Possibly a rogue stellar black hole is wandering within 3,000 light years.

It still needs to be confirmed that there is a specific direction or two that the rays are sourced. Also it needs to be checked if there is peculiar or proper motion associated with the source(s). Also, if a rogue black hole, whether the particles derive from a jet, as in a microquasar, or whether nearby cosmic rays that pass by its gravity well that already have hyperbolic velocity get a Delta V assist from a flyby anomaly to stand out from background levels.

Once a potential location is plotted, then astronomers can try to confirm a nearby rogue black hole by looking for independent clues such as microlensing and Shapiro time delays if it is close enough to show proper motion.

While I do not find this scenario very probable, I can't rule it out either.