Lecturer: tba

Weighting: 15 CATS

We will discuss the compact objects - white dwarfs, neutron stars and black holes (BH) - that can form when burnt out stars collapse under their own gravity. The extreme conditions in their neighbourhood mean that they affect strongly all nearby objects as well as the surrounding structure of space-time. For example, they can lead to very high luminosity phenomena, such as synchrotron radiation and jets of ionised particles that we can observe from Earth.

These compact objects accrete material from surrounding gases and nearby stars. In the case of BHs this can lead to the supermassive BHs thought to be at the centre of most galaxies. In the most extreme events (mergers of these objects), the gravitational waves (GW) that are emitted can sometimes be detected on earth (the first GW detection was reported in 2015 almost exactly 100 years after their prediction by Einstein).

Aims:
To cover the physics of black holes, white dwarfs and neutron stars highlighting the role of observation. To give an overview of the possible formation and growth channels of these objects and to discuss their interactions.

Objectives:
By the end of the module, students should:

• be aware of the structure of our own Galaxy and how it fits into the ‘zoo’ of galaxies distributed through the Universe
• understand the physical principles behind the observations used to study galaxies
• be aware of some of the outstanding, and only partially understood, problems in the study of galaxies including the nature of galaxy cores and the roles of dark matter and dust.

Syllabus:

The module describes both observational and theoretical classifications for different galaxy types and for our own Milky Way:

1. Observational instrumentation, telescope design, detectors
2. Accretion onto compact objects as a source of energy, Eddington limit: a maximum accretion rate, structure and the emission of accretion disks, accretion onto magnetic stars, Alven radius
3. High energy astrophysics: jets in astrophysical objects, radiation from free electrons, synchrotron radiation, cyclotron radiation, thermal Bremsstrahlung from hot accretion plasmas
4. Nuclear physics: stable and unstable nuclear shell burning in accreting white dwarfs and neutron stars
5. Formation pathways for black holes. Supernovae, gamma-ray bursts. Exploding white dwarfs, merging neutron stars. Mergers and associated gravitational wave emission

Commitment: 30 lectures

Assessment: 2 hour examination

Recommended texts: H Bradt, Astronomy Methods: A Physical Approach to Astronomical Observations, Cambridge University Press
J Frank, AR King and DJ Raine, Accretion Power in Astrophysics, CUP
C Hellier Cataclysmic Variables: How and why they vary, Springer