Yes, it is as likely as that they arrive 15 years after one another.
Matt Strassler has joined Jester and me and noticed the intriguing excess of the \(3.5\keV\) X-ray line in the galaxy clusters that resembles a dark matter particle of a sort (sterile neutrino, axino, axion, moduli, we may ultimately learn).
But here I want to focus on a cute sentence that Matt wrote in parentheses. After he noticed another, possibly decreasingly convincing, gamma-ray line near \(130\GeV\) in the Fermi data, he wrote:
You can invent types of dark matter that would give you both signals – but it would take a small miracle for two signals of the same dark matter particles to show up in the same year.It's an amusing argument against the possibility that "both signals are real dark matter" but is the argument valid? I am sometimes making similar arguments (or at least tempted to do so), too. So the logic may deserve a few words.