GW8 - Dense stellar environments as sites of gravitational wave emission |
|
Speaker |
Navarro, Maria Gabriela |
|
Coauthors |
Minniti, Dante; Contreras-Ramos, Rodrigo |
| Talk Title |
Microlensing events in the Galactic bulge |
|
Abstract |
The formation of the Galaxy, especially the bulge is a question that has not yet been resolved. The most accurate way to achieve this is comparing the different proposed theoretical models of formation and evolution of the bulge with the observational data. The only manner to study the inner part of the galactic bulge, where the extinction and crowding is severe, is using IR observations such as the VVV Survey data. In this work the search or microlensing events in the inner parti of the bulge was done for the first time. We have detected 630 microlensing events within an area of 20.68deg2 around the galactic center (−10.00 ≤ l ≤ 10.44 deg and −0.46 ≤ b ≤ 0.65 deg). The Einstein ring crossing time is the only parameter which has a physical meaning and is degenerate thus can only be studied statistically in large numbers including in the calculations the distributions of the parameters involved which require models of the Milky Way. In this case, the proper motions distribution of different galactic populations can be useful to interpret the results. Furthermore, the microlensing optical depth (τ) is the fraction of the sky covered by the Einstein ring disks of the lenses for a given source population, and it is directly related to the mass density of compact objects along the line of sight. This indicator is not currently known but is expected to increase towards the Galactic center. From the comparison of the observed distributions with theoretical models it will be possible to obtain in a self-dependent way features of the bulge structure reaching the central parts of the Milky Way to create the 3D picture of the Galaxy. Besides the statistical study of the complete sample of microlensing events, the study of specific events became attractive. The long timescale events favor the presence of dark stellar remnants such as black holes and neutron stars. Gravitational microlensing is the only method capable of finding isolated stellar-mass remnants and deriving their masses and the mass function. Black holes and neutron star population are important ingredients in our understanding of stellar evolution, mass distribution, galaxy evolution and structure, dark matter balance, etc. From simulations we expect a population of stellar mass black holes that increase toward the center. |
|
Talk view |
|
|
|
|