Why Some Supermassive Black Holes Have Big Jets

astroengine writes "Some of the supermassive black holes at the centers of galaxies have powerful jets blasting from their poles, and others have weak jets, but many don't have jets at all. Why is this the case? In new simulations carried out by astronomers at NASA and MIT, it would appear that the way in which the black hole spins relative to its accretion disk may be a contributing factor. Strangely enough, the results indicate that if the black hole rotates in the opposite direction to its accretion disk, the most powerful jets form. The region between the black hole event horizon and the accretion disk still baffles scientists, so these simulations are very speculative, but the results seem to match what radio astronomers are seeing in the cores of active galaxies. Perhaps it's time to fire up that event horizon telescope!"

Comments

Here's a silly question

[drinkypoo]

Is there a name for the theory that all the missing dark matter is inside black holes?

P.S. Loved the mention of "space plasma" in TFA. It's not like regular plasma, it's space plasma.

Re:Here's a silly question

[endymion.nz]

Is there a name for the theory that matter is being sucked out of our universe as fuel for another?

Re:Here's a silly question

[drinkypoo]

Is there a name for the theory that matter is being sucked out of our universe as fuel for another?

Kind of hard to reconcile since black holes increase in mass as they draw in matter (aka mass.)

Re:Here's a silly question

[Merls the Sneaky]

They also decrease in mass by emitting hawking radiation.
http://en.wikipedia.org/wiki/Hawking_radiation

Re:Here's a silly question

[Rob Riggs]

MACHO: Massive compact halo object

An alternate theory is WIMP. You can imagine which ones the nerds prefer.

Re:Here's a silly question

[LowlyWorm]

That theory (whatever it may have been called if it ever formally was) has been largly discounted by many. Dark matter is surmised to exist because spiral galaxies seem to spin faster along their outer edge than would be expected were extra mass not there. On the other hand were there black holes along the outer edge of those galaxies one would expect to observe visible orbiting bodies around them.

Re:Here's a silly question

[Barrinmw]

They actually have direct evidence of Dark Matter. There were two galaxies that have started separating after colliding and the Gravitational Lensing from them shows that the Dark Matter didn't really react with anything and continued moving unimpeded whereas the regular matter slowed down.

So essentially, you have a large sphere of dark matter on each side of the separating galaxies with all the regular matter between them.

Re:Here's a silly question

[newcastlejon]

They increase in mass, yes but does their size increase? Where does the matter go if it's all compressed to a singularity? Are all the atoms just spaghettified, stacked one on top of the other in some infinitely tall, infinitely narrow well?

I have only a most basic grasp of cosmology but it's an interest of mine and I recall watching something on documentary heaven to the effect that black holes may well be a universe of their own. To be honest the very idea of a singularity still baffles me: it seems as though you start with an assemblage of simple, dull matter and in the blink of an eye any semblence to matter as we know it disappears and you're left with something that - to me at least - sounds like a feature of space itself.

Exactly what happens between the instant when you have a very, very dense lump of matter and an infinitely dense one? It seems an infantile question but where did all the matter go? Or was it transformed into something else that has mass but no size? Thinking about it gives me a headache and usually leaves me pondering whether any particles really have a physical size or if it's just another consequence of our limited view of the Universe.

Re:Here's a silly question

[Dragoniz3r]

Doesn't dark matter have to interact via gravity in order to be responsible for the things it's claimed to be responsible for? If that's the case, why didn't it react with anything? It's not as though the regular matter was interacting through electromagnetic, weak, or strong forces in any significant way during the collision. Gravity should have effected both types of matter equally, shouldn't it?

Re:Here's a silly question

[maxwell demon]

Yes, but this is all determined by what happens outside the horizon. Anything which happens inside the horizon cannot affect anything observable, including the observed black hole mass, outside of the horizon of the black hole (neglecting Hawking radiation; if a black hole radiates away, I'm not sure if anything inside could be revealed).

Re:Here's a silly question

[simcop2387]

Well what you need to do is forget the idea of a "singularity" (a division by zero, etc.) that's just an artifact from the math, and we've shown (i believe) that the math breaks down after you hit the event horizon (and possibly at the event horizon, i don't recall correctly). What this means is that we have no way of knowing or understanding what happens to the matter there.

Re:Here's a silly question

[osu-neko]

It did. What's observed is other things were impeded, whereas the dark matter passed through without any impediment, merely following a gravitational trajectory as anything would in the absence of anything to impede its progress along its trajectory.

Re:Here's a silly question

[Barrinmw]

Actually, math only breaks down at the Event Horizon, and physicists pretty much ignore that one point and continue on. Theoretically, due to all calculations, time at the singularity proceeds just like it does for a non-relativistic observer. And you can in fact, calculate the amount of time it would take for you to reach the center of the black hole, though somebody watching you would say it took an infinite amount of time since they see you as stopping at the Event Horizon. But to you, you actually reach the Singularity.

Re:Here's a silly question

[myrikhan]

But the mass-energy remains constant. Loss of mass in black hole = gain of energy from emitted photons

Re:Here's a silly question

[yndrd1984]

Doesn't dark matter have to interact via gravity in order to be responsible for the things it's claimed to be responsible for? If that's the case, why didn't it react with anything?

Right - it did react, but only gravitationally.

It's not as though the regular matter was interacting through electromagnetic, weak, or strong forces in any significant way during the collision. Gravity should have effected both types of matter equally, shouldn't it?

That's true for stars, planets, etc, but most of the baryonic matter matter in the Bullet Cluster is in the form of gas and plasma that does interact electromagnetically. Since gravitational lensing shows that the center of mass is still moving with the matter emitting visible light (stars), even though most of the rest of the mass we can detect directly (gas/plasma via X-rays) has been slowed, we can infer that there's a very massive component of the cluster we can't see that only interacted gravitationally.

Re:Here's a silly question

[LordofEntropy]

Wow, thank you everyone for the interesting and informative posts on this thread. Great to see some signal in the noise.

Re:Here's a silly question

[DJRumpy]

You may be thinking of the 'White Hole' theory.

http://curious.astro.cornell.edu/question.php?number=108

http://en.wikipedia.org/wiki/White_hole

Re:Here's a silly question

[Reilaos]

Or at least the mass that was you reaches the Singularity. You probably don't, as you are most likely dead.

Re:Here's a silly question

[DarkIye]

http://www.timecube.com/

It's probably in there somewhere.

Re:Here's a silly question

[Anonymous Coward]

They increase in mass, yes but does their size increase?

Yes, there is a direct relationship between the radius of the event horizon and the mass-energy within the event horizon. More massive or more energetic black holes have broader event horizons. This is observer dependent and subject to a Lorentz contraction, so if you are accelerating directly towards a black hole it will appear more massive (and thus have a larger radius) than if you are accelerating directly away from the same black hole; this effect increases exponentially as (absolute) relative velocity increases towards c.

When any observer sees mass-energy crossing into the event horizon, the event horizon's radius increases proportionately. Again an observer's measurement of that mass-energy is subject to a Lorentz contraction.

There is also an inverse relationship between the surface area of the black hole and its temperature; both are subject to the same Lorentz contraction, but more massive black holes emit photons similarly to colder blackbody radiators than less massive black holes.

Where does the matter go if it's all compressed to a singularity?

We have no useful theory about what's going on the inside of an event horizon.

There are several ways to consider the microscopic states inside a black hole from a thermodynamics-meets-General-Relativity perspective. Here's one. In GR (and we have tested this), the lower the gravitational potential in which a clock is, the slower it ticks, for any form of clock (including naturally oscillating processes). Ignoring observers experiencing acceleration other than via gravitation, the gravitational potential is very high in inter-galactic-cluster space (i.e., farrrr away from dense mass-energy), lower inside solar systems, lower still on planetary surfaces, very low inside stars, and extremely low inside black holes. Consequently, a "clock" ticking inside a black hole will, from the perspective of someone with a high gravitational potential, tick very slowly. The "clock" itself, however, will always tick at its natural rate, from its perspective and the perspective of anything immediately near by it, unmoving, and at the same gravitational potential.

So from our perspective on Earth, a natural oscillator inside an event horizon will go from oscillating at, say, several GHz, to oscillating less than once every several billion years of our time.

From its perspective our clocks on Earth will speed up by the same factor.

However, where things get strange is where the gravitational potential changes in distances shorter than the wavelengths of protons, neutrons, electrons, photons, and so forth, since they are ultimately oscillating "clocks". If "part" of a proton is in a higher gravitational potential than the rest of it, how do the quarks and gluons within it behave? What happens to the proton? And so forth.

That requires a consistent unified theory of gravitation and quantum mechanics, which nobody has been able to demonstrate yet.

Are all the atoms just spaghettified, stacked one on top of the other in some infinitely tall, infinitely narrow well?

Electrons, Protons, and Neutrons obey Fermi-Dirac statistics for fermions. Spatially, this means that you can't stack them all in one place - there is a pressure separating fermions from one another. When you introduce pressure from, for example, gravitation in a heavy star, it overwhelms the fermionic pressure and creates "degenerate matter". Neutron stars have degenerate phases including neutrons formed by squashing together electrons and protons. Quark stars may exist, and would have degenerate phases formed by squashing together heavy (i.e., full of neutrons) atomic nuclei. Pressures at and inside an event horizon would almost certainly lead to some further degenerate phase, and we have no idea what happens then.

(We can somewhat reproduce some

Re:Here's a silly question

[newcastlejon]

Firstly, thank-you for such a comprehensive answer, truly.

Actually, what more can I say? I think I'm love... always did have a thing for physicists.

Re:Here's a silly question

[Anonymous Coward]

No black hole we can indirectly observe actually loses mass, though: it would have to be of less mass than the moon to overcome even the background cosmic radiation, let alone the radiation in the environments we're observing. The black holes at the center of galaxies, well, they won't even be evaporating when the universe is twice as old as it is now.
 
I guess I shouldn't be surprised that we'd cite wikipedia without reading or understanding it.

Re:Here's a silly question

[jbssm]

But the mass-energy remains constant. Loss of mass in black hole = gain of energy from emitted photons

Yes, it remains constant in the universe, not within the black hole. In fact given enough time without accreting new mass, the black hole will dissipate. This was the most brilliant (of a long list of other brilliant) conclusion Stephen Hawking arrived; Not even black holes are eternal in case the Universe expands forever (and we already proved it will expand forever).

Re:Here's a silly question

[Chris Mattern]

They increase in mass, yes but does their size increase?

The only meaningful answer to measuring the size of a black hole is the radius of its event horizon, which depends solely on its mass, growing larger as the black hole's mass increases.

Re:Here's a silly question

[Chris Mattern]

In fact, tidal stresses will have reduced you to a fine red paste considerably before you even reach the event horizon. Cf Larry Niven's "Neutron Star"; while Niven's hero actually deals with a neutron star (as the story title implies) rather than a black hole, the same deal would exist with a black hole, only several orders of magnitude worse.

Re:Here's a silly question

[Barrinmw]

The math breaks down at the Event Horizon because of the expression

Delta Tau^2 = (1-2M/r)dt^2 - dr^2/(1-2M/r)

Where Delta Tau is the invariant interval, 2M is the Distance from the singularity to the event horizon and r is the reduced circumference.

At the event horizon, where r = 2M, the equation breaks down.

Re:Here's a silly question

[bronney]

You're educated stupid bro, the "black hole" he stated in his stuff isn't a collapsed star...

Re:Here's a silly question

[ErroneousBee]

My understanding is that the mass of a black hole is the frozen gravity field that existed just as the event horizon formed.

I really don't get the physics, but I don't see any particular reason the matter/energy that created the singularity has to remain 'in the hole' once spacetime has been distorted so much that time has stopped. Its like gravity has got stuck trying to get out of the hole, so we dont need the original mass any more.

Re:Here's a silly question

[Anonymous Coward]

The math breaks down at the Event Horizon because of the expression

Delta Tau^2 = (1-2M/r)dt^2 - dr^2/(1-2M/r)

Where Delta Tau is the invariant interval, 2M is the Distance from the singularity to the event horizon and r is the reduced circumference.

At the event horizon, where r = 2M, the equation breaks down.

Neither the math nor the physics break down at the event horizon, the Schwarzschild coordinates does for that particular spacetime, but that's just a problem with Schwarzschild coordinates. Much in the same way polar coordinates are not well behaved at 0, but the space R^2 is. There are several ways to check this, you could calculate curvature invariantes like the Kretschmann invariant and check that it doesn't blow up there, or you could use another chart (Kruskal-Szekeres for example) which are perfectly well behaved at the event horizon. The only true singularity for that spacetime is at r=0, the curvature actually becomes infinite at that point.

Unfortunately misleading messages like parent plague slashdot science oriented articles and get modded as informative.

Re:Here's a silly question

[Chaset]

Asimov's "The Gods Themselves" ? (I hope I have the title right... it's been nearly two decades since I read that)

are the jets tied to near by stargates?

[Joe The Dragon]

are the jets tied to near by stargates?

Re:are the jets tied to near by stargates?

[thoughtsatthemoment]

I think not. Even dialing to planet close to a black hole is very dangerous. Remember they used this trick to blow up a sun?

I found this article absorbing

[Anonymous Coward]

I was completely sucked in.

Re:I found this article absorbing

[mortonda]

I guess you understand the gravity of the situation...

Are they jets or starships...

[HouseOfMisterE]

...and why do they need them?

Re:Are they jets or starships...

[Anonymous Coward]

Are they jets or starships... ...and why do they need them?

I was wondering the same thing the first time I saw Xenu's fleet. As to their purpose, ask Tom Cruise.

Re:Are they jets or starships...

[MRe_nl]

This is Major Tom to Ground Control
I'm stepping through the door
And I'm floating in a most peculiar way
And the stars look very different today

I'm not qualified to read this article.

[eparker05]

My understanding was that black holes were a singularity. As for how something with no dimensions can spin, I am baffled. Perhaps my understanding of graduate level astrophysics is lagging a little.

Re:I'm not qualified to read this article.

[physburn]

You never see the singularity supposed at the middle of a black hole. A black hole, is normally defined by its event horizon a spherical (spheroidal for a spinning) hole, region light can't escape from. A black hole can have spin and charge, because these are both universally conversed quantities.

Re:I'm not qualified to read this article.

[Barrinmw]

But it's weird since the singularity is an infinitesimal point, its angular velocity would be infinite wouldn't it?

Re:I'm not qualified to read this article.

[wganderson12]

Black holes are regions of spacetime from which light cannot escape (nor can any other known form of matter or energy). The boundary of that region is called an event horizon. In classical General Relativity, there is a singularity inside the black hole. For a spinning black hole (described by the Kerr spacetime), this singularity is a ring around the axis of rotation, if that makes you feel any better. But in the end, talking about the motion of the singularity is meaningless - space and time do not exist in any normal sense at the singularity - it is called a singularity because the definitions of space and time break down there (the curvature of spacetime becomes infinite). If there is no space and no time, what does it mean to "rotate"? In fact, it is the spacetime at and outside the horizon that carry angular momentum (as compared to an observer at infinity). What that means is that objects near a rotating black hole which feel that they are locally "at rest" will still be rotating around the black hole from the perspective of an observer very far away from the black hole because the spacetime itself is being dragged around the black hole. Finally, for the record, singularities in spacetime are widely believed by physicists to indicate a failure of the General Theory of Relativity to describe extremely high curvature regions and not actual physical objects in our universe. We hope that if we can ever reconcile General Relativity and Quantum Mechanics that the resulting theory will be singularity free. Does that clarify things?

Re:I'm not qualified to read this article.

[Opyros]

Well, spin in quantum mechanics isn't quite the same thing as classical angular momentum.

Re:I'm not qualified to read this article.

[maxwell demon]

For a rotating black hole, the singularity is not a point, but a ring.

Re:I'm not qualified to read this article.

[newcastlejon]

A black hole can have spin and charge, because these are both universally conversed quantities.

If a black hole is an empty region of space with a honking great curvature then where is the charge? If it's the result of charged matter taking forever to actually reach the singularity how can the mediator cross the event horizon? If it's matter outside the horizon, is it properly considered part of the black hole; I assume that virtual particles are released equally as far as charge is concerned? What, exactly, in a black hole carries the charge. Come to think about it, how can we know they're charged at all? We can and have theorised it but is it even possible to verify experimentally?

Excuse me, I seem to broken my question mark key.

Re:I'm not qualified to read this article.

[Barrinmw]

From the calculations I have seen, for a singularity, time proceeds normally at that point as if there were no singularity at all.

Re:I'm not qualified to read this article.

[osu-neko]

My understanding was that black holes were a singularity. As for how something with no dimensions can spin, I am baffled. Perhaps my understanding of graduate level astrophysics is lagging a little.

Interesting. My understanding of conservation of angular momentum makes me intuitive think the exact opposite: how could a zero-dimensional singularly have anything less than infinite spin? However, as has been noted elsewhere, the "singularity" in a rotating black hole is not zero-dimensional, as it forms a ring rather than a point, so the question is kinda moot.

Re:I'm not qualified to read this article.

[Sir_Lewk]

If the spin of a black hole can be determined across a black hole, does that mean information can be transmitted across the event horizon?

Re:I'm not qualified to read this article.

[RulerOf]

What, exactly, in a black hole carries the charge.

I think it's related to the charge of the matter that's inside of it. Black hole eats 100 neutrons, 100 protons, and 99 electrons: positive charge.

It may not be that simple though, and I could be wrong. It's been a while.

Re:I'm not qualified to read this article.

[newcastlejon]

Inside what? Not inside any sort of zero-size singularity I assume but that still leaves the question of how a photon - don't they mediate the EM force? - can influence anything when it can't pass the event horizon, and if this is the case how could we ever measure the charge a black hole has?

Re:I'm not qualified to read this article.

[Urkki]

But it's weird since the singularity is an infinitesimal point, its angular velocity would be infinite wouldn't it?

Singularity of a rotating black hole might be a ring. At least the event horizon of a rotating black hole isn't a sphere. I think. Didn't check, may remember wrong...

Re:I'm not qualified to read this article.

[eparker05]

Wow, lots of responses.

My point was that many of us are armchair physicists. I don't know much about quantum theory or astrophysics other than the watered down versions of those subjects in popular press and on Wikipedia. Black holes are interesting and exciting, but I feel like a first grader hearing a description of calculus every time I read an article about them.

Re:I'm not qualified to read this article.

[MightyDrunken]

If I get your question right you want to understand how a black hole can hold charge and thereby influence things beyond the event horizon. Even though the event horizon prevents things inside from ever coming out again. It seems to me that if you assume the mass of a black hole is the property of only the matter inside it you have the same problem. Therefore it is better to consider the black hole as like a massive elementary particle from the out side which can have the following three properties; charge, mass and angular momentum. Note spin is different though similar to angular momentum and current theories treat black holes as having rotation NOT quantum spin.

Another perspective would be to consider an electron, how does an electron "hold" charge and influence space around it. If you can answer that then maybe you are close to how a black hole does.

Finally to measure a black hole's charge would be to compare the deflection of charged matter compared to neutral matter near it. So in theory it should be quite simple, though rather difficult in practise.

Too lazy to RTFA

[bytesex]

All of this is /observed/ or /theorized/ behaviour ?

Re:Too lazy to RTFA

[maxwell demon]

The existence of the different jets is observed. The cause is theorized, but fits with observations.

Re:Why don't you just ask

[binarylarry]

You must be in the NAACP:

http://abclocal.go.com/kabc/story?section=news/local/los_angeles&id=7475737 :(

Re:And the next question is...

[Vekseid]

Not all galaxies are feeding, so it's not necessarily 10%.

As a random thought: Due to the twisting of spacetime that a spinning black hole generates (frame-dragging), objects rotating against the rotation are going to face a stronger gravitational pull than those moving with it, to the point where the nearby surrounding space is moving faster than light - the 'ergosphere'.

Since feeding black holes tend to shut down their own feeding, it might be the case that the resulting outward pressure pushes away matter spinning in the same direction as the black hole stronger than it pushes away matter spiraling down in the opposite direction, eventually causing a reversal in the spin of the accretion disc.

Just a hypothesis, though.

I just assumed

[The Second Horseman]

That the supermassive black holes found that larger jets look slimming.

Re:And the next question is...

[grimJester]

. In addition, backwards spinning black holes will evolve over time and spin the other way, producing a weaker and weaker jet until it shuts off altogether.
It might be 50-50 to begin with. No clue why though.

What's the big deal?

[The Grim Reefer2]

Some of the supermassive black holes at the centers of galaxies have powerful jets blasting from their poles, and others have weak jets, but many don't have jets at all.

Some black holes are in a bigger hurry than others, hence bigger jets. While the ones that don't have jets are more concerned about the environment and galactic warming so they use public transportation.

How is it possible?

[Bysshe]

Can someone explain to me how its possible than an accretion disk can spin opposite to the black hole?

Is the spin of a black hole determined by the event that created it? For example the spin of the star that collapsed? And doesn't an opposing accretion disk create a lot of drag on the spin of the black hole?

Re:How is it possible?

[Barrinmw]

A body revolving opposite of it's rotation could cause the accretion disc to form that way.

Re:How is it possible?

[osu-neko]

I don't believe a black hole could initially form in a way that it spins opposite its accretion disk. However, it appears that most large galaxies today are the result of billions of years of collisions and mergers, so it's easier to see how such a state could come to be.

Re:And the next question is...

[osu-neko]

Since it now appears that many galaxies, and possibly every single spiral galaxy, is the result of galactic "collisions", I imagine that although in any undisturbed galaxy the central black hole will rotate precisely the way the rest of the galaxy does, following galactic mergers, things can end up a little topsy-turvy. The naturally tendency would be for these collisions and mergers of the central cores of galaxies to bias towards the existing spin (since it will influence the merger itself), so the majority of resulting mergers will maintain a spin in the same direction as the larger galaxy prior to the merger, in some cases, it's going to be a bit out of whack. Particularly after many repeated mergers (and there's evidence that many if not most larger galaxies end up gobbling up a number of smaller galaxies during their lifetimes), some are going to end up with core configurations completely opposite of their original state.

not for supergates

[Joe The Dragon]

not for supergates

Good reading here

[RulerOf]

I have only a most basic grasp of cosmology but it's an interest of mine and I recall watching something on documentary heaven to the effect that black holes may well be a universe of their own

One of my most favorite books on the subject is called The Five Ages of the Universe by Adams and Laughlin. If you like reading books about the subject but don't care about or can't comprehend the math, I seriously recommend it. That said (and I think it's in the book I linked), there's an evolutionary theory about universes that contends each time a black hole is created, it splits off a unique instance of spacetime creating a "new" universe with its own laws of physics. Universes created in this manner that contain laws of physics favorable to the creation of black holes will go on to evolve new "child universes" of their own; a sort of cosmic equivalent of Darwin's natural selection.

One more thing, should you find yourself occasionally staring at the TV and wanting to feel educated and entertained, then you should, uh, "acquire" a copy of Into the Universe with Stephen Hawking. It's a very well written and well narrated version of how Hawking explains the workings of the universe, but unfortunately isn't available on DVD yet. However, the trusty folks on the web that don't make any money from TV and movie distribution should have a copy you can pick up today ;)

The extremely fun thing about physics from a layman's point of view is that there are so many theories about how the same things work, and getting them presented to you in a manner you can understand without knowing the math behind it is a wonderful thing. From there, you can theorize and come to your own conclusions about which you like best, because if Planck has anything to say about it, we'll never truly know which of them is right.

It's kind of like going to a trade show, only instead of the place being full of vendors, it's full of missionaries from every major religion on the planet, and you get to objectively pick the one you like the best. I'm sure most Slashdotters would be drinking the free coffee at the Atheists' booth or ignoring everyone and speculating what the giant bundle of Cat5 on the wall goes to, but regardless of whether your God is supernatural or nonexistant, to glimpse into the very fabric and inner workings of the cosmos is the only true way to see into that mind.

Still, even if that's not the way you see it, I do feel that it's also the only way to even begin to fathom what we all really are.

Re:Good reading here

[Xaoswolf]

Universes created in this manner that contain laws of physics favorable to the creation of black holes will go on to evolve new "child universes" of their own; a sort of cosmic equivalent of Darwin's natural selection.

What happens when one black hole eats another?

Re:Good reading here

[RulerOf]

What happens when one black hole eats another?

Nothing special. The theory is that the "snap" happens at the moment a singularity is formed. It doesn't depend on it at all after that point.

Re:Good reading here

[drinkypoo]

What happens when one black hole eats another?

I don't know, I'll tell you year after next.

Wrong answered with wrong modded informative

[syousef]

For pity sake

1) The matter in a black hole isn't missing. It's accounted for. We can't know what kind of matter is in there because we can't know anything about stuff beyond the event horizon

2) We still don't know what Dark matter is, but we know that the so called WIMP model is most likely to account for most of it. We know this due to studies of objects like the bullet cluster of galaxies which can't be explained by MACHOs. In the bullet cluster, you see 2 galaxies that have collided - the normal matter in the form of gas and dust in each galaxy got slowed down, but the dark matter passed through each other. That wouldn't happen with MACHOs, and we would expect to be able to detect MACHOs in such a matter rich area by their microlensing events.

http://www.universetoday.com/2010/03/01/what-can-the-dark-matter-be/
http://www.daviddarling.info/encyclopedia/D/darkmat.html

3) What's even more interesting is that recent work suggests black holes do not absorb dark matter
http://www.universetoday.com/2010/03/22/astronomers-find-black-holes-do-not-absorb-dark-matter/#more-60422

Re:Wrong answered with wrong modded informative

[Merls the Sneaky]

black holes do not absorb dark matter
http://www.universetoday.com/2010/03/22/astronomers-find-black-holes-do-not-absorb-dark-matter/#more-60422

So this would suggest the darkmatter particle has no mass, travels faster than light or both?

Re:Wrong answered with wrong modded informative

[syousef]

black holes do not absorb dark matter
http://www.universetoday.com/2010/03/22/astronomers-find-black-holes-do-not-absorb-dark-matter/#more-60422

So this would suggest the darkmatter particle has no mass, travels faster than light or both?

I skimmed their journal article on arxiv. At this stage all they've shown is that there is an upper limit to the amount of matter in the central region of a galaxy given that we don't see a "runaway accretion" (presumably the whole galaxy goggled up by the black hole?). They conclude this suggests that the centers of galaxies have constant density.

So they seem to be saying dark matter doesn't live there (or that there is a limit to it) and that is how it avoids being sucked into the black hole.

Re:Wrong answered with wrong modded informative

[jbssm]

So this would suggest the darkmatter particle has no mass, travels faster than light or both?

Actually, none of the hypothesis. According to the article (and broader theory) it only means that either the distribution of dark matter in the galaxies is not has expected, or that it may be following a non Newtonian gravity law (yes, I know, we have something better than Newton laws nowadays, but the therm is used broadly to describe a theory in which the force of gravity doesn't decrease with the square root of the distance between masses).

Re:Wrong answered with wrong modded informative

[drinkypoo]

3) What's even more interesting is that recent work suggests black holes do not absorb dark matter

What's even more interesting is that your link doesn't suggest that black holes do not absorb dark matter:

The researchers modeled the way in which the dark matter is absorbed by black holes and found that the rate at which this happens is very sensitive to the amount of dark matter found in the black holes' vicinity. If this concentration were larger than a critical density of 7 Suns of matter spread over each cubic light year of space, the black hole mass would increase so rapidly, hence engulfing such large amounts of dark matter, that soon the entire galaxy would be altered beyond recognition.

It doesn't say they don't absorb it, only that our assumptions of how they would absorb it are wrong. It also says dark matter resists 'assimilation' into a black hole, not that it is immune to it. If they actually meant to say that it cannot be absorbed by a black hole, they need to study English, because they utterly failed everywhere but the subject, which does not agree with the article.

One theory...

[mikael]

... is that the black hole is composed purely of dark matter, and the intense gravity strips the dark matter (ie. mass/gravitational attraction) from the charged particles (protons/electrons), which then repel each other as jets, while the dark matter just consolidates into the black hole.

Is it really surprising?

[liquiddark]

Black hole rotating in reverse relative to its accretion disk has the highest energy of particle interactions at the hole-disk boundary just as two particles travelling towards each other have a higher energy collision than two traveling in parallel. One would, naively, assume that that was the highest energy configuration, although how it gets to be that way in the first place is still an interesting question. I assume objects must have been captured and are now revolving about the hole in a direction opposite to its spin.

M-Theory expansions

[chronoss2010]

they used to say the beginning of the univrse was a singualrity too WITH added dimension of the 11th , htey were able mathmetically get round this.

ITS entirely possible like whats obviousl and hte KISS idea of the most simple is most often the way things work.

IT is said there is a dimension where all gravity resides its one reason why gravity as a force is actually so weak. What maybe happening is that black holes are punching or getting back into that dimension but just cant quite get all way there cause of dimensional boundaries thus while stuck here they are close spots of dimensional boundaries too the gravity dimension.

The size was only about a few microns of this dimension so imagine if all the black holes in the universe were trying to push/get pulled into this dimension....

reason why white hole theory cant be right is because it just makes little sense then why black holes exist so long and why they just wold not poor out into a new universe or to other places in the universe which NO astronomer has yet to see in our universe or that black holes are leaching enough to account for a white hole to another universe.

i have a interesting theory on dark matter but with the math and such it does get harry.
easy to think up.
fill a balloon with water
hold it up
pin prick it
see the water come out NOT straight down but it sprays out in a cone shape
thats kinda how the universe is and why there is no center cause all the matter just rushed out and , my idea is that the reason the universe is speeding up away isn't for lack a gravity its cause we like the water are falling to the FLOOR of the dimension we are in

dark matter is bits and pieces fo the invisible dimensional wall and dark energy would be the type of particles created in the collisions of the two dimensions.
If you think of an object falling it increases in speed like how the galaxies appear to be speeding up not slowing down.

The big question is when are we hitting bottom and then what happens. Haven't worked the math on that yet.

think M-theory

[chronoss2010]

When the two dimensions that create the universe collided there was bits and pieces of the dimensional walls that were riped apart and got sent into our "universe" they might have mass just in a way we cant see yet. ITS real hard math to get at that part of the theory and while the math says the collision between two universes/dimensions is how we began the video showing it showed two walls rubbing each other and then a tear along that well if multiple tears .....then is it not possible that parts of the two universes that collided have "other parts that got sent into our universe.....would that be account for something that while it might have mass can't be sens and might pass through other mater yet kind of attract to its other floating bits.

With the gravity dimension being where all gravity exists and comes out it might be conceivable that this is why its so weak on this type of "wall pieces" of the colliding universes. CAN anyone speculate on this idea or possibility

could that lend to the idea of it being

[chronoss2010]

part of the two universes that collided and tore and all matter came through and pieces of the walls of the two creator universes also came it, as the dimensional boundary is lowest on the gravity totem pole and is basically invisible to all matter moving through it , but on larger scale might have some kinda mass might it not surmise that large chunks that got sent into this new universe also got a "bit of the dimensional or universal creators walls ?

UGH ya my head is now starting to hurt too LOL

well

[chronoss2010]

only way i see or you see that in natur othr then this is when we force it to be that way SO maybe its something that in its past that isn't apparent that made it do it this way what planet is it in our solar system they cant explain rotates oddly.....neptune?

Why the hole gotta be black?

[thefekete]

County commissioner laments the color choice for "black" holes:

http://www.youtube.com/watch?v=YAw5D1-8IrQ#t=39s (sorry, bad audio)

Re:The Electric Universe

[IRWolfie-]

They appear to claim there is no nuclear reaction inside stars, yet stellar models successfully model stars when this is taken as the mechanism of energy release to counter-balance gravitational contraction, which is the mechanism of light emission from stars.

These Guys is why...

[DarthVain]

http://billwardwriter.com/wp-content/uploads/2010/02/blackhole-vincent-bob.JPG

The Theory of Black Holes Leading to New Universes

[Favonius Cornelius]

I have a very simple problem with this theory: if a black hole creates a new universe with the mass it has collected, then isn't that universe quite small compaired to our own? When a new universe is formed is mass and energy created? Is the universe ours is from that much more massive?