Grale Based Reconstructions of Gravitational Lens Models of Synthetic Galaxy Clusters
Future of Free-form Reconstruction Methods.
Related Publication:
Free-form GRALE lens inversion of galaxy clusters with up to 1000 multiple images,Agniva Ghosh, Liliya L R Williams and Jori Liesenborgs, 2020, MNRAS, 494, 3998.
With contemporary telescopes like the Hubble Space Telescope, the number of lensed images observed in a cluster of galaxies is about 100. In the near future, this number will be increased almost by an order of magnitude, with the introduction of new space based telescopes like the James Webb Space Telescope. This will further refine our view of the clusters leading to a more accurate and precise mapping of the total and dark matter distribution in clusters. However, to leverage this increased number of images requires re-evaluation of the performance of the existing reconstruction methods.
We scrutinized the performance of Grale in the regime of \( 150-1000\) input images, using synthetic galaxy clusters (Ghosh et al. 2020). The results show that with an increasing number of input images, Grale produces improved reconstructed mass distributions, with the fraction of the lens plane recovered at better than \( 10\%\) accuracy increasing from \( 40-50 \% \) for \( \sim 150 \) images to \( 65\% \) for \( \sim 1000\) images (see Figure 1). The reconstructed time delays imply a more precise measurement of the Hubble Constant \( (H_0) \), with \( \le 1 \% \) bias. While the fidelity of the reconstruction improves with the increasing number of multiple images used as model constraints, \( \sim 150\) to \( \sim 1000\), the lens plane rms of the image positions for the reconstructed mass distributions deteriorates from \( \sim 0.11\) arcseconds to \( \sim 0.28\) arcseconds. Since lens plane rms is not necessarily the best indicator of the quality of the mass reconstructions, looking for an alternative indicator is warranted.
