Space radio broadcasts more and more interesting

They come suddenly, from different directions in the universe, are a cacophony of many frequencies, and cut off after just a few milliseconds. Until recently, it was believed that these signals do not repeat. However, a few years ago, one of the FRB broke this rule, and to this day it still comes from time to time. As Nature reported in January, a second such case was recently discovered.

Previous repeating fast radio flash (FRB – ) comes from a small dwarf galaxy in the constellation Chariot, about 3 billion light-years away. At least we think so, because only the direction is given. Perhaps it is sent by another object that we do not see.

In an article published in Nature, scientists report that the Canadian radio telescope CHIME (Canadian Hydrogen Intensity Mapping Experiment) thirteen new radio flares were registered, including six from one point in the sky. Their source is estimated to be 1,5 billion light-years away, twice as close to where the first repeating signal was emitted.

New tool - new discoveries

The first FRB was discovered in 2007, and since then we have confirmed the presence of more than fifty sources of such impulses. They last milliseconds, but their energy is comparable to that produced by the Sun in a month. It is estimated that up to five thousand such outbreaks reach the Earth every day, but we are not able to register them all, because it is not known when and where they will occur.

The CHIME radio telescope was designed specifically to detect this kind of phenomena. Located in the Okanagan Valley in British Columbia, it consists of four large semi-cylindrical antennas that scan the entire northern sky every day. Of the thirteen signals recorded from July to October 2018, one coming from the same place was repeated six times. Scientists have called this event FRB 180814.J0422 + 73. Signal characteristics were similar FRB121102which was the first known to us to repeat itself from the same place.

Interestingly, the FRB in CHIME was first recorded at frequencies on the order of only 400 MHz. Earlier discoveries of radio bursts were most often made at a fairly high, close to radio frequency. 1,4 GHz. Detections occurred at a maximum of 8 GHz, but the FRBs known to us did not appear at frequencies below 700 MHz - despite numerous attempts to detect them at this wavelength.

The detected flares differ from each other in terms of time dispersion (dispersion means that as the frequency of the received wave increases, parts of the same signal recorded at certain frequencies reach the recipient later). One of the new FRBs has a very low dispersion value, which may mean that its source is relatively close to the Earth (the signal is not very scattered, so it could have come to us at a relatively short distance). In another case, the detected FRB consists of many single successive bursts - and so far we know only a few.

Together, the properties of all the flares in the new sample seem to suggest that they originate primarily from regions that scatter radio waves more strongly than the diffuse interstellar medium present in our Milky Way. Regardless of what their source is, FRBs are generated this way. near high concentrations of a substancesuch as the centers of active galaxies or supernova remnants.

Astronomers will soon have a powerful new tool that will square mileage, i.e. a network of radio telescopes located in different parts of our planet, with a total area of ​​one square kilometer. SKA it will be fifty times more sensitive than any other known radio telescope, which will allow it to register and study precisely such fast radio bursts, and then determine the source of their radiation. The first observations using this system should take place in 2020.

Artificial intelligence has seen more

In September last year, information appeared that, thanks to the use of artificial intelligence methods, it was possible to study in more detail the radio flares sent by the mentioned object FRB 121102 and systematize knowledge about it.

It was necessary to analyze 400 terabytes of data for 2017. To listen to data from Green Bank Telescope new pulses from the mysterious source of recurrence FRB 121102 have been detected. Previously, they were bypassed by conventional methods. As the researchers note, the signals did not form a regular pattern.

As part of the program, a new study was conducted (its co-founder was Stephen Hawking), the purpose of which is to study the universe. More precisely, it was about the next steps of the subproject, defined as an attempt to find evidence of the existence of extraterrestrial intelligence. It is being implemented in conjunction with SET(), a scientific project that has been known for many years and is engaged in the search for signals from extraterrestrial civilizations.

The SETI Institute itself uses Allen Telescopic Nettrying to get data in higher frequency bands than previously used in the observations. New digital analytical equipment planned for observatories will allow both the detection and observation of frequency bursts that no other instrument can detect. Most scholars point out that in order to be able to say more about FRB, you need to many more discoveries. Not tens, but thousands.

One of the localized FRB sources

Strangers are quite unnecessary

Since the first FRBs were recorded, researchers have tried to determine their causes. Although in the fantasies of science fiction, scientists rather do not associate FRB with alien civilizations, seeing them rather as the consequences of collisions of powerful space objects, for example, black holes or objects called magnetars.

In total, about a dozen hypotheses regarding mysterious signals are already known.

One of them says they came from rapidly rotating neutron stars.

The other is that they come from cosmic cataclysms such as supernova explosions or neutron star collapse to black holes.

Another seeks an explanation in theoretical astronomical objects called flashers. A blitzar is a variant of a neutron star that has enough mass to turn into a black hole, but this is hindered by centrifugal force due to the star's high rotational speed.

The next hypothesis, although not the last in the list, suggests the existence of the so-called contact binary systemsthat is, two stars orbiting very close together.

FRB 121102 and the recently discovered signals FRB 180814.J0422+73, which were received multiple times from the same source, appear to rule out one-off cosmic events such as supernovae or neutron star collisions. On the other hand, should there be only one cause of FRB? Perhaps such signals are sent as a result of various phenomena occurring in space?

Of course, there is no shortage of opinions that the source of the signals is an advanced extraterrestrial civilization. For example, the theory has been proposed that the FRB may be leaks from transmitters planet sizepowering interstellar probes in distant galaxies. Such transmitters could be used to propel the interstellar sails of spacecraft. The power involved would be enough to send about a million tons of payload into space. Such assumptions are made, including Manasvi Lingam from Harvard University.

However, the so-called principle of Occam's razorAccording to which, when explaining various phenomena, one should try to be simple. We know well that radio emission accompanies many objects and processes in the Universe. We do not have to look for exotic explanations for FRBs, simply because we are not yet able to connect these outbreaks with phenomena that are visible to us.