Spectral features in gamma-rays expected from millisecond pulsars

Citation
T. Bulik et al., Spectral features in gamma-rays expected from millisecond pulsars, M NOT R AST, 317(1), 2000, pp. 97-104
Citations number
26
Categorie Soggetti
Space Sciences
Journal title
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN journal
00358711 → ACNP
Volume
317
Issue
1
Year of publication
2000
Pages
97 - 104
Database
ISI
SICI code
0035-8711(20000901)317:1<97:SFIGEF>2.0.ZU;2-6
Abstract
In the advent of next generation gamma-ray missions, we present general pro perties of spectral features of high-energy emission above 1 MeV expected f or a class of millisecond, low magnetic field (similar to 10(9) G) pulsars. We extend polar-cap model calculations of Rudak & Dyks by including invers e Compton scattering events in an ambient field of thermal X-ray photons an d 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 c urvature radiation spectrum in the energy range from 100 MeV to 10 GeV stro ngly depends on the model of longitudinal acceleration, whereas below simil ar to 100 MeV all slopes converge to a unique value of 4/3 (in a nu F-nu co nvention). 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 dom ain and form a separate spectral component peaking at similar to 1 TeV. We discuss the observability of millisecond pulsars by future high-energy inst ruments and present two rankings relevant for GLAST and MAGIC. We point to the pulsar J0437-4715 as a promising candidate for observations.