Search Publications
Properties of galaxies reproduced by a hydrodynamic simulation
Genel, S.; Xu, D.; Nelson, D. +7 more
Previous simulations of the growth of cosmic structures have broadly reproduced the `cosmic web' of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of numerical inaccuracies and incomplete physical models. Moreover, they were unable to track the small-scale evolution of gas a…
Clouds in the atmosphere of the super-Earth exoplanet GJ1214b
Deming, Drake; Stevenson, Kevin B.; Désert, Jean-Michel +7 more
Recent surveys have revealed that planets intermediate in size between Earth and Neptune (`super-Earths') are among the most common planets in the Galaxy. Atmospheric studies are the next step towards developing a comprehensive understanding of this new class of object. Much effort has been focused on using transmission spectroscopy to characteriz…
The diversity of quasars unified by accretion and orientation
Shen, Yue; Ho, Luis C.
Quasars are rapidly accreting supermassive black holes at the centres of massive galaxies. They display a broad range of properties across all wavelengths, reflecting the diversity in the physical conditions of the regions close to the central engine. These properties, however, are not random, but form well-defined trends. The dominant trend is kn…
A featureless transmission spectrum for the Neptune-mass exoplanet GJ436b
Deming, Drake; Knutson, Heather A.; Benneke, Björn +1 more
GJ436b is a warm--approximately 800 kelvin--exoplanet that periodically eclipses its low-mass (half the mass of the Sun) host star, and is one of the few Neptune-mass planets that is amenable to detailed characterization. Previous observations have indicated that its atmosphere has a ratio of methane to carbon monoxide that is 105 times…
Localized sources of water vapour on the dwarf planet (1)Ceres
Marston, Anthony; Müller, Thomas; Lee, Seungwon +10 more
The `snowline' conventionally divides Solar System objects into dry bodies, ranging out to the main asteroid belt, and icy bodies beyond the belt. Models suggest that some of the icy bodies may have migrated into the asteroid belt. Recent observations indicate the presence of water ice on the surface of some asteroids, with sublimation a potential…
A supermassive black hole in an ultra-compact dwarf galaxy
Neumayer, Nadine; Strader, Jay; Brodie, Jean +11 more
Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 108 solar masses, but half-light radii of just 3-50 parsecs. Dynamical mass estimates show that many such dwarfs are more massive than expected from their luminosity. It remains unclear whether these high dynamical …
The Laniakea supercluster of galaxies
Tully, R. Brent; Pomarède, Daniel; Hoffman, Yehuda +1 more
Galaxies congregate in clusters and along filaments, and are missing from large regions referred to as voids. These structures are seen in maps derived from spectroscopic surveys that reveal networks of structure that are interconnected with no clear boundaries. Extended regions with a high concentration of galaxies are called `superclusters', alt…
A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
Motch, C.; Soria, R.; Pakull, M. W. +2 more
Most ultraluminous X-ray sources have a typical set of properties not seen in Galactic stellar-mass black holes. They have luminosities of more than 3 × 1039 ergs per second, unusually soft X-ray components (with a typical temperature of less than about 0.3 kiloelectronvolts) and a characteristic downturn in their spectra above about 5 …
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet
Deming, Drake; Madhusudhan, Nikku; Knutson, Heather +6 more
Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to su…
A 400-solar-mass black hole in the galaxy M82
Mushotzky, Richard F.; Pasham, Dheeraj R.; Strohmayer, Tod E.
M82 X-1, the brightest X-ray source in the galaxy M82, has been thought to be an intermediate-mass black hole (100 to 10,000 solar masses) because of its extremely high luminosity and variability characteristics, although some models suggest that its mass may be only about 20 solar masses. The previous mass estimates were based on scaling relation…