Using 3D Spectroscopy to Probe the Orbital Structure of Composite Bulges

TL;DR

This paper uses 3D spectroscopy and dynamical modeling to analyze the orbital structures of composite bulges in nearby galaxies, revealing the coexistence of classical bulges and pseudobulges.

Contribution

It introduces a method combining 3D spectroscopy with Schwarzschild modeling to distinguish different bulge components within galaxies.

Findings

Discovered coexistence of classical bulges and pseudobulges in the same galaxy.

Successfully disentangled stellar orbital structures of different bulge components.

Provided insights into the kinematic properties of composite bulges.

Abstract

Detailed imaging and spectroscopic analysis of the centers of nearby S0 and spiral galaxies shows the existence of "composite bulges", where both classical bulges and disky pseudobulges coexist in the same galaxy. As part of a search for supermassive black holes in nearby galaxy nuclei, we obtained VLT-SINFONI observations in adaptive-optics mode of several of these galaxies. Schwarzschild dynamical modeling enables us to disentangle the stellar orbital structure of the different central components, and to distinguish the differing contributions of kinematically hot (classical bulge) and kinematically cool (pseudobulge) components in the same galaxy.