There's no reason to believe that a galactic merger would create a larger number of white dwarfs than normal. So the mystery endures.
Another possible explanation is that there are an inordinate number of white dwarfs in NGC 1316, which are the corpses of an extraordinary "baby boom" of stars in NGC 1316. If that's the case, a surge of white dwarf-triggered supernovae would be expected when all the "boomer generation" stars reach a similar age.
On the other hand, it could just be chance. Of the thousands of observable galaxies, odds are in favor of an occasional random clustering of supernovae in one galaxy, said John Nousek, a professor of astronomy and astrophysics at Pennsylvania State University.
"This sort of thing is more of a cosmic coincidence than a cosmic Rosetta stone," said Nousek. He and graduate student Peter Brown have been hard at work monitoring and trying to make sense of the double explosions.
"The exact mechanism is not well understood," said Gehrels. "This is a fairly hot topic."
