I may be wrong, but I suspect that any nearby black holes (i.e. within a few dozen light-years) with active accretion disks would already be visible to us in visible light and would also be bright enough in x-ray emissions that prior searches would have uncovered them.
In my limited googling, the smallest active black hole I could find was A0620-00A, which is about 6 solar masses. Its accretion disk is visible in x-rays from 3000 light-years away, so I assume any small black holes accreting matter anywhere near us would also be visible.
So more sensitive x-ray instruments would be useful for finding more distant SMBHs, but not necessary for finding any small, nearby black holes that we could actually stand a chance of reaching with a spacecraft. Most likely there just aren’t any active black holes in our neighborhood — only quiet ones we can’t see in x-rays.
Yeah. I thought small accretion disks might persist… But probably not.
Outside of invisible binary partners (which higher resolution “wobble” detectors could catch), it’s hard to imagine detecting quiet black holes. Even theoretically… like even radiation or particles they perturb would be impossibly faint from so far.
I may be wrong, but I suspect that any nearby black holes (i.e. within a few dozen light-years) with active accretion disks would already be visible to us in visible light and would also be bright enough in x-ray emissions that prior searches would have uncovered them.
In my limited googling, the smallest active black hole I could find was A0620-00A, which is about 6 solar masses. Its accretion disk is visible in x-rays from 3000 light-years away, so I assume any small black holes accreting matter anywhere near us would also be visible.
So more sensitive x-ray instruments would be useful for finding more distant SMBHs, but not necessary for finding any small, nearby black holes that we could actually stand a chance of reaching with a spacecraft. Most likely there just aren’t any active black holes in our neighborhood — only quiet ones we can’t see in x-rays.
Yeah. I thought small accretion disks might persist… But probably not.
Outside of invisible binary partners (which higher resolution “wobble” detectors could catch), it’s hard to imagine detecting quiet black holes. Even theoretically… like even radiation or particles they perturb would be impossibly faint from so far.