11:30 am–12:00 pm ERC 401
The expected redshift distribution of strong lensing clusters places almost all cluster lenses at z<1. High redshift foreground cluster lensing (HRFCL) systems at z≥1 are thus a rare type of cluster-scale strong lensing. The COOL-LAMPS (ChicagO Optically-selected Lenses - Located At the Margins of Public Surveys) collaboration has discovered a sample of HRFCL candidates through its strong-lens-finding efforts. This thesis works to confirm and characterize these candidate systems. Using the DECaLS dr10 photometric and photo-z data and red sequence modelling data, I construct a method to accurately estimate the redshifts of foreground galaxy clusters that is consistent with spectroscopically confirmed redshift values. I also show lens models for several of the systems, when there is sufficient information in the ground-based discovery data to allow the construction of such. I then further compare two lensing properties of confirmed systems – specifically the length to width ratios of the arclets and the Einstein radii - of HRFCL systems to those of the Pipeline for Images of Cosmological Strong lensing (PICS) (Li et al. 2016) simulated group- and cluster-scale strong lensing systems at z≥0.9. This comparison, in which the confirmed systems are statistically indistinguishable from the simulations – strongly suggests that the PICS simulation generates lenses that are an accurate representation of the observed HRFCL systems, or conversely, if one anticipates that the simulations are correct, that the interpretation of these systems as strong lenses is broadly correct. Future analyses of these confirmed HRFCLs will allow for further inquiry into, among other things, the core mass structure, and the relationship between that and the assembling central galaxies. Also, it is worth noting that these high redshift lenses tend to lens high redshift galaxies; the median redshift of the lensed sources is z=2.93, significantly larger than the canonical z~2 seen in other cluster lens samples when considering bright lensed sources.
Advisor: Mike Gladders