Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR

We present the first limits on the Epoch of Reionization 21 cm H I power spectra, in the redshift range z = 7.9–10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero Δ^2_I = (56 ± 13 mK)^2 (1-σ) excess variance and a best 2-σ upper limit of Δ^2_(21) < (79.6 mK)^2 at k = 0.053 h cMpc^(−1) in the range z = 9.6–10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.

[1]  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.

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

[3]  N. Lomb.  Least-squares frequency analysis of unequally spaced data , 1976 .

[4]  Jan Noordam,et al.  Radio Interferometric Calibration Using The SAGE Algorithm , 2008, DSP 2009.

[5]  Saleem Zaroubi,et al.  Constraints on reionization from the thermal history of the intergalactic medium , 2002 .

[6]  Mohamed-Jalal Fadili,et al.  Sparsity and Morphological Diversity in Blind Source Separation , 2007, IEEE Transactions on Image Processing.

[7]  L. Koopmans,et al.  Scintillation noise power spectrum and its impact on high redshift 21-cm observations , 2015, 1512.00159.

[8]  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.

[9]  A. R. Whitney,et al.  The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies , 2012, Publications of the Astronomical Society of Australia.

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

[11]  S. Markoff,et al.  LOFAR - low frequency array , 2006 .

[12]  David F. Moore,et al.  PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM AT z = 8.4 , 2015, 1502.06016.

[13]  Jean-Luc Starck,et al.  Morphological diversity and sparsity: new insights into multivariate data analysis , 2007, SPIE Optical Engineering + Applications.

[14]  M. Morales,et al.  Reionization and Cosmology with 21-cm Fluctuations , 2009, 0910.3010.

[15]  Melbourne.,et al.  Measurements of the UV background at 4.6 < z < 6.4 using the quasar proximity effect , 2010, 1011.5850.

[16]  O. Smirnov.  Revisiting the radio interferometer measurement equation. I. A full-sky Jones formalism , 2011, 1101.1764.

[17]  W. Sargent,et al.  A first direct measurement of the intergalactic medium temperature around a quasar at z = 6 , 2010, 1001.3415.

[18]  V. Narayanan,et al.  A Survey of z > 5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at z > 6 , 2003, astro-ph/0301135.

[19]  Judd D. Bowman,et al.  The Sensitivity of First-Generation Epoch of Reionization Observatories and Their Potential for Differentiating Theoretical Power Spectra , 2005, astro-ph/0507357.

[20]  21-cm fluctuations from inhomogeneous X-ray heating before reionization , 2006, astro-ph/0607234.

[21]  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.

[22]  Sarod Yatawatta,et al.  Distributed Radio Interferometric Calibration , 2015, ArXiv.

[23]  N. Konidaris,et al.  LINE-EMITTING GALAXIES BEYOND A REDSHIFT OF 7: AN IMPROVED METHOD FOR ESTIMATING THE EVOLVING NEUTRALITY OF THE INTERGALACTIC MEDIUM , 2014, 1404.4632.

[24]  Abraham Loeb,et al.  21 cm cosmology in the 21st century , 2011, Reports on progress in physics. Physical Society.

[25]  Hao He,et al.  Spectral Analysis of Nonuniformly Sampled Data: A New Approach Versus the Periodogram , 2009, IEEE Transactions on Signal Processing.

[26]  A. Scaife,et al.  A broad-band flux scale for low-frequency radio telescopes , 2012, 1203.0977.

[27]  N. Yoshida,et al.  The Dark Ages of the Universe and hydrogen reionization , 2014, 1404.7146.

[28]  Christopher Hirata,et al.  A simulation-calibrated limit on the H i power spectrum from the GMRT Epoch of Reionization experiment , 2013, 1301.5906.

[29]  A. H. Patil,et al.  Polarization leakage in epoch of reionization windows – I. Low Frequency Array observations of the 3C196 field , 2015 .

[30]  Mohamed-Jalal Fadili,et al.  Morphological Component Analysis: An Adaptive Thresholding Strategy , 2007, IEEE Transactions on Image Processing.

[31]  Martin J. Rees,et al.  21 CENTIMETER TOMOGRAPHY OF THE INTERGALACTIC MEDIUM AT HIGH REDSHIFT , 1996 .

[32]  U. Sydney,et al.  Polarized foreground removal at low radio frequencies using rotation measure synthesis: uncovering the signature of hydrogen reionization , 2010, 1011.2321.

[33]  Judd D. Bowman,et al.  FOREGROUND CONTAMINATION IN INTERFEROMETRIC MEASUREMENTS OF THE REDSHIFTED 21 cm POWER SPECTRUM , 2008, 0807.3956.

[34]  J. Brinkmann,et al.  A Survey of z > 5.7 Quasars in the Sloan Digital Sky Survey. IV. Discovery of Seven Additional Quasars , 2004, astro-ph/0405138.

[35]  Hannes Jensen,et al.  Reionization and the Cosmic Dawn with the Square Kilometre Array , 2012, 1210.0197.

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

[37]  A. Loeb,et al.  A Method for Separating the Physics from the Astrophysics of High-Redshift 21 Centimeter Fluctuations , 2004, astro-ph/0409572.

[38]  Saleem Zaroubi,et al.  The effect of foreground mitigation strategy on EoR window recovery , 2014, 1408.4695.

[39]  A. H. Patil,et al.  Systematic biases in low-frequency radio interferometric data due to calibration: the LOFAR-EoR case , 2016, 1605.07619.

[40]  Alan E. E. Rogers,et al.  Science with the Murchison Widefield Array , 2012, Publications of the Astronomical Society of Australia.

[41]  A. H. Patil.  Constraining the epoch of reionization with the variance statistic , 2014, 2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS).

[42]  J. Fadili,et al.  SZ and CMB reconstruction using generalized morphological component analysis , 2007, 0712.0588.

[43]  J. Roerdink,et al.  A morphological algorithm for improving radio-frequency interference detection , 2012, 1201.3364.

[44]  J. Pritchard,et al.  Distinguishing models of reionization using future radio observations of 21-cm 1-point statistics , 2013, 1312.1342.

[45]  Rida T. Farouki,et al.  The Bernstein polynomial basis: A centennial retrospective , 2012, Comput. Aided Geom. Des..

[46]  N. Udaya Shankar,et al.  IMAGING THE EPOCH OF REIONIZATION: LIMITATIONS FROM FOREGROUND CONFUSION AND IMAGING ALGORITHMS , 2011, 1106.1297.

[47]  Saleem Zaroubi,et al.  Clustered Calibration: An Improvement to Radio Interferometric Direction Dependent Self-Calibration , 2013, ArXiv.

[48]  M. Rees,et al.  21 Centimeter Tomography of the Intergalactic Medium at High Redshift , 1996, astro-ph/9608010.

[49]  J.-L. Starck,et al.  Sparse component separation for accurate cosmic microwave background estimation , 2012, 1206.1773.

[50]  James S. Bolton,et al.  The observed ionization rate of the intergalactic medium and the ionizing emissivity at z≥ 5: evidence for a photon-starved and extended epoch of reionization , 2007 .

[51]  Edward J. Wollack,et al.  Three Year Wilkinson Microwave Anistropy Probe (WMAP) Observations: Polarization Analysis , 2006, astro-ph/0603450.

[52]  Miguel F. Morales,et al.  Toward Epoch of Reionization Measurements with Wide-Field Radio Observations , 2003 .

[53]  J. Starck,et al.  The scale of the problem: Recovering images of reionization with Generalized Morphological Component Analysis , 2012, 1209.4769.

[54]  M. Franx,et al.  UV LUMINOSITY FUNCTIONS AT REDSHIFTS z ∼ 4 TO z ∼ 10: 10,000 GALAXIES FROM HST LEGACY FIELDS , 2014, 1403.4295.

[55]  Barak A. Pearlmutter,et al.  Blind Source Separation by Sparse Decomposition in a Signal Dictionary , 2001, Neural Computation.

[56]  Sarod Yatawatta,et al.  Efficient computation of prolate spheroidal wave functions in radio astronomical source modeling , 2011, 2011 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT).

[57]  R. Sault,et al.  Understanding radio polarimetry. I. Mathematical foundations , 1996 .

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

[59]  J. Schaye,et al.  Initial deep LOFAR observations of epoch of reionization windows. I. The north celestial pole , 2013, 1301.1630.

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

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

[62]  R. Bouwens,et al.  z ∼ 7 GALAXIES IN THE HUDF: FIRST EPOCH WFC3/IR RESULTS , 2009, 0909.1806.

[63]  Edinburgh,et al.  COSMIC REIONIZATION AND EARLY STAR-FORMING GALAXIES: A JOINT ANALYSIS OF NEW CONSTRAINTS FROM PLANCK AND THE HUBBLE SPACE TELESCOPE , 2015, 1502.02024.

[64]  S. Kazemi,et al.  Probing ionospheric structures using the LOFAR radio telescope , 2016, 1606.04683.

[65]  Edward J. Wollack,et al.  NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: COSMOLOGICAL PARAMETER RESULTS , 2012, 1212.5226.

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

[67]  Daniel A. Mitchell,et al.  CHIPS: THE COSMOLOGICAL H i POWER SPECTRUM ESTIMATOR , 2016, 1601.02073.

[68]  Saleem Zaroubi,et al.  Non-parametric foreground subtraction for 21-cm epoch of reionization experiments , 2009 .

[69]  The effect of Galactic foreground subtraction on redshifted 21-cm observations of quasar H ii regions , 2008, 0805.0038.

[70]  J. Anderson,et al.  The LOFAR radio environment , 2012, 1210.0393.

[71]  M. Morales,et al.  Calibration requirements for detecting the 21 cm epoch of reionization power spectrum and implications for the SKA , 2016, 1603.00607.

[72]  Caltech,et al.  Detection of extended He II reionization in the temperature evolution of the intergalactic medium , 2010, 1008.2622.

[73]  J. Bolton,et al.  New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization , 2013, 1307.2259.

[74]  A. Loeb,et al.  Evolution of the 21 cm signal throughout cosmic history , 2008, 0802.2102.

[75]  Mark Lacy,et al.  The contribution of high-redshift galaxies to cosmic reionization: New results from deep WFC3 imaging of the Hubble Ultra Deep Field , 2009, 0909.2255.

[76]  M. Franx,et al.  DISCOVERY OF z ∼ 8 GALAXIES IN THE HUBBLE ULTRA DEEP FIELD FROM ULTRA-DEEP WFC3/IR OBSERVATIONS , 2009, 0909.1803.

[77]  Max Tegmark.  How to measure CMB power spectra without losing information , 1996, astro-ph/9611174.

[78]  Chih-Ling Tsai,et al.  Bias in nonlinear regression , 1986 .

[79]  T. Murphy,et al.  wsclean: an implementation of a fast, generic wide-field imager for radio astronomy , 2014, 1407.1943.

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

[81]  S. Zaroubi,et al.  Foregrounds for observations of the cosmological 21 cm line - II. Westerbork observations of the fields around 3C 196 and the North Celestial Pole , 2010, 1002.4177.