Mass to Light Ratio for Dwarf Galaxies

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Discussion Overview

The discussion revolves around the mass-to-light ratio for dwarf spheroidal galaxies, exploring methods to derive this ratio using parameters such as distance, size, absolute magnitude, and velocity dispersion. Participants are interested in understanding how to estimate the masses of these galaxies based on luminosity and related measurements.

Discussion Character

  • Exploratory, Debate/contested, Technical explanation

Main Points Raised

  • One participant inquires about methods to calculate the mass-to-light ratio using various parameters related to dwarf spheroidal galaxies.
  • Another participant expresses skepticism about the reliability of mass-to-light ratios, suggesting they are more conjectural than theoretical.
  • A different participant seeks advice on deriving mass from luminosity, indicating a desire for practical guidance.
  • It is noted that mass-to-light ratios are based on generalizations from galactic surveys, which some participants argue are approximately accurate.
  • One participant references a specific paper that presents careful measurements of mass profiles in dwarf galaxies, questioning the skepticism about the mass-to-light ratio being merely conjecture.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the reliability of mass-to-light ratios, with some viewing them as conjectural while others argue for their validity based on empirical measurements.

Contextual Notes

There are limitations regarding the assumptions made about the mass-to-light ratio and its dependence on the definitions and parameters used in the calculations. The discussion does not resolve these uncertainties.

nik6
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Hi,

I'm working on a project on dwarf spheroidal galaxies. Is there a way to get a mass-to-light ratio knowing the distance to the galaxy, its size, and maybe some other parameters like the absolute magnitude or velocity dispersion?

In the end, I'm trying to figure out their masses using this information.

Thanks!
 
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Mass to light ratio is more conjecture than theory. I would not trust any conclusions.
 
Alright I'll keep that in mind, thank you. Any advice on how to get mass from luminosity?
 
It is a generalization based on mass - luminosity ratios derived from galactic surveys. It is approximately accurate.
 
Chronos,

When i read papers like this one:
http://arxiv.org/abs/0708.0010
It seems like a fairly careful measurement of the mass profiles of several dwarf galaxies, and of course the light output can be measured directly, so the conclusion that dwarf galaxies have mass/light ratios of 10's to 100's seems sound. Why do you think it is just conjecture?
 

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