This project aims at solving still unanswered issues and break long-standing degeneracies in current, traditional models of galaxy evolution, by unveiling the evolutionary processes shaping galaxies, and their associated super-massive black holes (BHs). Consequently, this proposed research aims at considerably advancing our proper understanding of structure formation in the Universe. Massive BHs of the order of million to billion solar masses have been detected at the centre of all types of local galaxies. Their masses appear to be well correlated with the large-scale properties of the galaxies they live in, especially in bulge-dominated/spheroidal galaxies. Bulges, and their associated BHs, can be formed in a variety of erratically different processes, from heavy sequences of mergers, to others mainly based on in-situ star formation, and/or more or less violent disc instabilities. Current, state-of-the-art galaxy evolution models still present strong degeneracies despite reproducing similar observables. One of the causes behind such degeneracies is the high number of parameters and uncertain recipes adopted to describe baryon physics. Given the still controversial theoretical picture available on the evolution of (especially bulged) galaxies and their central BHs, a devoted, comprehensive study on this subject is mandatory. To this purpose our advanced semi-empirical model (SEM) of galaxy evolution will be used. The SEM, by design, avoids adopting any of the (often contrasting!) heavily parameterized approaches usually followed in traditional models to describe the still poorly understood physics of baryonic cooling, star formation, and feedback. This approach effectively removes the “burden’’ of constructing full, ab-initio galaxy evolution models. This is achieved by empirically assigning galaxies to dark matter haloes, in a way to match the observed galaxy number densities and spatial distribution. The SEM uses observables (e.g., stellar mass function) as inputs, rather than outputs as in current models. This allows the focus on other (highly debated) issues related to galaxy evolution, such as the true role of mergers or disc instabilities.
A central seed BH is then assigned to each central galaxy at the time of initialization. BH growth can then be triggered via galaxy mergers, and/or other “in-situ” triggering mechanisms, more importantly, disc instabilities, radiation drag, and stellar winds.
Clear, detailed, and simultaneous predictions will be made for the optical/X-ray BH luminosity functions, their clustering properties at all scales, the BH mass function at all cosmic epochs, the evolution of the BH spin (important for future gravitational wave detectors), and extrapolations to high redshifts to probe the still highly debated population of seed BHs (fundamental for, e.g., LOFAR, SKA).
While the modelling of BHs in a cosmological context has already been proposed in the literature, it was never performed before onto a refined semi-empirical galaxy evolution model such as ours that, by construction, already satisfies all the basic statistical, structural, and spectral host galaxy properties.
“Mock’’ galaxy catalogues will be also be made available from this research project. This is one of the primary objectives of our group as members of one of next largest ESA’s space mission, Euclid (scheduled for 2020).
If you wish to discuss any details of the project informally, please contact Dr. Francesco Shankar, Physics&Astronomy research group, Email: [email protected]
, Tel: +44 (0) 2380 59 2150.
This project is run through participation in the EPSRC Centre for Doctoral Training in Next Generation Computational Modelling (http://ngcm.soton.ac.uk). For details of our 4 Year PhD programme, please see http://www.findaphd.com/search/PhDDetails.aspx?CAID=331&LID=2652
For a details of available projects click here http://www.ngcm.soton.ac.uk/projects/index.html
Visit our Postgraduate Research Opportunities Afternoon to find out more about Postgraduate Research study within the Faculty of Engineering and the Environment: http://www.southampton.ac.uk/engineering/news/events/2016/02/03-discover-your-future.page