Thesis Topic: Black hole accretion versus star burst episodes: what is the engine of powerful active galaxies?


Thesis Supervisor: Paola Andreani

External supervisors: Luigi Spinoglio (IAPS-INAF, Rome, Italy), Kalliopi Dasya (OBSPM, Paris-Meudon, France), Matt Malkan (UCLA, CA, USA), Miguel Pereira-Santaella (IAPS-INAF, Rome, Italy)


The recent observations of the Herschel Space Observatory have improved our view of the far-infrared emission of powerful infrared-bright local galaxies.
Herschel imaging and spectroscopic data, together with other measurements at lower and higher frequencies (including Spitzer, AKARI, ALMA and IRAM submillimeter/mm ground-based data) allow us to built the detailed continuum spectral energy distributions (SED), as well as the atomic and molecular spectra of samples of local active galaxies.

The aim of this research project is to understand the emission mechanism(s) in these active galaxies:
how much power is ultimately due to accretion onto supermassive black holes and how much is due to star formation processes ?

The work will be done in two steps:

(1) Use methods to interpret the observed multifrequency continuum SED, decomposing it into several components (stellar, active nucleus contribution, thermal dust emission from star-formation). This method allows to find the relative contribution to the energetics from the active nucleus (AGN) and the star-formation, to derive the IR luminosity due to AGN only and relate it to the mid-/far-IR line luminosity.

(2) the mid-to-far-IR atomic and molecular spectra of samples of bright and nearby active galaxies (AGNs, Ulirg and Seyfert galaxies) with the use of radiation transfer codes and photoionization models, which can provide a complete physical model of the continuum and line emission of the sources.
Up to now the IR line luminosity have been related only to the total IR luminosity, including both AGN and starburst contributions.

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