Mapping the stellar age of the Milky Way bulge with the VVV

II. Deep JK_s catalog release based on PSF photometry^⋆⋆⋆

¹ Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna, 4860 Santiago, Chile
e-mail: frsurot@uc.cl
² European Southern Observatory, Karl Schwarzschild-Straße 2, 85748 Garching bei München, Germany
e-mail: evalenti@eso.org
³ Excellence Cluster ORIGINS, Boltzmann-Straße 2, 85748 Garching bei München, Germany
⁴ Instituto de Astrofisica de Canarias, Via Lacteas S/N, 38200 La Laguna, Tenerife, Spain
⁵ Department of Astrophisics, University of La Laguna, 38200 La Laguna, Tenerife, Canary Islands, Spain
⁶ Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
⁷ UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁸ Departamento de Ciencias Fisícas, Universidad Andrés Bello, República, 220 Santiago, Chile
⁹ Vatican Observatory, 00120 Vatican City, Italy
¹⁰ Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK

Received: 18 April 2019
Accepted: 28 June 2019

Abstract

Context. The bulge represents the best compromise between old and massive Galactic components, and as such its study is a valuable opportunity to understand how the bulk of the Milky Way formed and evolved. In addition, being the only bulge in which we can individually resolve stars in all evolutionary sequences, the properties of its stellar content provide crucial insights into the formation of bulges.

Aims. We are providing a detailed and comprehensive census of the Milky Way bulge stellar populations by producing deep and accurate photometric catalogs of the inner ∼300 deg² of the Galaxy.

Methods. We performed DAOPHOT/ALLFRAME point spread function (PSF) fitting photometry of multi-epochs J and K_s images provided by the VISTA Variables in the Vía Láctea (VVV) survey to obtain deep photometric catalogs. Artificial star experiments have been conducted on all images to properly assess the completeness and the accuracy of the photometric measurements.

Results. We present a photometric database containing nearly 600 million stars across the bulge area surveyed by the VVV. Through the comparison of derived color-magnitude diagrams of selected fields representative of different levels of extinction and crowding, we show the quality, completeness and depth of the new catalogs. With the exception of the fields located along the plane, this new photometry samples stars down to ∼1–2 mag below the old main sequence turnoff with unprecedented accuracy. To demonstrate the tremendous potential inherent to this new dataset, we give a few examples of possible applications, including (i) star count studies through the dataset completeness map; (ii) surface brightness map; and (iii) cross-correlation with Gaia DR2.

Conclusions. The database presented here represents an invaluable collection for the whole community, and we encourage its exploitation. The photometric catalogs including completeness information are publicly available through the ESO Science Archive as part of the MW-BULGE-PSPHOT release.