Dissipation of jet bulk kinetic energy in powerful blazars

Free access article

Issue		A&A Volume 463, Number 2, February IV 2007


Page(s)		529 - 537
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20066448

A&A 463, 529-537 (2007)
DOI: 10.1051/0004-6361:20066448

Dissipation of jet bulk kinetic energy in powerful blazars

K. Katarzynski^{1, 2} and G. Ghisellini¹

¹ Osservatorio Astronomico di Brera, via Bianchi 46, Merate and via Brera 28, Milano, Italy
e-mail: kat@astro.uni.torun.pl
² Torun Centre for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87100 Torun, Poland

(Received 26 September 2006 / Accepted 20 October 2006)

Abstract
Aims. We investigate the dissipation of the bulk kinetic energy of a relativistic jet at different distances from the central power-house and analyse in detail how the dissipated energy is radiated away.
Methods. We assume that the location of the dissipation region is a function of the bulk Lorentz factor $\Gamma$ of the jet, being closer to the centre for smaller $\Gamma$ . This assumption is naturally fulfilled in the internal shock scenario. The dissipated energy is partially used to accelerate electrons and to amplify the magnetic field. This process creates a source inside the jet (blob). Such blobs may efficiently produce synchrotron and inverse Compton emission.
Results. We find that even if the blobs or shells responsible for the blazar activity carry the same energy (in bulk kinetic form), the fact that they move at different $\Gamma$ can produce dramatic variations in different bands, even if the bolometric luminosity is instead very similar. This is due to the relative importance of the synchrotron, self-Compton, and external Compton radiation processes, which greatly change by changing $\Gamma$ and the compactness of the source, even if the total radiated energy is constant. We then find that the jet can produce most of its radiative output at small distances from the putative black hole and its accretion disk, this implies a low level of emitted MeV-GeV flux. Our findings, which we apply for illustrative purposes to the blazar 3C 454.3, will be easily testable by the coming $\gamma$ -ray satellite, such as AGILE and GLAST.

Key words: radiation mechanisms: non-thermal -- galaxies: active -- BL Lacertae objects: individual: 3C 454.3

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.