[occultist_throw]

BTW, this is also the basis of a story by Greg Egan. Diaspora. (Aside: I highly recommend Greg Egan's work, especially Diaspora)

The claim he makes in the fiction novel, is that a neutron star-neutron star collision event would be enough energy to sterilize 100 light year radius around the event. The one in the novel happens closer than 100ly.

http://www.gregegan.net/DIASPORA/DIASPORA.html