Joint Strong and Weak Lensing Analysis of the Massive Cluster Field
  J0850+3604
  We present a combined strong and weak lensing analysis of the
J085007.6+360428 (J0850) field, which was selected by its high projected
concentration of luminous red galaxies and contains the massive cluster Zwicky
1953. Using Subaru/Suprime-Cam $BVR_{c}I_{c}i^{\prime}z^{\prime}$ imaging and
MMT/Hectospec spectroscopy, we first perform a weak lensing shear analysis to
constrain the mass distribution in this field, including the cluster at $z =
0.3774$ and a smaller foreground halo at $z = 0.2713$. We then add a strong
lensing constraint from a multiply-imaged galaxy in the imaging data with a
photometric redshift of $z \approx 5.03$. Unlike previous cluster-scale lens
analyses, our technique accounts for the full three-dimensional mass structure
in the beam, including galaxies along the line of sight. In contrast with past
cluster analyses that use only lensed image positions as constraints, we use
the full surface brightness distribution of the images. This method predicts
that the source galaxy crosses a lensing caustic such that one image is a
highly-magnified "fold arc", which could be used to probe the source galaxy's
structure at ultra-high spatial resolution ($< 30$ pc). We calculate the mass
of the primary cluster to be $\mathrm{M_{vir}} = 2.93_{-0.65}^{+0.71} \times
10^{15}~\mathrm{M_{\odot}}$ with a concentration of $\mathrm{c_{vir}} =
3.46_{-0.59}^{+0.70}$, consistent with the mass-concentration relation of
massive clusters at a similar redshift. The large mass of this cluster makes
J0850 an excellent field for leveraging lensing magnification to search for
high-redshift galaxies, competitive with and complementary to that of
well-studied clusters such as the HST Frontier Fields.
