SKA-Low simulations for a cosmic dawn/epoch of reionisation deep field

TL;DR

This paper presents a detailed simulation of SKA-Low observations during the cosmic dawn and epoch of reionisation, including realistic sky components, errors, and data products to aid foreground mitigation research.

Contribution

It provides a comprehensive, realistic simulation framework for SKA-Low CD/EoR observations, including errors and data products, to support development of foreground mitigation methods.

Findings

Simulated observations include CD/EoR signal, foregrounds, and Galactic emission.

Errors such as de-mixing, calibration, and ionospheric effects are modeled.

The simulation supports assessment of foreground mitigation techniques.

Abstract

We present a realistic simulation of an SKA-Low cosmic dawn/epoch of reionisation (CD/EoR) observation, which can be used to further the development of foreground-mitigation approaches. The simulation corresponds to a deep (1000 h) integration pointing over the 106 MHz-196 MHz frequency range. The sky components include the CD/EoR signal, extragalactic foreground emission featuring strong (over 5 Jy at 150 MHz) out-of-field sources and in-field sources down to 1 microJy at 150 MHz, and Galactic emission from the GSM2016 model complemented with small-scales structure beyond its native $\sim 1$ deg resolution from a magneto-hydrodynamic simulation of the interstellar medium. Modeled errors include a partial de-mixing of the out-of-field sources, direction-dependent calibration errors leading to residual ionospheric effects, and direction-independent gain calibration errors, on top of thermal noise. Simulated observations are delivered as visibilities as well as imaging products with natural weighting. The true, uncorrupted, CD/EoR signal is also delivered, to allow an assessment of the efficacy of foreground-mitigation approaches. The codes used to generate these simulations are also delivered, so that new simulated datasets can be produced. This simulation has been the basis for the SKA Science Data Challenge 3a (SDC3a), which addressed foreground removal.