Module Catalogue 2024/25

Pre Requisite Comment

N/A

Co Requisite Comment

N/A

Aims

The aim of this course is to develop the theory of radiation and its interaction with matter in order to understand the physical processes involved in the formation of the spectrum. We will use this framework to explore a range of astrophysical systems including: planetary nebulae, stars, supernova remnants, black holes in binary systems and active galactic nuclei, and galaxy clusters. Theoretical models for the spectrum and other observational properties of these systems will be derived, critically examined, and used to measure physical properties of the system from observables such as spectral lines.

Outline Of Syllabus

- Radiation field: radiative flux, solid angle, intensity, Planck function.
- Radiative transfer: optical depth, source function, equation of radiative transfer.
- Spectral lines: emission and absorption lines, excitation and de-excitation mechanisms, statistical equilibrium.
- Ionization and re-combination: mechanisms, ionization balance, HII regions.
- Basic stellar-spectroscopy: continuum and line spectra.
- Basic properties of interstellar dust.
- Shocks: blast waves, Rankine-Hugoniot conditions, cosmic rays, diffusive shock acceleration.
- Synchrotron radiation: power radiated, spectrum, spectral ageing.
- Black holes: accretion discs, active galactic nuclei, superluminal jets, Compton scattering, gravitational waves.
- Galaxy clusters: thermal bremsstrahlung radiation and the Sunyaev-Zeldovich effect.

Literature:
- Radiative Processes in Astrophysics by George B. Rybicki and Alan P. Lightman
- High Energy Astrophysics by Malcolm S. Longair

Intended Knowledge Outcomes

At the end of the module, it is expected that students will be able to:
- Reproduce the mathematical description of the radiation field and its interaction with matter.
- Explain the formation of spectral lines, ionization, and the basics of stellar spectra.
- Explain the role of approximations like local thermodynamic equilibrium
- Explain the basic principles behind shock acceleration, synchrotron radiation, Compton scattering and bremsstrahlung radiation.
- Describe astrophysical systems such as X-ray binaries, jets, black hole mergers and galaxy clusters.

Intended Skill Outcomes

- Ability to solve the radiative transfer equation, and to determine from this whether a system will exhibit emission or absorption lines.
- Ability to calculate line fluxes and ratios, and use this to measure properties such as temperature, density and column density.
- Ability to calculate ionization balance.
- Ability to derive the strong shock conditions and the basic equations of diffusive shock acceleration.
- Ability to calculate the power-law index and characteristic frequencies of synchrotron radiation.
- Ability to calculate the temperature of an accretion disc and the apparent velocity of a superluminal jet ejection.

Students will develop skills across the cognitive domain (Bloom's taxonomy, 2001 revised edition): remember, understand, apply, analyse, evaluate and create.

Teaching Rationale And Relationship

The teaching methods are appropriate to allow students to develop a wide range of skills, from understanding basic concepts and facts to higher-order thinking. Lectures are used for the delivery of theory and explanation of methods, illustrated with examples.

Assessment Rationale And Relationship

A substantial formal unseen examination is appropriate for the assessment of the material in this module. The format of the examination will enable students to reliably demonstrate their own knowledge, understanding and application of learning outcomes. The assurance of academic integrity forms a necessary part of programme accreditation.

Examination problems may require a synthesis of concepts and strategies from different sections, while they may have more than one ways for solution. The examination time allows the students to test different strategies, work out examples and gather evidence for deciding on an effective strategy, while carefully articulating their ideas and explicitly citing the theory they are using.

The coursework assignment allows the students to develop their problem-solving techniques, to practise the methods learnt in the module, and it is crucial to assess their progress and to receive feedback. This assessment has a secondary formative purpose as well as their primary summative purpose. Students will also be able to practice problem solving skills with the provided practice questions, but the summative assessment is essential for gauging progress, providing feedback and, if needed, extra support.

General Notes

N/A