How do we detect and study dark matter in our universe?

In summary, the conversation discusses the existence and characteristics of dark matter, particularly in relation to its effects on gravitating bodies and its role in galaxy formation. The possibility of galaxies without dark matter halos is also mentioned, along with the difficulty of explaining massive galaxy formation without dark matter.
  • #1
wolram
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Isn't Dark Matter supposed to exist around ANY gravitating body, clusters, galaxies, stars, and planets? Have we ever seen a galaxy that does not seem to have a dark matter halo? If so, then it would seem that Dark Matter would have to be some sort of gravitational effect (on perhaps the zero point energy), right?
 
  • #3
Mike2 said:
Isn't Dark Matter supposed to exist around ANY gravitating body, clusters, galaxies, stars, and planets?

That will depend upon the mass of the dark matter particle. A neutrino-mass particle, for example, would have difficulty remaining bound to a star or planet. I believe that even the heaviest of proposed dark matter particles would contribute negligibly to the mass of bodies in the solar system. However, the density of such particles near the center of the sun might be large enough that they would produce an annihilation signature detectable by neutrino observatories.


Have we ever seen a galaxy that does not seem to have a dark matter halo?

There have been elliptical galaxies observed that do not appear to have dark matter:

http://www.arxiv.org/abs/astro-ph/0308518" [Broken]


If so, then it would seem that Dark Matter would have to be some sort of gravitational effect (on perhaps the zero point energy), right?

I don't see how this follows. In CDM models, I find it rather difficult to explain how a massive galaxy could be formed without dark matter.
 
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  • #4
Ditto, ST. It is very difficult to explain how massive galaxies formed so quickly in the early universe without dark matter. That, to me, is the most compelling evidence of a DM dominated universe, unless of course BBT is wrong - which would open up a kettle of fish more than a few days old.
 
  • #5
Chronos said:
Ditto, ST. It is very difficult to explain how massive galaxies formed so quickly in the early universe without dark matter. That, to me, is the most compelling evidence of a DM dominated universe, unless of course BBT is wrong - which would open up a kettle of fish more than a few days old.

That isn't quite what I meant, but is a good point. Galaxy formation is difficult in the absence of dark matter.

All I meant is that the dark matter in the early universe was well mixed with the baryonic matter. Any overdensity that collapsed into a galaxy would have contained significant quantities of both. There are methods of removing the baryonic matter (such as stellar outflows), but I don't know how a massive galaxy could shed its dark matter.
 

1. What is dark matter and why is it important to study it?

Dark matter is a type of matter that does not emit or absorb light, making it invisible to traditional telescopes. It is estimated to make up about 27% of the universe, while regular matter (such as stars and galaxies) makes up only about 5%. Studying dark matter is important because it plays a crucial role in the formation and evolution of galaxies and understanding its properties can help us better understand the universe as a whole.

2. How do dark matter detectors work?

Dark matter detectors work by looking for interactions between dark matter particles and regular matter. Most detectors use a tank of liquid, such as xenon or argon, which is surrounded by sensors. When a dark matter particle passes through the tank, it may cause a tiny flash of light or produce an electrical signal that can be detected by the sensors.

3. What are the different types of dark matter detectors?

There are several types of dark matter detectors, including direct detection, indirect detection, and collider experiments. Direct detection experiments look for interactions between dark matter and regular matter, while indirect detection experiments look for the products of dark matter annihilation or decay. Collider experiments, such as the Large Hadron Collider, aim to create dark matter particles by smashing particles together at high speeds.

4. What is the current status of dark matter detection?

Despite decades of research, dark matter has yet to be directly detected. However, there have been several promising results from various experiments, and scientists are continuously improving and developing new technologies to better detect dark matter. The search for dark matter is ongoing, and there is still much to learn about this mysterious substance.

5. What are the implications of successfully detecting dark matter?

If dark matter is successfully detected, it could provide valuable insights into the nature of the universe and its evolution. It could also help us understand the fundamental properties of matter and potentially lead to new discoveries in particle physics. Additionally, detecting dark matter could have practical applications, such as improving our understanding of gravity and potentially leading to new technologies.

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