Scientific breakthrough: a combination of gravitational and electromagnetic waves

Gravitational waves have become the most important tool available to astronomers. They are already being used to
ensure that large black holes (BH) with masses ten or more times than the Sun – and the merger of these large black hole, forming an even larger black hole, it is not uncommon to happen in the Universe. In October 2017, this tool has made a leap forward.

It has long been known that neutron stars (NWS), the collapsing remains of stars that exploded and became supernovae, are common in the Universe. And almost as many know that the NT sometimes go in pairs. (This was indirectly opened for the first time gravitational waves in the 1970s). Stars often form pairs, and sometimes both stars explode and become supernova, and their remnants in the form of n3s revolve around each other. According to Einstein's theory of relativity, a pair of stars should gradually lose energy by emitting gravitational waves into space, and slowly but surely these two objects should spiral down on each other. As a result, after millions or even billions of years, they collide and merge into larger NZ or BH. As a result of this collision, there are two events.

There is a very bright flash of light – electromagnetic waves-the details of which we can only guess. Some of these waves will be visible light, and most of them will be invisible, such as gamma radiation.
Gravitational waves arise, the details of which are easier to calculate, making them discernible, but could not be detected until LIGO and VIRGO started collecting data: LIGO over the past few years, and VIRGO over the past few months.

It is possible that we have seen the light of the merger of the two NZ before, but no one can be sure. Wouldn't it be great if we could see gravitational waves and electromagnetic waves coming from the fusion of NZ? It will be like if you see fireworks and hear an explosion – seeing and hearing at the same time better than individually, each of the signals clarifies the other. (Warning: scientists often say that detection of gravitational waves is similar to hearing. This is only an analogy, and very distant. They do not look like the acoustic waves that we hear with our ears, for many reasons – so you do not need to take the analogy literally). If we can do this and that, we will be able to obtain new knowledge about NZ and their properties in a whole new way.

And we finally found out it happened. LIGO, with its first two gravity observatories, discovered waves from two merging NPPs, located 130 million light-years from Earth, on August 17, 2017. (The fusion of NPS takes much longer than the fusion of BPS, so it's easy to distinguish them; specifically, this fusion happened so (relatively) close that it could be observed long enough.) VIRGO, with the third detector, allowed scientists to triangulate and roughly determine the location of the fusion. They received a very weak signal, but it turned out to be extremely important, as he told scientists that the merger occurred in a small region of the sky, in which VIRGO has a blind spot. And that gave scientists to understand where you should look.

Merge watched more than a minute – it is possible to compare with BH, the fusion of which occurs in less than a second. But it is still not clear what happened at the end! Formed whether the merged NZ other NZ or the black hole? It is not yet clear.

Almost exactly at the moment when the gravitational waves reached their maximum, another team of scientists, from the FERMI project, recorded an outbreak of gamma rays-electromagnetic waves of high frequency. FERMI is observing gamma rays coming from distant parts of the Universe, every day, and two-second gamma-ray burst was not unusual. It was discovered by another experiment with gamma rays, INTEGRAL. The teams exchanged information in a few minutes. Detectors of gamma-rays FERMI INTEGRAL and can be quite roughly determine the area of sky from which come these gamma rays, and LIGO/VIRGO together give only an approximate area. But the scientists saw the overlap of these sites, and the evidence was irrefutable. That's how astronomy entered a new, long-awaited phase.

Only this in itself has already been quite a major discovery. A brief flash of gamma-rays for years was occupied by scientists. One of the best guesses about their origin was the assumption of the merger of NZ. Now the riddle revealed - this assumption is obviously justified. (Or maybe not? Detected gamma rays were unexpectedly weak, so the questions still remain).

Also, the fact that these signals came with a rupture of a couple of seconds apart, after they came out of the same source, traveled a path that took them more than 100 million years, confirms that the speed of light and the speed of gravitational waves is the same – and they are both equal to the cosmic speed limit, in exact accordance with the predictions of the theory of gravity of Einstein.

Then the team quickly announced to his fellow astronomers about the need to direct their telescopes to the region, which should be the source. Dozens of telescopes, from all continents and from outer space, searched for electromagnetic waves with a large spread of frequencies, being directed in about the right direction, and scanned the sky in search of something unusual. (One of the problems was that the desired object was in the sky close to the Sun, so it could only be seen in the dark and only an hour every night). And was discovered the light! At all frequencies! The object turned out to be very bright, so it was very easy to find the galaxy in which the merger took place. Bright light was visible in gamma rays, ultraviolet, infrared light, x-ray and radio band. (This time neutrinos, particles that can be used as another way to observe remote explosions were not detected).

And with so much information you can learn so much!

The most important, perhaps, is that: from the laws present in the spectrum of light, it follows a confirmation of the hypothesis that the fusion of neutron stars are important, perhaps the predominant sources of many heavy chemical elements – iodine, iridium, cesium, gold, platinum and so on – arising at high temperatures in such collisions. Most likely their source was considered to be the same supernova that formed the NC. But now, judging by around the, it turned out, that the second phase life NZ – merging, not the birth of – so same is important. This is amazing, because the fusion of NZ takes place much less frequently than supernovae explosions. In our Galaxy, the milky way supernova breaks out about once a hundred years, but between the emergence of such "kilon" in the merges of NZ, tens of thousands of years pass.

If anything in this news is disappointing, it's the following: almost everything that was observed in these experiments was predicted in advance. Sometimes it's more important and useful if your predictions don't come true at all, because then you know how much you have to learn. Obviously, our understanding of gravity, NZ, their mergences, all kinds of electromagnetic radiation sources that occur in these mergers is much better than you might think. But, fortunately, there are a few new puzzles. X-rays are late; gamma rays were weak – soon we will know more about that, because NASA has to hold a new conference.

Some of the topics of the conference:

New information about the innards of NZ is obtained, affecting what size they can be and how they merge.
The first image of the source of gravitational waves in visible light, located on the outskirts of a distant galaxy, was obtained using the Swope telescope. The center of the galaxy is a circle of light, and the arrows indicate the place of the explosion.
Theoretical calculations of the kilon explosion indicate that the fragments of the explosion should quickly block the visible light, so the explosion quickly fades in visible light-but infrared light remains much longer. Observations of telescopes in the visible and infrared ranges confirm this aspect of the theory; these proofs can be seen in the picture above, where four days later the bright spot became much dimmer and much redder.

Estimate: the total mass of gold and platinum in this explosion is much greater than the mass of the Earth.
Estimate: these neutron stars formed about 10 billion years ago. They revolved around each other most of the history of the Universe, and ended up only 130 million years ago, giving rise to a recently discovered explosion.
Big mystery: all the previous gamma-ray flashes we recorded glowed in ultraviolet light and x-ray in the same way as in the gamma range. But this time the x-rays did not appear, at least not immediately. It was a big surprise. The Chandra telescope took 9 days to detect x-rays that were too dim for any other telescope. Does this mean that the two NZS created the BH, which then created a jet (relativistic stream) of matter directed not directly at us and illuminating matter in interstellar space? This possibility was offered 20 years ago, but some evidence in its favor was obtained for the first time.

Another surprise: the discovery of radio waves took 16 days, and opened them with the help of the most powerful of the existing radio telescopes, Very Large Array. Since then, the radio emission increases the brightness! This, as in the case of x-rays, supports the idea of having a jet directed away from us.