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Inside the Commons - Episode 4Saturday, 28th February 2015 21:15 - BBC Two Scotland onlyIn the final part of Inside the Commons, battles break out over the future of the House. Read more: OU on the BBC: Inside the Commons - Episode 4
Wartime Farm Episode 1Sunday, 1st March 2015 08:00 - Yesterday
Wartime Farm Episode 2Sunday, 1st March 2015 08:30 - Yesterday
Thinking Allowed: Migration to London and South AfricaMonday, 2nd March 2015 00:15 - BBC Radio 4
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OU on the BBC: Inside the CommonsThis major four-part series from inside the House Of Commons gives viewers unparalleled access to... Read more: OU on the BBC: Inside the Commons
Succeed with maths – Part 1 [TEST]DO NOT ATTEMPT TO COMPLETE THIS COURSE. IT IS ENTIRELY FOR OPENLEARN TESTING PURPOSES. Try: Succeed with maths – Part 1 [TEST] now
Succeed with maths – Part 1[BETA] If you feel that maths is a mystery that you want to unravel then this short 8-week course... Try: Succeed with maths – Part 1 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
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 course units or view the range of currently available OU Physics and Astronomy courses.