RADIATION SIGNATURES OF SUB-LARMOR SCALE MAGNETIC FIELDS / Medvedev Mikhail V.,Frederiksen Jacob Trier,Haugbolle Troels,Nordlund Ake // ASTROPHYSICAL JOURNAL. - 2011. - V. 737, l. 2.

ISSN/EISSN:

0004-637X / нет данных

Type:

Article

Abstract:

Spontaneous rapid growth of strong magnetic fields is rather ubiquitous in high-energy density environments ranging from astrophysical sources (e.g., gamma-ray bursts and relativistic shocks), to reconnection, to laser-plasma interaction laboratory experiments, where they are produced by kinetic streaming instabilities of the Weibel type. Relativistic electrons propagating through these sub-Larmor-scale magnetic fields radiate in the jitter regime, in which the anisotropy of the magnetic fields and the particle distribution have a strong effect on the produced radiation. Here we develop the general theory of jitter radiation, which (1) includes anisotropic magnetic fields and electron velocity distributions, (2) accounts for the effects of trapped electrons, and (3) extends the description to large deflection angles of radiating particles thus establishing a cross-over between the classical jitter and synchrotron regimes. Our results are in remarkable agreement with the radiation spectra obtained from particle-in-cell simulations of the classical Weibel instability. Particularly interesting is the onset of the field growth, when the transient hard synchrotron-violating spectra are common as a result of the dominant role of the trapped population. This effect can serve as a distinct observational signature of the violent field growth in astrophysical sources and lab experiments. It is also interesting that a system with small-scale fields tends to evolve toward the small-angle jitter regime, which can, under certain conditions, dominate the overall emission of a source.

Author keywords:

gamma-ray burst: general; magnetic fields; magnetic reconnection; plasmas; radiation mechanisms: non-thermal; shock waves RELATIVISTIC COLLISIONLESS SHOCKS; ELECTRON-ION PLASMAS; RAY BURST SOURCES; PARTICLE-ACCELERATION; WEIBEL INSTABILITY; JITTER RADIATION; SYNCHROTRON-RADIATION; SYNTHETIC SPECTRA; PROMPT EMISSION; COSMIC-RAYS

DOI:

10.1088/0004-637X/737/2/55

Web of Science ID:

ISI:000294013600009

Соавторы в МНС:

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Другие поля

Поле	Значение
Month	AUG 20
Publisher	IOP PUBLISHING LTD
Address	TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Language	English
Article-Number	55
Keywords-Plus	RELATIVISTIC COLLISIONLESS SHOCKS; ELECTRON-ION PLASMAS; RAY BURST SOURCES; PARTICLE-ACCELERATION; WEIBEL INSTABILITY; JITTER RADIATION; SYNCHROTRON-RADIATION; SYNTHETIC SPECTRA; PROMPT EMISSION; COSMIC-RAYS
Research-Areas	Astronomy \& Astrophysics
Web-of-Science-Categories	Astronomy \& Astrophysics
ResearcherID-Numbers	Nordlund, Aake/M-4528-2014 Frederiksen, Jacob Trier/P-6757-2015 Haugbolle, Troels/L-7984-2014
ORCID-Numbers	Nordlund, Aake/0000-0002-2219-0541 Frederiksen, Jacob Trier/0000-0002-3560-0044 Haugbolle, Troels/0000-0002-9422-8684
Funding-Acknowledgement	NSF {[}AST-0708213]; NASA ATFP {[}NNX-08AL39G]; DOE {[}DE-FG02-07ER54940]; Ambrose Monell Foundation (IAS); Ib Henriksen Foundation (NBIA)
Funding-Text	M. V. M. work has been supported by NSF grant AST-0708213, NASA ATFP grant NNX-08AL39G, and DOE grant DE-FG02-07ER54940. M. V. M. also acknowledges support from The Ambrose Monell Foundation (IAS) and The Ib Henriksen Foundation (NBIA). Computer time was provided by the Danish Center for Scientific Computing (DCSC).
Number-of-Cited-References	52
Usage-Count-Since-2013	5
Journal-ISO	Astrophys. J.
Doc-Delivery-Number	808WV