Reconnection-driven plasmoids in blazars: fast flares on a slow envelope

By D. Giannios. 2012

168 citations recorded by the source corpus.

Minute-timescale TeV flares have been observed in several blazars. The fast flaring requires compact regions in the jet that boost their emission towards the observer at an extreme Doppler factor of delta>50. For TeV photons to avoid annihilation in the broad line region of PKS 1222+216, the flares must come from large (pc) scales challenging most models proposed to explain them. Here we elaborate on the magnetic reconnection minijet model for the blazar flaring, focusing on the inherently time-dependent aspects of the process of magnetic reconnection. I argue that, for the physical conditions prevailing in blazar jets, the reconnection layer fragments leading to the formation a large number of plasmoids. Occasionally a plasmoid grows to become a large, "monster" plasmoid. I show that radiation emitted from the reconnection event can account for the observed "envelope" of ~ day-long blazar activity while radiation from monster plasmoids can power the fastest TeV flares. The model is applied to several blazars with observed fast flaring. The inferred distance of the dissipation zone from the black hole and the typical size of the reconnection regions are R_diss~0.3-1 pc and l' \simless 10^{16} cm, respectively. The required magnetization of the jet at this distance is modest: sigma ~a few. Such dissipation distance R_diss and reconnection size l' are expected if the jet contains field structures with size of the order of the black-hole horizon.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/98c4521da9257777bd7f6533f9045dc3ce3ea762

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Citations in the corpus

Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection (2016, background): “Such ‘minijets’ could represent outflow regions from relativistic reconnection sites (Giannios et al. 2009; Nalewajko et al. 2011), with local values of σi several times larger than the mean.”
Relativistic Jets Shine through Shocks or Magnetic Reconnection (2015, background): “…by relativistic motions, with outflow Lorentz factorsΓout ∼ √ σ as measured in the rest frame of the jet (Lyubarsky 2005), which has profound implications for jet variability(e.g., Lyutikov & Blandford 2003; Giannios et al. 2009; Nalewajko et al. 2011; Narayan & Piran 2012; Giannios 2013).”
Plasmoids in relativistic reconnection, from birth to adulthood: first they grow, then they go (2016, background): “…& Lyubarsky 2007; Sironi & Spitkovsky 2011a), jets from active galactic nuclei (AGNs; e.g.,Romanova & Lovelace 1992; Giannios et al. 2009, 2010; Giannios 2013) and gamma-ray bursts (GRBs; e.g.,Thompson 1994, 2006; Usov 1994; Spruit et al. 2001; Drenkhahn & Spruit 2002; Lyutikov & Blandford…”
RELATIVISTIC RECONNECTION: AN EFFICIENT SOURCE OF NON-THERMAL PARTICLES (2014, background): “…& 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 (GRBs; Thompson 1994, 2006; Spruit et al. 2001; Lyutikov & Blandford 2003; Giannios 2008).”
SIMULATIONS OF PARTICLE ACCELERATION BEYOND THE CLASSICAL SYNCHROTRON BURNOFF LIMIT IN MAGNETIC RECONNECTION: AN EXPLANATION OF THE CRAB FLARES (2013, background): “Relativistic bulk outflows with Lorentz factor of order Γ ∼ √σ = 4 are expected in relativistic Petschek reconnection (Lyubarsky 2005), and lead to a Doppler amplification of the observed emission (Giannios et al. 2009, 2010; Nalewajko et al. 2011; Clausen-Brown & Lyutikov 2012; Giannios 2013).”