...Primordial black holes (PBHs) are only hypothetical, but they generate a lot of interest. If they're real, they formed immediately after the Big Bang from direct collapse of dense clumps of subatomic matter, without the need for any stellar progenitor. Researchers have long thought that they could be the prime component, or even the only component, of dark matter...

This schematic shows a PBH passing through a white dwarf. As it passes through, its gravitational force creates tidal heating in the middle of the white dwarf. Once the material reaches the threshold temperature of <~0.5 billion Kelvin, it triggers uncontrolled nuclear burning. If the region burning is big enough, then thermonuclear runaway will trigger a Type Ia supernova. Image Credit: Kavli IPMU/Gemini AI (Banana Pro)...