Calculating luminosity density of the universe

AI Thread Summary
The discussion centers on calculating the luminosity density of the universe using the Schechter parameters from the Sloan Digital Sky Survey. The user initially misinterpreted the absolute magnitude M* as the luminosity L*, leading to confusion about the relationship between the two. They acknowledged that L* should be approximately 10^10 solar luminosities. Ultimately, the user resolved their issue before the deadline. The thread highlights the importance of correctly understanding luminosity in astrophysical calculations.
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Homework Statement



l = Phi*L*Gamma(a+2)

b)

The Sloan Digital Sky Survey (SDSS) has recently measured the following Schechter
parameters in the r passband: a = -1.16 +/- 0.03, M*= -20.80 +/- 0.03, Phi* = (1.50 +/-0.13). Given that the sun has absolute magnitude M = 4.62 in the SDSS r band, calculate the luminosity density in this band in solar units. Estimate the error on this quantity.
Gamma(0.84) = 1.122, Gamma(0.81) = 1.153, Gamma(0.87) = 1.094.




Homework Equations





The Attempt at a Solution



I done the entire question and then realized i had made a grave error. And this is what I think it is; I took L* as being -20.80 +/- 0.03 ie M*, and I am pretty sure this is wrong. Luminosity confuses me and I'm not sure how to relate the absolute magnitude M* to the Luminosity L*. I know that L* is supposed to be in the order of 10^10. Can anyone out there help? Its kind of urgent (due in tomorrow!).
 
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Never mind. Problem solved
 

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