Related papers: Time-Dependent Electron Acceleration in Pulsar Win…
The $\gamma$-ray flares from the Crab nebula observed by {\it AGILE} and {\it Fermi}-LAT between 2007-2013 reached GeV photon energies and lasted several days. The strongest emission, observed during the 2011 April "super-flare," exceeded…
The {\gamma}-ray flares from the Crab nebula observed by AGILE and Fermi-LAT reaching GeV energies and lasting several days challenge the standard models for particle acceleration in pulsar wind nebulae, because the radiating electrons have…
The recent discovery of PeV electrons from the Crab nebula, produced on rapid time scales of one day or less with a sharply peaked gamma-ray spectrum without hard X-rays, challenges traditional models of diffusive shock acceleration…
The recent discovery of day-long gamma-ray flares in the Crab Nebula, presumed to be synchrotron emission by PeV (10^{15} eV) electrons in milligauss magnetic fields, presents a strong challenge to particle acceleration models. The observed…
The remarkable Crab Nebula is powered by an energetic pulsar whose relativistic wind interacts with the inner parts of the Supernova Remnant SN1054. Despite low-intensity optical and X-ray variations in the inner Nebula, the Crab has been…
The gamma-ray space telescopes AGILE and Fermi detected short and bright synchrotron gamma-ray flares at photon energies above 100 MeV in the Crab Nebula. This discovery suggests that electron-positron pairs in the nebula are accelerated to…
We report on the extremely intense and fast gamma-ray are above 100 MeV detected by AGILE from the Crab Nebula in mid-April 2011. This event is the fourth of a sequence of reported major gamma-ray flares produced by the Crab Nebula in the…
The well known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally-powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar…
Strong gamma-ray flares from the Crab Nebula have been recently discovered by AGILE and confirmed by Fermi-LAT. We study here the spectral evolution in the gamma-ray energy range above 50 MeV of the September 2010 flare that was…
We develop a model of gamma-ray flares of the Crab Nebula resulting from the magnetic reconnection events in highly-magnetized relativistic plasma. We first discuss physical parameters of the Crab nebula and review the theory of pulsar…
Very high energy gamma-ray flares from the Crab nebular detected by AGILE and Fermi satellites challenge our understanding of the pulsar wind nebulae. The short duration of the flares, only few days, is particularly puzzling since it is…
Aims. The Crab nebula displayed a large gamma-ray flare on September 18, 2010. To more closely understand the origin of this phenomenon, we analyze the INTEGRAL (20-500 keV) and FERMI (0.1-300 GeV) data collected almost simultaneously…
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…
Recent results from LHAASO and Tibet AS$\gamma$ suggest that the Crab Nebula's gamma-ray spectrum extends to the PeV energy range, however the production mechanisms of this highest energy emission remain unclear. It has been postulated that…
The Crab Nebula emits bright non-thermal radiation from radio to the most energetic photons. The underlying physical model of a relativistic wind from the pulsar terminating in a hydrodynamic standing shock remains unchanged since the early…
We study particle acceleration at the termination shock of a striped pulsar wind by integrating trajectories in a prescribed model of the magnetic field and flow pattern. Drift motion on the shock surface maintains either electrons or…
The Crab nebula is one of the most studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very high-energy gamma rays. It is known from radio to gamma-ray observations that the nebula is…
Gamma-ray emission from the Crab Nebula has been recently shown to be unsteady. In this paper, we study the flux and spectral variability of the Crab above 100 MeV on different timescales ranging from days to weeks. In addition to the four…
Synchrotron radiation of ultra-relativistic particles accelerated in a pulsar wind nebula may dominate its spectrum up to gamma-ray energies. Because of the short cooling time of the gamma-ray emitting electrons, the gamma-ray emission zone…
We will present our study of the flux and spectral variability of the Crab above 100 MeV on different timescales ranging from days to weeks. In addition to the four main intense and day-long flares detected by AGILE and Fermi-LAT between…