[Okc-wp4] EO Meeting on Feb 7 (note the slight change in schedule)

[Andre Schneider]

Dear all,


our first EO meeting of 2019 will be this Thursday Feb 7 from 13:15 to 14:00 (KTH meeting room on the 5th floor).

Joonas Nättilä will give the following talk:


Title: Magnetically-dominated collisionless plasma flows in neutron star atmospheres

Abstract: I will discuss collisionless plasma instabilities operating on magnetically-dominated flows in neutron star atmospheres. We define a criteria for out-of-resonance two-stream instability to be operational in the stratified atmosphere. Our theoretical findings are then confirmed with high-resolution, first-principles relativistic Vlasov-Maxwell simulations. This allows us to study the subsequent non-linear turbulent evolution of the system. We find a new plasma mechanism that reprocesses the incoming mildly-relativistic beams: The incoming beams are slowed down, heated up, but not brought to full halt either. Ultra-relativistic beams are still capable of penetrating into the star unaffected. This implies that diluted free-falling accretion flows into neutron stars are always reprocessed in the uppermost layers of the star's atmosphere before entering the particle-collision-dominated layers below. This beam-atmosphere interaction is also responsible of heating the corona. The reprocessing of the beam leads to a turbulent atmospheric layer where outward moving double layers are being excited. These uprising particle-acceleration sites are similar to earthly auroras, and are a possible new source of non-thermal X-ray radiation from neutron stars.


See you there!



---------------------------------

André da Silva Schneider

Department of Astronomy

Stockholm University


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