The role of magnetic reconnection on jet/accretion disk systems

Abstract

Context. It was proposed earlier that the relativistic ejections observed in microquasars could be produced by violent magnetic reconnection episodes at the inner disk coronal region (de Gouveia Dal Pino & Lazarian 2005). Aims. Here we revisit this model, which employs a standard accretion disk description and fast magnetic reconnection theory, and discuss the role of magnetic reconnection and associated heating and particle acceleration in different jet/disk accretion systems, namely young stellar objects (YSOs), microquasars, and active galactic nuclei (AGNs). Methods. In microquasars and AGNs, violent reconnection episodes between the magnetic field lines of the inner disk region and those that are anchored in the black hole are able to heat the coronal/disk gas and accelerate the plasma to relativistic velocities through a diffusive first-order Fermi-like process within the reconnection site that will produce intermittent relativistic ejections or plasmons.Results. The resulting power-law electron distribution is compatible with the synchrotron radio spectrum observed during the outbursts of these sources. A diagram of the magnetic energy rate released by violent reconnection as a function of the black hole (BH) mass spanning 10 9 orders of magnitude shows that the magnetic reconnection power is more than sufficient to explain the observed radio luminosities of the outbursts from microquasars to low luminous AGNs. In addition, the magnetic reconnection events cause the heating of the coronal gas, which can be conducted back to the disk to enhance its thermal soft X-ray emission as observed during outbursts in microquasars. The decay of the hard X-ray emission right after a radio flare could also be explained in this model due to the escape of relativistic electrons with the evolving jet outburst. In the case of YSOs a similar magnetic configuration can be reached that could possibly produce observed X-ray flares in some sources and provide the heating at the jet launching base, but only if violent magnetic reconnection events occur with episodic, very short-duration accretion rates which are ∼100−1000 times larger than the typical average accretion rates expected for more evolved (T Tauri) YSOs.

The 2010 VERY HIGH ENERGY Γ-Ray FLARE AND 10 YEARS OF MULTI-WAVELENGTH OBSERVATIONS OF M 87

“…The predicted exponential character of the flux increase and decay during the resulting VHE event, a flat GeV to TeV γ -ray spectrum from proton-proton interactions, as well as the accompanying X-ray flux enhancement due to the freefree emission of the shocked cloud of the stellar matter, are particularly interesting features of the model that should be kept in mind. Other scenarios could yet be considered in the same context as well, involving stochastic acceleration of highenergy particles within a turbulent accretion flow close to the event horizon of an SMBH (in analogy to the model proposed by Liu et al 2006, in the context of VHE γ -ray emission of Sgr A*), or reconnection-driven impulsive acceleration of electron-positron pairs in a magnetized corona of the accretion disk, e.g., in analogy to the model proposed by Zdziarski et al (2009) in the context of VHE observations of the Galactic X-ray binary system Cygnus X-1 (see also de Gouveia Dal Pino et al 2010).…”

The energetics of relativistic magnetic reconnection: ion-electron repartition and particle distribution hardness

“…Large scale magnetic reconnection events may be at the origin of large scale transient jets in microquasar systems (de Gouveia dal Pino & Lazarian 2005;de Gouveia Dal Pino et al 2010;Kowal et al 2011;Dexter et al 2014), for example via a magnetic field reversal accreted onto a magnetically arrested disk. Reconnection then occurs in the accretion disk coronae, near the black hole, where particle densities and magnetic fields are high.…”

“…It is a candidate for explaining (i) particle acceleration at pulsar wind termination shocks (Kirk & Skjaeraasen 2003;Pétri & Lyubarsky 2007;Sironi & Spitkovsky 2011a); (ii) the flat radio spectra from galactic nuclei and AGNs (Birk et al 2001) and from extragalactic jets (Romanova & Lovelace 1992); (iii) GeV flares from the Crab nebula (Bednarek & Idec 2011;Uzdensky et al 2011;Cerutti et al 2012aCerutti et al ,b, 2013; (iv) flares in active galactic nuclei (AGN) jets (Giannios et al 2009) or in gamma-ray bursts (Lyutikov 2006a;Lazar et al 2009); (v) the heating of AGN and microquasar coronae and the observed flares (Di Matteo 1998;Merloni & Fabian 2001;Goodman & Uzdensky 2008;Reis & Miller 2013;Romero et al 2014;Zdziarski et al 2014); (vi) the heating of the lobes of giant radio galaxies (Kronberg et al 2004); (vii) transient outflow production in microquasars and quasars (de Gouveia dal Pino & Lazarian 2005;de Gouveia Dal Pino et al 2010;Kowal et al 2011;Dexter et al 2014); (viii) gamma-ray burst outflows and non-thermal emissions (Drenkhahn & Spruit 2002;Giannios & Spruit 2007;McKinney & Uzdensky 2012); (ix) X-ray flashes (Drenkhahn & Spruit 2002); or (x) soft gamma-ray repeaters (Lyutikov 2006b;Uzdensky 2011).…”

Reconnection and particle acceleration in interacting flux ropes – II. 3D effects on test particles in magnetically dominated plasmas

“…Electrons in solar flares can reach energies up to 5 -50 MeV, while protons gain energies up to several GeV (Evenson et al 1984, Aschwanden 2002. Reconnection has also been proposed as a mechanism for powerful flares and particle acceleration in more extreme settings like pulsar wind nebulae (Michel 1982;Lyubarsky & Kirk 2001;Porth et al 2016), gamma-ray bursts (McKinney & Uzdensky 2012), magnetospheres of magnetars (Lyutikov 2003;Lyutikov 2006;Meng et al 2014;Elenbaas et al 2016) and in coronae and jets of accreting black holes and active galactic nuclei (Goodman & Uzdensky 2008;de Gouveia Dal Pino et al 2010;Wilkins et al 2015).…”