Browsing by Author "Cress, Catherine"

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    Galaxy evolution, cosmology and HPC : clustering studies applied to astronomy
    (2016) Tshililo, Israel R; Cress, Catherine; Winberg, Simon
    Tools to measure clustering are essential for analysis of Astronomical datasets and can potentially be used in other fields for data mining. The Two-point Correlation Function (TPCF), in particular, is used to characterize the distribution of matter and objects such as galaxies in the Universe. However, it's computational time will be restrictively slow given the significant increase in the size of datasets expected from surveys in the future. Thus, new computational techniques are necessary in order to measure clustering efficiently. The objective of this research was to investigate methods to accelerate the computation of the TPCF and to use the TPCF to probe an interesting scientific question dealing with the masses of galaxy clusters measured using data from the Planck satellite. An investigation was conducted to explore different techniques and architectures that can be used to accelerate the computation of the TPCF. The code CUTE, was selected in particular to test shared-memory systems using OpenMP and GPU acceleration using CUDA. Modification were then made to the code, to improve the nearest neighbour boxing technique. The results show that the modified code offers a significant improved performance. Additionally, a particularly effective implementation was used to measure the clustering of galaxy clusters detected by the Planck satellite: our results indicated that the clusters were more massive than had been inferred in previous work, providing an explanation for apparent inconsistencies in the Planck data.
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    HI Lightcones for LADUMA using Gadget-3 : performance profiling and application of an HPC code
    (2014) Cawood, Matthew Roy; Inggs, Michael; Cress, Catherine; Macleod, David
    This project concerns the investigation, performance profiling and optimisation of the high performance cosmological code, GADGET-3. This code was used to develop a synthetic field-of-view, or lightcone, for the MeerKAT telescope to replicate what it will observe when it conducts the LADUMA ultra-deep HI survey. This lightcone will assist in the planning process of the survey. The deliverables for this project are summarised as follows: * Provide an up-to-date performance evaluation and optimisation report for the cosmological simulation code GADGET-3. * Use GADGET-3 to produce an sufficiently high resolution simulation of a region of the Universe. • Develop a Python code to produce a lightcone which represents the MeerKAT telescope's field-of-view, by post-processing simulation output snapshots. * Extract relevant metadata from the simulation snapshots to provide additional insight into the simulated observation. * Produce an efficiently written and well documented software package to enable other researchers to produce synthetic lightcones.