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arXiv · 0907.3635

Delensing Gravitational Wave Standard Sirens with Shear and Flexion Maps

Charles Shapiro·David Bacon·Martin Hendry·Ben Hoyle
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Abstract

Supermassive black hole binary systems (SMBHB) are standard sirens -- the gravitational wave analogue of standard candles -- and if discovered by gravitational wave detectors, they could be used as precise distance indicators. Unfortunately, gravitational lensing will randomly magnify SMBHB signals, seriously degrading any distance measurements. Using a weak lensing map of the SMBHB line of sight, we can estimate its magnification and thereby remove some uncertainty in its distance, a procedure we call "delensing." We find that delensing is significantly improved when galaxy shears are combined with flexion measurements, which reduce small-scale noise in reconstructed magnification maps. Under a Gaussian approximation, we estimate that delensing with a 2D mosaic image from an Extremely Large Telescope (ELT) could reduce distance errors by about 30-40% for a SMBHB at z=2. Including an additional wide shear map from a space survey telescope could reduce distance errors by 50%. Such improvement would make SMBHBs considerably more valuable as cosmological distance probes or as a fully independent check on existing probes.

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Charles Shapiro, David Bacon, Martin Hendry, Ben Hoyle. 2009-07-21. Delensing Gravitational Wave Standard Sirens with Shear and Flexion Maps. https://doi.org/10.1111/j.1365-2966.2010.16317.x

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