Explained: What is a radio burst, spotted by NASA for the first time in the Milky Way?        Â
Context: NASA has reported that, it observed a mix of X-ray and radio signals never observed before in the Milky Way.
- Significantly, the flare-up it observed included the first fast radio burst (FRB) seen within the galaxy.
Who discovered the simultaneous bursts in the Milky Way?
- The X-ray portion of the simultaneous bursts was detected by several satellites, including NASA’s Wind mission.
- The radio component was discovered by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope located at Dominion Radio Astrophysical Observatory in British Columbia
- A NASA-funded project called Survey for Transient Astronomical Radio Emission 2 (STARE2) also detected the radio burst seen by CHIME.
So what is an FRB?
- The first FRB was discovered in 2007, since when scientists have been working towards finding the source of their origin.
- FRBs are bright bursts of radio waves (radio waves can be produced by astronomical objects with changing magnetic fields) whose durations lie in the millisecond-scale, because of which it is difficult to detect them and determine their position in the sky.
What is the origin of the FRB detected in April?
- The source of the FRB detected in April in the Milky Way is a very powerful magnetic neutron star, referred to as a magnetar, called SGR 1935+2154 or SGR 1935.
- It is located in the constellation Vulpecula and is estimated to be between 14,000-41,000 light-years away.
- The FRB was part of one of the magnetar’s most prolific flare-ups, with the X-ray bursts lasting less than a second.
- The radio burst, on the other hand, lasted for a thousandth of a second and was thousands of times brighter than any other radio emissions from magnetars seen in the Milky Way previously.
- It is possible that the FRB-associated burst was exceptional because it likely occurred at or close to the magnetar’s magnetic pole.
- This flare-up, which lasted for hours, was picked up by NASA’s Fermi Gamma-ray Space telescope and NASA’s Neutron star Interior Composition Explorer (NICER), which is an X-ray telescope mounted on the International Space Station.
What is a magnetar?
- A magnetar is a neutron star, “the crushed, city-size remains of a star many times more massive than our Sun.”
- The magnetic field of such a star is very powerful, which can be over 10 trillion times stronger than a refrigerator magnet and up to a thousand times stronger than a typical neutron star’s.
- Neutron stars are formed when the core of a massive star undergoes gravitational collapse when it reaches the end of its life.
- This results in the matter being so tightly packed that even a sugar-cube sized amount of material taken from such a star weighs more than 1 billion tons.
- Magnetars are a subclass of these neutrons and occasionally release flares with more energy in a fraction of a second than the Sun is capable of emitting in tens of thousands of years.
- In the case of SGR 1935, the X-ray portion of the simultaneous bursts it released in April carried as much energy as the Sun produces in a month, assuming that the magnetar lies towards the nearer end of its distance range.
Why is this observation significant?
- Until now, there were various theories that tried to explain what the possible sources of an FRB could be.
- One of the sources proposed by the theories has been magnetars.
- But before April this year, scientists did not have any evidence to show that FRBs could be blasted out of a magnetar. Therefore, the observation is especially significant.
1.png)
