Our Sun is about 330,000 times the mass of Earth, yet it is dwarfed by the black holes that lurk at the centers of galaxies. A team of astronomers recently found the fastest-growing of this group: a 17-billion solar mass black hole in the distant universe, which is growing at the rate of one solar mass per day.
The black hole is actually a quasar, aka an actively feeding black hole at the center of a galaxy. When quasars accrete matter—which is to say, as their strong gravitational fields pull gas, dust, and other space debris towards them—they emit huge amounts of radiation, which is detectable to a range of Earth-based telescopes.
The quasar is named J0529-4351 (catchy, right?), and it sits at a redshift of 3.9, making the light from the quasar over 12 billion years old. The recent astronomical team observed the quasar at optical and near-infrared wavelengths using the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert. Their research describing the object is published this week in Nature Astronomy.
“We have discovered the fastest-growing black hole known to date,” said Christian Wolf, an astronomer at the Australian National University and the study’s lead author, in an ESO release, adding that the object is “the most luminous object in the known Universe.”
Quasars are among the most energetic objects in the cosmos, often outshining the stars in their galaxies. Last year, a different team of researchers found that about 65% of galaxies with quasars at their centers showed evidence that they had interacted or merged with other galaxies in the past—a potential sign that these immense galactic collisions are what might cause quasars in the first place.
Using this quasar’s brightness as a proxy for its accretion rate—since the brighter the quasar, the more mass is being pulled to the black hole—the team determined that the quasar is accreting approximately 413 solar masses per year, or roughly 1.13 Suns per day.
J0529-4351 was noted in sky surveys as early as 1980, but at the time astronomers didn’t realize it was a quasar. When objects appear brighter than any known quasars, models can construe them as nearby stars instead of faraway objects that are much, much more giant. J0529-4351 is a staggering 500 trillion times more luminous than our Sun, and the accretion disk which produces that light is seven light-years across.
“It is a surprise that it has remained unknown until today, when we already know about a million less impressive quasars. It has literally been staring us in the face until now,” said Christopher Onken, also an astronomer at ANU, in the release.
Overlooked no more, the object previously thought to be a star because it was so darn bright is actually a superlatively bright and much more complex object, much deeper in space. It may be better characterized by future telescopes, including the ESO’s own Extremely Large Telescope, the successor to the Very Large Telescope.
