[NCTS Astrophysics Lunch Seminar] Satellite-Magnetosphere Interactions at Outer Planets & Linear Instability Analysis of collective neutrino oscillation under turbulent media fluctuation

Time:2024/03/01 (Fri.) 12:10-13:10
Place:4F Lecture Hall, Cosmology Hall, NTU

Title:Satellite-Magnetosphere Interactions at Outer Planets
Speaker:Pei-Chun Tsai (NCU)
The interaction between satellites and magnetospheres plays an important role in the magnetospheres of the outer planets. One of the most intriguing phenomena is the radiolysis effects observed on Saturnian icy moons, Mimas and Tethys. These effects have drawn significant attention due to its Pac-man like patterns of surface temperature distribution. The unique leading-side/trailing-side asymmetries on the surface ice layers of Mimas and Tethys result from the bombardment process of the energetic electrons that are trapped within Saturn’s nearly symmetrical dipole field. Considering this, it becomes interesting to determine if similar radiolysis effects might still be observed on the  icy moons of Uranus and Neptune. These moons possess highly asymmetric magnetic fields, with their magnetic axis being highly tilted and displaced. This research will employ the simplified Offset-Tilted Dipole (OTD) models for Uranus, and multiple numerical models to trace the trajectories of energetic particles, such as ions and electrons with different energies, aiming to understand particle impact flux distributions on these satellite surfaces and the subsequent radiation micro-absorption signatures.
Keywords: Uranus, Miranda, Offset-Tilted Dipole (OTD), charged particles

Title:Linear Instability Analysis of collective neutrino oscillation under turbulent media fluctuation
Speaker:Heng-Hao Chen (NTHU)
Linear instability analysis is one of the ways to understand whether collective neutrino oscillations may occur in dense environments inside core-collapse supernovae. A literature (arXiv:2007.13655) proposed that the instabilities at the higher wavenumber (k-) modes due to the presence of turbulence would “leak” to lower modes thus making instabilities ubiquitous from small to large scales in the system. In this work we explore such a system in further detail. Our results show that the instability growth rates of a turbulent-coupled system are nearly identical to the non-turbulent one in the linear regime although k-modes are indeed coupled. As a result, the evolution of the system in z with the turbulent-coupled effect is similar to the non-coupled systems at smaller z. The “leakage” effect only takes place when the system later transitions into the non-linear regime.

*registration will be closed at 02/27(Tue.)12:00 noon.