RADIO-TO-TeV PHASE-RESOLVED EMISSION FROM THE CRAB PULSAR: THE ANNULAR GAP MODEL
- National Astronomical Observatories, Chinese Academy of Sciences, Jia 20 Datun Road, Beijing 100012 (China)
The Crab pulsar is a quite young, famous pulsar that radiates multi-wavelength pulsed photons. The latest detection of GeV and TeV pulsed emission with an unprecedented signal-to-noise ratio, supplied by the powerful telescopes Fermi, MAGIC, and VERITAS, challenges the current popular pulsar models, and can be a valuable discriminator to justify the pulsar high-energy-emission models. Our work is divided into two steps. First, taking reasonable parameters (the magnetic inclination angle {alpha} = 45 Degree-Sign and the view angle {zeta} = 63 Degree-Sign ), we use the latest high-energy data to calculate radio, X-ray, {gamma}-ray, and TeV light curves from a geometric view to obtain crucial information on emission locations. Second, we calculate the phase-averaged spectrum and phase-resolved spectra for the Crab pulsar and take a theoretical justification from a physical view for the emission properties as found in the first step. It is found that a Gaussian emissivity distribution with the peak emission near the null charge surface in the so-called annular gap (AG) region gives the best modeled light curves. The pulsed radio, X-ray, {gamma}-ray, and TeV emission are mainly generated from the emission of primary particles or secondary particles with different emission mechanisms in the nearly similar region of the AG located in the only magnetic pole, which leads to the nearly 'phase-aligned' multi-wavelength light curves. The emission of peak 1 and peak 2 originates from the AG region near the null charge surface, while the emission of the bridge primarily originates from the core gap (CG) region. The charged particles cannot co-rotate with the pulsar and escape from the magnetosphere, which determines the original flowing primary particles. The acceleration electric field and potential in the AG and CG are huge enough and are in the several tens of neutron star radii. Thus, the primary particles are accelerated to ultra-relativistic energies and produce numerous secondary particles (pairs) in the inner regions of the AG and CG. We emphasize that there are mainly two types of pairs: one is curvature-radiation induced (CR-induced) and the other is inverse-Compton-scattering induced (ICS-induced). The phase-averaged spectrum and phase-resolved spectra from soft X-ray to TeV bands are produced by four components: synchrotron radiation from CR- and ICS-induced pairs dominates the X-ray band to soft {gamma}-ray band (100 eV to 10 MeV); curvature radiation and synchrotron radiation from the primary particles mainly contribute to the {gamma}-ray band (10 MeV to {approx}20 GeV); ICS from the pairs significantly contributes to the TeV {gamma}-ray band ({approx}20-400 GeV). The multi-wavelength pulsed emission from the Crab pulsar can be well modeled with the AG and CG model. To distinguish our single magnetic pole model from two-pole models, the convincing values of the magnetic inclination angle and the viewing angle will play a key role.
- OSTI ID:
- 22016121
- Journal Information:
- Astrophysical Journal, Vol. 748, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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