STRIDES: automated uniform models for 30 quadruply imaged quasars

Abstract

Gravitational time delays provide a powerful one step measurement of H0, independent of all other probes. One key ingredient in time delay cosmography are high accuracy lens models. Those are currently expensive to obtain, both, in terms of computing and investigator time (105 − 6 CPU hours and ∼0.5–1 year, respectively). Major improvements in modeling speed are therefore necessary to exploit the large number of lenses that are forecast to be discovered over the current decade. In order to bypass this roadblock, we develop an automated modeling pipeline and apply it to a sample of 31 lens systems, observed by the Hubble Space Telescope in multiple bands. Our automated pipeline can derive models for 30/31 lenses with few hours of human time and <100 CPU hours of computing time for a typical system. For each lens, we provide measurements of key parameters and predictions of magnification as well as time delays for the multiple images. We characterize the cosmography-readiness of our models using the stability of differences in Fermat potential (proportional to time delay) w.r.t. modeling choices. We find that for 10/30 lenses our models are cosmography or nearly cosmography grade (<3 per cent and 3-5 per cent variations). For 6/30 lenses the models are close to cosmography grade (5-10 per cent). These results utilize informative priors and will need to be confirmed by further analysis. However, they are also likely to improve by extending the pipeline modeling sequence and options. In conclusion, we show that uniform cosmography grade modeling of large strong lens samples is within reach.

A Highly Magnified Gravitationally Lensed Red QSO at z = 2.5 with a Significant Flux Ratio Anomaly

“…We note that, in a program to study a sample of 30 lensed QSOs with HST (Cycle 26, Program ID 15652; PI: Treu), W2M J1042+1641 was imaged in the F475X and F814W filters with WFC3/UVIS. Schmidt et al (2023) modeled this system as part of the sample using an automated pipeline using the LENSTRONOMY software package (Birrer & Amara 2018) with a power-law elliptical mass distribution plus external shear. The fitting was done simultaneously for the two UVIS bands plus the F160W data from this work, and the F125W data were not used.…”

LensWatch. I. Resolved HST Observations and Constraints on the Strongly Lensed Type Ia Supernova 2022qmx (“SN Zwicky”)

“…The modularity of LENSTRONOMY supports imaging modeling as well as catalog-based model fitting. LENSTRONOMY has been applied for time-delay cosmography of lensed quasars (Birrer et al 2019;Shajib et al 2020) and lensed SNe as well as a variety of other lens modeling and image analysis applications (Gilman et al 2020;Shajib et al 2021;Schmidt et al 2022).…”

Identification of Galaxy–Galaxy Strong Lens Candidates in the DECam Local Volume Exploration Survey Using Machine Learning

“…In all cases, the uncertainty is summed in quadrature with the DECam pixel scale (0 263 pixel −1 ). For systems with only one lensed image, the uncertainty is taken as 10% of the source-lens separation, which is typical for the scatter of individual sources in systems with multiple images (Shajib et al 2018;Schmidt et al 2023). The distribution of estimated Einstein radii is shown in Figure 15.…”