Astronomers have found a radio galaxy whose central black hole appears to have launched powerful jets on four separate occasions, switching on, shutting down and restarting repeatedly.

The galaxy, J023721.13-010528.5, was studied with the upgraded Giant Metrewave Radio Telescope, MeerKAT and the Very Large Array. Observations reveal four pairs of radio structures arranged symmetrically around the galaxy, stretching about 3.9 million light-years across.

A statistical test found the “four separate episodes” explanation about 3 million times more likely than random jet knots, the team wrote in their arXiv paper. It is the first known “quadruple-double” radio galaxy.

The jet axes also rotate progressively outward, suggesting the black hole’s spin axis is slowly wobbling. The source forms an enormous S shape, the second-largest known.

Researchers say giant S-shaped radio galaxies could be the best hunting ground for more such rare multi-episode systems.