LIGO suspected that black holes emit light


Billions of years ago two black holes much more massive than the Sun — 31 and 19 solar masses each — merged in a distant galaxy. 4 January 2017 these gravitational waves traveling across the Universe at the speed of light, finally made it to Earth, where it squeezed and stretched the planet into several atoms. This was enough for the two LIGO detector in Washington and Louisiana picked up a signal and the exactly restored, what happened. For the third time in history, we directly observed gravitational waves. Meanwhile, telescopes and observatories around the world, including those in Earth orbit, looking for a completely different tone: what kind of light or electromagnetic radiation that these merging black holes would give.

Illustration of two merging black holes of comparable mass to those seen in LIGO. It is expected that such a merger should produce very little electromagnetic signals, but the presence of highly heated substances close can change that

According to our best models of physics, black holes should emit no light. A massive singularity surrounded by an event horizon, it can emit gravitational waves due to the changing curvature of space-time because it revolve around another giant mass, and General relativity implies these. Because the gravitational energy in the form of radiation must be somewhere to take, the final black hole after the merger will be a few solar masses easier the amount of the source of its origin. This is fully consistent with two other mergers, observed by LIGO: about 5% of the initial mass was converted into pure energy in the form of gravitational radiation.

The masses of the known binary systems of black holes, including three confirmed LIGO merger and one candidate for the merger

But if there is something outside of these black holes, such as accretion disk, firewall, hard shell, diffuse cloud, or anything else, the acceleration and heating of this material can generate electromagnetic radiation propagating along with our gravitational waves. After the initial discovery of LIGO, Fermi Gamma-ray Burst Monitor stated that it had recorded a surge is a high energy, coinciding with the time signal gravitational waves. Unfortunately, the ESA satellite not only failed to confirm the results of Fermi, but scientists working there discovered a flaw in the Fermi analysis of their data, completely discredited their results.

The merger of two black holes eyes of the artist, with disk accretion. The density and energy of the matter here should be enough to create gamma rays or x-ray bursts, but who knows what mother nature

The second merger has not demonstrated such allusions to electromagnetic signals, but it is not surprising that black holes had a much smaller mass, so any signal that they would be issued would be correspondingly lower in magnitude. But the third fusion was also a greater mass, more comparable with the first than with the second. Although the “Fermi” said nothing, and the ESA Integral satellite also silent were the two hint that electromagnetic radiation could take place. The AGILE satellite of the Italian space Agency revealed a weak, short-lived living outbreak that occurred half a second before the mergers on LIGO, and x-ray, radio and optical observations in the amount of identified strange.

If any of this could be linked with the merger of black holes, it would be absolutely incredible. We know so little about black holes in General, what can we say about merging these. We’ve never seen them with my own eyes, although Event Horizon Telescope like will make the end of this year. We just this year found out that black holes do not have solid shells surrounding the event horizon, but this fact was statistical. So when it comes to the possibility that black holes can have electromagnetic leakage, is to keep an open mind.

The distant massive quasars show supermassive black holes in their cores, their electromagnetic leakage is easy to detect. But we have not yet seen the merging black holes (especially with low mass, less than 100 suns) emit anything that can be detected

Unfortunately, none of these observations provides the necessary data to bring us to the fact that we conclude that black holes merging can emit anything in the electromagnetic spectrum. In General, it is difficult to obtain conclusive evidence, since even a twin-detectors LIGO, working with incredible accuracy, can not accurately determine the location of the signal of gravitational waves with greater accuracy than the constellation, or three. Since gravitational waves and electromagnetic waves move at the speed of light, it is extremely unlikely that there will be nearly 24-hour delay between these two signals. In addition, a transient event occurs at a distance which does not allow to associate it with the gravitational wave.

The observation region of the Observatory AGILE at the time of the observations LIGO, with possible location of the source of gravitational waves, shown in Magenta contours

AGILE observations can potentially hint that there is something interesting. At the time when the recorded event gravitational waves, AGILE were directed to the region of space that contains 36% of the study area LIGO. According to the researchers, “excess detected x-ray photons” appeared somewhere above the normal average background. But looking at the data, the scientists first wonder how they are convincing?

In just a few seconds before the merger of LIGO they pulled an interesting event, designated as E2 in the three diagrams above. After a complete analysis, in which they correlated that and see what kind of random fluctuations can occur naturally, they concluded that with a probability of 99.9% was something interesting. In other words, they saw real signal and not a random fluctuation. In the Universe of many objects, which emit gamma – rays and x-rays that make up the background. But is it possible to associate the incident with gravity merger of two black holes?

Computer simulation of two merging black holes with the production of gravitational waves. The question is accompanied by this signal some kind of electromagnetic spike?

If Yes, then why do others not see this? At the moment we can conclude that if black holes had an electromagnetic part, it:

  • extremely weak
  • is born only at low energies
  • has no bright optical, radio or gamma-ray component
  • does not take place simultaneously with the emission of gravitational waves.

Binary black holes with a mass of 30 solar, first recorded by LIGO, it is difficult to establish without direct collapse. Now, when they were observed twice, it became clear that such a pair of black holes are fairly common. If they have electromagnetic radiation?

In addition, all that we see is combined with the fact that merging black holes do not have magnetic parts. But could it be because we have not enough data? If we build more detectors of gravitational waves, we will see more mergers of black holes of high mass, better define their location, see more transitional events — we can know the answer to this question. If the mission and the Observatory, which should collect such data, will be constructed, commissioned and put into orbit, if needed, in 15 years we get scientific confirmation.

LIGO suspected that black holes emit light
Ilya Hel