From: Henry Baker <hbaker1@pipeline.com> Schwarzschild radius ~ 1000 AU ~ 139 light-hours ~ 5.8 light-days ~ 1 light-week.
So, this black hole is bigger than our solar system almost out to the Oort cloud.
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/blkhol.html
http://arxiv.org/pdf/1511.08502v2.pdf
How Big Can a Black Hole Grow?
Andrew King
Department of Physics & Astronomy, University of Leicester, Leicester LE1 7RH UK
Astronomical Institute Anton Pannekoek, University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam, The Netherlands
10 December 2015
ABSTRACT
I show that there is a physical limit to the mass of a black hole, above which it cannot grow through luminous accretion of gas, and so cannot appear as a quasar or active galactic nucleus. The limit is Mmax ~ 5*10^10 Msun for typical parameters, but can reach Mmax ~ 2.7*10^11 Msun in extreme cases (e.g. maximal prograde spin). The largest black hole masses so far found are close to but below the limit. The Eddington luminosity ~ 6.5 * 10^48 ergs^-1 corresponding to Mmax is remarkably close to the largest AGN bolometric luminosity so far observed.
--his title is very deceptive. His claim is, if a black hole were too big, then any infalling "accretion disk" pattern of gas, would not be "luminous" which would tend both to make the black hole invisible, and would tend to slow down its rate of growth. The reason is any accretion disk would become unstable and break up, so the black hole could not grow steadily in an accretion-disk style. But: that in no way stops a black hole from being heavier than King's so-called upper limit, and it also in no way stops a heavier hole from being detected. It could grow by nonluminous accretion such as swallowing stars, and such a swallow by the way would be observable. This growth mechanism might be slow, but is not zero. Also, it could be detected by its gravitational effects. http://www.space.com/28664-monster-black-hole-largest-brightest-ever.html claims the largest known hole is 1.2*10^10 solar masses, not too far below King's upper limit. I think this whole claim by King is important in the sense it helpfully prevents black holes from growing too big and swallowing whole galaxy... or at least that would take much longer than the current age of the universe. It thus helps explain why universe is the way it currently is. QUESTION: Express King's mass upper limit in terms of fundamental physical constants. (He didn't, but it ought to be possible.)