New EoR Power Spectrum Limits From MWA Phase II Using the Delay Spectrum Method and Novel Systematic Rejection

Abstract

We present an analysis of Epoch of Reionization data from Phase II of the Murchison Widefield Array using the \texttt{simpleDS} delay spectrum pipeline. Prior work analyzed the same observations using the FHD/$\epsilon$ppsilon imaging pipeline, and so the present analysis represents the first time that both principal types of 21 cm cosmology power spectrum estimation approaches have been applied to the same data set. Our limits on the 21 cm power spectrum amplitude span a range in $k$ space of $|k|<1h_{100}{\mathrm{Mpc}}^{-1}$ with a lowest measurement of ${\Delta }^2(k)\le$ $4.58\times 10^3$ mK${}^2$ at $k=0.190h_{100}{\mathrm{Mpc}}^{-1}$ and $z=7.14$. In order to achieve these limits, we need to mitigate a previously unidentified common mode systematic in the data set. If not accounted for, this systematic introduces an overall \emph{negative} bias that can make foreground contaminated measurements appear as stringent, noise-limited constraints on the 21 cm signal amplitude. The identification of this systematic highlights the risk in modeling systematics as positive-definite contributions to the power spectrum and in ``conservatively'' interpreting all measurements as upper limits.

19 pages, 12 figures, Accepted by MNRAS; Updated to match published version

References in corpus (20)

• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• Post-correlation radio frequency interference classification methods
• The Epoch of Reionization Window: I. Mathematical Formalism
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
• HERA Phase I Limits on the Cosmic 21-cm Signal: Constraints on Astrophysics and Cosmology During the Epoch of Reionization
• Spectral Index of the Diffuse Radio Background Measured From 100 to 200 MHz
• Fast Holographic Deconvolution: a new technique for precision radio interferometry
• First Season MWA Phase II EoR Power Spectrum Results at Redshift 7
• MITEoR: A Scalable Interferometer for Precision 21 cm Cosmology
• Mitigating Internal Instrument Coupling for 21 cm Cosmology I: Temporal and Spectral Modeling in Simulations
• Mitigating Internal Instrument Coupling II: A Method Demonstration with the Hydrogen Epoch of Reionization Array
• Understanding Instrumental Stokes Leakage in Murchison Widefield Array Polarimetry
• The impact of interference excision on 21-cm Epoch of Reionization power spectrum analyses
• The FHD/$\mathbf{\epsilon }$ppsilon Epoch of Reionization Power Spectrum Pipeline
• A Digital-Receiver for the Murchison Widefield Array
• Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
• A Map of Diffuse Radio Emission at 182 MHz to Enhance Epoch of Reionization Observations in the Southern Hemisphere
• Methods of Error Estimation for Delay Power Spectra in $21\text{cm}$ Cosmology

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• A direct detection of neutral hydrogen intensity mapping on Mpc scales at $z\approx 0.32$ and $z\approx 0.44$
• The Tracking Tapered Gridded Estimator for the 21-cm power spectrum from MWA drift scan observations I: Validation and preliminary results
• A fast method of reionization parameter space exploration using GPR trained SCRIPT
• Spectral modelling of Cygnus A between 110 and 250 MHz. Impact on the LOFAR 21-cm signal power spectrum
• First upper limits on the 21-cm signal power spectrum of neutral hydrogen at $z=9.16$ from the LOFAR 3C196 field
• A Differentiable, End-to-End Forward Model for 21 cm Cosmology: Estimating the Foreground, Instrument, and Signal Joint Posterior
• The Statistics of Negative Power Spectrum Systematics in some 21 cm Analyses
• Strategy for mitigation of systematics for EoR experiments with the Murchison Widefield Array
• Ionospheric effect on the synthetic Epoch of Reionization observations with the SKA1-Low
• Primary Beam Chromaticity in HIRAX: I. Characterization from Simulations and Power Spectrum Implications
• The signature of galaxy formation models in the power spectrum of the hydrogen 21cm line during reionization
• Interpreting the HI 21-cm cosmology maps through Largest Cluster Statistics. Part II. Impact of the realistic foreground and instrumental noise on synthetic SKA1-Low observations
• Simulation based inference of the ionization history from the 2D 21 cm power spectrum
• Mitigating gain calibration errors from EoR observations with SKA1-Low AA*