The emission time of the radio wave is only 0.3 microseconds!Detecting a “ultra-fast radio wave burst” beyond a high-speed radio wave burst | sorae space portal website

“Emits a large amount of radio waves in a short period of time.”High-speed radio explosionThere are many mysteries surrounding FRBs (fast radio bursts), such as their true nature and mechanism, and research is still ongoing.

A research team led by MP Snelders from ASTRON (Netherlands Institute for Radio Astronomy) discovered fast radio bursts, the only periodic emission of radio waves ever observed.FRB 20121102AAs a result of checking monitoring dataThe emission time of the radio wave is 0.3 to 4 microsecondsIt was revealed that eight microsecond bursts (1 microsecond = 1 millionth of a second) were observed. This lasts less than one-tenth the time of conventional high-speed radio bursts.Ultrafast radio wave explosionThis is the first observation of “ultrafast radio bursts” and will provide important clues to clarify the mechanism of high-speed radio bursts.

■ What is a high-speed radio wave burst?

“Fast radio bursts”, which emit powerful radio waves for a short period of time, are high-energy astronomical phenomena that were only discovered in 2007. As the name suggests, a high-speed radio burst is an astronomical phenomenon that emits radio waves, but although… Radio waves are emitted for less than one second, the amount of energy is comparable to the total energy emitted by the Sun over several days. With one exception, fast radio bursts are non-periodic astronomical phenomena that are observed only once.

Based on the properties of observed radio waves, high-speed radio bursts are thought to be emitted by celestial bodies with strong magnetic fields, such as neutron stars, but the exact nature and mechanism of their generation are largely unknown. This is possible because most high-speed radio burst emission times are on the order of milliseconds (1 millisecond = 1/1000th of a second), and the source of the radio wave emission is estimated to be located less than a few hundred kilometers away. .

Radio waves are also expected to be emitted for shorter periods of time, specifically on the microsecond scale. However, this has been difficult to observe due to limitations in the observation resolution of radio telescopes and the modulation of radio waves due to the effects of thin matter particles in space. For this reason, microsecond-scale radio wave emissions have so far been observed as subbursts accompanying the main explosion, but never as an isolated explosion.

■“Ultrafast radio burst” first detected in FRB 20121102A

We mentioned in the previous chapter that high-speed radio bursts are non-periodic astronomical phenomena with one exception.FRB 20121102A“FRB 20121102A, located in the constellation Auriga as seen from Earth, was successfully detected several times by independent observation teams several years later. It has now been revealed that radio waves are emitted several dozen times per hour, making FRB 20121102A one of the The most interesting observation targets among high-speed radio bursts.

Snelders and his team conducted the analysis using 5 hours of observational data for FRB 20121102A collected on August 26, 2017 by the Robert Byrd Green Bank Telescope in West Virginia, USA. For the first 30 minutes of the five-hour period, the data was divided into 1/500,000 per second, then analyzed using software and machine learning to determine if there was any unusual data.

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As a result, the emission time of the radio wave is 0.3 to 4 microseconds.Contains 8 isolated bursts of less than 30 microseconds in durationI’ve discovered it. This results in a burst that lasts less than one-tenth of a normal high-speed radio burst. In previous research, Snelders et al.Ultrafast radio wave explosion“, but this is the first time this has actually been observed.

Interestingly, although the duration of ultrafast radio bursts is very short, the properties of radio waves are similar to much longer bursts. This result indicates that high-speed radio wave bursts and ultra-fast radio wave bursts are emitted by a similar mechanism, and is an important piece of evidence in clarifying the mechanism by which high-speed radio wave bursts are emitted.

■ Are there other ultra-fast bursts of radio waves?

Snelders and his team believe that other ultrafast radio bursts have been detected. For example, in a study that predicted the existence of ultrafast radio bursts,FRB 20200120EIt is expected to last for only 60 nanoseconds (0.06 microsecond, where 1 nanosecond is a billionth of a second). However, many observational data for high-speed radio bursts, including FRB 20200120E, do not have sufficient precise observational data to prove this.

It is known that the radio waves of fast radio bursts are affected by the high-temperature ionized gas that thinly fills the space between galaxies, so studying the distribution of fast radio bursts is useful for studying the global structure of the universe, but it is important. In the course of this research, new ultrafast radio bursts could also be discovered.

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Written by Riri Aya