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Illustration of Quasar J0529-4351: the most luminous celestial object of its kind to date

Photo: ESO / M. Kornmesser / EPA

Twelve billion light-years away lies the quasar, which has now set a double record: it is the most luminous celestial object of its kind to date and the fastest growing. Its central black hole absorbs the mass of a sun every day - in total it already contains 17 billion solar masses, reports an international research team in the journal "Nature Astronomy".

“Astronomers have already been able to detect and catalog over a million quasars using new discovery methods,” explains the group led by Christian Wolf from the Australian National University in Canberra. “Surprisingly, it is the brightest such objects that are the most difficult to find.”

Astronomers refer to quasars as bright radiation sources in the center of galaxies that are powered by supermassive black holes.

500 trillion times more energy than our sun

With their gravity, the black holes attract matter from the environment, which accumulates in a rapidly rotating disk, is heated by friction and therefore shines brightly. In the quasar discovered by Wolf and his team, this accretion disk radiates 500 trillion times more energy than our sun. The disk has a diameter of seven light-years, making it the largest accretion disk known to date, according to the researchers.

In order to detect quasars in the immense amount of data that large telescopes on Earth and in space produce today, astronomers are increasingly relying on artificial intelligence. But there is a problem: the systems can only be trained using objects that are already known. If a quasar differs greatly from objects that have already been discovered, the algorithms will sometimes sort it out.

That's exactly what happened with Quasar J0529-4351. The celestial object first appeared as a star in a 1980 survey of the sky by the European Southern Observatory. Last year, a machine analysis of data from the Gaia astronomy satellite, which records almost two billion celestial objects, classified J0529-4351 as a star in our Milky Way with a probability of 99.98 percent.

“A human astronomer would have recognized that it was a quasar with just one look at the spectrum of J0529-4351 provided by Gaia,” said Wolf and his team. However, experts need too much time to inspect data from billions of celestial objects.

In the case of J0529-4351, only additional observations - including with a 2.3 meter telescope in Australia - revealed the true nature of the object. Investigations with the European Southern Observatory's Very Large Telescope finally confirmed the suspicion that it was an unusual, record-breaking quasar.

The data showed that the object's light takes 12 billion years to reach Earth. This enabled the team to calculate how much energy the quasar actually radiates in order to still appear in the sky like a Milky Way star at this gigantic distance.

With the help of quasars like J0529-4351, astronomers hope to better understand the formation and evolution of galaxies in the young cosmos. And in particular to answer the question of how such large black holes could have formed so quickly after the Big Bang.