Alexei V. Filippenko

This astronomer from the University of California describes part of his reserch interests in this way:

"I am also interested in determining the physical properties of quasars and active galactic nuclei. The radiation emitted by a quasar is thought to be produced by matter being swallowed by a supermassive black hole, roughly a hundred million times more massive than the Sun, but the details are still murky. These photons ionize clouds of gas, and the resulting emission lines provide clues to the structure and nature of the central engine. I am especially fond of normal, nearby galaxies whose nuclei harbor activity similar to (but weaker than) that in classical active galaxies; at least some of these objects may have been luminous quasars in the distant past, but they are now accreting very little gas. I am part of a team that is finding supermassive black holes in the nuclei of nearby galaxies, some of which may be the remnants of long-dead quasars."

He could give clues on why two of the twenty seven highest energy particles detected by the Pierre Auger Observatory (PAO) come from the direction of the Centaurus A galaxy.

I recently asked Alex about the PAO discovery. He has this to say:

"I've not studied the Auger observations, but probably Cen A
has a very efficient collimation and acceleration mechanism for
the jet emerging from the active nucleus (supermassive black
hole)."