Featured Research

from universities, journals, and other organizations

Simulations Reveal Surprising News About Black Holes

Date:
March 14, 2005
Source:
Johns Hopkins University
Summary:
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.

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

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.

###

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


Story Source:

The above story is based on materials provided by Johns Hopkins University. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins University. "Simulations Reveal Surprising News About Black Holes." ScienceDaily. ScienceDaily, 14 March 2005. <www.sciencedaily.com/releases/2005/03/050310180926.htm>.
Johns Hopkins University. (2005, March 14). Simulations Reveal Surprising News About Black Holes. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2005/03/050310180926.htm
Johns Hopkins University. "Simulations Reveal Surprising News About Black Holes." ScienceDaily. www.sciencedaily.com/releases/2005/03/050310180926.htm (accessed October 22, 2014).

Share This



More Space & Time News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) — A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) — Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com
Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Newsy (Oct. 17, 2014) — The smallest of Saturn's main moons, Mimas, wobbles as it orbits. Research reveals it might be due to a global ocean underneath its icy surface. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins