BHI Colloquium | March 7: Burkhard Schwab, Jeff Oishi скачать в хорошем качестве

BHI Colloquium | March 7: Burkhard Schwab, Jeff Oishi

Burkhard Schwab Harvard University Abstract: Conservation laws can be very powerful tools for the analytical calculation of interesting quantities. In this talk, I will show that the absorption rate of low-energy -- or soft -- electromagnetic radiation by spherically symmetric black holes in D dimensions can be completely fixed by conservation statements. Jeff Oishi Bates College Abstract: The accretion of material onto compact objects, including black holes and neutron stars is the most efficient way to turn mass into energy. It is thought to be responsible for powering the most luminous sources in the night sky. Additionally, the disks of material accreting onto forming protostars play host to the formation of planets. In this talk, I will focus on one proposed mechanism for astrophysical accretion, the magnetorotational instability (MRI). In particular, I will focus on the dynamics of the instability in the limit when the non-linearities are weak. The MRI can be studied in the context of pattern formation, in which non-linear terms lead to the spontaneous selection of certain spatial features. Understanding these features allow us to probe the physical mechanism responsible for the saturation of the instability. In turn, this will allow us to understand the behavior of the MRI in the extreme parameter regimes inaccessible to simulation but realized in astrophysical systems.