Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study shows how black holes get their ’kicks’

04.02.2004


RIT professor researches black-hole mergers



When black holes collide, look out! An enormous burst of gravitational radiation results as they violently merge into one massive black hole. The "kick" that occurs during the collision could knock the black hole clear out of its galaxy.

A new study describes the consequences of such an intergalactic collision.


Astrophysicist David Merritt, professor at Rochester Institute of Technology, and co-authors Milos Milosavljevic (Caltech), Marc Favata (Cornell University), Scott Hughes (Massachusetts Institute of Technology) and Daniel Holz (University of Chicago) explore the consequences of kicks induced by gravitational waves in their article, "Consequences of Gravitational Radiation Recoil," recently submitted to The Astrophysical Journal and posted online at http://arXiv.org/abs/astro-ph/0402057 after 8 p.m. on February 3, EST.

Virtually all galaxies are believed to contain supermassive black holes at their centers. According to current theory, galaxies grow through mergers with other galaxies. When two galaxies merge, their central black holes form a binary system and revolve around each other, eventually coalescing into a single black hole. The coalescence is driven by the emission of gravitational radiation, as predicted by Einstein’s theory of relativity.

Merritt and his colleagues determined how fast a black hole has to move to completely escape a galaxy’s gravitational field. They found that larger and brighter galaxies have stronger gravitational fields and would require a bigger kick to eject a black hole than the smaller systems. Likewise, less forceful impacts could jar the black hole out of its home at the center of a galaxy, only to later rebound back into position.

The kicks also call into question theories that would grow supermassive black holes from hierarchical mergers of smaller black holes, starting in the early universe. "The reason is that galaxies were smaller long ago, and the kicks would easily have removed the black holes from them," Merritt says.

According to Merritt and his co-authors, it’s more likely that supermassive black holes attained most of their mass through the accretion of gas and that mergers with other black holes only took place after the galaxies had reached roughly their current sizes.

"We know that supermassive black holes exist at the centers of giant galaxies like our own Milky Way," says Merritt. "But as far as we know, the smaller stellar systems do not have any black holes. Perhaps they used to, but they were kicked out."

The kick--a consequence of Einstein’s relativity equations--occurs because gravitational waves emitted during the final plunge are anisotropic, producing recoil. The effect is maximized when one black hole is appreciably larger than the other one. While astrophysicists have been aware of this phenomenon since the 1960s, until now no one has had the analytical tools necessary to accurately calculate the size of the effect. The first accurate calculation of the size of the kicks was reported in a companion paper by Favata, Hughes and Holz, which also appears online at http://arXiv.org.

Merritt notes that there is no clear observational evidence that the kicks have taken place. He contends that the best chance of finding direct evidence would be locating a black hole shortly after the kick occurs, perhaps in a galaxy that has recently undergone a merger with another galaxy.

"You would see an off-center black hole that hasn’t quite made its way back to the center yet," he says. "Even though the probability of observing this is low, now that astronomers know what to look for, I wouldn’t be surprised if someone finds one eventually."


###
NOTE: To talk to David Merritt, call 908-420-7942, or contact Susan Gawlowicz at 585-475-5061 or smguns@rit.edu.

Susan Gawlowicz | EurekAlert!
Further information:
http://www.rit.edu/
http://arXiv.org/abs/astro-ph/0402057

More articles from Physics and Astronomy:

nachricht Gamma rays will reach beyond the limits of light
23.10.2017 | Chalmers University of Technology

nachricht Creation of coherent states in molecules by incoherent electrons
23.10.2017 | Tata Institute of Fundamental Research

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: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Shrews shrink in winter and regrow in spring

24.10.2017 | Life Sciences

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>