| Full text | |
| Author(s): |
Cypriano, E. S.
[1, 2]
;
Amara, A.
[3]
;
Voigt, L. M.
[1]
;
Bridle, S. L.
[1]
;
Abdalla, F. B.
[1]
;
Refregier, A.
[4]
;
Seiffert, M.
[5, 6]
;
Rhodes, J.
[5, 6]
Total Authors: 8
|
| Affiliation: | [1] UCL, Dept Phys & Astron, London WC1E 6BT - England
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Astron, BR-05508900 Sao Paulo - Brazil
[3] ETH, Dept Phys, CH-8093 Zurich - Switzerland
[4] CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette - France
[5] CALTECH, Pasadena, CA 91125 - USA
[6] CALTECH, Jet Prop Lab, Pasadena, CA 91109 - USA
Total Affiliations: 6
|
| Document type: | Journal article |
| Source: | Monthly Notices of the Royal Astronomical Society; v. 405, n. 1, p. 494-502, JUN 11 2010. |
| Web of Science Citations: | 22 |
| Abstract | |
Cosmic shear requires high precision measurement of galaxy shapes in the presence of the observational point spread function (PSF) that smears out the image. The PSF must therefore be known for each galaxy to a high accuracy. However, for several reasons, the PSF is usually wavelength dependent; therefore, the differences between the spectral energy distribution of the observed objects introduce further complexity. In this paper, we investigate the effect of the wavelength dependence of the PSF, focusing on instruments in which the PSF size is dominated by the diffraction limit of the telescope and which use broad-band filters for shape measurement. We first calculate biases on cosmological parameter estimation from cosmic shear when the stellar PSF is used uncorrected. Using realistic galaxy and star spectral energy distributions and populations and a simple three-component circular PSF, we find that the colour dependence must be taken into account for the next generation of telescopes. We then consider two different methods for removing the effect: (i) the use of stars of the same colour as the galaxies and (ii) estimation of the galaxy spectral energy distribution using multiple colours and using a telescope model for the PSF. We find that both of these methods correct the effect to levels below the tolerances required for per cent level measurements of dark energy parameters. Comparison of the two methods favours the template-fitting method because its efficiency is less dependent on galaxy redshift than the broad-band colour method and takes full advantage of deeper photometry. (AU) | |
| FAPESP's process: | 09/07154-8 - A study of galaxy clusters and cosmology through gravitational lensing and other techniques |
| Grantee: | Eduardo Serra Cypriano |
| Support Opportunities: | Regular Research Grants |