Testing the reliability of weak lensing cluster detections

¹ ITA, Zentrum für Astronomie, Universität Heidelberg, Albert Überle Str. 2, 69120 Heidelberg, Germany e-mail: francesco@ita.uni-heidelberg.de
² INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
³ Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna, Italy
⁴ INFN-National Institute for Nuclear Physics, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
⁵ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching bei Muenchen, Germany

Received: 1 February 2007
Accepted: 9 June 2007

Abstract

We study the reliability of dark-matter halo detections with three different linear filters applied to weak-lensing data. We use ray-tracing in the multiple lens-plane approximation through a large cosmological simulation to construct realizations of cosmic lensing by large-scale structures between redshifts zero and two. We apply the filters mentioned above to detect peaks in the weak-lensing signal and compare them with the true population of dark matter halos present in the simulation. We confirm the stability and performance of a filter optimised for suppressing the contamination by large-scale structure. It allows the reliable detection of dark-matter halos with masses above a few times with a fraction of spurious detections below ~. For sources at redshift two, 50% of the halos more massive than ~ are detected, and completeness is reached at ~.