Simplified Models for Photohadronic Interactions in Cosmic Accelerators
Abstract
We discuss simplified models for photo-meson production in cosmic accelerators, such as active galactic nuclei (AGNs) and gamma-ray bursts (GRBs). Our self-consistent models are directly based on the underlying physics used in the SOPHIA software and can be easily adapted if new data are included. They allow for the efficient computation of neutrino and photon spectra (from π0 decays) as a major requirement of modern time-dependent simulations of the astrophysical sources and parameter studies. In addition, the secondaries (pions and muons) are explicitly generated, a necessity if cooling processes are to be included. For the neutrino production, we include the helicity dependence of the muon decays which in fact leads to larger corrections than the details of the interaction model. The separate computation of the π0, π+, and π- fluxes allows, for instance, for flavor ratio predictions of the neutrinos at the source, which are a requirement of many tests of neutrino properties using astrophysical sources. We confirm that for charged pion generation, the often used production by the Δ(1232)-resonance is typically not the dominant process in AGNs and GRBs, and we show, for arbitrary input spectra, that the number of neutrinos are underestimated by at least a factor of two if they are obtained from the neutral-to-charged pion ratio. We compare our results for several levels of simplification using isotropic synchrotron and thermal spectra and demonstrate that they are sufficiently close to the SOPHIA software.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2010
- DOI:
- 10.1088/0004-637X/721/1/630
- arXiv:
- arXiv:1002.1310
- Bibcode:
- 2010ApJ...721..630H
- Keywords:
-
- astroparticle physics;
- elementary particles;
- galaxies: active;
- gamma-ray burst: general;
- neutrinos;
- Astrophysics - High Energy Astrophysical Phenomena;
- High Energy Physics - Phenomenology
- E-Print:
- Treatment of high energy interactions refined, additional black body benchmark added (v2), some references corrected (v3). A Mathematica notebook which illustrates the implementation of one model can be found at http://theorie.physik.uni-wuerzburg.de/~winter/Resources/AstroModel/Sim-B.html . 46 pages, 14 (color) figures, 7 tables. Final version, accepted for publication in ApJ