. 24/7 Space News .
TIME AND SPACE
Magnetic 'balding' of black holes saves general relativity prediction
by Thomas Sumner for SF News
New York NY (SPX) Oct 26, 2021

A simulation of the magnetic field lines (green) surrounding a black hole (left). As the field lines break and reconnect, pockets of plasma form (center of green circles). These plasma pockets launch inward toward the black hole or outward into space, draining energy from the magnetic field. A. Bransgrove et al./Physical Review Letters 2021

Black holes aren't what they eat. Einstein's general relativity predicts that no matter what a black hole consumes, its external properties depend only on its mass, rotation and electric charge. All other details about its diet disappear. Astrophysicists whimsically call this the no-hair conjecture. (Black holes, they say, "have no hair.")

There is a potentially hairy threat to the conjecture, though. Black holes can be born with a strong magnetic field or obtain one by munching on magnetized material. Such a field must quickly disappear for the no-hair conjecture to hold. But real black holes don't exist in isolation. They can be surrounded by plasma - gas so energized that electrons have detached from their atoms - that can sustain the magnetic field, potentially disproving the conjecture.

Using supercomputer simulations of a plasma-engulfed black hole, researchers from the Flatiron Institute's Center for Computational Astrophysics (CCA) in New York City, Columbia University and Princeton University found that the no-hair conjecture holds. The team reports its findings on July 27 in Physical Review Letters.

"The no-hair conjecture is a cornerstone of general relativity," says study co-author Bart Ripperda, a research fellow at the CCA and a postdoctoral fellow at Princeton. "If a black hole has a long-lived magnetic field, then the no-hair conjecture is violated. Luckily a solution came from plasma physics that saved the no-hair conjecture from being broken."

The team's simulations showed that the magnetic field lines around the black hole quickly break and reconnect, creating plasma-filled pockets that launch into space or fall into the black hole's maw. This process rapidly drains the magnetic field and could explain flares seen near supermassive black holes, the researchers report.

"Theorists didn't think of this because they usually put their black holes in a vacuum," Ripperda says. "But in real life, there's often plasma, and plasma can sustain and bring in magnetic fields. And that has to fit with your no-hair conjecture."

Ripperda co-authored the study with Columbia graduate student Ashley Bransgrove and CCA associate research scientist Sasha Philippov, who is also a visiting research scholar at Princeton.

A 2011 study on the problem suggested that the no-hair conjecture was in trouble. However, that study only looked at these systems at low resolution, and it treated plasma as a fluid. However, the plasma around a black hole is so diluted that particles rarely run into one another, so treating it as a fluid is an oversimplification.

In the new study, the researchers conducted high-resolution plasma physics simulations with a general-relativistic model of a black hole's magnetic field. In total, it took 10 million CPU hours to churn through all the calculations. "We couldn't have done these simulations without the Flatiron Institute's computational resources," Ripperda says.

The resulting simulations showed how the magnetic field around a black hole evolves. At first, the field extends in an arc from the black hole's north pole to its south pole. Then, interactions within the plasma cause the field to balloon outward. This opening up causes the field to split into individual magnetic field lines that radiate outward from the black hole.

The field lines alternate in direction, either toward or away from the event horizon. Nearby magnetic field lines connect, creating a braided pattern of field lines coming together and splitting apart. Between two such connection points, a gap exists that fills with plasma. The plasma is energized by the magnetic field, launching outward into space or inward into the black hole. As the process continues, the magnetic field loses energy and eventually withers away.

Critically, the process happens fast. The researchers found that the black hole depletes its magnetic field at a rate of 10 percent of the speed of light. "The fast reconnection saved the no-hair conjecture," Ripperda says.

The researchers propose that the mechanism powering observed flares from the supermassive black hole at the center of the Messier 87 galaxy could be explained by the balding process seen in the simulations. Initial comparisons between them look promising, they say, though a more robust assessment is needed. If they do indeed line up, energetic flares powered by magnetic reconnection at black hole event horizons may be a widespread phenomenon.

Research paper


Related Links
Simons Foundation
Understanding Time and Space


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


TIME AND SPACE
This is what it looks like when a black hole snacks on a star
Tucson AZ (SPX) Sep 20, 2021
While black holes and toddlers don't seem to have much in common, they are remarkably similar in one aspect: Both are messy eaters, generating ample evidence that a meal has taken place. But whereas one might leave behind droppings of pasta or splatters of yogurt, the other creates an aftermath of mind-boggling proportions. When a black hole gobbles up a star, it produces what astronomers call a "tidal disruption event." The shredding of the hapless star is accompanied by an outburst of radiation ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

TIME AND SPACE
Making space travel inclusive for all

Bezos' Blue Origin announces plans for private space station

Russia will fly four tourists into space in 2024

New far-out NASA 'travel' video: kayaking on Titan, skydiving on exoplanet

TIME AND SPACE
NASA seeks input to position mega-rocket for long-term exploration

Crew-3 astronauts launch to Space Station alongside microgravity research

NASA sending four astronauts to ISS on Sunday

Kuaizhou lifts off successfully, places satellite in orbit

TIME AND SPACE
You can help train NASA's rovers to better explore Mars

NASA Mars Rover and Helicopter models to go on national tour

Ingenuity Mars Helicopter Flight 14 Successful

China's Mars orbiter resumes communications with Earth

TIME AND SPACE
Chinese astronauts arrive at space station for longest mission

China's longest-yet crewed space mission impressive, expert says

Chinese astronaut bridges gender gap

Test conducted to verify spacecraft technology, FM says

TIME AND SPACE
NEOM Tech and Digital Holding Company and OneWeb sign $200m JV for satellite network

Verizon to use Amazon satellites for broadband Internet in rural areas

From Polar Bears to Polar Orbits

Conclusions from Satellite Constellations 2 Released

TIME AND SPACE
Bio-inspired autonomous materials

Getting NASA data to the ground with lasers

Emerging optics advances next-generation AR/VR displays

Carbon nanotubes could help electronics withstand outer space's harsh conditions

TIME AND SPACE
Breakthrough Listen releases analysis of previously detected signal

Could this be a planet in another galaxy?

Scientists measure the atmosphere of a planet 340 light-years away

The upside-down orbits of a multi-planetary system

TIME AND SPACE
Science results offer first 3D view of Jupiter's atmosphere

Jupiter's Great Red Spot is deeper than thought, shaped like lens

Using Charon-light Researchers Capture Pluto's Dark Side

Juno peers deep into Jupiter's colorful belts and zones









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.