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Paper: Accretion and Jet Activities in Young Radio Galaxies
Volume: 446, Galaxy Evolution: Infrared to Millimeter Wavelength Perspective
Page: 161
Authors: Wu, Q.
Abstract: We estimate the black hole (BH) mass and bolometric luminosity for a sample of young radio galaxies [gigahertz-peaked spectrum (GPS) and compact steep-spectrum (CSS) sources]. We find that the average BH mass of these young radio galaxies <log Mbh> ≅ 8.3, which is less than that of radio loud QSOs and low redshift radio galaxies (<log Mbh> ≅ 9.0). The CSS/GPS sources have relatively high Eddington ratios with average ratio <log Lbol/LEdd>= –0.56, which are similar to those of narrow line Seyfert 1 galaxies (NLS1s). The smaller BH mass and higher accretion rate of CSS/GPS sources suggest that they may not only be in the early stage of radio activities, but also in the early stage of their accretion activities. We find that the ages are positively correlated with the bolometric luminosities for a sample of young radio galaxies with estimated ages, which is consistent with theoretical prediction based on radiation pressure instability of accretion disk in Czerny et al. The ages of young radio galaxies are also found to be consistent with the theoretical durations of outbursts in BH mass and accretion rate (in Eddington unit) plane, where the outbursts are assumed to be triggered by the radiation pressure instabilities. Our results provide the observational evidence for the radiation pressure instability, which causes limit-cycle behavior, as a physical mechanism that may be responsible for these short-lived young radio galaxies.
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