2005/04/08 by S. Sahayanathan, Ranjeev Misra, R. Misra
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/430812
published as Astrophys.J. 628 (2005) 611-616 · Accepted for publication in Astrophysical Journal
arxiv created 2005/04/08 · openalex publication_date 2005/07/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
The dynamics of relativistically moving blobs ejected out of a central AGN are considered. It is assumed that the collision between two blobs is completely inelastic, such that the bulk kinetic energy lost in the collision is used to energize electrons to relativistic energies via acceleration in internal shocks that are formed by the collision. These high-energy electrons, which are produced on a timescale corresponding to the collision timescale, cool by radiative losses due to synchrotron and inverse Compton processes. The model is applied to the radio/X-ray knots of several AGNs. For three of these sources we have analyzed long (>40 ks) Chandra observations and report on constraints on the X-ray spectral indices. In the framework of this model the AGNs are inferred to sporadically eject relativistic blobs on timescales ranging from 10 11 to 10 12 s for different sources. It is shown that the collision timescales can be longer than the age of the knot, and hence nonthermal electrons are continuously being injected into the system. This continuous injection, in contrast to an instantaneous one-time injection, gives rise to a characteristic spectral break rather than a high-energy cutoff in the spectrum.