To put it simply, Dark Matter remains one of the most elusive and troublesome mysteries facing astronomers today. Despite the fact that it comprises 84.5% of the matter in the Universe, all attempts to discover it have so far failed. Many candidates have been proposed, ranging from ultralight particles (axions) to Weakly-Interacting Massive Particles (WIMPS) and Massive Compact Halo Objects (MACHOs).

However, these candidates range in mass by an order of 90, which several theorists have tried to resolve by proposing that there could be multiple types of dark matter. However, this would require different explanations for their origins, which would only complicate cosmological models further. As Miguel Zumalacárregui explained in a recent UC Berkeley press release:

“I can imagine it being two types of black holes, very heavy and very light ones, or black holes and new particles. But in that case one of the components is orders of magnitude heavier than the other, and they need to be produced in comparable abundance. We would be going from something astrophysical to something that is truly microscopic, perhaps even the lightest thing in the universe, and that would be very difficult to explain.”

For the sake of their study, the team conducted a statistical analysis of 740 of the brightest supernovas discovered (as of 2014) in order to determine if any of them had been magnified or brightened by a the presence of an intervening black hole. This phenomena, where the gravitational force of a large object magnifies the light coming from more distant objects is known as “gravitational lensing“.

Basically, if black holes were the dominant form of matter in the Universe, then gravitationally-magnified supernovas would occur rather frequently because of primordial black holes. These hypothetical forms of black hole are believed to have formed within the first few milliseconds after the Big Bang in parts of the Universe where mass was concentrated at tens or hundreds of Solar Masses, causing the earliest black holes to form.