Constraining the luminosity function of active galactic nuclei through the reionization observations in the SKA era

TL;DR

This paper models the impact of high-redshift AGNs on the 21-cm signal during reionization and assesses how SKA observations can constrain the AGN luminosity function with high precision.

Contribution

It introduces a radiative transfer model around high-redshift AGNs and evaluates SKA's potential to constrain the AGN luminosity function parameters.

Findings

Ionization profiles extend over 10 Mpc, observable at 10 arcmin scales.

Parameter errors are restricted to a few percent for bright high-redshift AGNs.

Future observations could further improve parameter constraints.

Abstract

Ultraviolet (UV) and X-ray photons from active galactic nuclei (AGNs) can ionize hydrogen in the intergalactic medium (IGM). We solve radiative transfer around AGNs in high redshift to evaluate the 21-cm line emission from the neutral hydrogen in the IGM and obtain the radial profile of the brightness temperature in the epoch of reionization. The ionization profile extends over 10 [Mpc] comoving distance which can be observed in the order of 10 [arcmin]. From estimation of the radio galaxy number counts with high sensitivity observation through the Square Kilometre Array (SKA), we investigate the capability of parameter constrains for AGN luminosity function with Fisher analysis for three evolution model through cosmic time. We find that the errors for each parameter are restricted to a few percent when AGNs are sufficiently bright at high redshifts. We also investigate the possibility of further parameter constraints with future observation beyond the era of SKA.