alone black holes

[taylordnz]

are there any black holes found that have no companion stars or anything with them, are there any found?

if so could you please name a few on this thread

thanks

[Nereid]

Originally posted by taylordnz
are there any black holes found that have no companion stars or anything with them, are there any found?

if so could you please name a few on this thread

thanks If they were truly isolated, it's hard to imagine how they'd be detected, other than by gravitational lensing.

The one that best meets your criterion is the supermassive one at the centre of our Milky Way galaxy - we know it's there, how massive it is, etc, yet there are no accretion disks, jets, etc. Of course, if by 'companion stars' you mean stars orbiting about a BH, then we're such a companion (although there's an awful lot more mass than just the galactic BH which contributes to our motion).

This link gives you an idea of how 'alone' the Milky Way centre BH is:
http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html

[Phobos]

possible detection of a lone black hole...
http://antwrp.gsfc.nasa.gov/apod/ap000119.html

[Jess]

Originally posted by Nereid
If they were truly isolated, it's hard to imagine how they'd be detected, other than by gravitational lensing.

The one that best meets your criterion is the supermassive one at the centre of our Milky Way galaxy - we know it's there, how massive it is, etc, yet there are no accretion disks, jets, etc. Of course, if by 'companion stars' you mean stars orbiting about a BH, then we're such a companion (although there's an awful lot more mass than just the galactic BH which contributes to our motion).

This link gives you an idea of how 'alone' the Milky Way centre BH is:
http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html

There is a radio source at Sgr A* though - thought to be very low level activity due to heated matter orbiting the BH.

Jess

[Physicsisfun2005]

Don't Black Holes emit X-rays???? I believe that is a way to detect them. IF a BH doesn't have anything around it to "feed" on i believe it decays at a certain rate (i swear i saw a BH decay equation for a static BH that doesn't gain mass from "feeding" on objects)

[chroot]

Yes, black holes "evaporate" via Hawking radiation. The actual power lost by the black hole is a function of its size (and thus its mass): small black holes evaporate very very quickly, while large ones evaporate only very slowly.

- Warren

[Nereid]

The Hawking radiation which stellar mass black holes emit, IIRC, is far less than what such a BH would emit just from absorption of stray ISM (inter-stellar medium) particles, and cosmic rays. For a giant BH like the one at the centre of the Milky Way, Hawking radiation would be undetectable, even from up close.

[Labguy]

Originally posted by Nereid
The Hawking radiation which stellar mass black holes emit, IIRC, is far less than what such a BH would emit just from absorption of stray ISM (inter-stellar medium) particles, and cosmic rays. For a giant BH like the one at the centre of the Milky Way, Hawking radiation would be undetectable, even from up close. Correctomundo. See: http://casa.colorado.edu/~ajsh/hawk.html and notice the middle of the page about the (lack of) energy from the 3 billion Ms in the giant elliptical galaxy M-87. Also, much more back awhile at:

http://www.physicsforums.com/showthread.php?s=&threadid=9878