Astronomy Colloquium Speaker Calendar

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Astronomy Colloquium - "Engineering a Modern Distance Ladder for Modern Challenges"

Event Type
Seminar/Symposium
Sponsor
Astronomy Department
Location
Astronomy 134
Date
Sep 26, 2019   3:45 pm  
Speaker
Rachael Beaton, Princeton University
Contact
Rebecca Bare
E-Mail
rsbare@illinois.edu
Phone
217-333-3090
Views
56

Measurements in the early 21st century brought cosmology into its an age of concordance, but this was not to last. Today we face a ~4-sigma tension between the two modern measurement techniques: the traditional Cepheid-based distance ladder and model-fitting of the Cosmic Microwave Background. The resolution of this tension is either (i) uncovering heretofore unaccounted for systematics or (ii)  “new physics” that is currently absent from the standard, 6-parameter, Lambda-cold dark matter model. I will use backward design to motivate the fundamental limitations of the traditional distance-ladder based on Cepheids and explain how the unparalleled trigonometric datasets from Gaia give us the first real opportunity to build an alternate path to calibrate Type Ia Supernova -- our workhorse tool to constrain the expansion history of the Universe. I will walk through how the Carnegie-Chicago Hubble Program has realized a competitive calibration of the Type Ia Supernova using the tip of the red giant branch as a standard candle. I will further demonstrate how the TRGB employed in the near-infrared with future instrumentation could be used to transform fundamentally how we measure the Hubble Constant. I will describe the current challenges for the realization of this goal and my on-going plan for tackling these, and other limitations of the current distance scale.

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