Search Publications
H0LiCOW - V. New COSMOGRAIL time delays of HE 0435-1223: H0 to 3.8 per cent precision from strong lensing in a flat ΛCDM model
Treu, T.; Auger, M. W.; Koopmans, L. V. E. +15 more
We present a new measurement of the Hubble Constant H0 and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. First, we measure the time delay of HE 0435-1223 from 13-yr light curves obtained as part of the COSMOGRAIL project. Companion papers detail…
The Hubble Space Telescope UV Legacy Survey of Galactic globular clusters - IX. The Atlas of multiple stellar populations
Salaris, M.; Anderson, J.; Milone, A. P. +17 more
We use high-precision photometry of red-giant-branch (RGB) stars in 57 Galactic globular clusters (GCs), mostly from the `Hubble Space Telescope (HST) UV Legacy Survey of Galactic GCs', to identify and characterize their multiple stellar populations. For each cluster the pseudo-two-colour diagram (or `chromosome map') is presented, built with a su…
A deep ALMA image of the Hubble Ultra Deep Field
Ivison, R. J.; Scott, D.; van Kampen, E. +36 more
We present the results of the first, deep Atacama Large Millimeter Array (ALMA) imaging covering the full ≃4.5 arcmin2 of the Hubble Ultra Deep Field (HUDF) imaged with Wide Field Camera 3/IR on HST. Using a 45-pointing mosaic, we have obtained a homogeneous 1.3-mm image reaching σ1.3 ≃ 35 µJy, at a resolution of ≃0.7 a…
Lyα and C III] emission in z = 7-9 Galaxies: accelerated reionization around luminous star-forming systems?
Charlot, Stéphane; Chevallard, Jacopo; Tang, Mengtao +9 more
We discuss new Keck/MOSFIRE spectroscopic observations of four luminous galaxies at z ≃ 7-9 selected to have intense optical line emission by Roberts-Borsani et al. Previous follow-up has revealed Lyα in two of the four galaxies. Our new MOSFIRE observations confirm that Lyα is present in the entire sample. We detect Lyα emission in the galaxy COS…
H0LiCOW - I. H0 Lenses in COSMOGRAIL's Wellspring: program overview
Treu, T.; Blandford, R. D.; Auger, M. W. +21 more
Strong gravitational lens systems with time delays between the multiple images allow measurements of time-delay distances, which are primarily sensitive to the Hubble constant that is key to probing dark energy, neutrino physics and the spatial curvature of the Universe, as well as discovering new physics. We present H0LiCOW (H0 Lenses …
The Frontier Fields lens modelling comparison project
Sharon, K.; Diego, J. M.; Zitrin, A. +20 more
Gravitational lensing by clusters of galaxies offers a powerful probe of their structure and mass distribution. Several research groups have developed techniques independently to achieve this goal. While these methods have all provided remarkably high-precision mass maps, particularly with exquisite imaging data from the Hubble Space Telescope (HS…
Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured
Sanders, D. B.; Harrison, F.; Stern, D. +10 more
Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion on to supermassive black holes (SMBHs), giving rise to active galactic nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-s…
HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water
Madhusudhan, Nikku; MacDonald, Ryan J.
Interpretations of exoplanetary transmission spectra have been undermined by apparent obscuration due to clouds/hazes. Debate rages on whether weak H2O features seen in exoplanet spectra are due to clouds or inherently depleted oxygen. Assertions of solar H2O abundances have relied on making a priori model assumptions, for ex…
Calibration of weak-lensing shear in the Kilo-Degree Survey
Hoekstra, H.; Merten, J.; Herbonnet, R. +3 more
We describe and test the pipeline used to measure the weak-lensing shear signal from the Kilo-Degree Survey (KiDS). It includes a novel method of 'self-calibration' that partially corrects for the effect of noise bias. We also discuss the 'weight bias' that may arise in optimally weighted measurements, and present a scheme to mitigate that bias. T…
H0LiCOW - IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology
Treu, Tommaso; Marshall, Philip J.; Sonnenfeld, Alessandro +13 more
Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H0. We present a blind lens model analysis of the quadruply imaged quasar lens HE 0435-1223 using deep Hubbl…