Why don’t planet hunters find black holes?

[jimgraber]

Over 200 planets have been discovered by the radial velocity technique. Why no black holes? For similar periods, the signal amplitude should be much greater.
TIA.
Jim Graber

 

[cadnr]

I'm no expert in this area, but I believe that such systems (a star orbiting a black hole) would inevitably become what are known as "X-ray binaries", as matter is drawn from the star into a hot X-ray-emitting accretion disc around the black hole. The stellar spectral lines in such systems are indeed subject to enormous periodic Doppler shifts. I'm not sure how X-ray binaries are normally discovered though...

 

[ray b]

BHs are not nearly as common as planets
while they would really bounce a star's orbit
just looking for X-rays is a more common way to find them

V4641 Sgr is 1600 light years away at the closest found