2016/01/11 by Iskren Y. Georgiev, Torsten Böker, Natan Leigh +2
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stw093
Accepted in MNRAS, full version of Table A1 is available. 23 pages, 9 figures, Two tables
arxiv created 2016/01/11 · arxiv updated 2016/02/17
Galactic nuclei typically host either a Nuclear Star Cluster (NSC, prevalent in galaxies with masses \lesssim 1010M_\odot) or a Massive Black Hole (MBH, common in galaxies with masses \gtrsim 1012M_\odot). In the intermediate mass range, some nuclei host both a NSC and a MBH. In this paper, we explore scaling relations between NSC mass (\cal M\rm NSC) and host galaxy total stellar mass (\cal M⋆,\rm gal) using a large sample of NSCs in late- and early-type galaxies, including a number of NSCs harboring a MBH. Such scaling relations reflect the underlying physical mechanisms driving the formation and (co)evolution of these central massive objects. We find ∼ 1.5σ significant differences between NSCs in late- and early-type galaxies in the slopes and offsets of the relations r\rm eff,NSC--\cal M\rm NSC, r\rm eff, NSC--\cal M⋆,\rm gal and \cal M\rm NSC--\cal M⋆,\rm gal, in the sense that i) NSCs in late-types are more compact at fixed \cal M\rm NSC and \cal M⋆,\rm gal; and ii) the \cal M\rm NSC--\cal M⋆,\rm gal relation is shallower for NSCs in late-types than in early-types, similar to the \cal M\rm BH--\cal M⋆,\rm bulge relation. We discuss these results in the context of the (possibly ongoing) evolution of NSCs, depending on host galaxy type. For NSCs with a MBH, we illustrate the possible influence of a MBH on its host NSC, by considering the ratio between the radius of the MBH sphere of influence and r\rm eff, NSC. NSCs harbouring a sufficiently massive black hole are likely to exhibit surface brightness profile deviating from a typical King profile.