@article{a15fe876f743413ba775536c0f580dae,
title = "Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS {\^a}†: III. the first global photometric metallicity map of the Galactic bulge",
abstract = "Aims. We investigate the large-scale metallicity distribution in the Galactic bulge using large spatial coverage to constrain the bulge formation scenario. Methods. We use the VISTA variables in the Via Lactea (VVV) survey data and 2MASS photometry, which cover 320 sqdeg of the Galactic bulge, to derive photometric metallicities by interpolating the (J - Ks)0 colors of individual red giant branch stars based on a set of globular cluster ridge lines. We then use this information to construct the first global metallicity map of the bulge with a resolution of 30′ × 45′. Results. The metallicity map of the bulge revealed a clear vertical metallicity gradient of ∼0.04 dex/deg (∼0.28 dex/kpc), with metal-rich stars ([Fe/H] ∼ 0) dominating the inner bulge in regions closer to the Galactic plane (|b| < 5). At larger scale heights, the mean metallicity of the bulge population becomes significantly more metal poor. Conclusions. This fits in the scenario of a boxy bulge originating from the vertical instability of the Galactic bar, formed early via secular evolution of a two-component stellar disk. Older metal-poor stars dominate at higher scale heights due to the non-mixed orbits of originally hotter thick disk stars.",
keywords = "Galaxy: abundances, Galaxy: bulge, Galaxy: formation, Stars: abundances",
author = "Gonzalez, {O. A.} and M. Rejkuba and M. Zoccali and E. Valent and D. Minniti and R. Tobar",
note = "Funding Information: We thank the referee, David Nataf, for a careful review and valuable comments that contributed to the improvement of the article. We warmly thank Alvio Renzini and Vanessa Hill for providing useful comments and suggestions to this work. We are grateful to Inma Martinez-Valpuesta and Ortwin Gerhard for sharing their model results before publication. We gratefully acknowledge use of data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope and data products from the Cambridge Astronomical Survey Unit. We acknowledge funding from the FONDAP Center for Astrophysics 15010003, the BASAL CATA Center for Astrophysics and Associated Technologies PFB-06, the MILENIO Milky Way Millennium Nucleus from the Ministry of Economycs ICM grant P07-021-F and Proyectos FONDECYT Regular 1110393 and 1090213. M.Z. is also partially supported by Proyecto Anillo ACT-86. This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). It uses data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. We warmly thank the ESO Paranal Observatory staff for performing the observations.",
year = "2013",
doi = "10.1051/0004-6361/201220842",
language = "English",
volume = "552",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
}