Core Mass Estimates in Strong Lensing Galaxy Clusters Using a
  Single-Halo Lens Model
  The core mass of galaxy clusters is an important probe of structure
formation. Here, we evaluate the use of a Single-Halo model (SHM) as an
efficient method to estimate the strong lensing cluster core mass, testing it
with ray-traced images from the `Outer Rim' simulation. Unlike detailed lens
models, the SHM represents the cluster mass distribution with a single halo and
can be automatically generated from the measured lensing constraints. We find
that the projected core mass estimated with this method, M$_{\rm SHM}$, has a
scatter of $8.52\%$ and a bias of $0.90\%$ compared to the "true" mass within
the same aperture. Our analysis shows no systematic correlation between the
scatter or bias and the lens-source system properties. The bias and scatter can
be reduced to $3.26\%$ and $0.34\%$, respectively, by excluding models that
fail a visual inspection test. We find that the SHM success depends on the
lensing geometry, with single giant arc configurations accounting for most of
the failed cases due to their limiting constraining power. When excluding such
cases, we measure a scatter and bias of $3.88\%$ and $0.84\%$, respectively.
Finally, we find that when the source redshift is unknown, the model-predicted
redshifts are overestimated, and the M$_{\rm SHM}$ is underestimated by a few
percent, highlighting the importance of securing spectroscopic redshifts of
background sources. Our analysis provides a quantitative characterization of
M$_{\rm SHM}$, enabling its efficient use as a tool to estimate the strong
lensing cluster core masses in the large samples, expected from current and
future surveys.
