Electron-positron pair production by ultrarelativistic electrons in a soft photon field

Abstract. The double and single differential cross-sections with respect to positron and electron energies as well as the total cross-section of triplet production in the laboratory frame are calculated numerically in order to develop a Monte Carlo code for modelling electron-photon cascades in a soft photon field. To avoid numerical integration irregularities of the integrands, which are inherent to problems of this type, we have used suitable substitutions in combination with a modern powerful program code (Mathematica) allowing one to achieve reliable higher-precission results. The results obtained for the total cross-section closely agree with others estimated analytically or by a different numerical approach. The results for the double and single differential cross-sections turn out to be somewhat different from some reported recently. The mean energy of the produced particles, as a function of the characteristic collisional parameter (the electron rest frame photon energy), is calculated and approximated by an analytical expression that revises other known approximations over a wide range of values of the argument. The primary-electron energy loss rate due to triplet pair production is shown to prevail over the inverse Compton scattering loss rate at several (∼2) orders of magnitude higher interaction energy than that predicted formerly.

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“…This fact has been recently emphasized and confirmed by incorporating TPP into full cascade calculations [2]- [5].…”

Section: Introductionmentioning

confidence: 67%

“…Therefore, based on equations (13)- (15) we can write the following analytical expression of L T P P normalized to the quantity χ = cnπr [2], Dermer and Schlickeiser [9] and Feenberg and Primakoff [10], respectively.…”

Section: Primary-electron Energy Lossesmentioning

confidence: 99%

On the numerical analysis of triplet pair production cross-sections and the mean energy of produced particles for modelling electron-photon cascade in a soft photon field

Anguelov

Petrov

Gurdev

et al. 1999

J. Phys. G: Nucl. Part. Phys.

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“…Modelling of proton synchrotron radiation (3) was done in a manner analogous to electron synchrotron. Triplet pair production (10) was modelled according to (Mastichiadis et al 1986;Mastichiadis 1991). However, the basic improvement of the present paper is for photopion production (2).…”

Section: Setup Of the Problemmentioning

confidence: 99%

The time-dependent one-zone hadronic model

Dimitrakoudis

Mastichiadis

Protheroe

et al. 2012

A&A

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We present a time-dependent approach to the one-zone hadronic model in the case where the photon spectrum is produced by ultrarelativistic protons interacting with soft photons that are produced from protons and low magnetic fields. Assuming that protons are injected at a certain rate in a homogeneous spherical volume containing a magnetic field, the evolution of the system can be described by five coupled kinetic equations, for protons, electrons, photons, neutrons, and neutrinos. Photopair and photopion interactions are modelled using the results of Monte-Carlo simulations and, in particular, from the SOPHIA code for the latter. The coupling of energy losses and injection introduces a self-consistency in our approach and allows the study of the comparative relevancy of processes at various conditions, the efficiency of the conversion of proton luminosity to radiation, the resulting neutrino spectra, and the effects of time variability on proton injection, among other topics. We present some characteristic examples of the temporal behaviour of the system and show that this can be very different from the one exhibited by leptonic models. Furthermore, we argue that, contrary to the wide-held belief, there are parameter regimes where the hadronic models can become quite efficient. However, to keep the free parameters at a minimum and facilitate an in-depth study of the system, we have only concentrated on the case where protons are injected; i.e., we did not consider the effects of a co-accelerated leptonic component.

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“…The production mechanisms of electron-positron pairs have been investigated by many authors in connection with astrophysical problems (e.g., Bisnovatyi-Kogan et al 1971;Lightman 1982;Svensson 1982Svensson , 1984. In particular, the pair production arising from the interaction of photons with the Coulomb field of electrons e-mail: haug@tat.physik.uni-tuebingen.de or positrons (γ−e pair production, triplet production) has been studied by Zdziarski (1985), Mastichiadis et al (1986Mastichiadis et al ( , 1994, Mastichiadis (1991), and Dermer & Schlickeiser (1991), mostly in connection with electron energy losses by triplet pair production in photon fields. The threshold for γ−e pair production in the rest system of the electrons is (hν) t = 4mc 2 ≈ 2 MeV.…”

Section: Introductionmentioning

confidence: 99%