A strange LIGO signal could reveal the missing link behind dark matter

Primordial black holes have remained one of astronomy's most intriguing ideas for decades. Now, researchers at the University of Miami believe a recent gravitational wave detection may bring scientists closer to confirming that these ancient objects are real, a breakthrough that could also help solve the enduring mystery of dark matter.

Primordial black holes have remained one of astronomy's most intriguing ideas for decades. Now, researchers at the University of Miami believe a recent gravitational wave detection may bring scientists closer to confirming that these ancient objects are real, a breakthrough that could also help solve the enduring mystery of dark matter.

Primordial black holes are thought to have formed during the first fraction of a second after the Big Bang, long before the first stars or galaxies existed. Unlike the black holes created by collapsing stars, these hypothetical objects could range in size from something as small as an asteroid to much larger bodies.

Although no primordial black hole has ever been confirmed, scientists believe they could answer several major questions about the universe. One of the biggest is the nature of dark matter, the invisible substance that makes up about 85 percent of all matter and provides the gravitational pull that helps hold galaxies together.

"We believe our study will aid in confirming that they actually do exist," said Nico Cappelluti, an associate professor in the University of Miami's Department of Physics, referring to research he conducted with Ph.D. student Alberto Magaraggia.

Their work builds on a possible discovery reported by the Laser Interferometer Gravitational-Wave Observatory (LIGO), which late last year detected an unusual gravitational wave signal. Gravitational waves are ripples in spacetime produced by some of the universe's most violent events, including collisions between black holes.

Most known black holes form after massive stars explode as supernovas. Their masses typically range from several times the mass of the Sun to billions of solar masses.

"The most common black holes form as the result of a supernova, the death of a massive star. So, their masses can range from a few times the Sun's mass to billions of solar masses," Cappelluti explained.

But in November, LIGO issued an automated alert for a merger in which at least one object appeared to have less than one solar mass. Such a small black hole would be difficult to explain through conventional stellar evolution and instead could point to a primordial black hole.