University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, February 24th 2017
Speaker: Patrick Kelly, University of California - Berkeley
Subject: Using Galaxy Cluster Lenses as Extreme Probes
Candidate for the MIfA Assistant Professor position

Galaxy clusters can highly magnify galaxies behind them, making cluster lenses powerful tools for studying the high-redshift universe. The James Webb Space Telescope, when pointed towards foreground cluster fields, will be sensitive to even low-luminosity galaxies at redshift z > 6 (~35th magnitude) thought to drive reionization. In regions of high magnification, however, cluster magnification maps show strong disagreements. I will describe the first-known multiply imaged, strongly lensed supernova (SN), which appeared in late 2014 in an Einstein cross configuration in the MACS1149 galaxy-cluster field. The timing of the reappearance of the SN, at an offset of ~8 arcseconds, in 2015 disagrees with most but not all predictions, and illustrates a promising approach for identifying the most accurate cluster-modeling techniques and magnification maps. I will next discuss observations of an individual star at high redshift, which acts as a new window into the nature of galaxy-cluster dark matter. Detections of hundreds of thousands of SNe and thousands of lensed transients by the Large Synoptic Survey Telescope and the Wide-Field Infrared Survey Telescope will allow new insights into star formation and stellar evolution beginning at z~15-20, as well as the nature of dark matter and dark energy.

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