Introduction to active galaxies

## Radio-loud AGNs

### 6 Outstanding Issues

# 6.1 Introduction

The active galaxy model is very attractive. Indeed, it is so attractive that it is easy to overlook the many problems that remain. We will now consider some of the outstanding questions about the origin and evolution of active galaxies, focusing on two questions: do supermassive black holes really exist? And where are active galaxies now?

OpenLearn - Introduction to active galaxies
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