Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical SurveysCitation formats

  • Authors:
  • Steven Cunnington
  • Laura Wolz
  • Alkistis Pourtsidou
  • David Bacon

Standard

Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys. / Cunnington, Steven; Wolz, Laura; Pourtsidou, Alkistis; Bacon, David.

In: Monthly Notices of the Royal Astronomical Society, 11.07.2019.

Research output: Contribution to journalArticlepeer-review

Harvard

Cunnington, S, Wolz, L, Pourtsidou, A & Bacon, D 2019, 'Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys', Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/stz1916

APA

Cunnington, S., Wolz, L., Pourtsidou, A., & Bacon, D. (2019). Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys. Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/stz1916

Vancouver

Cunnington S, Wolz L, Pourtsidou A, Bacon D. Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys. Monthly Notices of the Royal Astronomical Society. 2019 Jul 11. https://doi.org/10.1093/mnras/stz1916

Author

Cunnington, Steven ; Wolz, Laura ; Pourtsidou, Alkistis ; Bacon, David. / Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys. In: Monthly Notices of the Royal Astronomical Society. 2019.

Bibtex

@article{e73e23298e994e5daa871d3c3168a2ea,
title = "Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys",
abstract = " The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (HI) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the 21cm foreground emission that contaminates the cosmological HI signal. Using N-body simulations we simulate HI intensity maps and optical catalogues which share the same underlying cosmology. Adding simulated foreground contamination and using state-of-the-art reconstruction techniques we investigate the impacts that 21cm foregrounds and other systematics have on these cross-correlations. We find that the impact a FASTICA 21cm foreground clean has on the cross-correlations with spectroscopic optical surveys with well-constrained redshifts is minimal. However, problems arise when photometric surveys are considered: we find that a redshift uncertainty {\sigma}_z {\geq} 0.04 causes significant degradation in the cross power spectrum signal. We diagnose the main root of these problems, which relates to arbitrary amplitude changes along the line-of-sight in the intensity maps caused by the foreground clean and suggest solutions which should be applicable to real data. These solutions involve a reconstruction of the line-of-sight temperature means using the available overlapping optical data along with an artificial extension to the HI data through redshift to address edge effects. We then put these solutions through a further test in a mock experiment that uses a clustering-based redshift estimation technique to constrain the photometric redshifts of the optical sample. We find that with our suggested reconstruction, cross-correlations can be utilized to make an accurate prediction of the optical redshift distribution. ",
keywords = "astro-ph.CO",
author = "Steven Cunnington and Laura Wolz and Alkistis Pourtsidou and David Bacon",
note = "Version 2 - accepted for publication on 5th July 2019 in Monthly Notices of the Royal Astronomical Society Main Journal",
year = "2019",
month = jul,
day = "11",
doi = "10.1093/mnras/stz1916",
language = "Undefined",
journal = "Royal Astronomical Society. Monthly Notices",
issn = "1365-2966",
publisher = "Oxford University Press",

}

RIS

TY - JOUR

T1 - Impact of Foregrounds on HI Intensity Mapping Cross-Correlations with Optical Surveys

AU - Cunnington, Steven

AU - Wolz, Laura

AU - Pourtsidou, Alkistis

AU - Bacon, David

N1 - Version 2 - accepted for publication on 5th July 2019 in Monthly Notices of the Royal Astronomical Society Main Journal

PY - 2019/7/11

Y1 - 2019/7/11

N2 - The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (HI) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the 21cm foreground emission that contaminates the cosmological HI signal. Using N-body simulations we simulate HI intensity maps and optical catalogues which share the same underlying cosmology. Adding simulated foreground contamination and using state-of-the-art reconstruction techniques we investigate the impacts that 21cm foregrounds and other systematics have on these cross-correlations. We find that the impact a FASTICA 21cm foreground clean has on the cross-correlations with spectroscopic optical surveys with well-constrained redshifts is minimal. However, problems arise when photometric surveys are considered: we find that a redshift uncertainty {\sigma}_z {\geq} 0.04 causes significant degradation in the cross power spectrum signal. We diagnose the main root of these problems, which relates to arbitrary amplitude changes along the line-of-sight in the intensity maps caused by the foreground clean and suggest solutions which should be applicable to real data. These solutions involve a reconstruction of the line-of-sight temperature means using the available overlapping optical data along with an artificial extension to the HI data through redshift to address edge effects. We then put these solutions through a further test in a mock experiment that uses a clustering-based redshift estimation technique to constrain the photometric redshifts of the optical sample. We find that with our suggested reconstruction, cross-correlations can be utilized to make an accurate prediction of the optical redshift distribution.

AB - The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (HI) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the 21cm foreground emission that contaminates the cosmological HI signal. Using N-body simulations we simulate HI intensity maps and optical catalogues which share the same underlying cosmology. Adding simulated foreground contamination and using state-of-the-art reconstruction techniques we investigate the impacts that 21cm foregrounds and other systematics have on these cross-correlations. We find that the impact a FASTICA 21cm foreground clean has on the cross-correlations with spectroscopic optical surveys with well-constrained redshifts is minimal. However, problems arise when photometric surveys are considered: we find that a redshift uncertainty {\sigma}_z {\geq} 0.04 causes significant degradation in the cross power spectrum signal. We diagnose the main root of these problems, which relates to arbitrary amplitude changes along the line-of-sight in the intensity maps caused by the foreground clean and suggest solutions which should be applicable to real data. These solutions involve a reconstruction of the line-of-sight temperature means using the available overlapping optical data along with an artificial extension to the HI data through redshift to address edge effects. We then put these solutions through a further test in a mock experiment that uses a clustering-based redshift estimation technique to constrain the photometric redshifts of the optical sample. We find that with our suggested reconstruction, cross-correlations can be utilized to make an accurate prediction of the optical redshift distribution.

KW - astro-ph.CO

U2 - 10.1093/mnras/stz1916

DO - 10.1093/mnras/stz1916

M3 - Article

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 1365-2966

ER -