Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Powerful magnetic fields challenge black holes' pull

05.06.2014

Black holes are thought to dominate their surroundings by their extremely powerful gravitational pull.

However, other forces which are usually considered to be weaker are also at work near these objects. These include forces exerted by the pressure of the in-falling hot gas and magnetic forces.


A computer simulation of gas (in yellow) falling into a black hole (too small to be seen). Twin jets are also shown with magnetic field lines. Credit: Alexander Tchekhovskoy (LBNL)

In a surprising twist, a team of astronomers at the Max Planck Institute for Radio Astronomy (MPIfR) and Lawrence Berkeley National Laboratory (LBNL) has found that in fact magnetic forces can be as strong as gravity near supermassive black holes. These findings are published in this week's issue of Nature.

Some black holes that are voraciously consuming interstellar gas also expel some of it in twin narrow outflows, or jets. This study focused on those supermassive black holes at the centers of galaxies that have observed radio-emitting jets.

"We realized that the radio emission from a black hole's jets can be used to measure the magnetic field strength near the black hole itself", says the study's lead-author, Mohammad Zamaninasab (formerly at the MPIfR and supported by a grant from Deutsche Forschungsgemeinschaft, DFG). "Our real aha experience came when we compared our magnetic force measurements to the force of gravity near black holes, and found them to be comparable”, he continues.

On a purely theoretical level, the possibility that magnetic fields may be as strong as gravity near black holes has been studied by state-of-the-art computer simulations. “When the in-falling gas carries enough magnetic field in our simulations, then the magnetic field near the black hole gets stronger until it balances gravity”, explains Alexander Tchekhovskoy (LBNL), a co-author of the study. “This fundamentally changes the behavior of the gas near the black hole.”

Surprisingly, the magnetic field strength around these exotic objects is comparable to the magnetic field produced in something more familiar: a magnetic resonance imaging (MRI) machine that you can find in your local hospital. Both supermassive black holes and MRI machines produce magnetic fields that are roughly 10 000 times stronger than the Earth's surface magnetic field, which is what guides an ordinary compass.

The measurements of the magnetic field strength near the black hole were based on mapping what fraction of the radio emission is absorbed at different locations near the base of the jet. “Such observations existed for an order of hundred sources from earlier work of several international re-search teams using the Very Long Baseline Array, a network of radio telescopes spread across the United States”, says co-author Tuomas Savolainen from MPIfR. “A large fraction of these measurements had just relatively recently become available thanks to a large observing program called MOJAVE, which monitors several hundred jets launched by supermassive black holes.”

The strength of the magnetic field near the black hole horizon also controls how powerful its jets are and, therefore, how luminous they appear at radio wavelengths according to current theories that treat black holes as a sort of spinning magnet. Thus, it is possible that the bright radio jets emanate from those black hole systems that have magnetic fields as strong as gravity.

These results may lead to changes in how to interpret black hole observations. “If our ideas hold up to further scrutiny, then astronomers' expectations for how to measure black hole properties would need to be changed.” concludes Eric Clausen-Brown, also from MPIfR. “Our study also changes how powerful we expect black hole jets can be, and since these jets can impact their own galaxies and beyond, we may need to rethink how much of an environmental impact black holes can have.”

Original Paper:

Dynamically-important magnetic fields near accreting supermassive black holes, by M. Zamaninasab, E. Clausen-Brown, T. Savolainen, A. Tchekhovskoy, published in: 2014, Nature. DOI: 10.1038/nature13399
http://www.nature.com/nature/journal/v510/n7503/full/nature13399.html
(after the embargo expires).

Contact:

Dr. Mohammad Zamaninasab
Fon: +49(0)176 64972814
E-mail: m.zamaninasab@gmail.com

Dr. Eric Clausen-Brown
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-473
E-mail: clausenbrown@mpifr-bonn.mpg.de

Dr. Tuomas Savolainen
Max-Planck-Institut für Radioastronomie
Fon: +49(0)228-525-473
E-Mail: tsavolainen@mpifr-bonn.mpg.de

Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-399
E-mail: njunkes@mpifr-bonn.mpg.de

Weitere Informationen:

http://www.mpifr-bonn.mpg.de/pressreleases/2014/6

Norbert Junkes | Max-Planck-Institut

Further reports about: LBNL MPIfR MRI Max-Planck-Institut Radioastronomie Savolainen galaxies gravity measurements

More articles from Physics and Astronomy:

nachricht Streamlining accelerated computing for industry
24.08.2016 | DOE/Oak Ridge National Laboratory

nachricht Lehigh engineer discovers a high-speed nano-avalanche
24.08.2016 | Lehigh University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Streamlining accelerated computing for industry

PyFR code combines high accuracy with flexibility to resolve unsteady turbulence problems

Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...

Im Focus: X-ray optics on a chip

Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.

In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...

Im Focus: Piggyback battery for microchips: TU Graz researchers develop new battery concept

Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.

Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...

Im Focus: UCI physicists confirm possible discovery of fifth force of nature

Light particle could be key to understanding dark matter in universe

Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...

Im Focus: Wi-fi from lasers

White light from lasers demonstrates data speeds of up to 2 GB/s

A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The energy transition is not possible without Geotechnics

25.08.2016 | Event News

New Ideas for the Shipping Industry

24.08.2016 | Event News

A week of excellence: 22 of the world’s best computer scientists and mathematicians in Heidelberg

12.08.2016 | Event News

 
Latest News

Hans Clevers to receive the Körber Prize 2016

25.08.2016 | Awards Funding

An effective and low-cost solution for storing solar energy

25.08.2016 | Power and Electrical Engineering

PRB projects world population rising 33 percent by 2050 to nearly 10 billion

25.08.2016 | Social Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>