Missing satellites problem (why we expect hundreds more halos)

13:42>> Okay. And that's really crazy. >> Okay. >> Yeah. >> So why do we even care, right? this intensive hunt for something like a candidate dark galaxy. It's motivated by two crises that are in the center of this cosmological model that we called lambda CDM. You know that thing I told you before about 5% normal matter, 25% dark matter, the rest being dark energy. I think it was this one. Yes. >> Yeah. Exactly. So this is the model that we have today. Yes. >> Now fine >> if if that is the model, right? There should be consequences of that model. There are certain consequences of the model that we do not see. >> The the point being we have an understanding of the universe. >> Yeah. And we're like this is our best

14:23guess. And then there's always people who are like but that doesn't really make sense for these two reasons. >> Got it. It doesn't it doesn't it it doesn't compute. >> Yeah. It doesn't compute. And these are the two things specifically that do not compute. The first one is the missing satellite problem. Okay. these dark matter simulations. When you use that original 5% normal matter, 25% dark matter, blah blah blah. You press play on a universe, you set it up in the computer, and you press play. Simulations predict that there should be about 500 orbiting dark matter sub halos around something that is the size of the Milky Way. >> Okay, >> the idea is for every big halo of dark

15:03matter condensing, right, dark matter is still gravitationally bound. So the universe is expanding. There's a bunch of dark matter. There's going to be tiny fluctuations where there's a little bit more matter here, a little less matter here. And so it's going to start clumping because gravity is going to take that over dense region is what we call it. And we're going to start clumping that way. Now around those big clumps, there's going to be smaller clumps. Around those smaller clumps, there's going to be even smaller clumps. There's like a power law structure. And >> what we expect is there should be a lot more small clumps, right, >> than what we see, >> right? That is the missing satellite problem. >> We we we see big a couple big clumps. >> Yeah. >> But the cascading the second and third order clumps we should be seeing are not

15:44present. >> Exactly. And that's what we're seeing over here. Um the the triangles with the error bars, that's observation. Yes. >> The lines are theory. And you can see that for >> larger >> increasing mass, we're fine. >> It So when the mass increases, the observation matches the theory. Yes, but for these smaller clumps, these satellite galaxies, there's a massive discrepancy orders of magnitude >> because because of the power law, we should be seeing significantly more smaller dark matter uh clusters or halos >> than the large ones. But the the rate of increase of the number from observation

16:24is very like the quite low. >> Yeah, there's like there's like a point where it's just like we just we just see way too few. Yes. Okay. So the question is, I mean, maybe maybe these smallest halos are present, but they're completely dark, which is why we don't see them. There's no stars. So like, what are you what are you going to see? >> It's a bunch of cloud nines from our from our star dark matter cloud. >> Exactly. And so Cloud9 was trying to solve the similar problem. And this is kind of solving that similar problem too. If this is truly there, right? >> Okay. >> Now, the second, and this is something that Cloud9 was not doing. So this is novel novel. It's called the cusp core