News Astronomy Cohabiting black holes challenge theory Radio observation puzzles astronomers Share this:FacebookTwitterPocketRedditPrint By Nadia Drake October 3, 2012 at 1:26 pm This article is only available to Science News subscribers. Subscribers, enter your e-mail address to access our archives. Client key* E-mail* Log in Not a subscriber? Science News is a nonprofit. Support us by subscribing now. Subscribe