The relation between GC systems and SMBH in spiral galaxies: The link to the M• - M* correlation

We explore the relationship between globular cluster total number, N_GC, and central black hole mass, M_•, in spiral galaxies. Including cosmic scatter, log M_• ∝ (1.64 ± 0.24) log N_GC. Whereas in ellipticals the correlation is linear [log M_• ∝ (1.02 ± 0.10) log N_GC], and hence could be due to statistical convergence through mergers, this mechanism cannot explain the much steeper correlation in spirals. Additionally, we derive total stellar galaxy mass, M_*, from its two-slope correlation with N_GC (Hudson et al. 2014). In the M_• versus M_* parameter space, with M_* derived from N_GC, M_• ∝ (1.48 ± 0.18) log M_* for ellipticals, and M_• ∝ (1.21 ± 0.16) log M_* for spirals. The observed agreement between ellipticals and spirals may imply that black holes and galaxies co-evolve through "calm" accretion, AGN feedback and other secular processes.