Kinematics and stellar population of NGC 4486A

Abstract

Context. 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.
Aims: We study its large-scale kinematics and stellar population along the major axis to investigate the link between the nuclear and global properties.
Methods: We use long-slit medium-resolution optical spectra that we fit against stellar population models.
Results: 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^-1 at 1.3″ from the centre and decreases outwards. The rotation velocity reaches a maximum V_{max gtrapprox 115±5} km s^-1 at a radius 1.3 < r_max < 2″.
Conclusions: 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.