Black holes growing faster than expected

Jan 16, 2013
Credit: Swinburne University of Technology

(Phys.org)—Astronomers from Swinburne University of Technology have discovered how supermassive black holes grow - and it's not what was expected.

For years, scientists had believed that , located at the centres of galaxies, increased their mass in step with the growth of their . However, new observations have revealed a dramatically different behaviour.

" have been growing much faster than we thought," Professor Alister Graham from Swinburne's Centre for and Supercomputing said.

Within galaxies, there is a competition of sorts for the available gas; for either the formation of or feeding the central black hole.

For more than a decade the leading models and theories have assigned a fixed fraction of the gas to each process, effectively preserving the ratio of black hole mass to galaxy mass. New research to be published in The reveals that this approach needs to be changed.

"We now know that each ten-fold increase of a galaxy's stellar mass is associated with a much larger 100-fold increase in its black hole mass," Professor Graham said. "This has widespread implications for our understanding of galaxy and black hole coevolution."

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The researchers have also found the opposite behaviour to exist among the tightly packed clusters of stars that are observed at the centres of smaller galaxies and in disk galaxies like our .

"The smaller the galaxy, the greater the fraction of stars in these dense, compact clusters," Swinburne researcher Dr Nicholas Scott said. "In the lower mass galaxies the star clusters, which can contain up to millions of stars, really dominate over the black holes."

Previously it was thought that the star clusters contained a constant 0.2 per cent of the galaxy mass.

The research also appears to have solved a long-standing mystery in astronomy. 'Intermediate mass' black holes with masses between that of a single star and one million stars have been remarkably elusive.

The new research predicts that numerous galaxies already known to harbour a black hole - albeit of a currently unknown mass - should contain these missing `intermediate mass' black holes.

"These may be big enough to be seen by the new generation of extremely large telescopes," Dr Scott said.

Professor Graham said these black holes were still capable of readily devouring any stars and their potential planets if they ventured too close.

"Black holes are effectively gravitational prisons and compactors, and this may have been the fate of many past solar systems," Professor Graham said. "Indeed, such a cosmic dance will contribute at some level to the transformation of nuclear into massive black holes."

The researchers combined observations from the Hubble Space Telescope, the European Very Large Telescope in Chile and the Keck Telescope in Hawaii to create the largest sample to date of galaxies with reliable star cluster and supermassive black hole mass measurements.

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mvg
2.7 / 5 (3) Jan 16, 2013
Question:
Though there are black holes of various MASSES--What determines the size of each black hole's event horizion?

Would mid-size and massive black holes have a similar size event horizion?
Q-Star
3.9 / 5 (19) Jan 16, 2013
Question:
Though there are black holes of various MASSES--What determines the size of each black hole's event horizion?

Would mid-size and massive black holes have a similar size event horizion?


The event horizon is the spherical boundary where the escape velocity equals light speed. It is entirely mass dependent. The greater the mass, the larger the spherical event horizon.
Parsec
5 / 5 (7) Jan 16, 2013
Question:
Though there are black holes of various MASSES--What determines the size of each black hole's event horizion?

Would mid-size and massive black holes have a similar size event horizion?


The formula for calculating the escape velocity of any object is

Ve = sqrt( 2GM/r ). Given that the escape velocity = C (the speed of light), G is the gravitational constant, M = mass of the black hole, and r = radius of the black hole, you can solve for r for any M, or in fact solve for M given any r.

Note that I am using newton's basic formulation and not Einstein's. Still it should give a good number if everything is static (non-rotating etc.).
yep
1.2 / 5 (21) Jan 16, 2013
This is a re-hashed comment for the haters that missed it the other day under the NuStar catches black holes (magenta disco balls)in a galaxy web.
The mistake of the astrophysicists is to attribute mass to a quantity of matter. In the powerful magnetic field of a plasmoid, charged particles are constrained. Like particle accelerators the apparent masses become enormous as they approach the speed of light. Gamma and x-rays are coming out of our galactic center with energies in the tens of trillions of electron volts as that plasmoid is not a black hole, but the galactic nucleus of an intergalactic circuit.
obama_socks
1.3 / 5 (18) Jan 17, 2013
It's scary to think that some day the Earth and our whole solar system may be swallowed by a black hole. Pity those who may still be alive if that is about to happen and they know where they will wind up...even if it seems far off.
lengould100
4.7 / 5 (12) Jan 17, 2013
Weird comments.
Mike_Massen
1 / 5 (6) Jan 17, 2013
One wonders if, in respect of this article and black holes, the parallel of nuclei vs the electron shell has a similar pattern/relationship of mass ratio as one moves up the periodic table ?

ie. Although the mechanisms seem completely different in that the black hole mass is likely fully homogeneous but the nuclei in an atom is composed of discrete protons and neutrons (perhaps becoming homgeneous), would anyone care to map the graphs of galaxy ratio central black hole/overall mass to larger atoms nuclei/atom overall mass ?

Extrapolating this further, is there a point reached in respect of galaxy mass where a larger overall mass is not stable in a similar way to artificial high Z atoms are not stable or even cannot form in the first place ?
antialias_physorg
5 / 5 (6) Jan 17, 2013
parallel of nuclei vs the electron shell has a similar pattern/relationship of mass ratio as one moves up the periodic table ?

No. The article mentions a quadratic increase of black hole mass with galaxy mass (100 fold increase in black hole mass with 10 fold increase in galaxy mass)

For each proton you have one electron This relationship is 1:1 linear. (With proton/neutron mass being roughly 1000 times an electron mas. But that part is irrelevant for the increase in mass ratios between electrons and nucleons).

Larger atoms do tend to get increasingly larger amounts of neutrons but not nearly at a quadratic rate (Example: Element 10 has 10 neutrons; element 100 has 157 neutrons).

Only EM force acts with the square of the distance as gravity does. Weak and strong nuclear forces do not.
Tuxford
1 / 5 (20) Jan 17, 2013
Excellent. As I predicted, a survey correlating galaxy size to black hole size would support LaViolette's 'Continuous Creation' model where the core star is largely responsible for seeding the galaxy with new matter over long periods in a cyclic fashion.

http://phys.org/n...ter.html

http://phys.org/n...022.html

http://phys.org/n...ync.html

For those reluctant astronomers stuck with the relativist's fantasy, the core mother stars grow from within naturally. And denser regions grow more quickly. Thus, the prevalence of clusters in smaller galaxies with less dense overall regions; the clusters grow more quickly.

I am sorry you guys bet your careers on a math model. It is time to wake up. The longer you wait, the more embarrassed you will become.
barakn
4.5 / 5 (15) Jan 17, 2013

For those reluctant astronomers stuck with the relativist's fantasy, the core mother stars grow...

Yeah, because the spontaneous creation of matter/energy is so much easier to swallow. Not.
packrat
1.6 / 5 (14) Jan 17, 2013

For those reluctant astronomers stuck with the relativist's fantasy, the core mother stars grow...

Yeah, because the spontaneous creation of matter/energy is so much easier to swallow. Not.


Just out of curiosity, what is the difference between believing in that theory and believing in a big bang where the entire universe was created from a single point source? Neither one makes much sense to me from a practical physics aspect.
antialias_physorg
4.1 / 5 (18) Jan 17, 2013
Just out of curiosity, what is the difference between believing in that theory and believing in a big bang where the entire universe was created from a single point source?

Because one matches observation (CMBR) and the other does not?

Neither one makes much sense to me from a practical physics aspect.

Then maybe you should start to learn some practical physics?
Modernmystic
2.9 / 5 (15) Jan 17, 2013

For those reluctant astronomers stuck with the relativist's fantasy, the core mother stars grow...

Yeah, because the spontaneous creation of matter/energy is so much easier to swallow. Not.


Just out of curiosity, what is the difference between believing in that theory and believing in a big bang where the entire universe was created from a single point source? Neither one makes much sense to me from a practical physics aspect.


Since the universe is expanding now, what happens if you reverse this behavior into the past? Have you ever hit rewind on a movie? does it go back to the beginning if you let it roll long enough?

What would happen if you hit rewind on an expanding system as far as you could? Making any more sense from a practical physics aspect?
Mike_Massen
1.6 / 5 (7) Jan 17, 2013
No. The article mentions a quadratic increase of black hole mass with galaxy mass (100 fold increase in black hole mass with 10 fold increase in galaxy mass)
Thankyou for your forthright and considered response antialias_physorg and thankyou for going to the trouble and not being as lazy as me on this particular subject at this particular time ;-)

Interesting though that the curves go in the same general direction ie Similar trends, what significance do you think the relative differential has in terms of pointers to the relationship between the micro and macro and especially so in comparative log relationships ?

antialias_physorg
not rated yet Jan 17, 2013
what significance do you think the relative differential has in terms of pointers to the relationship between the micro and macro and especially so in comparative log relationships ?

None at all.

We're dealing with different forces (and force mixes) here. ALL force curves go in a similar direction, so no real 'relationship' there.
Infinum
1 / 5 (5) Jan 17, 2013
Event horizon of an object is the smallest possible surface area that contains maximum entropy of a quantum state.
packrat
1.6 / 5 (13) Jan 17, 2013
#1 Scientists don't really know what CMBR actually is. They have nothing more than a theory that has somehow become a 'fact' with nothing to back it up. There is still no way to prove what CMBR really is other than radio static from space that interferes with a few frequencies we use in terrestrial radio bands. Nobody knows where it really comes from.


#2 Practical physics says you don't get something from nothing! Give me an example where that isn't true in proven known science and not just another theory you happen to believe in.

Unless it can be proved it is nothing but another theory and theories are often wrong no matter how many people just happen to believe in them. People used to think the world was flat too.
Q-Star
3.3 / 5 (14) Jan 17, 2013
#1 Scientists don't really know what CMBR actually is. Nobody knows where it really comes from.


It's very well known that it comes from everywhere, from any point in space that you look, no holes, no gaps only slight (on the order of a few parts per 100,000 across any very small arc) fluctuations.


#2 Practical physics says you don't get something from nothing!


That is a true thing ya say. The CMB doesn't come from nothing, what's your theory? Remember, it has to be a source which is constrained by #1 above.

Unless it can be proved it is nothing but another theory


No theory can be "proved" to be true. But any theory must be falsifiable by observation & experimentation.

The statement: "nothing but another theory" is founded on a false premise. All theories are not equal. Some explain more phenomena than others. Some can't pass the test of observation. Some are supported better by the observations than others.

The good ones require work to understand.
Q-Star
3.2 / 5 (11) Jan 17, 2013
Good grief,,,, I just looked at your profile. And I am truly amazed that someone who calls himself a "retired engineer" would say something as inane as:

Unless it can be proved it is nothing but another theory,,,,


That is the sort of profound pronouncement you would expect from a Creationist, not a physicist. You don't talk like a "retired engineer",,,,,,
packrat
1.7 / 5 (12) Jan 17, 2013
Not really, It's what I see on here all the time. People saying if you can prove it then it is just a theory. People say the same thing to both people that come up with idea that can't be proven whether it's science or some type of religion as far as I can tell. I don't see why it would be wrong to put scientist in the same boat when their theory can't be proved.
Your right, it seems to come from everywhere in space but why can't it just be light that has been downshifted through distance just as easily as a big bang or whatever other ideas people come up with? I'm not saying there wasn't one, there very well could have been just that we can't prove it just by the radio waves we happen to be able to pick up. That's all.
Q-Star
2.8 / 5 (11) Jan 17, 2013
but why can't it just be light that has been downshifted through distance just as easily as a big bang or whatever other ideas people come up with?


Because that is exactly what it is, light that has been redshifted all the way down into the microwave range of the spectrum. But it doesn't come from point sources, it comes from every area of space regardless of where you look.

I'm not saying there wasn't one, there very well could have been just that we can't prove it just by the radio waves we happen to be able to pick up. That's all.


It's just a tad more than "radio waves we happen to pick up". The expansion over the history we observe. Run it backwards, where do you end up? The orderly evolution that can be observed by looking further and further back in time.

Big bang is an unfortunate term. "Cold inflationary expanding universe" would be better, IMHO. The standard model with inflation is the model that fits all the observations best. But no model is perfect.
antialias_physorg
not rated yet Jan 18, 2013
And I am truly amazed that someone who calls himself a "retired engineer" would say something as inane as:

He's probably a social engineer. No way he's ever had anything to do with real engineering.
Q-Star
2.5 / 5 (8) Jan 18, 2013
In dense aether model the large galaxies don't grow with accretion (outside-in) but with evaporation of matter from black hole-like artifacts: dense clouds of dark matter, so that the implications of the whole observations are reversed (inside-out model).


How do you read that, from this,,,, (From YOUR link.)

"How can the mass of a black hole grow faster than the stellar mass of its host galaxy? The study's authors suggest that a large concentration of gas spinning slowly in the galactic center is what the black hole consumes very early in its history. It grows quickly, and as it grows, the amount of gas it can accrete, or swallow, increases along with the energy output from the accretion. Once the black hole reaches a critical mass, outbursts powered by the continued consumption of gas prevent cooling and limits the production of new stars."
Tuxford
1.3 / 5 (13) Jan 18, 2013
"For years, scientists had believed that supermassive black holes, located at the centres of galaxies, increased their mass in step with the growth of their host galaxy."

Ah yes, scientific belief....right up there with religion. Let us have faith in the Huge Bang Fantasy!

And let's not forget which came first, the chicken or the egg. For years it has been known that the egg was first. Still they believe it was the chicken!

http://phys.org/n...tml#nRlv

Q-Star
2.8 / 5 (9) Jan 18, 2013
And let's not forget which came first, the chicken or the egg. For years it has been known that the egg was first. Still they believe it was the chicken!


Actually, it depends on which particular egg, and which particular chicken. The 1st chicken come FROM an egg, so the egg became before the 1st chicken. But all subsequent chickens came from eggs which were preceded (laid) by a chicken.

What's my point ya might be wanting to ask? Well since I know ya want to know, I'll tell ya. Ya can't base a theory of the entire universe from one unusual observation. The odd one or two galaxies don't tell ya much about the other 200 billion galaxies.

It would be like basing a theory of human evolution on observations of only club-footed midgets with red hair.
radek
1.7 / 5 (6) Jan 18, 2013
BH are still the biggest mystery in cosmology. We know that even in very early Universe there were SMBH (but we don`t know how they had been created). They grow much faster then we thought. How big they are now after billions of years? And why we don`t "see" such objects in near Universe?
Shelgeyr
1 / 5 (9) Jan 18, 2013
The mistake of the astrophysicists is to attribute mass to a quantity of matter. In the powerful magnetic field of a plasmoid, charged particles are constrained. Like particle accelerators the apparent masses become enormous as they approach the speed of light. Gamma and x-rays are coming out of our galactic center with energies in the tens of trillions of electron volts as that plasmoid is not a black hole, but the galactic nucleus of an intergalactic circuit.

True that! Far more likely a resonant circuit in energized plasma than a "black hole" (for which we have no evidence).
antialias_physorg
5 / 5 (3) Jan 19, 2013
Like particle accelerators the apparent masses become enormous as they approach the speed of light.

Not that enormous (and the amount of matter in the jet at anyo one time is miniscule compared to the object itself and the accretion disc.

Please do some very basic rough estimates before posting such nonsense.
katesisco
1 / 5 (9) Jan 19, 2013
I wish there was a settled opinion as to what, how & why of black holes. I myself, believe that red shifts are time distortions wrapped energy that obviates gravity.
Marco........Polo...........Marco..........Polo.
Torbjorn_Larsson_OM
5 / 5 (4) Jan 19, 2013
This is a contentious area, but it _would_ be nice if these results will bear up.

"parallel of nuclei vs the electron shell has a similar pattern/relationship".

Another breakdown besides mass is size, as shell sizes do not increase linearly with electron number. Transition metals are nearly the same size, because energy considerations makes them fill inner, previously empty, shells.

"support LaViolette's 'Continuous Creation' model". You can't support something that has been rejected by observation already. Or the existence of fantasy films would 'support' unicorns.

@packrat: The inflationary standard cosmology universe is zero energy. Such a universe can only form spontaneously btw.
Torbjorn_Larsson_OM
5 / 5 (5) Jan 19, 2013
"aether". Aether was rejected by observation over a century ago. We no longer think flat Earth is a viable idea either...

"the Huge Bang Fantasy". Which today has been tested to more than 5 sigma, including inflation separately, in the WMAP 9 year data release late 2012.

It is a well tested theory, it is the first self-consistent cosmology, it is an observation unlikely to be replaced. Improved, certainly.

@radek: SMBHs is usually, but not always, associated with the galactic center. We know Milky Way center has one, and it is thought to be the nearest.
Kron
1.6 / 5 (7) Jan 19, 2013
The CMBR and the Big Bang hypothesis are not mutually exclusive. The CMBR is not proof of a Big Bang. In addition, the red-shift of distant stars is not proof of an expanding universe.

Kicking and screaming does not change facts, physical models are not physical nature. Supporting evidence is not proof.

The CMBR proves the Big Bang Model is a possibility, it does not, however, prove the Big Bang was an actual event.

The Big Bang model will, and should, remain the mainstream cosmological model until it is proven as an impossibility. In other words, when physical evidence of nature that is not reconcilable with the model emerges, the Big Bang theory will be discarded.

So, if you want to replace a mainstream theory, you must first understand it, then prove why it doesn't work by specifically showing where and how it fails.
radek
1 / 5 (5) Jan 19, 2013


@radek: SMBHs is usually, but not always, associated with the galactic center. We know Milky Way center has one, and it is thought to be the nearest.


It is SMBH now. But few billions years earlier it wasn`t so big (if the pace of acretion remains the same). But I thought about such objects: http://phys.org/n...vey.html
SteveL
5 / 5 (1) Jan 20, 2013
Does a star's surface cool as its outer layers are being pulled off by a black hole?
Would a star swell as its internal gravity is lessened by loss of mass at a rate faster than the internal cooling?

Would stars be expected to often explode due to rapid changes including the reduction in external pressure due to loss of mass and the increase in internal heat by tidal forces, frictional turbulence and electromagnetic warping of its final stage?
Q-Star
2.8 / 5 (9) Jan 20, 2013
Does a star's surface cool as its outer layers are being pulled off by a black hole?


No, a star's thermal energy is greater at the core, not on the surface.

Would a star swell as its internal gravity is lessened by loss of mass at a rate faster than the internal cooling?


No, stars swell when the internal thermal pressure overcomes the inward pull of gravity. Like when shell hydrogen fusion and helium core fusion begins, or heavier elements. Think giants & super-giants.

Would stars be expected to often explode due to rapid changes including the reduction in external pressure due to loss of mass and the increase in internal heat by tidal forces, frictional turbulence and electromagnetic warping of its final stage?


Stars explode due to gravity mediated collapse in the absence of a counter balancing outward acting thermal pressure. In other words, they ran out of fuel, then they can no longer maintain a hydrostatic balance between thermal pressure and gra
antialias_physorg
not rated yet Jan 20, 2013
Would a star swell as its internal gravity is lessened by loss of mass at a rate faster than the internal cooling?

It wouldn't swell. It would get a lit cooler though. The mass of the star affects the rate of fusion. With loss of mass it would get smaller (i.e. less gravity to push stuff together and fuse atoms)

Smaller stars are generally cooler than larger ones (as long as we're in the hydrogen burning phase. When we shift over to helium, etc. then things change a bit - but that's only towards the end of a star's lifetime). So if the matter transfer is rapid enough and the star falls in slowly enough then it might even go out before reachingthe black hole.

Would stars be expected to often explode

As Q-Star notes: Stars don't explode. They IMPLODE when there's nothing left to burn (which creates photon pressure to counterbalance the crushing gravity) .

Strong gravity gradients can rip stars apart, though. But that wouldn't manifest as an explosion.
ValeriaT
1 / 5 (5) Jan 20, 2013
obama_socks
1 / 5 (6) Jan 21, 2013
Going out on a limb with this hypothesis and with nothing to back it up, presently...at least not until black holes are actually observed visually with future technology.

OK...what if Black Holes are "alive" as in a "Living organism"? (At this point, everyone guffaws.)
1) They attract and consume all types of matter that move in too closely; 2) they emit x-rays as "waste"; 3) they allegedly "grow" as they consume more matter and gases; 4) most forms of energies are unable to escape and are "digested"; 5) they presumably exist in space passively until their "food" is "detected" and is pulled toward them.
Consider a drop or two of seawater that is scanned under a microscope. You can see one-celled life floating in that water, consuming and being consumed and producing waste; and reproducing by halving or splitting in two. What we see microscopically might also be found on largerscale in the center of galaxies.

Perhaps Black Holes are the garbage disposals of the universe.

Just saying
antialias_physorg
4.2 / 5 (5) Jan 21, 2013
OK...what if Black Holes are "alive"

OK, you have been over the insanity horizon for quite some time. but now you've started accelerating again.
Silverhill
5 / 5 (3) Jan 21, 2013
@yep
The mistake of the astrophysicists is to attribute mass to a quantity of matter.
"Matter is generally considered to be a substance (often a particle) that has rest mass and (usually) also volume."

"In physics, mass, more specifically inertial mass, is a quantitative measure of an object's resistance to acceleration. In addition to this, gravitational mass is a measure of magnitude of the gravitational force which is:
1.exerted by an object (active gravitational mass), or
2.experienced by an object (passive gravitational force)
when interacting with a second object."

As you see, mass is part of the *definition* of matter, so to attribute mass to matter is a necessity, not a mistake.
When Cavendish was (indirectly) measuring the mass of Earth, he was definitely not confusing gravitational and electric effects: his test spheres were balls of simple lead, not plasma.
yash17
1 / 5 (5) Jan 22, 2013
"Within galaxies, there is a competition of sorts for the available gas; for either the formation of new stars or feeding the central black hole."

"BBT" gets puzzle with this.
"Carm" likes this.
gromm1t2
5 / 5 (1) Jan 22, 2013
"He's probably a social engineer. No way he's a real engineer."
Doesn't this site have Enuff trouble with comments from the peanut gallery? A war about some animals are more equal than other animals doesn't advance the level of commentary.why not address his argument, it's more subtle than ad hominen attacks.
Jon
A_Paradox
5 / 5 (1) Jan 22, 2013
I am curious as to how much of the dark matter around a galaxy falls into the central black hole?

Am I correct to assume that, if dark matter particles don't interact with each other nor with normal matter, they will therefore not form an accretion disk? This should mean their chances of entering the event horizon are considerably less than for ordinary matter, I mean unless they actually pass through the event horizon they will just keep going past the BH and loop back out in an elliptical path not correlated with either the ordinary matter accretion disk or the polar jets.
Silverhill
5 / 5 (1) Jan 22, 2013
Dark matter particles (aasuming their reality) do interact, with each other and with normal matter, if only gravitationally.
SteveL
not rated yet Jan 27, 2013
@ Q-Star and antialias; Thank you for your responses.
Fleetfoot
not rated yet Jan 29, 2013
I am curious as to how much of the dark matter around a galaxy falls into the central black hole?

Am I correct to assume that, if dark matter particles don't interact with each other nor with normal matter, they will therefore not form an accretion disk?


Assuming the collection has a low angular momentum, that is correct.

This should mean their chances of entering the event horizon are considerably less than for ordinary matter, I mean unless they actually pass through the event horizon they will just keep going past the BH and loop back out in an elliptical path not correlated with either the ordinary matter accretion disk or the polar jets.


Right, though they need to stay a little farther out, they spiral in if they get closer than 3/2 times the Schwarzschild radius.
A_Paradox
not rated yet Feb 01, 2013

This should mean their chances of entering the event horizon are considerably less than for ordinary matter, I mean unless they actually pass through the event horizon they will just keep going past the BH and loop back out ..


Right, though they need to stay a little farther out, they spiral in if they get closer than 3/2 times the Schwarzschild radius.


Why is that? [In plain English?]
I looked at Wikipedia and came to this sentence:
"This final equation indicates that an object orbiting at the speed of light would have an orbital radius of 1.5 times the Schwarzschild radius. This is a special orbit known as the photon sphere."

This seems contradictory to me; I thought the Schw. radius itself was the critical radius? I thought that a non interacting dark matter particle, barring accidents, would whiz past a black hole because its gravitational acceleration on approach [from approximately infinity] would give it energy/momentum enough for its retreat.
Fleetfoot
not rated yet Feb 01, 2013
.. they need to stay a little farther out, they spiral in if they get closer than 3/2 times the Schwarzschild radius.


Why is that? [In plain English?]
I looked at Wikipedia and came to this sentence:
"This final equation indicates that an object orbiting at the speed of light would have an orbital radius of 1.5 times the Schwarzschild radius. This is a special orbit known as the photon sphere."

This seems contradictory to me; I thought the Schw. radius itself was the critical radius?


The Schwarzschild Radius locates the event horizon. A free-falling particle with no tangential velocity reaches the speed of light at that radius, hence thereafter no light can reach us from it.

The 'photon sphere' on the other hand is where the transverse speed needs to be the speed of light to keep the object in a circular orbit. Any closer and gravity wins, but the object could return if it had an engine on board. (Not so from beyond the event horizon.)
Tuxford
1 / 5 (6) Feb 13, 2013
http://www.huffin...945.html

What? Supermassive Black Holes don't grow principally from mergers??? Say it ain't so! Two days later, and Physorg hasn't posted a thing on this embarrassing news!

Mark me down....but I have been consistent from the outset.