1999/07/07 by Andrew Gould, Gould, Andrew, Samir Salim +1
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #History and Developments in Astronomy #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9907081
Talk given at "Working on the Fringe", Dana Point, CA, May 24 1999, 5 pages
arxiv created 1999/07/07 · openalex publication_date 1999/07/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
By combining SIM observations with ground-based photometry, one can completely solve microlensing events seen toward the Galactic bulge. One could measure the mass, distance, and transverse velocity of ~100 lenses to ~5% precision in only ~500 hours of SIM time. Among the numerous applications are 1) measurement of the mass functions (MFs) of the bulge and disk 2) measurement of the relative normalizations of the bulge and disk MFs (and so their relative contribution to the Galactic potential), 3) measurement of the number of bulge white dwarfs and neutron stars (and so the initial MF well above the present turnoff). SIM astrometric measurements are simultaneously photometric measurements. SIM astrometry determines the angular size of the Einstein ring on the sky, and comparison of SIM and ground-based photometry determines the size of the Einstein ring projected onto the observer plane. Only by combining both of these measurements is it possible to completely solve the microlensing events.