Detection of UHE gamma rays from the Crab Nebula: Physical Implications

Abstract

The Crab Nebula is an extreme particle accelerator boosting the energy of electrons up to a few PeV ($10^{15}\mathrm{eV}$), close to the maximum energy allowed by theory. The physical conditions in the acceleration site and the nature of the acceleration process itself remain highly uncertain. The key information about the highest energy accelerated particles is contained in the synchrotron and inverse Compton (IC) channels of radiation at energies above 1~MeV and 100~TeV, respectively. The recent report of detection of ultra-high energy gamma-ray signal from the Crab Nebula up to 300~TeV allows one to determine the energy distribution of the highest energy electrons and to derive the magnetic field strength in the acceleration region, $B\le 120\mu \mathrm{G}$, in a parameter-free way. This estimate brings new constraints on the properties of non-thermal particle distributions and puts important constraints on the MHD models for the Crab Nebula, in particular on the feasible magnetization and anisotropy of the pulsar wind. The calculations of synchrotron and IC emission show that future observations with instruments allowing detection of the Crab Nebula above 300~TeV and above 1~MeV will clarify the conditions allowing acceleration of electrons beyond PeV energies in the Crab Nebula. In particular, one will (1) verify the hypothetical multi-component composition of the electron energy distribution, and (2) determine the magnetic field strength in the regions responsible for the acceleration of PeV electrons.

8 pages, 5 figures, MNRAS accepted

References in corpus (8)

• Observations of the Crab Nebula with H.E.S.S
• Gamma-ray flares from the Crab Nebula
• Discovery of Powerful Gamma-Ray Flares from the Crab Nebula
• VHE Gamma-Ray Observation of the Crab Nebula and its Pulsar with the MAGIC telescope
• Absorption of Very High Energy Gamma Rays in the Milky Way
• Non-thermal emission from relativistic MHD simulations of PWNe: from synchrotron to inverse Compton
• Broadband X-ray Imaging and Spectroscopy of the Crab Nebula and Pulsar with NuSTAR
• Constraints on particle acceleration sites in the Crab Nebula from relativistic MHD simulations

Cited by in corpus (6)

• The Hunt for Pevatrons: The Case of Supernova Remnants
• Multi-band Emission up to PeV Energy from the Crab Nebula in a Spatially Dependent Lepto-hadronic Model
• From young to old: the evolutionary path of Pulsar Wind Nebulae
• Detection of Small Flares from the Crab Nebula with Fermi-LAT
• Ultrahigh-energy Gamma-Ray Radiation from the Crab Pulsar Wind Nebula
• Constraints on the $e^{\pm }$ Pair Injection of Pulsar Halos: Implications from the Galactic Diffuse Multi-TeV Gamma-ray Emission