The brightest object ever observed is so far outside the range of its counterparts that the astronomers who discovered it believe it will never be surpassed. Unsurprisingly, there are big questions about how something like this could work so far from the scale we’re used to.
It is known that black holes have such strong gravitational fields that we cannot see them. However, their accretion disks, where materials such as disassembled stars are rotated before consumption, can be very bright. Indeed, accretion disks of supermassive black holes in the centers of galaxies make quasars the brightest objects in the Universe. The only reason why they don’t dominate our sky is because they’re not nearby-the nearest quasar is 600 million years old.
How bright quasars can be remains an open question, which has been expanded by the discovery of J0529-4351 by Siding Spring Observatory and confirmed by observations with the Very Large Telescope of the European Southern Observatory. The brightness of J0529-4351 is similar to two other powerful quasars, J0100+2802 and J2157-3602, and is located at a similar distance of about 12 billion light-years. However, there is one big difference.
J0100+2802 and J2157-3602 have gravitational lenses; in each case, the closer galaxy focuses its light so that it appears much brighter in our location than usual. If we take this lensing into account, these two quasars, although very bright, will be part of the main group of bright quasars that we find in the discovery process.
The scientists who discovered J0529-4351 were unable to detect any serious lensing. Unless there’s something they’ve missed, that makes it at least an order of magnitude brighter than its apparently similar counterparts, putting it far ahead of any other quasars, let alone other objects we know of.
“It is also the brightest known object in the universe. It’s 200 trillion times brighter than our sun,” Dr. Christian Wolfe of the Australian National University said in a statement, adding that he doubted the record would ever be broken. An alternative estimate puts the figure at 500 trillion, but what does 300 trillion of the Sun’s brightness mean between friends.
The relationship between a quasar’s brightness and the rate at which it accretes mass is not perfect. Factors such as the angle at which we see it and the speed of rotation of the hole also play a role. Nevertheless, the discoverers believe that they have enough information to calculate the rate at which this monster feeds.
Some bright quasars are powered by a star with the mass of the Sun, which is drawn into their accretion disk and eventually destroyed every year. J0529-4351 probably does the same thing every day.
J0529-4351 is not the most massive black hole ever found, but at 17 billion solar masses, it is definitely there. The apparent contradiction between its exceptional brightness and its more ordinary mass is explained by its age, as we see it earlier after the birth of the Universe than some comparable objects.
On the one hand, this means that at the time we see it, there was no time to grow to record sizes. On the other hand, feeding rates could also be higher. “In the teenage Universe, matter moved chaotically and fed hungry black holes. Today, stars move in an orderly fashion at safe distances and only rarely plunge into black holes,” said Professor Rachel Webster of the University of Melbourne.
At such a huge distance, we can’t see J0529-4351 in any detail, but its closer analogs give us some powerful clues. “It’s like a giant magnetic storm chamber with temperatures of 10,000 degrees Celsius, lightning everywhere, and wind blowing so fast it could circle the Earth in a second,” Wolf said. “This storm chamber is seven light years in diameter, which is 50 percent greater than the distance from our solar system to the next star in the Galaxy, Alpha Centauri.”
The apparent brightness of J0529-4351 is about 16th magnitude, similar to Pluto at the farthest part of its orbit. This means that modern professional telescopes will easily spot it. The problem is to notice that it is a quasar, not a star in our galaxy. Studies conducted with the Gaia space telescope failed to notice this because their AI search programs were trained on known quasars and failed to recognize something that was so out of line with other examples. “A human astronomer looking at the Gaia spectrum recognizes a quasar and redshift at a glance,” the authors noted.
Co-author Dr. Christopher Onken said: “This is a surprise that has gone unnoticed until now, given what we know about many other, less impressive black holes. It was hiding in plain sight.
