2011ApJ...739...14K

Using the outer gap model, we investigate the emission region for the multi-wavelength light curve from energetic pulsars. We assume that γ-ray and non-thermal X-ray photons are emitted from a particle acceleration region in the outer magnetosphere, and UV/optical photons originate above that region. We assume that γ-rays are radiated only by outwardly moving particles, whereas the other photons are produced by particles moving inward and outward. We parameterize the altitude of the emission region as the deviation from the rotating dipole in a vacuum and determine it from the observed multi-wavelength pulse profile using the observationally constrained magnetic dipole inclination angle and viewing angle of the pulsars. We find that the outer gap model can explain the multi-wavelength pulse behavior by a simple distribution of emissivity, and discuss the possibility of further improvement. From observational fitting, we also find a general tendency for the altitude of the γ-ray emission region to depend on the inclination angle. In particular, the emission region for low inclination angle is required to be located at very low altitude, which corresponds to the inner region within the last-open field line of the rotating dipole in a vacuum. This model suggests a modification of the statistics for observed γ-ray pulsars: the number of sources with low inclination and viewing angles increases compared with previous estimates.