Timeline for Dark Matter Particle Candidates
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
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| Feb 1, 2014 at 16:06 | comment | added | astromax | Many people believe that dark matter may in fact interact via the weak force as well, which is why a very long list of experiments have been built (and will be built) to look for this sort of signature. @jmarina, to answer your question about a "gravity telescope", you've got the right idea, but you're forgetting that light from background objects can be distorted by foreground mass - this is the basis for what's known as gravitational lensing and is currently one of our best methods of mapping out dark matter in the universe. | |
| Oct 31, 2013 at 14:26 | comment | added | jmarina | I thought dark matter does not interact except via gravity, didn't know it uses weak nuclear force as well. But that doesn't work at a distance. To see dark matter should be all about a choice of instruments. Ordinary telescopes, both earth-based and space-based, are sensitive to various parts of the electromagnetic spectrum, detecting photons emitted by cosmic objects. To see something that interacts only via gravity, a gravity telescope is needed that can see gravity waves emitted by dark matter/energy. lisa.nasa.gov is such an example. Could dark matter be non-particle things? | |
| Sep 28, 2013 at 13:53 | history | edited | astromax | CC BY-SA 3.0 |
Got rid of some unsupported statements. Answer is more to the point now.
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| Sep 27, 2013 at 20:36 | comment | added | astromax | Well - things that are composed of composite particles with charge (protons/electrons, or quarks), radiate photons. Accelerating/decelerating charged particles produce radiation, so no, there is still a fundamental difference between the two. | |
| Sep 27, 2013 at 19:16 | comment | added | Manishearth | @astromax Ah, I see. Well, the definition I've always known is that DM just needs to be nonluminous (this matches with the Wikipedia definition, though I don't trust that as much). I wouldn't say that neutron stars are made of dark matter -- I don't think that DM needs to be particulate. Instead, I'm saying that some percentage of the nonluminous gravitating matter in the universe (i.e., what I call Dark Matter) is comprised of BHs and neutrons stars and whatnot. | |
| Sep 27, 2013 at 19:12 | history | edited | Manishearth | CC BY-SA 3.0 |
added 359 characters in body
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| Sep 27, 2013 at 19:04 | comment | added | astromax | I see what you're saying, but funamentally I believe (if it does turn out to be true that DM does not interact electromagnetically, which all evidence so far points to) that you are mis-categorizing things we simply have a hard time seeing as being part of the DM of the universe. If the DM particle is found, then you would be incorrect in saying a neutron star or a brown dwarf is composed of DM - they're not. We know what they're made of. | |
| Sep 27, 2013 at 19:01 | comment | added | Manishearth | @astromax Yep, I know. I'm just saying that they're still a part (however small) of the DM. The majority of the DM (where the interesting stuff happens) is with the WIMPs and similar species. Or am I wrong in categorizing MACHOs as a type of DM? | |
| Sep 27, 2013 at 18:59 | comment | added | astromax | Though MACHOs are tough to detect (since they're very faint; e.g. - brown dwarves, neutron stars, etc..), they are certainly made of baryonic content. Some work has been done to estimate the amount of mass due to objects like these, and it still doesn't even come close to adding up. Black holes, though nobody know what happens inside of the event horizon, also do not add up to what is needed to describe what galaxy/clusters dynamics and mass reconstructions from lensing, x-ray, and S-Z measurements tell us is there. So far as we know, gravity is the only confirmed interaction. | |
| Sep 27, 2013 at 18:49 | comment | added | Manishearth | @astromax Aren't MACHOs still thought of as part of the DM in the universe? I know that they're a minority, but IIRC they still are considered DM. You're right about the neutrino bit, I planned on adding a bit but forgot. Doing so now. | |
| Sep 27, 2013 at 15:57 | comment | added | astromax | Also, can you be more specific when you say "Neutrinos". There are a number of possibilities here. | |
| Sep 27, 2013 at 15:53 | comment | added | astromax | Dark matter almost certainly does not interact in any way, shape, or form electromagnetically. For a while people thought that MACHOs were potentially the cause (whether they're brown dwarves or stellar mass black holes), but this has been ruled out through microlensing studies of the Mikly Way. However, there is a significant change that dark matter does interact via the weak force (which is why various types of neutrinos have been proposed - right-handed neutrinos, sterile neutrinos, etc..). | |
| Sep 27, 2013 at 14:58 | history | answered | Manishearth | CC BY-SA 3.0 |