English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Weak gravitational lensing causes subtle changes in the apparent shapes ofgalaxies due to the bending of light by the gravity of foreground masses. Bymeasuring the shapes of large numbers of galaxies (millions in recent surveys,up to tens of billions in future surveys) we can infer the parameters thatdetermine cosmology. Imperfections in the detectors used to record images ofthe sky can introduce changes in the apparent shape of galaxies, which in turncan bias the inferred cosmological parameters. In this paper we consider theeffect of two widely discussed sensor imperfections: tree-rings, due toimpurity gradients which cause transverse electric fields in the Charge-CoupledDevices (CCD), and pixel-size variation, due to periodic CCD fabricationerrors. These imperfections can be observed when the detectors are subject touniform illumination (flat field images). We develop methods to determine thespurious shear and convergence (due to the imperfections) from the flat-fieldimages. We calculate how the spurious shear when added to the lensing shearwill bias the determination of cosmological parameters. We apply our methods tocandidate sensors of the Large Synoptic Survey Telescope (LSST) as a timely andimportant example, analyzing flat field images recorded with LSST prototypeCCDs in the laboratory. We find that tree-rings and periodic pixel-sizevariation present in the LSST CCDs will introduce negligible bias tocosmological parameters determined from the lensing power spectrum,specifically w, {\Omega}m and {\sigma}8.

Consequences of CCD imperfections for cosmology determined by weak lensing surveys: From laboratory measurements to cosmological parameter bias