Optimal Galaxy Shape Measurements for Weak Lensing Applications Using the Hubble Space Telescope Advanced Camera for Surveys
Abstract
We present three-epoch multiband (V606, i775, and z850) measurements of galaxy shapes using the ``polar shapelet'' or Laguerre expansions method with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) data, obtained as part of the Great Observatories Origin Deep Survey (GOODS). We take advantage of the unique features of the GOODS/ACS fields to test the reliability of this relatively new method of galaxy shape measurement for weak lensing analysis and to quantify the impact of the ACS point-spread function (PSF) on HST/ACS data. We estimate the bias introduced by the sharp PSF of the ACS on shape measurement. We show that the bias in the tangential shear due to galaxy-galaxy lensing can be safely neglected provided that only well-resolved galaxies are used, while it would be comparable to the signal level (1%-3%) for cosmic shear measurements. These results should be of general utility in planning and analyzing weak lensing measurements with HST/ACS data.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2004
- DOI:
- 10.1086/379697
- arXiv:
- arXiv:astro-ph/0309333
- Bibcode:
- 2004ApJ...600L.159P
- Keywords:
-
- Cosmology: Dark Matter;
- Galaxies: Halos;
- Cosmology: Gravitational Lensing;
- Cosmology: Large-Scale Structure of Universe;
- Methods: Data Analysis;
- Astrophysics
- E-Print:
- 12 pages, 3 figures. Accepted for ApJL