Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data

Joshua S. Dillon, Adrian Liu, Christopher L. Williams, Jacqueline N. Hewitt, Max Tegmark, Edward H. Morgan, Alan M. Levine, Miguel F. Morales, Steven J. Tingay, Gianni Bernardi, Judd Bowman, Frank H. Briggs, Roger C. Cappallo, David Emrich, Daniel A. Mitchell, Divya Oberoi, Thiagaraj Prabu, Randall Wayth, Rachel L. Webster

Research output: Contribution to journalArticle

107 Scopus citations

Abstract

We present techniques for bridging the gap between idealized inverse covariance weighted quadratic estimation of 21 cm power spectra and the real-world challenges presented universally by interferometric observation. By carefully evaluating various estimators and adapting our techniques for large but incomplete data sets, we develop a robust power spectrum estimation framework that preserves the so-called Epoch of Reionization (EoR) window and keeps track of estimator errors and covariances. We apply our method to observations from the 32-tile prototype of the Murchinson Widefield Array to demonstrate the importance of a judicious analysis technique. Lastly, we apply our method to investigate the dependence of the clean EoR window on frequency - especially the frequency dependence of the so-called "wedge feature - and establish upper limits on the power spectrum from z=6.2 to z=11.7. Our lowest limit is Δ(k)<0.3 Kelvin at 95% confidence at a comoving scale k=0.046 Mpc-1 and z=9.5.

Original languageEnglish (US)
Article number023002
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume89
Issue number2
DOIs
StatePublished - Jan 15 2014

    Fingerprint

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

Cite this

Dillon, J. S., Liu, A., Williams, C. L., Hewitt, J. N., Tegmark, M., Morgan, E. H., Levine, A. M., Morales, M. F., Tingay, S. J., Bernardi, G., Bowman, J., Briggs, F. H., Cappallo, R. C., Emrich, D., Mitchell, D. A., Oberoi, D., Prabu, T., Wayth, R., & Webster, R. L. (2014). Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data. Physical Review D - Particles, Fields, Gravitation and Cosmology, 89(2), [023002]. https://doi.org/10.1103/PhysRevD.89.023002