Stellar density profile and mass of the Milky Way Bulge from VVV data

TL;DR

This paper provides the first detailed stellar density profile of the Milky Way bulge using VVV survey data, linking star counts to kinematic data to estimate the bulge's stellar mass.

Contribution

It introduces a high-accuracy stellar density map of the bulge and offers the first empirical estimate of its stellar mass based on star counts and luminosity functions.

Findings

Stellar density profile of the Milky Way bulge derived from VVV data.

Identification of the central velocity dispersion peak with a stellar overdensity.

Empirical estimate of the bulge's stellar mass as approximately 2.0 x 10^{10} solar masses.

Abstract

We present the first stellar density profile of the Milky Way bulge reaching latitude $b=0^\circ$. It is derived by counting red clump stars within the colour\--magnitude diagram constructed with the new PSF-fitting photometry from VISTA Variables in the V\'\i a L\'actea (VVV) survey data. The new stellar density map covers the area between $|l|\leq 10^\circ$ and $|b|\leq 4.5^\circ$ with unprecedented accuracy, allowing to establish a direct link between the stellar kinematics from the Giraffe Inner Bulge Spectroscopic Survey (GIBS) and the stellar mass density distribution. In particular, the location of the central velocity dispersion peak from GIBS matches a high overdensity 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 remnants of the Galactic bulge. The Milky Way bulge stellar mass within ($|b|<9.5^\circ$, $|l|<10^\circ$) is $2.0\pm0.3\times 10^{10}M_{\odot}$.