About a year ago, a team of astronomers working in Hawaii spotted Something in the night sky. A four-minute flash of light.
Depending on who you ask, this flash was either a powerful explosion from 13.4 billion years ago – a virtual snapshot of the universe as it existed barely 400 million years after its formation – or a reflection of a piece of space debris looping around the Earth. Scientific treasure or rubbish.
Despite a year of heated debate and a flurry of study, we may never know what caused this mysterious lightning bolt, dubbed “GN-z11-flash” for the distant galaxy it may have come from. But this is high-stakes astronomy, whether it’s a landmark career-defining discovery or the kind of embarrassment people spend their entire lives trying to avoid.
As astronomers push the boundaries of technology and scholarship to peer deeper and deeper into space, they face more and more obstacles. Our telescopes are not good enough. Our computers are too slow. Our data is too thin. Distant sightings are so delicate and shrouded in uncertainty that a passing piece of space garbage can ruin everything.
In 2017, a team of astronomers led by Linhua Jiang, of the Chinese University of Peking, peered through the Keck I telescope in Hawaii, observing GN-z11. They were using an infrared spectrometer attached to the telescope, expecting to scan the galaxy – which 13.4 billion light years away is the oldest and most distant object humanity has ever observed – for clues. on the beginnings of the history of the universe. GN-z11, like many very old and very distant galaxies, is only visible in infrared.
They didn’t expect to see an explosion. But if you believe the team’s subsequent analysis, that’s exactly what happened. For 245 seconds, Keck I recorded what appeared to be a possible gamma-ray burst from the universe’s childhood.
To observe a 13.4 billion-year-old gamma-ray burst, or GRB, would be a profound fluke with equally profound implications for the study of, well, all. “GRBs and their associated broadcasts can be used to probe the history of star formation and reionization in the Age of Cosmic Dawn,” Jiang and his team wrote in their original article in the journal. scientist. Nature astronomy in December 2020.
“Reionization” refers to the eons half a billion years after the Big Bang, when the hydrogen making up most of the atoms in the universe ionized and cloudy space became transparent. It’s a mysterious era – the first eons of light after a period of hundreds of millions of years in which space swirled with opaque gases.
To witness an explosion from this period would be a scientific blow. “This means that gamma-ray bursts can be produced effectively at a very early stage,” Jiang told The Daily Beast. In other words, the explosions that we associate with star dying and the creation of black holes started very early. If gamma rays erupted as long as 13.4 billion years ago, it means that the universe – its structure and how galaxies are formed – have evolved. quick in what we see around us today.
But other astronomers weren’t convinced that Jiang and his team had seen anything of interest. The chances of spotting a gamma-ray burst 13.4 billion light-years away are infinitely slim, explained a team led by Michał Michałowski, an astronomer at Adam Mickiewicz University in Poland, in Nature astronomy in October.
In astronomy, a “redshift” is the change in the infrared signature of a distant galaxy that helps us determine its age. The GN-z11 naturally has a very high redshift, which suggests that it is old. But astronomers have not confirmed any other distant galaxy this ancient. The next oldest galaxy, EGSY8p7, has a redshift of 8.7, which means it is likely hundreds of millions of years younger than GN-z11.
Astronomers should find many more galaxies in the GN-z11 age range and spend a lot more time pointing telescopes at them in order to know what a gamma-ray burst looks like from these old galaxies, noted Michalkowski and his team. . “A larger sample of very high redshift galaxies is needed to detect such distant GRBs.”
It was well, far more likely that Jiang and his team caught a reflection of the abandoned Breeze-M upper stage from a 6-year-old Russian Proton rocket. “We searched Space-Track, the largest publicly available database of earth satellites and space debris for an object near the position of the GN-z11 flash at the time of the observations,” Michałowski’s team wrote. “We found the Breeze-M space junk.”
This particular argument is, in part, common sense, Michałowski told The Daily Beast. “The conclusion is that either it was an extraordinary discovery of something that we haven’t seen yet – a redshift 11 gamma ray burst – or an obvious explanation with well-identified space debris, of which we we are certain that it passed either through the field of view of the Keck telescope or just outside of it… with all the properties compatible with being a flash.
“Anyone can choose which explanation they prefer, but I have no doubts myself,” added Michałowski. He said he considered the controversy “settled”.
Jiang and his team disagree. “We looked at our records and found that this satellite was excluded in our initial analysis,” they explained in a new article, a preprint of which appeared online last week but has yet to be peer reviewed. .
Jiang et als calculations place the Russian rocket shell and the GN-z11’s flash potential a few inches in the telescope’s field of view – a distance they say should prevent confusion between the rocket and a burst of rays gamma of the distant galaxy. Moreover, they added, the reflection of the rocket “was much lower than what was needed to produce the flash.”
The year-long back-and-forth, which included two other major critiques of Jiang’s team’s findings, has so far ended in deadlock, with no resolution in sight. “We will never know the true nature of this flash,” Jiang said.
“Everyone can choose the explanation they prefer, but I have no doubts myself.“
– Michał Michałowski
If we had a lot of good data on confirmed gamma-ray bursts billions of light years away, maybe we could compare them to the GN-z11 flash and see if they match. Jiang said he looked and found nothing to compare. “I spent a lot of time looking,” he explained. “Unfortunately, we did not get such data. “
This could change in the future. Better telescopes, like NASA’s new James Webb Space Telescope, launched on December 25 as a Christmas present, combined with very powerful computers could help us spot and categorize distant explosions. Over time, luck, and new technology, we may eventually re-evaluate the GN-z11-flash.
But Bing Zhang, a University of Nevada astronomer and a member of Jiang’s team, urges patience. Many. “Very powerful telescopes are needed to continuously monitor many distant but weak galaxies in order to limit the rate of GN-z11 flash-like events,” he told The Daily Beast.
It is possible that a year ago, astronomers had a fleeting glimpse of the infancy of the universe. It’s also possible that they had a fleeting glimpse of Russian space junk. For the foreseeable future, we probably won’t know what it was.