# Natural Spectrum of the Universe?

## Answers and Replies

Physt
I assume you are interested in the relative contribution of energy density from all sources. For starlight, including energy absorbed and re-radiated by 'dust', it is comprises about 10% of the CMB energy density (re: http://condor.depaul.edu/asarma/Teaching/Spring2012/PHY475/LEC475/Lec8apr18.pdf).
Specifically I'm interested in knowing if there are any frequencies that don't occur naturally - though a graph of observed spectra would be a nice start.

Science Advisor
"Entire spectrum" of what?

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Specifically I'm interested in knowing if there are any frequencies that don't occur naturally

There are not.

Physt
There are not.
It would still be nice to have a graph of the spectrums seen with relative amplitudes.

Physt
"Entire spectrum" of what?
The EM spectrum - what this post is about.

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What part of the CMB spectrum do you find objectionable? Do you think it filters out other background contributions- like from stars and dust? If so, provide citations.

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It would still be nice to have a graph of the spectrums seen with relative amplitudes.

I am sorry that I didn't do all the work that you asked me to.

Mentor
It would still be nice to have a graph of the spectrums seen with relative amplitudes.
This will depend heavily on your position. As an example: close to a star, the stellar spectrum is a good approximation for the total flux, while far away from stars (or even from galaxies) the CMB is more important. The other energy ranges depend on your position as well.

Physt
What part of the CMB spectrum do you find objectionable? Do you think it filters out other background contributions- like from stars and dust? If so, provide citations.
Nothing whatsoever - the issue is not having a graph of the relative amplitudes by frequency.

Physt
This will depend heavily on your position. As an example: close to a star, the stellar spectrum is a good approximation for the total flux, while far away from stars (or even from galaxies) the CMB is more important. The other energy ranges depend on your position as well.
This is a fair point - I guess I'm just looking for the best average across the universe as far as we can tell at this point.

bahamagreen
http://www.pha.jhu.edu/~kgb/cosspec/ [Broken] is one for just the visual range.

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