Galaxies shine light on dark matter.More than 80 years ago, Albert Einstein made an astounding a·stound tr.v. a·stound·ed, a·stound·ing, a·stounds To astonish and bewilder. See Synonyms at surprise. [From Middle English astoned, past participle of astonen, assertion: Gravity bends light. A clump of matter can act like an irregularly shaped piece of glass, altering the path of light rays from an object that lies behind it and creating a distorted image. The material doing the distorting, an effect known as gravitational lensing, needn't be visible stars or galaxies. The unseen material known as dark matter, which astronomers believe pervades space and weighs 10 times as much as all the visible stuff, should also bend light (SN: 1/8/00, p. 30). Four teams of astronomers have now independently found signs of lensing due to dark matter, providing fresh evidence for the existence and distribution of this massive but unseen component of the cosmos. Gathering the evidence required years of study. Dark matter typically elongates the image of a perfectly round galaxy by a tiny amount. Because no galaxy is exactly round, however, images of a single object can't reveal whether it's been distorted. Images of many galaxies lying behind a single dark-matter clump will all suffer elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. along the same direction, allowing astronomers to tease out the lensing. David M. Wittman of Bell Laboratories in Murray Hill Murray Hill may refer to one of the following places:
Three other groups have posted similar findings on the Internet. Their reports are numbers 0003338, 0003008, and 0002500 at http://xxx.lanl.gov/abs/astro-ph. These studies "could be the first shots of a revolution in our ability to measure dark matter," comments Max Tegmark Max Tegmark (born 5 May 1967) is a Swedish-American cosmologist. Tegmark is an Associate Professor at the Massachusetts Institute of Technology where he belongs to the scientific directorate of the Foundational Questions Institute. of the University of Pennsylvania (body, education) University of Pennsylvania - The home of ENIAC and Machiavelli. http://upenn.edu/. Address: Philadelphia, PA, USA. in Philadelphia in the same issue of NATURE. Ultimately, he says, such observations will produce dark-matter maps of the entire sky. |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion