Made-to-measure Modelling of Nuclear Star Clusters

Abstract

The nuclear star clusters of late-type spiral galaxies are comprised of multiple components. Gemini near-infrared spectroscopy of the nuclear star cluster in NGC 4244 shows clear rotation. Earlier, De Lorenzi et al. (2013) constructed two component (disc + spheroid) axisymmetric three integral particle models of NGC 4244, finding a negative vertical anisotropy (βz <
0). We construct a series of axisymmetric, single-component, particle models of NGC
4244 using these data, combined with F814W band photometric data from the Hubble space telescope and the
χ2-made-to-measure code NMAGIC. We find a best fitting central black hole mass of 5 x
105 M⊙ . Our models also have a negative βz, as in earlier models. We conclude that although the disc component of NGC 4244’s nuclear star cluster is clearly present, it has a negligible effect on the measured kinematics. We also present a preliminary density model for the nuclear star cluster residing in the pure spiral galaxy M33.