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Kramers-Kronig relation in gravitational lensing
11/03
2023
Seminar
- Title Kramers-Kronig relation in gravitational lensing
- Speaker Teruaki Suyama (Tokyo Institute of Technology)
- Date 2023年11月3日 10:00
- Venue 6620, South Building
Abstract
Gravitational lensing (GL) has been a powerful method to probe matter inhomogeneities in the Universe. GL of gravitational waves, which will be detected in the near future, will enable us to gain more information of the nature of dark matter and further boost the significance of GL. In light of this situation, it is important to have understanding of basic properties of GL. In my talk, I show that gravitational lensing obeys the causality in the sense that (electromagnetic/gravitational) waves emitted from the source arrive at an observer only after the arrival of the signal in geometrical optics. This leads to the Kramers-Kronig relation, a well-known relation in the field of optics, in GL, as the relation between real and imaginary parts of the amplification factor. I will also show some relations which hold as consequence of the Kramers-Kronig relation. Finally, I argue that examining the violation of the Kramers-Kronig relation may be used for correctly extracting the lensing signal in the gravitational wave observations.
Bio：
Dr. Teruaki Suyama is a Professor at Tokyo Institute of Technology, Japan. He received his PhD in Physics from Kyoto University in 2007. After spending at a few places such as the University of Tokyo and Louvain Catholic University as a postdoc, he became an assistant professor at Research Center for the Early Universe in 2012. He moved to the current place as an associate professor in 2018 and was promoted to a professor in 2023. He has worked on various topics on cosmology to elucidate the earliest moments of and the evolution of our universe. His current interest is to understand what kind of new information about our universe can be gained by using gravitational waves.
Invitor:
Shi Pi