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Modeling of the NICER X-ray waveform of the pulsar PSR J0030+0451, aimed to constrain the neutron star mass and radius, has inferred surface hot-spots (the magnetic polar caps) that imply significantly non-dipolar magnetic fields. To this…

High Energy Astrophysical Phenomena · Physics 2021-02-10 Constantinos Kalapotharakos , Zorawar Wadiasingh , Alice K. Harding , Demosthenes Kazanas

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

Recently, it was proposed that an off-center dipole magnetic configuration, together with a non-trivial temperature profile, may be the best model to explain the X-ray light curve of PSR J0030+0451 observed by the Neutron Star Interior…

High Energy Astrophysical Phenomena · Physics 2025-10-22 Chun Huang , Alexander Y. Chen

The influence of surface small scale magnetic field on the heating of PSR J0250+5854 polar cap is considered. It is assumed that polar cap is heated only by reverse positrons, accelerated in pulsar diode. It is supposed that pulsar diode is…

High Energy Astrophysical Phenomena · Physics 2022-01-05 D. P. Barsukov , M. V. Vorontsov , I. K. Morozov

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

The results of Monte-Carlo simulations of electron-positron-photon cascades initiated by slow electrons in circularly polarized fields of ultra-high strength are presented and discussed. Our results confirm previous qualitative estimations…

High Energy Physics - Phenomenology · Physics 2011-05-23 N. V. Elkina , A. M. Fedotov , I. Yu. Kostyukov , M. V. Legkov , N. B. Narozhny , E. N. Nerush , H. Ruhl

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

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 consider the effect of rapid rotation on the light curves of neutron stars with hot polar caps. For $P \approx 3$ms spin periods, the pulse fractions can be as much as an order of magnitude larger than with simple slowly-rotating…

Astrophysics · Physics 2009-10-31 Timothy M. Braje , Roger W. Romani , Kevin P. Rauch

We modify the conventional curvature radiation (inverse Compton scattering) + synchrotron radiation polar cap cascade model by including the inverse Compton scattering of the higher generation pairs. Within the framework of the…

Astrophysics · Physics 2009-10-31 Bing Zhang , Alice K. Harding

The topology of the electromagnetic field around neutron stars severely impacts pulsar physics. While most of the works assume a standard centred dipolar magnetic field model, recently some efforts have been made to explain how inclusion of…

High Energy Astrophysical Phenomena · Physics 2017-07-27 Anu Kundu , Jerome Petri

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

The magnetic field of magnetars may be twisted compared with that of normal pulsars. Previous works mainly discussed magnetic energy release in the closed field line regions of magnetars. For a twisted magnetic field, the field lines will…

High Energy Astrophysical Phenomena · Physics 2019-09-25 H. Tong

Supplementing our STM and electron emission studies investigations, concluding in electron pairing in strong laser fields [1], further time-of-flight electron emission studies were carried out, changing the angle of polarization of the…

Optics · Physics 2015-06-02 N. Kroó , P. Rácz , S. Varró

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

We explore the role of complex multipolar magnetic fields in determining physical processes near the surface of rotation powered pulsars. We model the actual magnetic field as the sum of global dipolar and star-centered multipolar fields.…

Astrophysics · Physics 2009-11-07 Estelle Asseo , David Khechinashvili

Millisecond pulsars (MSPs) are believed to be very old neutron stars (NSs) whose age may exceed significantly $10^8$ yrs. Although cooling scenarios of isolated NSs predict for that age a surface temperature $T_s\sim 10^4$ K, observations…

High Energy Astrophysical Phenomena · Physics 2024-04-05 U. Geppert

Disk accretion to rotating stars with complex magnetic fields is investigated using full three-dimensional magnetohydrodynamic (MHD) simulations. The studied magnetic configurations include superpositions of misaligned dipole and quadrupole…

Astrophysics · Physics 2009-11-13 M. Long , M. M. Romanova , R. V. E. Lovelace

Observations by the Fermi Large Area Telescope of gamma-ray millisecond pulsar light curves imply copious pair production in their magnetospheres, and not exclusively in those of younger pulsars. Such pair cascades may be a primary source…

High Energy Astrophysical Phenomena · Physics 2015-07-15 C. Venter , A. Kopp , A. K. Harding , P. L. Gonthier , I. Büsching

Resonant inverse Compton scattering (RICS) of soft thermal photons by relativistic particles on closed magnetic field loops has been proposed to explain the hard emission observed up to, and beyond, 200 keV from magnetars. If particles…

High Energy Astrophysical Phenomena · Physics 2025-08-20 Alice K. Harding , Zorawar Wadiasingh , Matthew G. Baring