6 ms·

Yes, this is different from dark matter. This is baryonic "matter" that is predicted by our theories but that had not been previously detected. However the tit

by nfc 6y ago

Yes, this is different from dark matter. This is baryonic "matter" that is predicted by our theories but that had not been previously detected. However the title is misleading, this is not the discovery of this matter even if the press release makes it look so. Previous detections of this matter had been discussed on HN before https://news.ycombinator.com/item?id=17953600 https://news.ycombinator.com/item?id=17953600 What this is is an advance on our understanding of this previously undetected matter. You can read more about it here https://www.aanda.org/articles/aa/full_html/2020/11/aa38521-20/aa38521-20.html https://www.aanda.org/articles/aa/full_html/2020/11/aa38521-..., this work has advanced our knowledge of the temperature and density of the cosmic filaments where this previously undetected matter is. I'm not an astrophysicist but I did my PhD about the stacking technique used in this paper (but applied to other problem). It was a long time ago though, I could be forgetting something important.

mudita 6y ago
Could you say more about what this stacking technique is? I got the impression that it's about combining different images by aligning and averaging them to get a better signal-to-noise-ratio, is this correct?
- AnHonestComment 6y ago
  My understanding is like this: Imagine that you get one pixel for each hole in a chain link fence — the average color of light coming through that hole. If you take a second fence, that’s out of alignment with the first — you get better resolution because each hole in the original fence overlaps with several in the second fence, and you can examine their overlaps. The “size” of pixel of the two fences together is smaller than the size of the fence grating. A bunch of different overlaps, and some fancy statistics, lets you actually do that with space pictures. In essence, you reduce from the normal pixel size to the area of overlap between pixels. But if you only have the snapshot averages, you have to guess at what the original was — so statistical result.
  - Cancan82 6y ago
    This was a really great explanation. I love smart people who can dumb it down for me. Thank you. Very cool.
SiempreViernes 6y ago
Open access <3
Cancan82 6y ago
Thank you - this is really and the background here is helpful. Appreciate it very much.

by nfc 6y ago

mudita 6y ago

Could you say more about what this stacking technique is? I got the impression that it's about combining different images by aligning and averaging them to get a better signal-to-noise-ratio, is this correct?

AnHonestComment 6y ago
My understanding is like this: Imagine that you get one pixel for each hole in a chain link fence — the average color of light coming through that hole. If you take a second fence, that’s out of alignment with the first — you get better resolution because each hole in the original fence overlaps with several in the second fence, and you can examine their overlaps. The “size” of pixel of the two fences together is smaller than the size of the fence grating. A bunch of different overlaps, and some fancy statistics, lets you actually do that with space pictures. In essence, you reduce from the normal pixel size to the area of overlap between pixels. But if you only have the snapshot averages, you have to guess at what the original was — so statistical result.
- Cancan82 6y ago
  This was a really great explanation. I love smart people who can dumb it down for me. Thank you. Very cool.

SiempreViernes 6y ago

Open access <3

Cancan82 6y ago

Thank you - this is really and the background here is helpful. Appreciate it very much.