Supermassive black hole, the theory that it is expanding with the universe. What do you mean?

What exactly is the universe? A ridiculously large-scale story.

It was in 2015 that humankind first observed gravitational waves that were considered undetectable. The impact of two supermassive black holes colliding violently became ripples in space-time, and the gravitational wave detector LIGO captured the place where it reached the earth over 1.3 billion years. Many similar gravitational waves have been detected since this historic observation, which has helped to deepen our knowledge of collisions between black holes.

But that's not all. At this point, a research team who was studying the gravitational wave data has come up with an insanely novel hypothesis. By reading the gravitational wave data, it seems that the supermassive black hole is expanding in conjunction with the universe.

Inflating universe

The universe is expanding. And its expansion continues to accelerate. The currently known laws of physics have not yet explained why they are accelerating, and so far it is said that the mysterious "dark energy" is accelerating the expansion.

And it is said that just because the universe is expanding does not mean that the things that exist in the universe are expanding together with the universe.

An easy-to-understand analogy is a balloon. If you inflate a balloon with two dots drawn in advance, the distance between the dots will increase as the balloon grows, and it will appear that the dots move away from each other.

In this way, when observing galaxies far away from the earth, we can see that redshift (a phenomenon in which the wavelength of light emitted by celestial bodies is extended and observed) occurs. This means that the galaxies are accelerating and moving away from each other, but it is thought that it is not because the galaxies themselves are expanding, but because the space-time that separates them is expanding. rice field.

A black hole that swells with the swelling universe

However, it is. A new hypothesis has been proposed that overturns this conventional way of thinking. It is said that the universe is expanding together with the celestial bodies that exist in the universe. In other words, when the balloon called the universe is inflated, the dots themselves may become larger. That's right.

The Earth and the solar system to which it belongs are bound by gravity, so we do not directly experience the expansion of the universe. But what about supermassive black holes?

The mass of a supermassive black hole is remarkably large, and its life as a celestial body is remarkably long, so it seems that it expands together as the universe expands. A team of researchers, including Professor Kevin Croker, a space physicist at the University of Hawaii at Manoa, tried to theoretically elucidate the expansion.

Inflating black holes collide with each other

The research team investigated in detail the gravitational waves observed by the gravitational wave detector LIGO in 2015, and the two supermassive black holes that were the source of the gravitational waves.

Said Professor Croker in an email.

The team modeled the size of two supermassive black holes in proportion to the expansion of the universe. Then, it seems that the black holes became larger as they approached each other.

From this result, it seems that all supermassive black holes are expanding in the same way, but unless gravitational waves can be observed, it is difficult to detect the black hole itself, so it is difficult to verify. .. But if this hypothesis is correct, even the supermassive black hole located in the center of our galaxy will grow with the expansion of the universe.

According to Professor Croker

No, amateurs don't really understand ...

Interlocking with the universe

When calculating the mass of a black hole, the universe is usually considered to be unexpanded. In short, since the expansion of the universe is stopped once and the mass of the black hole is calculated in a certain moment, what kind of change the subsequent expansion of the universe will bring to the mass of the black hole is taken into consideration. I haven't.

A black hole is a celestial body with the highest density in the universe, and is a remnant of a heavy star that could not bear its own weight and collapsed. Black holes may collide with each other and swallow each other because the tremendous gravity attracts surrounding objects. Such fusions can take a very long time, sometimes billions of years.

Researchers think that the size of the universe should have changed considerably between the time when each black hole was born and the time when the black holes collided with each other because it takes such a long time. is. According to postdoctoral fellow Michael Zevin, a professor of astrophysics at the University of Chicago and a NASA Hubble Fellow.

And that. Does that mean that the size of the universe itself is also involved?

This "cosmological coupling", that is, the phenomenon that the properties of celestial bodies and particles are linked to the properties of the universe, is only a hypothesis, but it seems that photons are examples other than black holes. .. However, in the case of photons and the universe, there is a contradictory relationship, and it seems that the energy of photons decreases with the expansion of the universe, as opposed to the increase of the energy of the black hole with the expansion of the universe. Because it will be stretched).

Are all matter linked to the universe?

moreover. What if this "space coupling" phenomenon is not limited to black holes and photons?

Professor Gregory Tarlé, a space physicist at the University of Michigan, explains in an email:

Hmmm, don't blame the universe for weight gain.

Of course, this is just a hypothesis. But with the availability of new, more powerful gravity detectors currently under construction, more detailed data should be available in gravity wave research. Furthermore, if the accuracy of the telescope is further refined in the future, it will be possible to focus on and shoot celestial bodies that exist in the universe as far as the eye can see.

As the data collected about the universe in the future becomes more detailed and clearer, it may be possible to get a hint as to whether this universe is a balloon.

Reference: Astrophysical Journal Letters