Kinematics and stellar population of NGC 4486A

TL;DR

This study analyzes the kinematics and stellar populations of NGC 4486A, revealing a uniformly old age, a metallicity gradient, and typical elliptical galaxy dynamics, with no evidence of past accretion events.

Contribution

It provides detailed measurements of the galaxy's stellar population and kinematic profiles, linking nuclear and global properties with high-resolution spectra.

Findings

Stellar age is approximately 12 Gyr throughout the galaxy.

Metallicity decreases from near-solar at the center to sub-solar outward.

Velocity dispersion and rotation profiles are consistent with typical low-luminosity ellipticals.

Abstract

NGC 4486A is a low-luminosity elliptical galaxy harbouring an edge-on nuclear disk of stars and dust. It is known to host a super-massive black hole. We study its large-scale kinematics and stellar population along the major axis to investigate the link between the nuclear and global properties. We use long-slit medium-resolution optical spectra that we fit against stellar population models. The SSP-equivalent age is about 12 Gyr old throughout the body of the galaxy, and its metallicity decreases from [Fe/H] = 0.18 near the centre to sub-solar values in the outskirts. The metallicity gradient is -0.24 dex per decade of radius within the effective isophote. The velocity dispersion is 132+-3 km/s at 1.3 arcsec from the centre and decreases outwards. The rotation velocity reaches a maximum V_max >~ 115+-5 km/s at a radius 1.3 < r_max < 2 arcsec. NGC\,4486A appears to be a typical low-luminosity elliptical galaxy. There is no signature in the stellar population of the possible ancient accretion/merging event that produced the disk.