Spectral features in gamma-rays expected from millisecond pulsars |
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Authors: | T. Bulik B. Rudak J. Dyks |
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Affiliation: | Nicolaus Copernicus Astronomical Center, Bartycka 18, 00716 Warsaw, Poland;Nicolaus Copernicus Astronomical Center, Rabiańska 8, 87100 Toruń, Poland;TCfA of Nicolaus Copernicus University, Gagarina 11, 87100 Toruń, Poland |
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Abstract: | In the advent of next generation gamma-ray missions, we present general properties of spectral features of high-energy emission above 1 MeV expected for a class of millisecond, low magnetic field (∼109 G) pulsars. We extend polar-cap model calculations of Rudak & Dyks by including inverse Compton scattering events in an ambient field of thermal X-ray photons and by allowing for two models of particle acceleration. In the range between 1 MeV and a few hundred GeV, the main spectral component is the result of curvature radiation of primary particles. The synchrotron component arising from secondary pairs becomes dominant only below 1 MeV. The slope of the curvature radiation spectrum in the energy range from 100 MeV to 10 GeV strongly depends on the model of longitudinal acceleration, whereas below ∼100 MeV all slopes converge to a unique value of 4/3 (in a ν ℱ ν convention). The thermal soft X-ray photons, which come either from the polar cap or from the surface, are Compton upscattered to a very high energy domain and form a separate spectral component peaking at ∼1 TeV. We discuss the observability of millisecond pulsars by future high‐energy instruments and present two rankings relevant for GLAST and MAGIC. We point to the pulsar J0437−4715 as a promising candidate for observations. |
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Keywords: | pulsars: general gamma-rays: observations gamma-rays: theory |
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