On the effect of cosmic rays in bolometric CMB measurements from the
  stratosphere
  Ultra-sensitive bolometric detectors in balloon-borne or satellite missions
have the potential to discover low-level non gaussian features in the Cosmic
Microwave Background (CMB), due to topological defects or to the inflation
process. However, the space environment includes a population of cosmic rays
(CR), which produce spurious spikes in bolometric signals. In this paper we
analyze how CR affect these measurements and the estimates of non-gaussianity
and of angular power spectra of the CMB. Using accurate simulations of noise
and CR events in bolometric detectors, we find that a de-spiking technique
based on outliers removal in the detector signals contributing to the same sky
pixel works well in removing CR events larger than the noise. Low level events
hidden in the noise produce skewness and kurtosis of the temperatures of the
pixels, indicating low-level non-gaussianity. Moreover, when the low-level CR
distribution is not known a-priori, the standard noise estimation pipeline
produces a positive bias of the power spectrum at high multipoles. In
experiments with detector sensitivity better than 100 $\mu K / \sqrt{Hz}$, in
an environment less favorable than the earth stratosphere, the CR-induced non
gaussianity is likely to affect significantly the results.
