New LIGO Events Demolish The Idea Of A ‘Mass Gap’ Between Neutron Stars And Black Holes
“For decades, we knew only of neutron stars that existed below about twice the Sun’s mass, and black holes that existed at or above about five times the Sun’s mass. Beginning in 2017, we started to see neutron stars merging together to form black holes that fell into that empty range, but those events were relatively infrequent. However, this latest discovery — of two low-mass black holes merging together to form a heavier black hole — should close off the “mass gap” range for good.
What was once a region of unknowns should now be filled in by black holes. Although there’s still a lot of science left to do to determine how rare or common black holes of different masses are, particularly in the realm of population statistics, it would now be very surprising if there were a gap in masses between neutron stars and black holes. LIGO’s latest data has demolished that idea. Despite cries of, “NOT NOW LIGO,” the Universe continues to send data our way, and our scientific discoveries go on.”
For decades, we’ve known that supernovae make both neutron stars and black holes. But until LIGO started detecting gravitational waves, we’d never seen a neutron star over 2 solar masses, and we’d never seen a black hole of less than 5 solar masses. Although LIGO saw two neutron stars merge to form a black hole a couple of times, leading to a black hole in that “mass gap” range in both instances, it had never seen two “mass gap” black holes merging before.
Well, we’re almost a year into LIGO’s third (and upgraded) data run, and already it’s seen four, including a new one this past Monday. The mass gap should be gone, and LIGO’s the observatory that demolished it.