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Why do some of the supermassive black holes in active galactic nuclei create back-to-back jets that can vaporize entire solar systems, while others have no jets at all?
Dan Evans, a postdoctoral researcher at MIT Kavli Institute for Astrophysics and Space Research (MKI) thinks he knows why; it’s because the jet-producing supermassive black holes are spinning backwards, relative to their accretion disks.
For two years, Evans has been comparing several dozen galaxies whose black holes host powerful jets (these galaxies are known as radio-loud active galactic nuclei, or AGN, and are often DRAGNs – double radio source associated with galactic nucleus) to those galaxies with supermassive black holes that do not eject jets. All black holes – those with and without jets – feature accretion disks, the clumps of dust and gas rotating just outside the event horizon. By examining the light reflected in the accretion disk of an AGN black hole, he concluded that jets may form right outside black holes that have a retrograde spin – or which spin in the opposite direction from their accretion disk. Although Evans and a colleague recently hypothesized that the gravitational effects of black hole spin may have something to do with why some have jets, Evans now has observational results to support the theory in a paper published in the Feb. 10 issue of the Astrophysical Journal.
Although Evans has suspected for nearly five years that retrograde black holes with jets are missing the innermost portion of their accretion disk, it wasn’t until last year that computational advances meant that he could analyze data collected between late 2007 and early 2008 by the Suzaku observatory, a Japanese satellite launched in 2005 with collaboration from NASA, to provide an example to support the theory. With these data, Evans and colleagues from the Harvard-Smithsonian Center for Astrophysics, Yale University, Keele University and the University of Hertfordshire in the United Kingdom analyzed the spectra of the active galactic nucleus with a pair of jets located about 800 million light years away in an AGN named 3C 33.
“It’s the first convincing galaxy of this type seen at this angle where the result is pretty robust,” said Patrick Ogle, an assistant research scientist at the California Institute of Technology, who studies AGN. Ogle believes Evans’s theory regarding retrograde spin is among the best explanations he has heard for why some AGN contain a supermassive black hole with a jet and others don’t.
Astrophysicists can see the signatures of x-ray emission from the inner regions of the accretion disk, which is located close to the edge of a black hole, as a result of a super hot atmospheric ring called a corona that lies above the disk and emits light (electromagnetic radiation) that an observatory like Suzaku can detect. In addition to this direct light, a fraction of light passes down from the corona onto the black hole’s accretion disk and is reflected from the disk’s surface, resulting in a spectral signature pattern called the Compton reflection hump, also detected by Suzaku.
But Evans’ team never found a Compton reflection hump in the x-ray emission given off by 3C 33, a finding the researchers believe provides crucial evidence that the accretion disk for a black hole with a jet is truncated, meaning it doesn’t extend as close to the center of the black hole with a jet as it does for a black hole that does not have a jet. The absence of this innermost portion of the disk means that nothing can reflect the light from the corona, which explains why observers only see a direct spectrum of x-ray light.
The researchers believe the absence may result from retrograde spin, which pushes out the orbit of the innermost portion of accretion material as a result of general relativity, or the gravitational pull between masses. This absence creates a gap between the disk and the center of the black hole that leads to the piling of magnetic fields that provide the force to fuel a jet.
While Ogle believes that the retrograde spin theory is a good explanation for Evans’ observations, he said it is far from being confirmed, and that it will take more examples with consistent results to convince the astrophysical community.
The field of research will expand considerably in August 2011 with the planned launch of NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) satellite, which is 10 to 50 times more sensitive to spectra and the Compton reflection hump than current technology. NuSTAR will help researchers conduct a “giant census” of supermassive black holes that “will absolutely revolutionize the way we look at X-ray spectra of AGN,” Evans explained. He plans to spend another two years comparing black holes with and without jets, hoping to learn more about the properties of AGN. His goal over the next decade is to determine how the spin of a supermassive black hole evolves over time.
Sources: MITnews, Evans’ Astrophysical Journal paper (preprint is arXiv:1001.0588)
Well, that’s an interesting theory. I’ll have to read the paper as soon as possible.
I wonder if there is an implication for less extreme objects as well (jets from T Tauri objects, e.g.)?
Awesome, if a fact!
[Plus it will kill EU nutters that the magnetic fields is constrained by the BH gravitation/disk mass accretion process and not the holiest of holy Z-pinch/plasma current way around. ;-o]
I just learned today that you can use the OAM and associated light pulse flank modes of light to probe the BH rotation twisting spacetime and so light around. There’s a whole world of remaining observations to do out there, tweaking ever more information out of simple light.
@Torbjorn
I doubt that EU fanatics actually have understood one line what you just said. LOL
I read the paper. The study is focused on explaining the absence of a Compton reflection hump in 3C33 and the nature of Fe ion emissions. What this article does not mention is there are actually two conclusions, which require further, more detailed study to determine which is correct:
Ionized Accretion Models
A fully ionized central region would be consistent with a z-pinch, at or beyond the EM density required to produce an extended fully ionized region and energetic jets. Most galactic z-pinches are within the “glow mode” regime of current density, while most AGN are within the “arc mode”, which is when the fully ionized central regions and more energetic jets would occur. The lack of Fe emission would indicate particle sorting by strong EM/ES fields associated with charge sheath layers.
Retrograde Black-Hole Spin
Point 5 of 5 in the “Conclusions”:
peace,
solrey
How would a BH get to rotate backwards from its disk in the first place?
I like this proposition a lot – it would be a very elegant explanation indeed…
solrey:
So then, solrey, when do you expect to win the $1 million Shaw Prize for astronomy, as a result of your wonderful insight (!)? I’m sure that you can teach Prof. Reinhard Genzel, the winner of the 2008 Shaw Prize, a thing or two (!).
N.B. (!) = Sarcasm.
Which way is normal/forward? WRT BH’s of any size?
and
“general relativity, or the gravitational pull between masses. This absence creates a gap between the disk and the center of the black hole that leads to the piling of magnetic fields that provide the force to fuel a jet.” IMWTF????
This is half correct “magnetic fields that provide the force to fuel a jet” , but no mention of the electric fields, double layers, Birkeland currents and other stuff?
“Black holes are where God divided by zero.” — Steven Wright
Beautiful 🙂
sol88:
Why no mention from the EU/PC brigade of what is the bloody power source of those alleged “electric fields, double layers, Birkeland currents and other stuff”?
Hmm… the copy & paste job of that above blockquote did not turn out correctly, but it’s clear enough.
what is the bloody power source of those alleged “electric fields, double layers, Birkeland currents and other stuff”?
Lets find out!!!
Question:
if this is true what happens if A. blackhole spinning one way comes close to B. blackhole spinning the other way?
I am pondering the astrophysics of this. For a nonrotating black hole the accretion disk can rotate in any direction. That is fairly obvious. A rotating black hole will in effect rotate space along with it, which becomes extreme sufficiently close. In fact there is a region where being frame dragged along with the rotation of the black hole can not be physically opposed. This region is called an ergosphere. So does this influence the rotation of an accretion disk? Probably, but for a distance R >> 2GM/c^2 this influence is weak. If you are located at a radius say 100 times the radius of a black hole the influence of this rotational frame dragging, or Lense-Thirring effect, is pretty weak. A cloud of gas that is gravitationally attracted to the black hole can have a net angular momentum oppositely directed from that of the black hole. This would set up an accretion disk which rotates in the opposite direction as the rotation of the black hole.
Things change though for the accretion disk material which enters the ergosphere of the black hole. There the frame dragging becomes irresistible. If you throw a chunk of material towards a rotating black hole along the equator (such as where we might expect an accretion disk to lie) the spacetime momentum of the material p_a remains constant along a vector K^a which describes the isometry of the spacetime. K^a is a Killing vector, termed after a person so named, and the index a runs over spacetime coordinates in some chosen frame. The change in this with respect to what is called covariant coordinates in p_aK^a = constant is zero, but if we equate p_a = p1_a + p2_a for an ingoing and outgoing quantity of matter it is possible to show that the outgoing matter will have greater mass energy than the initial ingoing matter. In effect infalling matter must change its angular momentum direction by “mining” the energy of angular momentum in the black hole. So the portion of matter which escapes does so with greater mass-energy than what was contained by the infalling mass-energy. So this is a lot of energy!
Hence an accretion disk with a counter rotation or oppositely pointed angular momentum from the black hole sets up a situation where the energy of angular momentum (in a simple classical condition is E ~ J^2/2, J = angular momentum) of the black hole is extracted and can throw out material at relativistic velocities. This can certainly provide the energy required to set up these jets. The physics for how these jets actually form then of course involves how this energy is converted into magnetohydrodynamic energy which configures the plasma jet. An SMBH in an AGN will then have episodes where gas clouds approach the BH and the angular momentum of these gas clouds may vary. So there could be active periods where the gas cloud has oppositely directed angular momentum and power jets are established. In the case where the gas cloud has angular momentum directed along that of the black hole, this may then “recharge” the black hole’s reserve of angular momentum and energy associated with it.
LC
Wow. I bet that’s a violent place to be. I’m also wondering if a black hole merger or collision might induce an opposite spin if they hit just right. In some cases one of them is kicked out of the core, and even out of the galaxy, but I reckon there would have to be some effect on the remaining one. I’m sure some computer modeling might work that out. LC’s post makes sense, though (as always).
Granted, IANAP, but driving down the highway and shifting into reverse can cause lots of chaos…especially if there’s a lot of traffic.
Jean,
The z-pinch hypothesis comes from Alfven, Peratt and several others.
A sampling of some of Peratt’s papers:
Evolution of the Plasma Universe: I. Double Radio Galaxies, Quasars, and Extragalactic Jets.
Evolution of the Plasma Universe: II. The Formation of Systems of Galaxies
Advances in Numerical Modeling of Astrophysical and Space Plasma
Advances in Numerical Modeling of Astrophysical and Space Plasma, Part II Astrophysical Force Laws on the Large Scale
Regarding Birkeland currents. Birkeland currents are a term for magnetic field aligned currents in general, which are observed throughout space.
The term is relevant to more than just planetary magnetospheres.
Birkeland Current
Cosmic electric currents and the generalized Bennett relation
The Bennett relation is relevant to magnetic field aligned currents, a.k.a. Birkeland currents.
The universe is 99% plasma, therefore it makes sense to model the universe as a complex, dusty plasma and observations do support this theory.
ivan3man,
Here’s what Genzel actually discovered:
He didn’t discover a black hole, he calculated the mass at the core of the galaxy based on the orbits of stars near the center. Thing is, those stars aren’t supposed to be there in the standard model and how they got there is still an open question. The existence of those stars is not un-expected in the plasma cosmology model, due to fissioning/sputtering of the central plasmoid and/or created in pinches between/within inflowing filaments. Their orbital velocities may also be influenced by EM/ES fields surrounding the core, which would result in calculated mass being much higher than it actually is.
peace,
solrey
How a supermassive black hole came to be rotating in the opposite direction to its accretion disk is certainly an interesting question. DRAGNs tend to be in giant ellipticals, often the brightest cluster galaxies, and may be powered by cooling flows. The spin of a supermassive black hole in such an AGN would be a result of the complex history of its growth.
solrey,
I’ve never heard of z-pinch AGN hypotheses, and can’t find any in the literature. Is this your own idea?
sol88,
You wouldn’t see any mention of Birkeland currents, because this term is use only in the study of planetary magnetospheres (and related phenomena); electric fields, double layers, and the rest are all part and parcel of the physics that is included in models of accretion disks.
Jean,
I think it is less about how the black hole came to be rotating oppositely directed from the accretion disk, but rather visa versa. A black hole might sit at a galaxy center with relatively little activity nearby. Then a large gas cloud orbits in, and depending on these initial conditions it orbital angular momentum is directed with or opposite the angular momentum of the black hole. Then the gas cloud condenses into the accretion ring and disk and eventually its matter is either violently gobbled up or explosively sent out into space in jets. There are black hole thermodynamics behind this as well.
It does make sense this happens most with elliptical galaxies, which has a small angular momentum — as far as I know. A spiral galaxy has a well defined structure and most of its material orbits with the same direction of angular momentum. Again as far as I am aware jets are not commonly seen from spiral galaxies.
LC
Jean,
Why did you not even mention the other possible conclusion of the paper related to high/full ionization? I can understand from an editorial pov that a sensational title catches the readers attention, but what’s the motivation for totally ignoring the other equally plausible half of the paper in the body of the article?
peace,
solrey
Not all accretion disks are created equal.
The theory goes, if the stellar winds can affect a body, then the mass of the accretion rate will be large enough to remove angular momentum from it. So any gas is going to lose its AM.
However, if something like a star falls within the grips of a black hole, then the accretion disk will likely form along along the path of the star moving around the black hole. Since it will maintain its AM.
Anybody who has watched the latest film of stars moving around our galaxy’s SMBH has seen there are quite a few stars moving in all directions around it.
There is also evidence showing quasi periodic oscillations can have an affect on an accretion disk due to the interaction with the magnetosphere. So having a highly eliptical orbit around the BH is another factor; along with whatever crazy and variable magnectic action is going on.
The final well known variable has to do with temperature. If the material within the disk is relatively cool… then there will be a nice fine accretion disk. However, if the material is hot, getting hotter or not being cooled, then the accretion disk can be wide, not so neat and just as variable as the black hole itself.
In the simplest forms… if there is just one item feeding the BH and moving in the same general direction, then the accretion disk is going to be relatively neat and orderly… add another item feeding the black hole or going in an opposite direction, plus the magnetic energy…. there appears to be what amounts to accretion disk turbulence…. giving rise to jets.
So I’d say Evans has a good point worth looking and listening to.
Yes, solrey, and where is the magical central plasmoid that controls and spouts out all the stars there? Oh, I forgot. It’s in the magical “dark mode” again, how convenient.
@ Jean Tate
Whenever there are “Birkeland currents”, “z-pinches”, “double layers”, etc mentioned, I hear alarm bells ringing in my head.
Folks using these terms here are normally considered to belong to a religion-like group who intend to replace common knowledge with BS. In their little world GR and the Big Bang are non existent, and everything in the whole universe is explainable with plasma physics. Stars are powered with some weired interstellar currents (although they fail to explain where they come from, what powers them, and why we don’t observe them…) and not with fusion. Magnetic fields hold galaxies together instead of gravity. The sun is supposed to be charged (a net charge with a potential of 10 Billion Volt!!).
And many more strange ideas.
Folks dealing with these matters are normally marked as trolls here.
Debating with them is (sadly enough) useless, we have tried so for about a year.
drflimmer, actually that terminology is entering the vernacular of current mainstream research in astrophysics.
Since some of us are met with unkind words for making the same statements, here are some magnetism facts from NASA:
The first two are:
Also, electric fields in the sun have been studied for many years as this paper from 1991 demonstrates.
http://articles.adsabs.harvard.edu//full/1991ApJ…383..450C/0000450.000.html
And data that will come from the newly launched SDO is said to be poised to “re-write the books” about the sun. Are they hinting to a possible falsification of the fusion model perhaps?
Plus, EU/PC has always included the force of gravity and it’s relative strength to EM/ES fields in the balance of forces in a model that fits observations without requiring the addition of adjustable parameters like dark matter/energy/flow and black holes.
And don’t forget when speaking of religion-like followers that the “father of the Big Bang”, Georges LeMaitre, was a Catholic priest.
peace
I am not a plasma physicist, but some of these terms refer to real physical concepts. The PU wogs though take these terminologies and put them in a word salad of jargon and claim to “know it all.”
LC
Solrey:
Why did you put this in bold? Everyone knows this. Field lines are a visualization aid. Like contour lines on a topographic map.
Electric field lines don’t exist either. These are classical realizations of something more fundamentally understood with quantum mechanics. These guys don’t appears to understand much about electromagnetism. Anaconda was not able to calculate the impedance of the vacuum These guys just stir EM jargon together in a stew of nonsense.
LC
Those “Electric Universe” guys — and it appears to be only male electricians who are obsessed with that ‘theory’ — are rather like presidential hopeful Sarah Palin who thinks that just because she can see Russia from her house in Alaska, that automatically makes her qualified in foreign policy and diplomacy; it’s the same with those “Electric Universe” obsessed electricians who think that just because they know how to rewire a bloody building, that makes them bloody experts in astrophysical phenomena in the the whole bloody Universe!
D’OH! Why is it that I always notice grammatical errors, such as that double “the”, after I’ve posted the bloody comment!
I also forgot the “?” after that last comment!
Answered in two of the most important quotes in history!!
Throughout space there is energy. Is this energy static or kinetic! If static our hopes are in vain; if kinetic — and this we know it is, for certain — then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.
And
Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe.
Nikola Tesla
solrey,
Thanks for your comments; I’ve edited the article, and added a paragraph on how NuSTAR may test Evans’ ideas.
Ideas stand or fall on the scientific merits, and the material you posted has nothing to do with DRAGNs, or even AGNs; Peratt’s stuff, for example, is about the formation and evolution of galaxies (and, while certainly creative, clearly fails).
I would be most interested to learn of extra-galactic astrophysics papers, from the last ten years, which use the terms Birkeland current, z-pinch, or Bennett relation (as I said earlier, I could find none).
sol88 (and solrey),
There is a good Astronomy Cast episode that I recommend you check out: How to Be Taken Seriously By Scientists.
@ solrey:
As usual from the EU/PC brigade, most of them are outdated papers from the late 1980s, and just two ‘recent’ papers from the late 1990s. You EU/PC guys are just like audiophiles who insist that vinyl records are superior to CDs, and who don’t think twice about bidding thousands of Dollars/Euros/Pounds on eBay for a vacuum tube amplifier — which, judging by the interior photographs of the rather basic components, I could put one together for less than a hundred bucks!
I never said that Prof. Reinherd Genzel discovered a black hole, and I was already aware of his work in determining the mass of the object — by observing the orbits of the stars around it — at the centre of the Milky Way.
So what? According to the Max-Planck-Institute for Extraterrestrial Physics, future observations are already being planned to test several theoretical models that try to solve this riddle: (1) that these are old stars masquerading as youths; (2) that they were formed more or less in-situ by a cataclysmic compression of an already dense cloud or disk; and (3) that they were formed elsewhere as part of a massive cluster, but migrated inwards rapidly by dynamical friction. (Source: Stellar Orbits Around the Galactic Center Black Hole)
Oh, you mean just like the 9/11 attacks on the World Trade Center Towers was “not unexpected” amongst psychics (!)?
Now look here, dude, we’re talking about an object at the Galactic Centre with a mass of about 4 million solar masses, which was determined from the motion of star S2 observed over a 16 year period! That’s some bloody ‘plasmoid’ there (!).
From observations, we also know that the radius of the central object is significantly less than 17 light-hours; because otherwise, S2 would either collide with it or be ripped apart by tidal forces. In fact, recent observations indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus’ orbit — the only known astrophysical object which can pack ~4 million solar masses into a volume that small is a bloody black hole!
DrFlimmer, if I have missed anything out, feel free to fill-in the details — for what it’s worth!
@ sol88,
Extract from Wikipedia — Nikola Tesla:
The dream of vacuum energy is similar to trying to get potential energy from the sea level. If you have a lake it is true there is energy is the gravitational potential in each mass-layer of water. However, physics is not very forgiving. In order to get that gravitational potential energy from a water level that water must flow into a lower level. If all there exists is water at a single level then the potential energy in the fluid is inaccessible. That energy is in an equilibrium configuration.
The quantum vacuum is similar to this analogy. The zero point energy of the quantum vacuum results from a quantization condition on harmonic oscillators. The Harmonic oscillator turns out to be a mathematical tool used to describe the quantum physics of particles which are created or destroyed according to a vacuum state. There is a residual energy for the no particle or vacuum state. This can be rather trivially removed by a simple procedure called normal ordering. If there were regions of the universe with different vacuum energies there would be at this boundary the production of particles or energy. Do these boundaries exist? In a manner of speaking yes. A baryon or proton is a region with a confined QCD vacuum that has considerable amounts of energy. Much of this energy in the confined region is what determines the mass of a proton. In some grand unification theories protons decay, which is a quantum field analogue of two water levels. It just takes a considerable time for the probability for this to happen as a quantum fluctuation or tunneling event. A black hole is another example, where the black hole polarizes the vacuum around it. Even excited atomic levels and energy stored in molecular configurations is an example as well. So there is vacuum energy in a sense that is accessible, but only because the vacuum is associated with excited states as well. In other words, the energy involves ordinary matter.
LC
@ IVAN3MAN
Dude was right though eh!
Don’t matter if YOU think he is worshipped by fringe groups, dude was right!
i.e Gravity only cosmology is the static and our hopes are in vain.
EU/PC is dynamic so are hope are not in vain!
Point in hand,
TSS-1R mission and Electrodynamic power!
And Biefeld–Brown effect
@ sol88,
When you EU/PC guys succeed in producing your perpetual motion machine, then you can come and crow here; however, you will not succeed because the Universe is governed by Sod’s Law: The degree of failure is directly proportional to the effort made and to the need for success. 😉
@lbc
Why calculate? The impedance of vacuum is a fundamental constant.
The approximate value is 376.730313461 ohms
In wired circuits, alternating current impedance is resistance plus the phase of the current (reactance). For direct current, impedance is the same as resistance. For plasma in free space the resistance will approach, but not equal, zero.
I think you don’t even know what you’re asking there, lbc.
peace,
solrey
@ solrey,
LBC knows very well what he did ask of Anaconda; it was a trick question and he fell for it!
Lawrence B. Crowell, Aodhhan, and others,
The details of Evans’ model of supermassive black holes with retrograde spin are in an ApJ paper that has been submitted but not yet published. With two colleagues, he presented it at the recent AAS meeting.
@ Ivan3man
I think, your point is clear enough. I have nothing to add!
Solrey’s commet speaks for itself. SDO to overturn the fusion model:
http://www.flickr.com/photos/badastronomy/2781702559/
and PU describes all we see in the universe. Yeah. Strangely enough, still the solar wind isn’t effected!
And the Big Bang was invented by a Catholic priest. Yeah, and? I believe in god myself. But I know the difference between science and religion.
And Newton was, according to Dan Brown, the head of a secret sect to guard the offspring of Jesus Christ.
And sadly enough: This blog has been peaceful for quite a while. Why had this thread to turn into this mess, again?
The point about LeMaitre and magnetic field lines… I mean wtf? They make no sense. They’re just red herring and they keep bringing it up. Is this willful deception on their part are they just ignorant of scientists working in the field? Solrey, what exactly was your point about field lines?
Also we can blame Torbjorn for putting those two letters together in the second post to this thread. I think it’s painfully aware now that those two letters open up an interdimensional gateway allowing crankpots to infiltrate whatever blogospheric node in which those letters were invoked. Those letters that shall not be named are the 69th and 85th in the ASCII table.
Solrey: The impedance of space is deduced from Maxwell’s equations, and the electric dielectric constant and magnetic permittivity. Using the plane wave solution to the Maxwell-Faraday equation, the impedance is found in connection to the current density in an Ohm’s law expression where R = sqrt{mu/eps}, where mu and eps are more fundamental.
Thanks Jean for the reference.
As for Lemaitre, who cares whether he was a priest!? He advised the Pope later not to take the model as something in the Catholic canon.
LC