Dark Matter Mass: Evidence of Low-Mass?

In summary, the conversation discusses the indication of dark matter having a low-mass compared to visible matter, as well as the use of gravitational lensing to study dark matter. It is mentioned that there are viable dark matter candidates in a wide range of masses, but micro-lensing rules out some range of masses for massive objects. The question of comparing the volumes of visible and dark matter is also brought up, with the conclusion that in the galaxy as a whole, there is more dark matter, while on Earth there is more baryonic matter. The lack of low angle scattering in microlensing suggests that dark matter is divided into large but low and smooth density lumps.
  • #1
Ranku
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Is there any indication, such as through gravitational lensing, that dark matter has a low-mass compared to visible matter?
 
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  • #2
Are you referring to the dark matter particle mass or the total mass of dark matter?

In the first case no, you have viable dark matter candidates in a very large span of masses. In the second, the total mass of dark matter in the Universe is about five times that of normal matter.
 
  • #3
Orodruin said:
Are you referring to the dark matter particle mass or the total mass of dark matter?
I meant in the first case. Does gravitational lensing indicate anything, one way or another?
 
  • #4
Ranku said:
I meant in the first case. Does gravitational lensing indicate anything, one way or another?
Micro-lensing rules out some range of masses for quite massive objects such as primordial black holes. When it comes to fundamental particle candidates, it does not.
 
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  • #5
Ranku said:
Is there any indication, such as through gravitational lensing, that dark matter has a low-mass compared to visible matter?

I think you need to clarify this question. How much are we talking about? A kilogram of each weighs the same, no?
 
  • #6
Vanadium 50 said:
I think you need to clarify this question. How much are we talking about? A kilogram of each weighs the same, no?
I mean in terms of comparable volumes of visible and dark matter - although not sure how practically feasible it is to compare between volumes.
 
  • #7
In the galaxy as a whole, there is more dark matter. In the earth, there is more baryonic matter.
 
  • #8
If there were dense lumps of dark matter then microlensing of light by such dense lumps of dark matter would show up as low angle scattering.
Absence of such low angle scattering suggests lack of lumps of certain sizes, and that dark matter is divided into big but low and smooth density lumps.
 
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1. What is dark matter and why is it important?

Dark matter is a hypothetical form of matter that is thought to make up approximately 85% of the total matter in the universe. It is called "dark" because it does not interact with light and therefore cannot be seen directly. Its existence is inferred through its gravitational effects on visible matter. Understanding dark matter is important because it plays a crucial role in the structure and evolution of the universe.

2. How is the mass of dark matter determined?

The mass of dark matter is determined through various methods, such as gravitational lensing, galaxy rotation curves, and the cosmic microwave background. These methods measure the gravitational effects of dark matter on visible matter and use mathematical models to estimate its mass.

3. What is the evidence for low-mass dark matter?

There are several lines of evidence that suggest the existence of low-mass dark matter. One is the observed rotation curves of galaxies, which show that there is more mass present than can be accounted for by visible matter. Another is the fluctuations in the cosmic microwave background, which indicate the presence of cold dark matter particles. Additionally, simulations of the evolution of the universe support the existence of low-mass dark matter.

4. How does the mass of dark matter affect the formation of galaxies?

The mass of dark matter has a significant impact on the formation of galaxies. It provides the gravitational pull necessary to form and maintain the large-scale structures of the universe, such as galaxies and galaxy clusters. The distribution of dark matter also influences the distribution of visible matter, as it acts as a scaffolding for the formation of galaxies.

5. What are the implications of low-mass dark matter for particle physics?

The existence of low-mass dark matter may have implications for particle physics, as it could potentially be made up of new, yet undiscovered particles. Studying the properties of dark matter can provide insights into the fundamental nature of matter and the laws of physics. It also presents a potential avenue for further exploration and discovery in the field of particle physics.

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