Latest Issue of Science News


Energy-Saving Space Engines: Black holes can be green

Some seemingly quiet black holes are actually efficient engines that emit jets of high-energy particles. This finding, from the first study to directly measure the efficiency of black holes, offers a hint as to why the universe isn't more crowded with stars.

All black holes swallow matter and spit out energy. Their gravitational pull traps clouds of hot, X-ray–emitting gas, and the black holes spew radiation or jets of high-energy particles.

Note: To comment, Science News subscribing members must now establish a separate login relationship with Disqus. Click the Disqus icon below, enter your e-mail and click “forgot password” to reset your password. You may also log into Disqus using Facebook, Twitter or Google.

This article is available only to subscribing members. Join SSP today or Log in.