Department of Physics
Research, teaching and outreach in Physics at UW–Madison

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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Probing The Impact of Cluster Weak Lensing Bias On DES Y1 Cluster Cosmological Results
Date: Friday, May 12th
Time: 12:00 pm - 1:00 pm
Place: Chamberlin 5280
Speaker: Johnny Esteves, University of Michigan
Abstract: Over the last two decades of large photometric surveys, optical cluster cosmology has presented a promising way to improve cosmological measurements and our current understanding of dark matter and dark energy. The Dark Energy Survey (DES) Y1 cluster's analysis has revealed a new systematic effect that affects weak lensing measurements, called weak lensing bias. The weak lensing bias arises from the correlation between the mass proxy (such as richness or λ) and the lensing profile for a given mass. The effect is mainly caused by the presence of projected red galaxies along the line of sight, which can bias the mass estimate. However, how this systematic effect impacted the Y1 cosmology is still unclear.

In this talk, I will present a novel forward modeling methodology that was developed specifically for Y3 and outline the technical computing challenges involved in solving multi-dimensional integrals. These challenges have been overcome by utilizing graphics processing units (GPUs), which provide exceptional computational speed and accuracy. In addition, I will present my work on the commissioning of the Rubin Observatory, which will provide invaluable data for advancing our cosmological understanding of the Universe.
Host: Keith Bechtol
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