Featured Research

from universities, journals, and other organizations

Old Math Model Aids Search For Gravitational Waves

Date:
June 23, 2007
Source:
University of Alabama Huntsville
Summary:
A new way of looking at a previously abandoned mathematical model might help astronomers study and accurately identify an exotic clan of gravitational waves.

A new way of looking at a previously abandoned mathematical model might help astronomers study and accurately identify an exotic clan of gravitational waves.

Related Articles


The waves in question come from small black holes or neutron stars in extremely elongated orbits around vastly larger black holes, says Dr. Lior Burko, an assistant physics professor at The University of Alabama in Huntsville (UAH). "This reopens an area of research that was closed several years ago."

The exotic gravitational waves are generated (as predicted by general relativity theory) when an orbiting compact object changes speed, accelerating as it approaches the larger black hole and slowing as it moves away.

"Just as an accelerating electric charge emits electromagnetic waves, so mass emits gravitational waves as the speed changes," Burko said.

The time-domain formulas that Burko and Khanna studied had been abandoned because they produced error rates of ten percent or more, compared to the more accurate frequency-domain formulae.

The problem, said Burko, is that the frequency-domain math doesn’t work especially well with objects in extremely elliptic orbits without burning up tons of computer time (and still getting large errors). And objects in elliptic or parabolic orbits are reasonably common in astronomy, as stars and small black holes wander or are pulled into orbits around massive black holes.

What to do, what to do?

The solution started with a change of perspective. To save computer time, early time-domain experiments looked at gravity waves inside a relatively small grid — only 100 times the radius of the large black hole.

Burko and Khanna, however, found that the larger you make the grid, the smaller your error bar shrinks. At 500 radii the error had dropped from ten percent to one percent. At 1,500 radii the error shrinks to 0.1 percent. The goal is an error of not more than 0.01 percent.

The tradeoff, of course, is that the larger grid means substantially more grid points and longer computing times. With 40 data points per radius, enlarging the grid from 100 to 1,500 radii increases the number of grid points from 320 million to 72 billion. And each grid point requires hundreds of calculations to simulate how gravity waves might form and evolve. That’s a lot of calculations, even for a super computer. A single run using the new model can take at least two weeks on a fast workstation.

The second big step had to do with how you calculate the size of the small black hole or neutron star. Mathematically, it is considered a point source compared to the much larger black hole. Making calculations based on a single point in the grid introduces new errors so astronomers use a Gaussian formula to simulate the gravity well of the orbiting object.Burko and Khanna found that how big you make that Gaussian spot also influences how big your error will be.

"Too small and you under sample," said Burko. "Too big and you start bringing in finite size effects. We found a sweet spot that would give you the least errors."

The goal is to accurately model what these special gravity waves look like when they leave their home galaxies. Astronomers use that data to calculate (and estimate) how those waves might look after they travel a few billion light years to Earth and various gravity wave detectors in the U.S. or in orbit following the Earth around the Sun. Knowing what to expect will help scientists recognize the "signal" from these gravitational waves.

The results of this research by Burko and Dr. Gaurav Khanna at the University of Massachusetts at Dartmouth are published on-line by EuroPhysics Letters.


Story Source:

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


Cite This Page:

University of Alabama Huntsville. "Old Math Model Aids Search For Gravitational Waves." ScienceDaily. ScienceDaily, 23 June 2007. <www.sciencedaily.com/releases/2007/06/070622190202.htm>.
University of Alabama Huntsville. (2007, June 23). Old Math Model Aids Search For Gravitational Waves. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2007/06/070622190202.htm
University of Alabama Huntsville. "Old Math Model Aids Search For Gravitational Waves." ScienceDaily. www.sciencedaily.com/releases/2007/06/070622190202.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
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