Survey Cosmology and Astrophysics

This rolling grant is to support cosmologists and astrophysicists at the Institute of Cosmology and Gravitation (ICG) at the University of Portsmouth. The ICG was formed in 2002 through a strategic investment from the university, and now hosts up to 50 researchers making it one of the largest extragalactic groups in the UK. Cosmology and astrophysics are experiencing a golden age of discovery driven by new advances in technology and theory. However, we still face two fundamental challenges before a more complete model of the Universe can be achieved: i) What are the properties of the 'dark matter' and 'dark energy' that make up 96% of the Universe, and ii) how do galaxies - the 'building blocks' of the Universe - form and evolve? This grant will address both these fundamental problems through the use of new, massive surveys of the sky. For example, we will use a new 520-megapixel camera on the Blanco 4-meter telescope in Chile to digitally image the southern sky. This survey - known as the Dark Energy Survey (DES) - will detect 300 million galaxies thus allowing us to measure the clustering of galaxies to high precision and detect the weak gravitational lensing of distant galaxies due to the foreground dark matter. DES will also discover thousands of distant supernovae (exploding stars) which will determine the expansion of the Universe over 70% of its lifetime. We are the only UK astronomy group involved in the new Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey (BOSS) which will measure the redshift (and thus distance) to over 1.5 million galaxies over half the age of the Universe. BOSS started in 2009 and we will use these data to study the evolution of massive galaxies, especially when compared to the latest theoretical models of galaxies produced exclusively at the ICG, understand the effect of host galaxies on supernova explosions and determine the geometry of the Universe to high precision using the Baryon Acoustic Oscillations. In addition to new optical surveys, we plan to harness the power of the next generation of radio telescopes that are just being built. The first of these is LOFAR, which has base stations spread across Europe forming an effective radio telescope over 600 kilometres in size. We will use LOFAR, in conjunction with new data from the SDSS, to study the effects of supermassive black holes on the evolution of elliptical galaxies. The energetic outflows from these black holes has been proposed as a way of slowing down the growth of such galaxies, making them 'red and dead' today. Also, the LOFAR data can be used to understand dark energy through the 'Integrated Sachs-Wolfe' effect, which is particularly sensitive to the rate of growth of structures in the Universe and thus the strength of gravity on cosmological scales. Therefore, LOFAR will be a powerful tool for testing Einstein's Theory of General Relativity which is fundamental to cosmology. Taken together, we expect to measure the density of dark energy over 70% the age of the Universe. This will tell us if it is just a constant, as first proposed by Einstein, or something more exotic like Quintessence, 'phantom energy' or extra dimensions! This data will also shed light on the properties of dark matter, which we can 'see' via gravity but does not shine like normal matter. We will also obtain a fuller understanding of the characteristics of massive galaxies throughout cosmic time. This will tell us whether the cold dark matter theory provides an adequate description of the formation and evolution of galaxies. In addition to research, the ICG staff are committed to public outreach and have been engaged in a number of visible activities in the media and local community. For example, our staff have visited many local schools to discuss their careers, their research (e.g. Galaxy Zoo), and express the fun of doing research.