A new MWA limit on the 21 cm power spectrum at redshifts ∼13-17

A new MWA limit on the 21 cm power spectrum at redshifts ∼13-17

Observations in the lowest Murchison Widefield Array (MWA) band between 75 and 100 MHz have the potential to constrain the distribution of neutral hydrogen in the intergalactic medium at redshift ∼13-17. Using 15 h of MWA data, we analyse systematics in this band such as radio-frequency interference...

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Bibliographic Details
Main Authors: Yoshiura, S., Pindor, B., Line, J.L.B., Barry, Nichole, Trott, Cathryn, Beardsley, A., Bowman, J., Byrne, R., Chokshi, A., Hazelton, B.J., Hasegawa, K., Howard, E., Greig, B., Jacobs, D., Jordan, Chris, Joseph, R., Kolopanis, M., Lynch, Christene, McKinley, Ben, Mitchell, D.A., Morales, M.F., Murray, Steven, Pober, J.C., Rahimi, M., Takahashi, K., Tingay, Steven, Wayth, Randall, Webster, R.L., Wilensky, M., Wyithe, J.S.B., Zhang, Z., Zheng, Q.
Format: Journal Article
Language:English
Published: OXFORD UNIV PRESS 2021
Subjects:
Science & Technology
Physical Sciences
Astronomy & Astrophysics
methods: data analysis
dark ages, reionization, first stars
MURCHISON WIDEFIELD ARRAY
COSMIC DAWN
FUNDAMENTAL LIMITATIONS
NEUTRAL HYDROGEN
LIGHT-CONE
EPOCH
REIONIZATION
CALIBRATION
SIGNAL
LOFAR
astro-ph.CO
Online Access:http://dx.doi.org/10.1093/mnras/stab1560
http://hdl.handle.net/20.500.11937/91573
Description
Summary:Observations in the lowest Murchison Widefield Array (MWA) band between 75 and 100 MHz have the potential to constrain the distribution of neutral hydrogen in the intergalactic medium at redshift ∼13-17. Using 15 h of MWA data, we analyse systematics in this band such as radio-frequency interference (RFI), ionospheric and wide field effects. By updating the position of point sources, we mitigate the direction-independent calibration error due to ionospheric offsets. Our calibration strategy is optimized for the lowest frequency bands by reducing the number of direction-dependent calibrators and taking into account radio sources within a wider field of view. We remove data polluted by systematics based on the RFI occupancy and ionospheric conditions, finally selecting 5.5 h of the cleanest data. Using these data, we obtain 2σ upper limits on the 21 cm power spectrum in the range of 0.1 h Mpc-1 ≲ k ≲ 1 h Mpc-1 and at z = 14.2, 15.2, and 16.5, with the lowest limit being 6.3 × 106 mK2 at k=0.14 h Mpc-1 and at z = 15.2 with a possibility of a few per cent of signal loss due to direction-independent calibration.

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