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Hargrave P.C.,University of Cardiff | Savini G.,University College London | Trappe N.,National University of Ireland, Maynooth | Challinor A.,Institute of Astronomy and Kavli Institute for Cosmology Cambridge | And 8 more authors.
2013 7th European Conference on Antennas and Propagation, EuCAP 2013 | Year: 2013

We present an ongoing programme of work to investigate the use of large dielectric lenses with coating layers for future satellite-based cosmic microwave background (CMB) polarimetry missions. The primary purpose of this study is to validate modelling and manufacturing techniques. We present details of the study, and preliminary results of material and lens testing. © 2013 EurAAP. Source


Brook C.B.,University of Central Lancashire | Governato F.,University of Washington | Roskar R.,University of Washington | Roskar R.,University of Zurich | And 9 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

Using high resolution, fully cosmological smoothed particle hydrodynamical simulations of dwarf galaxies in a Lambda cold dark matter Universe, we show how high redshift gas outflows can modify the baryon angular momentum distribution and allow pure disc galaxies to form. We outline how galactic outflows preferentially remove low angular momentum material due a combination of (a) star formation peaking at high redshift in shallow dark matter potentials, an epoch when accreted gas has relatively low angular momentum, (b) the existence of an extended reservoir of high angular momentum gas in the outer disc to provide material for prolonged SF at later times and (c) the tendency for outflows to follow the path of least resistance which is perpendicular to the disc. We also show that outflows are enhanced during mergers, thus expelling much of the gas which has lost its angular momentum during these events, and preventing the formation of 'classical', merger driven bulges in low-mass systems. Stars formed prior to such mergers form a diffuse, extended stellar halo component similar to those detected in nearby dwarfs. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS. Source


Hanson D.,Institute of Astronomy and Kavli Institute for Cosmology Cambridge | Challinor A.,Institute of Astronomy and Kavli Institute for Cosmology Cambridge | Challinor A.,University of Cambridge | Lewis A.,Institute of Astronomy and Kavli Institute for Cosmology Cambridge | Lewis A.,University of Sussex
General Relativity and Gravitation | Year: 2010

The cosmic microwave background (CMB) represents a unique source for the study of gravitational lensing. It is extended across the entire sky, partially polarized, located at the extreme distance of z = 1,100, and is thought to have the simple, underlying statistics of a Gaussian random field. Here we review the weak lensing of the CMB, highlighting the aspects which differentiate it from the weak lensing of other sources, such as galaxies. We discuss the statistics of the lensing deflection field which remaps the CMB, and the corresponding effect on the power spectra. We then focus on methods for reconstructing the lensing deflections, describing efficient quadratic maximum-likelihood estimators and delensing. We end by reviewing recent detections and observational prospects. © 2010 Springer Science+Business Media, LLC. Source

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