Carlo Contaldi

Research Summary

[ Cosmology, Early Universe and General Relativity ]

Antony Lewis works on theoretical predictions for cosmological observables, particularly the Cosmic Microwave Background (CMB), and methods for comparing theoretical models with observation. He has developed and actively maintains and extends widely used numerical codes for computing CMB anisotropy power spectra and Monte-Carlo parameter estimation. He is also interested in different models of the early universe.

Research Projects:
(September 2002 - August 2003)

Analysis of WMAP data

Antony Lewis, with collaborators Sarah Bridle, Jochen Weller and George Efstathiou (IoA, Cambridge) performed various analyses of the new WMAP CMB anisotropy observations. In particular they examined the odd features on large scales which might appear unexpected in standard cosmologies, and performed a nearly assumption-free Monte-Carlo reconstruction of the amplitude of the primordial perturbations as a function of scale.

Joint analysis of WMAP and weak lensing data

A collaboration between Carlo Contaldi, Henk Hoekstra and Antony Lewis produced the first parameter estimates from a fully consistent joint analysis of CMB and the RCS weak lensing data. The results showed how these combinations already give constraints as good if not surpassing those from conventional combinations such as CMB with galaxy clustering data. As an extension of this line of research, Contaldi, Hoekstra and Lewis are now including the final release VIRMOS data into their pipeline in work that will be submitted shortly.

Constraints on curvaton models of inflation

Antony Lewis and Chris Gordon (DAMTP) analysed observational constrains for various 'curvaton' models of inflation, extending publicly available CMB codes to take account of correlations between the various possible kinds of primordial inhomegeneities.

Extraction of B-mode signal from CMB polarization measurements

Antony Lewis generalized previous work on the extraction of "B-mode" CMB polarization from realistically shaped observed sections of the CMB sky. This nearly exact method should allow for robust analysis and possible detection of primordial gravitational waves from future observations. Primordial gravitational waves are a powerful observational probe of different models for the early universe.

Dark energy models and the large scale CMB anisotropy

Antony Lewis and Jochen Weller (IoA, Cambridge) studied the effect of different models of dark energy on the large scale CMB anisotropy, and gave generalized constraints on various parameterizations using a combination of observed data.

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