Ultra High Energy Cosmic Rays New Approach A

Ultra High Energy Cosmic Rays – New Approach A. A. Petrukhin Moscow Engineering Physics Institute Contents 1. Problems of UHECR 2. Possible solution 3. Some consequences

UHECR spectrum

Some remarks 1. From experimental point of view UHECR spectrum is the EAS spectrum, but not the primary CR spectrum! 2. There are no models which can explain the slopes of spectrum unambiguously. 3. All models of CR origin have upper limitations of accelerated energies. 4. 16 years ago very interesting model was presented at International conference on plasma physics in New Delhi, 1989.

Model of CR acceleration in plasma pinches – 1 B. A. Trubnikov, V. P. Vlasov, S. K. Zhdanov Kurchatov Institute, Moscow Int. Conf. on Plasma Physics, New Delhi, India, 1989, v. 1, p. 257. The main idea of this model is the following. In cosmic plasma (of any origin) electrical discharges – "cosmic lightnings" can occur, at which cylindrical pinches are formed, similar to laboratory ones. Two basic instabilities of plasma pinches are known: snaky and neck.

Model of CR acceleration in plasma pinches – 2 Snaky Neck Plasma jets are squeezed out of pinch neck. These jets are accelerated particle beams.

Model of CR acceleration in plasma pinches – 3 It was shown that energy distribution of particles in jets has the following form: which does not depend on pinch sizes, currents in pinches and other parameters. These parameters determine a proportionality coefficient only.

Model of CR acceleration in plasma pinches – 4 F In the model the well-known equations of plasma physics are used only. F Model has no free parameters except for absolute intensity. F Model predicts for the energy spectrum slope the unambiguous value = 2. 73 F Model has no limitation for accelerated particle energy since in plasma pinch neck density , when its radius r 0

Correlation between contribution of pinch and other models into CR spectrum – 1 Two possible limiting cases: 1. The pinch mechanism dominates. For example, even at SN explosion particles are accelerated mainly in plasma pinches. 2. The contribution of pinch mechanism is small at low energies (below the knee), but can be remarkable at higher energies (f. e. above the ankle).

Pinch mechanism dominates above the ankle only

Cut-off influence – 1

Pinch mechanism dominates

Possible explanation One can suppose that massive short-lived particles (as resonance states of matter) are produced in Pe. V cosmic ray interactions (Te. V energies in the center-of-mass system). (Analogy the "island of stability" which is expected in transuranium physics around Z = 114). These particles will decay with production of W and Z-bosons, which in their turn decay into hadrons (on average 20 hadrons, mainly pions) 70% and leptons (e, e ), ( , ) 30%.

Consequences for CR energy spectrum Calculations show that at decays of W±, Z 0 -bosons with Pe. V energies, leptons must have very large energies Production of three types of VHE neutrinos: νe, νµ, ντ and VHE muons gives a missing energy, since the energy of these particles is not measured by existing EAS arrays. This missing energy can explain the knee appearance.

Missing energy

How to explain the ankle appearance? F If to explain the knee by inclusion of new particles (states of matter) which decay into leptons (directly or through W and Z 0 -bosons), F then the ankle will correspond to critical energy for new particles at which probabilities of interaction and decay are equal. At higher energies, new particles mostly interact and missing energy disappears.

Cut-off influence-2 ?

Conclusions 1. Of course the best way for solving of UHECR spectrum problem is the solution of the knee problem. 2. Independently on the knee problem the detailed measurements of UHECR spectrum in a wide interval (at least beginning below the ankle) with a single EAS array are required. 3. In particular it would be very good to construct the central part of North site of Auger observatory with smaller distance between Cherenkov water tanks.

Other interesting consequences F The composition of accelerated particles will be the same as composition of cosmic plasma, which consists mainly of hydrogen. F Model explains the absence of point sources of cosmic rays since pinches, f. e. near Supernova, can be oriented in any direction. F At the same time, generation of particles in narrow jets in cylindrical pinches can explain the appearance of correlated particles.