ADVERTISEMENT
See Inside November 2007

Dark Riddles

Behavior of galaxy cluster may shift thinking about gravity

Dark matter, the substance no one has ever seen, continues to baffle cosmologists. New observations of the distribution of dark matter in a distant cluster of galaxies may even force scientists to propose a fifth force of nature—or to rewrite the basics of Newtonian gravity. Little wonder that many researchers hope that the unsettling result will turn out to be an observational fluke.

Giant clusters of galaxies consist of two observable components. The galaxies themselves can be seen with large optical telescopes. The hot, tenuous gas in between the galaxies can be spied and mapped by x-ray satellites such as NASA’s Chandra X-ray Observatory. But according to current wisdom, a galaxy cluster may have a third, invisible component: mysterious dark matter that pulls in the atoms from which stars and galaxies form. Dark matter can be charted only by the subtle way its gravity slightly bends light, altering the shapes of faint galaxies in the distant background. The ability to detect such “weak lensing” has seen major improvements during the past decade.

This is only a preview. Get the rest of this article now!

Select an option below:

Customer Sign In

*You must have purchased this issue or have a qualifying subscription to access this content


It has been identified that the institution you are trying to access this article from has institutional site license access to Scientific American on nature.com.
Click here to access this article in its entirety through site license access.

Rights & Permissions
Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American Holiday Sale

Give a Gift &
Get a Gift - Free!

Give a 1 year subscription as low as $14.99

Subscribe Now! >

X

Email this Article

X