A New Model for the Extragalactic Radio Sky at Low Frequency Calibrated Using the LOFAR Two-metre Survey

TL;DR

This paper presents a recalibrated model of the low-frequency extragalactic radio sky using LOFAR data, improving source count predictions and aiding cosmological studies like the Epoch of Reionization.

Contribution

The authors recalibrated the radio luminosity functions for various source types and updated the T-RECS simulation to produce more accurate mock catalogs at low frequencies.

Findings

Simulated source counts match observed data at high redshifts ($z>4$).

Differential source counts in the 0.1-1 mJy flux range align with observations.

The model predicts a lower power spectrum for point sources, beneficial for low-frequency cosmology.

Abstract

Building the radio sky template are crucial for detecting the 21 cm emission line signal from the Epoch of Reionization (EoR), as well as for other cosmological research endeavors. Utilizing data from the LOFAR Two-meter Sky Survey (LoTSS) at 150 MHz, we recalibrated the luminosity function for various types of radio sources, including High Excitation Radio Galaxies (HERGs), Low Excitation Radio Galaxies (LERGs), Radio-Quiet Active Galactic Nuclei (RQ-AGNs), and Star-Forming Galaxies (SFGs). We subsequently updated the Tiered Radio Extragalactic Continuum Simulation (T-RECS) code to generate refined mock radio source catalogues. The simulated source counts from this work align more closely with observed data at redshifts greater than $z>4$. Additionally, the differential source counts in total intensity within the flux density range of $0.1-1~\mathrm{mJy}$ closely mirror actual observations. Due to our model incorporating a lower number of faint sources compared to T-RECS, it predicts a reduced power spectrum for point sources, suggesting a potential advantage in studies in low frequency band.