2024/10/16 by Samuel C. Lange, Aristeidis Amvrosiadis, Lange, Samuel C. +21 · 1 voice · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Adaptive optics and wavefront sensing #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2410.12987
We analyze two galaxy-scale strong gravitational lenses, SPT0418-47 and SPT2147-50, using JWST NIRCam imaging across multiple filters. To account for angular complexity in the lens mass distribution, we introduce multipole perturbations with orders m=1, 3, 4. Our results show strong evidence for angular mass complexity in SPT2147, with multipole strengths of 0.3-1.7 % for m=3, 4 and 2.4-9.5 % for m=1, while SPT0418 shows no such preference. We also test lens models that include a dark matter substructure, finding a strong preference for a substructure in SPT2147-50 with a Bayes factor (log-evidence change) of ∼ 60 when multipoles are not included. Including multipoles reduces the Bayes factor to ∼ 11, still corresponding to a 5σ detection of a subhalo with an NFW mass of log10(M200/M\odot) = 10.87\substack+0.53 -0.71. While SPT2147-50 may represent the fourth detection of a dark matter substructure in a strong lens, further analysis is needed to confirm that the signal is not due to systematics associated with the lens mass model.