A GPU-Enabled, High-Resolution Cosmological Microlensing Parameter Survey

Abstract

In the era of synoptic surveys, the number of known gravitationally lensed quasars is set to increase by over an order of magnitude. These new discoveries will enable a move from single-quasar studies to investigations of statistical samples, presenting new opportunities to test theoretical models for the structure of quasar accretion discs and broad emission line regions (BELRs). As one crucial step in preparing for this influx of new lensed systems, a large-scale exploration of microlensing convergence-shear parameter space is warranted, requiring the computation of O(10^5) high resolution magnification maps. Based on properties of known lensed quasars, and expectations from accretion disc/BELR modelling, we identify regions of convergence-shear parameter space, map sizes, smooth matter fractions, and pixel resolutions that should be covered. We describe how the computationally time-consuming task of producing ~290000 magnification maps with sufficient resolution (10000^2 pixel/map) to probe scales from the inner edge of the accretion disc to the BELR can be achieved in ~400 days on a 100 teraflop/s high performance computing facility, where the processing performance is achieved with graphics processing units. We illustrate a use-case for the parameter survey by investigating the effects of varying the lens macro-model on accretion disc constraints in the lensed quasar Q2237+0305. We find that although all constraints are consistent within their current error bars, models with more densely packed microlenses tend to predict shallower accretion disc radial temperature profiles. With a large parameter survey such as the one described here, such systematics on microlensing measurements could be fully explored.

30 pages, 3 figures, accepted for publication in ApJ

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Cited by in corpus (10)

• Microlensing of the broad line region in 17 lensed quasars
• GERLUMPH Data Release 1: High-resolution cosmological microlensing magnification maps and eResearch tools
• HST imaging of four gravitationally lensed quasars
• A new parameter space study of cosmological microlensing
• Adventures in the microlensing cloud: large datasets, eResearch tools, and GPUs
• Effects of Kerr Strong Gravity on Quasar X-ray Microlensing
• The effect of macromodel uncertainties on microlensing modelling of lensed quasars
• FRBs Lensed by Point Masses II. The multi-peaked FRBs from the point view of microlensing
• Simulating time-varying strong lenses
• A joint microlensing analysis of lensing mass and accretion disc models