FIRST SEASON MWA EOR POWER SPECTRUM RESULTS AT REDSHIFT 7

The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch of Reionization (EoR) data and now faces the challenge of overcoming foreground and systematic contamination to reduce the data to a cosmological measurement. We introduce several novel analysis techniques such as cable reflection calibration, hyper-resolution gridding kernels, diffuse foreground model subtraction, and quality control methods. Each change to the analysis pipeline is tested against a two dimensional power spectrum figure of merit to demonstrate improvement. We incorporate the new techniques into a deep integration of 32 hours of MWA data. This data set is used to place a systematic-limited upper limit on the cosmological power spectrum of $\Delta^2 \leq 2.7 \times 10^4$ mK$^2$ at $k=0.27$ h~Mpc$^{-1}$ and $z=7.1$, consistent with other published limits, and a modest improvement (factor of 1.4) over previous MWA results. From this deep analysis we have identified a list of improvements to be made to our EoR data analysis strategies. These improvements will be implemented in the future and detailed in upcoming publications.

A. R. Whitney | S. J. Tingay | G. Bernardi | D. A. Mitchell | S. M. Ord | L. J. Greenhill | B. Pindor | R. B. Wayth | M. Johnston-Hollitt | N. Udaya Shankar | N. Hurley-Walker | J. C. Pober | M. Tegmark | C. M. Trott | Nithyanandan Thyagarajan | Judd D. Bowman | A. E. E. Rogers | P. Carroll | E. Lenc | K. S. Srivani | A. R. Offringa | P. Procopio | J. C. Kasper | B. J. Hazelton | M. F. Morales | A. P. Beardsley | F. Briggs | D. Emrich | A. Ewall-Wice | J. N. Hewitt | J. Line | Daniel C. Jacobs | E. Morgan | A. Roshi | B. M. Gaensler | R. L. Webster | B. McKinley | D. L. Kaplan | J. S. B. Wyithe | Joshua S. Dillon | T. Prabu | Max Tegmark | E. Lenc | D. Kaplan | J. Hewitt | B. Pindor | R. Webster | S. Tingay | M. Morales | C. Trott | E. Morgan | A. D. Oliveira-Costa | A. Loeb | D. Oberoi | P. Carroll | A. Rogers | B. Corey | R. Cappallo | A. Whitney | I. Sullivan | R. Wayth | P. Procopio | J. Kasper | A. Offringa | J. Pober | A. Beardsley | G. Bernardi | J. Bowman | J. Dillon | A. Ewall-Wice | B. Hazelton | D. Jacobs | A. Neben | N. Thyagarajan | J. Wyithe | R. Goeke | R. Subrahmanyan | M. Johnston-Hollitt | F. Briggs | B. Gaensler | D. Mitchell | L. Greenhill | S. Ord | C. Lonsdale | S. McWhirter | M. Lynch | M. Waterson | A. Williams | S. Sethi | D. Emrich | N. Hurley-Walker | N. Shankar | K. Srivani | B. McKinley | C. Wu | E. Kratzenberg | T. Prabu | A. Roshi | C. Williams | L. Feng | J. Riding | J. Line | M. Rahimi | N. Barry | A. Williams | M. Busch | N. Barry | R. J. Cappallo | B. E. Corey | A. de Oliveira-Costa | L. Feng | R. Goeke | E. Kratzenberg | A. Loeb | C. J. Lonsdale | M. J. Lynch | S. R. McWhirter | A. R. Neben | D. Oberoi | J. Riding | R. Subrahmanyan | I. S. Sullivan | M. Waterson | C. L. Williams | C. Wu | H. S. Kim | S. Paul | Shiv K. Sethi | M. Rahimi | M. P. Busch | S. Paul | H. Kim

[1]  Max Tegmark,et al.  A high reliability survey of discrete Epoch of Reionization foreground sources in the MWA EoR0 field , 2016, 1607.03861.

[2]  J. Scargle.  Studies in astronomical time series analysis. II - Statistical aspects of spectral analysis of unevenly spaced data , 1982 .

[3]  A. R. Whitney,et al.  A new layout optimization technique for interferometric arrays, applied to the MWA , 2012, 1203.1293.

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

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

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

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

[8]  Miguel F. Morales,et al.  Software holography: interferometric data analysis for the challenges of next generation observatories , 2008, 0810.5107.

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

[10]  E. Lenc,et al.  GLEAM: The GaLactic and Extragalactic All-Sky MWA Survey , 2015, Publications of the Astronomical Society of Australia.

[11]  J. Pober,et al.  Constraints on the temperature of the intergalactic medium at z = 8.4 with 21-cm observations , 2015, 1509.02158.

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

[13]  Lars Hernquist,et al.  PROBING REIONIZATION WITH THE 21 CM GALAXY CROSS-POWER SPECTRUM , 2008, 0806.1055.

[14]  Hannes Jensen,et al.  Predictions for the 21 cm-galaxy cross-power spectrum observable with LOFAR and Subaru , 2015, 1509.03464.

[15]  Marco Piras,et al.  Antenna Pattern Verification System Based on a Micro Unmanned Aerial Vehicle (UAV) , 2014, IEEE Antennas and Wireless Propagation Letters.

[16]  Michael Biehl,et al.  Post‐correlation radio frequency interference classification methods , 2010, 1002.1957.

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

[18]  Cathryn M. Trott,et al.  Epoch of reionization window. I. Mathematical formalism , 2014, 1404.2596.

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

[20]  A. R. Whitney,et al.  THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS , 2016, 1601.06177.

[21]  M. Morales,et al.  THE FUNDAMENTAL MULTI-BASELINE MODE-MIXING FOREGROUND IN 21 cm EPOCH OF REIONIZATION OBSERVATIONS , 2013, 1301.3126.

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

[23]  Mark Waterson,et al.  A digital-receiver for the MurchisonWidefield Array , 2015, 1502.05015.

[24]  University College London,et al.  Polarization leakage in epoch of reionization windows – II. Primary beam model and direction-dependent calibration , 2016, 1604.04534.

[25]  A. R. Whitney,et al.  THE MURCHISON WIDEFIELD ARRAY 21 cm POWER SPECTRUM ANALYSIS METHODOLOGY , 2016, 1605.06978.

[26]  Christopher L. Williams,et al.  GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey - I. A low-frequency extragalactic catalogue , 2016, 1610.08318.

[27]  Jason Manley,et al.  OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER , 2013, 1301.7099.

[28]  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.

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

[30]  C. Breuck,et al.  A sample of 669 ultra steep spectrum radio sources to find high redshift radio galaxies , 2000, astro-ph/0002297.

[31]  M. I. Large,et al.  The Molonglo Reference Catalogue of radio sources. , 1981 .

[32]  S. J. Tingay,et al.  The Low-Frequency Environment of the Murchison Widefield Array: Radio-Frequency Interference Analysis and Mitigation , 2015, Publications of the Astronomical Society of Australia.

[33]  W. A. Coles,et al.  Interferometric Imaging with the 32 Element Murchison Wide-Field Array , 2010, 1010.1733.

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

[35]  Asantha Cooray,et al.  PROSPECTS FOR DETECTING C II EMISSION DURING THE EPOCH OF REIONIZATION , 2014, 1410.4808.

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

[37]  Matthew Malloy,et al.  IDENTIFYING IONIZED REGIONS IN NOISY REDSHIFTED 21 cm DATA SETS , 2012, 1212.2656.

[38]  A. R. Whitney,et al.  LOW-FREQUENCY OBSERVATIONS OF LINEARLY POLARIZED STRUCTURES IN THE INTERSTELLAR MEDIUM NEAR THE SOUTH GALACTIC POLE , 2016, 1607.05779.

[39]  A. A. Deshpande,et al.  Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data , 2015, 1506.01026.

[40]  J. Curran,et al.  SUMSS: a wide-field radio imaging survey of the southern sky – II. The source catalogue , 2003, astro-ph/0303188.

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

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

[43]  C. A. Oxborrow,et al.  Planck intermediate results - XLVII. Planck constraints on reionization history , 2016, 1605.03507.

[44]  Nipanjana Patra,et al.  SARAS: a precision system for measurement of the cosmic radio background and signatures from the epoch of reionization , 2012, 1211.3800.

[45]  S. J. Tingay,et al.  Parametrizing Epoch of Reionization foregrounds: a deep survey of low-frequency point-source spectra with the Murchison Widefield Array , 2016, 1602.02247.

[46]  Roger Cappallo,et al.  The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14 110 Compact Radio Sources over 6 100 Square Degrees , 2014, Publications of the Astronomical Society of Australia.

[47]  D. R. DeBoer,et al.  Hydrogen Epoch of Reionization Array (HERA) , 2016, 1606.07473.

[48]  Judd D. Bowman,et al.  IMPROVING FOREGROUND SUBTRACTION IN STATISTICAL OBSERVATIONS OF 21 cm EMISSION FROM THE EPOCH OF REIONIZATION , 2006 .

[49]  O. Lahav,et al.  A CENSUS OF STAR-FORMING GALAXIES IN THE Z ∼ 9–10 UNIVERSE BASED ON HST+SPITZER OBSERVATIONS OVER 19 CLASH CLUSTERS: THREE CANDIDATE Z ∼ 9–10 GALAXIES AND IMPROVED CONSTRAINTS ON THE STAR FORMATION RATE DENSITY AT Z ∼ 9.2 , 2012, 1211.2230.

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

[51]  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.

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

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

[54]  Cathryn M. Trott,et al.  Epoch of reionization window. II. Statistical methods for foreground wedge reduction , 2014, 1404.4372.

[55]  Roger J. Cappallo,et al.  Real-Time Calibration of the Murchison Widefield Array , 2008, IEEE Journal of Selected Topics in Signal Processing.

[56]  Max Tegmark,et al.  Mapmaking for precision 21 cm cosmology , 2014, Physical Review D.

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

[58]  A. A. Deshpande,et al.  FAST HOLOGRAPHIC DECONVOLUTION: A NEW TECHNIQUE FOR PRECISION RADIO INTERFEROMETRY , 2012, 1209.1653.

[59]  I. McGreer,et al.  Model-independent evidence in favour of an end to reionization by z ≈ 6 , 2014, 1411.5375.

[60]  Stefan J. Wijnholds,et al.  Fast gain calibration in radio astronomy using alternating direction implicit methods: Analysis and applications , 2014, 1410.2101.

[61]  Max Tegmark,et al.  FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA , 2015, 1502.07596.

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

[63]  C. Trott.  Comparison of Observing Modes for Statistical Estimation of the 21 cm Signal from the Epoch of Reionisation , 2014, Publications of the Astronomical Society of Australia.

[64]  David F. Moore,et al.  New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7 , 2013, 1304.4991.

[65]  B. Mobasher,et al.  JD 12: The First Galaxies - Theoretical Predictions and Observational Clues , 2009, Proceedings of the International Astronomical Union.

[66]  O. López-Cruz,et al.  PROBING THE DARK AGES AT z ∼ 20: THE SCI-HI 21 cm ALL-SKY SPECTRUM EXPERIMENT , 2013, 1311.0014.

[67]  Max Tegmark,et al.  CONFIRMATION OF WIDE-FIELD SIGNATURES IN REDSHIFTED 21 cm POWER SPECTRA , 2015, 1506.06150.

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

[69]  Rachel L. Webster,et al.  Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data , 2013, 1304.4229.

[70]  A. Loeb,et al.  The First Galaxies in the Universe , 2013 .

[71]  Alexander S. Szalay,et al.  TO APPEAR IN THE ASTROPHYSICAL JOURNAL Preprint typeset using LATEX style emulateapj v. 10/09/06 PROBABILISTIC CROSS-IDENTIFICATION OF ASTRONOMICAL SOURCES , 2008 .

[72]  G. W. Pratt,et al.  Planck 2015 results - XI. CMB power spectra, likelihoods, and robustness of parameters , 2015, 1507.02704.

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

[74]  C. A. Oxborrow,et al.  Planck2015 results , 2015, Astronomy & Astrophysics.

[75]  Bertrand Mennesson,et al.  Cosmology with the SPHEREX All-Sky Spectral Survey , 2014, 1412.4872.

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

[77]  D. DeBoer,et al.  EFFECTS OF ANTENNA BEAM CHROMATICITY ON REDSHIFTED 21 cm POWER SPECTRUM AND IMPLICATIONS FOR HYDROGEN EPOCH OF REIONIZATION ARRAY , 2016, 1603.08958.

[78]  J. Usón,et al.  Correcting direction-dependent gains in the deconvolution of radio interferometric images , 2008, 0805.0834.

[79]  E. Lenc,et al.  Understanding instrumental Stokes leakage in Murchison Widefield Array polarimetry , 2014, 1412.4466.

[80]  Christopher L. Williams,et al.  A STUDY OF FUNDAMENTAL LIMITATIONS TO STATISTICAL DETECTION OF REDSHIFTED H i FROM THE EPOCH OF REIONIZATION , 2013, 1308.0565.

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

[82]  David R. DeBoer,et al.  PAPER-64 CONSTRAINTS ON REIONIZATION. II. THE TEMPERATURE OF THE z = 8.4 INTERGALACTIC MEDIUM , 2015, 1503.00045.

[83]  M. Morales,et al.  ADDING CONTEXT TO JAMES WEBB SPACE TELESCOPE SURVEYS WITH CURRENT AND FUTURE 21 cm RADIO OBSERVATIONS , 2014, 1410.5427.

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

[85]  R. Ekers,et al.  BIGHORNS - Broadband Instrument for Global HydrOgen ReioNisation Signal , 2015, Publications of the Astronomical Society of Australia.

[86]  H. Rix,et al.  The James Webb Space Telescope , 2006, astro-ph/0606175.

[87]  Max Tegmark,et al.  First limits on the 21 cm power spectrum during the Epoch of X-ray heating , 2016, Monthly Notices of the Royal Astronomical Society.

[88]  E. Greisen,et al.  The NRAO VLA Sky Survey , 1996 .

[89]  Bryna Hazelton,et al.  FOUR FUNDAMENTAL FOREGROUND POWER SPECTRUM SHAPES FOR 21 cm COSMOLOGY OBSERVATIONS , 2012, 1202.3830.

[90]  Edward J. Wollack,et al.  NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: FINAL MAPS AND RESULTS , 2012, 1212.5225.

[91]  Robert H. Becker,et al.  Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ∼ 6 Quasars. II. A Sample of 19 Quasars , 2005, astro-ph/0512082.

[92]  S. J. Tingay,et al.  Measuring phased‐array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites , 2015, 1505.07114.

[93]  David R. DeBoer,et al.  MULTIREDSHIFT LIMITS ON THE 21 cm POWER SPECTRUM FROM PAPER , 2014, 1408.3389.