Powerful radio galaxies have played a central role in our understanding of active galaxies over the past five decades. Cygnus-A, the brightest and most nearby FR-II source, has been a Rosetta Stone in this study. It appears to have the outward characteristics of a normal radio galaxy but it.s proximity allows us to identify the more subtle properties of an obscured quasar. The energy provided by this very active galaxy is sufficient to launch the energetic jets we observe but the transport of the energy to the hotspots is poorly constrained and understood. The growing realisation that AGN directly affect their host galaxy through a direct feedback mechanism throughout the lifetime of the galaxy makes it especially important for the most nearby obscured quasar to be observed with the widest possible spectral coverage. We propose to use Herschel to reveal the heating of the central region and the energetics of the hotspots. We request observations of the atomic cooling lines [OI], [OIII] and [CII] that will allow us to compare the energetics of the ISM in Cygnus A with other local and more distant galaxies.
Publication
Infrared colours and spectral energy distributions of hard X-ray selected obscured and Compton-thick active galactic nuclei . Kilerci Eser Ece et al. . Monthly Notices of the Royal Astronomical Society . null . null . 2020MNRAS.494.5793K , L‧CO/LFIR Relations with CO Rotational Ladders of Galaxies Across the Herschel SPIRE Archive . Kamenetzky J. et al. . The Astrophysical Journal, Volume 829, Issue 2, article id. 93, 16 pp. (2016). . 829 . 10.3847\/0004-637X\/829\/2\/93 . 2016ApJ...829...93K ,
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
European Space Agency, 2012, A Definitive Herschel Study Of The Most Powerful Local Radio Galaxy - Cygnus A, SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-jxwcjqk
