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Interpretation of EROS Microlensing Data toward Spiral Arms

Sohrab Rahvar Sharif University of Technology Marc Moniez LAL-CNRS. Interpretation of EROS Microlensing Data toward Spiral Arms. EROS Seven Season Result ( arXiv:0901.1325 ) :. 12.9 Million stars monitored in 4 directions of spiral arms 27 microlensing candidates

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Interpretation of EROS Microlensing Data toward Spiral Arms

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  1. SohrabRahvarSharif University of TechnologyMarc MoniezLAL-CNRS Interpretation of EROS Microlensing Data toward Spiral Arms 13th Gravitational Microlensing Workshop-January 2009 -Paris

  2. EROS Seven Season Result (arXiv:0901.1325 ) : 12.9 Million stars monitored in 4 directions of spiral arms 27 microlensing candidates τ estimated from the 22 best events (u0<0.7) Distance distribution of source stars wide and poorly known-> Catalog optical depth EROS catalog almost complete for -> Corresponding optical depth 13th Gravitational Microlensing Workshop-January 2009 -Paris

  3. Optical Depth assuming source at a given distance from the observer 13th Gravitational Microlensing Workshop-January 2009 -Paris

  4. Procedure EROS efficiencies 13th Gravitational Microlensing Workshop-January 2009 -Paris

  5. Model • Double Exponential model for disk plus bar with bar-inclination and dust abundance to be fitted. • Chabrier (2004) IMF • Hipparcos data to determine the local CM diagram. • Extinction model 13th Gravitational Microlensing Workshop-January 2009 -Paris

  6. Galactic Model (1) Disk Model Bulge Model 13th Gravitational Microlensing Workshop-January 2009 -Paris

  7. Galactic Model (2) Light absorption proportional to H column density will be fitted. φcould be fitted. φ 13th Gravitational Microlensing Workshop-January 2009 -Paris

  8. Stellar Mass function 13th Gravitational Microlensing Workshop-January 2009 -Paris

  9. Hipparcos Data ~ 120,000 star Hipparcos CM diagram red = stars <50 pc Isotropy of stars within 50 pc Hyades open cluster 13th Gravitational Microlensing Workshop-January 2009 -Paris

  10. Debiased local CM distribution Hipparcos stars within < 50 pc Distribution of stars in Hipparcoscomplete until mv<7.5 Distribution after debiasing and extrapolation. Color extrapolated from the color vsmag relation for faint stars: Hipparcos complete until 50 pc Hipparcos complete until d(completion) Not enough faint stars around sun Debiased local density of stars Debiasing Extrapolation 13th Gravitational Microlensing Workshop-January 2009 -Paris

  11. Star Detection Efficiency From the local CM diagram to the EROS observed catalog Detection efficiency of EROS as a function of B(EROS) from HST images 13th Gravitational Microlensing Workshop-January 2009 -Paris

  12. Synthesized CMD toward γsct EROS catalog Synthetic Catalog 13th Gravitational Microlensing Workshop-January 2009 -Paris

  13. Optical Depth predictions Integrated along the line of sight & averaged on EROS catalog (Catalog optical depth) Smodelis the simulated stellar density 13th Gravitational Microlensing Workshop-January 2009 -Paris

  14. Fitting model with EROS data Expresses the difference between the model and the observations Here we choose to fit and we found the best agreement between data and model with f ~ 6 % (to be finalized) 13th Gravitational Microlensing Workshop-January 2009 -Paris

  15. Perspectives - Consider simulated and observed mag and color distributions (not only average values) in the fit - Also consider simulated and observed tEdistributions - Use absorption maps (Besancon model) - Include observations towards Galactic center 13th Gravitational Microlensing Workshop-January 2009 -Paris

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