What if an entire galactic nucleus was blasting high energy radiation directly at Earth?
Credit: NASA
A new paper in the Journal of Cosmology and Astroparticle Physics has put forth an intriguing theory: A so-far unexplainable neutrino could have been blasted at Earth by a cosmic particle accelerator known as a “blazer.”
But let’s back up.
For a while now, we’ve been reporting on a watershed 2023 neutrino detection that left physicists scratching their heads. Seen on a neutrino detector housed at the bottom of the Mediterranean Sea, this particle, so elusive it’s often called a “ghost particle,” carried far more energy than had ever been predicted for its type.
The detection immediately required an explanation and generated considerable speculation. Now, a few years on from the original detection, we’re finally seeing this conversation turn into some peer-reviewed papers on the subject.
A few months ago, we saw a study detailing one of the most widely supported ideas: that the neutrino originated from an exploding black hole. This is an attractive concept, largely because exploding black holes are intrinsically interesting.
As mentioned, we’ve explored that idea before, but suffice it to say it involves the explosive end of primordial singularities that have existed since the beginning of time. So, check that off.
Credit: NASA
This new paper shifts the focus to a so-called “blazar” as the potential explanation.
A blazar is a type of active galactic nucleus (AGN), which is itself a super-cluster of stars that shows significant luminosity across the electromagnetic spectrum, much of which can’t be attributed to emissions from stars. The non-stellar radiation is largely believed to arise from the accretion of matter by a supermassive black hole at the center.
That is to say, as the black hole pulls matter in and over its own event horizon, some portion of the energy contained within that matter is blasted out. Because this swirling matter forms a disk, the path of least resistance for emissions is along the poles, causing radiation to be beamed out in the two directions perpendicular to the disk.
One of these jets can outshine the entire Milky Way by many thousands of times, but it’s highly directional, meaning the power detected will depend on the beam’s angle relative to the observer.
This illustration shows a blazar’s orientation, relative to Earth.
Credit: NASA
This type of object is generally called a quasar. When the particle jet is oriented towards Earth, letting us see the full luminosity, it’s called a blazar. A blazar directs the full power of a quasar at Earth, allowing us to see all its characteristics.
One feature of the 2023 detection wasn’t just the neutrino’s power, which was tens of thousands of times more energetic than can be achieved by the Large Hadron Collider, but the fact that it came without much electromagnetic radiation, like x-rays or gamma rays.
The researchers posited a collection of blazars that would influence each others’ emissions; they found that such a field cluster of interacting blazars could create the neutrino energies observed and the peculiar mix of energies, too.
The only problem is that 2023 neutrino detection is the only one of its kind (so far), which would seem to indicate that whatever created that particle must be a relatively rare event. A blazar, however, would presumably keep emitting particles over time.
This detection of a single particle was so far outside expectations that scientists will likely spend years more looking for explanations. More daunting is their overarching task: To figure out exactly how nature created a particle that humanity could only produce using a particle collider with a circumference equal to that of planet Earth.
