GLIMPSE · Understanding the dark universe through 3D weak lensing reconstructions
FP7 — People (Marie Curie Actions)
- Duration
- 2015-03-01 → 2017-02-28
- EU contribution
- €221,606
- Participants
- 1
- Scheme
- MC-IEF
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Results in brief
GLIMPSE: Understanding the dark universe through 3D weak lensing reconstructions
The GLIMPSE project focused on the problem of mapping the dark matter distribution in three dimensions using measurements of weak gravitational lensing – a very complex, ill-posed problem with numerous sources of noise and signal contamination. The project built on earlier multidisciplinary work carried out by the researcher to apply state of the art ideas and techniques from the domain of signal processing to weak lensing, culminating in the development of the GLIMPSE algorithm, which showed excellent results on simulated data. The focus of this project, therefore, was to further develop and test the algorithm to enable robust treatment of the complex systematic error and noise artefacts arising in real data, and to fully understand the capabilities and limitations of the algorithm. Further work was undertaken to prepare for cosmological exploitation of the algorithm by more fully developing the theoretical framework relevant to GLIMPSE outputs, developing statistical techniques to combine constraints obtained from 3D maps with other cosmological probes, and optimising the software for application to survey data. During this reporting period, many of the project objectives were met. The GLIMPSE selection function was studied and constrained in a publication in 2015. The GLIMPSE algorithm was successfully applied to real datasets including the STAGES dataset, with results in preparation for publication. The GLIMPSE algorithm was modified to account for the complex phometric redshift errors often seen in real surveys, and optimised to run in a fraction of the time using a GPU cluster. The algorithm was further improved to include constraints from measurements of higher order lensing distortions – flexion – to provide higher resolution, more accurate reconstructions. This work was published in 2016, and as of 30 June 2016, work was ongoing to apply this method to data from the Dark Energy Survey. A study was undertaken to link weak lensing peak counts and second-order statistics to cosmological probes, helping to link GLIMPSE outputs and cosmological parameters, which was published in 2016.
Data: CORDIS, © European Union
Project objective
Weak gravitational lensing has emerged as a powerful tool to probe the distribution and nature of the dark components of our Universe, and thus to better constrain our cosmological model. For this reason, several large projects such as the Dark Energy Survey and Euclid have been commissioned to study this effect. Arising from the deflection of light due to the gravitational potential of structures in the Universe, it manifests as a small, correlated elliptical distortion -- a shear -- in galaxy images. Lensing is sensitive only to the presence of matter, and not to the nature of that matter (luminous, dark, baryonic, etc.), and thus provides an ideal and unbiased probe of the structure of the cosmic web.This proposal will address the problem of mapping the dark matter distribution in three dimensions using measurements of weak gravitational lensing. This is a very complex, ill-posed problem with numerous sources of noise and signal contamination. A focus of my postdoctoral work has been in developing a multidisciplinary approach to this problem, marking a dramatic shift from earlier methods. My new algorithm -- GLIMPSE -- demonstrates an impressive improvement in the fidelity of the maps generated, thereby for the first time opening up allowing 3D mapping techniques to directly constrain the cosmological model. With this in mind, the specific aims of this proposal are to further develop the GLIMPSE algorithm to ready the software for application to survey data, and to more fully develop the applicable theory and statistical tools to allow the outputs of GLIMPSE to be used to directly constrain our cosmological model.This development will establish GLIMPSE at the forefront of the field, and will significantly further the goals of large targeted weak lensing surveys. This is essential to a better understanding of the nature and behaviour of the dark components of the Universe.
Original text from CORDIS.
Participants
- UNIVERSITY COLLEGE LONDON · LONDONCoordinatorUnknown Region
Links
Data: CORDIS, © European Union