NASA telescope discovers mysterious hotspot of high-energy particles beyond our galaxy

• Astronomers investigating the wallpaper of our universe stumbled upon a mysterious signal.
• Something unknown seems to be spewing high-energy cosmic rays and gamma rays.
• This pattern in the sky could help solve one of astrophysics' biggest mysteries.

NEW ORLEANS — Astronomers using a NASA space telescope have discovered a region of the sky with a mysterious concentration of some of the universe's highest-energy radiation.

The astronomers were mapping space's background glow of gamma rays, the brightest and most energetic type of light on the electromagnetic spectrum. They were surprised to find way more gamma rays coming from one part of the sky than anywhere else.

Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA, called the discovery a "total conundrum" when he presented it at a meeting of the American Astronomical Society in New Orleans last Thursday.

The purple rings in the image below show where they think this signal is coming from. They have 95% confidence that it's somewhere within the outer purple ring. More likely than not, it's somewhere inside the inner purple ring, too. The orange strip across the center of the image is the plane of the Milky Way.

This feature might be connected to a hot spot of ultra-high-energy cosmic rays (UHECRs) coming from a similar direction and with almost exactly the same magnitude. These are the rarest and most energetic of the charged subatomic particles called cosmic rays.

Unlike gamma rays — which are frequently detected shooting out of black holes and dying or dead stars — the origin of UHECRs is "one of the biggest mysteries in astrophysics," NASA explained in a statement.

Because this unexpected gamma-ray feature seems to match a similar feature in UHECRs, it could be a clue in that mystery.

This discovery deals with some of the most intense radiation in the universe. These gamma rays carry about 1 billion times the energy of visible light. And UHECRs have 1 billion times more energy than gamma rays.

Kashlinsky and his colleagues don't know what's causing this super-energetic signal in the universe.

But he says it's probably coming from some yet-undiscovered phenomenon within 300 million light-years from us.

"It's a huge area of the sky where exactly what is happening is hard to know," Kashlinsky said.

Looking at the wallpaper of the universe

Kashlinsky and his colleagues stumbled upon this new mystery when they were analyzing 13 years of data from NASA's Fermi Gamma-ray Space Telescope.

They were looking for additional signs of a pattern in the cosmic microwave background — the lingering radiation from the first light that traveled freely through the universe after the Big Bang. The CMB is like wallpaper behind all the galaxies in the universe.

There's one odd thing about it, though. The CMB is hotter (more microwaves) toward the constellation Leo and colder (fewer microwaves) in the other direction.

Astronomers think this is simply because of our solar system's movement against the background, which is about 230 miles per second.

It's like an ambulance passing by, where the siren has one pitch as it approaches you, and sounds like another pitch as it recedes in the distance. This pattern in the CMB is called a dipole.

Kashlinsky wanted to test that theory about our solar system's movement by checking to see if there's a similar dipole pattern in other forms of light.

If other light forms have different patterns than the CMB, that would mean it's not just our solar system's movement creating the inconsistency. Something else is going on — possibly a yet-undiscovered event in the very first micro-moments of the universe's birth.

Such a discovery "could provide us with a glimpse into physical processes operating in the very early universe, potentially back to when it was less than a trillionth of a second old," coauthor Fernando Atrio-Barandela, a professor of theoretical physics at the University of Salamanca in Spain, said in the NASA press release.

An unexpected clue in one of the cosmos' biggest mysteries

So Kashlinsky's group assessed the gamma-ray background — a diffuse glow of gamma rays that black holes and supernovae create across the cosmos.

They found a distinct pattern, but it was 10 times stronger than it should be from the motion of our solar system.

What's more, the dipole pattern didn't match the one in the CMB. Instead, it matched the pattern of UHECRs.

The 2017 discovery that UHECRs had their own dipole pattern deepened the mystery around them. Now, the discovery that gamma rays have a similar dipole offers a new clue.

A paper describing the discovery was published in The Astrophysical Journal Letters on January 10.

Kashlinsky and his team think the gamma-ray and UHECR patterns might be related, but they're not sure how or why. Some unknown object or process out there in the universe may be producing both the gamma rays and the UHECRs.

To solve the mystery, "more work and better, more refined measurements of both are needed," Kashlinsky told Business Insider in an email.

To that end, his team plans to analyze more Fermi telescope data in the future.