It could be the most powerful explosion ever recorded

It could be the most powerful explosion ever recorded

On October 9, several observatories detected a powerful burst of gamma rays passing through our solar system. Dubbed GRB 221009A, it would be the most powerful ever recorded. The origin of this big explosion: probably the “birth cry” of a new black hole.

If the Universe seems very dark to us at first glance, it is actually bathed in light. And sometimes these lights can reach intensities beyond comprehension. Gamma-ray bursts, in particular, are among the brightest events known. These extremely high-energy bursts, which last from a few milliseconds to several hours, can have various origins.

What are gamma ray bursts?

The first outbursts were observed in the late 1960s by the American Vela satellites. These were supposed to detect gamma ray signatures indicative of nuclear weapons tests. The United States feared that the Soviets were secretly conducting tests despite a ban treaty signed in 1963. Over the next few years, Vela satellites equipped with improved instruments have recorded other bursts, prompting scientists to further investigate their origins.

In the early 1970s, a team at Los Alamos National Laboratory analyzed when different satellites detected each burst to estimate the position in the sky of sixteen of them. It was later determined that these events did not originate on Earth, or even in our solar system. But what is it, precisely?

Now we know there is two classes gamma ray bursts. Most of them (about two-thirds) are longer than two seconds, often with a bright afterglow. These events usually take place in rapidly star-forming galaxies. Specifically, these long bursts would be linked to the death of massive stars becoming neutron stars or black holes. The formation process of these objects would produce jets of highly energetic particles moving at almost the speed of light, emitting X-rays and gamma rays.

The other gamma-ray bursts last less than two seconds. These events are the result of mergers between two neutron stars, or a neutron star with a black hole.

The most powerful ever detected

This latest gamma-ray burst belongs to the first category. baptized GRB221009A, was discovered on October 9 by detectors from the Fermi Gamma-ray Space Telescope, the Neil Gehrels Swift Observatory, and the Wind spacecraft, among others. We know that this event happened around 1.9 billion light years from Earth, toward the constellation Sagittarius. Furthermore, the explosion would have lasted more than ten hours.

gamma ray burst
Credit: International Gemini Observatory/NOIRLab/NSF/AURA/B. O’Connor (UMD/GWU)
gamma ray burst
Images taken in visible light by the Swift Optical/Ultraviolet Telescope. The glow fades in about ten hours. Credit: NASA/Swift/B. cenko

In addition to being exceptionally long, it is the brightest gamma-ray burst ever recorded. ” Its radiance breaks all records in all wavelengths“said Brendan O’Connor of the University of Maryland.” Because this outburst is so bright and so “close,” we believe this is a once-in-a-century opportunity to address some of the most fundamental questions about these outbursts, from the formation of black holes to testing models of matter.“.

If this event can be considered “close” by the astronomer, however, it remains far enough away that it does not threaten Earth. A gamma-ray burst generated less than 5,000 to 8,000 light-years from our planet, on the other hand, would do a lot of damage. There would likely be a short-term increase in ultraviolet radiation levels in the soil, leading to a sharp increase in DNA damage to living organisms. Some have even suggested that the Ordovician-Silurian extinction event around 450 million years ago could have been the result of one of these outbursts. However, the hypothesis is still widely debated.

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