Effect of magnetic seed fields on Lyman Alpha emission from distant quasars

Abstract

There are indications that weak magnetic fields originating in the early Universe and magnified via magnetohydrodynamic (MHD) processes could cause perturbations in the thermodynamic state of the gas in the intergalactic medium which affect the Lyman-Alpha spectrum we observe. In this work we investigate to what extent the properties of the Lyman-Alpha forest are sensitive to the presence of large-scale cosmological magnetic fields as a function of the seed field intensity. To do so, we develop and use a series of numerical tools to analyze previously constructed cosmological MHD simulations that include state-of-the-art implementation of the relevant physical processes for galaxy formation. The inclusion of these physical mechanisms is crucial to get the level of magnetic field amplification currently observed in the structures that populate our Universe. With these tools we isolate characteristics, namely the Flux Probability Density Function and the Power Spectrum, of the Lyman-Alpha forest that are sensitive to the magnetic field strength. We then examine the implications of our results.