You ask very good questions. > Wouldn’t these black holes radiate some Hawking radiation, making them potentially detectable? Yes, according to widely accepte

You ask very good questions. > Wouldn’t these black holes radiate some Hawking radiation, making them potentially detectable? Yes, according to widely accepted theory, they do. However, Hawking radiation is incredibly weak. With current technology, we are not able to detect such a faint signal. > And how long would they exist for? This depends on the size of the black hole. They will last much longer than our solar system, many billions of years, until they eventually evaporate. > Also, what keeps these black holes from interacting with normal matter and clumping in the center of galaxies? They do interact with normal matter via gravitation. If primordial black holes exist, many of them would fall into the supermassive black hole at the center of our galaxy and other galaxies. However, there are also those that orbit around the center. The problem is that our telescopes currently cannot detect a tennis ball-sized black object with the mass of a few Earths, it is an incredible tiny black dot in front of a black background. Hence, they are literally dark matter.