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1 vote
1 answer
173 views

How can I convert luminosity from [erg/s/Hz] to [erg/s]

I have the dust-corrected luminosity in the Ks band in the unit erg/s/Hz. I want to convert it to erg/s. I would like to know which method is correct: $L[erg/s]=L[erg/s/Hz]\times(C/\lambda)$ $L[erg/s]...
Fatemeh Abedini's user avatar
15 votes
6 answers
4k views

What's the issue with Olbers' paradox?

I'm not quite grasping the reasoning behind Olbers' Paradox, or why an eternal, non-expanding and spatially infinite universe would be incompatible with a dark sky. For simplicity, let's suppose that ...
Alex Popescu's user avatar
4 votes
1 answer
3k views

How to correct observed flux densities for redshift

Say I have a spectrum of a galaxy at a redshift $z$, in flux density units of erg/s/cm^2/Angstrom. I'd like to recover the spectrum (in the same flux density units) at z=0, i.e. at its rest ...
curious_cosmo's user avatar
3 votes
0 answers
197 views

What is the spectral power output of a typical galaxy?

I'm looking for a function which gives the typical isotropic spectral power of light emitted by an entire galaxy on the whole electromagnetic spectrum (in watts per frequency unit), as a function of ...
Cham's user avatar
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