The most distant known galaxy’s energy explosion could have been a satellite orbiting Earth

The cosmos is the scene of a variety of giant explosions. These include stellar flares, where the stars suddenly release magnetic energy; and neutron star mergers, where two dense stars collide. But one class of explosions outperforms the others: gamma-ray bursts are the most energetic explosions observed in the universe.

Gamma rays are one of the most energetic forms of light, and gamma ray bursts release almost unimaginable amounts. First discovered during the Cold War – by military satellites looking for signs of nuclear testing in the upper atmosphere – gamma-ray bursts are now believed to be caused by massive stars experiencing huge explosions when they run out of fuel. These events are rare, but so energetic that they can be observed in galaxies billions of light years away.

Recently, astronomers believed they had seen evidence of one of these explosions originating in the most distant galaxy on record. But a recently published article casts doubt on those claims, suggesting it may have been caused by a more mundane source much closer to home.

Gamma bursts

No gamma-ray bursts have yet been documented in our galaxy, which may not be a bad thing. A burst of gamma rays pointed directly at Earth would likely lead to a mass extinction event and the end of civilization as we know it. Undocumented events may in fact have already caused mass extinction events in Earth’s history.

However, gamma-ray bursts have been observed from afar. The article suggesting that the researchers had discovered a new gamma-ray burst in the most distant known galaxy was published in 2020. Using the Keck telescope on Mauna Kea, Hawaii, the researchers observed bands of the sky and saw a flash of light, just a few seconds, in one of their exhibits.

By modeling the duration and brightness of the flash, they ruled out the possibility that it was a natural or man-made satellite near them. They also ruled out a number of other astronomical explanations and concluded that the most likely explanation was, indeed, a gamma ray burst.

What was so unique about this discovery was that the team determined the direction of the event and discovered that it came from the same region as a galaxy known as GN-z11, which happens to be the most distant and oldest galaxy that we have yet discovered.

Was it an incredible cosmic coincidence? Or was it a sign that gamma-ray bursts were more common early in the universe, just 400 million years after the big bang? This latter finding would have great implications for our understanding of the formation of stars and galaxies in the early universe, and has generated much enthusiasm among astronomers.

But unease over the group’s findings surfaced, with some arguing that the flash was much more likely to come from an object in our solar system, which could be a natural (like a moon) or man-made satellite. In another article, a different team suggested that the most likely explanation was a reflection of a man-made satellite. The original authors followed through on these claims, doubling down on their interpretation of gamma-ray bursts, but the chorus of skeptics only grew louder.

Space debris

Now the controversy has taken another turn, with a new article recently published in Nature. The authors of this article suggest that the alleged gamma-ray burst was actually a lightning strike caused by a man-made satellite after all. The researchers used a public space tracking website to check for possible human satellite interference in the direction and when the flash was detected.

Around the time the original team was studying the sky, a Russian proton rocket reached low Earth orbit and freed its upper stages (dubbed Breeze-M), which then became space debris, orbiting around of the earth. By looking at the orbit of the space debris and matching the observations taken in the original study, the new team found that the flash could be simply explained by the top tier falling beyond the part of the sky that the telescope observed.

The proton rocket has been in service since the 1960s, and it’s not the only time one of its Breeze-M upper stages has made the news. In 2013, an explosion dispersed huge amounts of debris into orbit near Earth and left NASA scrambling to assess whether it would pose a danger to the International Space Station.

While this particular incident may have been particularly unlucky, with increasing amounts of garbage in space and the launch of large constellations of satellites by private company SpaceX and others in the years to come, it highlights the increasing difficulties that astronomers face in observing from the Earth’s surface.

Better databases on satellites and space debris will prevent these kinds of misidentifications. But growing light pollution from satellite constellations threatens the ability of ground-based telescopes to see even clearly enough to do cutting-edge science.

This article is republished from The Conversation under a Creative Commons license. Read the original article.