Colloquium: Dr. Kailash Sahu, Space Telescope Science Inst.
Wednesday, November 13, 2019 · 3:30 PM - 4:30 PM
TITLE: Study of White Dwarfs and Black Holes through Relativistic Bending of Light
In a reprise of the famous 1919 solar eclipse experiment that confirmed
Einstein's general relativity, the nearby white dwarf Stein 2051B passed very
close to a background star in March 2014. As Stein 2051B passed by, the
background star's position was relativistically deflected. Measurement of this
deflection with the Hubble Space Telescope (HST) allowed us to determine the
mass of Stein 2051B, which confirms the physics of degenerate matter and
provides a new tool for mass determinations of isolated stars. Another consequence of the relativistic bending of light is the temporary
brightening of the background star, commonly known as gravitational microlensing. The combination of brightening and deflection provides a powerful technique to detect isolated black holes, and measure their masses. I will discuss the technique, and our HST programs aimed at the first detections of stellar-mass black holes through this technique.