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The absence of radio pulsars with long periods has lead to the popular notion of a high P ``death line.'' In the standard picture, beyond this boundary, pulsars with low spin rates cannot accelerate particles above the stellar surface to…

Astrophysics · Physics 2009-10-31 Matthew G. Baring , Alice K. Harding

Pulsar radio emission is believed to be originated from the electron-positron pairs streaming out from the polar cap region. Pair formation, an essential condition for pulsar radio emission, is believed to be sustained in active pulsars via…

Astrophysics · Physics 2007-05-23 Bing Zhang

We study coupled axial and polar axisymmetric oscillations of a neutron star endowed with a strong magnetic field, having both poloidal and toroidal components. The toroidal component of the magnetic field is driving the coupling between…

High Energy Astrophysical Phenomena · Physics 2012-05-08 A. Colaiuda , K. D. Kokkotas

Time-dependent cascades of electron-positron pairs are thought to be the main source of plasma in pulsar magnetospheres and a primary ingredient to explain the nature of pulsar radio emission, a longstanding open problem in high-energy…

High Energy Astrophysical Phenomena · Physics 2022-05-18 Fábio Cruz , Thomas Grismayer , Simon Iteanu , Paolo Tortone , Luis O. Silva

The main issue of the pulsar magnetosphere is how the rotation power is converted into both particle beams which causes pulsed emissions, and a highly relativistic wind of electron-positron plasmas which forms surrounding nebulae shining in…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Tomohide Wada , Shinpei Shibata

Motivated by the recent detection of ultra-long period radio transients, we investigate new models of coherent radio emission via low-altitude electron-positron pair production in neutron stars beyond rotationally-powered curvature…

High Energy Astrophysical Phenomena · Physics 2024-07-24 A. J. Cooper , Z. Wadiasingh

We investigate a pair creation cascade in the magnetosphere of a rapidly rotating neutron star. We solve the set of the Poisson equation for the electro-static potential and the Boltzmann equations for electrons, positrons, and gamma-ray…

Astrophysics · Physics 2007-05-23 P. C. Hsu , K. Hirotani , H. K. Chang

In the canonical model of a pulsar, rotational energy is transmitted through the surrounding plasma via two electrical circuits, each connecting to the star over a small region known as a "polar cap." For a dipole-magnetized star, the polar…

High Energy Astrophysical Phenomena · Physics 2018-01-03 Samuel E. Gralla , Alexandru Lupsasca , Alexander Philippov

Pulsar magnetospheres are thought to be filled with electron-positron plasma generated in pair cascades. The driving mechanism of these cascades is the emission of gamma-ray photons and their conversion into pairs via Quantum…

High Energy Astrophysical Phenomena · Physics 2021-09-30 Fábio Cruz , Thomas Grismayer , Alexander Y. Chen , Anatoly Spitkovsky , Luis O. Silva

We investigate the physical situation above the pulsar polar cap (PC) where the accelerating primaries (electrons) are not capable of producing sufficient numbers of electron-positron pairs at low altitudes (within 1-2 stellar radii above…

Astrophysics · Physics 2009-11-10 Alex G. Muslimov , Alice K. Harding

Aims. Many recent observations of pulsars and magnetars can be interpreted in terms of neutron stars (NS) with multipole electromagnetic fields. As a first approximation, we investigate the multipole magnetic and electric fields in the…

High Energy Astrophysical Phenomena · Physics 2020-07-07 S. Bonazzola , F. Mottez , J. Heyvaerts

Expanding on the comment by Lyne et al (2017), that intermittent pulsars tend to congregate near a stripe in the logarithmic period versus period-derivative diagram, representing a small range of polar cap electric potential, as well as the…

High Energy Astrophysical Phenomena · Physics 2021-11-24 Fan Zhang

An analytical model for oscillating pair creation above the pulsar polar cap is presented in which the parallel electric field is treated as a large amplitude, superluminal, electrostatic wave. An exact formalism for such wave is derived in…

Astrophysics · Physics 2009-11-13 Q. Luo , D. B. Melrose

Electron-positron pair cascades developed in the extreme electromagnetic fields of neutron star polar caps are considered a key source of magnetospheric plasma in these objects. We use a simplified model that maps the Quantum…

High Energy Astrophysical Phenomena · Physics 2021-03-03 Fábio Cruz , Thomas Grismayer , Luis O. Silva

We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole $B$-fields (the latter is characterized by a parameter $\epsilon$), in conjunction with standard two-pole caustic (TPC) and…

High Energy Astrophysical Phenomena · Physics 2017-01-12 Monica Barnard , Christo Venter , Alice K. Harding

Modifications to polar-gap models for pulsars are discussed for the case where the surface magnetic field, $B_\S$, of the neutron star is strong. For $B\ga4\times10^8\rm\,T$, the curvature $\gamma$-quanta emitted tangentially to the curved…

Astrophysics · Physics 2015-06-24 V. V. Usov , D. B. Melrose

Recent studies have shown that gamma-ray pulsar light curves are very sensitive to the geometry of the pulsar magnetic field. Pulsar magnetic field geometries, such as the retarded vacuum dipole and force-free magnetospheres have distorted…

High Energy Astrophysical Phenomena · Physics 2011-11-04 Alice K. Harding , Megan E. DeCesar , M. Coleman Miller , Constantinos Kalapotharakos , Ioannis Contopoulos

We investigate the conditions required for the production of electron-positron pairs above a pulsar polar cap (PC) and the influence of pair production on the energetics of the primary particle acceleration. Assuming space-charge limited…

Astrophysics · Physics 2016-08-30 Alice K. Harding , Alexander G. Muslimov , Bing Zhang

We analytically investigate the condition for a particle accelerator to be active in the outer magnetosphere of a rotation-powered pulsar. Within the accelerator (or the gap), magnetic-field-aligned electric field accelerates electrons and…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Ren-Bo Wang , Kouichi Hirotani

The formation of $e^\pm$ plasmas within pulsar magnetospheres through quantum electrodynamics (QED) cascades in vacuum gaps is widely acknowledged. This paper aims to investigate the effect of photon polarization during the QED cascade…

High Energy Astrophysical Phenomena · Physics 2024-04-30 Huai-Hang Song , Matteo Tamburini