TY - JOUR
T1 - Three-dimensional analytical description of magnetized winds from oblique pulsars
AU - Tchekhovskoy, Alexander
AU - Philippov, Alexander
AU - Spitkovsky, Anatoly
N1 - Funding Information:
We thank Jon Arons, Andrei Beloborodov, Vasily Beskin, and Rolf Buehler for insightful discussions. AT was supported by NASA through Einstein Post-doctoral Fellowship grant number PF3-140131 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060, and NASA via High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center that provided access to the Pleiades supercomputer, as well as NSF through an XSEDE computational time allocation TG-AST100040 on NICS Kraken, Nautilus, TACC Stampede, Maverick, and Ranch. AP was supported by NASA Earth and Space Science Fellowship Program (grant number NNX15AT50H). This work was supported in part by NASA grant NNX14AQ67G and Simons Foundation (grant 267233 to AS). We used ENTHOUGHT CANOPY PYTHON distribution to generate figures for this work.
Publisher Copyright:
© 2016 The Authors.
PY - 2016/4/11
Y1 - 2016/4/11
N2 - Rotating neutron stars, or pulsars and magnetars, are plausibly the source of power behind many astrophysical systems, such as gamma-ray bursts, supernovae, pulsar wind nebulae, and supernova remnants. In the past several years, three-dimensional (3D) numerical simulations made it possible to compute pulsar spin-down luminosity from first principles and revealed that oblique pulsar winds are more powerful than aligned ones. However, what causes this enhanced power output of oblique pulsars is not understood. In this work, using time-dependent 3D magnetohydrodynamic and force-free simulations, we show that, contrary to the standard paradigm, the open magnetic flux, which carries the energy away from the pulsar, is laterally non-uniform. We argue that this non-uniformity is the primary reason for the increased luminosity of oblique pulsars. To demonstrate this, we construct simple analytic descriptions of aligned and orthogonal pulsar winds and combine them to obtain an accurate 3D description of the pulsar wind for any obliquity. Our approach describes both the warped magnetospheric current sheet and the smooth variation of pulsar wind properties outside of it. We find that the jump in magnetic field components across the current sheet decreases with increasing obliquity, which could be a mechanism that reduces dissipation in near-orthogonal pulsars. Our analytical description of the pulsar wind can be used for constructing models of pulsar gamma-ray emission, pulsarwind nebulae, neutron star powered ultra-luminous X-ray sources, and magnetar-powered core-collapse gamma-ray bursts and supernovae.
AB - Rotating neutron stars, or pulsars and magnetars, are plausibly the source of power behind many astrophysical systems, such as gamma-ray bursts, supernovae, pulsar wind nebulae, and supernova remnants. In the past several years, three-dimensional (3D) numerical simulations made it possible to compute pulsar spin-down luminosity from first principles and revealed that oblique pulsar winds are more powerful than aligned ones. However, what causes this enhanced power output of oblique pulsars is not understood. In this work, using time-dependent 3D magnetohydrodynamic and force-free simulations, we show that, contrary to the standard paradigm, the open magnetic flux, which carries the energy away from the pulsar, is laterally non-uniform. We argue that this non-uniformity is the primary reason for the increased luminosity of oblique pulsars. To demonstrate this, we construct simple analytic descriptions of aligned and orthogonal pulsar winds and combine them to obtain an accurate 3D description of the pulsar wind for any obliquity. Our approach describes both the warped magnetospheric current sheet and the smooth variation of pulsar wind properties outside of it. We find that the jump in magnetic field components across the current sheet decreases with increasing obliquity, which could be a mechanism that reduces dissipation in near-orthogonal pulsars. Our analytical description of the pulsar wind can be used for constructing models of pulsar gamma-ray emission, pulsarwind nebulae, neutron star powered ultra-luminous X-ray sources, and magnetar-powered core-collapse gamma-ray bursts and supernovae.
KW - General-stars
KW - MHD-stars
KW - Magnetars-stars
KW - Magnetic field-stars
KW - Neutron-pulsars
KW - Rotation
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U2 - 10.1093/mnras/stv2869
DO - 10.1093/mnras/stv2869
M3 - Article
AN - SCOPUS:84976875270
SN - 0035-8711
VL - 457
SP - 3384
EP - 3395
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
M1 - stw127
ER -