PhD Studentship: Probing the co-evolution of super-massive black holes and their host galaxies via

Engineering & the Environment

Location: Highfield Campus

Closing Date:  Wednesday 20 December 2017

Reference: 820916F2

Project Reference: NGCM - 0091.

Supermassive black holes, extreme singularities of spacetime, of the order of a million to a billion solar masses, are lurking in the cores of most galaxies, including our own Milky Way.

The masses of supermassive black holes seem to be tightly correlated with several host galaxy properties, such as bulge stellar mass and the characteristic random motions (“velocity dispersion”) of stars. This is remarkable, because the bulge mass and velocity dispersion are measured on scales 100 to 1000 times larger than the gravitational sphere of influence of the black hole. The very existence of these correlations suggests a close “co-evolution” between black holes and their host galaxies.

In Shankar et al. (2016), awarded a press release from the Royal Astronomical Society, the supervisor showed that the correlation between black hole mass and velocity dispersion is the fundamental one, with all other apparent correlations being driven by this intrinsic one, coupled to observational selection biases.

This discovery strongly favours “quasar-feedback” models, which naturally predict a tight correlation with velocity dispersion, over merger-driven models of black hole growth which would instead predict a tight correlation with stellar mass. In the first class of models, supermassive black holes are in fact believed to have powered quasars in their past, and to have played a key role in controlling galaxy growth through powerful winds/jets.

This paradigm-shift breakthrough has put in serious doubt the results of the research carried out until now, which has been based, incorrectly, on cosmological models tuned against the highly biased correlation with stellar mass.

The novelty of this project will be: 1) the specific use of velocity dispersions to calibrate the growth and feedback of black holes in galaxies; 2) a cutting-edge

combination of state-of-the-art cosmological galaxy formation models coupled with high-resolution numerical simulations for obtaining accurate estimates of galaxy dynamics (velocity dispersion).

This project aims at determining the relative roles of quasar feedback and galaxy mergers in setting the scaling relations with velocity dispersion, and, in turn, constraining the radiative efficiency (and thus the spin) of black holes. This project will also set very stringent constraints on the gravitational wave background, of capital importance for the next gravitational wave detectors (eLISA).

The prospective student will be expected to ideally have enhanced programming skills and, to a lower extent, some background training in astrophysics. The student will become part of the next-generation European space galaxy missions, Euclid and Athena.

If you wish to discuss any details of the project informally, please contact Francesco Shankar, Email: F.Shankar@soton.ac.uk, Tel: +44 (0) 2380 592150

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

Further details:

• Job Description and Person Specification