Since the initial discovery of the fast radio burst (FR) about 15 years ago, they have remained enigmatic to scientists. This cosmic explosion is an intense burst of radio energy that lasts only milliseconds but emits as much energy as the Sun does in a few days.
A recent study conducted by an international team of researchers focused on FRB 20190520B, which originates from a dwarf galaxy located approximately four billion light-years away from Earth. The team has concluded that the most likely source of this specific burst is a dense object, potentially a neutron star, accompanied by a binary companion.
This artist’s impression represents the path of the fast radio burst FRB 181112 traveling from a distant host galaxy to reach the Earth. FRB 181112 was pinpointed by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. Follow-up observations with ESO’s Very Large Telescope (VLT) revealed that the radio pulses have passed through the halo of a massive galaxy on their way toward Earth. This finding allowed astronomers to analyse the radio signal for clues about the nature of the halo gas.
Repeating Fast Radio Burst an Ideal Target for Long-Term Study
FRB 20190520B stands out among other fast radio bursts (FRBs) due to its unique characteristic as a "repeater," continuously emitting bursts across different radio frequencies. This makes it an excellent subject for long-term study.
According to Science Alert, the majority of FRBs are brief and isolated events originating from outside our own Milky Way galaxy. However, the exact cause and nature of most FRBs remain unknown.
The repeating burst, FRB 20190520B, was initially detected in 2022 by astronomers at China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST). While repeating FRBs are already uncommon, FRB 20190520B is even rarer as it constantly produces radio bursts multiple times per hour, sometimes across various radio frequencies.
Following its discovery, astronomers quickly conducted further investigations using different radio wavelengths. These studies revealed that FRB 20190520B exists within an extremely dense environment located in a dwarf galaxy situated approximately 3.9 billion light-years away. Additionally, there are surrounding materials near the source of FRB emissions that generate strong and continuous radio signals.
These findings have led to hypotheses suggesting that the source of the bursts could be a young neutron star located in a complex environment.
FRB Surrounded With Highly Changeable Magnetic Field
The research team closely monitored FRB 20190520B using the Parkes Radio Telescope in Australia and the Robert C. Byrd Green Bank Telescope in the United States for 17 months, Space.com reported.
They observed significant fluctuations in the Faraday rotation of the FRB, indicating a highly turbulent magnetic environment surrounding the source. This variability led the team to propose that the changes are caused by wind from a massive companion star in a binary system, a hypothesis supported by a similar system within the Milky Way.
The team explored alternative explanations, such as the FRB passing through waves from a supernova or being in the vicinity of a massive black hole, both of which could result in the observed Faraday rotation variations. However, the binary system theory presented the strongest evidence.
While most FRBs do not exhibit repeating behavior like FRB 20190520B, they share similar energy scales, narrow-band emissions, and temporal widths. Investigating the origin of FRB 20190520B may offer insights into understanding the origins of other FRBs as well.
Continuous monitoring of various observed properties of repeating FRBs, such as their dispersion measure and Faraday rotation measure, could provide valuable clues in unraveling this mystery.
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