Dark Matter Structures In The Deep Lens Survey

TL;DR

This paper presents a weak lensing reconstruction of the Deep Lens Survey F2 field, identifying significant structures and estimating false positive rates using Monte Carlo simulations, revealing filamentary structures and potential underdensities.

Contribution

It introduces a regularized maximum likelihood method for weak lensing reconstruction and provides estimates of false detection rates in the survey data.

Findings

Detection of filamentary structures associated with optical clusters.

Estimated 10-25% false positive rate in lensing peaks.

Identification of a candidate underdensity with high significance.

Abstract

We present a regularized maximum likelihood weak lensing reconstruction of the Deep Lens Survey F2 field (4 deg^2). High signal-to-noise ratio peaks in our lensing significance map appear to be associated with possible projected filamentary structures. The largest apparent structure extends for over a degree in the field and has contributions from known optical clusters at three redshifts (z ~ 0.3, 0.43, 0.5). Noise in weak lensing reconstructions is known to potentially cause "false positives"; we use Monte Carlo techniques to estimate the contamination in our sample, and find that 10-25% of the peaks are expected to be false detections. For significant lensing peaks we estimate the total signal-to-noise ratio of detection using a method that accounts for pixel-to-pixel correlations in our reconstruction. We also report the detection of a candidate relative underdensity in the F2 field with a total signal-to-noise ratio of ~ 5.5.