Abstract:  I will discuss two of our most precise methods for measuring distances in the local universe: Cepheids and the Tip of the Red Giant Branch (TRGB). 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 a precision and accuracy of 2%. Using the Hubble Space Telescope Advanced Camera for Surveys,  we are  using the TRGB to calibrate Type Ia supernovae. Our value of the Hubble constant, Ho = 69.6 +/- 0.8 (statistical) +/- 1.7 (systematic) km/sec/Mpc, falls midway between the value obtained from the Planck Cosmic Microwave Background analysis, and that obtained using Cepheids. I will address the uncertainties, discuss the current tension in Ho, and whether there is need for additional physics beyond the standard CDM model.

Host:  Stephanie Wissel

Astro Colloquium and 'coffee & cookies' Department gathering (3:30-4:00pm)

https://psu.zoom.us/j/94153970341