Astronomers Just Found a Monstrous Cosmic Explosion in the Last Place They Expected

Most gamma ray bursts (the brightest and most powerful explosions in the universe) are It dates back to the death of massive stars.. But a new discovery suggests that such huge explosions can come from surprisingly small galaxies, if conditions align for particularly dense stars.

In 2023, astronomers using NASA’s Chandra X-ray Observatory and Hubble Space Telescope detected an unusual class of short gamma-ray bursts, the origin of which appeared to be the collision of two neutron stars. Follow-up observations allowed the team to determine the approximate location of the signal’s source: a distant galaxy several billion light years away. And as far as they knew, the galaxy seemed pretty small for something that housed such a powerful signal. An analysis of the discovery was recently published in The letters from the astrophysical diary.

“Finding a neutron star collision like we did is a game-changer,” Simone Dichiara, lead author of the study and an astrophysicist at Penn State University, said in a statement. nasa statement. “It may be the key to solving not one, but two important questions in astrophysics.”

Squinting into space

One of these two questions concerns gamma-ray bursts that apparently do not emerge from the core of a galaxy (where star formation is most active) or, indeed, from any galaxy. The signal, called GRB 230906A, implies that these rogue gamma-ray bursts literally eclipse their hosts, so that ground-based observatories are unable to notice that the smaller, fainter galactic hosts aren’t even there.

Consequently, when studying gamma-ray bursts, an “accurate X-ray position is crucial for identifying a candidate gamma-ray burst host galaxy that would otherwise be overlooked or misassigned,” the team notes in the paper. The researchers also considered the possibility that the galaxy was simply In fact So far, not necessarily small, but that was a “less likely explanation,” they said in the statement.

The team’s research also identified a stream of gas, approximately six times longer than the entire width of the Milky Way, flowing out of the host galaxy. This “tidal tail” likely formed through gravitational tug-of-war between galaxies over hundreds of millions of years.

“The gamma-ray burst lies directly within one of these tidal streams, suggesting that it took place within a small dwarf galaxy formed from material torn from its host during a galaxy collision,” Dichiara and study co-author Eleonora Troja, an astrophysicist at the University of Rome in Italy, wrote in a column about the findings in The conversation.

Creation of destruction

The second question concerns how heavy elements appear in stars located far from the centers of galaxies. Heavier elements like iron emerge from fusion chain reactions within the most massive stars. When these large stars explode in a supernova and leave behind a core with a mass approximately three times less than the Sun, a neutron star is born.

According to the US, these extremely dense stars are considered one of the universe’s key sources of even heavier elements such as gold and uranium. Department of Energy. Events like GRB230906A (an explosion of these densely packed elements) could essentially disperse the heavy elements to the outskirts of a galaxy, where a future star could grab the elements, the researchers explained.

“We had a rare insight into how destruction can be a catalyst for creation,” Jane Charlton, lead author of the study and an astrophysicist at Penn State, said in a statement. university statement. “The heavy elements in our body, like iron, for example, come from about 10,000 stars that were in our galaxy and died. It took billions of years, but that iron persisted on Earth, and as our bodies formed and evolved, they used that material.”

And the parallels could easily continue into the distant future of our galaxy, he added.

“Our own galaxy, the Milky Way, has a neighbor, the Andromeda galaxy, and within four or five billion years it will merge with the Milky Way,” he reflected. “This very thing could be happening, and tidal tails will form, lifting up heavy elements and enriching the universe.”