Search Publications
The SAURON project - IX. A kinematic classification for early-type galaxies
Krajnović, Davor; Emsellem, Eric; van de Ven, Glenn +10 more
Two-dimensional stellar kinematics of 48 representative elliptical (E) and lenticular (S0) galaxies obtained with the SAURON integral-field spectrograph reveal that early-type galaxies appear in two broad flavours, depending on whether they exhibit clear large-scale rotation or not. We define a new parameter , which involves luminosity-weighted av…
An XMM-Newton survey of broad iron lines in Seyfert galaxies
Nandra, K.; Reeves, J. N.; George, I. M. +1 more
We present an analysis of the X-ray spectra of a sample of 37 observations of 26 Seyfert galaxies observed by XMM-Newton in order to characterize their iron Kα emission. All objects show evidence for iron line emission in the 6-7 keV band. A narrow `core' at 6.4 keV is seen almost universally in the spectra, and we model this using a neutral Compt…
The SAURON project - X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/σ, ɛ) diagram with integral-field stellar kinematics
Krajnović, Davor; Emsellem, Eric; van de Ven, Glenn +11 more
We analyse the orbital distribution of elliptical (E) and lenticular (S0) galaxies using SAURON integral-field stellar kinematics within about one effective (half-light) radius. We construct the anisotropy diagram, which relates the ratio of the ordered and random motion in a galaxy (V/σ) to its observed ellipticity (ɛ), for the 48 E/S0 galaxies f…
Strong size evolution of the most massive galaxies since z ∼ 2
Cooper, M. C.; Ellis, Richard S.; Trujillo, Ignacio +3 more
Using the combined capabilities of the large near-infrared Palomar/DEEP-2 survey, and the superb resolution of the Advanced Camera for Surveys HST camera, we explore the size evolution of 831 very massive galaxies (M⋆≥ 1011h-270 M⊙) since z~ 2. We split our sample according to their light conc…
Piecing together the X-ray background: bolometric corrections for active galactic nuclei
Fabian, A. C.; Vasudevan, R. V.
The X-ray background can be used to constrain the accretion history of supermassive black holes (SMBHs) in active galactic nuclei (AGN), with the SMBH mass density related to the energy density due to accretion. A knowledge of the hard X-ray bolometric correction, κ2-10keV, is a vital input into these studies, as it allows us to constra…
The Shear Testing Programme 2: Factors affecting high-precision weak-lensing analyses
Refregier, Alexandre; Ellis, Richard; Schrabback, Tim +28 more
The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak-lensing measurement, in preparation for the next generation of wide-field surveys. We review 16 current and emerging shear-measurement methods in a common language, and assess their performance by running them (blindly) on simulated images…
A kinematical approach to dark energy studies
Allen, Steven W.; Rapetti, David; Blandford, Roger D. +1 more
We present and employ a new kinematical approach to cosmological `dark energy' studies. We construct models in terms of the dimensionless second and third derivatives of the scalefactor a(t) with respect to cosmic time t, namely the present-day value of the deceleration parameter q0 and the cosmic jerk parameter, j(t). An elegant featur…
Cepheid parallaxes and the Hubble constant
van Leeuwen, Floor; Whitelock, Patricia A.; Feast, Michael W. +1 more
Revised Hipparcos parallaxes for classical Cepheids are analysed together with 10 Hubble Space Telescope (HST)-based parallaxes. In a reddening-free V, I relation we find that the coefficient of logP is the same within the uncertainties in our Galaxy as in the Large Magellanic Cloud (LMC), contrary to some previous suggestions. Cepheids in the inn…
Cosmological constraints from the 100-deg2 weak-lensing survey
Hoekstra, Henk; Heymans, Catherine; Mellier, Yannick +7 more
We present a cosmic shear analysis of the 100-deg2 weak-lensing survey, combining data from the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS surveys. Spanning ~100 deg2, with a median source redshift z~ 0.78, this combined survey allows us to place tight joint constraints on the matter density parameter Ωm, and the …
A double main-sequence turn-off in the rich star cluster NGC 1846 in the Large Magellanic Cloud
Mackey, A. D.; Broby Nielsen, P.
We report on Hubble Space Telescope/ACS photometry of the rich intermediate-age star cluster NGC 1846 in the Large Magellanic Cloud, which clearly reveals the presence of a double main-sequence turn-off in this object. Despite this, the main-sequence, subgiant branch and red giant branch are all narrow and well defined, and the red clump is compac…