Journal Article

The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at <i>z</i>≈ 8.6

Gregory Paciga, Tzu-Ching Chang, Yashwant Gupta, Rajaram Nityanada, Julia Odegova, Ue-Li Pen, Jeffrey B. Peterson, Jayanta Roy and Kris Sigurdson

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 413, issue 2, pages 1174-1183
Published in print May 2011 | ISSN: 0035-8711
Published online April 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18208.x
The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at z≈ 8.6

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We present a new upper limit to the 21-cm power spectrum during the Epoch of Reionization (EoR) which constrains reionization models with an unheated IGM. The GMRT-EoR experiment is an ongoing effort to make a statistical detection of the power spectrum of 21-cm neutral hydrogen emission at redshift z∼ 9. Data from this redshift constrain models of the EoR, the end of the Dark Ages arising from the formation of the first bright UV sources, probably stars or mini-quasars. We present results from approximately 50 h of observations with the Giant Metrewave Radio Telescope in India from 2007 December. We describe radio-frequency interference (RFI) localization schemes which allow bright sources on the ground to be identified and physically removed in addition to automated flagging. Singular-value decomposition is used to remove the remaining broad-band RFI by identifying ground sources with large eigenvalues. Foregrounds are modelled using a piecewise linear filter and the power spectrum is measured using cross-correlations of foreground-subtracted images.

Keywords: intergalactic medium; cosmology: observations; dark ages, reionization, first stars; diffuse radiation; radio lines: general

Journal Article.  7977 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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