Open AccessSpectral features in gamma‐rays expected from millisecond pulsars
Author(s) -
Bulik T.,
Rudak B.,
Dyks J.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03662.x
Subject(s) - physics , millisecond pulsar , pulsar , astrophysics , compton scattering , photon , gamma ray , particle acceleration , electron , nuclear physics , optics
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 (∼10 9 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 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.