Just over three years ago, physicists working in Antarctica announced they’d detected the first evidence of mysterious subatomic particles, known as neutrinos, coming from outside our galaxy.
It was a huge moment for astrophysics, but since then, no one’s quite been able to figure out where those particles are coming from, and what’s sending them hurtling our way.
Until now, that is – a team of astronomers has just identified the possible source of one these extragalactic visitors, and it appears that it started its journey to us nearly 10 billion years ago, when a massive explosion erupted in a galaxy far, far away.
Let’s step back for a second here though and explain why this is a big deal. Neutrinos are arguably the weirdest of the fundamental subatomic particles.
They don’t have any mass, they’re incredibly fast, and they’re pretty much invisible, because they hardly ever interact with matter.
Like tiny ghosts, billions of neutrinos per second are constantly flowing through us, and we never even know about it.
In order to detect them, researchers have step up extravagant labs, like the IceCube Neutrino Observatory at the South Pole, where they wait patiently to capture glimpses of neutrinos streaking through the planet, and measure how energetic they are, to try to work out where they came from.
Usually that source is radioactive decay here on Earth or inside the Sun, or maybe from the black hole at the centre of our galaxy.
But in 2013, the IceCube researchers announced they’d detected a couple of neutrinos so unimaginably energetic, they knew they must have come from outside our galaxy.
These neutrinos were named ‘Bert’ and ‘Ernie‘ (seriously) and they were the first evidence of extragalactic neutrinos.
Their discovery was followed by the detection of a couple of dozen more, slightly less energetic, extragalactic neutrinos over the coming months.
Then at the end of 2012, they spotted ‘Big Bird‘.
At the time it was the most energetic neutrino ever detected, with energy exceeding 2 quadrillion electron volts – that’s more than a million million times greater than the energy of a dental X-ray.
Not bad for a massless ghost particle.
Since then, teams across the world have been working to figure out where the hell this anomaly had come from. And now we might finally have a suspect.
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