Largest Black Hole Measured

porkpickle tips us to a BBC article on the quasar OJ287, a binary object containing largest black hole yet discovered, weighing in at 18 billion times the mass of Sol. Researchers were able to estimate its mass due to the presence of a smaller black hole in orbit around it. When the smaller companion's orbit intersects OJ287's accretion disk, once every 12 years, it triggers a burst of radiation that was detected by the Spitzer Space Telescope. More detail and a diagram are available on the Turku University site.

eh? I don't get it?

[by Anonymous Coward]

How large can a singularity be?

I mean, if they used the word "massive" I'd get it. But large?

Re:eh? I don't get it?

[AmaDaden (794446)]

It think they are not 100% sure about the whole "a black hole is a singularity" thing.

quantum mechanics .... does not allow objects to have zero size--so quantum mechanics says the center of a black hole is not a singularity but just a very large mass compressed into the smallest possible volume.

from http://en.wikipedia.org/wiki/Black_hole [wikipedia.org]

Re:eh? I don't get it?

[BobGod8 (1123841)]

Actually it's way more complicated than that. Only non-rotating black holes could ever truly be point masses. Any angular momentum creates complicated tidal effects near the center, resulting in a non-point-mass. Carried further, the "singularity" expands until the point where it would effectively reach the event horizon itself, resulting in a naked singularity, which some calculations have shown can have actual size. Adding further rotation will (to a point), actually change the size of the "singularity". Of course, this is all moot, since that's not at all what the article was talking about, but that's my .02$.

Re:eh? I don't get it?

[by Anonymous Coward]

That's misleading, and I'm guessing you don't really understand what you're describing. A rotating black hole (aka every black hole, to some extent), is still a singularity (no need for quotation marks, it still has zero volume) despite not being a point. It's a ring with zero cross-sectional area, sort of like an infinitely thin thread arranged in a circle.

Furthermore, this thread is based on quibbling over semantics without really understanding what the author quite validly meant. The "black hole" aspect of a singularity is a description of the effects of its event horizon, which of course scales with mass. A more massive black hole is by definition larger then a less massive black hole. Someone mod this up so this misunderstanding can be cleared up for more people.

Re:eh? I don't get it?

[pclminion (145572)]

A black hole has an event horizon. This horizon has a very well-defined size.

500 AU event horizon

[peter303 (12292)]

BIG 2.7 km per solar mass.

correction: 325 AU

[peter303 (12292)]

used miles instead of km for AU :-)

Re:eh? I don't get it?

[moderatorrater (1095745)]

The event horizon is often considered the size of a black hole since nothing could ever leave that space.

Re:

[Ambitwistor (1041236)]

No. If you try to create gravitational waves (or light waves) and sent them back out through the horizon, they instead fall into the singularity (albeit more slowly than you yourself do as you fall, so you still see them traveling away from you).

Re:

[jgarra23 (1109651)]

How large can a singularity be?

I mean, if they used the word "massive" I'd get it. But large?

I believe they are measuring the event horizon, not the singularity.

Wow.

[AltGrendel (175092)]

A binary black hole system.

Proctologists across the globe swoon!

so is Rosie orbiting Oprah, or vice versa?

[ImYY4U (539546)]

Which one weighs 18 billion times our sun, and which ones weighs 100 million times our sun?

Ask slashdot

[sm62704 (957197)]

Is there a theoretical limit to the size of a black hole?

That was serious, here's the link [uncyclopedia.org] to the non-serious.

A Black hole is an impossible object which makes the Universe work. It has the useful property of being "undetectable". It's like when your spouse comes home with a dent in the car, and blames it on an invisible black mass; the dent is proof of the black mass, but you can't, and never will be able to see it with CCTV cameras, but you know it's there. "Dark matter" is an equally undetectable force that causes cars to defy gravity, and hit invisible black holes. Astronomers will tell you that lots of them have spouses with dents in their cars, and can explain this is very technical terms, so you won't be able to understand why it's not possible.

More there...

Re:Ask slashdot

[ArcherB (796902)]

Is there a theoretical limit to the size of a black hole?

While I can't give you numbers since I'm going from memory, but there used to be a theoretical limit to black hole size. This was before "Super Massive Black Holes" were discovered in the center of every galaxy. Super Massive Black Holes are much more massive than the previous theoretical limit and were thought to be impossible so many astronomers were claiming that such a thing was couldn't exist while others were saying, "Oh yeah? Then why don't you put down the chalk, professor, and come down to my observatory and tell me what that big-ass black gravity thing is in the middle of our galaxy!" (Of course, they couldn't really see it, but you get the point)

I think astronomers are reluctant to guess at a size limit now as they don't want another discovery to make them look like asses.

Re:

[Ambitwistor (1041236)]

While I can't give you numbers since I'm going from memory, but there used to be a theoretical limit to black hole size.

There has never been a theoretical limit to the size of a generic black hole. (Technically, the observable universe could be in a giant black hole.) But back when people thought the only way a black hole could form was from the collapse of a single star, there was a practical limit on the size of an astrophysical black hole: if it forms from stellar collapse, it can't be more massive than the most massive stars. Everyone recognized that black holes can get larger by swallowing more mass, but it was a l

Re:

[Cassini2 (956052)]

The Eddington limit [wikipedia.org] appears to limit the size of a star. At one point in time, it was thought that black holes formed from the collapse of stars. Later on, it was concluded that supermassive black holes are very good at feeding on neighboring stars, and thus supermassive black holes could form. The Wikipedia page on Black Hole Parameters [wikipedia.org] has an explanation.

When it comes to choosing neighbors,

[davidsyes (765062)]

I pine for Sol, not a massive black hole. Otherwise, we'll have a massive cleanup job? Oh, wait...

Re:

[geekoid (135745)]

ok, that was bad.
Not "hahaha man that was bad haha." just lame.

Ugh, the jokes aren't even funny anymore...

[AndGodSed (968378)]

Seems like /. is going down one of them two holes...

Need a better measurement comparison

[vjmurphy (190266)]

"largest black hole yet discovered, weighing in at 18 billion times the mass of Sol."

Yes, but how many Twinkies is that?

Re:Need a better measurement comparison

[wizardforce (1005805)]

Yes, but how many Twinkies is that?

heh.. just for the heck of it: mass of twinkie: ~35 grams, mass of sun =2*10^30 kg, mass of blackhole: 18*10^9 sol therefore, 18*10^9*2*10^30/35g*1000g/kg~= 10^42 twinkies.

Re:Need a better measurement comparison

[networkBoy (774728)]

You know, somehow that 42 is the exponent for number of twinkies in a black hole makes me worry about life, the universe, and everything....
-nB

Re:

[protolith (619345)]

Or you could say a Twinkie approximately 10^38 km long and weighing 3.5*10^37 metric tons.

Or 3.685*10^29 AU, (3.24810^24 Parsecs), 1.05*10^25 light years, room for about a billion of these in the universe!

"That's a really big Twinkie"

9.8 × 10^50 twinkies

[MyNymWasTaken (879908)]

Mass of an ordinary Twinkie: 36.4 g
http://www.mctague.org/carl/fun/twinkie/ [mctague.org]

Mass of the Sun: 1.99 × 10^33 g
http://www.google.com/search?hl=en&q=mass+of+the+sun&btnG=Google+Search [google.com]

1 solar mass = 5.47 × 10^31 twinkies

9.8 × 10^42 twinkies

[MyNymWasTaken (879908)]

Mental glitch - 18 billion = 1.8 × 10^9 ... not 18 × 10^18

I'm glad it's Friday. *headdesk*

Re:

[wizardforce (1005805)]

actually it's 1.8*10^10 not 1.8*10^9 (10^9=billion, 18 billion= 18*10^9=1.8*10^10)
2*10^30*1.8*10^10=3.6*10^40
3.6*10^40*10^3= 3.6*10^43
3.6*10^43/35=1.028*10^42

Gravity & Levity together in a black-hole

[OldHawk777 (19923)]

Yes, there is much gravitational distortion around a black-hole,
which looks like a very light-bright sphere (maybe a little
physically distorted) to all humans, and within the absence of
light there is much levity to consider.

Tell me again, why is it a big black-hole and not a big bright-spot?

In the absence of levity there is gravity.
In the absence of gravity there is levity.

Tag as Sun!Sol

[MtlDty (711230)]

Why do people say 'sol' instead of 'sun'. Is there some fundamental difference, or are they just trying to sound smart?

Re:

[kalirion (728907)]

It's equally silly to say The White House when there are plenty of white houses around, no?

gridwars

[doti (966971)]

This story makes me want to play gridwars2 [marune.de] again.

And again, and again...

Question about gravity

[caywen (942955)]

One question I have about gravity and black holes is this: If nothing can escape the event horizon, how can gravity escape it? In other words, would objects outside the event horizon ever feel the pull of gravity from that which is inside the event horizon?

Re:

[by Anonymous Coward]

Gravitational pull isn't something that is being radiated out of bodies. Just changes of it.

(In fact if the singularity somehow disappeared magically the outside world wouldn't detect it since the signal of black hole disappearing wouldn't escape from the gravitational well.)

Re:Question about gravity

[Ambitwistor (1041236)]

Other people have answered your question (radiation cannot escape from inside the horizon, but it can still generate a static external field), but here [ucr.edu] is a FAQ with more detail, including the quantum picture.

Re:

[JohnFluxx (413620)]

One hypothesis of gravity is that it is an exchange of 'gravitons'. If this hypothesis is indeed correct, then it does indeed make sense to ask how these gravitons can escape a black hole. And I don't know the answer to that.

But the most commonly accepted theory is that heavy objects cause the fabric of spacetime to bend under its mass - like a heavy ball placed on rubber sheet.
With this image, it is spacetime that bends so there's no meaningful question for how gravity 'escapes' from it.

Re:

[Ambitwistor (1041236)]

One hypothesis of gravity is that it is an exchange of 'gravitons'. If this hypothesis is indeed correct, then it does indeed make sense to ask how these gravitons can escape a black hole. And I don't know the answer to that.

Static gravitational fields are mediated by virtual gravitons, which can travel at any speed, including faster than light. However, you cannot use them to transmit information, i.e., changes in the field from inside the horizon.

With this image, it is spacetime that bends so there's no meaningful question for how gravity 'escapes' from it.

Right. Classically you can see that the exterior field does not depend on the interior field, and that gravitational radiation generated inside the hole can't get out.

Re:

[Ambitwistor (1041236)]

However, the mediating particles themselves are not affected by the force they mediate. Otherwise the universe would disappear up its own arse.
Hence, gravity is not affected by gravity.

Actually, most mediating particles are affected by the force they mediate, including gluons, the hypothetical gravitons, and IIRC the W bosons.

In gauge theory, a non-Abelian gauge group will in general lead to a nonlinear Yang-Mills theory with self-interacting fields, in contrast to the linear Abelian theory of electrodynamics.

Because gluons, the mediator of the strong nuclear force, themselves carry strong ("color") charge, it's possible for them to bind to each other. (See glueballs [wikipedia.org] in quantum chromody

Re:

[Ambitwistor (1041236)]

If I used my magic obliterator to magically make the sun disappear, would Earth go flying off into space at the same moment or would it continue to orbit the missing sun for the 8 minutes it would take the last rays of light to reach us?

The latter.

This is where they say gravitons come in as a particle that conveys gravity which doesn't make any sense.

Why doesn't it make any sense? Photons are particles which convey electric and magnetic forces, do you have a problem with them too?

Anyway, you don't need to appeal to graviton particles to answer the above question. Even in classical general relativity, the answer is still "8 minutes later", since that's how long for gravitational waves of spacetime curvature, traveling at the speed of light, take to reach the Earth.

That's incredible!

[renfrow (232180)]

Using this illustration [astro.utu.fi] and my trusty piece of paper straight edge, I estimate the long axis of the orbit to be 21000 AU and the minor axis to be 16000 AU. Using Ramunjan's Approximation [wikipedia.org] for the circumference of the elliptical orbit and converting to light years [glyphweb.com], I guesstimate the circumference of the orbit to be ~1.99 (call it 2) light years.

For a 12 year orbital period this means that the orbiting black hole is AVERAGING 1/6c (~49965km/sec, call it 50k km/sec)... meaning at periquaserion it's really booking! Much faster than The Dash!

Tom.

And so...

[Cleon (471197)]

I think this finally means that we have a definition for the SI unit "fuck-ton."

I see they used the term "Sol"

[not already in use (972294)]

For those of you who don't know, the term "Sol" means "A whale's vagina."

Re:

[by Anonymous Coward]

My googling says its even more impressive (http://curious.astro.cornell.edu/question.php?number=31) 100 billion stars in the Milky Way and most are smaller than the sun, so 18 billion makes it very greedy indeed!

Re:that's a lot

[HAKdragon (193605)]

Hawking: Homer, your theory of a donut shaped universe intrigues me

Re:

[Lijemo (740145)]

I'll save you all the time of googling this cuz I know you wanna know too. There's 200-400 billion stars in the milky way for example but most are bigger than our sun I think. So 18 billion solar masses is A LOT of stars to suck up in one galaxy. Geeze the think probably looks like a big donut by now.

Actually, my understanding is that the most common stars in the galaxy are Red Dwarfs, and thus smaller than our sun. (Yup, NASA confirms: http://planetquest.jpl.nasa.gov/glossary/red_dwarf.html [nasa.gov])

Re:

[El_Smack (267329)]

"What exactly is the mass of a hole? Besides a donut hole."

Well, I've read comments here over the years that prove the existence of Mass Holes.
Now I suppose we just find those users and weigh them.

Re:

[Mantaar (1139339)]

A "black hole" is not a hole like in your cheese - it's just a very sloppy term for an actual object with a higher-than-usual mass. So high, that it swallows all the light it might emit otherwise and thus appears to be totally black. Due to it's (assumed) look it's been dubbed a "black hole", though it's not really a hole - and it probably wouldn't be too dark around it, too...

The Hawking Evaporation or just random stuff that's falling into it (gas, particles) should emit a considerable amount of light. W

Re:

[AbsoluteXyro (1048620)]

It could be argued that the singularity of a black hole is an impossibly dense star. In which case, it would still be a solar system. However, it would only be a solar system if it had planets orbiting around it. It is highly unlikely that a black hole would have planets orbiting it, as the planets would have insufficient mass to keep from simply falling in to the black hole, that is to say the overwhelming mass of the black hole would place the barycenter of the black hole and any accompanying planet we

Re:orbiting blackholes?

[Ambitwistor (1041236)]

It is highly unlikely that a black hole would have planets orbiting it, as the planets would have insufficient mass to keep from simply falling in to the black hole,

If the Sun collapsed into a black hole, its gravitational pull on the Earth wouldn't change.

that is to say the overwhelming mass of the black hole would place the barycenter of the black hole and any accompanying planet well inside the event horizon,

Maybe you're talking about supermassive black holes, but if you're talking about black holes in solar systems, formed from collapsed stars, that's not true. A black hole is not "overwhelmingly massive"; it generally has less mass than the star it formed from, since some mass may be lost during the collapse. (Unless it gains a lot more later ...)

Furthermore, as the Earth-Sun barycenter is well outside the Sun's Schwarzschild radius, it would be outside the event horizon of a solar-mass black hole, too. Not that the location of the barycenter even matters to the stability of the orbit.

There are exoplanets — the first discovered, actually — known to orbit neutron stars, which are only 10-20 km in radius. There's no reason why planets couldn't orbit black holes too.

Re:

[Ambitwistor (1041236)]

The existence of a single solar mass black hole has nothing to do with any of the facts I stated. They hold no matter what the mass of the black hole, so long as it's not comparable in size to the planet's orbit itself.

(FYI, the smallest known black hole candidates are about 3 solar masses, with a size of about 18 km in diameter, i.e., about half the size of a neutron star.)

Re:

[sentientbeing (688713)]

A holer system.

Re:

[Arthur Grumbine (1086397)]

Neither of them are working for me today

"Today"?! How often do you feel the need to stare at a gaping anus?!?