Two black holes may reside in same star cluster

Science : Widely held theory says that two black holes cannot exist for long in close proximity to each other—either the two will merge or one of them will be ejected from the pair. However, radio spectra observations of globular cluster M22 may show two stellar-mass black holes present in the system. Jay Strader of Michigan State University and his colleagues used the Very Large Array to obtain the spectra and believe they have ruled out other possible sources. If they are correct, it would be the first time stellar-mass black holes have been detected via radio-wave emission and the first time that black holes have been found in star clusters in the Milky Way. However, the lack of the detection of any x-ray emissions may challenge the possibility that either object is a black hole. Strader hopes that further observations using Hubble and other telescopes will confirm his team’s findings.