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The nuclear cluster of the Milky Way: total mass and luminosity

Published online by Cambridge University Press:  22 May 2014

T. K. Fritz
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904-4325, email: tkf4w@virginia.edu
S. Chatzopoulos
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
O. Gerhard
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
S. Gillessen
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
R. Genzel
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany Department of Physics, University of California, Berkeley, 366 Le Comte Hall, Berkeley, CA 94720-7300
O. Pfuhl
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
S. Tacchella
Affiliation:
Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093, Zurich, Switzerland
F. Eisenhauer
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
T. Ott
Affiliation:
Max Planck Institut für Extraterrestrische Physik, Postfach 1312, D-85741, Garching, Germany
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Abstract

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Here we present the fundamental properties of the nuclear cluster of the Milky Way. First, we derive its structural properties by constructing a density map of the central 1000″ using extinction-corrected star counts. We can describe the data with a two-component model built from Sersic profiles. The inner nearly spherical component is the nuclear cluster. The outer, strongly flattened component can be identified with the stellar component of the circumnuclear zone. Second, we enlarge the radius inside which detailed dynamics are available from 1 pc to 4 pc. We use more than 10000 individual proper motions and more than 2700 radial velocities. We determine the cluster mass by means of isotropic spherical Jeans modeling. We get a nuclear cluster mass within 100″ of M100″=(6.11 ± 0.52|fix R0±0.97|R0) × 106 M, which corresponds to a total cluster mass of MNC=(13.08 ± 2.51|fix R0± 2.08|R0) × 106 M. By combination of our mass with the flux we calculate M/L=0.50 ± 0.12 M/L⊙,Ks for the central 100″. That is broadly consistent with a Chabrier IMF. With its mass and a luminosity of MKs=−15.30±0.26 the nuclear cluster is a bright and massive specimen with a typical size.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

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