Cosmology
What is Cosmology?
The rather grand goal of cosmology is to understand the formation and evolution of our Universe. We now have a 'standard' model which is in broad agreement with our observations, but many holes remain. The hot big-bang model is supported by many separate lines of evidence and we now think the the current content of the Universe is 4% normal matter, 22% percent dark matter and 74% dark energy. While we understand the normal matter (the stuff that makes up the stars, planets, you and I), we have a severe lack of understanding when it comes to dark matter and dark energy. Dark matter is though to be made up of weakly interacting massive particles (WIMPs) that have not so far been detected in the laboratory. Instead, dark matter is inferred from the gravitional effect it has on the visible matter. We have even less clue about dark energy! This was only recently discovered and is driving the ongoing acceleration of the Universe (which was previously thought to be deccelerating). Dark energy could take a number of forms, incuding Einstein's infamous cosmological constant, changes to gravity as descibed by general relativity or assorted exotic scalar fields related to inflation in the early universe, to name but a few.
Current research areas
Fundamental General Relativity and Cosmology
The theory of General Relativity is close to 100 years old and has been the preferred theory of gravity since its formulation by Einstein. Despite this, the understanding of General Relativity is not as advanced as might be expected, with few formal solutions existing and the physical interpretation of some of the mathematical results being unclear. The Gravitational Astrophysics group conducts research into fundamental concepts in GR including the meaning and nature of expanding space and accelerated paths into black holes.
For more information contact Geraint Lewis or see the Gravitational Astrophysics Group website
Numerical Cosmology
Members of our group study the implications of various dark energy models, primarily through N-body simulations, in order to increase the theoretical understanding of dark energy physics required in order to maximise the effectiveness of future surveys and instruments.
For more information contact Geraint Lewis or see the Gravitational Astrophysics Group website
The WiggleZ Dark Energy Survey
Scott Croom is a part of the WiggleZ team which is using the Anglo-Australian Telescope to construct a huge redshift survey of ~400,000 galaxies at redshifts z~0.5-1.3. The goal of this survey is to measure the "equation of state" of dark energy at high redshift. This is done by making high-precision measurements of the clustering of galaxies which ought to reveal the baryon acoustic oscillations (BAOs or baryon wiggles), a relic feature from the primordial Big Bang. This encodes a fundamental physical scale whose size we can measure from the cosmic microwave background. Measuring this standard ruler at z=0.75 will give us the first high-precision measurement of dark energy independent of previous supernovae determinations.
For more information contact Scott Croom