Search Publications
The Canadian Cluster Comparison Project: detailed study of systematics and updated weak lensing masses
Muzzin, Adam; Hoekstra, Henk; Babul, Arif +4 more
Masses of clusters of galaxies from weak gravitational lensing analyses of ever larger samples are increasingly used as the reference to which baryonic scaling relations are compared. In this paper we revisit the analysis of a sample of 50 clusters studied as part of the Canadian Cluster Comparison Project. We examine the key sources of systematic…
The evolution of the X-ray luminosity functions of unabsorbed and absorbed AGNs out to z∼ 5
Georgakakis, A.; Nandra, K.; Aird, J. +3 more
We present new measurements of the evolution of the X-ray luminosity functions (XLFs) of unabsorbed and absorbed active galactic nuclei (AGNs) out to z ∼ 5. We construct samples containing 2957 sources detected at hard (2-7 keV) X-ray energies and 4351 sources detected at soft (0.5-2 keV) energies from a compilation of Chandra surveys supplemented…
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - V. Constraints on formation scenarios
Dalessandro, E.; Salaris, M.; Anderson, J. +16 more
We build on the evidence provided by our Legacy Survey of Galactic globular clusters (GC) to submit to a crucial test four scenarios currently entertained for the formation of multiple stellar generations in GCs. The observational constraints on multiple generations to be fulfilled are manifold, including GC specificity, ubiquity, variety, predomi…
The first ultraviolet quasar-stacked spectrum at z ≃ 2.4 from WFC3
Vignali, C.; Lusso, E.; Prochaska, J. X. +4 more
The ionizing continuum from active galactic nuclei is fundamental for interpreting their broad emission lines and understanding their impact on the surrounding gas. Furthermore, it provides hints on how matter accretes on to supermassive black holes. Using Hubble Space Telescope's Wide Field Camera 3, we have constructed the first stacked ultravio…
The formation of massive, compact galaxies at z = 2 in the Illustris simulation
van Dokkum, Pieter; Kriek, Mariska; Wellons, Sarah +13 more
Massive, quiescent galaxies at high redshift have been found to be considerably more compact than galaxies of similar mass in the local universe. How these compact galaxies formed has yet to be determined, though several progenitor populations have been proposed. Here we investigate the formation processes and quantify the assembly histories of su…
HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
Aigrain, S.; Pont, F.; Fortney, J. J. +15 more
We present Hubble Space Telescope optical and near-IR transmission spectra of the transiting hot-Jupiter WASP-31b. The spectrum covers 0.3-1.7 µm at a resolution R ∼ 70, which we combine with Spitzer photometry to cover the full-optical to IR. The spectrum is dominated by a cloud deck with a flat transmission spectrum which is apparent at wa…
Probing the role of the galactic environment in the formation of stellar clusters, using M83 as a test bench
Bastian, N.; Adamo, A.; Silva-Villa, E. +2 more
We present a study of the M83 cluster population, covering the disc of the galaxy between radii of 0.45 and 4.5 kpc. We aim to probe the properties of the cluster population as a function of distance from the galactic centre. We observe a net decline in cluster formation efficiency (Γ, i.e. amount of star formation happening in bound clusters) fro…
New redshift z ≃ 9 galaxies in the Hubble Frontier Fields: implications for early evolution of the UV luminosity density
McLure, R. J.; Dunlop, J. S.; McLeod, D. J. +3 more
We present the results of a new search for galaxies at redshift z ≃ 9 in the first two Hubble Frontier Fields with completed HST WFC3/IR and ACS imaging. To ensure robust photometric redshift solutions, and to minimize incompleteness, we confine our search to objects with H160 < 28.6 (AB mag), consider only image regions with an rms …
The behaviour of dark matter associated with four bright cluster galaxies in the 10 kpc core of Abell 3827
Richard, Johan; Hilton, Matt; Massey, Richard +20 more
Galaxy cluster Abell 3827 hosts the stellar remnants of four almost equally bright elliptical galaxies within a core of radius 10 kpc. Such corrugation of the stellar distribution is very rare, and suggests recent formation by several simultaneous mergers. We map the distribution of associated dark matter, using new Hubble Space Telescope imaging …
X-shooter reveals powerful outflows in z ∼ 1.5 X-ray selected obscured quasi-stellar objects
Lutz, D.; Maiolino, R.; Salvato, M. +20 more
We present X-shooter at Very Large Telescope observations of a sample of 10 luminous, X-ray obscured quasi-stellar objects (QSOs) at z ∼ 1.5 from the XMM-COSMOS survey, expected to be caught in the transitioning phase from starburst to active galactic nucleus (AGN)-dominated systems. The main selection criterion is X-ray detection at bright fluxes…