I would like to open this up for general discussion. Feel free to join in.
For years I've been reading articles about "Dark Matter" which is binding together galaxies that would fly apart from angular momentum if there was only the gravity of the visible matter to work with. There has been much argument over whether it is WIMPs, MACHOs, neutrinos, some fantastic yet unknown particles, etc. ad infinitum.
I have been reading just such an article in the September 2001 issue of Sky & Telescope (yes I'm that far behind). It got my feeble brain working and...I had an idea.
Stellar mass black holes (BH) are quite small in general. The event horizon would be only a few tens to hundreds of miles in diameter. Practically speaking no bigger than a good sized astroid. What if these BH are common rather than rare? What if there are tens or hundres of billions of four to ten solar mass BH with EH's of 100 miles diameter or less, in solitary orbit of the Milkyway? How would they manifest themselves?
I know gravitational lensing and stellar purturbations. But would these events be common enough to draw our attention? I would think that picking a 100 mile BH out of the background at 5,000 ly would be pretty tough, even if there were millions. Especially in the halo, I'd think they'd be so seperate and solitary that they'd disapear except in the rare event they passed infront of something.
Any of you Professional Astronomers/Scientists know anything about this? I'd love to hear your dissertations on the topic. Anybody?