Where Are All the Tiny Black Holes?
Are small black holes just hard to find, or might they not exist at all? “It’s important to establish observationally whether this gap is real, or whether it’s an observational artifact,” says Vicky Kalogera, an astrophysicist at Northwestern University and a leading member of the LIGO team. Recent discoveries are starting to suggest the latter might be the case. In the past two years, researchers have found several possible black holes in the mass gap. Then, earlier this month, astronomers presented evidence of what might be the best candidate yet: an object of 2.9 solar masses dubbed “the unicorn.”