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Current Affairs

Radio burst in Milky Way

Date: 07 November 2020 Tags: Space

Issue

NASA has reported that it observed a mix of X-ray and radio signals never observed before in the Milky Way.

 

Background

The flare-up observed by NASA included the first fast radio burst (FRB) seen within the Milky Way galaxy.

 

Details

  • FRBs are bright bursts of radio waves whose durations lie in the millisecond-scale, because of which it is difficult to detect them and determine their position in the sky.

  • The X-ray portion of the simultaneous bursts was detected by several satellites, including NASA’s Wind mission, and the radio component was discovered by the Canadian Hydrogen Intensity Mapping Experiment (CHIME).

  • A NASA-funded project called Survey for Transient Astronomical Radio Emission 2 (STARE2) also detected the radio burst seen by CHIME.

  • 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, which 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 significant flare-ups, with the X-ray bursts lasting less than a second.

  • It is possible that the FRB-associated burst was exceptional because it likely occurred at or close to the magnetar’s magnetic pole.

 

Magnetar

  • A magnetar is a neutron star, the crushed, large 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.

  • 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.

 

Neutron star

Neutron stars are created when giant stars die in supernovas and their cores collapse, with the protons and electrons essentially melting into each other to form neutrons.

 

Significance

  • 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.