Crab nebula gamma-ray flares as relativistic reconnection minijets

被引：54

作者：

Clausen-Brown, E. ^{[1
]}

Lyutikov, M. ^{[1
]}

机构：

[1] Purdue Univ, Dept Phys, 525 Northwestern Ave, W Lafayette, IN 47907 USA

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2012年 / 426卷 / 02期

关键词：

magnetic reconnection - MHD; radiation mechanisms: non-thermal; pulsars: general; ISM: individual objects: Crab nebula; ISM: jets and outflows; PARTICLE-ACCELERATION; MAGNETIC-FIELD; EMISSION; PULSAR; JETS; VARIABILITY; SHOCKS; MODEL; WINDS; TELESCOPE;

D O I：

10.1111/j.1365-2966.2012.21349.x

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The unusually short durations, high luminosities and high photon energies of the Crab nebula gamma-ray flares require the relativistic bulk motion of the emitting plasma. We explain the Crab flares as a result of randomly oriented relativistic minijets originating from reconnection events in a magnetically dominated plasma. We develop a statistical model of the emission from Doppler boosted reconnection minijets and find analytical expressions for the moments of the resulting nebula light curve (e.g. time average, variance, skewness). The light curve has a flat power spectrum that transitions at short time-scales to a decreasing power law of index 2. The flux distribution from minijets follows a decreasing power law of index similar to 1, implying that the average flux from flares is dominated by bright rare events. The predictions for the flares statistics can be tested against forthcoming observations. We find that the observed flare spectral energy distributions (SEDs) have several notable features: a hard power-law index of p ? 1 for accelerated particles that is expected in various reconnection models, including some evidence of a pile-up near the radiation reaction limit. Also, the photon energy at which the SED peaks is higher than that implied by the synchrotron radiation reaction limit, indicating that the flare emission regions Doppler factors are ? a few. We conclude that magnetic reconnection can be an important, if not dominant, mechanism of particle acceleration within the nebula.

引用

页码：1374 / 1384

页数：11

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