On the Origin and Physics of Gamma Flares in Crab Nebula

Abstract

We consider parametric generation of electrostatic waves in the magnetosphere of the pulsar PSR0531. It is shown that in the framework of this mechanism it is possible to convert the pulsar rotational energy into the energy of Langmuir waves. The maximum growth rate is achieved in the "superluminal" area, where phase velocity of perturbations is exceeding the speed of light. Therefore electromagnetic waves do not damp on particles. Instead, they create plasmon condensate, which is carried out, outside of the pulsar magnetosphere and reaches the Crab nebula. It is shown, that the transfer of the energy of the plasmon condensate from the light cylinder to the active region of the nebula happens practically without losses. Unlike the plasma of the magnetosphere, the one of nebula contains ions, i.e., it may sustain modulation instability, which leads to the collapse of the Langmuir condensate. Langmuir wave collapse, in turn, leads to the acceleration of the distribution function particles. Furthermore, we consider processes leading to the self-trapping of the synchrotron radiation, resulting in the growth of the radiation intensity, which manifests itself observationally as a flare. The condition for the self-trapping onset is derived, showing that if the phenomena takes place at 100MeV , then it doesn't happen at lower (or higher) energies. This specific kind of higher/lower energy cutoff could explain why when we observe the flare at 100 MeV no enhanced emission is observed at lower/higher energies! Subject headings: pulsars: general -pulsars: individual(PSR0531)

The Crab nebula energy origin and its high frequency radiation spectra

“…2013; Machabeli et al. 2015). We have performed the estimation of the possibility of an idealized mechanism of rotational energy pumping.…”

“…As a result, the condensate of electrostatic oscillations is formed (Machabeli et al. 2015). This plasmon condensate is transferred into the nebula practically without any energy losses. Differently from the pulsar magnetosphere, the nebula also contains ions.…”

“…Previously, we have shown that the parametric generation of Langmuir waves, when ω/k > c, happens with a higher increment than for ω/k c (Machabeli et al 2015). Such superluminal waves cannot be damped in the pulsar magnetosphere and the Langmuir oscillations are accumulated, which transfer energy along the magnetic field lines and finally into the Crab nebula.…”

“…2013; Machabeli et al. 2015). Section 3 is devoted to considering this problem, where we show that the pulsar rotational energy is pumped into the Langmuir perturbations mainly in the long-wavelength region, where the phase velocity of the wave exceeds the speed of light .…”

“…In § 2 we consider in detail a problem of the motion of a relativistic particle along a rotating rigid string (Machabeli & Rogava 1994). The paper considering this problem provided us with a theoretical framework that was later used to consider the problem of pulsar rotational energy pumping into the electrostatic waves of magnetospheric plasma (Machabeli et al 2005;Mahajan et al 2013;Machabeli et al 2015). Section 3 is devoted to considering this problem, where we show that the pulsar rotational energy is pumped into the Langmuir perturbations mainly in the long-wavelength region, where the phase velocity of the wave exceeds the speed of light v ph = ω/k > c. As particles with such speed do not exist, the waves propagate without damping.…”