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The fountain remains silent for about 67 days. Then for about 90 days it wakes up again and emits repeating millisecond radio bursts, then goes silent again. And the whole 157-day cycle repeats itself.
Rapid radio bursts are extremely mysterious, there was no guarantee the cycle would continue. So it is really interesting that the source has recovered again and has done it exactly at the planned time, which is in line with the expected active cycle.
This suggests that it is very important to monitor known sources of high-speed radio bursts, as well as to continue monitoring FRB 121102 to understand what is causing this phenomenon.
Fast radio bursts, as the name suggests, are very short bursts of radio waves that last only a few milliseconds and propagate from galaxies millions or billions of light years away. They are also very powerful: they can emit as much energy as hundreds of millions of suns in those milliseconds.
In most cases these outbursts are unique, we never hear from them again, making it completely impossible to predict and track them. And we don’t know who actually emits them, although recent data provides a solid basis for believing that they are emitted by neutron stars called magnetars.
However, the sources of various high-speed radio flashes have been recorded more than once, they may be one of the keys that help to at least partially solve this puzzle.
Before the astronomer Kaustubh Rajwade and his team from the University of Manchester recorded the aforementioned cycle of flashes, FRB 121102 was already known to be the most active fast radio flash ever detected. Repetitive flashes have been recorded multiple times since its discovery in 2012.
As this outburst repeats, astronomers can monitor its activity and track the galaxy back to its origin. It was the first localized fast radio burst to be associated with the star-forming region in a 3 billion dwarf galaxy. Light years.
The discovery of the periodicity of the activity, based on five years of data, can be quite a significant limitation in terms of what it can be.
For example, high-mass X-ray binary stars in a Milky Way galaxy with neutron stars have orbital periods of up to several hundred days. There are also certain types of binary systems with much shorter periods. They can be rejected in the case of FRB 121102.
And now the periodicity is confirmed by the new observations, although the exact period may still need to be revised.
The team, led by Marilyn Cruces, a researcher at the Max Planck Institute for Radio Astronomy, September and 2020 captured 36 FRB 121102 flashes in June using a 100-meter diameter Efelsberg radio telescope. By combining their research data and that of K. Rajwade, this team determined a 161-day periodicity. She published her findings in a preliminary work that was uploaded to the arXiv portal.
The document indicates the dates of the active period of the source between 2020. July 9 and October 14.
This quick flash of radio is not limited to the Cruces team. A team of scientists led by Pei Wang, a scientist with the China National Astronomical Observatory, used a 500-meter-diameter spherical diaphragm-shaped radio telescope (FAST) to monitor the location of FRB 121102 for several days between March and August this year. .
Between mid-March and the end of July there were no flashes. However, on August 17. this telescope captured at least 12 flashes from FRB 121102, suggesting that the source is back in the active phase, although this command calculated a different periodicity than the Rajwade and Cruces commands.
“We combined the flash data from Rajwade and Cruces, and by linking it to the new FAST data, we got a new periodicity of about 156.1 days,” the Chinese team told The Astronomer’s Telegram.
According to his calculations, the active phase should end between August 31. and September 9. If FRB 121102 remains active after these dates, it will be possible to assume that the periodicity is false or changes in some way.
Of course, it may be necessary to adjust the periodicity calculations, which means that researchers must continue to monitor FRB 121102.
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