University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, March 15th 2019
2:30 pm:
Speaker: Emil Rivera-Thorsen, University of Oslo
Subject: A Series Of Fortunate Events: The discovery of a unique, lensed Lyman-continuum leaking galaxy at z=2

"The brightest known gravitationally lensed galaxy is arguably also among the most interesting.
Discovered as part of the Planck Foreground Project and included in the Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas (MEGaSaURA), it is a young, dusty, and very bright starburst at z=2.4. Due to a fortunate alignment of lensing cluster galaxies, it is found in no less than 12 image-plane copies along four major arc segments. A theoretically predicted, but not previously observed, triple-peaked Lyman-alpha emission line profile has revealed that a narrow, empty channel through the neutral medium is aligned with the line-of-sight to Earth, giving us a so far unique, direct view at the young OB stars in the galaxy's most luminous cluster complex. The clear line of sight to the young star clusters has allowed the brightest and best resolved detection of escaping, ionizing Lyman-continuum radiation yet observed at redshifts beyond 0.5, even rivaling some of the local-Universe detections in brightness. The lines of sight traced by the multiply imaged ionizing radiation also provides a direct probe into intergalactic HI on transverse scales at least an order of magnitude smaller than so far probed by close quasar pairs.
In this talk, I will present our findings so far, discuss some of the implications for our knowledge of the radiative transfer and escape of Lyman-alpha and ionizing photons, and show some further puzzling aspects of the galaxy and how they may point us to further research."

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