On the Nature of the Small-scale Structure in the Cosmic Microwave Background Observed by PLANCK and WMAP

Abstract

Small-scale features observed by Wilkinson Microwave Anisotropy Probe (WMAP) and PLANCK in the frequency range of 22-90 GHz show a nearly flat spectrum, which meets with expectations that they originate in the early universe. However, free-free emission from electrons in small angular scale galactic sources that suffer beam dilution very closely mimic the observed spectrum in this frequency range. Fitting such a model to the PLANCK and WMAP data shows that the angular size required to fit the data is comparable to the angular width of associated H I filaments found in the Galactic Arecibo L-Band Feed Array-H isurvey data. Also, the temperature of the electrons is found to be in the range of 100-300 K. The phenomenon revealed by these data may contribute to a more precise characterization of the foreground masks required to interpret the cosmological aspect of PLANCK and WMAP data.