Black Hole Growth in the Early Universe

Study supermassive black holes during the first ~1-5 billion years of cosmic history

Reveal the connections between black holes and the early galaxy population

Gain experience analysing multiwavelength astronomical survey data

Project Code CSE-PHYS2-AIRD
Level PhD
Supervisory Team Dr James Aird, Prof Mike Watson and Prof Alison Coil
Expected Start Date 24th September 2018


Supermassive black holes, with masses of millions to billions of times the mass of the Sun, are now thought to lurk at the centres of most, if not all, galaxies. We know that the bulk of the growth of these black holes occurs by the accretion of gas – producing an Active Galactic Nucleus or AGN – and that the majority this growth took place in the first ~1 – 5 billion years of cosmic history.

However, it is still unclear what physical processes drive this early growth, how the black hole growth is related to and has an impact on the early growth of galaxies, and how the seeds from which these massive black holes grow initially formed in the very early Universe.

This project will focus on identifying AGN in the early Universe, studying the properties of the galaxies they lie in, and developing models to describe the co-evolution of galaxies and their central black holes that can be extended to the very earliest cosmic times. We will take advantage of a number of state-of-the-art spectroscopic surveys – including the MOSDEF survey (a major 49-night programme with the 10m Keck telescope), a completed 9-night Keck programme that focused on early AGN (carried out in collaboration with the University of California–San Diego), and the 3DHST survey (carried out with the Hubble Space Telescope).

We will use these surveys to identify AGN and determine their properties (such as their luminosities, black hole accretion rates, and their level of obscuration) and compare these measurements with other multiwavelength diagnostics (including X-ray and infrared techniques). We will then study how the properties of the AGN depend on the types of galaxies they are found in, providing new insights into the processes fuelling and regulating black hole growth in the early galaxy population.  Finally, these results will be used to develop a model relating AGN and their host galaxies that can be extrapolated out to very early cosmic times to make predictions for future missions and observatories – in particular focusing on the Athena observatory, the next large X-ray mission under-development by the European Space Agency with a leading role by the University of Leicester.


The project will use data from the premier extragalactic survey fields that have been the subject of substantial multiwavelength imaging and spectroscopic programmes with world-leading facilities including the Hubble Space Telescope, Chandra X-ray telescope and Keck observatory. The student will construct samples of galaxies using deep optical/near-infrared imaging and then identify AGNs within these galaxy samples using the spectroscopy as well as X-ray and infrared diagnostics.  A key task will be developing techniques to account for observational biases in the different datasets. This work will then be used to determine the incidence of AGNs and the corresponding distribution of black hole growth rates as a function of galaxy properties, accounting for the established biases in the identification techniques. Finally, these results will be used to develop an observationally motivated model relating black hole and galaxy evolution (building on Aird et al. 2013) that can be extended to the very early Universe to make predictions for the Athena observatory.

Critical Skills & Training Development:


  • Gain skills in observational astronomy using world-leading multiwavelength and spectroscopic programmes and the opportunity to engage in international teams.
  • Obtain significant experience in scientific programming and data analysis.
  • Learn new statistical analysis techniques, including the development and application of contemporary Bayesian techniques.
  • Attend postgraduate courses, skills and career development sessions, group seminars and journal clubs.


Further Reading

  1. The Formation and Evolution of Massive Black Holes - Volonteri 2012, Review for Science Special Issue
  2. Cosmic X-ray surveys of distant active galaxies: The demographics, physics, and ecology of growing supermassive black holes - Brandt & Alexander 2015, The Astronomy & Astrophysics Review,
  3. X-rays across the galaxy population – II. The distribution of AGN accretion rates as a function of stellar mass and redshift - Aird, Coil & Georgakakis 2018, MNRAS,
  4. The Hot and Energetic Universe: The formation and growth of the earliest supermassive black holes - Aird et al. 2013,


  • Astrophysics
  • Data Analysis
  • Statistics

Share this page:

Application Enquiries

For all application enquiries :

Contact Details

College of Science and Engineering
Physics Building
University of Leicester 
Tel: 0116 252 3497