Prospects of FRBs and Large Scale 21 cm Power Spectra in Constraining the Epoch of Reionization

TL;DR

This paper investigates how combining Fast Radio Burst dispersion measures and large-scale 21 cm power spectra can improve constraints on the timing and progression of the Epoch of Reionization, using semi-numerical modeling.

Contribution

It demonstrates that joint analysis of FRB DMs and 21 cm spectra can significantly tighten constraints on reionization history and thermal evolution.

Findings

100 mock FRBs can recover reionization models within uncertainties.

1000 FRB mocks constrain reionization timeline within 8%.

Joint analysis reduces parameter degeneracies.

Abstract

The Epoch of Reionization (EoR) is a crucial link to grasp the complete evolutionary history of the universe. Several attempts with a variety of observables have been utilized in the past to understand the thermal and ionization evolution of the Intergalactic Medium during EoR. In this study, we explore the simultaneous prospects of two important observables which are expected to be available in the near future, i.e. Dispersion Measure (DM) of high redshift FRBs and large scale 21 cm power spectra. For this purpose, we use an earlier developed explicitly photon conserving semi numerical model, $\texttt{SCRIPT}$ including realistic recombination and radiative feedback effect. We check that DM evolution of 100 mock FRBs at high redshifts ($7.0\le z\le15.0$) is sufficient to recover the underlying reionization model, while 1000 FRB mocks at redshift range can constrain the reionization timeline within the percentage level uncertainties at 68\% confidence limit. Further, we study the effect of including large scale 21~cm power spectra (using only a single bin, $k\sim0.14~h/\mathrm{cMpc}$) at three redshifts along with FRB DM distribution. The joint exploration using these two observables can significantly improve the constraints on the various parameters ($\lesssim 8\%$ uncertainties for reionization interval and midpoint at 95\% confidence) alleviating the degeneracies and can narrow down the thermal history of the universe by discarding some of the extreme heating models.