Constraining the epoch of reionization with the variance statistic: simulations of the LOFAR case

• Published in: arXiv.org
• Main Authors: 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
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 16.06.2014
• Subjects: Constraining; Ionization; LOFAR; Parameter estimation; Parameterization; Physics - Cosmology and Nongalactic Astrophysics; Red shift; Simulation; Statistical analysis; Systematic errors; Variance
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1401.4172

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 hours of integration using the variance statistic. Additionally, the redshift (\(z_r\)) and duration (\(\Delta z\)) of reionization can be constrained assuming a parametrization. We use an EoR simulation of \(z_r = 7.68\) and \(\Delta z = 0.43\) to test the pipeline. We are able to detect the simulated signal with a significance of 4 standard deviations and extract the EoR parameters as \(z_r = 7.72^{+0.37}_{-0.18}\) and \(\Delta z = 0.53^{+0.12}_{-0.23}\) in 600 hours, 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.