Black holes with masses less than their heavyweight relatives – the standard and supermassive black holes – and weighing in at less than three solar masses are dubbed mini black holes, formed in the pressure of interstellar clouds. Because they are so small, they also have a little bit of difficulty when it comes to forming on their own. Low mass also means low gravity and this directly implies that these pint-sized objects cannot completely collapse in on themselves. In comparison, black holes of more than three times the Sun’s mass are made when a star reaches the end of its life and gets crushed under its own gravity. Other black holes of greater masses are hypothesised to have formed through the merging of smaller black holes.
In order to make a mini black hole there needs to be an enormous outside pressure to offer some assistance. The theory goes that during the dense turbulent past from which today’s universe emerged the enormous crushing pressures created many mini black holes. Unusually they are likely to have been incredibly heavy but quite tiny – possibly as small as a proton (the positive subatomic particle that can be found in atoms). According to quantum mechanics, it is thought that they spontaneously throw out energy before evaporating in a final violent explosion after billions of years in existence. They also may not be as black as heavier black holes.
We’ve yet to find some actual observational evidence that they exist but as it stands, there could be mini-black holes scattered throughout the Universe and close to our Solar System!
Image courtesy: NASA
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