Speaker
Kevin Michael Schoeffler
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O4.405.pdf
Triggering QED processes by reconnection in near critical magnetic fields
K. M. Schoeffler1 , T. Grismayer1 , D. A. Uzdensky2 , R. A. Fonseca1,3 ,L O. Silva1
1 GoLP/Instituto de Plasmas e Fusão Nuclear,
Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal,
2 Center for Integrated Plasma Studies, Physics Department,
University of Colorado, Boulder CO 80309, USA
3 DCTI/ISCTE Instituto Universitário de Lisboa, 1649-026 Lisboa, Portugal
Magnetic reconnection is a process that is known to violently release energy from magnetic
fields in events such as solar flares, geomagnetic storms, and flares found in various astrophysi-
cal objects. In the most extreme magnetic fields found in magnetars, and pulsar magnetospheres,
the magnetic fields reach the critical quantum (Schwinger) field BQ ≡ m2e c3 /eh̄ ≃ 4.4 × 1013 G,
where various QED processes play an important role [2].
We investigate the effects of QED radiation and pair-creation in the presence of strong mag-
netic fields on magnetic reconnection starting with a relativistic pair plasma using both 2D and
3D particle-in-cell simulations. The simulations are performed with the QED module [1] of the
OSIRIS framework that includes single photon emission by electrons and positrons (non-linear
Compton scattering) and single photon decay into pairs (non-linear Breit-Wheeler). We show
that even when the magnetic fields initially do not exhibit QED effects, the reconnection leads
to both energetic particles, and enhanced magnetic fields, such that radiative cooling and pair-
production processes begin to play an important role. We highlight that the radiation spectra
that may be observable from such events differs strongly from the classical cases with much
steeper spectra. This study is a first concrete step towards better understanding of magnetic re-
connection as a possible mechanism powering gamma-ray flares in magnetar magnetospheres.
References
[1] T. Grismayer et al., Physics of Plasmas 23, 056706 (2016)
[2] D.A. Uzdensky, Space Science Reviews 160, 45-71 (2011)
