4 ms·

Physicists produce neutrino images of Milky Way galaxy

120 points by _Microft 3y ago

_Microft 3y ago
The paper is here, for those who directly want to go there instead: https://www.science.org/doi/10.1126/science.adc9818 https://www.science.org/doi/10.1126/science.adc9818
sbierwagen 3y ago
If you want to see the actual diagram, rather than the composite overlaying it with a visible light image of the milky way, here is figure 4 from the paper: https://res.cloudinary.com/icecube/images/q_auto/v1671570509/adc9818_Figure_fig4_seq4_v1-1/adc9818_Figure_fig4_seq4_v1-1.jpg?_i=AA https://res.cloudinary.com/icecube/images/q_auto/v1671570509... (From the media gallery here: https://icecube.wisc.edu/gallery/high-energy-neutrinos-from-the-galactic-plane/ https://icecube.wisc.edu/gallery/high-energy-neutrinos-from-... ) As you'd expect, the resolution from a 86x60 neutrino detector array is not great.
- causality0 3y ago
  Right. That doesn't seem to line up super well with the galactic disc. Even those diagrams look like they've had an awful lot of smoothing.
  - _Microft 3y ago
    > "In the Milky Way Galaxy, cosmic rays (high-energy protons and heavier nuclei) interact with galactic gas and dust to produce both gamma rays and neutrinos.", from the article The detected neutrinos were not necessarily produced in the vicinity of the source of the cosmic rays as I understand it. Imagine it like a bank of fog lighting up in the night because a car with headlights is moving towards it.
    - piannucci 3y ago
      Yes; however, because of the extreme kinetic energy and momentum of the cosmic ray inputs to these collision events, the output neutrinos will be emitted in a tightly focused cone parallel to the path of the original ray. You can be fairly confident that the original source is close to the line-of-sight.
wthomp 3y ago
As has been pointed out elsewhere, this is the first image of our galaxy in something other than light (radio, infrared, x rays, gamma rays are all photons).
- __MatrixMan__ 3y ago
  Odd timing, given that only a few days ago we were talking about a gravitational wave background (https://astrobites.org/2023/06/28/drop-the-bass-evidence-for-a-gravitational-wave-background-from-a-galaxy-sized-detector/ https://astrobites.org/2023/06/28/drop-the-bass-evidence-for...) not that we're in a position to render that as an image, but it's close.
  - deepsun 3y ago
    Japan is also going to launch muon observatory.
nonameiguess 3y ago
Unfortunately, the actual paper seems to be paywalled, but stories like this often seem to do a poor job of motivating why research like this is interesting. For both this and all of the articles coming out about gravitational wave detection, these technologies allow us to sense things that can't be seen with light. Gravitational waves are produced by binary black hole systems and mergers, which don't give off any detectable radiation, and neutrinos can be produced by spin down of neutron stars we don't have any other easy way of detecting. But, these also potentially give us a window into the deep past. The cosmic microwave background represents the furthest back in time we can ever see with light, and it happened during the first formation of neutral hydrogen atoms when the universe first cooled enough to allow that, and thus light could travel without being immediately scattered by free electrons, which was 378,000 years after the Big Bang. Seeing anything before that is impossible. Neutrinos, however, first decoupled from matter 1 second after the Big Bang. The possibility of being able to detect a cosmic neutrino background from this event would allow us to detect the early universe much earlier than we can with light. And if gravity decoupling from the strong and electroweak forces is ever detectable in a cosmic gravitational wave background, that would have happened even earlier, and represents the earliest possible viewing of the universe by any means whatsoever. I'm not a cosmologist and have no idea what usable data would ever come from being able to see these things, but keep in mind at least one reason we've had so much difficulty developing a grand unified theory and theory of everything even after conquering electroweak, is the inability to produce the enormous energies required to recouple the forces in a lab. A particle accelerator that could do it for strong force recoupling to electroweak would have to be the size of Pluto's orbit. But there is at least one event in nature where the necessary energy existed, which is the early universe. We've just never been able to see it.
- chevman 3y ago
  Is there anything in the math or observations at this point to indicate the big bang is the other side of a black hole singularity?
  - dotnet00 3y ago
    PBS Spacetime covered this topic: https://youtu.be/jeRgFqbBM5E https://youtu.be/jeRgFqbBM5E Basically, with our current understanding, the only thing that makes the big bang and black holes seem connected is that they're both singularities. But, there's no explanatory value associated with the idea of the universe being the inside of a black hole, and thus there's no way to attempt to test it.
NoMoreNicksLeft 3y ago
I don't think I understand any of this. You have to bury a few zillion tons of water in a pitch-black salt mine a mile underneath the surface, and run detectors that see a dim flash of light when one of these hits a water molecule, right? How is that in any way directional? Or is there a way to compile an image from this without directionality?
- _Microft 3y ago
  The "dim flash of light" is called Cherenkov radiation and there's directional information encoded in it. Depending on which (or when a?) particular detector saw that light, the direction of the incoming particle can be calculated. https://en.wikipedia.org/wiki/Cherenkov_radiation https://en.wikipedia.org/wiki/Cherenkov_radiation
- Taniwha 3y ago
  Icecube is at the south pole - the zillions of ton s of water is just ice
  - etrautmann 3y ago
    Is that true? They don’t fill a chamber with heavy water?
    - MikeDelta 3y ago
      Water and ice versions exist, IceCube consists of detectors dug into ice and Super Kamiokande (example) is a big container of ultrapure water (not heavy). Hyper Kamiokande will be even bigger. https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory https://en.wikipedia.org/wiki/Super-Kamiokande https://en.wikipedia.org/wiki/Super-Kamiokande https://en.wikipedia.org/wiki/Hyper-Kamiokande https://en.wikipedia.org/wiki/Hyper-Kamiokande
      - 0PingWithJesus 3y ago
        Most neutrino experiments don't/didn't use heavy water, but the SNO experiment did. https://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory https://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory
oblib 3y ago
This link is to the image shown in the article but it's a lot larger and it's an animated gif. https://drexel.edu/news/~/media/Drexel/Core-Site-Group/News/Images/v2/story-images/2023/June/Neutrino-Animated-Gif_1920x1080_wide_IG_Fin.ashx https://drexel.edu/news/~/media/Drexel/Core-Site-Group/News/...
RoyGBivCap 3y ago
>“What’s intriguing is that, unlike the case for light of any wavelength, in neutrinos, the universe outshines the nearby sources in our own galaxy,” says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator of IceCube. Wild stuff.
oh_sigh 3y ago
Wouldn't neutrinos be the optimal way for one civilization to communicate with another over a vast distance?
- saagarjha 3y ago
  Hard to build a receiver for.
deleted 3y ago
[deleted]

120 points by _Microft 3y ago

The paper is here, for those who directly want to go there instead: https://www.science.org/doi/10.1126/science.adc9818 https://www.science.org/doi/10.1126/science.adc9818

sbierwagen 3y ago

If you want to see the actual diagram, rather than the composite overlaying it with a visible light image of the milky way, here is figure 4 from the paper: https://res.cloudinary.com/icecube/images/q_auto/v1671570509/adc9818_Figure_fig4_seq4_v1-1/adc9818_Figure_fig4_seq4_v1-1.jpg?_i=AA https://res.cloudinary.com/icecube/images/q_auto/v1671570509... (From the media gallery here: https://icecube.wisc.edu/gallery/high-energy-neutrinos-from-the-galactic-plane/ https://icecube.wisc.edu/gallery/high-energy-neutrinos-from-... ) As you'd expect, the resolution from a 86x60 neutrino detector array is not great.

causality0 3y ago
Right. That doesn't seem to line up super well with the galactic disc. Even those diagrams look like they've had an awful lot of smoothing.
- _Microft 3y ago
  > "In the Milky Way Galaxy, cosmic rays (high-energy protons and heavier nuclei) interact with galactic gas and dust to produce both gamma rays and neutrinos.", from the article The detected neutrinos were not necessarily produced in the vicinity of the source of the cosmic rays as I understand it. Imagine it like a bank of fog lighting up in the night because a car with headlights is moving towards it.
  - piannucci 3y ago
    Yes; however, because of the extreme kinetic energy and momentum of the cosmic ray inputs to these collision events, the output neutrinos will be emitted in a tightly focused cone parallel to the path of the original ray. You can be fairly confident that the original source is close to the line-of-sight.

wthomp 3y ago

As has been pointed out elsewhere, this is the first image of our galaxy in something other than light (radio, infrared, x rays, gamma rays are all photons).

__MatrixMan__ 3y ago
Odd timing, given that only a few days ago we were talking about a gravitational wave background (https://astrobites.org/2023/06/28/drop-the-bass-evidence-for-a-gravitational-wave-background-from-a-galaxy-sized-detector/ https://astrobites.org/2023/06/28/drop-the-bass-evidence-for...) not that we're in a position to render that as an image, but it's close.
- deepsun 3y ago
  Japan is also going to launch muon observatory.

nonameiguess 3y ago

Unfortunately, the actual paper seems to be paywalled, but stories like this often seem to do a poor job of motivating why research like this is interesting. For both this and all of the articles coming out about gravitational wave detection, these technologies allow us to sense things that can't be seen with light. Gravitational waves are produced by binary black hole systems and mergers, which don't give off any detectable radiation, and neutrinos can be produced by spin down of neutron stars we don't have any other easy way of detecting. But, these also potentially give us a window into the deep past. The cosmic microwave background represents the furthest back in time we can ever see with light, and it happened during the first formation of neutral hydrogen atoms when the universe first cooled enough to allow that, and thus light could travel without being immediately scattered by free electrons, which was 378,000 years after the Big Bang. Seeing anything before that is impossible. Neutrinos, however, first decoupled from matter 1 second after the Big Bang. The possibility of being able to detect a cosmic neutrino background from this event would allow us to detect the early universe much earlier than we can with light. And if gravity decoupling from the strong and electroweak forces is ever detectable in a cosmic gravitational wave background, that would have happened even earlier, and represents the earliest possible viewing of the universe by any means whatsoever. I'm not a cosmologist and have no idea what usable data would ever come from being able to see these things, but keep in mind at least one reason we've had so much difficulty developing a grand unified theory and theory of everything even after conquering electroweak, is the inability to produce the enormous energies required to recouple the forces in a lab. A particle accelerator that could do it for strong force recoupling to electroweak would have to be the size of Pluto's orbit. But there is at least one event in nature where the necessary energy existed, which is the early universe. We've just never been able to see it.

chevman 3y ago
Is there anything in the math or observations at this point to indicate the big bang is the other side of a black hole singularity?
- dotnet00 3y ago
  PBS Spacetime covered this topic: https://youtu.be/jeRgFqbBM5E https://youtu.be/jeRgFqbBM5E Basically, with our current understanding, the only thing that makes the big bang and black holes seem connected is that they're both singularities. But, there's no explanatory value associated with the idea of the universe being the inside of a black hole, and thus there's no way to attempt to test it.

NoMoreNicksLeft 3y ago

I don't think I understand any of this. You have to bury a few zillion tons of water in a pitch-black salt mine a mile underneath the surface, and run detectors that see a dim flash of light when one of these hits a water molecule, right? How is that in any way directional? Or is there a way to compile an image from this without directionality?

_Microft 3y ago
The "dim flash of light" is called Cherenkov radiation and there's directional information encoded in it. Depending on which (or when a?) particular detector saw that light, the direction of the incoming particle can be calculated. https://en.wikipedia.org/wiki/Cherenkov_radiation https://en.wikipedia.org/wiki/Cherenkov_radiation
Taniwha 3y ago
Icecube is at the south pole - the zillions of ton s of water is just ice
- etrautmann 3y ago
  Is that true? They don’t fill a chamber with heavy water?
  - MikeDelta 3y ago
    Water and ice versions exist, IceCube consists of detectors dug into ice and Super Kamiokande (example) is a big container of ultrapure water (not heavy). Hyper Kamiokande will be even bigger. https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory https://en.wikipedia.org/wiki/Super-Kamiokande https://en.wikipedia.org/wiki/Super-Kamiokande https://en.wikipedia.org/wiki/Hyper-Kamiokande https://en.wikipedia.org/wiki/Hyper-Kamiokande
    - 0PingWithJesus 3y ago
      Most neutrino experiments don't/didn't use heavy water, but the SNO experiment did. https://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory https://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory

oblib 3y ago

This link is to the image shown in the article but it's a lot larger and it's an animated gif. https://drexel.edu/news/~/media/Drexel/Core-Site-Group/News/Images/v2/story-images/2023/June/Neutrino-Animated-Gif_1920x1080_wide_IG_Fin.ashx https://drexel.edu/news/~/media/Drexel/Core-Site-Group/News/...

RoyGBivCap 3y ago

>“What’s intriguing is that, unlike the case for light of any wavelength, in neutrinos, the universe outshines the nearby sources in our own galaxy,” says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator of IceCube. Wild stuff.

oh_sigh 3y ago

Wouldn't neutrinos be the optimal way for one civilization to communicate with another over a vast distance?

saagarjha 3y ago
Hard to build a receiver for.

deleted 3y ago

[deleted]