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Feb 5 2020

Physics Colloquium: Tension in the Hubble Constant

February 5, 2020

3:00 PM - 4:00 AM


SES 238


901 W. Taylor St., Chicago, IL 60607

Click here for more information

Speaker: Wendy Freedman, University of Chicago

Tension in the Hubble Constant

There has arisen a tension in the value of the Hubble constant measured locally (based on Cepheids and Type Ia supernovae) with that inferred from measurements of the cosmic background radiation, assuming the standard cosmological model. I will present new results from the Carnegie-Chicago Hubble Program (CCHP), the goal of which is to independently measure a value of the Hubble constant to very high precision and accuracy. We have built an entirely new extragalactic distance scale using tip of the red giant branch (TRGB), based on observations with the Hubble Space Telescope Advanced Camera for Surveys. Our supernova sample comes from the Carnegie Supernova Project, carried out at Las Campanas, Chile. Our value of the Hubble constant,  Ho = 69.8, with statistical and systematic uncertainties of 0.8 and 1.7 km/sec/Mpc, respectively, falls midway between the value obtained from the Planck Cosmic Microwave Background analysis, and that obtained using Cepheids.  I will  address the uncertainties, andthe discuss the current tension in Ho.


Physics Officer

Date posted

Jan 23, 2020

Date updated

Jan 23, 2020