Abstract
The notable absence of radio pulsars having measured magnetic dipole surface field strengths above B -->0~3×10 -->13 G naturally raises the question of whether this forms an upper limit to pulsar magnetization. Recently there has been increasing evidence that neutron stars possessing higher dipole spin-down fields do in fact exist, including a growing list of anomalous X-ray pulsars (AXPs) with long periods and spinning down with high-period derivatives, which imply surface fields of 1014-1015 G. Furthermore, the recently reported X-ray period and period derivative for the soft gamma-ray repeater (SGR) source SGR 1806-20 suggest a surface field around 1015 G. None of these high-field pulsars have yet been detected as radio pulsars. We propose that high-field pulsars should be radio quiet because electron-positron pair production in their magnetospheres, thought to be essential for radio emission, is efficiently suppressed in ultrastrong fields (B -->04×10 -->13 G) by the action of photon splitting, a quantum electrodynamical process in which a photon splits into two. Our computed radio quiescence boundary in the radio pulsar P-${u{P}{705F}}$ -->${u{P}{705F}}$ --> diagram, where photon splitting overtakes pair creation, is located just above the boundary of the known radio pulsar population, neatly dividing them from the AXPs. We thus identify a physical mechanism that defines a new class of high-field radio-quiet neutron stars that should be detectable by their pulsed emission at X-ray and perhaps gamma-ray energies.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.