Study explains decades of black hole observations

Jun 14, 2013 by Susan Gawlowicz
This annotated image labels several features in the simulation, including the event horizon of the black hole. Credit: NASA’s Goddard Space Flight Center

(Phys.org) —A new study by astronomers at NASA, Johns Hopkins University and Rochester Institute of Technology confirms long-held suspicions about how stellar-mass black holes produce their highest-energy light.

"We're accurately representing the real object and calculating the light an astronomer would actually see," says Scott Noble, associate research scientist in RIT's Center for Computational Relativity and Gravitation. "This is a first-of-a-kind calculation where we actually carry out all the pieces together. We start with the equations we expect the system to follow, and we solve those full equations on a supercomputer. That gives us the data with which we can then make the predictions of the X-ray spectrum."

Lead researcher Jeremy Schnittman, an at NASA's Goddard Space Flight Center, says the study looks at one of the most extreme physical environments in the universe: "Our work traces the complex motions, and turbulent magnetic fields in billion-degree gas on the threshold of a black hole."

By analyzing a of gas flowing into a black hole, the team finds they can reproduce a range of important X-ray features long observed in active .

"We've predicted and come to the same evidence that the observers have," Noble says. "This is very encouraging because it says we actually understand what's going on. If we made all the correct steps and we saw a totally different answer, we'd have to rethink what our model is."

Gas falling toward a black hole initially orbits around it and then accumulates into a flattened disk. The gas stored in this disk gradually spirals inward and becomes compressed and heated as it nears the center. Ultimately reaching temperatures up to 20 million (12 million C)—some 2,000 times hotter than the sun's surface—the gas shines brightly in low-energy, or soft, X-rays.

For more than 40 years, however, observations show that black holes also produce considerable amounts of "hard" X-rays, light with energy 10 to hundreds of times greater than soft X-rays. This higher-energy light implies the presence of correspondingly hotter gas, with temperatures reaching billions of degrees.

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The new study bridges the gap between theory and observation, demonstrating that both hard and soft X-rays inevitably arise from gas spiraling toward a black hole.

Working with Noble and Julian Krolik, a professor at Johns Hopkins, Schnittman developed a process for modeling the inner region of a black hole's accretion disk, tracking the emission and movement of X-rays, and comparing the results to observations of real black holes.

Noble developed a computer simulation solving all of the equations governing the complex motion of inflowing gas and its associated magnetic fields near an accreting black hole. The rising temperature, density and speed of the infalling gas dramatically amplify magnetic fields threading through the disk, which then exert additional influence on the gas.

The result is a turbulent froth orbiting the black hole at speeds approaching the speed of light. The calculations simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein's theory of relativity.

Running on the Ranger supercomputer at the Texas Advanced Computing Center located at the University of Texas in Austin, Noble's simulation used 960 of Ranger's nearly 63,000 central processing units and took 27 days to complete.

Over the years, improved X-ray observations provided mounting evidence that hard X-rays originated in a hot, tenuous corona above the disk, a structure analogous to the hot corona that surrounds the sun.

"Astronomers also expected that the disk supported strong magnetic fields and hoped that these fields might bubble up out of it, creating the corona," Noble says. "But no one knew for sure if this really happened and, if it did, whether the X-rays produced would match what we observe."

Using the data generated by Noble's simulation, Schnittman and Krolik developed tools to track how X-rays were emitted, absorbed and scattered throughout both the accretion disk and the corona region. Combined, they demonstrate for the first time a direct connection between magnetic turbulence in the disk, the formation of a billion-degree corona, and the production of hard X-rays around an actively "feeding" black hole. Results from the study, "X-ray Spectra from Magnetohydrodynamic Simulations of Accreting Black Holes," were published in the June 1 issue of The Astrophysical Journal (ApJ, 769, 156).

In the corona, electrons and other particles move at appreciable fractions of the speed of light. When a low-energy X-ray from the disk travels through this region, it may collide with one of the fast-moving particles. The impact greatly increases the X-ray's energy through a process known as inverse Compton scattering.

"Black holes are truly exotic, with extraordinarily high temperatures, incredibly rapid motions and gravity exhibiting the full weirdness of general relativity," Krolik says. "But our calculations show we can understand a lot about them using only standard physics principles."

The study was based on a non-rotating black hole. The researchers are extending the results to spinning black holes, where rotation pulls the inner edge of the disk further inward and conditions become even more extreme. They also plan a detailed comparison of their results to the wealth of X-ray observations now archived by NASA and other institutions. Black holes are the densest objects known. Stellar-mass black holes form when massive stars run out of fuel and collapse, crushing up to 20 times the sun's mass into compact objects less than 75 miles (120 kilometers) wide.

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More information: arxiv.org/abs/1207.2693

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cantdrive85
1.2 / 5 (19) Jun 14, 2013
27 days of GIGO!
axemaster
5 / 5 (9) Jun 14, 2013
Wow, very excellent video, I learned a lot.
Gawad
4.2 / 5 (15) Jun 14, 2013
cantdrive85: a lifetime of GIGO.
LarryD
1 / 5 (2) Jun 14, 2013
Quite agree. I would have like some 'meat on the bones'.
alfie_null
3.9 / 5 (7) Jun 15, 2013
cantdrive85: a lifetime of GIGO.

As he is one of those crank science zealots, I'd take his comment accordingly.
SHREEKANT
1.2 / 5 (5) Jun 15, 2013
Congrats! to Susan for such a nice presentation of the observation.

It seems to be the inner view of black hole. The 'input' materials [as shown in video] is actually the 'output' material of the galaxy [in some cases may be of other galaxy too], but how?

Output material of Galaxy is also rotating outside the shown area, very fast.These materials enter the black hole from above the galactic plane. Its velocity go on increasing till it reach near the galactic core.

Its impact with core [containing/forming heavy element] releases ...... for for making the basic component of galaxy,like STARS,........But how?

Role of DA, DM & DE are very important. We have to understand how they interact with WM [white matter/baryon]- 'SUPERSYMMETRY'
Fleetfoot
5 / 5 (9) Jun 17, 2013
cantdrive85: a lifetime of GIGO.

As he is one of those crank science zealots, I'd take his comment accordingly.


He constantly preaches that scientists don't account for plasma, but here is research that "simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein's theory of relativity", precisely what he denies is considered. Of course it's decades ahead of the disproven crank stuff he worships so all he can do is go into denial.
Infinite Fractal Consciousness
not rated yet Jun 17, 2013
I heart photon rings now.
cantdrive85
1 / 5 (11) Jun 17, 2013
Where are the considerations for double layers? How does this circuitry connect to the rest of the galaxy? Does it? How does this simulation look? Does it match the filamentary and cellular aspects of the actual observations? The "crank stuff" is produced by those who cling to purely theoretical models of plasma behavior which has no support with laboratory results rather than the well supported particle and circuit models developed by Langmuir, Birkeland, Alfven, among others
Fleetfoot
5 / 5 (7) Jun 19, 2013
Where are the considerations for double layers?


The simulation matches observations without them hence there is no evidence for their formation under these conditions.

How does this circuitry connect to the rest of the galaxy? Does it?


No, there is a general inflow of neutral of matter but no electrical currents. Magnetic effects will be mostly short range.

How does this simulation look?


Excellent, it matches the observed x-ray spectrum very well.

Does it match the filamentary and cellular aspects of the actual observations?


The "actual observations" consist of x-ray spectra, the region modelled is a few AU seen from millions or billions of light years so impossible to image. As before, you are completely clueless about the scales involved by many orders of magnitude.

The "crank stuff" is produced by ...


You have just given an excellent demonstration of how to produce "crank stuff", simply ignore the science and repeat your mantras.
cantdrive85
1 / 5 (9) Jun 19, 2013
The simulation matches observations without them hence there is no evidence for their formation under these conditions.

Is this completely homogeneous plasma, there are no regions of differing density, chemical composition, or temperature? Oops, nope. We do know some things about plasma that some would consider facts. We do know that plasma invariably creates DL's in laboratory experiments, and we do know that these DL's can create radiation across the entire EM spectrum. What hasn't been confirmed by laboratory experimentation is this state of non-homogeneous plasma you describe that is devoid of DL's, this is a fact as well.
There are also "simulations" created by plasma physicists that create not only an accurate model of the core of a galaxy but also all of the required radiation of the core, jets, rotation, evolution, magnetic field, etc... of the ENTIRE galaxy in one simulation. According to you; Lab experimental data= crank: Untestable theoretical models= science. Swell.
Fleetfoot
5 / 5 (5) Jun 19, 2013
Is this completely homogeneous plasma, there are no regions of differing density, chemical composition, or temperature? Oops, nope.


Exactly, that's what they modelled.

We do know some things about plasma that some would consider facts. We do know that plasma invariably creates DL's in laboratory experiments,


Nope, we do know it sometime forms double layers but only in the right conditions, and we do know that lab experiments are nowhere near the conditions in an accretion disc.

and we do know that these DL's can create radiation across the entire EM spectrum.


Nope, read the article. Plasma can produce the soft x-rays but not the hard component, that's what is new here.

According to you; Lab experimental data= crank: Untestable theoretical models= science


Nope, models that match the spectrum = science, all talk and no models = EU crank, and clueless poster who can't tell the difference between hard and soft x-rays = you.
cantdrive85
1 / 5 (9) Jun 19, 2013
Exactly, that's what they modelled.


And there in lies the error, and the error in ALL astrophysical models. It's a theoretical construct which has no basis in reality. There is no observational data that supports this speculation of your homogeneous plasma. According to you, by that claim, the outer edges of the "accretion disc" are the exact same temps and density as at the cusp of the "black hole"? Here I thought it got faster, denser, and hotter as one approached the "event horizon".
Fleetfoot
5 / 5 (7) Jun 20, 2013
There is no observational data that supports this speculation ..


Read the article: ".. the team finds they can reproduce a range of important X-ray features long observed in active black holes."

and

"For more than 40 years, however, observations show that black holes also produce considerable amounts of 'hard' X-rays"

of your homogeneous plasma.


Read the article: "Our work traces the complex motions, particle interactions and turbulent magnetic fields ..". Nothing homogenous about that.

According to you, by that claim, the outer edges of the "accretion disc" are the exact same temps and density as at the cusp of the "black hole"?


Read the article: "The gas stored in this disk gradually spirals inward and becomes compressed and heated as it nears the center."

You are responding based on some fantasy version of the article that bears no resemblance to what is written or the work they have done.
cantdrive85
1 / 5 (9) Jun 20, 2013
Is this completely homogeneous plasma, there are no regions of differing density, chemical composition, or temperature? Oops, nope.


Exactly, that's what they modelled.


of your homogeneous plasma.


Read the article: "Our work traces the complex motions, particle interactions and turbulent magnetic fields ..". Nothing homogenous about that.


So which is it? Careful read my posts, I am claiming this to be non-homogeneous plasma (it seems you have changed your argument), and as such will have DL's as what is found in laboratory experiments and observation.

Now, it seems you are claiming (I'm confused) this to be non-homogeneous plasma that is devoid of DL's, contrary to lab observation, only supported by the MHD fluid models Alfven distinctly warned (during his Nobel speech no less) would be inadequate in describing any plasma phenomenon. There are DL models which explain these energies as well, I guess the observation supports the claims of both models.
Fleetfoot
5 / 5 (3) Jun 20, 2013
Is this completely homogeneous plasma, there are no regions of differing density, chemical composition, or temperature? Oops, nope.


Exactly, that's what they modelled.


of your homogeneous plasma.


Read the article: "Our work traces the complex motions, particle interactions and turbulent magnetic fields ..". Nothing homogenous about that.


So which is it? Careful read my posts, I am claiming this to be non-homogeneous plasma


And so was I and so was the article, you just ignored what was written and responded to something that was only in your imagination.

(it seems you have changed your argument),


Nope, you didn't listen.

and as such will have DL's as what is found in laboratory experiments and observation.


As I said before, the conditions are vastly different to anything ever created in a lab, with billion degree temperatures and material moving at half light speed, you have no way of knowing what sort of structures might form.
Fleetfoot
5 / 5 (4) Jun 20, 2013
.. only supported by the MHD fluid models Alfven distinctly warned (during his Nobel speech no less) would be inadequate in describing any plasma phenomenon.


However, the reality is that these models DO reproduce many of the key features of the observed spectra very well, he was wrong.

There are DL models which explain these energies as well,


Let's see a citation to such a model that reproduces the hard part of the spectrum as well as the soft then.

I guess the observation supports the claims of both models.


No, the new model gets closer than previous ones but is not yet fully accurate. You have not yet produced any evidence for the existence of any other model for there to be a "both".
cantdrive85
1 / 5 (9) Jun 21, 2013
you have no way of knowing what sort of structures might form.

Of course, and you do? Since I can't "know", I'll stick with the models that are supported by experimental results rather than purely theoretical models, that is until the evidence to the contrary is found.

Let's see a citation to such a model that reproduces the hard part of the spectrum as well as the soft then.


"Finally, it is interesting to note that radiative bursts from laboratory-produced plasma filaments occur over a broad spectral range, from the microwave region to the hard X-ray region."
'Synchrotron Radiation Spectrum of Galactic Sized Plasma Filaments'
http://www.plasma...ratt.pdf

It should be noted, those plasma filaments very definitely have DL's, unlike your simulation.

ValeriaT
1 / 5 (4) Jun 21, 2013
cantdrive85
1 / 5 (6) Jun 21, 2013
Use one nonsensical hypothetical construct to verify another?

What you've just said...
http://www.youtub...YJsQAhl0

At least my POV involves real phenomenon.

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