Review of results from EROS Microlensing search for Massive Compact Objects

TL;DR

This paper reviews the EROS2 microlensing survey results, which monitored 67 million stars over seven years to search for dark matter in the form of MACHOs, finding limited evidence for such objects in the galactic halo.

Contribution

It provides comprehensive observational constraints on MACHOs as dark matter candidates, ruling out their significant contribution in the specified mass range.

Findings

Only one microlensing event towards Magellanic stars was observed.

Massive compact halo objects in the mass range $10^{-7}M_igodot$ to $5M_igodot$ are excluded as major halo components.

Hundreds of microlensing candidates found in the galactic plane, but not towards Magellanic clouds.

Abstract

We present the results of the EROS2 search for the hidden galactic matter of the halo through the gravitational microlensing of stars in the Magellanic clouds. Microlensing was also searched for and found in the Milky-Way plane, where foreground faint stars are expected to lens background stars. A total of 67 million of stars were monitored over a period of about 7 years. Hundreds of microlensing candidates have been found in the galactic plane, but only one was found towards the subsample of bright --well measured-- Magellanic stars. This result implies that massive compact halo objects (machos) in the mass range $10^{-7}M_\odot<M<5M_{\odot}$ are ruled out as a major component of the Milky Way Halo.