MPhys Physics

Fundamentals of radio astronomy: 
The universe as observable using radio telescopes will be described. Ways to quantify measurements of radio telescope in terms of brightness, flux density and brightness temperature will be developed, as well of simple radiative transfer of radio waves through the interstellar medium and Earth’s atmosphere. This understanding will be applied to various emission mechanisms: thermal radiation, synchrotron continuum radiation, Bremsstrahlung and spectral lines.

Antenna concepts

The basics of radio antenna characteristics will be described, including parabolic antennas. Wave optics and Fourier transform principles are applied to radio antenna’s, including the understanding of differences between near and far-field and beam solid angles, and their effect on surveys to map the sky. Various limitations of aperture efficiency will be discussed.

Receiver concepts 
Noise contributions to the signals recorded by radio telescopes are quantified, and described in terms of Johnson noise, band-limited noise, the Nyquist theorem and noise temperature. This leads to the ability to work out the minimum required observing time to get a detection of a radio source. Different types of receiver systems (and their components) are described in detail, including heterodyne systems and spectral line receivers. The effect of gain instabilities, and ways to improve receiver systems to deal with this are discussed. Interferometric receiver concepts are explained to understand how radio images can be obtained by linking radio telescopes together in different ways. This includes understanding of spatial and temporal coherence, resolution; complex visibilities and aperture synthesis.

Case Studies 
Application of radio astronomy techniques to specific astrophysical targets e.g. discrete source surveys; the Cosmic Microwave Background; radio pulsars. 

1. To provide an overview of phenomena which can be studied with radio techniques including a range of non-astronomical applications.
2. To introduce the techniques of radio astronomy, from antennas to radio receivers, emphasising their strengths and limitations and the applicability of these techniques to a range of non-astronomical applications.

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

ILO 1

Relate radio-waveband observations of astrophysical objects to the mechanism that generated the emission.

ILO 2

Quantify how radio waves are affected as they travel through the interstellar medium and the Earth’s atmosphere.

ILO 3

Calculate key performance indicators of a radio telescope such as its sensitivity and angular resolution.

ILO 4

Explain the optimum choice of receiver system for a desired radio astronomical measurement.

ILO 5

Describe the operation and advantages of radio interferometers in imaging applications.

1. Fundamentals
The radio universe: “hidden” objects (pulsars, double radio sources, OH/IR stars etc) and a new light on the familiar (e.g. HII regions, supernova remnants, spiral galaxies).
Brightness, flux density and brightness temperature, emission mechanisms, thermal and synchrotron continuum radiation, spectral lines, simple radiative transfer, antenna characteristics.

2.   Antenna concepts
The antenna as an aperture; Rayleigh distance; far-field Fourier transform relations and differences for the near field; effective area, aperture efficiency; beam solid angles and antenna gain; antenna temperature; Ruze formula; Wiener-Kinchine theorem, convolution and antenna smoothing; parabolic antennas and basics of quasi-optics.

3.   Receiver concepts
Johnson noise; Nyquist theorem and noise temperature, band-limited noise, minimum detectable signal, noise accounting in receivers; heterodyne systems and sidebands; polarization sensitive receivers; gain instabilities; Dicke-switched and correlation receivers.
Spectral line receiver concept: detectability of spectral lines, filter bank, autocorrelation and Fourier transform receiver principles.
Interferometric receiver concepts; spatial and temporal coherence; adding, phase switching and multiplying types; resolution; complex visibilities; aperture synthesis and imaging of various targets.

4.   Case Studies
Application of radio astronomy techniques to specific astrophysical targets e.g. discrete source surveys; the Cosmic Microwave Background; mm-wave imaging of Earth from space; mm-wave imaging of terrestrial targets for all-weather surveillance and security.

One two-hour, live in-person lectures per week where the core material with examples will be delivered. The recordings of these lectures will be available online. The lectures are accompanied by detailed online lecture notes. This is augmented by a weekly online quiz with feedback, and a set of weekly problems with feedback. A Piazza discussion forum is also provided 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