TY - JOUR
T1 - New EoR power spectrum limits from MWA Phase II using the delay spectrum method and novel systematic rejection
AU - Kolopanis, Matthew
AU - Pober, Jonathan C.
AU - Jacobs, Daniel C.
AU - McGraw, Samantha
N1 - Funding Information:
This scientific work makes use of the Murchison Radio-astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site. Support for the operation of the MWA is provided by the Australian Government (NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. We acknowledge the Pawsey Supercomputing Centre, which is supported by the Western Australian Government and Australian Government. The MWA Phase II upgrade project was supported by Australian Research Council LIEF grant LE160100031 and the Dunlap Institute for Astronomy and Astrophysics, University of Toronto. This research was conducted using computation resources and services at the Center for Computation and Visualization, Brown University.
Funding Information:
Support for MK and DCJ has been provided by the National Science Foundation under grant numbers 2144995 and 2104350. Support for JCP has been provided by the National Science Foundation under grant number 2106510. SM received support from Brown University’s Karen T. Romer Undergraduate Teaching and Research Awards (UTRA) program and the NASA Rhode Island Space Grant. The authors would also like to thank Miguel Morales for helpful feedback and discussion.
Funding Information:
Support for MK and DCJ has been provided by the National Science Foundation under grant numbers 2144995 and 2104350. Support for JCP has been provided by the National Science Foundation under grant number 2106510. SM received support from Brown University’s Karen T. Romer Undergraduate Teaching and Research Awards (UTRA) program and the NASA Rhode Island Space Grant. The authors would also like to thank Miguel Morales for helpful feedback and discussion. This scientific work makes use of the Murchison Radio-astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site. Support for the operation of the MWA is provided by the Aus- tralian Go v ernment (NCRIS), under a contract to Curtin Univer- sity administered by Astronomy Australia Limited. We acknowl- edge the P a wse y Supercomputing Centre, which is supported by the Western Australian Go v ernment and Australian Go v ernment. The MWA Phase II upgrade project was supported by Australian Research Council LIEF grant LE160100031 and the Dunlap Istitute for Astronomy and Astrophysics, University of Toronto. This research was conducted using computation resources and services at the Center for Computation and Visualization, Brown University.
Publisher Copyright:
© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2023/6/1
Y1 - 2023/6/1
N2 - We present an analysis of Epoch of Reionization (EoR) data from Phase II of the Murchison Widefield Array using the simpleds delay spectrum pipeline. Prior work analysed the same observations using the fhd/ϵppsilon 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 $|k| lt 1 , h_100, rm Mpc^-1$ with a lowest measurement of Δ2(k) ≤ 4.58 × 103 mK2 at $k = 0.190, h_100, rm Mpc^-1$ 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 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 modelling systematics as positive-definite contributions to the power spectrum and in 'conservatively' interpreting all measurements as upper limits.
AB - We present an analysis of Epoch of Reionization (EoR) data from Phase II of the Murchison Widefield Array using the simpleds delay spectrum pipeline. Prior work analysed the same observations using the fhd/ϵppsilon 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 $|k| lt 1 , h_100, rm Mpc^-1$ with a lowest measurement of Δ2(k) ≤ 4.58 × 103 mK2 at $k = 0.190, h_100, rm Mpc^-1$ 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 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 modelling systematics as positive-definite contributions to the power spectrum and in 'conservatively' interpreting all measurements as upper limits.
KW - dark ages, reionization, first stars
KW - methods: data analysis
KW - techniques: interferometric
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U2 - 10.1093/mnras/stad845
DO - 10.1093/mnras/stad845
M3 - Article
AN - SCOPUS:85154057301
SN - 0035-8711
VL - 521
SP - 5120
EP - 5138
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -