A QUAsi-StellAR radio source (or Quasar) is a very energetic object that looks like a star, but is actually a very distant galaxy with a very bright galactic core. They are probably the brightest objects in the universe, and many times brighter than normal galaxies.
Astronomers think that quasars are compact regions surrounding supermassive black holes found at the centre of galaxies. The vast power generated by quasars comes from high-energy collisions within the accretion disks swirling around the black hole.
In other words, the black hole is so big that it's ripping apart and consuming nearby stars, and in doing so, is generating a continuous string of massive explosions that can be seen across the universe.