Lent Term Courses

Most of your Part II Astrophysics courses follow a strictly disciplinary approach: teaching specific physics to tackle specific astrophysical problems.  Yet, much research is inherently interdisciplinary, motivated primarily by outstanding questions about the Universe and then adopting whatever mix of methods, observational and theoretical, are required to address these questions.  In Topics the aim is to develop your familiarity with this more research-oriented, question-first, approach to astrophysics, by exploring interdisciplinary astrophysics via two different, but complementary approaches: applying specific physical concepts to diverse astrophysical phenomena; and, applying diverse physical concepts to specific research themes, focusing on the physics of supernovae and the evolutionary pathway from interstellar gas to the formation of planets.

In the first 3 lectures we present some of the tools that are required in order to get an approximate grasp on problems where all the information is not necessarily available. This is largely an exercise in sorting out the important from the unimportant and requires a good understanding of timescales and distributions. During the remainder of the first half of the course we investigate how a specific physical concept (that of tides) can be applied to understanding a wide diversity of astrophysical phenomena from quasars and supermassive black holes, to stellar clusters, asteroids and moons.  This exemplifies how mastery of specific physical concepts can open up a diverse range of astrophysical processes to investigation. 

In the second half of the course, we focus on two specific research themes: the physics of supernovae and the formation and evolution of protoplanetary discs. In the former we look at issues such as what are the processes determining the properties and evolutionary timescales for emission from supernovae, as well as considering the types of stars that end up as supernovae. In the latter, we look at the evolution of the dust and gas originating in dense cores in the interstellar medium and chart the processes that can ultimately lead to the creation of planets of the types observed in the solar system and amongst the thousands of recently discovered extrasolar planets. Throughout you will be learning how to break problems down into elements that can be tackled by simple calculations using the physics that you already know or will have learned elsewhere in Part II Astrophysics.

To further your understanding of astrophysics as a research discipline, the core lectures from the course are interspersed with `Guest Lectures’, in which a number of staff in astronomy departments across Cambridge will provide a perspective on their cutting-edge research. 

Section 1: Introduction to problem solving techniques [3]

Section 2: The physics of tides and its astronomical applications on all scales [3]

Section 3: The physics of supernovae [6]

Section 4: From molecular cloud cores to discs to the brink of planet formation [6]

Guest lectures will be interspersed among the above lectures, tbd [6]

Recommended Reading

There are no textbooks to support the course. However, for students who are interested in learning more about some of the topics covered, the following books (in addition to those supporting other Part II Astro. courses) are recommended: 

• P. Armitage, The Astrophysics of Planet Formation, Cambridge University Press, 2010. 
• Frank, J., King, A., Raine, D., Accretion Power in Astrophysics, Cambridge   University Press, 2002
• F. Mellia High Energy Astrophysics, Princeton University Press, 2009
• D. Ward-Thompson & A. Whitworth, An Introduction to Star Formation, Cambridge   University Press, 2011

1. Is Cosmology Science?: Causal structure of space-time: our past light cone. Technology horizon, particle horizon and the `size' of the Universe. Importance of symmetry principles in cosmology. Big problems in cosmology. [1] 
2. The Background Cosmology: Symmetric spaces. The Friedmann-Robertson-Walker metric. Energy Momentum Tensor for Perfect Fluid. Friedman equations and geometry of the Universe. Cosmological redshift. Newtonian cosmology. Cosmological constant. de-Sitter space and time-slicing. Horizons. Distances and age of the Universe.[6] 
3. Thermal History: The cosmic microwave background (CMB) radiation. Thermal equilibrium: bosons and fermions. Particle content at early times. Neutrinos and neutrino decoupling. Big-bang nucleosynthesis. Relic particles. Dark matter. Baryon asymmetry. Recombination. [5] 
4. Fluctuations: Newtonian perturbation theory. Fluctuations in the CMB – Silk Damping. Inflation and the origin of fluctuations. Gravitational waves and tests of inflation. What can we learn from the CMB? The LCDM model. The multiverse. Unanswered questions. [5] 
5. Observational Probes: Standard candles – Type 1a supernovae. Standard ruler – Baryon Acoustic Oscillations. Inverse distance ladder and H0. Forward distance ladder and H0. Gravitational lensing. Redshift space distortions. Is LCDM consistent with observations? [4] 
6. Non-Linear Evolution of Structure: Spherical collapse model. The mass function. Galaxy formation. [4] 

Recommended Reading

• Modern Cosmology, Dodelson D., Schmidt F., 2020, Academic Press
• Principles of Physical Cosmology, Peebles P.J.E., 1993, Princeton University Press
• General Relativity: An Introduction for Physicists, Hobson M.P., Efstathiou G.  and Lasenby A.N., 2006, Cambridge University Press