from The Open University
Alternatively you can skip the navigation by pressing 'Enter'.
OU on the BBC- Wanted: A Very Personal Assistant: Episode OneTuesday, 28th July 2015 01:30 - BBC ThreeThe first programme in this two part series sees our young disabled people interviewing potential candidates and the... Read more: OU on the BBC- Wanted: A Very Personal Assistant: Episode One
The Bank: LendingAvailable until Saturday, 8th August 2015 00:50The final episode of The Bank explore our need to borrow more money to buy anything from mortgages to plastic surgery. Read more: The Bank: Lending
OU on the BBC- Wanted: A Very Personal Assistant: Episode OneAvailable until Thursday, 27th August 2015 02:30
A History of Ideas: What is love?Available until Wednesday, 27th July 2016 00:00
The Bottom Line: Summer 2015: The Bottom Line - SupermarketsAvailable for over a year
Do any animals have consciousness?Before arguing for cephalopod consciousness, the Cephalover explores arguments for any animals... Read more: Do any animals have consciousness?
Take the photographic memory testCan you capture scenes just by looking at them? Find out with our photographic memory test. Launch now: Take the photographic memory test
Beginners’ Italian: food and drinkThis free course, Beginners’ Italian: food and drink, focuses on buying drinks and snacks in an... Try: Beginners’ Italian: food and drink now
English: skills for learningThis course is for anybody who is thinking of studying for a university degree and would like to... Try: English: skills for learning now
An overview of active galaxies
Active galaxies provide a prime example of high energy processes operating in the...
Active galaxies provide a prime example of high energy processes operating in the Universe. This unit gives an overview of active galaxies, including the supermassive black holes that power the engines at their centres, and the emission processes by which we detect and study them. It also gives practice in mathematical techniques for analysing data and theoretical models.
By the end of this unit you should be able to:
- recognise the terminology which is used to describe the properties and behaviour of active galactic nuclei (AGN);
- manipulate numbers, algebraic symbols and mathematical functions in equations.
- Current section: Introduction
- Learning outcomes
- 1 Meet your first active galactic nuclei
- 2 Black holes: a reminder
- 3 AGN reside at the centres of galaxies
- 4 Black holes at the centres of ordinary galaxies
- 5 Distances in extragalactic astronomy
- 6 The key questions
- 7 Continuum emission processes
- 7.1 Blackbody radiation
- 7.2 Free-free radiation
- 7.3 Polarization of electromagnetic radiation
- 7.4 Faraday depolarization
- 7.5 Emission from spiralling electrons: synchrotron radiation
- 7.6 Producing synchroton radiation in a laboratory
- 7.7 Radiation detection
- 7.8 Example 2 and questions
- 7.9 Compton scattering
- 8 Basic properties and historical perspective
- 9 Summary
Study this free course
Enrol to access the full course, get recognition for the skills you learn and track your progress. Make your learning visible!
An overview of active galaxies
This unit begins by studying evidence leading to our basic hypothesis that active galactic nuclei (AGN) are accreting, supermassive black holes. It also covers some physics of radiation which you will need to be able to interpret the observed emission of AGN, and includes an examination of AGN.
You will be studying a young subject and there are fundamental issues which are still being vigorously debated by the experts and are subject to current research activity. Consequently, it is not possible to give clear definitive explanations of all aspects of the subject.
You may already have become accustomed to reading unfamiliar words and phrases. In this unit, you will not only encounter new and specialised vocabulary, you will meet ideas which are currently being shaped and tested. Do not be dismayed if you fail to immediately grasp the underlying principles behind some of the material you will read: it is possible no-one has yet elucidated them!
This unit is from our archive and is an adapted extract from The energetic universe (S381) which is no longer taught by The Open University. If you want to study formally with us, you may wish to explore other courses we offer in.
This is an extract from an Open University course which is no longer available to new students. If you found this interesting you could explore more free Physics and Astronomy courses or view the range of currently available OU Physics and Astronomy courses.
Copyright & revisions
Originally published: Tuesday, 19th April 2011
- Creative-Commons: The Open University is proud to release this free course under a Creative Commons licence. However, any third-party materials featured within it are used with permission and are not ours to give away. These materials are not subject to the Creative Commons licence. See terms and conditions. Full details can be found in the Acknowledgements section.
- This site has Copy Reuse Tracking enabled - see our FAQs for more information.
If you enjoyed this, why not follow a feed to find out when we have new things like it? Choose an RSS feed from the list below. (Don't know what to do with RSS feeds?)
Remember, you can also make your own, personal feed by combining tags from around OpenLearn.