Disentangling the growth rate of perturbations from the HI bias using only clustering data from galaxy surveys

Abstract

This work serves two-fold purpose. Firstly, we provide an alternative to the traditional method of determining the growth rate of density perturbations . In usual practice, can not be directly measured from tracer clustering at some redshift without knowledge of the bias. While the bayron acoustic oscillation (BAO) imprint allows the determination of , redshift space anisotropy (RSD) allows the measurement of a quantity . To extract from , one usually requires some other data set. We show that precise BAO and RSD measurements in and around some key redshifts themselves can solely reconstruct without requiring any other data sets. Secondly, we extend this approach to another tracer, namely the post-reionization 21-cm brightness temperature intensity maps. We demonstrate that the measured from purely redshift space clustering allows us to measure the 21-cm bias, which is a largely unknown quantity. This may help interpret the observed intensity mapping signal in the future.