Search Publications
The interstellar oxygen crisis, or where have all the oxygen atoms gone?
Wang, Shu; Li, Aigen; Jiang, B. W.
The interstellar medium (ISM) seems to have a significant surplus of oxygen which was dubbed as the `O crisis': independent of the adopted interstellar reference abundance, the total number of O atoms depleted from the gas phase far exceeds that tied up in solids by as much as ∼160 ppm of O/H. Recently, it has been hypothesized that the missing O …
Long-term monitoring of the archetype Seyfert galaxy MCG-6-30-15: X-ray, optical and near-IR variability of the corona, disc and torus
Uttley, P.; Arévalo, P.; Lira, P. +2 more
We present long-term monitoring of MCG-6-30-15 in X-rays, optical and near-IR wavelengths, collected over 5 yr of monitoring. We determine the power spectrum density of all the observed bands and show that after taking into account the host contamination similar power is observed in the optical and near-IR bands. There is evidence for a correlatio…
Star formation scales and efficiency in Galactic spiral arms
Moore, T. J. T.; Elia, D.; Plume, R. +4 more
We positionally match a sample of infrared-selected young stellar objects, identified by combining the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, Wide-field Infrared Survey Explorer and Herschel Space Observatory Herschel infrared Galactic Plane Survey, to the dense clumps identified in the millimetre continuum by the Boloca…
A free-form lensing grid solution for A1689 with new multiple images
Coe, D.; Izzo, L.; Broadhurst, T. +6 more
We examine Abell 1689 non-parametrically, combining strongly lensed Hubble Space Telescope images and weak distortions from wider field Subaru imaging. Our model incorporates member galaxies to improve the lens solution. By adding luminosity-scaled member galaxy deflections to our smooth grid, we can derive meaningful solutions with sufficient acc…
The inferred evolution of the cold gas properties of CANDELS galaxies at 0.5 < z < 3.0
Ferguson, H. C.; Koekemoer, A. M.; Faber, S. M. +13 more
We derive the total cold gas, atomic hydrogen, and molecular gas masses of approximately 24 000 galaxies covering four decades in stellar mass at redshifts 0.5 < z < 3.0, taken from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey survey. Our inferences are based on the inversion of a molecular hydrogen based star formation…
Stellar multiplicity and debris discs: an unbiased sample
Duchêne, Gaspard; Greaves, Jane; Matthews, Brenda +4 more
Circumstellar dust discs have been observed around many nearby stars. However, many stars are part of binary or multiple stellar systems. A natural question arises regarding the presence and properties of such discs in systems with more than one star. To address this, we consider a sample of 449 systems (spectral types A-M) observed with the Hersc…
Whatever happened to the progenitors of supernovae 2008cn, 2009kr and 2009md?
Fraser, Morgan; Ergon, Mattias; Mattila, Seppo +2 more
We present new late-time, high-resolution observations of the sites of supernovae (SNe) 2008cn, 2009kr and 2009md, acquired with the Hubble Space Telescope. In all instances, significant flux from the SNe is still recovered at late times. We show that the previous identification of the progenitor of SN 2008cn was actually a blend of two sources, w…
On the Fe K absorption - accretion state connection in the Galactic Centre neutron star X-ray binary AX J1745.6-2901
Nandra, K.; Degenaar, N.; Bianchi, S. +17 more
AX J1745.6-2901 is a high-inclination (eclipsing) neutron star low-mass X-ray binary (LMXB) located less than ∼1.5 arcmin from Sgr A⋆. Ongoing monitoring campaigns have targeted Sgr A⋆ frequently and these observations also cover AX J1745.6-2901. We present here an X-ray analysis of AX J1745.6-2901 using a large data set of 3…
Does the obscured AGN fraction really depend on luminosity?
Krivonos, R.; Sazonov, S.; Churazov, E.
We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstra…
The spatially-resolved star formation history of the M31 outer disc
Lewis, Geraint F.; McConnachie, Alan W.; Ibata, Rodrigo A. +4 more
We present deep Hubble Space Telescope Advanced Camera for Surveys observations of the stellar populations in two fields lying at 20 and 23 kpc from the centre of M31 along the south-west semimajor axis. These data enable the construction of colour-magnitude diagrams reaching the oldest main-sequence turn-offs (∼13 Gyr) which, when combined with a…