Kyle Finner (Yonsei University) -- HST Infrared Weak-lensing Analysis of the Emerging Galaxy Cluster SpARCSJ1049+56 at z=1.71


The mass of galaxy clusters covering a large range of redshifts is an excellent probe for studying cosmology and the growth of structure in the universe. Weak gravitational lensing is a robust method to measure the mass of galaxy clusters. However, very few weak-lensing studies of galaxy clusters have been achieved at redshifts greater than unity. Furthermore, galaxy clusters at high redshift offer a unique look into their formation and evolution because they are expected to be actively forming and dynamically young. SpARCSj1049+56 is a galaxy cluster located at a redshift of 1.71 that has been shown to have intense star formation of ~900 Msun/yr. At such high redshift, a weak-lensing analysis is pushed from the optical regime into the infrared. Utilizing deep Hubble Space Telescope WFC3 UVIS and IR observations, we achieved a weak-lensing characterization of SpARCSJ1049+56. As few IR weak-lensing studies have been performed, I will discuss the details of point spread function modeling and galaxy shape measurement for an IR weak-lensing procedure and the systematics that come with the territory. I will present the results of our weak-lensing analysis and discuss the implications for galaxy cluster evolution and cosmology. In addition, I will discuss our Chandra X-ray discovery of runaway gas cooling that may be fueling the burst of star formation.