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Nov 14

AAA Lecture – Megamasers, Black Holes, and Cosmology

November 14, 2023 @ 7:00 PM - 8:30 PM EST

Join us for the first lecture in our 2023-24 AAA Lecture Series with speaker Jim Braatz of the National Radio Astronomy Observatory. The topic will be: Megamasers, Black Holes, and Cosmology

The Amateur Astronomers Association Lecture Series is held on the second Tuesday of each month, from October–May, beginning at 7:00 PM Eastern time.

Lectures are free and open to the public, but registration via Zoom is required.

In this lecture, Dr. Braatz will discuss observations and analysis of the accretion disks in orbit around supermassive black holes in galaxies.  We observe these disks with radio observations of water molecules within the disks, emitting as masers. We can use these observations to measure useful astrophysical properties including the orientation of the accretion disk and the mass of the black hole.  In some cases, we can use the masers to measure the distance to the host galaxy and get a direct measurement of the expansion rate of the universe: the Hubble Constant.  We will discuss the importance of modern measurements of the Hubble Constant, where mounting evidence shows that direct measurements of the value are in contradiction to the that predicted by the Standard Model of Cosmology.  Something in basic physics is amiss!


Dr. Braatz works at the National Radio Astronomy Observatory (NRAO)in the North American ALMA Science Center. This group supports the science done with the Atacama Large Millimeter/submillimeter Array (ALMA). He is the NRAO Student Program Coordinator responsible for summer programs and internships, Student Observing Support programs, doctoral fellows and co-ops.

His research is on radio emissions, mainly masers, from active galaxies. He is the Principal Investigator of the Megamaser Cosmology Project, an effort to measure the Hubble constant using geometrically determined distances to megamaser galaxies. This helps to understand the nature of dark energy which causes expansion of the universe to accelerate.

Dr. Braatz recently gave an AAA course on Multiwavelength and Radio Astronomy. He obtained a PhD in astronomy from the University of Maryland.


November 14, 2023
7:00 PM - 8:30 PM EST
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