Lensing by Lyman Limit Systems: Determining the Mass to Gas Ratio

Abstract

We present a new method to determine the total mass-to-neutral gas ratio in Lyman-limits systems. The method exploits the relation between the neutral hydrogen column density and the magnification of background sources due to the weak gravitational lensing that these systems induce. Because weak lensing does not provide a direct measure of mass, one must use this relation in a statistical sense to solve for the average mass-to-gas ratio and its distribution. We use a detailed mock catalog of quasars (sources) and Lyman-limit systems (lenses) to demonstrate the applicability of this approach through our ability to recover the parameter. This mock catalog also allows us to check for systematics in the method and to sketch its limitations. For a universal constant mass-to-gas ratio and a sample of N quasars, we obtain an unbiased estimate of its value with 95% confidence limits (independent of its actual value) of +/- 140 {10^5/N)^0.5.

20 pages, 11 figures submitted to ApJ

References in corpus (5)

• Weak Gravitational Lensing
• The 2dF QSO Redshift Survey - I. The Optical QSO Luminosity Function
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• Simulations of Damped Lyman-Alpha and Lyman Limit Absorbers in Different Cosmologies: Implications for Structure Formation at High Redshift
• QSO 0130-4021: A third QSO showing a low Deuterium to Hydrogen Abundance Ratio

Cited by in corpus (3)

• Multi-Phase Galaxy Formation: High Velocity Clouds and the Missing Baryon Problem
• Investigating lensing by absorbers in the 2dF-Quasar survey
• Detecting and interpreting statistical lensing by absorbers