J2157 *, an ultra-massive black hole holding many records, has a giant appetite. This ancient monster would devour almost a solar mass per day, for a total mass of 34 billion Suns.
If J2157 * were to be a boxing champion, he would definitely enter the heavyweight category. With a mass equivalent to 34 billion Suns it is one of the most massive black holes discovered to date in the Universe. Recent analyzes reveal that it would be endowed with a hunger on the scale of its proportions: like a cosmic Cronos, it would engulf nearly a solar mass per day. This ogre appetite makes it the fastest growing black hole ever measured.
“The mass of the black hole is also 8,000 times that of the one in the center of the Milky Way,” comments astronomer Christopher Onken. “If the black hole of the Milky Way wanted to be overweight, it would have to swallow two thirds of all the stars in our Galaxy. This analogy gives a clear overview of the dimensions of the monster we are dealing with. Its gigantism also tipped it into the category of ultramassive black holes, even more imposing than the supermassive black holes which inspired the Muse group.
The discovery of J2157 *, located several billion light years from our Solar System, was announced in 2018 by the research team of the Australian National University (ANU). Like most of its ultra-massive peers, it houses a hyper-energetic quasar: the brightest ever observed to date. At the time of its discovery, scientists were still far from suspecting the size of the creature they were facing, estimating its mass at 20 billion Suns, and its meals at half a solar mass per day.
Since then, a new study published in the journal Monthly Notices of the Royal Astronomical Society has come to contradict these figures and proposes the new values previously mentioned. With such a mass, its Schwarzschild radius would be equivalent to 670 astronomical units, or nearly 6 times the diameter of our Solar System (measured not at the level of Pluto’s orbit, but at the limits of the heliopause). At a distance of about 12.5 billion light years, J2157 * tells us about the adolescence of our Universe and its ability to produce such voracious monsters at such a young age (it is estimated that the first black holes would be appeared at the same time as galaxies and stars, 400 million years ago after the Big Bang).
“It is the largest black hole ever observed so early in the history of the Universe,” said Onken. Even more surprising: quasars harboring supermassive black holes were not uncommon in the times following the Big Bang, as several studies have recently revealed. This discovery forces us to revise our current cosmological models. By studying the black hole and its galaxy, the researchers hope to understand a little better how such structures can form in such a short time. “Is this galaxy one of the titans of the young Universe, or has the black hole only devoured an extraordinary part of its environment?” We will have to keep digging to find an answer. “