Peanut-shaped bulges in face-on disk galaxies

TL;DR

This study uses high-resolution spectroscopy of face-on galaxies to detect box/peanut-shaped bulges, confirming theoretical predictions about their spectral signatures and distribution in barred galaxies.

Contribution

It provides observational evidence supporting the spectral signature of B/P bulges in face-on galaxies, validating prior theoretical models.

Findings

NGC 1703 shows no B/P bulge signature.

NGC 98 exhibits a double minimum in h_4 indicating a B/P bulge.

NGC 600 lacks a significant B/P shape.

Abstract

We present high resolution absorption-line spectroscopy of 3 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 the prediction of Debattista et al. (2005) that face-on B/P-shaped bulges can be recognized by a double minimum in the profile of the fourth-order Gauss-Hermite moment h_4. In NGC 1703, which is an unbarred control galaxy, we found no evidence of a B/P bulge. In NGC 98, a clear double minimum in h_4 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 a significant B/P shape.