Illuminating Dark Energy with Cosmic Shear

Abstract

One of the principal goals of modern cosmology is to constrain the properties of dark energy. At present, numerous surveys are aiming to determine the equation of state, which is assumed constant due to our poor understanding of its behaviour (and since higher order parameterisations lead to unwieldy errors). This raises the question - how does our "best-fit" equation of state relate to the true function, which may vary with redshift. Saini et al. have demonstrated that the value of w attained by a supernovae study is well described by a weighted integral over the true function. Adopting a similar approach, we calculate the corresponding "weight function" for a fiducial cosmic shear survey. We disentangle contributions from the angular diameter distance and the growth factor, finding that they partially cancel each other out. Consequentially, the sensitivity to w at high redshift is enhanced beyond that of supernovae studies, and is comparable, if not higher, than lensing of the CMB. This illustrates the comlementary nature of the different techniques. Furthermore, we find that results which would naively be interpreted as inconsistent could arise from a time-dependent equation of state.

9 pages, 11 figures. Accepted for publication by Phys. Rev. D

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Cited by in corpus (23)

• Origins of weak lensing systematics, and requirements on future instrumentation (or knowledge of instrumentation)
• Two Windows on Acceleration and Gravitation: Dark Energy or New Gravity?
• Probing dark energy with cluster counts and cosmic shear power spectra: including the full covariance
• Tracking quintessence by cosmic shear - Constraints from VIRMOS-Descart and CFHTLS and future prospects
• The effect of modified gravity on weak lensing
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• Geometry and growth contributions to cosmic shear observables
• The Physical Origin of Dark Energy Constraints from Rubin Observatory and CMB-S4 Lensing Tomography
• Expressing the equation of state parameter in terms of the three dimensional cosmic shear
• Observing Baryon Oscillations with Cosmic Shear
• Redshift Sensitivity of the Kaiser Effect
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