Faber-Jackson Relation: Explained | Shounak

In summary, the conversation discusses various relations used to calculate the correlation between luminosity and velocity dispersion in different types of galaxies. The Faber Jackson relation establishes a direct relationship between the two in elliptical galaxies, while the Tully-Fisher relation explains this correlation in spiral galaxies. The Tully-Fisher model is similar to the Faber Jackson relation but is used for spiral galaxies. The conversation also mentions the use of a different model for calculating irregular galaxies.
  • #1
shounakbhatta
288
1
Hello,

What does the Faber Jackson relation tells?
Does it establish the relation between: higher the Luminosity, higher the velocity dispersion?

Does it calculate in Elliptical galaxies?

What does Tully-Fisher relation explains?

-- Shounak
 
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  • #2
Is Faber Jackson relation shows a directly proportional relation to the velocity dispersion?
 
  • #3
Can somebody please explain the derivation of the equation L <alpha> sigma times gamma?
 
  • #4
Is Tully Fisher model used in calculating the relation between luminosity and dispersion velocity in spiral galaxy?

Is Tully Fisher model and Faber Jackson are same except they are used in spiral and elliptical galaxy?

What model is used to calculate irregular galaxies?
 
  • #5
Easy buddy, one question at a time. Give the thread a few days for someone to reply before bumping it back up.
 

1. What is the Faber-Jackson Relation?

The Faber-Jackson Relation is an empirical relation between the central velocity dispersion and the absolute luminosity of elliptical galaxies. It was discovered in 1976 by astronomers Sandra Faber and Robert Jackson and is widely used to estimate the mass of elliptical galaxies.

2. How is the Faber-Jackson Relation derived?

The Faber-Jackson Relation is derived by plotting the central velocity dispersion (σ) against the absolute luminosity (L) for a sample of elliptical galaxies. The data is then fit with a power law relation, typically of the form L∝σ^4. This relation is found to be valid over a wide range of luminosities and central velocity dispersions.

3. What is the significance of the Faber-Jackson Relation?

The Faber-Jackson Relation is significant because it allows astronomers to estimate the mass of elliptical galaxies without directly measuring their mass. This is important because the mass of a galaxy is a crucial factor in understanding its formation and evolution.

4. Are there any limitations to the Faber-Jackson Relation?

While the Faber-Jackson Relation is a useful tool for estimating the mass of elliptical galaxies, it has some limitations. It is only valid for elliptical galaxies and does not apply to spiral or irregular galaxies. Additionally, the relation may be affected by various factors such as mergers, interactions with other galaxies, and non-uniformities in the galaxy's structure.

5. How has the Faber-Jackson Relation contributed to our understanding of galaxies?

The Faber-Jackson Relation has greatly contributed to our understanding of galaxies by providing a way to estimate their mass. This has allowed astronomers to study the relationship between mass and other properties of galaxies, such as size and shape, and gain insights into their formation and evolution. It has also been used to investigate the role of dark matter in galaxies, as the relation suggests that the majority of a galaxy's mass is made up of dark matter.

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