Killedar, Madhura, Lewis, Geraint F.
The evolution of the expansion rate of the Universe results in a drift in the redshift of distant sources over time. A measurement of this drift would provide us with a direct probe of expansion...
Lane, Richard R., Kiss, László L., Lewis, Geraint F., Ibata, Rodrigo A., Siebert, Arnaud, Bedding, Timothy R., ...
Globular clusters are an important test bed for Newtonian gravity in the weak-acceleration regime, which is vital to our understanding of the nature of the gravitational interaction. Recent claims...
The Adventures of the Rocketeer: Accelerated Motion Under the Influence of Expanding Space (2009)
Kwan, Juliana, Lewis, Geraint F., James, J. Berian
It is well known that interstellar travel is bounded by the finite speed of light, but on very large scales any rocketeer would also need to consider the influence of cosmological expansion on their...
The remnants of galaxy formation from a panoramic survey of the region around M31 (2009)
McConnachie, Alan W., Irwin, Michael J., Ibata, Rodrigo A., Dubinski, John, Widrow, Lawrence M., Martin, Nicolas F., ...
In hierarchical cosmological models, galaxies grow in mass through the continual accretion of smaller ones. The tidal disruption of these systems is expected to result in loosely bound stars...
Martin, Nicolas F., McConnachie, Alan W., Irwin, Mike, Widrow, Lawrence M., Ferguson, Annette M. N., Ibata, Rodrigo A., ...
We present the discovery of two new dwarf galaxies, Andromeda XXI and Andromeda XXII, located in the surroundings of the Andromeda and Triangulum galaxies (M31 and M33). These discoveries stem from...
Testing Newtonian Gravity with AAOmega: Mass-to-Light Profiles of Four Globular Clusters (2009)
Lane, Richard R., Kiss, László L., Lewis, Geraint F., Ibata, Rodrigo A., Siebert, Arnaud, Bedding, Timothy R., ...
Testing Newtonian gravity in the weak-acceleration regime is vital to our understanding of the nature of the gravitational interaction. It has recently been claimed that the velocity dispersion...
Gravitational Microlensing: A parallel, large-data implementation (2009)
Garsden, Hugh, Lewis, Geraint F.
Gravitational lensing allows us to probe the structure of matter on a broad range of astronomical scales, and as light from a distant source traverses an intervening galaxy, compact matter such as...
Fractal Bubble Cosmology: A concordant cosmological model? (2009)
Kwan, Juliana, Francis, Matthew J., Lewis, Geraint F.
The Fractal Bubble model has been proposed as a viable cosmology that does not require dark energy to account for cosmic acceleration, but rather attributes its observational signature to the...
Riechers, Dominik A., Walter, Fabian, Carilli, Chirstopher L., Lewis, Geraint F.
We have mapped the molecular gas content in the host galaxy of the strongly lensed high-redshift quasar APM 08279+5255 (z = 3.911) with the Very Large Array at 0\farcs3 resolution. The CO(J = 1➝0)...
Riechers, Dominik A., Walter, Fabian, Brewer, Brendon J., Carilli, Christopher L., Lewis, Geraint F., Bertoldi, Frank, ...
We present high-resolution (0.3") Very Large Array imaging of the molecular gas in the host galaxy of the high-redshift quasar PSS J2322+1944 (z = 4.12). These observations confirm that the molecular...
Topology of non-linear structure in the 2dF Galaxy Redshift Survey (2008)
James, J. Berian, Colless, Matthew, Lewis, Geraint F., Peacock, John A.
We study the evolution of non-linear structure as a function of scale in samples from the 2dF Galaxy Redshift Survey, constituting over 221 000 galaxies at a median redshift of z=0.11. The two...
Halo Mass Functions in Early Dark Energy Cosmologies (2008)
Francis, Matthew J., Lewis, Geraint F., Linder, Eric V.
We examine the linear density contrast at collapse time, $\delta_c$ for large-scale structure in dynamical dark energy cosmologies, including models with early dark energy. Contrary to previous...
Riechers, Dominik A., Walter, Fabian, Carilli, Christopher L., Lewis, Geraint F.
We have mapped the molecular gas content in the host galaxy of the strongly lensed high redshift quasar APM 08279+5255 (z=3.911) with the Very Large Array at 0.3" resolution. The CO(J=1-0) emission...
Can Early Dark Energy be Detected in Non-Linear Structure? (2008)
Francis, Matthew J., Lewis, Geraint F., Linder, Eric V.
We present the first study of early dark energy cosmologies using N-body simulations to investigate the formation of non-linear structure. In contrast to expectations from semi-analytic approaches,...
Riechers, Dominik A., Walter, Fabian, Brewer, Brendon J., Carilli, Christopher L., Lewis, Geraint F., Bertoldi, Frank, ...
We present high-resolution (0.3") Very Large Array imaging of the molecular gas in the host galaxy of the high-redshift quasar PSS J2322+1944 (z=4.12). These observations confirm that the molecular...
A trio of new local group galaxies with extreme properties (2008)
McConnachie, Alan W., Huxor, Avon, Martin, Nicolas F., Irwin, Mike J., Chapman, Scott C., Fahlman, Gregory, ...
We report on the discovery of three new dwarf galaxies in the Local Group. These galaxies are found in new CFHT/MegaPrime g,i imaging of the southwestern quadrant of M31, extending our extant survey...
Expanding Space: the Root of all Evil? (2007)
Francis, Matthew J., Barnes, Luke A., James, J. Berian, Lewis, Geraint F.
While it remains the staple of virtually all cosmological teaching, the concept of expanding space in explaining the increasing separation of galaxies has recently come under fire as a dangerous idea...
Probing the Nature of the G1 Clump Stellar Overdensity in the Outskirts of M31 (2006)
Faria, Daniel, Johnson, Rachel A., Ferguson, Annette M. N., Irwin, Mike J., Ibata, Rodrigo A., Johnston, Kathryn V., ...
We present deep HST/ACS observations of the G1 clump, a distinct stellar overdensity lying at ~30 kpc along the south-western major axis of M31 close to the G1 globular cluster (Ferguson et al....
The Einstein Ring 0047-2808 Revisited: A Bayesian Inversion (2006)
Brewer, Brendon J., Lewis, Geraint F.
In a previous paper, we outlined a new Bayesian method for inferring the properties of extended gravitational lenses, given data in the form of resolved images. This method holds the most promise for...
The stellar halo and outer disk of M33 (2006)
McConnachie, Alan W., Chapman, Scott C., Ibata, Rodrigo A., Ferguson, Annette M. N., Irwin, Mike J., Lewis, Geraint F., ...
We present first results from a Keck/DEIMOS spectroscopic survey of red giant branch (RGB) stars in M33. The radial velocity distributions of the stars in our fields are well described by three...
Internal alignment of the halos of disk galaxies in cosmological hydrodynamic simulations (2005)
Bailin, Jeremy, Kawata, Daisuke, Gibson, Brad K., Steinmetz, Matthias, Navarro, Julio F., Brook, Chris B., ...
Seven cosmological hydrodynamic simulations of disk galaxy formation are analyzed to determine the alignment of the disk within the dark matter halo and the internal structure of the halo. We find...
Anisotropy in the Distribution of Satellite Galaxy Orbits (2004)
Knebe, Alexander, Gill, Stuart P., Gibson, Brad K., Lewis, Geraint F., Ibata, Rodrigo A., Dopita, Michael A.
Nearby clusters such as Virgo and Coma possess galaxy distributions that tend to be aligned with the principal axis of the cluster itself. This has also been confirmed by a recent statistical...
Anisotropy in the Distribution of Satellite Galaxy Orbits (2004)
Knebe, Alexander, Gill, Stuart P., Gibson, Brad K., Lewis, Geraint F., Ibata, Rodrigo A., Dopita, Michael A.
Nearby clusters such as Virgo and Coma possess galaxy distributions that tend to be aligned with the principal axis of the cluster itself. This has also been confirmed by a recent statistical...
Physical implications of the x-ray properties of galaxy groups and clusters (2002)
Babul, Arif, Balogh, Michael L., Lewis, Geraint F., Poole, Gregory B.
Within the standard framework of structure formation, where clusters and groups of galaxies are built up from the merging of smaller systems, the physical properties of the intracluster medium, such...
AAT/WFI observations of the extragalactic HI cloud HIPASS JI712-64 (2002)
Gibson, Bradley K., Ibata, Rodrigo A., Irwin, Michael J., Lewis, Geraint F.
AAT/WFI optical images of a candidate extragalactic HI cloud, HIPASS J1712–64, are presented. The g and r band CCD mosaic camera frames were processed using a new data pipeline recently installed...
Physical implications of the x-ray properties of galaxy groups and clusters (2002)
Babul, Arif, Balogh, Michael L., Lewis, Geraint F., Poole, Gregory B.
Within the standard framework of structure formation, where clusters and groups of galaxies are built up from the merging of smaller systems, the physical properties of the intracluster medium, such...
Ibata, Rodrigo, Lewis, Geraint F., Irwin, Michael, Totten, Edward, Quinn, Thomas
An all high-latitude sky survey for cool carbon giant stars in the Galactic halo has revealed 75 such stars, of which the majority are new detections. Of these, more than half are clustered on a...
Detecting dark matter in high-velocity clouds (2000)
Lewis, Geraint F., Bland-Hawthorn, Joss, Gibson, Brad K., Putman, Mary E.
Abstract not available.