2006/07/24 by Jun-Mein Wu, Keiichi Umetsu, Wu, Jun-Mein +5
Decision Sciences · Engineering · #Advanced Measurement and Metrology Techniques #Advanced Sensor Technologies Research #Astrophysics (astro-ph) #FOS: Physical sciences #Scientific Measurement and Uncertainty Evaluation
paper · pdf · doi:10.48550/arxiv.astro-ph/0607542
openalex publication_date 2006/07/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The technique of weak-lensing aperture mass densitometry, so called the zeta-statistic, has recently been popular in actual observations for measurement of individual cluster mass. It has however been anticipated that the line-of-sight projection by foreground and background matter can adversely affect the cluster mass determination with not only substantial error dispersion but also a sizable positive systematic bias. Additionally, the finite number of background galaxies even at a reasonable observing depth can also introduce Poisson noise to the mass estimate. In this paper, we quantitatively investigate the degree of errors separately contributed by the two sources to the mass determination of those galaxy clusters with M200>1014M\odot. We find that the aperture mass of zeta-statistic turns out to be a mass estimator of much reduced systematic bias, due to the cancellation by the positively biased local background mass sheet. However, the error dispersion of M200 arising from both projection effect and Poisson noise is found to be still sizable (40%-90%), even for the shear-selected, clean sample where multiple clusters located within a suitable projected aperture are removed. We also investigate how to remedy this large-error problem in weak lensing measurements, and propose a plausible alternative mass estimator, M(