Massive Astrophysical Compact Halo Objects These are candidates for the dark matter in galaxy halos, with masses in the range from brown dwarfs to white dwarfs With the possible exception of primordial black hole MACHOs, they would likely be baryonic dark matter Several experiments have been carried out and others are underway to detect MACHOs through their gravitational microlensing (amplification) of the light from background stars, first using the LMC as a background and more recently using Andromeda A number of microlensing events toward the LMC were detected, but their interpretation is uncertain As much as 30% of the dark matter in the Milky Way halo could be in the form of MACHOs
Dark matter jargon for Massive Compact Halo Objects referring to objects in galactic halos made of protons and neutrons; also called baryonic matter
Massive Compact Halo Objects Low-luminosity objects such as planets and brown dwarfs which contribute to the mass of the galactic halo