Dark neutron stars

Abstract

There is good evidence that electron-positron pair formation is not present in that section of the pulsar open magnetosphere which is the source of coherent radio emission, but the possibility of two-photon pair creation in an outer gap remains. Calculation of transition rates for this process based on measured whole-surface temperatures, combined with a survey of gamma-ray, X-ray and optical luminosities, expressed per primary beam lepton, shows that few Fermi LAT pulsars have significant outer-gap pair creation. For radio-loud pulsars with positive polar-cap corotational charge density and an ion-proton plasma there must be an outward flow of electrons from some other part of the magnetosphere to maintain a constant net charge on the star. In the absence of pair creation, it is likely that this current is the source of GeV gamma-emission observed by the Fermi LAT and its origin is in the region of the outer gap. With negative polar-cap corotational charge density, the compensating current in the absence of pair creation can consist only of ion or protons. These neutron stars are likely to be radio-quiet, have no observable gamma-emission, and hence can be described as dark neutron stars.

9 pages

References in corpus (8)

• The ATNF Pulsar Catalogue
• The variable radio-to-X-ray spectrum of the magnetar XTE J1810-197
• Constraining the Spin-down of the Nearby Isolated Neutron Star RX J2143.0+0654
• Simultaneous multi-frequency single-pulse properties of AXP XTE J1810-197
• Particle Acceleration and Non-Thermal Emission in Pulsar Outer Magnetospheric Gap
• Compact formulae, dynamics and radiation of charged particles under synchro-curvature losses
• A systematic synchro-curvature modelling of pulsar $\gamma$-ray spectra unveils hidden trends
• The mechanism of coherent radio emission in some classes of pulsar