Issue |
A&A
Volume 581, September 2015
|
|
---|---|---|
Article Number | A18 | |
Number of page(s) | 12 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201525972 | |
Published online | 26 August 2015 |
Variation of bulk Lorentz factor in AGN jets due to Compton rocket in a complex photon field
Institut de Planétologie et d’Astrophysique de Grenoble, 414 rue de la Piscine, 38400 St.-Martin d’Hères France
e-mail: thomas.vuillaume@obs.ujf-grenoble.fr
Received: 26 February 2015
Accepted: 30 June 2015
Radio-loud active galactic nuclei are among the most powerful objects in the universe. In these objects, most of the emission comes from relativistic jets getting their power from the accretion of matter ontosupermassive black holes. However, despite the number of studies, a jet’s acceleration to relativistic speeds is still poorly understood. It is widely known that jets contain relativistic particles that emit radiation through several physical processes, one of them being the inverse Compton scattering of photons coming from external sources. In the case of a plasma composed of electrons and positrons continuously heated by the turbulence, inverse Compton scattering can lead to relativistic bulk motions through the Compton rocket effect. We investigate this process and compute the resulting bulk Lorentz factor in the complex photon field of an AGN composed of several external photon sources. We consider various sources:the accretion disk, the dusty torus, and the broad line region. We take their geometry and anisotropy carefully into account in order to numerically compute the bulk Lorentz factor of the jet at every altitude. The study, made for a broad range of parameters, shows interesting and unexpected behaviors of the bulk Lorentz factor, exhibiting acceleration and deceleration zones in the jet. We investigate the patterns of the bulk Lorentz factor along the jet depending on the source sizes and on the observation angle and we finally show that these patterns can induce variability in the AGN emission with timescales going from hours to months.
Key words: galaxies: jets / galaxies: active / radio continuum: galaxies / radiation mechanisms: non-thermal / scattering / plasmas
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.