The TALES doctorate network in a nutshell

The offered PhD position is part of the TALES (Time-domain Analysis to study the Life-cycle and Evolution of Supermassive black holes) Doctorate Network, a consortium of 10 astrophysics research groups, 8 industrial and 4 academic partners spread across Europe that aims to study the feeding and feedback cycle of supermassive black holes. The TALES doctorate candidates will (i) leverage time-domain astronomy observations from state-of-the-art facilities to map the inner environments of supermassive black holes, (ii) use novel analysis methods from the discipline of data science to maximise the information gain from the observations and (iii) develop new theories and models to interpret the data and learn about the physics of the life-cycle of black holes at the centres of galaxies. Parallel to the core research activities above, TALES aspires to implement an ambitious training programme on both technical and complementary skills that is tailored to the needs of the doctorate candidates and includes secondments to industrial and/or academic partners as well as specialised lectures and science communication events. 

The Specific Doctoral Project:

It is currently thought that most massive galaxies in the Universe host in their nuclear regions black holes that are million or even billion times more massive than our Sun. These exotic astrophysical objects are thought to grow their masses over long periods of time by swallowing gaseous matter from their immediate environments. During this process an accretion disk is formed that funnels the material onto the black hole, thereby feeding it and increasing its mass. The infall of matter onto the compact object via the accretion disk is also accompanied by the release of huge amounts of energy that can be observed at various parts of the electromagnetic spectrum with characteristic signatures that define the population of Active Galactic Nuclei (AGN).

Understanding in detail the physics of the accretion process onto supermassive black holes remains a major challenge of current astrophysical research and one of the central objectives of the TALES Doctorate Network. Recently, it has been realised that temporal information may hold the key for understanding the inner structure and physics of accretion flows. This is based on the fact that the accretion process is by nature highly dynamic, i.e. ever changing with time, which observationally translates to a “flickering” of the emitted flux at any wavelength, i.e. continuous variations with time around a mean value. By studying the variability timescales of AGN at different wavelengths we learn about the geometry of the different energy emitting components of the accretion flow (e.g. accretion disk, X-ray corona, outflows). Moreover, the simultaneous modelling of the variability amplitudes at different wavebands and timescales provides physical information on the dynamics of the accretion flow and the interplay between its different components.   

This project intends to provide a comprehensive characterisation of the variability properties of large (type-I and type-II) AGN samples using long-term monitoring surveys, such as GAIA, ZTF, VST, CRTS and the upcoming EUCLID and LSST, to study the accretion disk properties,  constrain the dependence of the observed UV/optical variability on black hole mass, Eddington ratio, line-of-sight obscuration and redshift, and use these results to test the unification model. The project also intends to exploit variability as a means for finding AGN in the context of  demographic studies. The project will use forward-modelling time-series simulations to assess observational biases such as irregular sampling, as well as explore novel approaches such as diffeomorphic transformations for deriving unbiased UV/optical time-lags and variability measurements. Further development will allow the combination with X-ray data provided by other nodes of the network in order to study the link between the disk and the corona in the context of physically motivated semi-empirical models.

The doctoral candidate will be based at the Department of Physics “Ettore Pancini” of the Federico II University in Naples, Italy, and will be supervised by Prof. Maurizio Paolillo. The doctoral candidate will enrol in the PhD programme at the Federico II University of Naples, starting in fall 2025 (usually October/November). Foreseen secondments include the INAF-Astrophysical Observatory of Torino (INAF/OATO),  the University of Crete (UOC)  and industrial partners of the TALES Doctorate Network.