**AAS 205th Meeting, 9-13 January 2005**

*Session 69 Cosmology: Population III, Distant SNe, and Dark Energy*

Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall
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## [69.14] Can cosmic shear tomography bring dark energy parameter constraints to a satisfactory level of precision?

*M. Ishak, D. N. Spergel (Princeton University)*

We present new results on how well cosmic shear tomography
can improve dark energy parameter constraints. In view of
the parameterization dependence problems, we probe the dark
energy using its density and also two variants of its
equation of state. For the former, we model the density as a
continuous function interpolated using 2 dimensionless
amplitude parameters evaluated at equally spaced redshits.
Unlike previous studies, we look here for combinations of
experiments that will bring the 2 sigma errors on these
parameters to a satisfactory level of precision, say 0.02.
Many dark energy models occupy a very narrow range of this
parameter sub-space, and only such precision will decisively
settle the question. For CMB, we consider future constraints
from one year of data from Planck, 8 years of data from
WMAP, and one year of data from the Atacama Cosmology
Telescope (ACT). We use two sets of 2000 supernovae with
maximum redshifts 0.8 and 1.5 respectively, and consider two
cosmic shear reference surveys: a wide survey with two
tomographic bins and a deep survey with 10 bins. The 2-sigma
constraints found from Planck, supernovae, and the wide
lensing survey are impressive but not enough to close the
question. When the deep survey with 10 bin tomography is
used, the constraints reduce to the required level of
precision. Thus, we find that after the combination of the
three probes, cosmic shear tomography with many bins and
several thousands square degrees can add the necessary
improvement to the constraints on dark energy. However, the
probes considered here are faced with serious systematic
effects that need to be well understood and tightly
controlled in order to match the statistical accuracy and
make these constraints achievable.

The author(s) of this abstract have provided an email address
for comments about the abstract:
mishak@princeton.edu

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