Project Ref: NGCM-0081
Supervisor: Professor Christian Knigge
Academic Unit: Physics & Astronomy
Research Group: Astronomy
Co-supervisor: Dr Sebastian Hoenig
Research Area: Other
Project Description: Quasars are the most luminous steady sources in the observable universe. Their power is provided by a remarkable central engine: a super-massive black hole that is surrounded and fed by a luminous accretion disk. Surprisingly, the inflow of material through the disk onto the black hole appears to be accompanied by powerful outflows in the form of disk winds. Approximately 15% of all quasars exhibit clear evidence for such disk winds, in the form of broad, blue-shifted absorption lines. However, these so-called 'broad absorption line quasars' are just the tip of the iceberg: since disk-driven winds cannot be spherical, these objects are probably just the sub-set of quasars viewed at a particularly favourable orientation. In reality, all quasars are likely to drive such winds.
This is important for two reasons. First, it suggests that disk winds may provide a simple unification scenario, in which the observational diversity of quasars is primarily due to the range of viewing angles from which we observe them. Second, disk winds can remove significant amounts of mass, energy and angular momentum from the quasar and inject it into the surrounding (inter-)galactic medium. This provides a natural way for the the black hole to affect its host galaxy on large scales. Such 'feedback' is required to explain the otherwise mysterious co-evolution of supermassive black holes and their host galaxies (such as the strong correlation between the mass of the black hole and that of its host).
However, despite their importance, we know almost nothing about these accretion disk winds. For example, their geometry, kinematics, and even the basic driving mechanism responsible for launching them are still basically unknown. The aim of this project is to remedy this situation through state-of-the-art computational modelling. More specifically, we will use an advanced and unique Monte Carlo ionization and radiative transfer code to predict the observational signatures produced by these outflows. In addition, we will couple our radiative transfer code to a full hydrodynamics code, which will allows to self-consistently model disk winds driven by radiation pressure in spectral lines for the very first time.
If you wish to discuss any details of the project informally, please contact Professor Christian Knigge, Astronomy Research Group, Email: C.Knigge@soton.ac.uk, Tel: +44 (0) 2380 593 955.
Keywords: Computational Astrophysics, Computational Modelling, Fluid Dynamics, Astrophysics
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