98
The first ever neutrino image of the Milky Way galaxy captured by the IceCube Neutrino Observatory
(media.kbin.social)
this post was submitted on 29 Jun 2023
98 points (100.0% liked)
Space
101 readers
1 users here now
Cover author: Michał Kałużny http://astrofotografia.pl/
founded 2 years ago
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
What is actually used to capture neutrino images? Isn't their whole thing that they basically don't interact with matter almost at all?
Neutrinos can interact with matter via the weak force, which is so weak and short ranged that most neutrinos incident on matter just pass through it. However, you can imagine if a HUGE chunk of neutrinos falls on matter, at least a few are bound to interact, statistically speaking. These interactions are like collisions, and the collision may result in generation of new particles. If these new particles are energetic enough, they emit a special type of radiation, which can be detected through sensors. So, you're not directly capturing neutrinos, but are making the inference that they are there, because you know a weak force interaction has taken place if your sensor goes off. And to make sure something like cosmic radiation doesn't affect detection, this particular detector is isolated under a huge sheet of ice in Antarctica.
I recall reading something - maybe it was from xkcd? - about how close to a supernova you'd have to be for the neutrino radiation alone to deliver a lethal dose. I think the conclusion was about 1au away, probably well inside the radius of the star that was exploding.
Since i believe supernovae are one of the few significant sources of neutrinos, to have to be so close to the source that you would have long since died of other causes before you could absorb significant energy from neutrinos speaks to how little they actually interact with matter.
My favorite fact from that article (indeed xkcd) isn't about neutrinos though, but this:
The answer is the supernova, by 9 orders of magnitude. So the supernova at the Sun's distance is about a billion times brighter than a hydrogen bomb pressed against your eyeball.
https://what-if.xkcd.com/73/
Oh i had forgotten that! Thanks for reminding me!
So would that actually make a difference to the speed at which you're incinerated?
The neutrinos? According to the article you'd probably be inside the star to be at the neutrino-lethal distance, so you'll clearly be dead before it even goes supernova. :-)
If it were still lethal at a distance you could survive, my slightly informed guess is that it could matter, as AFAIK supernovas tend to release the neutrinos before most of the light.
However I have no idea for how long the main part of the neutrino flood last or how long it'll take to kill you, could be anything from less than a second to minutes or hours, at which time you'd certainly be dead from the rest of the supernova.