Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmological weak lensing with the HST GEMS survey   We present our cosmic shear analysis of GEMS, one of the largest wide-field
surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced
Camera for Surveys (ACS), GEMS spans 795 square arcmin in the Chandra Deep
Field South. We detect weak lensing by large-scale structure in high resolution
F606W GEMS data from ~60 resolved galaxies per square arcminute. We measure the
two-point shear correlation function, the top-hat shear variance and the shear
power spectrum, performing an E/B mode decomposition for each statistic. We
show that we are not limited by systematic errors and use our results to place
joint constraints on the matter density parameter Omega_m and the amplitude of
the matter power spectrum sigma_8. We find sigma_8(Omega_m/0.3)^{0.65}=0.68 +/-
0.13 where the 1sigma error includes both our uncertainty on the median
redshift of the survey and sampling variance.
  Removing image and point spread function (PSF) distortions are crucial to all
weak lensing analyses. We therefore include a thorough discussion on the degree
of ACS PSF distortion and anisotropy which we characterise directly from GEMS
data. Consecutively imaged over 20 days, GEMS data also allows us to
investigate PSF instability over time. We find that, even in the relatively
short GEMS observing period, the ACS PSF ellipticity varies at the level of a
few percent which we account for with a semi-time dependent PSF model. Our
correction for the temporal and spatial variability of the PSF is shown to be
successful through a series of diagnostic tests.

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The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat