Nonthermal flaring of cosmic objects: Modelling photon and particle radiation
Final Report Abstract
We modeled photon and particle radiation in flares from cosmic sources ranging from solar particle events to compact extragalactic photon sources, especially active galactic nuclei, by solving time-dependent transport equations of photons and energetic charged particles (cosmic rays) which, although in different cosmic environments, have similar mathematical structure. The radiation modelling of synchroton-self-Compton (SSC) photons additionally requires the inclusion of propagation and retardation effects of the generated nonthermal photons. The transport of solar energetic charged particles along the interplanetary magnetic field in the ecliptic plane of the sun can be described roughly by a one-dimensional diffusion equation. Large-scale spatial variations of the guide magnetic field can be taken into account by adding an additional term to the diffusion equation that includes the effect of adiabatic focusing. By revisiting the quasilinear transport theory of cosmic rays in partially turbulent magnetic fields we related the transport parameters of the diffusion equation to the power spectra of the turbulent magnetic fields. The transport theory is general enough that it can also be applied to the transport and acceleration of charged dust grains in MHD turbulence and to the diffusive acceleration of cosmic rays at cosmic shock waves of arbitrary speed. For solar particle events we solved the cosmic ray transport equation analytically by assuming a point-like particle injection in time and space and a spatial power-law dependence for the focusing length and the spatial diffusion coefficient. The resulting intensity- and anisotropy-time profiles of solar energetic particles compare favorably well with the 27-512 keV electron intensities and anisotropies observed by the Wind spacecraft during the exceptionally large solar energetic particle event on 2001 April 15. For flares from active galactic nuclei the energy spectra and light curves of relativistic hadrons and electrons resulting from the conversion of relativistic bulk motion by the relativistic pick-up process were calculated. The relativistic electron and hadron distributions were used to calculate high-energy photon and neutrino energy spectra and light curves from accelerated hadrons and electrons in these objects. In doing so, characteristic features of flaring blazars are obtained with respect to causality and retardation effects between the generated photons inside and at the edge of the emission cloud. On the one hand, there are frequency dependent time lags indicating the underlying emission scenario that also enable to determine the time slot of a corresponding neutrino signal at the observer. On the other hand, the consequences on the spectral energy distributions due to non-linear SSC cooling indicate that external photon sources are no longer needed to account for a dominating inverse-Compton peak. Finally, the energy spectra and light curves are compared with observations of PKS 2155-305, 3C 279 and 3C 454.3 from TeV-gamma ray telescopes showing a quite good agreement of theory and observation.
Publications
- A diffusive description for the focused transport of solar energetic particles: Intensity- and anisotropy-time profiles as a powerful diagnostic tool for interplanetary particle transport conditions, Astron. Astrophys. 535 (2011) A92
Artmann, S., Schlickeiser, R., Agueda, N., Krucker, S. and Lin, R. P.
(See online at https://dx.doi.org/10.1051/0004-6361/201117885) - A new cosmic ray transport theory in partially turbulent space plasmas: Extending the quasilinear approach, Astrophys. J. 732 (2011) 96
Schlickeiser, R.
(See online at https://dx.doi.org/10.1088/0004-637X/732/2/96) - Focused acceleration of cosmic-ray particles in non-uniform magnetic fields, Astrophys. J. 732 (2011) L31
Litvinenko, Y. E. and Schlickeiser, R.
(See online at https://doi.org/10.1088/2041-8205/732/2/L31) - A new ordering parameter of spectral energy distributions from synchrotron-self-Compton emitting blazars, Mon. Not. R. Astr. 420 (2012) 84
Zacharias. M. and Schlickeiser, R.
(See online at https://doi.org/10.1111/j.1365-2966.2011.20004.x) - Cosmic ray transport theory in partially turbulent space plasmas with compressible magnetic turbulence, Astrophys. J. 745 (2012) 153
Casanova, S., Schlickeiser, R.
(See online at https://doi.org/10.1088/0004-637X/745/2/153) - Differences of leptonic and hadronic radiation production in flaring blazars, Astrophys. J. 749 (2012) 155
Eichmann, E., Schlickeiser, R and Rhode, W.
(See online at https://doi.org/10.1088/0004-637X/749/2/155) - External Compton emission in blazars of nonlinear synchrotron self-Compton-cooled electrons, Astrophys. J. 761 (2012) 110
Zacharias. M. and Schlickeiser, R.
(See online at https://doi.org/10.1088/0004-637X/761/2/110) - On the duration of blazar synchrotron flares, Astrophys. J. 744 (2012) 153
Eichmann, E., Schlickeiser, R and Rhode, W.
(See online at https://doi.org/10.1088/0004-637X/744/2/153) - Synchrotron lightcurves of blazars in a time-dependent synchrotronself Compton cooling scenario, Astrophys. J. 777 (2013) 109
Zacharias, M. and Schlickeiser, R.
(See online at https://doi.org/10.1088/0004-637X/777/2/109) - The telegraph equation for cosmic-ray transport with weak focusing, Astron. Astrophys. 554 (2013) A59
Litvinenko, Y. E. and Schlickeiser, R.
(See online at https://doi.org/10.1051/0004-6361/201321327)
