Question R1 Q5 - NSB Double Elimination 2012

Why are massive compact halo objects (MACHOs) thought to be unable to completely explain the dark matter problem?

W) They would have evaporated by Hawking radiation in less than a Hubble time

X) Cosmic microwave background radiation observations indicate that MACHOs could not have formed in a Hubble time

Y) Several MACHOs would be detectable in the solar system but are not observed

Z) There should be a lot more MACHOs observed through microlensing

Science Bowl Question