Related topics: black holes · gamma rays · neutron stars

Fermi spots a supernova's 'fizzled' gamma-ray burst

On Aug. 26, 2020, NASA's Fermi Gamma-ray Space Telescope detected a pulse of high-energy radiation that had been racing toward Earth for nearly half the present age of the universe. Lasting only about a second, it turned ...

Space scientists solve a decades-long gamma-ray burst puzzle

An international team of scientists, led by astrophysicists from the University of Bath in the UK, has measured the magnetic field in a far-off Gamma-Ray Burst, confirming for the first time a decades-long theoretical prediction—that ...

Front-row view reveals exceptional cosmic explosion

Scientists have gained the best view yet of the brightest explosions in the universe: A specialized observatory in Namibia has recorded the most energetic radiation and longest gamma-ray afterglow of a so-called gamma-ray ...

GECAM team reports first detection of gamma-ray transients

In the early morning of Jan. 20 (Beijing Time), the Gravitational Wave High-Energy Electromagnetic Counterpart All-sky Monitor (GECAM or Huairou-1) team reported their first detection of a gamma-ray transient (GRB 210119A) ...

Astronomers unmask cosmic eruptions in nearby galaxies

A brief burst of high-energy light swept through the solar system on April 15, triggering many space-based instruments, including those aboard NASA and European missions. Now, multiple international science teams conclude ...

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Gamma-ray burst

Gamma-ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic explosions in distant galaxies. They are the most luminous electromagnetic events occurring in the universe. Bursts can last from milliseconds to nearly an hour, although a typical burst lasts a few seconds. The initial burst is usually followed by a longer-lived "afterglow" emitting at longer wavelengths (X-ray, ultraviolet, optical, infrared, and radio).

Most observed GRBs are believed to be a narrow beam of intense radiation released during a supernova event, as a rapidly rotating, high-mass star collapses to form a black hole. A subclass of GRBs (the "short" bursts) appear to originate from a different process, possibly the merger of binary neutron stars.

The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10 billion year lifetime) and extremely rare (a few per galaxy per million years). All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way could cause a mass extinction on Earth.

GRBs were first detected in 1967 by the Vela satellites, a series of satellites designed to detect covert nuclear weapons tests. Hundreds of theoretical models were proposed to explain these bursts in the years following their discovery, such as collisions between comets and neutron stars. Little information was available to verify these models until the 1997 detection of the first X-ray and optical afterglows and direct measurement of their redshifts using optical spectroscopy. These discoveries, and subsequent studies of the galaxies and supernovae associated with the bursts, clarified the distance and luminosity of GRBs, definitively placing them in distant galaxies and connecting long GRBs with the deaths of massive stars.

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