Simulations Reveal Surprising News About Black Holes

Johns Hopkins University via Science Daily ^ | 3/14/2005 | Lisa De Nike

[Excuse_My_Bellicosity]

For more than 30 years, astrophysicists have believed that black holes can swallow nearby matter and release a tremendous amount of energy as a result. Until recently, however, the mechanisms that bring matter close to black holes have been poorly understood, leaving researchers puzzled about many of the details of the process.

Now, however, computer simulations of black holes developed by researchers, including two at The Johns Hopkins University, are answering some of those questions and challenging many commonly held assumptions about the nature of this enigmatic phenomenon.

"Only recently have members of the research team -- John Hawley and Jean-Pierre De Villiers, both of the University of Virginia -- created a computer program powerful enough to track all the elements of accretion onto black holes, from turbulence and magnetic fields to relativistic gravity," said Julian Krolik, a professor in the Henry A. Rowland Department of Physics and Astronomy at Johns Hopkins and co-leader of the research team. "These programs are opening a new window on the complicated story of how matter falls into black holes, revealing for the first time how tangled magnetic fields and Einsteinian gravity combine to squeeze out a last burst of energy from matter doomed to infinite imprisonment in a black hole."

Close to the black hole's outer edge, where the Newtonian description of gravity breaks down, ordinary orbits are no longer possible. At that point -- or so it has been imagined for the past three decades -- matter plunges quickly, smoothly and quietly into the black hole. In the end, according to the prevailing picture, the black hole -- except for exerting its gravitational pull -- is a passive recipient of mass donations.

The team's first realistic calculations of matter falling into black holes have strongly contradicted many of these expectations. They show, for instance, that life in the vicinity of a black hole is anything but calm and quiet. Instead, the relativistic effects that force matter to plunge inward magnify random motions within the fluid to create violent disturbances in density, velocity and magnetic field strength, driving waves of matter and magnetic field to and fro. This violence can have observable consequences, according to research team co-leader Hawley.

"Just like any fluid that has been stirred into turbulence, matter immediately outside the edge of the black hole is heated. This extra heat makes additional light that astronomers on Earth can see," Hawley said. "One of the hallmarks of black holes is that their light output varies. Although this has been known for more than 30 years, it has not been possible to study the origins of these variations until now. The violent variations in heating -- now seen to be a natural byproduct of magnetic forces near the black hole -- offer a natural explanation for black holes' ever-changing brightness."

One of the most striking properties of a black hole is its ability to expel jets at close to the speed of light. While it has long been expected that magnetic fields are crucial to this process, the latest simulations show for the first time how a field can be expelled from the accreting gas to create such a jet.

Perhaps the most surprising result of the team's new computer simulations is that the magnetic fields brought near a rotating black hole also couple the hole's spin to matter orbiting farther out, in the same way that a car's transmission connects its rotating motor to the axle. Says Krolik, "If a black hole is born spinning extremely rapidly, its 'drive train' can be so powerful that its capture of additional mass causes its rotation to slow down. Accretion of mass would then act as a 'governor,' enforcing a cosmic speed limit on black hole spins."

According to Krolik, that "governor" may have strong implications for many of the most striking properties of black holes. It is widely thought, for example, that the strength of a black hole's jet is related to its spin, so a "spin speed limit" might determine a characteristic strength for the jets, Krolik said.

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Funded by the National Science Foundation, this research is being published in a series of four papers in The Astrophysical Journal. (De Villiers et al 2003, ApJ 599, 1238; Hirose et al. 2004, ApJ 606, 1083; De Villiers et al. ApJ 620, 879; Krolik et al. April 2005 ApJ in press.) The simulations were performed at the NSF-supported San Diego Supercomputer Center.

The research team also included Shigenobu Hirose, also of Johns Hopkins.

To view video animations of the computer simulation, as well as color stills of twisting magnetic fields, go to: http://www.jhu.edu/news_info/news/audio-video/blackholes.html

Editor's Note: The original news release can be found here: http://www.jhu.edu/news_info/news/home05/mar05/blckhole.html.

[Excuse_My_Bellicosity]

Computer simulations of how black holes swallow
matter show surprising violence and turbulence.
(Image Credit: Johns Hopkins University)

[meandog]

...matter plunges quickly, smoothly and quietly into the black hole. In the end, according to the prevailing picture, the black hole -- except for exerting its gravitational pull -- is a passive recipient of mass donations.

Finally! Someone has finally explained the success of (black hole) Rev. Jesse Jackson in gaining mass donations from the corporate community!

[ELS]

Very cool.

[Excuse_My_Bellicosity]

Close-up simulation here: http://www.jhu.edu/news_info/realmedia/hole1.mpg

Entire simulation here: http://www.jhu.edu/news_info/realmedia/hole2.mpg

Electromagnetic energy simulation here: http://www.astro.virginia.edu/VITA/jetmovie.mpg

[Revelation 911]

isnt "Hole" that Courtney Love band ?

huhuhhuhhuuh

[meandog]

I would assume that black holes would be a rather crushing experience (pun intended) rather than an imaginary passage to a parallel universe...the science is very intriguing. I understand that black holes do hold some promise as an engine for future space vehicles (tapping upon their massive attraction properties).

[longshadow]

Good article;

DEPLOY THE PING LIST!

[PatrickHenry]

Science Ping!

An elite subset of the Evolution list.

See list's description in my freeper homepage. Then FReepmail to be added/dropped.

[Excuse_My_Bellicosity]

Thanks. Post #4 has links to video simulations, too.

[VadeRetro]

Says Krolik, "If a black hole is born spinning extremely rapidly, its 'drive train' can be so powerful that its capture of additional mass causes its rotation to slow down. Accretion of mass would then act as a 'governor,' enforcing a cosmic speed limit on black hole spins."

This reminds me of the "Stump the Dummies" question about how the solar system could have formed with so much of its angular momentum concentrated in the outer planets and so little in the Sun. The answer is that the Sun slowed its rotation while pushing magnetically on the magnetic fields of the planets, transferring its momentum to them.

[roaddog727]

Chaos theroy applied to black holes.

Absolutely.

[js1138]

This reminds me of the "Stump the Dummies" question about how the solar system could have formed with so much of its angular momentum concentrated in the outer planets and so little in the Sun. The answer is that the Sun slowed its rotation while pushing magnetically on the magnetic fields of the planets, transferring its momentum to them.

Or why the moon is falling away from the earth.

[AntiGuv]

I would assume that black holes would be a rather crushing experience ... rather than an imaginary passage to a parallel universe.

Why not both? The black hole could both crush whatever falls in and also spew it out into a parallel universe. In any event, you'd probably be much better off using a wormhole for interuniversal travel..

[zeugma]

bump for later enjoyment.

[Alamo-Girl]

Thanks for the ping!

[pharmamom]

PH: Maybe you can answer this question for me. (My autistic son is WAY into black holes.) The simulations of a black hole always make them look like they are flat. The accretion disk is 2-dimensional. The old rubber sheet explanation makes the event horizon look like a plane until the object plunges into the black hole. Wouldn't black holes be spherical? A singularity would attract things from all "sides"--meaning that no matter how you approached the black hole, you would encounter an event horizon. It is hard to visualize, but it sure wouldn't look like a bathroom drain.

[PatrickHenry]

Definitely spherical.

[pharmamom]

Thanks. I'm not as dumb as I thought I was.

[jb6]

What I don't understand is this: matter can not be destroyed nor created. So, does a black hole ever reach capacity? You can only condense atoms so far and under that kind of pressure God knows what radioactive elements they would form, but still, they would continue to build up. So: 1. does it reach capacity? 2. is there a solid, super dense center of a black hole. 3. Does a black hole ever die or is the universe going to be eventually consumed by black holes? 4. Is there any evidence that it folds time/space, that the event horizon is an infinity margin?

[Fred Hayek]

Even if the matter does wind up at another location, it would be fried by the radiation from other material being attracted, heated by the turbulance to the point of emmitting x-ray's as the dominant form of black-body radiation. In addition, even before the Newton limit is reached, the differential gravitational forces would rent it asunder. So if anything does emerge on "the other side" (this assumes of course that anything might), it would likely be in the form of a stream of subatomic particles.