Oscar A. Gonzalez PhD ESO-Garching 3rd Subaru conference: Galactic Archaeology, Deep field and the formation of the Milky Way, Japan, 2011

The Milky Way bulge seems to be very complex (or we are just very confused…) Structure X-shape outer regions |b|>5 Saito+2011, McWilliam+2010, Nataf+2010 Ages Dominated by old populations? Clarkson+2008 (and many others ) Significant population of younger stars? Bensby+2011 Bensby et al McWilliam & Zoccali 2010

Hill et al (also Bensby+2011) Babusiaux et al 2010 (also Soto+2007) (also Soto+2007) Structure X-shape outer regions |b|>5 Saito+2011, McWilliam+2010, Nataf+2010 Ages Dominated by old populations? Clarkson+2008 (and many others ) Bensby+2011 Stellar abundances mixed populations? Two peaks in the MDF with different kinematics Possible evidence for a classical spheroid + bar The Milky Way bulge seems to be very complex

Stellar abundances mixed populations Alpha-element abundances (Ca, Mg, Ti, Si) by spectral synthesis from FLAMES-GIRAFFE spectra of 650 K giants in 4 Bulge fields and a homogeneous comparison with 40 disk giants Metal-poor Bulge:  -enhanced as the thick disk Metal-rich Bulge:  -poor as the thin disk Gonzalez et al. 2011a

Three fields along the minor axis: b = -4, -6 and -12 Metal–poor component shows no variations in  -enhancement Stellar abundances mixed populations Gonzalez et al. 2011a Johnson et al. 2011

A large coverage is required in order to obtain the global picture of the Bulge The mapping problem VISTA variables in the Via Lactea (VVV) public survey 1 full multi-band mapping + 5 year epochs in Ks for variability campaign

A method for extinction, structure and metallicity maps Difference between the red clump color in BW and any field is a function of reddening Build the Luminosity function to study the K s distribution of red clump giants Photometric metallicities from CMDs in the absolute plane (J-K s ) 0 Interpolation between GC ridge lines with known [Fe/H] Gonzalez et al. 2011b

A method for extinction, structure and metallicity maps Extinction maps for the outer bulge and the very inner regions with up to 3’ resolution Metallicity maps which trace the minor axis gradient observed in HR studies Gonzalez et al. 2011b

Extinction maps for the outer bulge and the very inner regions with up to 3’ resolution Web tool to obtain extinction values. Link available soon at the VVV survey page A method for extinction, structure and metallicity maps

VVV data allows to trace the photometric properties of the RC in order to: VVV data allows to trace the photometric properties of the RC in order to: Obtain extinction maps sensitive to small scale variations Trace the Bulge structure (X-shape, bar, inner structure) Measure photometric metallicity distributions which resemble spectroscopic measurements Trace the bulge metallicity gradients. All this coupled with: HR and LR in several fields to measure [Fe/H] and [  /Fe] Comparison to recent bulge formation models Unfold the formation history of the Milky Way Bulge