Speaker
Description
The jets produced by accretion onto super-massive black holes inflate into cocoons of shocked plasma (radio galaxies). While a majority of such sources have an active galactic nucleus, the central activity in a small fraction of radio galaxies switches off, giving rise to a dying radio galaxy. This talk presents the results of Quici et al. (in prep), which identifies a complete sample of active and dying radio galaxies using MWA, ASKAP and ATCA radio data. We discuss the challenges associated with identifying complete samples of dying radio galaxies. By considering the energetics (between ~100 MHz and 10 GHz), we present supporting evidence that dying radio galaxies fade rapidly once the AGN switches off. We constrain the fraction of dying radio galaxies, in a flux limited sample, between 6% and 12% and discuss the potential implications of these values in terms of the radio-loud AGN duty cycle. We present a peculiar dying radio galaxy candidate in which the morphology of the radio emission is in some tension with its spectral energy distribution, and discuss the possible evolutionary scenarios. Finally we discuss how complete samples of radio galaxies, such as that used for this study, can be used to probe the duty cycle of radio-loud AGN.
| Suggested presentation duration (minutes) | 15-20 |
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