Gamma Ray Bursts (GRBs)
Gamma-Ray Bursts are incredibly powerful explosions that burst forth from distant galaxies. They represent the most luminous electromagnetic events in the universe in terms of release of pure energy.
Key Characteristics
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Duration - Bursts generally last between a few milliseconds and several minutes.
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Energy - In a few seconds, they emit an amount of energy equal to what our Sun will emit in its whole lifetime that has been predicted to exceed 10 billion years.
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Wavelength: As the name itself indicates, they emit mainly gamma rays, which are of the highest energy among the electromagnetic radiation.
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Afterglow: In events that follow the burst, GRBs are usually followed by an afterglow in X-ray, ultraviolet, optical, infrared, and radio wavelengths.
If a Gamma Ray Burst directed towards us happens in the Milky Way, it will lead to the extinction of life on Earth.
Origins
The generally assumed origins of GRBs are from two major sources :
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Core-collapse of massive stars: long-duration GRBs- greater than 2 seconds in length-arise from the collapse of very massive stars into black holes: A hypernova or collapsar is a supernova resulting in a black hole when the core of a massive star directly collapses into one.
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Mergers of compact objects: short bursts (< 2 s) likely arise from mergers of neutron stars or black holes and neutron stars. Now, these sources have also been detected to emit gravitational waves by the observation of GW170817 in 2017.
GRBs are usually detected by space-based observatories, such as the NASA Swift and Fermi satellites. When a GRB is detected, its position is quickly broadcast to ground-based telescopes, which make follow-up observations of the afterglow.
GRBs allow insight into high-energy astrophysics, the formation of black holes, and the early universe. They can be detected from incredibly far distances, making them excellent probes of the cosmos across vast stretches of space and time.