Mass / luminosity ratio

The mass-luminosity ratio is a value in astrophysics and physical cosmology that shows the ratio of the total mass in a given spatial volume (usually at the scale of a galaxy or cluster ) to its luminosity . Indicated by${\displaystyle \mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}$ {\ displaystyle \ Upsilon} . ^[1] As a rule, this ratio is indicated in terms of the mass-luminosity ratio for the Sun,${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}_{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\odot </span></span>}}$ {\ displaystyle \ Upsilon _ {\ odot}} = 5133 kg / W , which is equal to the ratio of the mass of the Sun to its luminosity and is a constant.

The mass-luminosity ratio for galaxies and clusters exceeds the value${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}_{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\odot </span></span>}}$ {\ displaystyle \ Upsilon _ {\ odot}} in particular, because most of the substance of such objects is not contained in stars, but observations indicate that a significant proportion of the substance is dark matter .

Luminosities are determined from photometric observations, taking into account the correction of the observed brightness for the effects of light absorption . Masses are determined by studying the dynamics of the system in the framework of virial relations or when the manifestation of the effect of gravitational lensing .

Typical mass-luminosity ratios range from 2 to 10${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}_{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\odot </span></span>}}$ {\ displaystyle \ Upsilon _ {\ odot}} , but on a larger scale, for the observable Universe, the value${\displaystyle \mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}$ {\ displaystyle \ Upsilon} reaches 100${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">{\rm Y}</span></span>}}_{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\odot </span></span>}}$ {\ displaystyle \ Upsilon _ {\ odot}} that corresponds to the Lambda-CDM model .