Neutrino Signatures on the High Transmission Regions of the Lyman-alpha Forest

Understand

We quantify the impact of massive neutrinos on the statistics of low density regions in the intergalactic medium (IGM) as probed by the Lyman-alpha forest at redshifts z=2.2--4.

• Based on mock but realistic quasar (QSO) spectra extracted from hydrodynamic simulations with cold dark matter, baryons and neutrinos, we find that the probability distribution of weak Lyman-alpha absorption features, as sampled by Lyman-alpha flux regions at high transmissivity, is strongly affected by the presence of massive neutrinos.
• We show that systematic errors affecting the Lyman-alpha forest reduce but do not erase the neutrino signal.
• Using the Fisher matrix formalism, we conclude that the sum of the neutrino masses can be measured, using the method proposed in this paper, with a precision smaller than 0.4 eV using a catalog of 200 high resolution (S/N~100) QSO spectra.