Department of Astronomy & Astrophysics
University of Chicago
Thursday, January 24th 2019, 18:30
Stephen Leacock Building, Leacock Auditorium (room 132)
New Windows on the Cosmos
For over 400 years, astronomers have used telescopes to study the universe.
Technological advances have led to four centuries of remarkable astronomical
discoveries. In the last few decades alone, we have discovered about thousands
of new planets outside of those in our own Solar System, observed galaxies
colliding and merging out to tremendous distances, and observed the entire
universe to be expanding at an increasing rate, pulled apart by a cosmic force,
unexplained by any of our current physical theories. Astronomers have ambitious
plans for this new millennium - with giant new telescopes planned for both the
ground and space. Dr. Freedman will focus on recent astronomical discoveries,
and show how new facilities being built on Earth will address some of the
biggest mysteries in astronomy today.
Friday, January 25th 2019, 15:30
Ernest Rutherford Physics Building, Keys Auditorium (room 112)
Tension in the Hubble Constant
Currently there is a significant discrepancy between measures of the Hubble
constant obtained from modeling Planck observations of the cosmic microwave
background, and those from direct local measurements. I will describe new
results from a decade-long project to measure the Hubble constant to higher
precision and accuracy, the Carnegie-Chicago Hubble Program. This program
utilizes the resolution of the Hubble Space Telescope, the long-wavelength
reach of Spitzer, the capability of ground-based telescope with a range of
aperture sizes, including automated follow-up telescopes, to provide new
and independent data for the measurement of extragalactic distances. The CCHP
project was initiated in anticipation of the launch of ESA's Gaia satellite. The
goal of the program is to reduce systematic errors in the distance scale. A
robust determination of the overall systematic uncertainties in Ho can only
be achieved using several independent methods. This program includes Cepheids
and tip of the red giant branch (TRGB) stars, and Type Ia supernovae, the
latter as part of the Carnegie Supernova Project (CSP). For the first time
ever, we have an approach as accurate as the Cepheids for the calibration of
the extragalactic distance scale
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