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Generation of ultrarelativistic polarized positrons during interaction of an ultrarelativistic electron beam with a counterpropagating two-color petawatt laser pulse is investigated theoretically. Our Monte Carlo simulation based on a…

We have programmed a full simulation of the open field lines above the polar cap of a magnetized pulsar, using time dependent Particle In Cell (PIC) numerical code (Birdsall and Langdon 1991). We consider the case of free ejection of…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Yudith Barzilay

The radio emission in many pulsars show sudden changes, usually within a period, that cannot be related to the steady state processes within the inner acceleration region (IAR) above the polar cap. These changes are often quasi-periodic in…

High Energy Astrophysical Phenomena · Physics 2021-06-09 U. Geppert , R. Basu , D. Mitra , G. Melikidze , M. Szkudlarek

In a strong magnetic field, B > 4x10^{12} G, gamma-rays emitted nearly along curved field lines adiabatically convert into bound electron-positron pairs (positronium atoms) rather that decaying into free pairs. This process may modify the…

High Energy Astrophysical Phenomena · Physics 2011-09-27 Anatoly E. Shabad , Vladimir V. Usov

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

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

Rotation distorts the vacuum magnetic field of a pulsar from that of a simple dipole. The effect is particularly strong close to the light cylinder, but also affects the field close to the stellar surface. We find the shape and locus of the…

Astrophysics · Physics 2012-08-27 P. N. Arendt, , J. A. Eilek

Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields…

High Energy Astrophysical Phenomena · Physics 2016-12-21 Samuel E. Gralla , Alexandru Lupsasca , Alexander Philippov

We show results of global 3D MHD simulations of accretion onto stars with superposition of the dipole and octupole fields, where we vary the ratio between components. Simulations show that if octupolar field strongly dominates at the…

High Energy Astrophysical Phenomena · Physics 2015-05-14 Min Long , Marina M. Romanova , Frederick K. Lamb

Recent advances in numerical algorithms and computational power have enabled first-principles simulations of pulsar magnetospheres using Particle-in-Cell (PIC) techniques. These ab-initio simulations seem to indicate that pair creation…

High Energy Astrophysical Phenomena · Physics 2020-02-05 Alexander Y. Chen , Fabio Cruz , Anatoly Spitkovsky

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

Collisionless absorption of laser energy by an electron via laser-cluster interaction in an ambient magnetic field ($B_0$) has recently renewed interest. %due to high levels of absorption. Previously, using a rigid sphere model (RSM) and an…

Plasma Physics · Physics 2024-05-27 Kalyani Swain , Mrityunjay Kundu

Pulsars have been identified as good candidates for the acceleration of cosmic rays, up to ultra-high energies. However, a precise description of the acceleration processes at play is still to be established. Using 2D particle-in-cell…

High Energy Astrophysical Phenomena · Physics 2020-03-25 C. Guépin , B. Cerutti , K. Kotera

Magnetars, neutron stars thought to be with ultra-strong magnetic fields of $10^{14 - 15}$ G, are observed to be much hotter than ordinary pulsars with $\sim 10^{12}$ G, and additional heating sources are required. One possibility is…

High Energy Astrophysical Phenomena · Physics 2023-03-29 Sachiko Tsuruta , Madeline J. Kelly , Ken'ichi Nomoto , Kanji Mori , Marcus Teter , Andrew C. Liebmann

Electric currents j flow along the open magnetic field lines from the polar caps of neutron stars. Activity of a polar cap depends on the ratio \alpha=j/c\rho_GJ, where \rho_GJ is the corotation charge density. The customary assumption…

Astrophysics · Physics 2009-11-13 Andrei M. Beloborodov

The observed spectra and X-ray luminosities of millisecond pulsars in 47 Tuc can be interpreted in the context of theoretical models based on strong, small scale multipole fields on the neutron star surface. For multipole fields that are…

Astrophysics · Physics 2009-11-10 K. S. Cheng , Ronald E. Taam

It has recently been suggested that two counter-propagating, circularly polarized, ultra-intense lasers can induce a strong electron spin polarization at the magnetic node of the electromagnetic field that they setup. We confirm these…

Plasma Physics · Physics 2018-04-16 Dario Del Sorbo , Daniel Seipt , Alexander G. R. Thomas , Christopher P. Ridgres

By applying Monte Carlo simulations we found that the extraction of bound polaron pairs (PP) at the electrodes is an important loss factor limiting the efficiency of organic optoelectronic and photovoltaic devices. Based upon this finding,…

Materials Science · Physics 2011-01-06 T. Strobel , C. Deibel , V. Dyakonov

We use a 3D Monte Carlo radiative transfer code to study the polarimetric and photometric variability from stationary corotating interaction regions (CIR) in the wind of massive stars. Our CIRs are approximated by Archimedean spirals of…

Solar and Stellar Astrophysics · Physics 2019-09-25 Danny Carlos-Leblanc , Nicole St-Louis , Jon Bjorkman , Richard Ignace

Recent modeling of NICER observations of thermal X-ray pulsations from the surface of the isolated millisecond pulsar PSR J0030+0451 suggests that the hot emitting regions on the pulsar's surface are far from antipodal, which is at odds…