This Massive Black Hole Is Mysteriously Quiet, And Astronomers Don’t Know Why
“Messier 51, the Whirlpool Galaxy, is one of astronomy’s most spectacular objects. This enormous, face-on galaxy was the first one ever to reveal its spiral structure. The small object alongside it, the galaxy NGC 5195, is interacting and merging with the Whirlpool galaxy. Such mergers trigger new waves of star formation, create grand spiral arms, and activate supermassive black holes.”
That’s the theory, at any rate. Yet when we look at Messier 51, located just outside of the Big Dipper in the night sky, we find that the X-rays being emitted from it are spectacularly minimal. After the Chandra X-ray telescope made its observations, we simply assumed the higher-energy X-rays would make up for the missing radiation, but they show an extreme shortage as well, with neutron stars on the outskirts outshining them.
Perhaps something new is at play. Perhaps active black holes flicker on-and-off faster than we previously thought. There’s a new puzzle, and that means there’s more to learn.
Meet The Universe’s First-Ever Supermassive Binary Black Holes
“In 1891, the object OJ 287, 3.5 billion light years distant and a blazar itself, optically bursted. Every 11-12 years since, it’s produced another burst, recently discovered to have two, narrowly-separated peaks. Its central, supermassive black hole is 18 billion solar masses, one of the largest known in the Universe. This periodic double-burst arises from a 100-150 million solar mass black hole punching through the primary’s accretion disk.”
The big problem with black holes is that, well, they’re so dark. They don’t emit any detectable light of their own, so we have to rely on indirect, secondary signals to infer their existence. That usually arises in the form of radio and X-ray radiation from matter that gets accelerated by the black hole’s extreme gravity, as well as from the magnetic fields that an accretion disk around the black hole can create. The radiation can form jets, and when a jet points at our eyes, we see a blazar. Well, the system OJ 287 has a periodic blazar that flares in a double-burst every 11-12 years, indicative of a large, supermassive black hole orbiting an even more massive behemoth, punching through the accretion disk twice with every orbit.
Come meet OJ 287, first found to burst way back in 1891, and still one of only two supermassive black hole binaries known in the Universe!
The Youngest, Most Massive Black Hole Is A Puzzle For Astronomy
“Recently, a new black hole, J1342+0928, was discovered to originate from 13.1 billion years ago: when the Universe was 690 million years old, just 5% of its current age.
It has a mass of 800 million Suns, an exceedingly high figure for such early times.
Even if this black hole formed from the very first stars, it would have to accrete matter and grow at the maximum rate possible — the Eddington limit — to reach this size so rapidly.
Fortunately, there are other ways to grow a supermassive black hole.”
We did it! We found our most massive, most distant quasar of all-time, telling us we’ve got a supermassive black hole that’s 800 million times as massive as our Sun when the Universe was just 5% of its current age. Even factoring in all we know about the formation and growth of black holes, from the early Universe and throughout all of time, we expect that there will only be around 20 black holes this large existing this early. Are there going to be more? Will we have to revise our current theories of cosmology and structure formation? Or is this simply an indication that we’re beginning to discover the brightest, most massive objects that are out there at any distance at all? As always, more and better data will decide, but here’s what we know so far.
Come get the full story, and some spectacular visuals (and video!) on today’s Mostly Mute Monday.