Hubble + Euclid stacking reveals ultra-faint glow; DM fraction ~99.94–99.98%

29:24>> Okay. >> And they used the Uklid image of the same spot with the Hubble image from the Spain same spot. stack them together >> and now you could reveal a same the same ultra faint diffused glow in between those four globular clusters. Those four globular clusters that were there, there was actually a little bit of light >> coming from the middle. So there are a few stars, not that many, >> but there's a chance. >> Uhhuh. Okay. And this is by cross referencing data sources, >> you can get a little more uh >> uh fidelity. >> Exactly. >> Okay. Yeah. And so with that diffuse glow now you can start fitting models and you can say okay what is the amount

30:07of stellar mass >> that's in that diffuse glow right in the middle right the amount of light that I'm getting is very little but from that I can make an estimate given how far I know it is like how far away it is um the Perseus cluster we can be like okay that's about 10 the six >> um suns so it's about 2 million suns okay it's not a lot But from what we know about the number of globular clusters and how luminous they are, we can also back calculate the amount of dark matter that should be there. >> And the dark matter is something like 10^ the 10. >> Mhm. >> So 10 billion suns.

30:49>> So we've got 10 billion suns worth of dark matter and only 2 million suns worth of normal matter. Meaning that the halo mass fraction, the amount of dark matter versus normal matter is 99.94 to 99.98%. >> This is where we get the 99 number. Like that's >> the size of the dark matter halo is about that of the large melanic cloud, which is one of the it's the biggest satellite galaxy to the Milky Way. You can only see it in the southern hemisphere, but the number of stars there is like a thousand times less than what we see in the large Magelenic cloud. M >> okay. So this is this is like a really really tiny tiny fraction of what should

31:30be there. There's not that many stars. There's like one in a thousand stars of what it should be. >> Right. And that's >> and that's and that's in that goes in direct that experimental data >> goes into direct conflict with the Lambda CDM. >> No, no, no. It doesn't it doesn't necessarily go into direct conflict because the lambda CDM does suggest that there should be a lot of dark matter galaxies. It's just now we found one. >> I see. >> Right. And now this this is where we get into how how could this be possible. Right. Okay. >> Now the first hypothesis is something called the failed giant hypothesis which is something like Cloud9 which we

32:11covered in a very recent episode. Yes. The idea is you've got some massive halo that's destined to be a galaxy