Consequences of CCD imperfections for cosmology determined by weak lensing surveys: from laboratory measurements to cosmological parameter bias
- Nishina Center (RIKEN), Wako (Japan); Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center
- Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States); California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.
- Nishina Center (RIKEN), Wako (Japan)
Weak gravitational lensing causes subtle changes in the apparent shapes of galaxies due to the bending of light by the gravity of foreground masses. By measuring the shapes of large numbers of galaxies (millions in recent surveys, up to tens of billions in future surveys) we can infer the parameters that determine cosmology. Imperfections in the detectors used to record images of the sky can introduce changes in the apparent shape of galaxies, which in turn can bias the inferred cosmological parameters. Here in this paper we consider the effect of two widely discussed sensor imperfections: tree-rings, due to impurity gradients which cause transverse electric fields in the Charge-Coupled Devices (CCD), and pixel-size variation, due to periodic CCD fabrication errors. These imperfections can be observed when the detectors are subject to uniform illumination (flat field images). We develop methods to determine the spurious shear and convergence (due to the imperfections) from the flat-field images. We calculate how the spurious shear when added to the lensing shear will bias the determination of cosmological parameters. We apply our methods to candidate sensors of the Large Synoptic Survey Telescope (LSST) as a timely and important example, analyzing flat field images recorded with LSST prototype CCDs in the laboratory. In conclusion, we find that tree-rings and periodic pixel-size variation present in the LSST CCDs will introduce negligible bias to cosmological parameters determined from the lensing power spectrum, specifically w,Ωm and σ8.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Grant/Contract Number:
- SC0012704; AC02- 98CH10886; SC00112704
- OSTI ID:
- 1260145
- Alternate ID(s):
- OSTI ID: 1295207
- Report Number(s):
- BNL-112138-2016-JA; BNL-112370-2016-JA; KA2301020
- Journal Information:
- The Astrophysical Journal (Online), Vol. 825, Issue 1; ISSN 1538-4357
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Quantifying systematics from the shear inversion on weak-lensing peak counts
|
journal | June 2018 |
Similar Records
Weak Lensing by Galaxy Clusters: from Pixels to Cosmology
Effects of overlapping sources on cosmic shear estimation: Statistical sensitivity and pixel-noise bias