Prof. Patrick Kelly

CSENG Physics & Astronomy
College of Science & Engineering
Twin Cities
Project Title: 
Understanding the Observed Rate of Microlensing Events of High-Redshift Stars

These researchers have recently detected five individual highly magnified stars in Hubble Space Telescope (HST) imaging at look-back times of approximately half the age of the universe. These stars are located behind massive foreground galaxy clusters whose gravitationally lensing power magnifies them, on average, by factors of hundreds. When a foreground object in the galaxy cluster such as a star or remnant becomes temporarily aligned, the stars can become magnified by factors of many thousands. The observed rate of such magnification peaks significantly exceeds the expected rate, and this group has developed a full model to interpret the high rate. Explanations could include the existence of a population of primordial black holes formed after the Big Bang or a different population of high luminosity stars at earlier epochs in the universe. The group uses MSI resources to explore the possible interpretations.

Project Investigators

Prof. Patrick Kelly
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