Bohdan Paczyński
Published 1994-12-14Version 1
Traditional evidence for large amount of dark matter is based on dynamical consideration for systems with $ t_{dyn} \gg t_{obs} $. Recent observational and theoretical developments in gravitational lensing offer a much more robust determination of the mass distribution in some galaxies and their clusters, with the precision comparable to that obtainable for double stars for which $ t_{dyn} < t_{obs} $, and offer independent and direct evidence for the presence of dark matter. Gravitational microlensing and femtolensing offer a possibility to detect MACHOs with masses in excess of $ \sim 10^{-15} ~ M_{\odot} $. The recent detections of microlensing events by the EROS, MACHO and OGLE teams do not require any dark lenses as ordinary low mass stars are compatible with the observations. However, these searches will soon either detect genuine MACHOs, or they will place stringent upper limits on their number density.
Comments: 8 pages, plain self-contained TEX, to appear in the Proceedings of the 5th Annual October Astrophysics Conference in Maryland: DARK MATTER, held on October 10-12, 1994 at College Park, Maryland
Mapping the Dark Matter in Clusters
Problems for MOND in Clusters and the Ly-alpha Forest
INDICATIONS OF DARK MATTER DERIVED FROM LARGE SCALE FLOWS
