For the 22 GHz map only one countour at 5 times the noise level is shown.