A very bright quasar, the brightest object ever observed in the Universe, was spotted by astronomers using the European Southern Observatory’s (ESO) Very Large Telescope (VLT). The research is published today in the journal Nature Astronomy.

Quasars are the luminous cores of distant galaxies and are powered by supermassive black holes. The black holes that power quasars collect matter from their surroundings in a process so energetic that they emit enormous amounts of light.

In this quasar named J0529-4351 the black hole has a mass of 17 billion Suns and is increasing in mass at the equivalent of one Sun per day making it the fastest growing black hole to date! It is so far from Earth that its light took over twelve billion years to reach us.

J0529-4351 emits so much energy that it is more than 500 trillion times brighter than the Sun. It is remarkable that although it was in… common sight, it remained unknown until today and this is because finding quasars requires accurate observational data from large areas of the sky. The resulting datasets are so large that researchers often use machine learning models to analyze them and distinguish quasars from other celestial objects. However, these models are trained on existing data, which limits potential candidates to objects similar to those already known, so if a new quasar is brighter than any previously observed, the program may reject it and classified as a star.

Researchers identified J0529-4351 as a distant quasar last year using observations with the Australian National University’s 2.3-meter telescope, but the discovery that it is the brightest quasar ever observed required a larger telescope and measurements from a more accurate instrument. The X-shooter spectrograph on ESO’s VLT provided the crucial data.

More data on the fastest-growing black hole ever observed will be provided by the GRAVITY+ upgrade to the VLT’s interferometer, designed to precisely measure the mass of black holes. In addition, ESO’s Extremely Large Telescope (ELT), also under construction in Chile’s Atacama Desert, will make the detection and characterization of such elusive objects even more possible.