MPhys Physics with Theoretical Physics / Course details

This unit will cover the fundamentals of how radio emission is generated (thermal emission, Bremsstrahlung, synchrotron radiation and line emission) and covers a broad range of astrophysical objects that can be observed with radio telescopes. Antenna designs and different types of receiver systems (basic radiometers, heterodyne systems, correlation receivers) will be discussed, covering topics ranging from wave optics and beam forming to the electronics required to build a receiver. Many of the modern radio observatories are built as interferometers. In this unit the fundamentals of radio interferometry are covered, including the formation of radio images of the sky by combining the signals from different antennas, thereby pointing out the advantages and disadvantages of different approaches

1. To provide an overview of astronomical phenomena which can be studied with radio techniques and illustrate these with case studies. These include pulsars, HII regions, supernova remnants, active galactic nuclei, and the Cosmic Microwave Background.

2. To introduce the techniques of radio astronomy, from antennas to radio receivers to interferometers, emphasising their strengths and limitations. 

On the successful completion of the course, students will be able to:  

 -  Assess the effects of propagation of radio waves through interstellar space and the Earth’s atmosphere, and infer the relevant radiation mechanisms from observations. 

 -  Appraise key performance indicators of a radio telescope such as sensitivity and angular resolution, and explain the way receiver systems and their components function. 

 -  Discuss the operation of radio interferometers, and formulate the impact of array design on imaging performance

1.    Brief overview of radio astronomy (1 lecture): Overview of the module and a historical context.

2.    Fundamentals of radio emission (2 lectures): Surface brightness, flux density and brightness temperature and simple radiative transfer. Thermal emission.

3.    Radio emission mechanisms (3 lectures): Link the fundamentals of radio emission to radio continuum emission mechanisms: synchrotron radiation and Bremsstrahlung. Fundamentals of radio spectral lines.

4.    Radiative transfer (2 lectures): Propagation of radio waves through a medium, and the effects of observing through Earth’s atmosphere.

5.    Antenna concepts (3 lectures): Parabolic antennas; the antenna as an aperture; Rayleigh distance; far-field Fourier transform relations and differences for the near field; effective area, aperture efficiency, and their relation to telescope design; beam solid angles and antenna gain; antenna temperature; Wiener-Kinchine theorem, convolution and antenna smoothing.

6.    Receiver concepts (4 lectures): Johnson noise; Nyquist theorem and noise temperature; band-limited noise, signal detection and minimum detectable signal, noise accounting in receivers; basic radiometer.

7.    Receiver systems (6 lectures): heterodyne systems and sidebands; gain instabilities; Dicke-switched and correlation receivers; spectral line and polarimeter receiver concepts; filter bank, autocorrelation and Fourier transform receiver principles.

8.    Fundamentals of interferometry (5 lectures): Interferometric receiver concepts; spatial and temporal coherence; adding and multiplying types; resolution; complex visibilities; aperture synthesis.

9.    Imaging with interferometers (4 lectures): Field of view limitations: bandwidth and integration time smearing, w-term. Deconvolution and the CLEAN algorithm. Correction of telescope-based gains: closure quantities, self-calibration.

10.    State of the art of interferometry (2 lectures): Examples of modern advances in experiments, techniques, and scientific applications.

11.    Revision (1 lecture) 

Three one hour, live in-person lectures per week where the core material with examples will be delivered. The recordings of these lectures (podcasts) will be available. The lectures are accompanied by extensive notes in the form of powerpoint slides, a typeset document containing the more involved mathematical derivations, and a brief summary of required knowledge of, for example, Fourier Transforms. A quiz and example sheet will be made available every week on Canvas, and detailed feedback will be made available explaining the answers. A discussion forum will be provided on Canvas where students can ask questions with answers provided by other students and the unit lead. 

"An Introduction to Radio Astronomy" Burke, Graham-Smith, Wilkinson

"Essential Radio Astronomy" Condon, Ransom

"Tools of Radio Astronomy" Wilson, Rohlfs, Huttemeister 

Full list: see https://www.readinglists.manchester.ac.uk/leganto/public/44MAN_INST/lists/333420863850001631?auth=CAS