Colloquium on Nov. 12, 2020

New Theoretical Insights into the Nonthermal Sky Based on Observations of Very-High-Energy Particles

Speaker: Takahiro Sudoh (University of Tokyo)

Venue: Video Conference

Time: 15:00 PM, Thursday, Nov. 12, 2020

Abstract:

It is widely believed that supernova remnants are the most important sources for the galactic nonthermal emission. However, many observations cannot be accounted for within this framework. In the TeV gamma rays, the origin of diffuse emission from the Galactic disk and the nature of many sources in the Galaxy have not been clear. In the radio band, recent observations suggest a peculiar excess emission in galaxies with low star-formation rates. In this talk, I will discuss the importance of pulsars for these problems. In particular, we focus on the implications from the observations of “TeV halos”, a source class which is recently discovered around nearby pulsars. We show that pulsar emission can dominate the TeV gamma-ray sky, explaining the majority of diffuse emission as well as source counts. Then, we show that recycled/millisecond pulsars can significantly contribute to the galactic nonthermal emission, explaining the radio excess. We discuss the implications for the studies of cosmic rays, gamma rays, and pulsars.

Report PPT:  SWIFAR_Takahiro Sudoh.pdf