Stellar density profile and mass of the Milky Way bulge from VVV data^⋆

¹ European Southern Observatory, Karl Schwarzschild-Straße 2, 85748 Garching bei München, Germany
e-mail: evalenti@eso.org
² Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile
³ Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
⁴ European Southern Observatory, A. de Cordova 3107, Casilla 19001, Santiago 19, Chile
⁵ Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
⁶ Departamento de Ciencias Fisícas, Universidad Andrés Bello, República 220, Santiago, Chile
⁷ Vatican Observatory, V 00120 Vatican City State, Italy
⁸ Unidad de Astronomía, Fac. de Ciencias Básicas, Universidad de Antofagasta, Antofagasta, Chile
⁹ Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, 35122 Padova, Italy
¹⁰ Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany

Received: 4 October 2015
Accepted: 23 October 2015

Abstract

We present the first stellar density profile of the Milky Way bulge that reaches latitude b = 0°. The profile was derived by counting red clump stars within the colour-magnitude diagram that was constructed using the new PSF-fitting photometry from VISTA Variables in the Vía Láctea (VVV) survey data. The new stellar density map covers the area between | l | ≤ 10° and | b | ≤ 4.5° with unprecedented accuracy, allowing the stellar kinematics from the Giraffe Inner Bulge Spectroscopic Survey (GIBS) to be linked to the stellar mass density distribution. In particular, the location of the central velocity-dispersion peak from GIBS matches a high over-density in the VVV star count map. By scaling the total luminosity function (LF) obtained from all VVV fields to the LF from Zoccali et al.(2003), we obtain the first fully empirical estimate of the mass in stars and in remnants of the Galactic bulge. Within (| b | < 9.5°, | l | < 10°), the Milky Way bulge stellar mass is 2.0 ± 0.3 × 10¹⁰M_⊙.