Three-dimensional Two-Layer Outer Gap Model: Fermi Energy Dependent Light Curves of the Vela Pulsar

Abstract

We extend the two-dimensional two-layer outer gap model to a three-dimensional geometry and use it to study the high-energy emission of the Vela pulsar. In this model, the outer gap is divided into two parts, i.e. the main acceleration region on the top of last-open field lines and the screening region around the upper boundary of the gap. In the main acceleration region, the charge density is much lower than the Goldreich-Julian charge density and the charged particles are accelerated by the electric field along the magnetic field to emit multi-GeV photons. In the screening region, the charge density is larger than the Goldreich-Julian value to close the gap and particles in this region are responsible for multi-100MeV photon emission. We apply this three dimensional two-layer model to the Vela pulsar and compare the model light curves, the phase-averaged spectrum and the phase-resolved spectra with the recent Fermi observations, which also reveals the existence of the third peak between two main peaks. The phase position of the third peak moves with the photon energy, which cannot be explained by the geometry of magnetic field structure and the caustic effects of the photon propagation. We suggest that the existence of the third peak and its energy dependent movement results from the azimuthal structure of the outer gap.

11 pages, 15 figures, accepted for publication in MNRAS

References in corpus (6)

• High-Altitude Emission from Pulsar Slot Gaps: The Crab Pulsar
• Outer-gap vs. Slot-gap Models for Pulsar High Energy Emissions: The Case of the Crab Pulsar
• Particle Acceleration and Non-Thermal Emission in Pulsar Outer Magnetospheric Gap
• Gamma-ray spectral properties of mature pulsars: a two-layer model
• Gamma-ray Emission from the Vela Pulsar Modeled with the Annular Gap and Core Gap
• Non-thermal emissions from outer magnetospheric accelerators of middle-aged pulsars

Cited by in corpus (16)

• The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Constraints on the Emission Geometries and Spin Evolution of Gamma-ray Millisecond Pulsars
• First Ground-based Measurement of Sub-20 GeV to 100 GeV $\gamma$-rays from the Vela Pulsar with H.E.S.S. II
• Lepton acceleration in the vicinity of the event horizon: High-energy and Very-high-energy emissions from rotating black holes with various masses
• Luminosity Evolution of Gamma-ray Pulsars
• An assessment of the pulsar outer gap model. I: Assumptions, uncertainties, and implications for the gap size and the accelerating field
• Observation and Simulation of the Variable Gamma-ray Emission from PSR~J2021+4026
• High-Energy Emission of the First Millisecond Pulsar
• Asymmetry of bifurcated features in radio pulsar profiles
• Population study for gamma-ray pulsars: (III) Radiation characteristics and viewing geometry
• Mechanism of the X-ray and Soft Gamma-ray Emissions from High Magnetic Field Pulsar: PSR B1509-58
• Emission Patterns and Light Curves of Gamma-Rays in the Pulsar Magnetosphere with a Current-Induced Magnetic Field
• Constraints on the Emission Geometries of Gamma-ray Millisecond Pulsars Observed with the Fermi Large Area Telescope
• Modeling the High-energy Emission from the Gamma-ray Binary 1FGL J1018.6-5856
• Dark neutron stars
• Radiation Mechanism of the Soft Gamma-ray Pulsar PSR B1509-58