Final answer:
MACHOs, considered as potential dark matter candidates, include black holes, brown dwarfs, and white dwarfs. Red dwarfs and primordial black holes are also speculated, but insufficient evidence exists to account for all the dark matter in the Milky Way's halo.
Step-by-step explanation:
The types of MACHOs (Massive Compact Halo Objects) that would be found in the halo of the galaxy are candidates for dark matter.
They include objects such as black holes, brown dwarfs, and white dwarfs.
In the search for dark matter, researchers consider MACHOs because these objects can gravitationally lens the light from distant stars, causing a characteristic brightening known as microlensing.
Although some MACHOs have been detected through this technique, they do not account for all of the dark matter in the halo of the Milky Way.
Red dwarfs, which are dim, small stars, along with white dwarfs, are also considered potential MACHOs.
White dwarfs can have about a solar mass and are roughly the size of Earth but might dim to the extent that they become difficult to observe.
Some theories also suggest the existence of primordial black holes formed during the Big Bang as potential MACHOs, but there is no concrete evidence for this yet.