The Flickering Light of Dual Quasars

This simulation shows the brilliant, flickering light from a pair of quasars. Astronomers in a recent study deduced that the blinking light is a telltale sign of the presence of two quasars and not a single object.

Quasars reside at the hearts of galaxies. They are ignited by monster black holes voraciously feeding on infalling matter, unleashing a torrent of radiation. A quasar’s light fluctuates in brightness based on how much material its black hole is gobbling up at the time.

This quasar pair is pouring out light because their galaxies are in the process of merging, which provides plenty of fuel for their hungry black holes. The quasars appear close together because they, too, are in the process of merging, along with their galaxies.

The quasars were first identified by the European Space Agency’s Gaia spacecraft, which measures small changes in the brightness of stars. The quasar pair is too far away for Gaia to resolve. Instead, the pair looks like a single bright object. However, Gaia also measured an apparent “jiggle” in the light. The “jiggle” is a signal of the independent flickering light between two separate quasars, similar to a pair of alternating lights on a railroad-crossing signal. The Hubble Space Telescope is sharp enough to resolve the quasar pair, which astronomers had suspected from the Gaia data.

Credit: NASA, ESA, and J. Olmsted (STScI)