Mystery black hole hides by curbing its appetite A well-known radio source has turned out not to be the galaxy it's been classified as for 20 years, but a surprisingly quiet black hole. The discovery is causing a bit of buzz among astrophysicists because it suggests there could be thousands or millions more “covert” black holes out there waiting to be discovered. It took …
I would assume no, as some scientists/mathematicians/astrophysicist etc have tried to accound for dark matter via naked black holes. Dark matter usually outstrips most assumptions, and as it seems to lie outside of galaxies, black holes don't seem to fit the bill.
That is, unless totally naked (no matter around them or gas), then we would see a faint glow around some galaxies as little jets of gas/stars/wondering rocks hit the black holes. We see none, hence it is "dark" matter, not "warmed and glowing with a snug jumper" matter. :)
http://www.forbes.com/sites/startswithabang/2016/05/26/black-holes-as-dark-matter-heres-why-the-idea-falls-apart/#3a4646246d7b
However the above article suggests some early black holes could account for some of the matter. The closer we get with each slice, the closer to knowing what is left that is truly "dark", but still existing (no, not magic, just invisible like radio waves or sub atomic particles :P ).
"That's a very unlikely possibility"
Indeed: That kind of recession would show up pretty damned quickly inside a galaxy. There's simply too much "stuff" around for a black hole to be able to zip through stealthily at a large fraction of the speed of light (it'd need to be 80%+ to get that kind of redshift)
Disclaimer: I most certainly do NOT lay claim to knowledge or credentials to make the text below a statement. I am trying to expand my own learning and therefore continue presenting it as questions.
"could be thousands or millions more 'covert' black holes out there waiting to be discovered."
I've asked this for several years: How do we know there aren't many more black holes that we simply can't see for one reason or another and THEY are, at least in part, the so-called "missing mass" of the universe? There may well be many black holes from the early universe that have since consumed everything around them (therefore not emitting x-ray death screams) and with not much behind them (from our perspective, therefore not giving away their position with gravitational lensing/distortion). I readily grant that it would take an AWFUL LOT of these to make up the required total mass to fit the models but, it would certainly lessen the need to rely on exotic theories. And this may also help to explain the uneven distribution of matter in the universe. Perhaps in some of the particularly empty regions sit one or more black holes that have digested everything within reach and sit quietly and darkly waiting for something else to eat.
The LIGO results have made us take that idea a lot more seriously. But the type of system described here is almost certainly a normal astrophysical system, because it's paired with an ordinary star and because the black hole is too light to be primordial. (We have observational evidence that primordial black holes can't be "light" -- IIRC, under 20-30 solar masses.)
There is a problem as there are ongoing search for microlensing effects due to black holes passing in front of other stars, and I have not heard that a massive population of hitherto invisible black holes is now suspected to exist.
Here's one example of someone doing some maths. It says a black hole population of 20-100 solar masses isnt ruled out by observation evidence.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
