We present parameter estimation forecasts for present and future 3D cosmic shear surveys .
We demonstrate in particular that , in conjunction with results from cosmic microwave background ( CMB ) experiments , the properties of dark energy can be estimated with very high precision with large-scale , fully 3D weak lensing surveys .
In particular , a 5-band , 10,000 square degree ground-based survey of galaxies to a median redshift of z _ { m } = 0.7 could achieve 1 - \sigma marginal statistical errors , in combination with the constraints expected from the CMB Planck Surveyor , of \Delta w _ { 0 } = 0.108 and \Delta w _ { a } = 0.099 .
We parameterize the redshift evolution of w by w ( a ) = w _ { 0 } + w _ { a } ( 1 - a ) where a is the scale factor .
Such a survey is achievable with a wide-field camera on a 4 metre class telescope .
The error on the value of w at an intermediate pivot redshift of z = 0.368 is constrained to \Delta w ( z = 0.368 ) = 0.0175 .
We compare and combine the 3D weak lensing constraints with the cosmological and dark energy parameters measured from planned Baryon Acoustic Oscillation ( BAO ) and supernova Type Ia experiments , and find that 3D weak lensing significantly improves the marginalized errors on w _ { 0 } and w _ { a } in combination , and provides constraints on w ( z ) at a unique redshift through the lensing effect .
A combination of 3D weak lensing , CMB and BAO experiments could achieve \Delta w _ { 0 } = 0.037 and \Delta w _ { a } = 0.099 .
We also show how our results can be scaled to other telescopes and survey designs .
Fully 3D weak shear analysis avoids the loss of information inherent in tomographic binning , and we also show that the sensitivity to systematic errors in photometric redshift is much less .
In conjunction with the fact that the physics of lensing is very soundly based , the analysis here demonstrates that deep , wide-angle 3D weak lensing surveys are extremely promising for measuring dark energy properties .