Physics Colloquium: Stepping into the light with high power lasers and brilliant gamma beams

Prof. Sydney Gales, IPN Orsay

28 April 2019, 14:00 
Shenkar Building, Melamed Hall 006 
Physics Colloquium

The Emilio Segre Distinguished Lectures in Physics of the Raymond and Beverly Sackler Foundation

Professor Judah M. Eisenberg Memorial Lecture

 

Abstract:

The Center of our Galaxy is a unique laboratory for exploring the astrophysics around a massive black hole and testing General Relativity in this extreme environment. I will discuss the results of a major campaign of observing the Galactic Center in 2017/2018 with three instruments at the European Southern Observatory's VLT, including the novel GRAVITY interferometric beam combiner of the four 8-meter telescopes. During this period the B-star S2 completed a peri-passage at ~1400 Schwarzschild radii around the compact radio source SgrA*, and permitted for the first time a test of the equivalence principle and the detection of the first post-Newtonian orbital elements in a classical 'clock experiment' around a massive black hole. During bright states ("flares") we detect centroid motions and polarization changes of the infrared emission of SgrA* itself. These can be well fitted by near face-on, circular orbits near the innermost circular orbit (ISCO). The mass inferred at ISCO is the same as that within the S2 orbit, further strengthening the evidence that SgrA* is a Kerr black hole.

 

I will conclude by summarizing some of the extragalactic results with GRAVITY and the possibility for future upgrades of optical interferometry.

 

 

Event Organizer: Dr. Ishay Pomerantz

Tel Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel
UI/UX Basch_Interactive