Abstract
Several experiments are underway to detect the cosmic-redshifted 21-cm signal from neutral hydrogen from the Epoch of Reionization (EoR). Due to their very low signal-to-noise ratio, these observations aim for a statistical detection of the signal by measuring its power spectrum. We investigate the extraction of the variance of the signal as a first step towards detecting and constraining the global history of the EoR. Signal variance is the integral of the signal’s power spectrum, and it is expected to be measured with a high significance. We demonstrate this through results from a simulation and parameter estimation pipeline developed for the Low-Frequency Array (LOFAR)-EoR experiment. We show that LOFAR should be able to detect the EoR in 600 h of integration using the variance statistic. Additionally, the redshift (zr) and duration (Δz) of reionization can be constrained assuming a parametrization. We use an EoR simulation of zr = 7.68 and Δz = 0.43 to test the pipeline. We are able to detect the simulated signal with a significance of four standard deviations and extract the EoR parameters as z_r = 7.72^{+0.37}_{-0.18} and Δ z = 0.53^{+0.12}_{-0.23} in 600 h, assuming that systematic errors can be adequately controlled. We further show that the significance of detection and constraints on EoR parameters can be improved by measuring the cross-variance of the signal by cross-correlating consecutive redshift bins.
Author
Patil, Ajinkya H.; Zaroubi, Saleem; Chapman, Emma; Jelić, Vibor; Harker, Geraint; Abdalla, Filipe B.; Asad, Khan M. B.; Bernardi, Gianni; Brentjens, Michiel A.; de Bruyn, A. G.; Bus, Sander; Ciardi, Benedetta; Daiboo, Soobash; Fernandez, Elizabeth R.; Ghosh, Abhik; Jensen, Hannes; Kazemi, Sanaz; Koopmans, Léon V. E.; Labropoulos, Panagiotis; Mevius, Maaijke; Martinez, Oscar; Mellema, Garrelt; Offringa, Andre R.; Pandey, Vishhambhar N.; Schaye, Joop; Thomas, Rajat M.; Vedantham, Harish K.; Veligatla, Vamsikrishna; Wijnholds, Stefan J.; Yatawatta, Sarod
Journal
Monthly Notices of the Royal Astronomical Society
Paper Publication Date
September 2014
Paper Type
Astrostatistics