LensingETC: a tool to optimize multi-filter imaging campaigns of galaxy-scale strong lensing systems

TL;DR

LensingETC is a tool designed to optimize multi-filter imaging strategies for galaxy-scale strong lensing systems, improving observational efficiency and parameter constraint accuracy in astrophysical research.

Contribution

The paper introduces LensingETC, a novel simulation and modeling tool that optimizes telescope time for strong lensing imaging campaigns, accounting for instrument specifics and data quality.

Findings

Higher resolution improves lens parameter constraints over SNR trade-offs.

Sub-Nyquist PSF sampling affects the robustness and scatter of lens parameter recovery.

Optimized two-filter strategies enhance observational efficiency within limited telescope time.

Abstract

Imaging data is the principal observable required to use galaxy-scale strong lensing in a multitude of applications in extragalactic astrophysics and cosmology. In this paper, we develop Lensing Exposure Time Calculator (LensingETC) to optimize the efficiency of telescope time usage when planning multi-filter imaging campaigns for galaxy-scale strong lenses. This tool simulates realistic data tailored to specified instrument characteristics and then automatically models them to assess the power of the data in constraining lens model parameters. We demonstrate a use case of this tool by optimizing a two-filter observing strategy (in IR and UVIS) within the limited exposure time per system allowed by a Hubble Space Telescope (HST) Snapshot program. We find that higher resolution is more advantageous to gain constraining power on the lensing observables, when there is a trade-off between signal-to-noise ratio and resolution; e.g., between the UVIS and IR filters of the HST. We also find that, whereas a point spread function (PSF) with sub-Nyquist sampling allows the sample mean for a model parameter to be robustly recovered for both galaxy-galaxy and point-source lensing systems, a sub-Nyquist sampled PSF introduces a larger scatter than a Nyquist sampled one in the deviation from the ground truth for point-source lens systems.