# Why is the DM density near the sun so small?

• I
• Buzz Bloom
In summary, the conversation discusses the estimated value for the density of dark matter near the sun and the average density of dark matter in the universe. It is noted that the average density is significantly lower than the local density, with a difference of 4.5 orders of magnitude. A reference is also provided for further information on astrophysical constants.
Buzz Bloom
Gold Member
This question arose in the context of another thread.
Wikipedia gives an estimated value for the DM density near the sun of
0.35 × GeV/cm3 = 6.2 ×10−25 g/cm3.​
The value of the average DM density in the universe
ρDM = 2.26 ×10−24 g/cm3.
https://en.wikipedia.org/wiki/Milky_Way - Bottom of list of Observation data​
This means that ρDM is approximately 3.6 times the density of DM near the sun.

I unsuccessfully have tried to find references that provide an answer to the question, but my skills are not up to the challenge. I am hopeful that one or more knowledgeable participants here the PFs can help me.

Regards,
Buzz

Last edited:
The average density in the universe is 2.26*10-30 g/cm3, 4.5 orders of magnitude thinner than the local density. I guess you mixed cm3 and m3, as the number is equal to 2.26*10-24 g/m3.

http://pdg.ge.infn.it/2015/reviews/rpp2014-rev-astrophysical-constants.pdf

Buzz Bloom
Hi @mfb:
Thank you very much for spoting and letting me know about my careless error.

Regards,
Buzz

1)

## Why is the DM density near the sun so small?

The DM density near the sun is small because dark matter is distributed evenly throughout the universe, and the sun is just one small part of it. This means that the amount of dark matter in the vicinity of the sun is relatively low compared to other regions of the universe.

2)

## What is dark matter and why is it important?

Dark matter is a type of matter that does not interact with light and therefore cannot be seen or directly detected. It is important because it makes up about 85% of the total mass of the universe and plays a crucial role in the formation and evolution of galaxies.

3)

## Why is the DM density near the sun different from other regions?

The DM density near the sun is not necessarily different from other regions, but it may appear to be smaller because the sun is located in the outskirts of the Milky Way galaxy. This means that it is not as densely packed with dark matter as the central regions of the galaxy.

4)

## Could the DM density near the sun change in the future?

It is possible that the DM density near the sun could change in the future, as the distribution of dark matter is constantly evolving and influenced by the gravitational pull of other objects. However, any changes would likely be very gradual and difficult to detect.

5)

## How do scientists measure the DM density near the sun?

Scientists use a variety of techniques to indirectly measure the DM density near the sun, such as observing the gravitational effects of dark matter on the motion of stars and galaxies. They also use computer simulations and models to estimate the distribution of dark matter in different regions of the universe.

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