IPM Calendar 
Thursday 28 March 2024   Today  
Events for day: Tuesday 11 August 2020    
           14:00 - 15:00     Weekly Seminar
HEPCo Group
Dynamical Tidal Locking Theory: A new source of the Spin of Dark Matter Halos

School
PHYSICS

Abstract:
We revisit the question of what mechanism is responsible for the spins of halos of dark matter. The answer to this question is of high importance for modeling galaxy intrinsic alignment, which can potentially contaminate current and future lensing data. In particular, we show that when the dark matter halos pass nearly by each other in dense environments-- namely halo assemblies-- they swing and spin each other via exerting mutual tidal torques. We show that this has a significant contribution to the spin of dark matter halos comparable to that of calculated by the so-called tidal torque theory (TTT). We use the results of st ...

           17:30 - 19:30     Geometry and Topology Seminar
An introduction to Lyapunov exponents

School
MATHEMATICS

The stability theorem of Lyapunov asserts that, under an additional regularity condition, the stability of the trivial solution of a linear equation remains valid for nonlinear perturbations. The regularity condition of Lyapunov essentially means that a certain limits exist. Such limits are called characteristic exponents or Lyapunov exponents.
In this talk we are going to introduce the concept of linear cocycles, and present the theorem of Furstenberg-Kesten which guarantees the existence of (extremal) Lyapunov exponents. Moreover, we are going to present the multiplicative ergodic theorem of Oseledets, and introduce some results re ...