The Impact of Realistic Foreground and Instrument Models on 21 cm Epoch of Reionization Experiments
Abstract
Predictions for the ability of 21 cm interferometric experiments to discriminate Epoch of Reionization (EoR) signal models are typically limited by the simplicity of data models, whereby foreground signals and characteristics of the instrument are often simplified or neglected. To move toward more realistic scenarios, we explore the effects of applying more realistic foreground and instrument models to the 21 cm signal, as well as the ability to estimate astrophysical parameters with these additional complexities. We use a highly optimized version of 21cm FAST, integrated into 21cm MC, to generate lightcones of the brightness temperature fluctuation for Bayesian parameter estimation. We include a statistical pointsource foreground model and an instrument model based on the Murchison Widefield Array scaled in observation time to have an effective sensitivity similar to the future Square Kilometre Array. We also extend the current likelihood prescription to account for the presence of beam convolution and foregrounds, the twodimensional power spectrum (PS), and the correlation of PS modes. We use frequency bands between 150 and 180 MHz to constrain the ionizing efficiency (ζ), the minimum virial temperature of halos ( ${T}_{\mathrm{vir}}$ ), the soft Xray emissivity per unit star formation rate (SFR) (L_{X}/SFR), and the Xray energy threshold (E_{0}). We find that the inclusion of realistic foregrounds and instrumental components biases the parameter constraints, due to unaccounted for crosspower between the EoR signal, foregrounds, and thermal noise. This causes estimates of ζ to be biased by up to 5σ, but the estimates of T_{vir}, L_{X}/SFR and E_{0} remain unaffected and are all within 1σ.
 Publication:

The Astrophysical Journal
 Pub Date:
 April 2020
 DOI:
 10.3847/15384357/ab8003
 arXiv:
 arXiv:2003.08552
 Bibcode:
 2020ApJ...893..118N
 Keywords:

 Reionization;
 Cosmology;
 Largescale structure of the universe;
 Astronomical instrumentation;
 1383;
 343;
 902;
 799;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 doi:10.3847/15384357/ab8003