Does Increasing Luminosity Affect the Percentage of Dark Matter in a Galaxy?

In summary, the conversation discusses the potential impact of increased luminosity on the percentage of dark matter in a galaxy and whether the color of stars can also affect this percentage. The formula for calculating the mass of stars is mentioned, but it is noted that dark matter does not significantly interact with normal matter. The presence of dark matter is also said to have no apparent effect on the luminosity or spectral features of galaxies. The conversation concludes by questioning whether the presence of dark matter can impact the emission of photons.
  • #1
Huej
10
0
If luminosity increases, hypothetically, for a given galaxy, would the percentage of dark matter in that galaxy be smaller? What if the colors of the stars were to turn redder?

I was thinking if the luminosity were to increase, that would mean the percentage of the normal matters increases, thus the percentage of dark matter would decrease. But when I looked at the formula: Mass of stars: (M/L) ratio * Luminosity of stars, I was thinking the mass would be constant since the luminosities in the equation would cancel out.
 
Astronomy news on Phys.org
  • #2
Other than through gravity, 'Dark matter' only interacts very rarely with 'Normal matter', (if it does at all).
Therefore It should not significantly affect the luminosity of stars.
 
  • #3
rootone said:
Other than through gravity, 'Dark matter' only interacts very rarely with 'Normal matter', (if it does at all).
Therefore It should not significantly affect the luminosity of stars.
I don't think it's much of a interaction of dark matter and normal matter, but more of how one indirectly affects the other. So if there is higher fraction of dark matter, there would be smaller fraction of stars/gas (assuming total gravitational mass of the galaxy is constant) and impact the total luminosity. The question that I'm trying to answer does say smaller/larger, so I'm wondering which of the two, even if the impact is small. Wondering if my reasoning makes sense though.
 
  • #4
I can't think of any reason the presence of dark matter would impact luminosity. We know of galaxies with great variance in the amount of dark matter present and it apparently has no apparent effect on their luminosity or spectral features.
 
  • #5
Luminosity means the amount of photons which are getting emitted.
Apparently dark matter does not have any consequences at all for photons, (other than gravitational lensing)
... but that is by no means a dead certainty.
 
Last edited:

1. What is dark matter?

Dark matter is a type of matter that does not interact with light or other forms of electromagnetic radiation, making it invisible to telescopes and other observation tools. It is estimated to make up about 85% of the total matter in the universe.

2. How is the percentage of dark matter determined?

The percentage of dark matter is determined through various observations and calculations, such as studying the rotation of galaxies, the gravitational lensing effect, and the cosmic microwave background radiation. These methods help scientists estimate the amount of matter in the universe and how much of it is dark matter.

3. Why is dark matter important in understanding the universe?

Dark matter plays a crucial role in the structure and evolution of the universe. It helps explain the formation of galaxies and their distribution, as well as the overall expansion of the universe. Studying dark matter can also potentially lead to a better understanding of fundamental physics and the nature of gravity.

4. Can dark matter be detected?

Currently, there is no direct way to detect dark matter. However, scientists are working on various experiments and technologies to try and detect this elusive substance. Some of the proposed methods include using underground detectors, particle accelerators, and gamma-ray telescopes.

5. Is the percentage of dark matter consistent throughout the universe?

While dark matter is estimated to make up about 85% of the total matter in the universe, its distribution is not uniform. It tends to cluster around galaxies and galaxy clusters, with higher concentrations in these areas compared to the space between them. This uneven distribution is one of the challenges in studying and understanding dark matter.

Similar threads

  • Astronomy and Astrophysics
Replies
11
Views
1K
Replies
14
Views
1K
  • Astronomy and Astrophysics
Replies
21
Views
1K
  • Astronomy and Astrophysics
Replies
6
Views
2K
Replies
14
Views
2K
  • Astronomy and Astrophysics
Replies
12
Views
1K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Astronomy and Astrophysics
Replies
3
Views
855
  • Astronomy and Astrophysics
Replies
2
Views
2K
Back
Top