Thesis Topic: The 3D structure of the Galactic Bulge


Thesis Supervisor: Elena Valenti





This project aims at providing a detailed 3D structure of the Galactic Bulge using RR Lyrae stars (RRLs) as distance indicators.

The current theoretical and empirical evidence indicates that RRLs do obey to a well defined optical (I band) and near-infrared (J,H,K) Period-Luminosity-Metallicity and Period-Wesenheit-Metallicity relations.
The use of optical and NIR mean magnitudes allow to provide individual distance determinations with an accuracy of the order of 3%. This accuracy is mandatory to constrain the geometry of the old ( age >10 Gyr) stellar population of the Galactic Bulge and to trace its density profile (central vs long Bar).

The huge RRL sample recently identified by OGLE IV in the Galactic Bulge for which accurate periods, mean V,I-band magnitudes are available will be combined with mean NIR (JHK) and MIR (3,6, 4.5 microns) magnitudes using single epoch measurements provided either by 2MASS, VVV/X and WISE survey.

The combination of optical and infrared data is crucial to estimate simultaneously the distance and the reddening and to provide a photometric determination of the metallicity.

New and accurate NIR and MIR light curve templates will be used to improve the precision of the infrared mean magnitudes. The templates will be obtained by using a large time-series photometric database of globular cluster images based on SOFI@ESO/NTT, FourStar@ Magellan (for NIR domain) and Spitzer (for MIR range).

This project is part of a collaboration network involving several institutes (ESO, Rome University, PUC, Andres Bello).

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