Expected EAGLE Event Rate towards the Magellanic Clouds

概要

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We propose to search for MACHOs by observing EAGLE (Extremely Amplified Gravitational LEnsing) events of a majority of dim stars. This search is independent of the usual one. For the detection limit of EAGLE (〜 20 mag), 〜 100 f (τ^<LMC> /3 ×10^<-7>) (100 days/<t^^-> ) EAGLE events/y are expected to result from all the dim stars in LMC. Here τ^<LMC> and <t^^-> are the optical depth and the average duration of microlensing events, respectively, while f (0 < f < 1) is a parameter depending on the unknown stellar luminosity function. The observed mean duration of EAGLE events also depends on the luminosity function and is 0.01〜0 0.4 times the usual duration of microlensing events, which corresponds to 1 〜 30 days. The follow-up observation using larger telescopes may enable us to determine the impact parameter and the true duration of the event. If f is determined by another independent method, we can also determine τ^<LMC>. Even if f is undetermined, the detection of EAGLE events are due to the dim main-sequence stars. Although for the SMC, the event rate is smaller by a factor of 〜 7, it is still a substantial number (〜 13 f (τ^<SMC> / 3×10^<-7>) (100 days / <t^^->) events/y).
理論物理学刊行会の論文
1998-06-25