On the efficiency of particle acceleration by rotating magnetospheres in AGN

¹ Dipartimento di Fisica Generale, Universitá degli Studi di Torino, via Pietro Giuria 1, Torino 10125, Italy e-mail: osmanov@to.infn.it
² Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium e-mail: Andria.Rogava@wis.kuleuven.be
³ Abdus Salam International Centre for Theoretical Physics, Trieste 34014, Italy e-mail: arogava@ictp.it
⁴ Osservatorio Astronomico di Torino, Strada dell'Osservatorio 20, 10025 Pino Torinese, Italy e-mail: bodo@to.astro.it

Received: 13 June 2006
Accepted: 15 January 2007

Abstract

Aims.To investigate the efficiency of centrifugal acceleration of particles as a possible mechanism for the generation of ultra-high γ-ray nonthermal emission from TeV blazars, we study the centrifugal acceleration of electrons by rotating magnetic field lines, for an extended range of inclination angles and determine the maximum Lorentz factors attainable by the electrons via this process.

Methods.Two principal limiting mechanisms for the particle acceleration, inverse Compton scattering and breakdown of the bead-on-the-wire approximation, are examined.

Results.Particles may be centrifugally accelerated up to 10⁸ and the main limiting mechanism for the is the inverse Compton scattering.

Conclusions.The energy of centrifugally accelerated particles can be amply sufficient for the generation (via inverse Compton scattering) of the ultra-high energy (up to 20 TeV) gamma emission in TeV blazars.