The discussion revolves around the concept of the natural spectrum of bodies in the universe, including contributions from various astronomical sources such as stars, black holes, and cosmic microwave background (CMB) radiation. Participants explore the idea of compiling a comprehensive spectrum that represents these contributions across different frequencies.
Participants express differing views on the existence of frequencies that do not occur naturally, with some asserting there are none while others seek clarification. The discussion remains unresolved regarding the best average spectrum across the universe and the implications of position on observed spectra.
Participants note that the contributions to the spectrum can vary significantly based on the observer's location in relation to different astronomical bodies, indicating a dependence on specific conditions and assumptions.
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.Chronos said: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).
Physt said:Specifically I'm interested in knowing if there are any frequencies that don't occur naturally
It would still be nice to have a graph of the spectrums seen with relative amplitudes.Vanadium 50 said:There are not.
The EM spectrum - what this post is about.bapowell said:"Entire spectrum" of what?
Physt said: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 said:It would still be nice to have a graph of the spectrums seen with relative amplitudes.
Nothing whatsoever - the issue is not having a graph of the relative amplitudes by frequency.Chronos said: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.
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.mfb said: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.