Monday, August 15, 2022

A strange fast radio explosion from 3 billion light-years away

There is still much to be discovered in the mysterious vastness of the universe, from ice volcanoes to star-sucking black holes. Now, an international team of astronomers has discovered what is believed to be the only second example of a special type of repetitive fast radio bursts (or FRBs for short).

This new discovery prompts questions about what types of celestial objects might be potential sources for these rapidly repeating radio waves, as well as how useful these sources might be in various astronomical calculations.

The team’s findings, which were published in the journal NatureDetail how researchers were able to identify the new fast radio burst, which they named FRB 190520, using two of the world’s most powerful radio telescopes.

The team’s paper also points to compelling evidence that indicates there may be more than one source behind these mysterious emissions, which they believe may be caused by a dwarf galaxy about 3 billion light-years away from Earth. is located in.

Fast radio bursts are radio pulses ranging in length from a fraction of a millisecond to a few milliseconds. Although scientists do not yet fully understand the astronomical processes behind FRBs, these high-intensity radio pulses can release an average of as much energy in one millisecond as the Sun will emit in three days. But it is hard to pinpoint the exact source or sources of these energetic explosions, due to the fact that FRBs often erupt only once and in distant galaxies.

Mysterious explosion of radio waves

The first rapid radio bursts were detected in 2007, while scientists were combing through archival pulsar survey data. As recently as 2020, scientists detected an FRB within our local galaxy that originated from a special type of rapidly spinning and highly magnetized neutron star called a magnetar. These extremely dense objects are the remains of a star that has gone supernova, and are characterized by a powerful magnetic field that exerts a force trillions of times greater than that of Earth.

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But what appears to be even more rare are repeat FRBs. In 2016, astronomers identified FRB 121102, an actively replicating FRB in a dwarf galaxy 3 billion light-years away, originating from a local region and from an unknown source. At the time, astronomers believed that FRB 121102 was a unique event, as it followed a strange pattern where it emitted more powerful, faster radio waves, then a weak discharge 67 days later. passes by.

High-intensity high-intensity radio pulses can release as much energy in one millisecond as the Sun will emit in three days.

But that all changed with this most recent discovery. Similar to FRB 121102, FRB 190520 exhibits similar peculiar behavior of cyclic periods of strong and weak emissions, which were confirmed using China’s 500 m Aperture Spherical Radio Telescope (FAST). In addition, the location of FRB 190520 in a dwarf galaxy about 3 billion light-years away was later discovered by Carl G. of the National Science Foundation in New Mexico. was determined using the Jansky Very Large Array (VLA). These latest observations prompted the research team to consider whether there might be different types of FRBs.

“Are those that repeat any different from those that don’t? What about persistent radio emissions – is this common?” Study co-author and West Virginia University graduate student Kshitij Agarwal said in a statement.

FRB 190520 . Optical, infrared and radio images of the region of

Now, astronomers are suggesting that there may be different mechanisms that aid in the production of FRBs, or perhaps that the sources of FRBs behave differently during different stages of their lifespan. For example, it may happen that after a supernova explosion of a massive star, the resulting ultra-dense neutron stars become sources of FRBs. Alternatively, extremely magnetic versions of neutron stars or magnetars could also be major sources of these mysterious radio bursts.

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Furthermore, the team’s findings are also casting into doubt whether the FRB can be reliably used as a tool to perform astronomical calculations. Scientists often determine how far an object can travel by measuring how much FRB’s radio emissions are filtered by frequency, with higher frequency waves traveling faster than lower frequencies.

This effect, called dispersion, depends on what type of gaseous material the radio waves have to pass through, and can usually help experts gauge how far the object is from Earth.

Surprisingly, this method did not work for FRB 190520. Accounting for the Doppler shift, or how radio wavelengths are spread out in relation to the expansion of the universe, the team was able to determine that the source of FRB 190520 lies. Only 3 billion light-years away, instead of the 8 or 9 billion light-years that the apparent signal dispersion may have initially indicated.

“This means that the FRB has a lot of material that would confound any attempt to use it to measure gas between galaxies,” Agarwal explained. “If this is the case with others, we cannot count on using FRBs as cosmic yardsticks.”

The team now believes that the source of FRB 190520 may be a newly formed magnetar, as evidenced by the strikingly dense electron clouds surrounding FRB 190520. These dense clouds will dissipate over time, leading to a reduction in active bursts from FRB 190520. In any case, the researchers plan to continue their investigations on this FRB and others in the future in hopes of discovering more clues about this interesting celestial mystery.

Read more in the team’s paper.

Images: Igor Mashkov via Pexels; West Virginia University, Chinese Academy of Sciences, Cornell University, Caltech, University of Tokyo, Max Planck Institute, Western Sydney University, CSIRO Space and Astronomy, Peking University, Chinese Academy of Sciences University, University of Nevada

Nation World News Desk
Nation World News Desk
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