Reconnection in Marginally Collisionless Accretion Disk Coronae

Abstract

We point out that a conventional construction placed on observations of accreting black holes, in which their nonthermal X-ray spectra are produced by inverse Comptonization in a coronal plasma, suggests that the plasma is marginally collisionless. Recent developments in plasma physics indicate that fast reconnection takes place only in collisionless plasmas. As has recently been suggested for the Sun's corona, such marginal states may result from a combination of energy balance and the requirements of fast magnetic reconnection.

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

“…The threshold where Compton drag against these photons is significant can be reached in the inner parts of microquasar coronae if n e is not too high (as given by Eq. (A.10)) (see also Goodman & Uzdensky 2008).…”

“…For example, reconnection in a microquasar corona close to the hole and in the γ-ray emitting region of an extragalactic jet takes place with the same magnetizations (Table 5) and thus features the same reconnection rate, particle spectra, or energy distribution, even if magnetic field strengths differ by six orders of magnitude (provided, however, that the geometry is the same). This is true as long as reconnection occurs in the collisionless regime, an issue discussed, for example, by Goodman & Uzdensky (2008) and Ji & Daughton (2011). Also, it requires that effects such as radiative braking by emission or Compton drag, or pair annihilations, do not perturb the reconnection physics.…”

“…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).…”

Relativistic magnetic reconnection in collisionless ion-electron plasmas explored with particle-in-cell simulations

“…Such attributes made it attractive for high-energy astrophysics to explain, for example, radiation (Romanova & Lovelace 1992) and flares (Giannios et al 2009) in active galactic nuclei (AGNs) jets or in gamma-ray bursts (Lyutikov 2006a;Lazar et al 2009), the heating of AGN and microquasar coronae and associated flares (Di Matteo 1998;Merloni & Fabian 2001;Goodman & Uzdensky 2008;Reis & Miller 2013), the flat radio spectra from galactic nuclei and AGNs (Birk et al 2001), the heating of the lobes of giant radio galaxies (Kronberg et al 2004), the σ-paradox and particle acceleration at pulsar wind termination shocks (Kirk & Skjaeraasen 2003;Pétri & Lyubarsky 2007;Sironi & Spitkovsky 2011), GeV flares from the Crab nebula (Cerutti et al 2012a(Cerutti et al ,b, 2013, 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), gamma-ray burst outflows and non-thermal emissions (Drenkhahn & Spruit 2002;McKinney & Uzdensky 2012), X-ray flashes (Drenkhahn & Spruit 2002), soft gamma-ray repeaters (Lyutikov 2006b;Uzdensky 2011), flares in double pulsar systems (Lyutikov & Lazarian 2013), or energy extraction in the ergosphere of black holes (Koide & Arai 2008).…”

Table-top solar flares produced with laser driven magnetic reconnections

“…Magnetic reconnection (MR) is a fundamental physical process in a plasma which facilitates the conversion of magnetic energy into kinetic and thermal energies through acceleration and/or heating of particles [11,12], and is believed to dominate among different astrophysical phenomena from solar flares [13,14], star formations [15], other astrophysical events [16], laser-produced plasma jets [17][18][19], tokamak sawteeth [20] to disruptions in laboratories. Considerably large scale differences between astrophysical and laboratory plasmas hinder the direct measurements of magnetic reconnection events in laboratory.…”