Effect of aberration on partial-sky measurements of the cosmic microwave background temperature power spectrum

Donghui Jeong, Jens Chluba, Liang Dai, Marc Kamionkowski, Xin Wang

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Our motion relative to the cosmic microwave background (CMB) rest frame deflects light rays giving rise to shifts as large as ℓ→ℓ(1± β), where β=0.00123 is our velocity (in units of the speed of light) on measurements of CMB fluctuations. Here we present a novel harmonic-space approach to this CMB aberration that improves upon prior work by allowing us to (i) go to higher orders in β, thus extending the validity of the analysis to measurements at ℓâ‰β-1â‰800; and (ii) treat the effects of window functions and pixelization in a more accurate and computationally efficient manner. We calculate precisely the magnitude of the systematic bias in the power spectrum inferred from the partial sky and show that aberration shifts the multipole moment by Δℓ/ℓ cos, with cos averaged over the survey footprint. Such a shift, if ignored, would bias the measurement of the sound-horizon size θ* at the 0.01% level, which is comparable to the measurement uncertainties of Planck. The bias can then propagate into cosmological parameters such as the angular-diameter distance, Hubble parameter and dark-energy equation of state. We study the effect of aberration for current Planck, South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) data and show that the bias cannot be neglected. On the other hand, the aberration effect yields the opposite sign of the discrepancy and cannot account for the small tension between ACT and SPT. An Appendix shows how the near constancy of the full-sky power spectrum under aberration follows from unitarity of the aberration kernel.

Original languageEnglish (US)
Article number023003
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume89
Issue number2
DOIs
StatePublished - Jan 16 2014

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sky
power spectra
aberration
microwaves
telescopes
cosmology
temperature
shift
poles
footprints
dark energy
multipoles
horizon
rays
equations of state
moments
harmonics
acoustics

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

Cite this

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title = "Effect of aberration on partial-sky measurements of the cosmic microwave background temperature power spectrum",
abstract = "Our motion relative to the cosmic microwave background (CMB) rest frame deflects light rays giving rise to shifts as large as ℓ→ℓ(1± β), where β=0.00123 is our velocity (in units of the speed of light) on measurements of CMB fluctuations. Here we present a novel harmonic-space approach to this CMB aberration that improves upon prior work by allowing us to (i) go to higher orders in β, thus extending the validity of the analysis to measurements at ℓ{\^a}‰β-1{\^a}‰800; and (ii) treat the effects of window functions and pixelization in a more accurate and computationally efficient manner. We calculate precisely the magnitude of the systematic bias in the power spectrum inferred from the partial sky and show that aberration shifts the multipole moment by Δℓ/ℓ cos, with cos averaged over the survey footprint. Such a shift, if ignored, would bias the measurement of the sound-horizon size θ* at the 0.01{\%} level, which is comparable to the measurement uncertainties of Planck. The bias can then propagate into cosmological parameters such as the angular-diameter distance, Hubble parameter and dark-energy equation of state. We study the effect of aberration for current Planck, South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) data and show that the bias cannot be neglected. On the other hand, the aberration effect yields the opposite sign of the discrepancy and cannot account for the small tension between ACT and SPT. An Appendix shows how the near constancy of the full-sky power spectrum under aberration follows from unitarity of the aberration kernel.",
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Effect of aberration on partial-sky measurements of the cosmic microwave background temperature power spectrum. / Jeong, Donghui; Chluba, Jens; Dai, Liang; Kamionkowski, Marc; Wang, Xin.

In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 89, No. 2, 023003, 16.01.2014.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of aberration on partial-sky measurements of the cosmic microwave background temperature power spectrum

AU - Jeong, Donghui

AU - Chluba, Jens

AU - Dai, Liang

AU - Kamionkowski, Marc

AU - Wang, Xin

PY - 2014/1/16

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AB - Our motion relative to the cosmic microwave background (CMB) rest frame deflects light rays giving rise to shifts as large as ℓ→ℓ(1± β), where β=0.00123 is our velocity (in units of the speed of light) on measurements of CMB fluctuations. Here we present a novel harmonic-space approach to this CMB aberration that improves upon prior work by allowing us to (i) go to higher orders in β, thus extending the validity of the analysis to measurements at ℓâ‰β-1â‰800; and (ii) treat the effects of window functions and pixelization in a more accurate and computationally efficient manner. We calculate precisely the magnitude of the systematic bias in the power spectrum inferred from the partial sky and show that aberration shifts the multipole moment by Δℓ/ℓ cos, with cos averaged over the survey footprint. Such a shift, if ignored, would bias the measurement of the sound-horizon size θ* at the 0.01% level, which is comparable to the measurement uncertainties of Planck. The bias can then propagate into cosmological parameters such as the angular-diameter distance, Hubble parameter and dark-energy equation of state. We study the effect of aberration for current Planck, South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) data and show that the bias cannot be neglected. On the other hand, the aberration effect yields the opposite sign of the discrepancy and cannot account for the small tension between ACT and SPT. An Appendix shows how the near constancy of the full-sky power spectrum under aberration follows from unitarity of the aberration kernel.

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