Fate of baby radio galaxies: Dead or Alive ?

Abstract

In order to reveal the long-term evolution of relativistic jets in active galactic nuclei (AGNs), we examine the dynamical evolution of variously-sized radio galaxies [i.e., compact symmetric objects (CSOs), medium-size symmetric objects (MSOs), Fanaroff-Riley type II radio galaxies (FRIIs)]. By comparing the observed relation between the hot spot size and the linear size of radio source with a coevolution model of hot spot and cocoon, we find that the advance speed of hot spots and lobes inevitably show the deceleration phase (CSO-MSO phase) and the acceleration phase (MSO-FRII phase). The deceleration is caused by the growth of the cross-sectional area of the cocoon head. Moreover, by comparing the hot spot speed with the sound speed of the ambient medium, we predict that only CSOs whose initial advance speed is higher than 0.3-0.5c can evolve into FRIIs.

5 pages and 3 figures, accepted for publication in Astronomische Nachrichten (issue dedicated to the Proceedings of "The 4th Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources" held at Riccione, Italy, 26-29 May 2008)

References in corpus (7)

• Fast outflows in compact radio sources: evidence for AGN-induced feedback in the early stages of radio source evolution
• A numerical simulation of the evolution and fate of a FRI jet. The case of 3C 31
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• The Kinematic and Spectral Ages of the Compact Radio Source CTD 93
• On the dynamical evolution of hot spots in powerful radio loud AGNs
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Cited by in corpus (2)

• The Dynamic Evolution of Young Extragalactic Radio Sources
• Radio Source Evolution on Galactic Scales