The largest black hole in a known part of the universe

Human experience shows that you can not quickly come to the light. It is necessary to go through twilight on the manifesting day before noon, and the sun will flood the landscape.
- Woodrow Wilson

We know how the majority of black holes are formed in the Universe: after the death of massive stars (from 20 solar masses and more), black holes with a mass from three solar ones appear. Such stars burn fuel contained in the core faster than others - in just a few million years - and when the core can no longer burn, they collapse. And nothing inside the stars, neither atoms, nor nuclei, nor quarks with gluons, can resist the gravitational collapse, if the star had enough mass!



When a star reaches a mass of 100 solar, very strange things begin to happen in its depths. In particular, the inner core of the star is heated so much that a significant part of the photons reaches energy exceeding 511 Kev, an important energy threshold. It is large enough for two colliding photons to spontaneously generate an electron-positron pair!


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In an ordinary star, the outward pressure and the gravitational contraction inward turn out to be balanced and hold the star. But this pressure turns out to be photons moving at the speed of light, and if these photons suddenly turn into slowly moving particles of matter and antimatter, the pressure drops, and, possibly, critically.

Depending on the mass of the star, it can all experience an out-of-control fusion reaction that destroys the entire star, or, for the most massive stars, most of this mass can collapse into a black hole! This is what we expect from a large number of stars in the star cluster nearest to us: R136 in the Tarantula nebula.



The universe has been around for many years, and it had many opportunities to create big, supermassive stars that lived, died, and turned into black holes. In the center of galaxies, in particular, these black holes have the opportunity to merge and grow strongly. Over time, in most galaxies supermassive black holes appear - our galaxy containing a black hole of four million solar masses will not be an exception. It can be measured almost directly by observing the rotation of known stars around a point that does not emit light. For the existence of these orbits, a mass of 4,000,000 solar is required.



It must be remembered that in our galaxy there are from 200 to 400 billion stars, so the mass of our black hole is about 0.1% of the entire mass of the galaxy. This is a small part, but a big number. Now imagine that our galaxy is not among the large ones, and our black hole is at the end of the list of supermassive ones.

There are huge galactic monsters and the largest of those closest to us will be Messier 87, a giant galaxy in the center of the Virgo cluster.



This is the largest of the nearest galaxies, with a mass exceeding 200 times our mass. You may find the “line” that comes out of it strange. As far as we know, this is a relativistic jet of matter 5000 light years long, coming from the center of the galaxy! The only object we know that can produce such a phenomenon is a supermassive black hole, noticeably larger in size than the one in the center of our galaxy.

If we need to measure the mass of this black hole, it is better to turn to X-rays of the Chandra space telescope.



The most recent measurements show that in the galaxy there is a supermassive black hole weighing 6.6 billion solar - an amazing number, 1500 times greater than the mass of a giant in the center of our galaxy! This can be confirmed by measurements of the jet in the radio band, conducted on the VLA.



What is interesting (to me) is that the previous estimate of the mass of the central black hole came from the measurement of flares in the center of M87, which gave a mass of 6.4 billion solar. In other words, we are well versed in what is happening there!

But until you decide that Messier 87 is some kind of abnormal anomaly, let me show you most of the Virgo cluster.



In addition to M87, there are other giant elliptical galaxies at about the same distance, including M84, M49 and M60, each of which has a black hole weighing more than a million solar ones. It is believed that usually — although there are variants — elliptical and lens-shaped galaxies form through the merging of several spiral ones, their central black holes also merge, and therefore about 0.1% of the entire mass of the galaxy is contained in the central black hole.

Therefore, we can assume that in search of the largest black hole you need to study the largest galaxies. Let's try!



This cluster of Abell 2029, located at a distance of 1.07 billion light years, or 20 times farther than the cluster of Virgo. At its center is the largest of all known galaxies of the Universe: IC 1101. The galaxy extends over two million light-years in the most elongated direction, many times larger than Messier 87, and has the largest galaxy mass known in the Universe. It extends over a distance twice the distance from the Milky Way to Andromeda! Including dark matter, its mass is equal to 100 trillion solar, or approximately the entire total mass of the Virgo cluster. (If you google images of this galaxy, you can stumble upon too exaggerated pictures. Be careful).

And what about her black hole?



If we knew ... It is too far away from us, not active enough, and our current space instruments do not have sufficient accuracy to measure its parameters. Maybe one day! And if I made a bet, then I would be ready to bet that there really is the largest black hole in the known Universe.

It would be a smart bet, but I would not be surprised if I made a mistake, and the reason for a possible mistake will surprise you!



This Perseus Cluster, a less impressive cluster than Abell 2029. The large active galaxy at its center is stunning, and the selected galaxy is completely unprepossessing: NGC 1277. This cluster is relatively close to us, just over 200 million light years away - and the distance to NGC 1277 is very typical, about 220 million light years. This is not the largest galaxy, not the most elliptical, not the most massive, not the brightest. In general, judging by its stars and the total mass of 120 billion solar, it is even less massive than the Milky Way!

But if you watch the gas in its center (and it is located close enough to us to detect it), you can see how it moves and measure its kinematics. The faster the speed increases as you approach the center, the better you can estimate the central mass of the galaxy.



In this galaxy there should be a central black hole with a tremendous mass of 17 billion solar, making up an amazing 14% of the total mass of the galaxy! This is an unprecedented number, and it is not only the most massive of all the black holes we have found, but also the largest percentage of the ratio of the mass of a black hole to the galaxy. There are other cases with quite large percentages - NGC 4486B and Henize 2-10 - but these galaxies are smaller.

Therefore, of course, it is possible that the largest galaxy in the Universe contains the largest black hole, but it is also possible that the owner of the record will be an unremarkable lenticular galaxy, just for reasons we don’t yet understand, containing a huge black hole!

On the other hand, within the limits of the error of our measurements, there is another candidate for the largest black hole in the known Universe, which is very different from the NGC 1277 considered by us.



See the point indicated in the figure? This is the galaxy OJ 287, belonging to a special class of objects called blazars. These are compact extragalactic sources of radio waves, and one of the most energetically powerful objects of the Universe. This is a special type of quasar - an active galaxy - in which one of the most powerful relativistic jets is directed in our direction!

Recall how objects like these active galaxies work: their supermassive black holes feed on stars, gas, and other space objects. Since they tear apart structures with the help of gravity and accelerate them greatly, feeder ones make them sloppy. And although this is one of the main ways of growing black holes, this is also one of the ways the Universe tells us about their presence!



The brightness of this source changes periodically — with a period of 11–12 years — and it emits flashes in a narrow double burst associated with maximum brightness. It looks beautiful in radio waves and X-rays, and the observations coincide not only with the fact that there is a supermassive black hole of enormous dimensions, but also with the fact that supermassive smaller black holes move around it in orbits.



This galaxy is about 3.5 billion light-years distant from us, and contains perhaps the largest known black hole of 18 billion solar masses. (But due to measurement uncertainties, the results strongly overlap with NGC 1277). The most amazing sight of this galaxy - and the reason that we can explore its central region - is the black hole of 100 million solar masses (25 times more massive than the black hole in the center of the Milky Way), revolving around an even bigger black hole!



A system with an orbit 300 times larger than Pluto’s orbit around the Sun, making a revolution in just 12 years, will allow us — if we calculate everything correctly — to carry out the greatest test of the general theory of relativity. While the precession of the elliptical orbit of Mercury around the Sun is 43 "over a hundred years due to relativistic effects (1 ° is 3600"), this smaller black hole should have a precession of 39 ° per revolution, and should spiral down into big black hole in just a few thousand years!

And these two galaxies, the nearest and the smallest NGC 1277 and the very distant OJ 287, contain the largest black holes known to us in the Universe. Of course, there are black holes and bigger ones, but to find them, we need more luck, time and better radio telescopes and X-ray equipment.