View Full Version : Microlensing Quirk

2009-Nov-30, 03:09 PM
A Puzzle Involving Galactic Bulge Microlensing Events

We study a sample of 16 microlensed Galactic bulge main sequence turnoff region stars for which high dispersion spectra have been obtained with detailed abundance analyses. We demonstrate that there is a very strong and highly statistically significant correlation between the maximum magnification of the microlensed bulge star and the value of the [Fe/H] deduced from the high resolution spectrum of each object. Physics demands that this correlation, assuming it to be real, be the result of some sample bias. We suggest several possible explanations, but are forced to reject them all,and are left puzzled. To obtain a reliable metallicity distribution in the Galactic bulge based on microlensed dwarf stars it will be necessary to resolve this issue through the course of additional observations.

Assuming there is not a screw up somewhere, this is an important paper. There should not be a correlation between chemistry and gravitational lensing; so one or more assumptions about gravitational lensing and/or spectral distributions are wrong. How might the mass, or apparent mass of the system bias the spectral distribution? This is a great enigma!