Letter to the Editor
The MEMO project: Combining all microlensing surveys to search for intermediate-mass Galactic black holes
Laboratoire de l’Accélérateur Linéaire IN2P3-CNRS, Université de Paris-Sud, BP 34, 91898 Orsay Cedex, France
Accepted: 8 September 2018
Aims. The microlensing surveys MACHO, EROS, MOA and OGLE (hereafter called MEMO) have searched for microlensing toward the Large Magellanic Cloud for a cumulated duration of 27 years. We study the potential of joining these databases to search for very massive objects, that produce microlensing events with a duration of several years.
Methods. We identified the overlaps between the different catalogs and compiled their time coverage to identify common regions where a joint microlensing detection algorithm can operate. We extrapolated a conservative global microlensing detection efficiency based on simple hypotheses, and estimated detection rates for multi-year duration events.
Results. Compared with the individual survey searches, we show that a combined search for long timescale microlensing should detect about ten more events caused by 100 M⊙ black holes if these objects have a major contribution to the Milky Way halo.
Conclusions. Assuming that a common analysis is feasible, meaning that the difficulties that arise from using different passbands can be overcome, we show that the sensitivity of such an analysis might enable us to quantify the Galactic black hole component.
Key words: gravitational lensing: micro / surveys / Galaxy: halo / dark matter / Galaxy: kinematics and dynamics / stars: black holes
© ESO 2018
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.