Chandra radiograph shows Cassiopeia A - the youngest supernova remnant in the Milky Way
Recent findings from the Rochester Institute of Technology hint that massive black holes reside on the edges of spiral galaxies. These forgotten regions will now become new places to search for gravitational waves created in the collision of massive bodies.
The study returns to massive black holes, analyzing their visible supernova precursors with collapsing nuclei. The slow decline of these massive stars creates vivid signatures in the EM spectrum before the stellar evolution ends in a black hole.
Using data from a review of the Lick Observatory, the researchers compared the speed of supernovae in outer spiral galaxies with known dwarf / satellite galaxies. They were able to detect comparable numbers for typical spiral margins and typical dwarf galaxies — roughly two blown-up supernovae over a thousand years. Low levels of elements heavier than hydrogen and helium found in dwarf / satellite galaxies create favorable conditions for the formation of massive black holes and double pairs. Such a galactic environment on the outer disks of spiral galaxies also creates probable prosperous territories for massive black holes.
If these supernovae with collapse are the precursors of the double black holes found by LIGO, then scientists will get a reliable method for identifying host galaxies of LIGO sources. Such black holes have an EM-analogue at an earlier stage of existence, so you can accurately determine their location in the sky and watch massive black holes.