astrolunch: Gary Mamon

Tue, 01/06/202112:30-13:30

Mass-orbit modeling of galaxy & star clusters: orbital shapes by galaxy type and an inner concentration of stellar black holes in a nearby globular cluster

I apply the bayesian mass-orbit modeling of internal kinematics code, MAMPOSSt, to both galaxy clusters and globular star clusters. Our analysis of stacks of 54 nearby regular galaxy clusters from the WINGS survey, totaling nearly 5000 galaxy line-of-sight velocities, allows us to measure the average dark matter mass density profile and compare its shape and concentration to the predictions from dissipationless cosmological simulations, as well as to measure the shapes of the orbits in the inner and outer regions. I will discuss the physical models explaining the results. Globular clusters are close enough to also have plane-of-sky velocities measured from their proper motions. Using over 7000 HST and Gaia stellar proper motions in the nearby core-collapsed globular cluster, NGC 6397, I infer sharp constraints on the orbital shapes and mass excess at the center, and discuss whether the inner mass is caused from an intermediate-mass black hole or from a collection of stellar remnants.