The Termination Shock in a Striped Pulsar Wind

By J. Pétri, Y. Lyubarsky. 2003

177 citations recorded by the source corpus.

Most of the rotational luminosity of a pulsar is carried away by a relativistic magnetized wind in which the matter energy flux is negligible compared to the Poynting flux. However, observations indicate that most of the Poynting flux is eventually converted into ultra‐relativistic particles. The mechanism responsible for this transformation remains poorly understood. Near the equatorial plane of an obliquely rotating pulsar magnetosphere, the magnetic field reverses polarity with the pulsar period, forming a wind with oppositely directed field lines and called a striped wind.We study the conditions required for magnetic energy release at the termination shock of the striped pulsar wind. Magnetic reconnection is considered via analytical methods and 1D relativistic PIC simulations. An analytical condition on the upstream parameters for partial and full magnetic reconnection is derived from the conservation laws of energy, momentum and particle number density across the relativistic shock. Furthermore, by using a 1D relativistic PIC code, we study in detail the reconnection process at the termination shock for different upstream Lorentz factors and magnetizations, and find good agreement with our analytical criterion. Thus, alternating magnetic fields annihilate easily at relativistic highly magnetized shocks. We apply our criterion for dissipation to deduce bounds on the pair multiplicity, κ, in the pulsar wind.Most of the rotational luminosity of a pulsar is carried away by a relativistic magnetized wind in which the matter energy flux is negligible compared to the Poynting flux. However, observations indicate that most of the Poynting flux is eventually converted into ultra‐relativistic particles. The mechanism responsible for this transformation remains poorly understood. Near the equatorial plane of an obliquely rotating pulsar magnetosphere, the magnetic field reverses polarity with the pulsar period, forming a wind with oppositely directed field lines and called a striped wind.We study the conditions required for magnetic energy release at the termination shock of the striped pulsar wind. Magnetic reconnection is considered via analytical methods and 1D relativistic PIC simulations. An analytical condition on the upstream parameters for partial and full magnetic reconnection is derived from the conservation laws of energy, momentum and particle number density across the relativistic shock. Furthermore, by ...

Subfields: Astronomy and Astrophysics, Geophysics

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THE MAXIMUM ENERGY OF ACCELERATED PARTICLES IN RELATIVISTIC COLLISIONLESS SHOCKS (2013, background): “…the conclusion that particle acceleration along extended X-lines formed by tearing of the current sheets may contribute to the flat particle distribution (with spectral index p ' 1.5) required to explain the far infrared and radio spectra of PWNe (e.g., Lyubarsky 2003; Sironi & Spitkovsky 2011a).”
Plasmoids in relativistic reconnection, from birth to adulthood: first they grow, then they go (2016, background): “…via magnetic reconnection has been often invoked to explain the non-thermal signatures of pulsar wind nebulae (PWNe; e.g.,Lyubarsky & Kirk 2001; Lyubarsky 2003; Kirk & Skjæraasen 2003; Pétri & Lyubarsky 2007; Sironi & Spitkovsky 2011a), jets from active galactic nuclei (AGNs; e.g.,Romanova &…”
PARTICLE ACCELERATION IN RELATIVISTIC MAGNETIZED COLLISIONLESS PAIR SHOCKS: DEPENDENCE OF SHOCK ACCELERATION ON MAGNETIC OBLIQUITY (2009, background): “21 Alternatively, magnetic reconnection of the striped wind field when compressed at the termination shock may be responsible for particle energization (Pétri & Lyubarsky 2007; Lyubarsky & Liverts 2008).”
Synchrotron nebulae created by anisotropic magnetized pulsar winds (2004, background): “In Komissarov & Lyubarsky (2003) we briefly described the results of the first ever such study.”
Relativistic Shocks: Particle Acceleration and Magnetization (2015, background): “…that particle acceleration along extended X-lines formed by tearing of the current sheets may contribute to the flat particle distribution (with spectral index sγ ' 1.5) required to explain the far infrared and radio spectra of PWNe (e.g. , Lyubarsky 2003; Sironi and Spitkovsky 2011a, 2012).”
EFFICIENCY OF MAGNETIC TO KINETIC ENERGY CONVERSION IN A MONOPOLE MAGNETOSPHERE (2009, background): “More recently, Pétri & Lyubarsky (2007) have shown that magnetic reconnection of the warped equatorial current sheet may occur right at the wind termination shock, leading to a decrease in the inferred pre-shock wind magnetization.”
RELATIVISTIC RECONNECTION: AN EFFICIENT SOURCE OF NON-THERMAL PARTICLES (2014, background): “…particles required to explain the non-thermal signatures of pulsar wind nebulae (PWNe; Lyubarsky & Kirk 2001; Lyubarsky 2003; Kirk & Skjæraasen 2003; Pétri & Lyubarsky 2007), jets from active galactic nuclei (AGNs; Romanova & Lovelace 1992; Giannios et al. 2009; Giannios 2013) and gammaray bursts…”
Three-dimensional magnetohydrodynamic simulations of the Crab nebula (2013, background): “In order to check these ideas and study the 2D models in details, a number of groups carried out axisymmetric relativistic MHD simulations of pulsar wind nebulae (Komissarov & Lyubarsky 2003, 2004; Del Zanna, Amato & Bucciantini 2004; Bogovalov et al. 2005).”
The Proto-Magnetar Model for Gamma-Ray Bursts (2010, background): “…either indirectly by refreshing the forward shock (e.g. Granot & Kumar 2006; Dall’Osso et al. 2010) or directly (‘internally’) by e.g. forced reconnection at the forward shell (e.g. Lyubarsky 2003, 2005; Thompson 2006; Zhang & Yan 2011) or by upscattering forward shock photons (Panaitescu 2008).”
SIMULATIONS OF PARTICLE ACCELERATION BEYOND THE CLASSICAL SYNCHROTRON BURNOFF LIMIT IN MAGNETIC RECONNECTION: AN EXPLANATION OF THE CRAB FLARES (2013, background): “…simulations (Zenitani & Hoshino 2001, 2007, 2008; Jaroschek et al. 2004b; Bessho & Bhattacharjee 2007, 2012; Daughton & Karimabadi 2007; Pétri & Lyubarsky 2007; Lyubarsky & Liverts 2008; Yin et al. 2008; Jaroschek & Hoshino 2009; Liu et al. 2011; Sironi & Spitkovsky 2011; Kagan et al.…”
Gamma-ray binaries and related systems (2013, background): “The termination shock provides such reconnection sites if the pulsar wind remains striped: compression of the magnetic field at the shock can then trigger reconnection (Lyubarsky 2003).”
On the relativistic magnetic reconnection (2005, background): “In pulsars, the relativistic magnetic reconnection was proposed as a source of the high-energy emission (Lyubarskii 1996; Kirk, Skjæraasen & Gallant 2002) and as the solution to the σ-problem (Coroniti 1990; Lyubarsky & Kirk 2001; Kirk & Skjæraasen 2003; Lyubarsky 2003).”
The physics of gamma-ray bursts & relativistic jets (2014, background): “…reconnection and particle acceleration (e.g. Zenitani and Hoshino, 2001, 2007, 2008; Jaroschek et al., 2004; Bessho and Bhattacharjee, 2007, 2012; Pétri and Lyubarsky, 2007; Liu et al., 2011; Sironi and Spitkovsky, 2011, 2012; Kagan et al., 2013) — see Zweibel and Yamada (2009) for a more…”
GAMMA-RAY ACTIVITY IN THE CRAB NEBULA: THE EXCEPTIONAL FLARE OF 2011 APRIL (2011, background): “One alternative is that magnetic reconnection in the striped pulsar wind might accelerate particles (Lyubarsky 2003; Kirk 2004; Yuan et al. 2011; Bednarek et al. 2011).”
Pulsar Wind Nebulae as Cosmic Pevatrons: A Current Sheet’s Tale (2012, background): “…within the TWS is of possible importance if the upstream magnetic stripes do survive all the way to the TWS, for then reconnection, driven by the shock induced increase in the pressure, can dissipate the oppositely directed stripes of magnetic field (Lyubarsky 2003; Sironi and Spitkovsky 2011).”
The Astrophysics of Ultrahigh-Energy Cosmic Rays (2011, background): “…of high energy particles in solar flares, has been applied to UHECR acceleration in pulsar winds (Coroniti 1990; Lyubarsky & Kirk 2001), in newborn millisecond pulsars (de Gouveia Dal Pino & Lazarian 2000), in termination shocks of pulsar winds (Lyubarsky 2003), and in GRB outflows (Thompson 2006).”
ACCELERATION OF PARTICLES AT THE TERMINATION SHOCK OF A RELATIVISTIC STRIPED WIND (2011, methodology): “To explain the radio through optical emission of the Crab, the power law of lsironi@astro.princeton.edu; anatoly@astro.princeton.edu shock-accelerated electrons should span at least three decades in particle energy (e.g., Lyubarsky 2003).”