We have only had close calls with gamma-ray explosions so big, scientists have suggested that if they happened within our solar area (less than 1,000 lightyears), they could potentially cause mass extinctions.
Reports indicate that there were 440 million years ago NatureA nearby gammaray burst could have killed off much of Earth’s life. Adrian Melott (University of Kansas) and his colleagues believe that the fossil record of Ordovician periods ends fits well with the possibility of a cosmic explosion just a few thousand miles away altering the environment. At that time, more than 100 families of marine invertebrates died out; it was the second most devastating mass extinction in our planet’s history.
GRB Rocks Andromeda
In 2014, telescopes around the world pointed to our neighboring Andromeda Galaxy (above) looking in all wavelengths of light to learn more about a gamma ray burst reported by NASA’s Swift satellite thought to be an explosion from the collision of two neutron stars–the dead cores of massive stars, with the mass of our Sun crushed into the size of a small city.
Neutron Star Collision
These neutron stars meld to create an explosion that can be seen across the Universe. Astronomers think that merging neutron stars in globular clumps of old stars is responsible for up to one third of all short gamma radiation bursts. It blinds galaxies with high energy radiation and decimates nearby worlds.
“Blinding Whole Galaxies, Destroying Millions of Worlds” –Rare Short Gamma Ray Burst Detected
The colliding neutron stars exploded in less than a second (while the optical light can last for a matter of hours before fading) shining out in gamma rays which travelled undisturbed for 2.5 million years until hitting NASA’s Swift satellite, designed to solve the 35-year-old mystery of the origin of gamma-ray bursts, which scientists think are the birth cries of black holes. Within minutes telescopes all around the globe were tracking it, and an hour later, people around the globe were following it via Twitter.
“Typically the Universe moves slowly, with enormous galaxies swirling around in slow motion as measured by human standards and then just occasionally something will go bang and it’s a race against time to record and learn everything you can,” said Alan DuffyWith the Swinburne University Center for Astrophysics.
The GRB titanic explosions produce shock waves that travel at the speed of light into surrounding gas, which glows at radio, optical and x-ray wavelengths. The shocks travel at almost the speed of light, according to the Harvard Center for Astrophysics (CfA), Einstein’s theory of special relativity must be employed in calculating what an observer would see.
”The GRB Appeared as a Small Ring Expanding Faster than the Speed of Light”
“Contrary to common sense,’ says the CfA, the relativistic shock because of gravitational microlensing predicted by Einstein’s theory of general relativity will appear to an observer as a small ring that is expanding faster than the speed of light. The ring will appear small because of the enormous distance to the GRB –equivalent to spotting a wedding ring two million miles away; like seeing an “o” on this page from the Moon.”
“Earth-bound telescopes.” report the CfA, “are limited to about one arcsecond resolution by turbulence in our atmosphere. Better resolution is achieved in space, but the apparent size of the GRB shock is still more than 100000 times smaller than the Hubble Space Telescope resolution of 0.1 arcsecond.”
“The night sky seen in high-energy light is continuously flashing as titanic explosions, bright enough to be seen from across the length of the Universe, erupt and travel to us. It’s a violent world out there,” observed Duffy.
Much Closer to home –An object with a magnetic field one-thousand-trillion times stronger than our Sun’s
It was now April 15, 2020, at 4:42 a.m. U.S. Eastern Time. On that day, a huge flare GRB flew past Mars, signaling itself to satellites and a spacecraft orbiting the planet. It lasted 140 milliseconds.
Soebur Razzaque of the University of Johannesburg, who is the coordinator of the GRB/GW science groups of the Fermi-Large Area Telescope Collaboration (LAT), Collaboration, discovered that the 200415A giant GRB flare was actually from another source of short GRBs, which was also very near to home in cosmic terms. It erupted from a rare, powerful neutron star called a magnetar, a type of young neutron star and the most magnetic objects in the universe, with gravity a billion times Earth’s and a magnetic field one-thousand-trillion times stronger than our Sun’s.
“Cosmic Broadcasts” –Energy Bursts from the Most Powerful Magnetic Fields in the Universe
GRB 200415A was discovered by the Inter Planetary Network (IPN), a group of scientists. It was a result of a magnetic explosion in galaxy NGC253 that occurred about 11.4 million light-years from earth. This galaxy is located near the Sculptor constellation. All the previously known GRB’s were traced to supernovas or two neutron stars spiraling into each other. NGC 253 lies outside our Milky Way home, but is only 11.4 million light-years from us. It is close enough to the nuclear destructive potential of a large GRB flare.
Milky Way Harbors Tens of Thousands of Neutron Stars
GRBs have been detected in the past from faraway galaxies, such as the Milky Way. This one, however, was cosmically closer. “In the Milky Way there are tens of thousands of neutron stars,” says Razzaque. “Of those, only 30 are currently known to be magnetars.
Dark Hearts of the Cosmos –Dazzling New Mergers of Black Holes and Neutron Stars
“Even though gamma-ray bursts explode from a single star, we can detect them from very early in the history of the universe. Even going back to when the universe was a few hundred million years old,” says Razzaque. “That is at an extremely early stage of the evolution of the universe. The stars that died at that time… we are only detecting their gamma-ray bursts now, because light takes time to travel. This means that gamma-ray bursts can tell us more about how the universe expands and evolves over time.”
Source: High-energy emission of a magnetar giant flare in the Sculptor galaxy.Nature Astronomy (2021). DOI: 10.1038/s41550-020-01287-8
The Daily Galaxy Maxwell Moe, astrophysicist, NASA Einstein FellowUniversity of Arizona via Swinburne University of Technology, AAAS/University of Johannesburg, Harvard CfA
Image credit: Shutterstock License Magnetar
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Maxwell Moe is an astrophysicist and NASA Einstein Fellow at the University of Arizona. Max can usually be found at Kitt Peak National Observatory on two nights per week exploring the mysteries and wonders of the Universe. Max earned his Ph.D. in Astronomy in 2015 from Harvard University.
