Thursday, December 6, 2018

cosmology - How much noise is in the Cosmic Background Radiation, especially from Cosmic Rays


Do we have an estimate of how much noise, if any, say caused by cosmic rays in particular, is present in the CMB datasets and the maps based upon them? Can we extrapolate a figure from the cosmic ray flux estimated to enter our atmosphere?


My knowledge on this subject is limited so my apologies if I have made a wrong assumption regarding the interaction, if any, between these two sources of radiation.




Answer



Cosmic Rays are most often high-energy particles, mostly protons and alpha particles accelerated to high velocities by cosmic magnetic fields. They do not show up in the microwave wavelength range that comprise the CMB.


As @ACuriousMind says in the comment, there is contamination in the CMB, but this is mainly due to Galactic dust and Bremsstrahlung from electrons in the Galactic magnetic field. This is also the reason why a broad band around the galactic plane has been masked out of the data used to calculate the anisotropies in the CMB.


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