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research article

A new method to break the mass-sheet degeneracy using aperture moments

Rexroth, Markus  
•
Natarajan, Priyamvada
•
Kneib, Jean-Paul  
2016
Monthly Notices Of The Royal Astronomical Society

Mass determinations from gravitational lensing shear and the higher order estimator flexion are both subject to the mass-sheet degeneracy. Mass sheet degeneracy refers to a transformation that leaves the reduced shear and flexion invariant. In general, this transformation can be approximated by the addition of a constant surface mass density sheet. We propose a new technique to break the mass-sheet degeneracy. The method uses mass moments of the shear or flexion fields in combination with convergence information derived from number counts which exploit the magnification bias. The difference between the measured mass moments provides an estimator for the magnitude of the additive constant that is the mass sheet. For demonstrating this, we derive relations that hold true in general for nth order moments and show how they can be employed effectively to break the degeneracy. We investigate the detectability of this degeneracy parameter from our method and find that the degeneracy parameter can be feasibly determined from stacked galaxy-galaxy lensing data and cluster lensing data. Furthermore, we compare the signal-to-noise ratios of convergence information from number counts with shear and flexion for singular isothermal sphere and Navarro-Frenk-White models. We find that the combination of shear and flexion performs best on galaxy and cluster scales and the convergence information can therefore be used to break the mass-sheet degeneracy without quality loss in the mass reconstruction. In summary, there is power in the combination of shear, flexion, convergence and their higher order moments. With the anticipated wealth of lensing data from upcoming and future satellite missions - EUCLID and WFIRST - this technique will be feasible.

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Type
research article
DOI
10.1093/mnras/stw1017
Web of Science ID

WOS:000381204600017

Author(s)
Rexroth, Markus  
Natarajan, Priyamvada
Kneib, Jean-Paul  
Date Issued

2016

Publisher

Oxford Univ Press

Published in
Monthly Notices Of The Royal Astronomical Society
Volume

460

Issue

3

Start page

2505

End page

2525

Subjects

gravitational lensing: weak

•

galaxies: clusters: general

•

galaxies: haloes

•

dark matter

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
IPEP  
Available on Infoscience
October 18, 2016
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/130344
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