EROS and MACHO Combined Limits on Planetary Mass Dark Matter in the Galactic Halo

Abstract

The EROS and MACHO collaborations have each published upper limits on the amount of planetary mass dark matter in the Galactic Halo obtained from gravitational microlensing searches. In this paper the two limits are combined to give a much stronger constraint on the abundance of low mass MACHOs.

Figures (4)

• Figure 1: The locations (J2000) of the MACHO fields used in this analysis and the location of the EROS field (thick line).
• Figure 2: Total number of expected events versus lens mass for the combined MACHO and EROS results. The five EROS models are shown on the top plot and the eight MACHO models are shown on the bottom. Also shown in the top plot is the contribution to the results for model 1 from the EROS results (thin dotted line) and the MACHO results (dot-dash line). The relative contributions are roughly the same for all models.
• Figure 3: Halo fraction upper limit (95% c.l.) versus lens mass for the five EROS models (top) and the eight MACHO models (bottom). The line coding is the same as in Figure 2.
• Figure 4: Upper limit (95% c.l.) on total halo mass in MACHOs versus lens mass for the five EROS models (top) and the eight MACHO models (bottom). The line coding is the same as in Figure 2.