Experimental radio cosmology at Oxford

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics


Our understanding of the universe has been transformed over the past 15 years as a result of the detection of the fluctuations in the Cosmic Microwave Background (CMB). These fluctuations result from tiny variations in the density of the primordial cosmic fluid when the universe was a tiny fraction of a second old. These were blown up to astronomical size by an extremely rapid expansion of the universe which lasted a minute fraction of a second; a phenomenon that astronomers call 'inflation'. A large number of instruments have been built to characterize the spatial distribution of these anisotropies by measuring their magnitude as a function of angular scale (their `power spectrum'). These measurements are very important because they tell us a lot about the evolution of the universe and because the anisotropies contain the code the led to the present structure in the universe. Members of the Experimental Cosmology group at Oxford have taken a leading role in cosmology instruments such as CAT, VSA and CBI. These instruments, and others, most notably the NASA space telescope WMAP, have revealed an incredible amount of accurate information, such as that the universe has a flat geometry, its age is 13.7 billion years and that 94% of the substance in the universe is not matter as we know it, but is a combination of a new form of matter called 'dark matter', and an even more mysterious form of dark energy. Is this then the end of the story then? On the contrary, the knowledge we have gained in the last 15 years induces us to seek answers to even more fundamental questions in physics and astronomy. Dark matter is a puzzle since we cannot detect it directly, but we can at least observe its gravitational impact clearly. Dark energy however is a lot more bizarre since it causes the expansion of the universe to accelerate rather than to slow down. Is this really true or is there an alternative explanation that reconciles all our observations? Can we confirm categorically that inflation really occurred and if so at what energy scale? These are the challenges of the next generation of cosmology instruments and this STFC grant will allow Oxford to make major contributions to these exciting developments. Our work will feed into the next cosmology developments in several ways. We take part in new national and international cosmology projects that are aiming to be 10 times more sensitive than any instrument ever built. These instruments will be able to detect extremely weak signals such as the CMB polarization that hold as much information as the CMB anisotropies, thereby allowing us to build a complete picture of the evolution of the universe. Our team includes astronomers who are experts in instrument design and construction and also in observation and data analysis. We also build our own small-scale instrument to investigate specific effects that feed into the general picture, and finally we develop the basic research in technology and astrophysics that supports the above mentioned activities. The support that we have requested in this application falls directly into these categories. We requested support for post-doctoral research scientists to analyse the astronomical data that will stream from instruments that we are working hard to build. We are also asking for effort to help us develop the state of the art technology that is required for building these instruments and finally we are asking for the hardware that will allow us develop and test this technology in our laboratories. It is an exciting programme that links theory, astronomical observation and experimental physics using the tremendous potential of bright young scientist to help us understand the world around us.


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Buckle J (2009) HARP/ACSIS: a submillimetre spectral imaging system on the James Clerk Maxwell Telescope in Monthly Notices of the Royal Astronomical Society

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Tan B (2014) Ultra-Wide Intermediate Bandwidth for High-Frequency SIS Mixers in IEEE Transactions on Terahertz Science and Technology

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Tan B (2011) A High Performance 700 GHz Feed Horn in Journal of Infrared, Millimeter, and Terahertz Waves

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Tan B (2012) A 650 GHz Unilateral Finline SIS Mixer Fed by a Multiple Flare-Angle Smooth-Walled Horn in IEEE Transactions on Terahertz Science and Technology

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Tan B (2013) Preliminary Measurement Results of a 650 GHz Planar Circuit Balanced SIS Mixer in IEEE Transactions on Terahertz Science and Technology

Description We developed a new interferometer for SZ observations based on SIS mixers. We also developed novel designs of SIS mixers
Exploitation Route Continue funding the same are, namely development of future technology for astronomy.
Sectors Education,Electronics

Description RadioNet 3. The AETHER JRA
Amount € 80,000 (EUR)
Funding ID 283393 
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start 01/2012 
End 02/2016
Description RadioNet: Advanced Radio Astronomy in Europe
Amount € 1,800,000 (EUR)
Funding ID 730562 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2017 
End 12/2020
Title Multiple flare-angled feed horn arrays 
Description We have developed a new type of feed horn that has the performance of a corrugated horn but requires no corrugations. Using this technology, large format feed arrays can be fabricated cheaply and rapidly, in particular at millimetre and THz wavelengths. Radiation hard detectors 
Type Of Technology Detection Devices 
Year Produced 2009 
Impact The feed arrays are light-weight so ideal for satellite communication systems, cheap radar transmission and receiving.