Biennial report of: The Mullard Radio Astronomy Observatory, Cavendish Laboratory, University of Cambridge

For the period 1st Jan 1995 to 31st Dec 1996

This report covers all the activities of the Radioastronomy group of the University of Cambridge Department of Physics. It is loosely divided into four main sections, which deal respectively with Astronomy and Astrophysics, Instruments and Techniques, Applications of the Geometric Algebra to problems in theoretical physics , and on the work on Inferential Methods. The astronomical side of our work is mostly funded by PPARC. On the other hand, some of the work on the Spacetime Algebra and on Inferential Methods, which has grown directly out of our astronomical interests, is now funded by EPSRC.

The report is not exhaustive; a full list of references arising from the work described is given in Appendix E. Other appendices provide a list of staff and students, the facilities we have used, the institutions with which we have collaborated, and the conferences at which our work was presented.

Highlights

• The first-ever high-resolution (arcmin) image of primordial structure in the CMB, using the Cosmic Anistropy Telescope (CAT) and the Ryle Telescope.

• the remarkable detection of a CMB decrement towards a 3-arcmin separation quasar pair at , using the Ryle Telescope.

• Hubble constant determinations of and via the Sunyaev-Zel'dovich and X-ray route, from two clusters with different gas properties.

• The discovery that higher-luminosity FRII radio sources are powered by jets of greater mass flux rather than greater Lorentz factor.

• Prediction of the star-formation rate in our own Galaxy using a model of self-propagating star formation which gives excellent agreement with observation.

• Discovery of quasi-periodic radio oscillations in the extreme X-ray transient GRS 1915+105.

• Direct demonstration that some molecular outflows are driven by precessing time-dependent jets which entrain material at jet bow-shocks.

• Detection of spectral-index variations at submillimetre wavelengths in the NGC2024 cloud core, consistent with the idea that dust coagulation is occurring prior to planetisimal formation.

• The first high-resolution (20 milliarcsec) image of a star using an optical aperture synthesis array, made of Capella using COAST, followed by the first imaging observations of a resolved stellar disk (Betelgeuse).

• The direct detection of the variation in apparent diameter of a Mira variable (R Leo) as a function of pulsation phase and wavelength.

• The demonstration (in a collaboration with the University of Köln) of a tunerless, arrayable finline mixer with K noise temperature between 215 and 265GHz.

• 1 Astronomy and Astrophysics
  • 1.1 Cosmic microwave background
  • 1.2 Active galaxies and star formation
  • 1.3 Star formation
  • 1.4 Astrophysics of evolved stars
• 2 Instruments and techniques
  • 2.1 Cosmic Anisotropy Telescope
  • 2.2 Ryle Telescope
  • 2.3 CLFST
  • 2.4 COAST
  • 2.5 JOSE
  • 2.6 Submillimetre interferometry
  • 2.7 Millimetre-wave instrumentation
  • 2.8 Antennas
  • 2.9 Data Processing
• 3 Applications of Geometric Algebra
• 4 Inferential Sciences
• A Staff (at 28th February 1997)
• B Students approved for degrees
• C Use of Facilities
• D Collaborations
• E References
• F Conferences