Confirmation of a kinematic diagnostic for face-on box/peanut-shaped bulges

We present the results of high-resolution absorption-line spectroscopy of three face-on galaxies, NGC 98, NGC 600, and NGC 1703, with the aim of searching for box/peanut (B/P) shaped bulges. These observations test and confirm, for the first time, the prediction that face-on B/P-shaped bulges can be recognized by two minima in the profile along the bar's major axis of the fourth Gauss-Hermite moment h4 of the line-of-sight velocity distribution (LOSVD). In NGC 98, a clear double minimum in h4 is present along the major axis of the bar and before the end of the bar, as predicted. In contrast, in NGC 600, which is also a barred galaxy but lacks a substantial bulge, we do not find any significant kinematic signature for a B/P-shaped bulge. In NGC 1703, which is an unbarred control galaxy, we found no evidence of a B/P bulge. We also show directly that the LOSVD is broader at the location of the h4 minimum in NGC 98 than elsewhere. This more direct method avoids possible artifacts associated with the degeneracy between the measurement of LOSVD and h4.