IceCube produced a diffuse neutrino map of the Milky Way, which the hosts compare to radio, optical, and gamma ray maps of the galaxy. The neutrino map is blobby but shows a bright central region matching the galactic nucleus, where Sagittarius A* and star forming regions sit, lining up with brightness seen in other wavelengths. The hosts also note that IceCube's data has failed to find expected neutrino counterparts to gamma ray bursts, which rules out gamma ray bursts as the dominant source of the high energy neutrinos detected so far.
- 01
The hosts compare the neutrino map's current blobby resolution to the early cosmic microwave background maps, expecting similar improvement in resolution over time.
- 02
They note the technical asymmetry behind the maps: gamma ray, optical, and radio data can be gathered with cameras on the ground or in space, while neutrino detection requires a full cubic kilometer detector like IceCube.
- 03
They describe the Nobel committee's illustration of the discovery, showing a charged particle and gamma ray being deflected or absorbed while a neutrino travels straight to the detector.
699 words · auto-generated from the episode video
54:16IceCube also mapped out the Milky Way with diffuse high energy neutrinos. And this, I think, is absolutely incredible. So here we're seeing maps of our own Milky Way in different bands. The first is radio, optical. This is what we see with our naked eye if you go to Joshua Tree or even better if you go to the middle of nowhere, and gamma rays. And neutrinos are on the bottom. Very blobby, but you don't understand just how hard it is to catch neutrinos and create a picture at that, right? Using a cubic kilometer worth of ice.
54:58We've created a map of the Milky Way and it kind of matches, right? The central blob in the center is the galactic nucleus where the supermassive black hole, Sagittarius, A star is, along with a bunch of other star forming regions, all sorts of random nonsense that's happening. And that is the region that is brighter in the neutrino band as well. This is a map of our Milky Way using neutrinos. I think that's absolutely incredible. It makes me think of the history of other sort of astronomical imaging and the progress. When you start, like it goes from blobby to resolve. Like I think like the cosmic microwave background kind of went from blobby to more resolved, but it kept its same structure.
55:38But as we got better over time, the resolution just became more well-defined and we kind of see it. Maybe we will get to a level that looks similar with neutrinos, but you gotta start somewhere. And because of the difficulty level as compared to the other three types, we can put stuff in space for the gamma rays. We can put the CCD on camera, on the ground and in space. No problem. But we need a massive thing for the neutrinos. We need a whole IceCube that is one kilometer by one kilometer by one kilometer. Big IceCube. Yeah, it's insane. One of the most important things that IceCube has done is actually falsify certain theories.
56:20Science is all about falsification, right? A theory is testable and if we can falsify it, we are making progress. One of the proposed sources, one of the things that people thought could be these extragalactic sources of really high energy particles was gamma ray bursts. We don't really know what gamma ray bursts are, but there's a burst of gamma rays from singular sources. We have found no significant association in the samples that we've discussed. And so those absences constrain the models because the people who were talking smack about, oh, it's obviously gamma rays. What's the big deal? Well, where are they? We see gamma rays from gamma ray bursts, but not that many neutrinos of this really high energy.
57:06There's no, like, because we would be able to do coincident detection with this as well. Exactly yeah. Not there. It's not there. I don't know what to tell you. I don't know what to tell you, right? So the achievement is recognized by this price. Yeah. This price is recognizing that exact achievement. And this is the Nobel committee drawing. Which we can now understand very well. Which we can now understand very well. It's showing a proton, which is in red, or a charged particle. It's sad because it's moving around because of extra galactic magnetic fields and magnetic fields in the Milky Way. There's a gamma ray that's also coming from these particle accelerations that are happening outside of our galaxy.
57:46But those things start interacting with the matter and they get stopped. The neutrino on the other hand, it's like, they use the V as kind of an angry eyebrow. You see that? And this thing is just coming at us. Yeah, it's coming straight at us into the IceCube detector and it's gonna create the detection that we want. This is so funny. And then it's got the little sensors inside the ice with the circles, right? Like the similar, like, shape for it. This is actually quite-- This one's pretty good. Yeah, this is quite nice. Yeah, this one's pretty good. I quite like that one.