Search Publications
Stirring in massive, young debris discs from spatially resolved Herschel images
Krivov, A. V.; Apai, D.; Ábrahám, P. +9 more
A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesim…
Searching for correlations in simultaneous X-ray and UV emission in the narrow-line Seyfert 1 galaxy 1H 0707-495
Fabian, A. C.; Gallo, L. C.; Zoghbi, A. +1 more
We examine simultaneous X-ray and UV light curves from multi-epoch 8 d XMM-Newton observations of the narrow line Seyfert 1 galaxy 1H 0707-495. The simultaneous observations reveal that both X-ray and UV emission are variable and that the amplitude of the X-ray variations is significantly greater than that of the UV variations in both epochs. Usin…
The JCMT Plane Survey: early results from the ℓ = 30° field
Martin, P. G.; Hill, T.; White, G. J. +55 more
We present early results from the JCMT (James Clerk Maxwell Telescope) Plane Survey (JPS), which has surveyed the northern inner Galactic plane between longitudes ℓ = 7° and ℓ = 63° in the 850-µm continuum with SCUBA-2 (Submm Common-User Bolometer Array 2), as part of the JCMT Legacy Survey programme. Data from the ℓ = 30° survey region, whi…
Star formation rates from young-star counts and the structure of the ISM across the NGC 346/N66 complex in the SMC
Bernard, J. -P.; Lebouteiller, V.; Madden, S. C. +21 more
The rate at which interstellar gas is converted into stars, and its dependence on environment, is one of the pillars on which our understanding of the visible Universe is build. We present a comparison of the surface density of young stars (Σ⋆) and dust surface density (Σdust) across NGC 346 (N66) in 115 independent pixels of…
Revealing the X-ray variability of AGN with principal component analysis
Fabian, A. C.; Brenneman, L.; Matt, G. +7 more
We analyse a sample of 26 active galactic nuclei (AGN) with deep XMM-Newton observations, using principal component analysis (PCA) to find model-independent spectra of the different variable components. In total, we identify at least 12 qualitatively different patterns of spectral variability, involving several different mechanisms, including five…
The 1.4-GHz radio properties of hard X-ray-selected AGN
Bird, A. J.; Ubertini, P.; Malizia, A. +7 more
We have analysed the NRAO Very Large Array Sky Survey and Sydney University Molonglo Sky Survey data at 1.4 GHz and 843 MHz for a well-defined complete sample of hard X-ray AGN observed by INTEGRAL. A large number (70/79) of sources are detected in the radio band, showing a wide range of radio morphologies, from unresolved or slightly resolved cor…
The X-ray outburst of the Galactic Centre magnetar SGR J1745-2900 during the first 1.5 year
Campana, S.; Tiengo, A.; Mereghetti, S. +17 more
In 2013 April a new magnetar, SGR 1745-2900, was discovered as it entered an outburst, at only 2.4 arcsec angular distance from the supermassive black hole at the centre of the Milky Way, Sagittarius A*. SGR 1745-2900 has a surface dipolar magnetic field of ∼2 × 1014 G, and it is the neutron star closest to a black hole ever observed. T…
On the origin of excess cool gas in quasar host haloes
Johnson, Sean D.; Chen, Hsiao-Wen; Mulchaey, John S.
Previous observations of quasar host haloes at z ≈ 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z ≈ 1 with constraints on chemically enriched, cool gas trac…
No breakdown of the radiatively driven wind theory in low-metallicity environments
Bouret, J. -C.; Martins, F.; Hillier, D. J. +3 more
We present a spectroscopic analysis of Hubble Space Telescope/Cosmic Origins Spectrograph observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with Very Large Telescope (VLT)/X-shooter by Tramper et al., who claimed that their mass-loss rates are higher than expected from …
On the nature of Hα emitters at z ∼ 2 from the HiZELS survey: physical properties, Lyα escape fraction and main sequence
Smail, I.; Cepa, J.; Ivison, R. J. +4 more
We present a detailed multiwavelength study (from rest-frame ultraviolet to far-infrared) of narrow-band selected, star-forming (SF) Hα emitters (HAEs) at z ∼ 2.23 taken from the High-Redshift(Z) Emission Line Survey (HiZELS). We find that HAEs have similar properties and colours derived from spectral energy distributions as sBzK galaxies, and pro…