Fast radio burst

Bright flashes of light flash in space.

These flashes are called fast radio bursts. They happen very quickly. Some last only a tiny part of a second.

These bursts have a lot of power. One burst can have as much energy as our sun makes in three days. Most of these flashes come from far away in space. Some come from stars called magnetars. Scientists are still learning why they happen. It is a big mystery of the sky.

Space sometimes sends us quick flashes of radio waves. We call these fast radio bursts, or FRBs for short.

These bursts are very brief. Some last only a tiny part of a second. Others can last up to three seconds.

FRBs have a lot of power. One burst can let out as much energy as the Sun makes in three days. Even so, the signal is hard to hear. By the time it reaches Earth, it is very weak.

Most FRBs come from far away in other galaxies. But in 2020, scientists found one inside our own Milky Way. They think a magnetar might cause them. A magnetar is a type of star with a very strong magnetic field.

Some FRBs are repeaters. This means they flash more than once. One special burst, called FRB 180916, pulses every 16.35 days. Scientists are still studying these flashes to find out exactly what makes them happen.

Fast radio bursts, or FRBs, are sudden flashes of radio waves from deep space.

These bursts are very quick. Some last only a tiny part of a millisecond. Others can last for up to three seconds. They are extremely energetic events. One single millisecond burst can release as much energy as our Sun makes in three days. Even with all that power, the signal is hard to find. By the time it reaches Earth, it is 1,000 times weaker than a mobile phone signal on the Moon.

Scientists are still learning how these bursts work. The signal often looks like a single spike of energy. As the waves travel through space, they hit free electrons. This causes a delay called dispersion. This means different parts of the radio wave arrive at different times. The signal appears to sweep rapidly down in frequency.

This happens because longer wavelengths are delayed more than shorter ones. Some bursts are also polarized. This means they come from a place with an extremely powerful magnetic field.

We first found these bursts by looking at old data. Duncan Lorimer and David Narkevic discovered the first one in 2007. They called it the Lorimer burst. It was found in data recorded by the Parkes Observatory in 2001. In 2015, scientists saw a burst happen live for the first time. Since then, many more have been found. The CHIME radio telescope has found many since 2018.

In June 2021, astronomers reported over 500 bursts from outer space in just one year.

Most FRBs come from other galaxies far away. For a long time, we did not see any in our own Milky Way. That changed in April 2020 when CHIME found the first one here. This burst came from a magnetar named SGR 1935+2154. A magnetar is a star with a very strong magnetic field.

Some FRBs repeat, meaning they flash more than once. FRB 180916 is a special one that pulses every 16.35 days. Other repeaters, like FRB 121102, come from galaxies billions of light-years away.

There are many ideas about what causes these flashes. Some scientists think they come from colliding black holes or neutron stars. Others suggest they might come from magnetars or even exploding stars called supernovae. Some even wondered if they could be signs of extraterrestrial intelligence. This is similar to when the first pulsar was found. Back then, people joked the signals came from "little green men." Today, researchers use big telescopes to find the exact home of each burst.

Fast radio bursts, or FRBs, are sudden, intense flashes of radio waves from deep space.

These transient signals are extremely brief in duration. Some last for only a fraction of a millisecond. Others can last for as long as three seconds. Despite their short lives, they are incredibly energetic. Astronomers estimate that a single millisecond of an FRB releases as much energy as our Sun produces in three days. Even with this massive power, the signal is very faint by the time it reaches us. The strength of a signal reaching Earth is about 1,000 times less than a mobile phone signal on the Moon.

When astronomers observe these bursts, they notice a specific pattern in the radio waves. The signal often appears as a single spike of energy. As these waves travel through the ionized plasma of space, they encounter free electrons. This interaction creates a delay called a dispersion measure (DM). This delay causes the different frequencies of the burst to arrive at different times. Specifically, the longer wavelengths are delayed more than the shorter ones. Because of this, the received signal appears to sweep rapidly down in frequency.

Additionally, some bursts are polarized. This polarization indicates the signal was emitted from a source within an extremely powerful magnetic field.

Scientists categorize FRBs based on how they behave over time. Most FRBs are non-repeating, meaning they appear as a single, isolated event. However, several repeating FRBs have been detected. Some repeat in seemingly irregular ways, while others follow a strict schedule. For example, FRB 180916 is unique because it appears to pulse every 16.35 days. There is also a distinction between where these bursts originate. Most FRBs are extragalactic, meaning they come from other galaxies. However, the CHIME radio telescope detected the first Milky Way FRB in April 2020.

The history of FRB discovery began with archival research. In 2007, Duncan Lorimer and his student David Narkevic discovered the first FRB. They found it while looking through old pulsar survey data from the Parkes Observatory. This first event is often called the Lorimer burst. In 2015, astronomers reported the first time an FRB was observed live. Since the CHIME telescope became operational in 2018, many more have been found in real time. In June 2021, astronomers reported that over 500 FRBs had been detected from outer space in a single year.

Locating the source of an FRB is a major scientific challenge. Astronomers use the distance and environment of a host galaxy to understand them. For instance, FRB 121102 was identified in 2017 as a repeating source. It is located in a galaxy about three billion light-years away. This source is embedded in an extreme environment. In contrast, the first host galaxy found for a non-repeating burst was FRB 180924. This burst came from a much larger, more ordinary galaxy nearly the size of the Milky Way.

In 2025, astronomers even found FRBs from a galaxy 2 billion light-years away that was thought to be dead.

There are many competing hypotheses regarding the cause of these bursts. One leading theory involves magnetars, which are neutron stars with massive magnetic fields. In 2020, a burst called FRB 200428 was detected near the magnetar SGR 1935+2154. This discovery helped establish magnetars as a plausible source. Other theories suggest the bursts come from compact-object mergers, such as colliding black holes or neutron stars. Some scientists have even proposed more exotic ideas. These include cosmic strings, the collapse of pulsars due to dark matter, or even signals from extraterrestrial intelligence. This last idea is similar to when the first pulsar was nicknamed "LGM-1" for "little green men."

Modern research is now looking into the specific plasma processes that drive these emissions. One promising mechanism is coherent electromagnetic emission from relativistic magnetized shocks. These shocks might occur when magnetar flares drive outflows into a plasma. Another possibility is the electron cyclotron maser instability (ECMI). This process could be triggered when radiative losses sustain coherent radio emission in strongly magnetized plasmas. Recent studies of FRB20201124A also suggest a binary system with a high accretion rate. This system might blow a plasma bubble in a star-forming region, creating persistent radio emission. By studying these complex systems, scientists hope to finally solve the mystery of the fast radio burst.