All galaxies have a supermassive black hole at their center, a region that absorbs all surrounding matter, releasing enormous amounts of energy in the form of visible light and radio frequencies. They are quasars, the brightest and hottest objects in the universe. An international team has just discovered the brightest, most luminous quasar ever observed.
The details of the discovery appear this Monday in a paper published in the journal Nature Astronomy. Quasars get their energy from supermassive black holes. This record-breaking quasar’s black hole is so voracious that it is increasing its mass by the equivalent of a sun per day, making it the fastest-growing black hole discovered to date.
In addition, quasars emit large amounts of light that are visible even from Earth by collecting matter from their surroundings. For this reason, the newly discovered quasar, which is located in the fastest growing black hole to date, “with a mass of 17 billion suns and which barely eats more than one sun per day,” is also “the best-known universe.” says Christian Wolf, astronomer at the Australian National University (ANU) and lead author of the study. Astronomers made this discovery using the European Southern Observatory’s (ESO) Very Large Telescope (VLT).
According to their calculations, J0529-4351, as this quasar is called, is so far away that its light took more than 12 billion years to reach Earth. The material attracted to this disk-shaped black hole radiates so much energy that J0529-4351 is more than 500 billion times more luminous than the Sun. “All this light comes from a hot accretion disk seven light-years across.” That’s about 15,000 times the distance from the Sun to Neptune’s orbit. “It must be the largest accretion disk in the universe,” concludes Samuel Lai, ANU doctoral student and co-author of the study.
Hidden in plain sight
But for the authors, that’s the most surprising thing This record-breaking quasar was hiding in plain sight. “It is a surprise that it has not been discovered to date, even though we already know about a million less impressive quasars. It has literally been staring us in the face so far,” says Christopher Onken, an astronomer at ANU and co-author of the study.
And although this object appeared in images from ESO’s Schmidt Southern Sky Survey in 1980, it was only recognized as a quasar decades later, Onken admits. Searching for quasars requires precise observation data from large areas of the sky. However, such an amount of information can only be analyzed using machine learning models that perform the search and distinguish quasars from other celestial objects. However, because these models are trained on existing data, they can make mistakes and classify discoveries as objects similar to those already known.
So if a new quasar is more luminous than any previously observed, the program could reject it and classify it as a star not too far from Earth. An automated analysis of data from the European Space Agency’s Gaia satellite found that J0529-4351 is too bright to be a quasar, suggesting it is a star. Researchers identified it as a distant quasar last year based on observations with the 2.3-meter ANU telescope at the Siding Spring Observatory in Australia.
However, finding out that it was the most luminous quasar ever observed required a larger telescope and more precise measurements. The X-Shooter spectrograph installed on ESO’s VLT in Chile’s Atacama Desert provided the crucial data. The discovery and study of distant supermassive black holes could shed light on some of the mysteries of the early universe, including how they and their host galaxies formed and evolved.