Using data from the Sloan Digital Sky Survey, the motion of the satellite galaxies indicated the presence of a much larger, invisible mass. In other words, the larger galaxies are located at the center of giant concentrations of dark matter.
"This is a very important test of our understanding of how the universe works," said one of the researchers, Anatoly Klypin of New Mexico State University. "This is one of the most direct probes of the distribution of dark matter and the properties of dark matter."
The study further found that the gravitational pull of dark matter weakened at its periphery, a unique property not exhibited by bodies composed of ordinary matter.
"We detected a specific law -- the decline in dark-matter density toward the periphery," said Klypin. "The goal of our research is now to measure that law."
Dennis Zaritsky, an astronomer at University of Arizona at Tucson, first postulated dark matter in 1994. Zaritsky saw the excessive motion of satellite galaxies, indicating the presence of an invisible mass, but made no attempt to measure it.
"He was the first to see there was something wrong with motion," said Klypin. "Now (that) weve measured the law, we can reject other theories like MOND."
http://www.wired.com/news/technology/0,1282,58966,00.html
Thursday, May 22, 2003
Popular Posts
-
...These measures, based on the US Digital Millennium Copyright Act (DMCA) give far too much power to publishers, at the expense of individu...
-
William Gibson's latest novel, Spook Country is awesome. Not as frantic or kinetic as Pattern Recognition or All Tomorrow's Parti...
-
This is not bad. A mix of 70s rock and 80s punk with some good lyrics. Songs range from boring to excellent. Id give it a B+. http://www.ama...
-
The challenge of having the United States as a neighbour was one of the topics discussed Tuesday during a meeting with Mexican President Vic...
-
Here's my (edited) journal entry for this event dated 12/01/98: Wow. I just sessioned and started reading "The Tao of Physics"...
-
nother bottle of the doublewood -- arguably one of my favorite scotches. Balvenie just doesnt make a bad blend. A fab birthday gift from my ...
-
"The International Space Station will have ultra-sensitive clocks on board, and it is a good place to test the theory," said Dr. A...
-
Finally went out and picked up a Nintendo Wii. My god the thing is fun. Ridiculously, ludicrously fun. Hiyat and I had to tear ourselves...
-
This is from a 1932 episode of The Little Rascals . Man, I've had jobs like that. http://www.boingboing.net/2007/10/23/perpetually...
-
OK, if you have to go, this is the way to do it. Just like Spock in Star Trek II: The Wrath Of Khan. I'm serious. http://www.eter...