Questions raised at the workshop

Throughout the week, the wide range of talks, posters, and discussions raised a number of exciting and important outstanding questions. We plan to address many of the key outsanding issues in the review of the workshop to appear in New Astronomy Reviews.

Input from participants with regards to the questions below (or suggestions for additional issues to consider) would be very valuable. If you would like to offer your perspective on any of these issues, please send us an email at, or fill in the form below. Any and all contributions would be very much appreciated.

Some key unresolved issues:

1. How can we link the various spatial scales (e.g., <1pc; 1-100pc; 1kpc)? Are the observations and models on those different scales consistent? How well do we understand shock physics? What are the limitations in the simulations? [session 1: "physics"]

2. How do quasars turn off? Do they stay off? Can we define evolutionary tracks in the M-mdot plane? Many outbursts? Always Eddington limited? Is radio loud a phase or different object population? Can we use X-ray binaries to help address these questions or are there issues? [session 1: "physics"]

3. Why is the dark-matter halo mass of ~10^12-10^13 solar masses important for the switching on of AGN/quasar activity? How much black-hole growth is determined by halo mass? [session 2: "surveys"]

4. What is balance between merger and secular evolution? How can black holes grow in satellite versus central galaxies? [session 2: "surveys"]

5. How important were "radio" and "quasar" modes at z~2 when the most massive galaxies probably had their star-formation activity switched off? Down to what radio powers is gas heating by radio jets important? What, if anything, can we agree that we actually know about AGN feedback? Do we understand the physics of quasar versus radio mode feedback? [sessions 2 and 4: "surveys" and "feedback"]

6. Can we uncover the seed-mass distribution? [session 3: "quasars"]

7. What can we believe in black-hole masses? How can we improve measurements? Where is the evidence for black holes of 10^5 solar masses in galaxies? [session 3: "quasars"]

Responses to these questions

Participants are encouraged to send us their input on these (or any other) questions raised at the workshop, or to send us any additional issues we may have missed. You can send your responses by email to, or by filling in the form below.


What Drives the Growth of Black Holes?
Durham University
26 - 29 July 2010

Scientific Organising Committee
D. Alexander
R. Hickox
P. Best
R. Davies
T. di Matteo
A. Fabian
J. Greene
M. Volonteri

Local Organising Committee
L. Borrero
K. Coppin
A. Danielson
J. Geach
A. Goulding
J. Mullaney

Last Updated: 6 June 2011

Banner Image: courtesy of NASA