Pregalactic 4He abundance with new data on systematic errors in its determination

Primordial helium abundance in the universe was determined based on spectral observations of low-metallicity blue compact dwarf galaxies. The intensities of the observed emission lines were corrected for several mechanisms, including stellar absorption and collisional excitation of the helium and hydrogen emission spectra. Parameters that were necessary for correcting the deviations of the emission lines’ intensities from their recombination values were determined using the Monte Carlo method. The obtained value of primordial helium of 0.2557 ± 0.0014 is higher by 3% than the value obtained from the analysis of the microwave background radiation fluctuations under the assumption of the standard model of primordial nucleosynthesis. This points to the existence of new types of neutrino in the primordial nucleosynthesis epoch, in addition to the three known ones.