FOREGROUND CONTAMINATION IN INTERFEROMETRIC MEASUREMENTS OF THE REDSHIFTED 21 cm POWER SPECTRUM

By Judd D. Bowman, Miguel F. Morales, Jacqueline N. Hewitt. 2008

141 citations recorded by the source corpus.

Subtraction of astrophysical foreground contamination from “dirty” sky maps produced by simulated measurements of the Murchison Widefield Array (MWA) has been performed by fitting a third-order polynomial along the spectral dimension of each pixel in the data cubes. The simulations are the first to include the unavoidable instrumental effects of the frequency-dependent primary antenna beams and synthesized array beams. They recover the one-dimensional spherically binned input redshifted 21 cm power spectrum within ∼1% over the scales probed most sensitively by the MWA (0.01 ≲ k ≲ 1 Mpc−1) and demonstrate that realistic instrumental effects will not mask the epoch of reionization signal. We find that the weighting function used to produce the dirty sky maps from the gridded visibility measurements is important to the success of the technique. Uniform weighting of the visibility measurements produces the best results, whereas natural weighting significantly worsens the foreground subtraction by coupling structure in the density of the visibility measurements to spectral structure in the dirty sky map data cube. The extremely dense uv-coverage of the MWA was found to be advantageous for this technique and produced very good results on scales corresponding to |u| ≲ 500λ in the uv-plane without any selective editing of the uv-coverage.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/cbf1fe55c7943e05e21ec52dea652dd797712d54

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Citations in the corpus

Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR (2017, background): “Using the former one can assess remaining systematics due to e.g. foreground residuals, side-lobe noise and frequency-coherent effects (e.g. Bowman et al. 2009; Vedantham et al. 2012).”
The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at z≈ 8.6 (2010, background): “…foregrounds adequately is essential for detecting the EoR signal (see, e.g., Wang et al. 2006) and much work has been done on simulating foregrounds (e.g. Bowman et al. 2009; Jelić et al. 2010) and designing removal strategies (Morales et al. 2006; Harker et al. 2009; Liu et al. 2009, and others).”
BRIGHT SOURCE SUBTRACTION REQUIREMENTS FOR REDSHIFTED 21 cm MEASUREMENTS (2010, methodology): “Hence, we have assumed that the ﬁnal power spectrum from the real data will be generated by dividing the observation into different epochs of equal duration and then cross-correlating the data cubes from the two epochs (Bowman et al. 2009).”
FOUR FUNDAMENTAL FOREGROUND POWER SPECTRUM SHAPES FOR 21 cm COSMOLOGY OBSERVATIONS (2012, background): “Accurately determining the foregrounds is particularly difficult in the confusion limit, and Liu et al. (2009) and Bowman et al. (2009) have done excellent work on improving the accuracy of the foreground models in the confusion limit.”
A PER-BASELINE, DELAY-SPECTRUM TECHNIQUE FOR ACCESSING THE 21 cm COSMIC REIONIZATION SIGNATURE (2012, methodology): “…presented here for the delay-spectrum technique differs substantially for other schemes that have been recently presented in the literature (e.g. Bowman et al. 2009; Vedantham et al. 2012) in that within an 8-MHz sub-band, every frequency channel has been formed from the same weighted sum of…”
PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM AT z = 8.4 (2015, methodology): “Morales et al. 2006; Bowman et al. 2009a).”
WHAT NEXT-GENERATION 21 cm POWER SPECTRUM MEASUREMENTS CAN TEACH US ABOUT THE EPOCH OF REIONIZATION (2013, background): “A large literature of work has gone into studying the removal of foreground emission from 21 cm data (e.g. Morales et al. 2006, Bowman et al. 2009, Liu et al. 2009, Liu & Tegmark 2011, Chapman et al. 2012, Dillon et al. 2013a, Chapman et al. 2013).”
A SENSITIVITY AND ARRAY-CONFIGURATION STUDY FOR MEASURING THE POWER SPECTRUM OF 21 cm EMISSION FROM REIONIZATION (2011, background): “Removing foregrounds that are orders of magnitude brighter than the signal and obtaining the requisite sensitivity are the primary concerns that influence the design of all 21cm instruments (Parsons et al. 2010; Bowman et al. 2009; Paciga et al. 2010).”
Science with the Murchison Widefield Array (2012, methodology): “Many classes of errors and residuals re- maining in the maps after the foreground cleaning stages described above can be modeled given sufficient knowledge of the instrumental response (Morales et al. 2006; Bowman et al. 2009; Datta et al. 2010; Morales et al. 2012).”
THE IMPACT OF POINT-SOURCE SUBTRACTION RESIDUALS ON 21 cm EPOCH OF REIONIZATION ESTIMATION (2012, methodology): “The wedge-shaped feature extending from small k⊥–small k‖ to large k⊥–large k‖ was first reported by Datta et al. (2010) (after initial indications from Bowman et al. 2009, and has been further discussed by Vedantham et al. 2012 and Morales et al. 2012), and is the power footprint of the…”
FIRST SEASON MWA EOR POWER SPECTRUM RESULTS AT REDSHIFT 7 (2016, background): “Central to most analysis strategies is the concept of an “EoR window” – the region of Fourier space where spectrally smooth foregrounds have been isolated from the isotropic (spherically symmetric in Fourier space) cosmological signal (Morales et al. 2006; Bowman et al. 2009).”
OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER (2013, background): “…Cavendish Lab., Cambridge, UK 11 http://www.lofar.org/ 12 http://www.mwatelescope.org/ 13 http://eor.berkeley.edu/ schemes to remove or isolate foregrounds from 21cm data (e.g. Morales et al. 2006, Bowman et al. 2009, Liu et al. 2009, Liu & Tegmark 2011, Parsons et al. 2012b, Dillon et al. 2012).”