Related papers: On Arcs and Omega
We review theoretical approaches to the study of galaxy formation, with emphasis on the role of hydrodynamic simulations in modeling the high redshift galaxy population. We present new predictions for the abundance of star-forming galaxies…
We calculate the expected number of strongly lensed radio sources in a sample of 6500 sources observed with the Very Large Array as part of the Cosmic Lens All Sky Survey (CLASS) during the first two sessions of its observations. A…
Many distant objects can only be detected, or become more scientifically valuable, if they have been highly magnified by strong gravitational lensing. We use EAGLE and BAHAMAS, two recent cosmological hydrodynamical simulations, to predict…
The motions of galaxies can be used to constrain the cosmological density parameter Omega and the clustering amplitude of matter on large scales. The mean relative velocity of galaxy pairs, estimated from the Mark III survey, indicates that…
The statistics of gravitationally lensed arcs was recognised earlier as a potentially powerful cosmological probe. However, while fully numerical models find orders of magnitude difference between the arc probabilities in different…
Galaxy clusters as gravitational lenses play a unique role in astrophysics and cosmology: they permit mapping the dark matter distribution on a range of scales; they reveal the properties of high and intermediate redshift background…
Galaxy clusters identified with optical imaging tend to suffer from projection effects, which impact richness (the number of member galaxies in a cluster) and lensing coherently. Physically unassociated galaxies can be mistaken as cluster…
The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z >~ 7, when galaxies reionized the Universe. Standard models predict that a high…
With today's millimeter and submillimeter instruments observers use gravitational lensing mostly as a tool to boost the sensitivity when observing distant objects. This is evident through the dominance of gravitationally lensed objects…
We report the discovery of a cluster of galaxies via its weak gravitational lensing effect on background galaxies, the first spectroscopically confirmed cluster to be discovered through its gravitational effects rather than by its…
Selected results on estimating cosmological parameters from simulated weak lensing data with noise are presented. Numerical simulations of ray tracing through N-body simulations have been used to generate shear and convergence maps due to…
We present simulations of the formation and evolution of clusters in spiral arms. The simulations follow two different spiral arm regions, and the total gas mass is varied to produce a range of different mass clusters. We find that…
Strong gravitational lenses come in many forms, but are typically divided into two populations: galaxies, and groups and clusters of galaxies. The largest objects in the Universe (i.e. galaxy clusters) are highly irregular and composed of…
Despite consistent progress in numerical simulations, the observable properties of galaxy clusters are difficult to predict ab initio. It is therefore important to compare both theoretical and observational results to a direct measure of…
The lensing effect of curved space, which can cause the angular diameter of a fixed reference length seen on the sky to reach a minimum and then increase with redshift, depends sensitively on the value of the cosmological constant,…
We present limits on the cosmological constant from the statistics of gravitational lenses using newly completed quasar surveys, new lens data, and a range of lens models. The formal limit is $\lambda_0 < 0.66$ at 95\% confidence in flat…
Globular clusters will be present at high redshifts, near the very beginning of the galaxy formation process. Stellar evolution ensures that they will be much more luminous than today. We show that the redshift distribution at nano-Jansky…
Clusters of galaxies at z>1 are expected to be increasingly active sites of star formation. To test this, an 850um survey was undertaken of eight high-redshift clusters at z=1.6-2.0 using SCUBA-2 on the James Clerk Maxwell Telescope.…
Numerical simulations of a Milky Way-size galaxy demonstrate that globular clusters with the properties similar to observed can form naturally at z > 3 in the concordance Lambda-CDM cosmology. The clusters in our model form in the strongly…
The galaxy population in rich local galaxy clusters shows a ratio of one quarter elliptical galaxies, two quarters S0 galaxies, and one quarter spiral galaxies. Observations of clusters at redshift 0.5 show a perspicuously different ratio,…