Chance to "see" dark matter

[Arch2008]

http://news.yahoo.com/s/space/20081106/sc_space/mysteriousdarkmattermightactuallyglow

 

This caught my eye.

[Martin]

Good find!

Simon White is a worldclass astrophysicist. The fact that he signed off on this almost guarantees it will prove important. There are other ways to see dark matter (e.g. by weak lensing) and clouds of dark matter have been mapped, but this could prove an essential part of the picture. For people who want more detail, here is the article that was published in Nature:

 

http://arxiv.org/abs/0809.0894

A blueprint for detecting supersymmetric dark matter in the Galactic halo

Authors: Volker Springel (1), Simon D.M. White (1), Carlos S. Frenk (2), Julio F. Navarro (3,4), Adrian Jenkins (2), Mark Vogelsberger (1), Jie Wang (1), Aaron Ludlow (3), Amina Helmi (5) ((1) MPA, (2) Durham, (3) UVic, (4) UMass, (5) Groningen)

to appear in Nature, 23 pages, 8 figures

(Submitted on 5 Sep 2008)

 

"Dark matter is the dominant form of matter in the universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species. In this case, annihilation of dark matter in the halo of the Milky Way should produce gamma-rays at a level which may soon be observable. Previous work has argued that the annihilation signal will be dominated by emission from very small clumps (perhaps smaller even than the Earth) which would be most easily detected where they cluster together in the dark matter halos of dwarf satellite galaxies. Here we show, using the largest ever simulation of the formation of a galactic halo, that such small-scale structure will, in fact, have a negligible impact on dark matter detectability. Rather, the dominant and likely most easily detectable signal will be produced by diffuse dark matter in the main halo of the Milky Way. If the main halo is strongly detected, then small dark matter clumps should also be visible, but may well contain no stars, thereby confirming a key prediction of the Cold Dark Matter (CDM) model."

[Arch2008]

Thanks Martin, but I once again require some of your insight. I thought that Weakly Interactive Massive Particles that were the candidate for DM were, well, massive (relatively speaking). This states that the plausible particle is perhaps the lightest SUSY partner of known particle species. So I'm guessing that it can be both relatively massive in comparison to known particles and still be the lightest SUSY partner?

With these discoveries, are MOND and MACHOS also still in consideration?

[Martin]

... This states that the plausible particle is perhaps the lightest SUSY partner of known particle species. So I'm guessing that it can be both relatively massive in comparison to known particles and still be the lightest SUSY partner?

With these discoveries, are MOND and MACHOS also still in consideration?

 

1. My understanding is that DM candidates are a professional specialty of Severian. You could write him PM, or try to get his attention with a thread in the particle physics forum.

 

2. I interpret Simon White's paper differently. I don't want to play guessing games about what the most plausible is. I value this paper because it proposes a test. It says that IF the dark matter is made of suchandsuch lightest Susy THEN if we look in a particular spot we will see gamma radiation. And just this year we sent up a gammaray observatory initially called GLAST and then renamed Fermi. So this is a practical doable test. We can tell Fermi to look there and if it does not see radiation that will falsify. That is cool. It is cool to rule out possibilities.

 

3. I want to stress that I don't reflect any body of expert opinion about this. I don't follow the current expert hunches about dark matter candidates. Simply for what it's worth I will tell you my personal opinion.

 

We have seen and mapped the shape of DM clouds using weak gravitational lensing. MOND is dead. MOND and MACHO don't have a prayer. There is some form of matter out there. It's not my business what it is. I have enormous respect for Simon White and his astro colleagues. And I have hopes of new physics coming from LHC results in a couple of years or anyway several years. Susy is just a conjecture and might not be true, but something new will be true. Let LHC find particles and let people like Simon White design tests to eliminate the candidates and narrow the list. Again just my personal attitude.

[Arch2008]

Thanks! I have the same attitude about MOND, MACHOS and SUSY.