So far, we’ve only had close calls of gamma-ray bursts so large, scientists have suggested, that if they occur in our solar neighborhood (less than 1,000 light-years away), they could potentially trigger mass extinctions on Earth.
Some 440 million years ago, reports Nature, a nearby gamma-ray burst may have extinguished much of life on Earth. University of Kansas astrophysicist Adrian Melott and his colleagues hypothesize that the fossil record from the late Ordovician period matches how such a cosmic explosion a few thousand light-years away might have been. change the environment. At that time, more than 100 families of marine invertebrates became extinct; it was the second most devastating mass extinction in the history of our planet.
Cosmos at the bottom of the sea
GRB Rocks Andromeda
In 2014, telescopes around the world pointed to our neighboring galaxy Andromeda (above) looking into all wavelengths of light to learn more about a gamma-ray burst reported by NASA’s Swift satellite, thought to be an explosion due to the collision of two neutron stars – the dead cores of massive stars, with the mass of our Sun squashed into the size of a small town.
Neutron star collision
When these neutron stars merge, the explosion is so powerful that it can be seen from anywhere in the Universe. Astronomers suspect that up to a third of all short gamma-ray bursts come from neutron stars merging into globular clusters of old stars, blinding entire galaxies with high-energy radiation and destroying neighboring worlds.
“Blinding Entire Galaxies, Destroying Millions of Worlds” – Rare Short Gamma Ray Burst Detected
The colliding neutron stars exploded in less than a second (whereas optical light can last hours before fading) glowing in gamma rays that traveled undisturbed for 2.5 million years until until they hit NASA’s Swift satellite, designed to solve the 35-year-old mystery of the origin of gamma-ray bursts, which scientists believe are the birth cries of black holes. Within minutes telescopes around the world were following him and an hour later people around the world were following him on Twitter.
“Usually the Universe moves slowly, with huge galaxies whirling around in slow motion by human standards, and then every once in a while something happens and it’s a race against time to record and learn everything you can,” said Alan Duffy of Swinburne University. Astrophysics Center.
The titanic GRB explosions create shock waves that travel at near the speed of light through the surrounding gas which then glows at X-ray, optical, and radio wavelengths. Because shocks travel almost at the speed of light, reported the Harvard Center for Astrophysics (CfA)Einstein’s special theory of relativity must be used to calculate 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 due to gravitational microlensing predicted by Einstein’s theory of general relativity will appear to an observer as a small ring that expands faster than the speed of light. The ring will appear small due to the huge distance between it and the GRB, which is equivalent to spotting an alliance two million miles away; like seeing an “o” on this page from the Moon.
“Terrestrial 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 100,000 times greater. smaller than the Hubble Space Telescope’s resolution of 0.1 arcseconds.
“The night sky seen in high-energy light is constantly flashing as titanic explosions, bright enough to be seen from the length of the Universe, erupt and travel towards us. It’s a violent world out there. -down,” Duffy observed.
Much closer to home – An object with a magnetic field a trillion times stronger than that of our Sun
Fast forward to 4:42 a.m. EST on April 15, 2020, when a giant GRB flare swept through Mars, announcing itself to satellites, a spacecraft, and the International Space Station orbiting our planet. And it only lasted 140 milliseconds, about the blink of an eye.
A research team from the University of Johannesburg led by Soebur Razzaque, coordinator of the GRB and GW science group of the Fermi-Large Area Telescope (LAT) collaboration, has revealed that this giant GRB flare, 200415A, came from another source possible for short GRB which was also very close to home, in cosmic terms. It erupted from a rare and powerful neutron star called a magnetar, a type of young neutron star and the most magnetic objects in the universe, with gravity one billion times that of Earth and a magnetic field trillion times stronger than that of our Sun.
“Cosmic Emissions” – Bursts of energy from the strongest magnetic fields in the universe
The Inter Planetary Network (IPN), a consortium of scientists, discovered that GRB 200415A exploded from a magnetar in the galaxy NGC 253 about 11.4 million light-years from Earth in the constellation Sculptor. All previously known GRBs have been attributed to supernovae or two neutron stars spiraling into each other. NGC 253 is outside our home, the Milky Way, but it’s only 11.4 million light-years away. It’s relatively close when talking about the destructive nuclear power of a giant GRB eruption.
The Milky Way is home to tens of thousands of neutron stars
Previously detected GRBs came from relatively far away from our home galaxy, the Milky Way. But this one came from much closer to home, in cosmic terms. “In the Milky Way, there are tens of thousands of neutron stars,” says Razzaque. “Of these, 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 very early in the history of the universe. Even going back to when the universe was a few hundred million years old” “, explains Razzaque. “It’s at an extremely early stage in the evolution of the universe. Stars that died at that time… we only detect their gamma-ray bursts now, because light takes a long 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 from a giant magnetar flare in the Sculptor Galaxy. Natural Astronomy (2021). DOI: 10.1038/s41550-020-01287-8
The Daily Galaxy, Maxwell Moeastrophysicist, NASA Einstein FellowUniversity of Arizona, via Swinburne University of Technology, AAAS/University of Johannesburg, Harvard Cfa
Image credit: Magnetar, Shutterstock license
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Maxwell Moe, astrophysicist, NASA Einstein Fellow, University of Arizona. Max can be found two nights a week probing the mysteries of the universe at Kitt Peak National Observatory. Max received his doctorate in astronomy from Harvard University in 2015.
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