Automated galaxy-galaxy strong lens modelling: no lens left behind
  The distribution of dark and luminous matter can be mapped around galaxies
that gravitationally lens background objects into arcs or Einstein rings. New
surveys will soon observe hundreds of thousands of galaxy lenses, and current,
labour-intensive analysis methods will not scale up to this challenge. We
instead develop a fully automatic, Bayesian method which we use to fit a sample
of 59 lenses imaged by the Hubble Space Telescope in uniform conditions. We set
out to \textit{leave no lens behind} and focus on ways in which automated fits
fail in a small handful of lenses, describing adjustments to the pipeline that
allows us to infer accurate lens models. Our pipeline ultimately fits {\em all}
59 lenses in our sample, with a high success rate key because catastrophic
outliers would bias large samples with small statistical errors. Machine
Learning techniques might further improve the two most difficult steps:
subtracting foreground lens light and initialising a first, approximate lens
model. After that, increasing model complexity is straightforward. We find a
mean $\sim1\%$ measurement precision on the measurement of the Einstein radius
across the lens sample which {\em does not degrade with redshift} up to at
least $z=0.7$ -- in stark contrast to other techniques used to study galaxy
evolution, like stellar dynamics. Our \texttt{PyAutoLens} software is open
source, and is also installed in the Science Data Centres of the ESA Euclid
mission.
