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Register a new userJoint Strong and Weak Lensing Analysis of the Massive Cluster Field J0850+3604
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Kenneth C. Wong
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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 galaxys 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.
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We present a gravitational lensing model of MACS J1149.5+2223 using ultra-deep Hubble Frontier Fields imaging data and spectroscopic redshifts from HST grism and VLT/MUSE spectroscopic data. We create total mass maps using 38 multiple images (13 sources) and 608 weak lensing galaxies, as well as 100 multiple images of 31 star-forming regions in the galaxy that hosts Supernova Refsdal. We find good agreement with a range of recent models within the HST field of view. We present a map of the ratio of projected stellar mass to total mass ($f_{star}$), and find that the stellar mass fraction for this cluster peaks on the primary BCG. Averaging within a radius of 0.3 Mpc, we obtain a value of $langle f_{star} rangle = 0.012^{+0.004}_{-0.003}$, consistent with other recent results for this ratio in cluster environments, though with a large global error (up to $delta f_{star} = 0.005$) primarily due to the choice of an IMF. We compare values of $f_{star}$ and measures of star formation efficiency for this cluster to other Hubble Frontier Fields clusters studied in the literature, finding that MACS1149 has a higher stellar mass fraction than these other clusters, but a star formation efficiency typical of massive clusters.
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