Think about you’re a neutron star. You’re fortunately floating in area, too previous to fuse nuclei in your core anymore, however the quantum strain of your neutrons and quarks simply retains you from collapsing underneath your individual weight. You look ahead to a protracted stellar retirement of step by step cooling down. Then someday you might be struck by a tiny black gap. This black gap solely has the mass of an asteroid, but it surely causes you to develop into unstable. Gravity crushes you because the black gap consumes you from the within out. Earlier than you understand it, you’ve develop into a black gap.
In response to new analysis printed in Bodily Assessment Letters, this situation would possibly occur now and again, and it might clarify darkish matter and the smallest black gap we’ve noticed.
Neutron stars sometimes have a mass between 1.5 and a pair of photo voltaic plenty. They type as a result of the quantum strain of neutrons is robust sufficient to counter the gravitational weight of the star. However there’s a restrict to how a lot mass a neutron star can have. It’s referred to as the Tolman-Oppenheimer-Volkoff (TOV) limit. This restrict is difficult to calculate, however we expect it’s round 2.5 photo voltaic plenty. Something above the TOV restrict ought to collapse right into a black gap.
The biggest neutron star we’ve noticed is about 2.24 photo voltaic plenty. The smallest black gap we’ve noticed is about 2.6 photo voltaic plenty. On the one hand, this appears to substantiate that 2.5 photo voltaic plenty is a reasonably good estimate of the TOV restrict. Alternatively, this raises an fascinating query about how such a small black gap might have fashioned.
Many stellar-mass black holes type when a big star explodes as a supernova. Its core is compressed and gravitationally collapses. Primarily based on our understanding of enormous stars, the smallest stellar-mass black holes must be round four photo voltaic plenty. Black holes might additionally type when two neutron stars collide, or maybe the collision of a white dwarf and neutron star, however these also needs to produce black holes which can be at the least three photo voltaic plenty.
So how does a black gap of solely 2.6 photo voltaic plenty type? Whereas a merger can create small black holes, this new examine seems to be at an alternate. The thought entails primordial black holes. These hypothetical black holes may need fashioned within the early universe, and could have a mass smaller than Earth. If primordial black holes exist, then they might collide with a neutron star, inflicting it to break down right into a solar-mass black gap.
Whereas the thought has been proposed earlier than, on this examine the staff seems to be at how this would possibly connect with darkish matter. Some astronomers have proposed that darkish matter may very well be product of primordial black holes. If that’s true, the cosmos should be crammed with primordial black holes, and collisions with neutron stars must be widespread. So the staff appeared on the mass distribution of recognized neutron stars and calculated the probably dimension of photo voltaic mass black holes. It seems to be between 1 and a pair of.5 photo voltaic plenty. So the smallest black gap we’ve noticed may need been fashioned by means of a primordial black gap collision.
That is an fascinating concept, however present proof is hardly compelling. Nonetheless, as LIGO and Virgo observe extra black gap collisions, they could observe many extra small black holes. In the event that they do, we would have to have a look at this concept of darkish matter extra carefully.
Reference: Takhistov, Volodymyr, George M. Fuller, and Alexander Kusenko. “Test for the Origin of Solar Mass Black Holes.” Bodily Assessment Letters 126.7 (2021): 071101.