TY  - GEN
A1  - Nishikawa, Ken-Ichi
A1  - Mizuno, Yosuke
A1  - Niemiec, Jacek
A1  - Kobzar, Oleh
A1  - Pohl, Martin
A1  - Gómez, Jose L.
A1  - Duţan, Ioana
A1  - Pe’er, Asaf
A1  - Frederiksen, Jacob Trier
A1  - Nordlund, Åke
A1  - Meli, Athina
A1  - Sol, Helene
A1  - Hardee, Philip E.
A1  - Hartmann, Dieter H.
T1  - Microscopic processes in global relativistic jets containing helical magnetic fields
T2  - Galaxies
N2  - In the study of relativistic jets one of the key open questions is their interaction with the environment on the microscopic level. Here, we study the initial evolution of both electron-proton (e(-)-p(+)) and electron-positron (e(+/-)) relativistic jets containing helical magnetic fields, focusing on their interaction with an ambient plasma. We have performed simulations of "global" jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability (kKHI) and the Mushroom instability (MI). In our initial simulation study these kinetic instabilities are suppressed and new types of instabilities can grow. In the e(-)-p(+) jet simulation a recollimation-like instability occurs and jet electrons are strongly perturbed. In the e(+/-) jet simulation a recollimation-like instability occurs at early times followed by a kinetic instability and the general structure is similar to a simulation without helical magnetic field. Simulations using much larger systems are required in order to thoroughly follow the evolution of global jets containing helical magnetic fields.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 446 
KW  - relativistic jets
KW  - particle-in-cell simulations
KW  - global jets
KW  - helical magnetic fields
KW  - kinetic instabilities
KW  - kink instability
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-407604
ER  - 
TY  - GEN
A1  - Nishikawa, K.-I.
A1  - Zhang, B.
A1  - Choi, E. J.
A1  - Min, K. W.
A1  - Niemiec, J.
A1  - Medvedev, M.
A1  - Hardee, P.
A1  - Mizuno, Y.
A1  - Nordlund, A.
A1  - Frederiksen, J.
A1  - Sol, H.
A1  - Pohl, Martin
A1  - Hartmann, D. H.
A1  - Fishman, G.J.
T1  - Radiation from accelerated particles in shocks
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs in the shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and for particle acceleration. These magnetic fields contribute to the electron’s transverse eflection behind the shock. The “jitter” radiation from deflected electrons in turbulent magnetic fields has properties different from synchrotron radiation calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure of gamma-ray bursts, relativistic jets in general, and supernova remnants. In order to calculate radiation from first principles and go beyond the standard synchrotron model, we have used PIC simulations. We present synthetic spectra to compare with the spectra obtained from Fermi observations.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 600 
KW  - relativistic jets
KW  - Weibel instability
KW  - magnetic field generation
KW  - particle acceleration
KW  - radiation
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-413128
SN  - 1866-8372
IS  - 600
SP  - 371
EP  - 372
ER  -