Extracting the 21 cm EoR signal using MWA drift scan data

Abstract

The detection of redshifted hyperfine line of neutral hydrogen (HI) is the most promising probe of the Epoch of Reionization (EoR). We report an analysis of 55 hours of Murchison Widefield Array (MWA) Phase II drift scan EoR data. The data correspond to a central frequency ${\nu }_0=154.24\mathrm{MHz}$ ($z\simeq 8.2$ for the redshifted HI hyperfine line) and bandwidth $B=10.24\mathrm{MHz}$. As one expects greater system stability in a drift scan, we test the system stability by comparing the extracted power spectra from data with noise simulations and show that the power spectra for the cleanest data behave as thermal noise. We compute the HI power spectrum as a function of time in one and two dimensions. The best upper limit on the one-dimensional power spectrum are: ${\Delta }^2(k)\simeq (1000\mathrm{mK}{)}^2$ at $k\simeq 0.2$$h{\mathrm{Mpc}}^{-1}$ and at $k\simeq 1$$h{\mathrm{Mpc}}^{-1}$. The cleanest modes, which might be the most suited for obtaining the optimal signal-to-noise, correspond to $k\gtrsim 1$$h{\mathrm{Mpc}}^{-1}$. We also study the time-dependence of the foreground-dominated modes in a drift scan and compare with the expected behaviour.

arXiv comment11 pages, 8 figures. Accepted for publication in MNRAS

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• A new MWA limit on the 21 cm Power Spectrum at Redshifts $\sim$ 13 $-$ 17
• Studying Cosmic Dawn using redshifted HI 21-cm signal: A brief review
• Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• Implications of the $z>5$ Lyman-$\alpha$ forest for the 21-cm power spectrum from the epoch of reionization
• CII and HI 21-cm line intensity mapping from the EoR: Impact of the light-cone effect on auto and cross-power spectra
• SKA-Low Intensity Mapping Pathfinder Updates: Deeper 21 cm Power Spectrum Limits from Improved Analysis Frameworks
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• Particle production during inflation: constraints expected from redshifted 21 cm observations from the epoch of reionization