2003/03/13 by Cheongho Han, Andrew Gould · 2 citations
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/375706
published as Astrophys.J. 592 (2003) 172-175 · 10 pages, including 1 figure. Submitted to ApJ
arxiv created 2003/03/13 · arxiv updated 2009/12/01
We estimate the optical depth to self-lensing by stars in the Galactic bulge using the HST star counts of Holtzman et al and Zoccali et al as extrapolated by Gould into the brown-dwarf and remnant regimes and deprojected along the line of sight using the model of Dwek et al. We find a self-lensing optical depth tau(bulge-bulge)=0.98 x 10-6. When combined with the lensing of bulge stars by foreground stars in the disk, this yields tau(bulge-total)=1.63 x 10-6, in reasonable agreement with the estimates of tau=2.13 +/- 0.40 x 10-6 and tau=1.08 +/- 0.30 x 10-6 based on observations of clump giants by the MACHO and EROS collaborations.