Stacking results. From left to right, we show the mean-stacked UV continuum image, the mean-stacked Si II* emission image (5 arcsec each), the mean surface brightness profiles, the median-stacked UV continuum image, and the median-stacked Si II* emission image. The top and bottom panels represent stacking results of the Si II* λ1533 line (N = 13) and those of all Si II* lines (22 images for 14 sources), respectively. The cyan crosses indicate the HST center. The white contours correspond to 5 × 10⁻²⁰ erg s⁻¹ cm⁻² arcsec⁻², which is also shown by black dotted lines on the SB profiles. The SB profiles of the mean-stacked Si II* and UV continuum are indicated by the blue and black lines, respectively, while the median-stacked Si II* and UV continuum are shown by the blue and the black crosses, respectively. The blue and gray shades represent 1σ uncertainties of the SB for Si II* emission and UV continuum, respectively. Following Fig. 3, the SB profiles for the continuum are normalized at the innermost radius (R = $0\stackrel{″}{.}1$) to those for the Si II* emission. The mean and median stacked Si II* NB images show a clear extension of Si II* compared to the UV continuum on the stacked MUSE BB images, which can be confirmed with their SB profiles.