The nuclear star cluster of the Milky Way

Abstract

The nuclear star cluster of the Milky Way is a unique target in the Universe. Contrary to extragalactic nuclear star clusters, using current technology it can be resolved into tens of thousands of individual stars. This allows us to study in detail its spatial and velocity structure as well as the different stellar populations that make up the cluster. Moreover, the Milky Way is one of the very few cases where we have firm evidence for the co-existence of a nuclear star cluster with a central supermassive black hole, Sagittarius A*. The number density of stars in the Galactic center nuclear star cluster can be well described, at distances $\gtrsim 1$ pc from Sagittarius A*, by a power-law of the form $\rho (r)\propto r^{-\gamma }$ with an index of $\gamma \approx 1.8$. In the central parsec the index of the power-law becomes much flatter and decreases to $\gamma \approx 1.2$. We present proper motions for more than 6000 stars within 1 pc in projection from the central black hole. The cluster appears isotropic at projected distances $\gtrsim 0.5$ pc from Sagittarius A*. Outside of 0.5 pc and out to 1.0 pc the velocity dispersion appears to stay constant. A robust result of our Jeans modeling of the data is the required presence of $0.5-2.0\times 10^6{M}_{\odot }$ of extended (stellar) mass in the central parsec of the Galaxy.

To appear in the proceedings of "The Universe under the Microscope - Astrophysics at High Angular Resolution", Journal of Physics:Conference Series (IOP; http://www.iop.org/EJ/conf) This version has been slightly modified (e.g. double-log plot in right hand panel of Figure 5)

References in corpus (10)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
• A Fundamental Relation Between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies
• The structure of the nuclear stellar cluster of the Milky Way
• Stellar populations in the nuclei of late-type spiral galaxies
• From Supermassive Black Holes to Dwarf Elliptical Nuclei: a Mass Continuum
• Evidence for a Long-Standing Top-Heavy IMF in the Central Parsec of the Galaxy
• The distance to the Galactic Centre based on Population-II Cepheids and RR Lyrae stars
• The Discovery of an Active Galactic Nucleus in the Late-type Galaxy NGC 3621: Spitzer Spectroscopic Observations
• An Accreting Black Hole in the Nuclear Star Cluster of the Bulgeless Galaxy NGC 1042

Cited by in corpus (9)

• Quantifying the Coexistence of Massive Black Holes and Dense Nuclear Star Clusters
• Dissipationless Formation and Evolution of the Milky Way Nuclear Star Cluster
• The Distribution of Stars and Stellar Remnants at the Galactic Center
• Origin and growth of nuclear star clusters around massive black holes
• A review of elliptical and disc galaxy structure, and modern scaling laws
• The Nuclear Cluster of the Milky Way: Total Mass and Luminosity (long version)
• A new channel to form IMBHs throughout cosmic time
• Orbits Around Black Holes in Triaxial Nuclei
• Can supernova shells feed supermassive black holes in galactic nuclei?