TY - JOUR
T1 - Ab-initio Pulsar Magnetosphere
T2 - Particle Acceleration in Oblique Rotators and High-energy Emission Modeling
AU - Philippov, Alexander A.
AU - Spitkovsky, Anatoly
N1 - Funding Information:
The simulations presented in this article used computational resources supported by the PICSciE-OIT High Performance Computing Center and Visualization Laboratory and by NASA/Ames HEC Program (SMD-16-6663, SMD-16-7816).
Funding Information:
We thank Jonathan Arons, Andrei Beloborodov, Vasily Beskin, Samuel Gralla, Benoit̂ Cerutti, Andrei Gruzinov, Alexander Tchekhovskoy, and Andrey Timokhin for fruitful discussions. This research was supported by the NASA Earth and Space Science Fellowship Program (grant NNX15AT50H to A.P.), a Porter Ogden Jacobus Fellowship awarded by Princeton University to A.P., NASA through Einstein Postdoctoral Fellowship awarded by the Chandra X-ray Center to A.P. (grant number PF7-180165), which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060, NASA grant NNX15AM30G, and the Simons Foundation (grant 267233 to A.S.), and was facilitated by the Max Planck/Princeton Center for Plasma Physics. The simulations presented in this article used computational resources supported by the PICSciE-OIT High Performance Computing Center and Visualization Laboratory and by NASA/Ames HEC Program (SMD-16-6663, SMD-16-7816).
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/3/10
Y1 - 2018/3/10
N2 - We perform global particle-in-cell simulations of pulsar magnetospheres, including pair production, ion extraction from the surface, frame-dragging corrections, and high-energy photon emission and propagation. In the case of oblique rotators, the effects of general relativity increase the fraction of the open field lines that support active pair discharge. We find that the plasma density and particle energy flux in the pulsar wind are highly non-uniform with latitude. A significant fraction of the outgoing particle energy flux is carried by energetic ions, which are extracted from the stellar surface. Their energies may extend up to a large fraction of the open field line voltage, making them interesting candidates for ultra-high-energy cosmic rays. We show that pulsar gamma-ray radiation is dominated by synchrotron emission, produced by particles that are energized by relativistic magnetic reconnection close to the Y-point and in the equatorial current sheet. In most cases, the calculated light curves contain two strong peaks, which is in general agreement with Fermi observations. The radiative efficiency decreases with increasing pulsar inclination and increasing efficiency of pair production in the current sheet, which explains the observed scatter in L γ versus . We find that the high-frequency cutoff in the spectra is regulated by the pair-loading of the current sheet. Our findings lay the foundation for quantitative interpretation of Fermi observations of gamma-ray pulsars.
AB - We perform global particle-in-cell simulations of pulsar magnetospheres, including pair production, ion extraction from the surface, frame-dragging corrections, and high-energy photon emission and propagation. In the case of oblique rotators, the effects of general relativity increase the fraction of the open field lines that support active pair discharge. We find that the plasma density and particle energy flux in the pulsar wind are highly non-uniform with latitude. A significant fraction of the outgoing particle energy flux is carried by energetic ions, which are extracted from the stellar surface. Their energies may extend up to a large fraction of the open field line voltage, making them interesting candidates for ultra-high-energy cosmic rays. We show that pulsar gamma-ray radiation is dominated by synchrotron emission, produced by particles that are energized by relativistic magnetic reconnection close to the Y-point and in the equatorial current sheet. In most cases, the calculated light curves contain two strong peaks, which is in general agreement with Fermi observations. The radiative efficiency decreases with increasing pulsar inclination and increasing efficiency of pair production in the current sheet, which explains the observed scatter in L γ versus . We find that the high-frequency cutoff in the spectra is regulated by the pair-loading of the current sheet. Our findings lay the foundation for quantitative interpretation of Fermi observations of gamma-ray pulsars.
KW - plasmas
KW - pulsars: general
KW - stars: magnetic field
KW - stars: rotation
UR - http://www.scopus.com/inward/record.url?scp=85044050024&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85044050024&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aaabbc
DO - 10.3847/1538-4357/aaabbc
M3 - Article
AN - SCOPUS:85044050024
SN - 0004-637X
VL - 855
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 94
ER -