The Fate of Young Radio Galaxies: Decelerations Inside Host Galaxies?

Abstract

We examine the 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 relation between the hot spot size and the projected linear size with a coevolution model of hot spots and a cocoon. We take account of the deceleration effect by the cocoon head growth. 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). This is ascribed to the change of the power-law index of ambient density profile in the MSO phase ($\sim$1 kpc). It is also found that the cocoon shape becomes nearly spherical or disrupted for MSOs, while an elongated morphology is predicted for CSOs and FRIIs. This seems to be consistent with the higher fraction of distorted morphology of MSOs than that of CSOs and FRI. Finally, we predict that only CSOs whose initial advance speed is higher than about 0.1c can evolve into FRIIs, comparing the hot spot speed with the sound speed of the ambient medium.

12 pages, 8 figures, 4 tables, accepted for publication in ApJ; Table 1 and Table 2 are available at http://yso.mtk.nao.ac.jp/~kawakatu/Kawakatu08.pdf

References in corpus (10)

• A numerical simulation of the evolution and fate of a FRI jet. The case of 3C 31
• In search of dying radio sources in the local universe
• The impact of radio feedback from active galactic nuclei in cosmological simulations: Formation of disk galaxies
• Constraining the nature of High Frequency Peakers. I. The spectral variability
• Tracing jet--ISM interaction in young AGN: correlations between [OIII] 5007 and 5-GHz emission
• The Kinematic and Spectral Ages of the Compact Radio Source CTD 93
• On the dynamical evolution of hot spots in powerful radio loud AGNs
• Extragalactic MeV gamma-ray emission from cocoons of young radio galaxies
• Inverse-Compton emission from the lobes of 3C353
• Seven-frequency VLBI observations of the GHz-Peaked-Spectrum source OQ 208

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• The radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 in a galaxy merger
• Relationship between the [OIII] 5007 line and 5GHz radio emission
• Identifying compact symmetric objects with high-precision VLBI and Gaia astrometry
• Fate of baby radio galaxies: Dead or Alive ?
• High energy emission from AGN cocoons in clusters of galaxies
• AGN hosting jets. I: A semi-analytical model for the evolution of radio galaxies