First limits on the 21 cm power spectrum during the Epoch of X-ray heating
We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly diff...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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2017
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| Online Access: | http://hdl.handle.net/1721.1/108231 https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 |
| _version_ | 1826217138661097472 |
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| author | Ewall-Wice, Aaron Michael Dillon, Joshua Shane Hewitt, Jacqueline N Neben, Abraham Richard Tegmark, Max Erik Feng, Lu Goeke, Robert F |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Ewall-Wice, Aaron Michael Dillon, Joshua Shane Hewitt, Jacqueline N Neben, Abraham Richard Tegmark, Max Erik Feng, Lu Goeke, Robert F |
| author_sort | Ewall-Wice, Aaron Michael |
| collection | MIT |
| description | We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1–3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k ≲ 0.5 h Mpc[superscript −1]. This represents the first upper limits on the 21 cm power spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window. |
| first_indexed | 2024-09-23T16:58:38Z |
| format | Article |
| id | mit-1721.1/108231 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:58:38Z |
| publishDate | 2017 |
| record_format | dspace |
| spelling | mit-1721.1/1082312022-09-29T22:49:26Z First limits on the 21 cm power spectrum during the Epoch of X-ray heating Ewall-Wice, Aaron Michael Dillon, Joshua Shane Hewitt, Jacqueline N Neben, Abraham Richard Tegmark, Max Erik Feng, Lu Goeke, Robert F Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Ewall-Wice, Aaron Michael Dillon, Joshua Shane Hewitt, Jacqueline N Neben, Abraham Richard Tegmark, Max Erik Feng, Lu Goeke, Robert F We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1–3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k ≲ 0.5 h Mpc[superscript −1]. This represents the first upper limits on the 21 cm power spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window. National Science Foundation (U.S.) (AST-0457585) National Science Foundation (U.S.) (AST-0821321) National Science Foundation (U.S.) (AST-1105835) National Science Foundation (U.S.) (AST-1410719) National Science Foundation (U.S.) (AST-1410484) National Science Foundation (U.S.) (AST-1411622) National Science Foundation (U.S.) (AST-1440343) National Science Foundation (U.S.) (1122374) National Science Foundation (U.S.) (AST-0457585) National Science Foundation (U.S.) (PHY-0835713) National Science Foundation (U.S.) (CAREER-0847753) National Science Foundation (U.S.) (AST-0908884) United States. Air Force Office of Scientific Research (FA9550-0510247) 2017-04-18T20:01:04Z 2017-04-18T20:01:04Z 2017-04-18 Article http://purl.org/eprint/type/JournalArticle 0035-8711 1365-2966 http://hdl.handle.net/1721.1/108231 Ewall-Wice, A., Joshua S. Dillon, J. N. Hewitt, A. Loeb, A. Mesinger, A. R. Neben, A. R. Offringa, et al. “First Limits on the 21 Cm Power Spectrum During the Epoch of X-Ray Heating.” Monthly Notices of the Royal Astronomical Society 460, no. 4 (May 19, 2016): 4320–4347. © 2016 The Authors https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 en_US http://dx.doi.org/10.1093/mnras/stw1022 Monthly Notices of the Royal Astronomical Society Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf arXiv |
| spellingShingle | Ewall-Wice, Aaron Michael Dillon, Joshua Shane Hewitt, Jacqueline N Neben, Abraham Richard Tegmark, Max Erik Feng, Lu Goeke, Robert F First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title | First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title_full | First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title_fullStr | First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title_full_unstemmed | First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title_short | First limits on the 21 cm power spectrum during the Epoch of X-ray heating |
| title_sort | first limits on the 21 cm power spectrum during the epoch of x ray heating |
| url | http://hdl.handle.net/1721.1/108231 https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 |
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