Can we constrain the evolution of HI bias using configuration entropy?

Abstract

We study the evolution of the configuration entropy of HI distribution in the post-reionization era assuming different time evolution of HI bias. We describe time evolution of linear bias of HI distribution using a simple form b(a) = b0a n with different index n. The derivative of the configuration entropy rate is known to exhibit a peak at the scale factor corresponding to the Λ-matter equality in the unbiased ΛCDM model. We show that in the ΛCDM model with time-dependent linear bias, the peak shifts to smaller scale factors for negative values of n. This is related to the fact that the growth of structures in the HI density field can significantly slow down even before the onset of Λ domination in the presence of a strong time evolution of the HI bias. We find that the shift is linearly related to the index n. We obtain the best fit relation between these two parameters and propose that identifying the location of this peak from observations would allow us to constrain the time evolution of HI bias within the framework of the ΛCDM model