Velocity fits for galaxies #1, #2, and #3 (from top to bottom). Left: SDSS RGB image overlapped with the 3, 9, 15×rms surface brightness contours at 144 (blue) and 400 MHz (orange) and the sampling regions (green ellipses). The dashed region marks the reference center of the galaxy. Right: flux density (top) and spectral index (bottom) trends with the distance from the stellar disk, and the corresponding best-fit profiles. The color-filled area indicates the 1σ confidence region. The horizontal dashed line indicates α = −0.6.