AAS 198th Meeting, June 2001
Session 37. Gravitational Lenses, Relativistic Astrophysics
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

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[37.02] Microlensing and Stellar Remnants

L.V.E. Koopmans (Caltech), R.D. Blandford (Caltech), A.G. de Bruyn (NFRA), C.D. Fassnacht (STScI), J. Wambsganss (Potsdam University)

Galactic microlensing results from the MACHO, EROS and OGLE collaborations suggest that a significant fraction (~20%) of the dark-matter halo inside 50~kpc might be composed of massive compact objects with typical masses of ~0.6~M\odot. Direct searches for high proper-motion objects in the solar neighborhood and HDF suggest that these objects could be white dwarfs, although a high mass fraction posses substantial problems for standard star-formation models.

We present new VLA multi-frequency radio observations of the edge-on spiral gravitational lens B1600+434 at a redshift z=0.41. They show strong non-intrinsic variations in the lensed image that passes predominantly through the dark-matter halo around the lens galaxy. We argue that these variations are the result of microlensing.

The halo line-of-sight in Galactic microlensing observations and that in B1600+434 are similar, allowing for a unique comparison of these fully independent results from two spiral galaxies. We present results of this comparison and discuss whether the microlensing populations in B1600+434 and our Galaxy, and the population of high proper-motion objects can be the same.

If you would like more information about this abstract, please follow the link to http://www.its.caltech.edu/~koopmans. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: leon@tapir.caltech.edu

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