The riddle of the mysterious radio pulses from deep space


Since 2007, astronomers have recorded about 20 of mysterious radio pulses, which were far beyond our Galaxy.

In the Universe there is no shortage of strange and not witnesses of the phenomena — from black holes to strange planets. Scientists have something to smash his head.

But one mystery in recent times is especially astronomers — mysterious bursts of radio emission in space, known as fast radio pulses.

They last only a few milliseconds, but it stands out about a million times more energy than is produced during the same period of time in the Sun.

Since the discovery of the first such pulse in 2007, astronomers were able to register at least 20 such cases, all sources were outside our Galaxy and were evenly distributed across the sky.

However, the telescopes, as a rule, at any given point in time, watching small areas of the sky.

If we extrapolate the findings to the entire sky, as astronomers suppose, the number of such pulses can reach 10 thousand a day.

And nobody knows the cause of this phenomenon.

Astronomers, of course, plenty of possible explanations, some of which sound very exotic: the collision of neutron stars, exploding black holes, breakages cosmic strings and even the results of the activities of extraterrestrial intelligence.

“There are theories that attempt to explain the nature of fast radio pulses, there is more than was actually pulses,” says Duncan Lorimer, an employee of American West Virginia University and head of the research group that discovered the first fast pulse (also called pulse Lorimer). — Is fertile ground for theorists.”

But even if the explanation of the nature of fast radio pulses will be much more commonplace, they still can bring the science of great benefit.

These signals are similar to the laser beam linking the Universe and greeters on your way in the magnetic field, plasma and other cosmic phenomena.

In other words, they capture the road information about the intergalactic space, and could represent a unique tool to study the Universe.

“They are, without a doubt, revolutionizing our understanding of the Universe, since they can produce very accurate measurements,” says pang UE-Li, an astrophysicist at the University of Toronto.

But before that happens, scientists need to gain a better understanding of the nature of fast radio pulses.

Over the past few months, astronomers were able to achieve in this area of promising progress.

The first thing that struck Lorimer discovered in them the impulse was his intensity.

Lorimer and his colleagues looked at archival data sets collected using the Parkes radio telescope in Australia. They were looking for a radio — for example, those that emit a rapidly spinning neutron star called a pulsar.

These stars, each with the diameter of a major city, have the density of an atomic nucleus and can spin at over 1,000 revolutions per second.

They emit narrow streams of radio emission, therefore they are called cosmic lighthouses.

Radio signals emitted by pulsars to the observer from Earth looks like a ripple.

But the signal, discovered by a team of Lorimer, was very strange.

“His intensity was so great that suppressed the operation of the electronic components of the telescope, — says Lorrimer. — For the source of radio emission is extremely unusual.”

The pulse lasted about 5 milliseconds, after which its intensity fell.

“I remember the first time I saw the chart momentum,” says team member Lorimer Matthew Bales, an astronomer at the Australian Swinburne University of Technology. — I was so excited that night that I couldn’t sleep”.

For about five years after the discovery of the Lorimer pulse, he remained an unexplained anomaly.

Some scientists believed that this is just the instrumental noise. And in a study published in 2015, said that similar to the parameters of the pulses are recorded during operation of the microwave, installed in the utility section of the Observatory parks.

However, starting in 2012, astronomers working at other telescopes, have spotted a few of these radio pulses, thus confirming that the signals actually come from space.

And not just from space — their sources are outside our Galaxy, probably billions of light years from Earth. This assumption was made on the basis of measurements of the phenomenon, known as dispersion effect.

During its journey through the Universe radio waves interact with the plasma electrons, found their way. This interaction causes a reduction in the wave propagation, frequency-dependent signal.

Radio waves of higher frequencies arrive to an observer a little faster than radio waves of low frequency.

By measuring the difference in these values astronomers can calculate after how much plasma had to pass the signal towards the observer, giving them an approximate idea of the distance of the source pulse.

Radio waves coming to us from other galaxies. Just before the opening of fast radio pulses, scientists did not observe signals of such high intensity.

So, quasars are the active nuclei of galaxies, in which, as scientists believe, are the massive black star — emit huge amounts of energy, including radio frequency energy.

But the quasars in other galaxies are so far away from us that we accept from them the radio signals extremely weak.

They could even drown out the radio signal from the mobile phone placed on the moon, says Bales.

Another thing fast radio pulses. “The existence of a signal, whose intensity is a million times greater than anything previously discovered, excites the imagination,” says Bales.

Especially given the fact that the rapid pulses can indicate a new, unexplored physical phenomena.

One of the most controversial explanation for their origin is related to the so-called cosmic strings — hypothetical one-dimensional folds of space-time which can reach at least tens of parsecs.

Some of these strings may have superconducting properties, and it can flow an electric current.

The hypothesis proposed in 2014, cosmic strings sometimes break, leading to the emission of electromagnetic radiation.

Or, says pane, explanation of these outbreaks can be explosions of black holes.

The gravitational field of a black hole is so massive that even light hitting it, not able to move back.

However, in the 1970s, the famous British theoretical physicist Stephen Hawking suggested that energy could evaporate from the surface of the aging of black holes.

If we assume that at an early stage of development of the Universe it was formed black holes small sizes, but now they might just evaporate and eventually explode, resulting in the immediate emission of radiation.

In February 2016, astronomers announced that they may have managed to make a breakthrough in research.

A team of scientists under the leadership of Evan Kiana working in the headquarters of radio interferometer “Square kilometer grid” (Square Kilometre Array) is a British Astrophysics the Jodrell Bank centre, analyzed the parameters of one fast pulse, was in April 2015.

According to the findings of astronomers, the source pulse was in the galaxy located 6 billion light years away and composed of old stars.

For the first time, researchers were able to determine the location of the radio source with an accuracy to the galaxy, that was accepted in the scientific community as an extremely important discovery.

“The establishment of the galaxy, which is the source of a rapid pulse, is a crucial piece of the puzzle,” says Bales, who worked in the team of Kiana. — If you are able to determine the galaxy, we are able to know how far away the source is located”.

You can then accurately measure the volume of the pulse energy and begin to discard the most implausible theories about its origin.

In this case, the parameters of the observed pulse testified to the probability of at least one scenario: the collision of pairs of neutron stars rotating around each other.

It seemed that the mystery of the nature of fast radio pulses nearly revealed. “I am very excited about the results of this study,” says Lorrimer.

But just a few weeks scientists Edo Berger and Peter Williams of Harvard University put this theory into question.

Insights team Kiana was based on the observation of the phenomenon, which scientists have interpreted as the attenuation of the radio signal at the end of the fast pulse.

The fading of the source signal reliably was in the galaxy located 6 billion light years from Earth, and researchers believed that the rapid pulse came from the same place.

However, according to Berger and Williams, the fact that Kian took over the residual — fading — signal, rapid pulse nothing had.

They have carefully analyzed the characteristics of the residual signal, sending to a remote galaxy is an American radio telescope “Corbella antenna array” (Very Large Array).

It was found that it is a separate phenomenon caused by fluctuations in the brightness of the galaxy due to the fact that at its center is a supermassive black hole swallowing cosmic gas and dust.

In other words, a shimmering galaxy was not a place from which he was released a quick pulse. Just in the field of view of the telescope it was accidentally — or the true source, or in front of him.

And if the radar pulse was sent from this galaxy, perhaps, and the reason it was not the collision of two neutron stars.

Neutron scenario there is still one weak spot. “The radiation frequency fast radio pulses is much higher than the frequency of the radiation expected in the collision of neutron stars,” says the American Maxim Lyutikov of Purdue University.

In addition, collisions of neutron stars occur several orders of magnitude less likely frequency of fast radio pulses, so that all cases only be explained by this phenomenon is impossible.

And soon new scientific data reduced even more the likelihood of this explanation.

In March 2016, a team of astronomers announced a stunning discovery. They studied the microburst, was in 2014 the Arecibo Observatory in Puerto Rico. It turned out that we are not talking about a single phenomenon — the pulse was repeated 11 times for 16 days.

“It was the biggest opening since the first fast pulse, — says pang. It puts an end to the huge number of proposed hypotheses.”

All registered first fast radio pulses were single — repeat signals from the same sector of the sky was not recorded.

So scientists assumed that they could result from cosmic cataclysms, in each case occurring only once — for example, explosions of black holes or the collisions of neutron stars.

But this theory does not explain the possibility (in some cases) repetition of the radio pulses in quick succession. Whatever the cause of such series of pulses, the conditions for their occurrence should be kept for a certain time.

This significantly narrows the list of possible hypotheses.

One of them, a study which deals with buttercups, States that sources of fast radio pulses can be young pulsars, neutron stars, rotating at a speed of one revolution per millisecond.

Over time, the rotation of the pulsar slows down, and the part of the rotational energy could be emitted into space in the form of radiation.

It is not clear exactly how pulsars can emit rapid pulses, but we know that they are able to radiate short pulses of radio waves.

So, a pulsar located in the crab nebula, presumably about 1000 years. He is relatively young and is one of the most powerful known pulsars.

The younger the pulsar, the faster it spins and the more energy it has. <url> calls these objects “pulsars on steroids”.

And although the pulsar in the crab nebula currently does not have sufficient energy to emit quick pulses, it is possible that immediately after the occurrence he could do it.

Another hypothesis States that the source of energy for fast pulses — not the rotation of the neutron star and its magnetic field, which can be a thousand trillion times stronger than earth’s.

Neutron stars with exceptionally strong magnetic field, the so-called Magnetar, can emit rapid pulses through a process similar to those in which there are solar flares.

Rotation of the Magnetar magnetic field in the corona — thin outer layer of the atmosphere — change the configuration and lose stability.

At some point, these fields behave as if the snap of the whip. Frees the flow of energy that accelerates charged particles, which emit radio pulses.

“Magnetars in the Universe quite a lot,” says Bales. — They are unstable, which may explain the origin of fast radio pulses”.

Hypothesis associated with neutron stars, a more conservative and based on relatively well understood phenomena, therefore, are more likely to occur.

“One hypothesis is the occurrence of rapid pulses that I believe any serious and who seriously discuss with colleagues relevant to neutron stars,” says Bales.

He admits, however, that this approach may be somewhat one-sided. Many astronomers, the study of fast radio pulses, and also study neutron stars, so that their tendency to consider the first through the second prism clear.

There are also more unconventional explanations. For example, several researchers suggested that the rapid radio pulses arise as a result of collisions of the pulsar with asteroids.

It is not excluded that the faithful are multiple hypotheses, each of which explains a specific case of fast radio pulses.

Perhaps, some impulses are repeated and others are not, that is not fully exclude the hypothesis of collisions of neutron stars and other disasters on a cosmic scale.

“It may be that the answer is very simple, says <url>. — But it may happen so, that we are dealing with unexplored aspects of physics, with new astrophysical phenomena.”

Regardless of what actually will be the rapid radio pulses, they can benefit space science.

For example, they could be used to measure the volume of matter in the Universe.

As already mentioned, the radio waves meet on their way intergalactic plasma, which slows their speed depending on the wave frequency.

Besides being able to measure the distance to the signal source, the difference in velocity of the waves also gives an idea of how many electrons are located between our galaxy and the radiation source.

“Radio waves encoded information about the electrons that make up the universe,” says Bales.

This gives scientists a rough estimate of the quantity of matter in space that will further help them in calculating the models of the Universe.

The uniqueness of fast pulses is that they are sort of space laser beams, said pang.

They stitch the space in a certain direction and have a high enough intensity to provide excellent measurement accuracy.

“This is the most accurate of measuring tools in the study of distant objects in the line of sight,” he explains.

So, in his words, the radio can tell you about the structure of plasma and magnetic fields near the source.

With the passage of the radio plasma can flicker — just as the stars twinkle, if you watch them through the earth’s atmosphere.

Measurement of the characteristics of this flicker will allow astronomers to measure the sizes of areas of plasma with a precision of several hundred kilometers. Due to high scientific potential, and not least because of the unexplainable phenomena in the past few years the interest of scientists to the rapid radio pulses increased significantly.

“Before this topic, mainly scientists were doing in their free research time,” said Lorimer.

Now, astronomers desperately searching for fast radio pulses in the still unexplored areas of the sky and continue to monitor the sectors of the sky, which was already recorded these phenomena in the hope to register them.

It utilizes the power of telescopes around the world, because the observation of a single pulse of several observatories, the likelihood of a more accurate calculation of the coordinates of the source is significantly increased.

So, in the next few years, radio telescopes, like canadian CHIME (Canadian Hydrogen Intensity Mapping Experiment, or intense Canadian hydrogen mapping experiment), will be able to observe large areas of sky and record hundreds of fast radio pulses.

The more data collected, the more clear will be the phenomenon of fast radio pulses. Maybe someday their secret will be revealed.

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