On the Origin of Ultra High Energy Cosmic Rays II

Abstract

We show that accretion disks around Active Galactic Nuclei (AGN's) could account for the enormous power in observed ultra high energy cosmic rays ≈ 10 20 eV (UHE's). In our model, cosmic rays are produced by quasi-steady acceleration of ions in magnetic structures previously proposed to explain jets around Active Galactic Nuclei (AGN's) with supermassive black holes. Steady acceleration requires that an AGN accretion disk act as a dynamo, which we show to follow from a modified Standard Model in which the magnetic torque of the dynamo replaces viscosity as the dominant mechanism accounting for angular momentum conservation during accretion. A black hole of mass M BH produces a steady dynamo voltage V ∝ √M BH giving V ≈ 10 20 volts for M BH ≈ 10 8 solar masses. The voltage V reappears as an inductive electric field at the advancing nose of a dynamo-driven jet, where plasma instability inherent in collisionless runaway acceleration allows ions to be steadily accelerated to energies ≈ V, finally ejected as cosmic rays. Transient events can produce much higher energies. The predicted disk radiation is similar to the Standard Model. Unique predictions concern the remarkable collimation of jets and emissions from the jet/radiolobe structure. Given M BH and the accretion rate, the model makes 7 predictions roughly consistent with data: (1) the jet length; (2) the jet radius; (3) the steady-state cosmic ray energy spectrum; (4) the maximum energy in this spectrum; (5) the UHE cosmic ray intensity on Earth; (6) electron synchrotron wavelengths; and (7) the power in synchrotron radiation. These qualitative successes motivate new computer simulations, experiments and data analysis to provide a quantitative verification of the model.

Sustained Spheromak Physics Experiment (SSPX): design and physics results

“…volume of plasma and magnetic field. The SSPX results have helped guide an ongoing study of cosmic rays formed via jets emanating from black holes, with the basic MHD physics of the effect similar to those seen in early time injection studies in the experiment [72].…”

Quasi-Static Model of Magnetically Collimated Jets and Radio Lobes. Ii. Jet Structure and Stability

“…Then the current I will fall until it goes below the minimum required for jet ejection. This would eventually interrupt the current, which would soon be restarted, altogether causing the central column current I to hover at equipartition, confirmed by numerical solutions in Fowler et al (2009a). The same would hold if current were disrupted along the jet, replenished by a "virtual anode" that would form at the point of rupture.…”

“…We can approximate an anode sheath at a location z = d as a Child-Langmuir sheath (Goldston & Rutherford 1995), modified to account for gravity. The modified Poisson's equation has the following form (Fowler et al 2009a):…”