Searching for MACHOs in Galaxy Clusters

Abstract

If cluster dark matter is in the form of compact objects it will introduce fluctuations into the light curves of distant sources. Current searches for MACHOs in clusters of galaxies focus on monitoring quasars behind nearby systems. This paper considers the effect of such a compact population on the surface brightness distribution of giant gravitationally lensed arcs. As the microlensing optical depth is significant in these clusters, the expected fluctuations are substantial and are observable. Focusing on the giant arc seen in Abell 370, we demonstrate that several `extreme' events would be visible in a comparison of HST observations at two epochs. Utilizing NGST, long term monitoring should reveal a ubiquitous twinkling of brightness over the surface of the arcs.

8 pages, 2 figures, to appear in the Astrophysical Journal Letters

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Cited by in corpus (8)

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• Cluster-Cluster Microlensing as a Probe of Intracluster Stars, MACHOs, and Remnants of the First Generation Stars
• Statistical Microlensing Toward Magnified High-Redshift Star Clusters
• Empirical constraints on alternative gravity theories from gravitational lensing
• Detecting compact dark matter in galaxy clusters via gravitational microlensing: A2218 & A370
• On a systematic bias in SBF-based distances due to gravitational microlensing
• Seeing Star Formation Regions with Gravitational Microlensing