TY - JOUR

T1 - Constraining the epoch of reionization with the variance statistic

T2 - Simulations of the LOFAR case

AU - Patil, Ajinkya H.

AU - Zaroubi, Saleem

AU - Chapman, Emma

AU - Jelić, Vibor

AU - Harker, Geraint

AU - Abdalla, Filipe B.

AU - Asad, Khan M.B.

AU - Bernardi, Gianni

AU - Brentjens, Michiel A.

AU - de Bruyn, A. G.

AU - Bus, Sander

AU - Ciardi, Benedetta

AU - Daiboo, Soobash

AU - Fernandez, Elizabeth R.

AU - Ghosh, Abhik

AU - Jensen, Hannes

AU - Kazemi, Sanaz

AU - Koopmans, Léon V.E.

AU - Labropoulos, Panagiotis

AU - Mevius, Maaijke

AU - Martinez, Oscar

AU - Mellema, Garrelt

AU - Offringa, Andre R.

AU - Pandey, Vishhambhar N.

AU - Schaye, Joop

AU - Thomas, Rajat M.

AU - Vedantham, Harish K.

AU - Veligatla, Vamsikrishna

AU - Wijnholds, Stefan J.

AU - Yatawatta, Sarod

PY - 2014/4

Y1 - 2014/4

N2 - 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 zr = 7.72+0.37 -0.18 and Δz = 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.

AB - 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 zr = 7.72+0.37 -0.18 and Δz = 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.

KW - Dark ages, reionization, first stars

KW - Methods: statistical

KW - Techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=84905641386&partnerID=8YFLogxK

U2 - 10.1093/mnras/stu1178

DO - 10.1093/mnras/stu1178

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AN - SCOPUS:84905641386

SN - 0035-8711

VL - 443

SP - 1113

EP - 1124

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -