TOK-Seminar 2024




Electrospheres and (e+,e-) pair plasmas

TOK Seminar
The magnetosphere of neutron stars is, as far as we know, one of the very few examples where an electron-positron plasma is formed. When the plasma reaches a stable state, the strong fields around a neutron star probably lead to a complete charge separation. Such a purely non-neutral plasma is an exception compared to the quasineutral state that most of our visible universe is in. Finding self consistent models for the evolution and distribution of theses plasmas is an active field of research. Understanding the instibilities of such a system might help understand astrophysical phenomena such as fast radio bursts. [mehr]

Positron annihilation as an astrophysical messenger

TOK Seminar
One of the major tasks of astrophysics is to understand the emission mechanisms of observed sources and regions in the sky. Only by pinpointing down these mechanisms, it is possible to derive physical parameters and learn about the evolution of astrophysical objects. Alas, many observations of high-energy phenomena are ambiguous, requiring more and orthogonal information. The nature of several sources, among others accreting X-ray binary systems, core-collapse and thermonuclear supernovae, cosmic-rays, stellar flares and potentially dark matter, all show signatures of positron production and annihilation. Utilising this underrated emission mechanism can shed light on unsolved problems in astrophysics and cosmology. [mehr]
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