Central K-band kinematics and line strength maps of NGC 1399

TL;DR

This study provides high-resolution K-band maps of NGC 1399, revealing complex central kinematic and spectral features, including a velocity dispersion dip and line strength variations, indicating a dynamically cold subsystem at the galaxy's core.

Contribution

First high-resolution K-band maps of NGC 1399's central region, revealing new kinematic and spectral structures and suggesting a distinct stellar population in the core.

Findings

Detection of a central velocity dispersion dip within 0.2"

Identification of non-symmetric sigma peaks around the center

Observation of line strength drops in Na I and CO(2-0) in the nucleus

Abstract

In this paper we present for the first time high spatial resolution K-band maps of the central kinematical and near-infrared spectral properties of the giant cD galaxy in the Fornax cluster, NGC 1399. We confirm the presence of a central velocity dispersion dip within radius < 0.2" seen in previous long-slit studies. Our velocity dispersion maps give evidence for a non-symmetric structure in this central area by showing three sigma peaks to the north-east, south-east and west of the galaxy centre. Additionally we measure near-IR line strength indices at unprecedented spatial resolution in NGC 1399. The most important features we observe in our 2-dimensional line strength maps are drops in Na I and CO(2-0) line strength in the nuclear region of the galaxy, coinciding spatially with the drop in sigma. The observed line strength and velocity dispersion changes suggest a scenario where the centre of NGC 1399 harbours a dynamically cold subsystem with a distinct stellar population.