Eruption from an object with a magnetic field a trillion times stronger than that of our sun


So far, we’ve only had close calls from gamma-ray bursts so large, the scientists have suggested, that if they occurred within our solar neighborhood (less than 1,000 light-years away) they could potentially trigger mass extinctions on Earth.

About 440 million years ago, reports Nature, a nearby gamma-ray burst may have wiped out much of life on Earth. University of Kansas astrophysicist Adrian Melott and colleagues speculate that the fossil record from the late Ordovician period matches how such a cosmic explosion a few thousand light-years away could have altered 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 Andromeda Rock

In 2014, telescopes around the world turned to our neighboring Andromeda Galaxy (top) looking at all wavelengths of light to learn more about a gamma-ray burst reported by NASA’s Swift satellite, believed to be a explosion from the collision of two neutron stars: the dead stars cores of massive stars, with the mass of our Sun squeezed to the size of a small city.

Collision of neutron stars

When these neutron stars merge, the explosion is so powerful that it can be seen from all over the Universe. Astronomers suspect that up to a third of all short gamma-ray bursts come from the merger of neutron stars in globular clusters of old stars, blinding entire galaxies with high-energy radiation and destroying nearby worlds.

“Blinding entire galaxies, destroying millions of worlds” – Rare burst of short gamma rays detected

The colliding neutron stars exploded in less than a second (whereas optical light can last a few hours before fading away) shining with gamma rays that traveled undisturbed for 2.5 million years until they hit NASA’s Swift satellite. designed to solve the 35-year-old problem. -ancient mystery of the origin of gamma-ray bursts, which scientists think are the birth cries of black holes. Within minutes, telescopes from all over the world were following him and an hour later people from all over the world were following him on Twitter.

“Typically the Universe moves slowly, with huge galaxies spinning in slow motion by human standards and then just occasionally something explodes and it’s a race against time to record and learn everything you can,” said Alan Duffy of Swinburne University Astrophysics Center.

GRB’s titanic explosions create shock waves that travel at near the speed of light in the surrounding gas, which then glows in X-ray, optical, and radio wavelengths. Because the aftershocks are moving almost at the speed of light, reported the Harvard Astrophysics Center (CfA)Einstein’s special theory of relativity must be employed 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 is expanding faster than the speed of light. The ring will appear small due to the enormous distance from the GRB, equivalent to spotting a wedding ring two million miles away; how to see an “o” on this page from the Moon.

“Earth-Bound Telescopes”. reports the CfA, “are limited to about one arc-second resolution by the turbulence in our atmosphere. In space you get better resolution, but the apparent size of the GRB shock is still more than 100,000 times smaller than the Hubble Space Telescope’s resolution of 0.1 arcsecond.

“The night sky seen in high-energy light flashes continuously as titanic explosions, bright enough to be seen from the entire length of the Universe, explode and travel towards us. It’s a violent world out there,” Duffy noted.

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. Eastern Time on April 15, 2020, as a giant GRB flare passed 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 flare GRB, 200415A, came from another possible source in short GRB that was also very close to home, in cosmic terms. It is erupted by a rare and powerful neutron star called a magnetar, a type of young neutron star and the most magnetic objects in the universe, with Earth’s gravity a billion times stronger and a magnetic field a trillion times stronger than that of Earth. our sun.

“Cosmic Broadcasts” – Bursts of energy from the strongest magnetic fields in the Universe

The Inter Planetary Network (IPN), a consortium of scientists, has discovered that GRB 200415A erupted from a magnetar in the galaxy NGC 253 about 11.4 million light-years from Earth towards the constellation Sculptor. All previously known GRBs have been traced to supernovae or two neutron stars spiraling into each other. NGC 253 is located outside our home, the Milky Way, but is only 11.4 million light-years away from us. This is relatively close when talking about the nuclear destructive power of a giant GRB flare.

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 was much closer to home, cosmically speaking. “There are tens of thousands of neutron stars in the Milky Way,” says Razzaque. “Of these, only 30 are currently known to be magnetars.

Dark Hearts of the Cosmos – Amazing new mergers of black holes and neutron stars

“Even if gamma-ray bursts explode from a single star, we can detect them from the very beginning of the universe’s history. Even going back to when the universe was a few hundred million years old,” Razzaque says. “This is at an extremely early stage in the evolution of the universe. gamma-ray bursts, 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 from a giant magnetar flare in the Sculptor galaxy. Astronomy of Nature (2021). DOI: 10.1038/s41550-020-01287-8

The Everyday Galaxy, Maxwell Moastrophysicist, NASA Einstein FellowUniversity of Arizona, via Swinburne University of Technology, AAAS/University of Johannesburg, Harvard CF

Image Credit: Magnetar, Licensed by Shutterstock

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