Tomographic Magnification of Lyman Break Galaxies in The Deep Lens Survey

TL;DR

This study detects and analyzes gravitational magnification of high-redshift Lyman Break Galaxies using deep survey data, confirming the effect's significance and consistency with cosmological models.

Contribution

First detection of gravitational magnification of z > 4 Lyman Break Galaxies using tomographic analysis in the Deep Lens Survey, with a novel bias-independent estimator.

Findings

Magnification signal detected at S/N > 20.

Results consistent with WMAP7 {5}CDM cosmology.

Rejects flat dark matter dominated universe at > 7.5c3.

Abstract

Using about 450,000 galaxies in the Deep Lens Survey, we present a detection of the gravitational magnification of z > 4 Lyman Break Galaxies by massive foreground galaxies with 0.4 < z < 1.0, grouped by redshift. The magnification signal is detected at S/N greater than 20, and rigorous checks confirm that it is not contaminated by any galaxy sample overlap in redshift. The inferred galaxy mass profiles are consistent with earlier lensing analyses at lower redshift. We then explore the tomographic lens magnification signal by splitting our foreground galaxy sample into 7 redshift bins. Combining galaxy-magnification cross-correlations and galaxy angular auto-correlations, we develop a bias-independent estimator of the tomographic signal. As a diagnostic of magnification tomography, the measurement of this estimator rejects a flat dark matter dominated Universe at > 7.5{\sigma} with a fixed \sigma_8 and is found to be consistent with the expected redshift-dependence of the WMAP7 {\Lambda}CDM cosmology.