Search Publications
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…
The Python Sky Model: software for simulating the Galactic microwave sky
Dunkley, J.; Alonso, D.; Thorne, B. +1 more
We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of cosmic microwave background experiments. This python code builds on existing efforts to simulate the sky by providing an easy-to-use interface and is based on publicly available data from the WMAP (Wilki…
Prospects for detection of detached double white dwarf binaries with Gaia, LSST and LISA
Toonen, Silvia; Brown, Anthony G. A.; Nelemans, Gijs +3 more
Double white dwarf (DWD) binaries are expected to be very common in the Milky Way, but their intrinsic faintness challenges the detection of these systems. Currently, only a few tens of detached DWDs are know. Such systems offer the best chance of extracting the physical properties that would allow us to address a wealth of outstanding questions r…
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…
Lensing is low: cosmology, galaxy formation or new physics?
Viel, Matteo; Leauthaud, Alexie; Heymans, Catherine +19 more
We present high signal-to-noise galaxy-galaxy lensing measurements of the Baryon Oscillation Spectroscopic Survey constant mass (CMASS) sample using 250 deg2 of weak-lensing data from Canada-France-Hawaii Telescope Lensing Survey and Canada-France-Hawaii Telescope Stripe 82 Survey. We compare this signal with predictions from mock catal…
KiDS-450: the tomographic weak lensing power spectrum and constraints on cosmological parameters
Heymans, C.; Choi, A.; Hoekstra, H. +13 more
We present measurements of the weak gravitational lensing shear power spectrum based on 450 ° ^2 of imaging data from the Kilo Degree Survey. We employ a quadratic estimator in two and three redshift bins and extract band powers of redshift autocorrelation and cross-correlation spectra in the multipole range 76 ≤ ℓ ≤ 1310. The cosmological interpr…
KiDS-450: testing extensions to the standard cosmological model
Hoekstra, Henk; Heymans, Catherine; Kuijken, Konrad +16 more
We test extensions to the standard cosmological model with weak gravitational lensing tomography using 450 deg2 of imaging data from the Kilo Degree Survey (KiDS). In these extended cosmologies, which include massive neutrinos, non-zero curvature, evolving dark energy, modified gravity and running of the scalar spectral index, we also e…
The GALAH survey: observational overview and Gaia DR1 companion
Freeman, K. C.; Marshall, J. P.; Da Costa, G. S. +31 more
The Galactic Archaeology with HERMES (GALAH) survey is a massive observational project to trace the Milky Way's history of star formation, chemical enrichment, stellar migration and minor mergers. Using high-resolution (R ≃ 28 000) spectra, taken with the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) instrument at the Anglo-Au…