Playground of lognormal seminumerical simulations of the Lyman <i>α</i> forest: thermal history of the intergalactic medium

Abstract This study aims to test a potential application of lognormal seminumerical simulations to recover the thermal parameters and Jeans length. This could be suitable for generating large number of synthetic spectra with various input data and parameters, and thus ideal for interpreting the high-quality data obtained from QSO absorption spectra surveys. We use a seminumerical approach to simulate absorption spectra of quasars at redshifts 3 ≤ z ≤ 5. These synthetic spectra are compared with the 1D flux power spectra and using the Markov Chain Monte Carlo analysis method, we determine the temperature at mean density, slope of the temperature-density relation and Jeans length. Our best-fit model is also compared with the evolution of the temperature of the intergalactic medium from various UVB models. We show that the lognormal simulations can effectively recover thermal parameters and Jeans length.