A simulation-calibrated limit on the H i power spectrum from the GMRT Epoch of Reionization experiment

The Giant Metrewave Radio Telescope Epoch of Reionization experiment is an ongoing effort to measure the power spectrum from neutral hydrogen at high redshift. We have previously reported an upper limit of (70 mK)^2 at wavenumbers of k ≈ 0.65 h Mpc^(−1) using a basic piecewise-linear foreground subtraction. In this paper, we explore the use of a singular value decomposition to remove foregrounds with fewer assumptions about the foreground structure. Using this method, we also quantify, for the first time, the signal loss due to the foreground filter and present new power spectra adjusted for this loss, providing a revised measurement of a 2σ upper limit at (248 mK)^2 for k = 0.50 h Mpc^(−1). While this revised limit is larger than previously reported, we believe it to be more robust and still represents the best current constraint on reionization at z ≈ 8.6.

[1]  U. Pen,et al.  The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at z≈ 8.6 , 2010, 1006.1351.

[2]  Alan E. E. Rogers,et al.  The Murchison Widefield Array: Design Overview , 2009, Proceedings of the IEEE.

[3]  M. Zaldarriaga,et al.  The Growth of H II Regions During Reionization , 2004, astro-ph/0403697.

[4]  Max Tegmark,et al.  A fast method for power spectrum and foreground analysis for 21 cm cosmology , 2013 .

[5]  Bruce A. Peterson,et al.  On the Density of Neutral Hydrogen in Intergalactic Space , 1965 .

[6]  Ue-Li Pen,et al.  Can 21-cm observations discriminate between high-mass and low-mass galaxies as reionization sources? , 2011, 1107.4772.

[7]  J. Bond,et al.  Current models of the observable consequences of cosmic reionization and their detectability , 2007, astro-ph/0702099.

[8]  G. Bernardi,et al.  Subtraction of point sources from interferometric radio images through an algebraic forward modelling scheme , 2010, 1012.3719.

[9]  S. Majumdar,et al.  Constraining Quasar and IGM Properties Through Bubble Detection in Redshifted 21-cm Maps , 2011, 1111.6354.

[10]  H. Falcke,et al.  Probing the dark ages with the Square Kilometer Array , 2004 .

[11]  A. Rogers,et al.  A lower limit of Δz > 0.06 for the duration of the reionization epoch , 2010, Nature.

[12]  Max Tegmark,et al.  A model of diffuse Galactic radio emission from 10 MHz to 100 GHz , 2008, 0802.1525.

[13]  S. Oh,et al.  Systematic effects of foreground removal in 21-cm surveys of reionization , 2010, 1010.4109.

[14]  Alexander S. Szalay,et al.  Evidence for Reionization at z ∼ 6: Detection of a Gunn-Peterson Trough in a z = 6.28 Quasar , 2001, astro-ph/0108097.

[15]  M. Lueker,et al.  COSMIC MICROWAVE BACKGROUND CONSTRAINTS ON THE DURATION AND TIMING OF REIONIZATION FROM THE SOUTH POLE TELESCOPE , 2011, 1111.6386.

[16]  Steven Furlanetto,et al.  Cosmology at low frequencies: The 21 cm transition and the high-redshift Universe , 2006 .

[17]  Mervyn J. Lynch,et al.  THE PRECISION ARRAY FOR PROBING THE EPOCH OF RE-IONIZATION: EIGHT STATION RESULTS , 2009, 0904.2334.

[18]  S. Zaroubi,et al.  Power spectrum extraction for redshifted 21-cm Epoch of Reionization experiments: the LOFAR case , 2010, 1003.0965.

[19]  Abhirup Datta,et al.  BRIGHT SOURCE SUBTRACTION REQUIREMENTS FOR REDSHIFTED 21 cm MEASUREMENTS , 2010 .

[20]  S. Zaroubi,et al.  Foreground simulations for the LOFAR-epoch of reionization experiment , 2008, 0804.1130.

[21]  E. Pierpaoli,et al.  Effects of dark matter decay and annihilation on the high-redshift 21 cm background , 2006, astro-ph/0608385.

[22]  E. R. Switzer,et al.  MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z ∼ 0.8 IN CROSS-CORRELATION , 2012, 1208.0331.

[23]  Saleem Zaroubi,et al.  Foreground removal using fastica: A showcase of LOFAR-EoR , 2012, 1201.2190.

[24]  D. Kaplan,et al.  The EoR sensitivity of the Murchison Widefield Array , 2012, 1204.3111.

[25]  Martina M. Friedrich,et al.  Topology and Sizes of HII Regions during Cosmic Reionization , 2010, 1006.2016.

[26]  Martina M. Friedrich,et al.  Prospects of observing a quasar HII region during the Epoch of Reionization with redshifted 21cm , 2012, 1203.0517.

[27]  James Aguirre,et al.  A SENSITIVITY AND ARRAY-CONFIGURATION STUDY FOR MEASURING THE POWER SPECTRUM OF 21 cm EMISSION FROM REIONIZATION , 2011, 1103.2135.

[28]  A. Melchiorri,et al.  Trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity , 2008, 0801.3463.

[29]  Matias Zaldarriaga,et al.  How accurately can 21cm tomography constrain cosmology , 2008, 0802.1710.

[30]  On using visibility correlations to probe the Hi distribution from the dark ages to the present epoch – I. Formalism and the expected signal , 2004, astro-ph/0406676.

[31]  J. Hewitt,et al.  Toward Empirical Constraints on the Global Redshifted 21 cm Brightness Temperature During the Epoch of Reionization , 2007, 0710.2541.

[32]  Cathryn M. Trott,et al.  THE IMPACT OF POINT-SOURCE SUBTRACTION RESIDUALS ON 21 cm EPOCH OF REIONIZATION ESTIMATION , 2012, 1208.0646.

[33]  Edward J. Wollack,et al.  FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION , 2008, 0803.0547.

[34]  Foregrounds for 21-cm observations of neutral gas at high redshift , 2003, astro-ph/0302099.

[35]  A. Melchiorri,et al.  Data-constrained reionization and its effects on cosmological parameters , 2011, 1111.3570.

[36]  M. Kamionkowski,et al.  Galaxy-Cluster Masses via 21st-Century Measurements of Lensing of 21-cm Fluctuations , 2012, 1210.3041.

[37]  G. Mellema,et al.  The inhomogeneous reionization of the local intergalactic medium by metal-poor globular clusters , 2012, Monthly Notices of the Royal Astronomical Society.

[38]  David F. Moore,et al.  A PER-BASELINE, DELAY-SPECTRUM TECHNIQUE FOR ACCESSING THE 21 cm COSMIC REIONIZATION SIGNATURE , 2012, 1204.4749.

[39]  On the Threshold of the Reionization Epoch , 2001, astro-ph/0108069.

[40]  Max Tegmark,et al.  A method for 21 cm power spectrum estimation in the presence of foregrounds , 2011, Physical Review D.

[41]  Xiaohui Fan,et al.  The first (nearly) model-independent constraint on the neutral hydrogen fraction at z ∼ 5–6 , 2011, 1101.3314.

[42]  The morphology of H ii regions during reionization , 2006, astro-ph/0610094.

[43]  Zoltan Haiman,et al.  Fossil H ii regions: self-limiting star formation at high redshift , 2003 .

[44]  Z. Haiman.  Cosmology: A smoother end to the dark ages , 2011, Nature.

[45]  Matias Zaldarriaga,et al.  Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization , 2005, astro-ph/0512263.

[46]  J. Chengalur,et al.  Foregrounds for redshifted 21-cm studies of reionization: Giant Meter Wave Radio Telescope 153-MHz observations , 2008, 0801.2424.

[47]  Matias Zaldarriaga,et al.  Simulations and Analytic Calculations of Bubble Growth during Hydrogen Reionization , 2006, astro-ph/0604177.

[48]  Max Tegmark,et al.  How well can we measure and understand foregrounds with 21-cm experiments? , 2011, 1106.0007.

[49]  J. Prasad,et al.  Characterizing foreground for redshifted 21 cm radiation: 150 MHz Giant Metrewave Radio Telescope observations , 2012, 1208.1617.

[50]  J. Schaye,et al.  Imaging neutral hydrogen on large scales during the Epoch of Reionization with LOFAR , 2012, 1205.3449.