Rationale

Rationale

         Active galactic nuclei (AGN) play an important role in many aspects of modern cosmology. They are fundamental for understanding galaxy formation and evolution, black hole formation and growth, and the connection between the two. Multiwavelength studies by Herschel, ALMA, Planck, NuSTAR, HST and more, combined with larger and deeper AGN samples, resulted in better understanding of nuclear activity in galaxies and AGN physics across cosmic time. This improvement is the result of: better AGN selection methods and better understanding of AGN properties at all wavelengths; more precise measurements of star formation rates (SFR) and the connection between star formation (SF) and AGN activity; better testing of AGN unification; better understanding of the interplay between AGN and their host galaxies, and AGN triggering mechanisms; better measurements of supermassive black hole (SMBH) properties; observations and numerical simulation of AGN feedback; detection of AGN at higher and higher redshift, and their use as cosmological laboratories, etc. However, we are still far from understanding the full physics behind AGN activity and their role in galaxy formation and evolution.

        With this conference we would like to achieve two main goals. First, we want to provide a general overview of recent findings and progress in observations, simulations, and theory of AGN from the local universe up to high redshifts. This includes the following questions:

1. What have we learnt from AGN multiwavelength studies and what can we expect from future instruments such as eROSITA, JWST, Euclid, CTA, SKA, E-ELT, Athena, etc.?
2. What is the current status of the unification model of AGN? What are the components distinguishing type-1 and type-2 AGN?
3. What do we know about AGN host galaxies? What is the effect of AGN on their host galaxy and how important is AGN feedback compared with stellar feedback in the context of preserving (or not) SMBH scaling relationships at low and high redshift?
4. What is the status of AGN theory and numerical simulations regarding AGN triggering, including mergers and secular processes, AGN disks, AGN outflows and the shutting off of AGN activity?
5. How well we understand the origin of jets and their impact on galaxy evolution? What evidences do we have for AGN positive and negative feedback across cosmic time? In what kind of environments AGN reside?
6. How precisely can we measure BH mass at different redshifts?
7. What are the properties of highest-redshift AGN? What do we know about AGN evolution?

The timing is appropriate since we are now witnessing a strong growth of results for large data-sets at all wavelengths, and since we need to define the right questions to answer with the new missions.

Secondly, with this conference we want to bring for the first time world experts in our field to the East-African region and contribute to the development of science in Ethiopia and Africa, which is very much needed. We want to call the attention of the international scientific community to the new activities and development of astrophysics in Sub-Saharan countries. For most of the international community South Africa is still the major player regarding scientific activities in astronomy and space science in Africa. However, over the recent past years many other countries have begun research activities, opened new MSc and PhD programs at their universities (e.g., Uganda, Rwanda, Ethiopia, Kenya, Madagascar, Ghana, Sudan, Nigeria, etc.), and started from scratch with developing new research centers and technological facilities (e.g., SKA-African members) for improving their socio-economical challenges. Many achievements have been realized, but still there are many difficulties, challenges, and needs. In the same line, the Ethiopian Space Science and Technology Institute (ESSTI) is a new research center established under the Ministry of Science and Technology. It is the first center of such kind in Ethiopia and one of the first in all East-African region. Organizing this international conference in Ethiopia will be an important contribution and a sign of international support to this new development of science in the country and Africa and important motivation for African scientists and students, by covering the state-of-the-art in AGN physics as a whole, which is an important sub-discipline in astrophysics. To take a maximum advantage of this meeting a training for undergraduate, MSc and PhD students will be organized before the conference (see the details in the program outline below). After the conference we will organise a training for secondary school teachers under the Network for Astronomy School Education (NASE). To promote science in general among the public and school children, one afternoon will be dedicated to the public talk and interaction between the conference participants and visitors (see below for more details). The last activities will be done in collaboration with the Ethiopian Space Science Society (ESSS) and Addis Ababa University (AAU). Through both we will give more visibility to this event and attract the attention of the general public, school children, teachers, and students. Finally, we will have two lunch sessions for all interested participants to discuss about: ‘The development of astronomy and space science in Africa’ and ‘The status of women in astronomy and space science in Africa’.

            In summary, we hope that this conference will improve our understanding of nuclear activity in galaxies across cosmic time. We aim at clarifying the role of nuclear activity in the broader context of galaxy evolution, outlining major unsolved problems and observational and theoretical strategies to solve them. In addition, we aim at strengthening the development of science in Ethiopia and Africa and opening new space for collaborations between Africa and other parts of the globe for the benefit of all.