Search Publications
The AIMSS Project II: dynamical-to-stellar mass ratios across the star cluster-galaxy divide
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +5 more
The previously clear division between small galaxies and massive star clusters is now occupied by objects called ultra-compact dwarfs (UCDs) and compact ellipticals (cEs). Here we combine a sample of UCDs and cEs with velocity dispersions from the AIMSS project with literature data to explore their dynamical-to-stellar mass ratios. We confirm that…
The low or retrograde spin of the first extragalactic microquasar: implications for Blandford-Znajek powering of jets
Middleton, Matthew J.; Miller-Jones, James C. A.; Fender, Rob P.
Transitions to high mass accretion rates in black hole X-ray binaries are associated with the ejection of powerful, relativistically moving jets. The mechanism that powers such events is thought to be linked to tapping of the angular momentum (spin) of the black hole, the rate of accretion through the disc or some combination of the two. We can at…
Low-redshift quasars in the Sloan Digital Sky Survey Stripe 82. The host galaxies
Falomo, R.; Uslenghi, M.; Kotilainen, J. K. +2 more
We present a photometrical and morphological study of the properties of low-redshift (z < 0.5) quasars based on a large and homogeneous data set of objects derived from the Sloan Digital Sky Survey Data Release 7. This study over number by a factor of ∼5 any other previous study of quasi-stellar object (QSO) host galaxies at low redshift undert…
Swift J1357.2-0933: the faintest black hole?
Degenaar, N.; Wijnands, R.; Fender, R. P. +3 more
Swift J1357.2-0933 is a confirmed very faint black hole X-ray transient and has a short estimated orbital period of 2.8 h. We observed Swift J1357.2-0933 for ∼50 ks with XMM-Newton in 2013 July during its quiescent state. The source is clearly detected at a 0.5-10 keV unabsorbed flux of ∼3 × 10-15 erg cm-2 s-1. If …
Properties of starless and prestellar cores in Taurus revealed by Herschel: SPIRE/PACS imaging
Hill, T.; André, Ph.; Könyves, V. +18 more
The density and temperature structures of dense cores in the L1495 cloud of the Taurus star-forming region are investigated using Herschel Spectral and Photometric Imaging Receiver and Photodetector Array Camera and Spectrometer images in the 70, 160, 250, 350 and 500 µm continuum bands. A sample consisting of 20 cores, selected using spectr…
A 7 deg2 survey for galaxy-scale gravitational lenses with the HST imaging archive
Faure, C.; Meylan, G.; Courbin, F. +2 more
We present the results of a visual search for galaxy-scale gravitational lenses in ∼7 deg2 of Hubble Space Telescope (HST) images. The data set comprises the whole imaging data ever taken with the Advanced Camera for Surveys (ACS) in the filter F814W (I-band) up to 2011 August 31, i.e. 6.03 deg2 excluding the field of the Cos…
A variable P v broad absorption line and quasar outflow energetics
Hamann, F.; Capellupo, D. M.; Barlow, T. A.
Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that might exist in all quasars and could play a major role in feedback to galaxy evolution. The viability of BAL outflows as a feedback mechanism depends on their kinetic energies, as derived from the outflow velocities, column densities, and distances from the centra…
Sérsic galaxy models in weak lensing shape measurement: model bias, noise bias and their interaction
Rowe, Barnaby; Kacprzak, Tomasz; Zuntz, Joe +4 more
Cosmic shear is a powerful probe of cosmological parameters, but its potential can be fully utilized only if galaxy shapes are measured with great accuracy. Two major effects have been identified which are likely to account for most of the bias seen for maximum likelihood methods in recent shear measurement challenges. Model bias occurs when the t…
An X-ray view of the very faint black hole X-ray transient Swift J1357.2-0933 during its 2011 outburst
Altamirano, D.; Degenaar, N.; Wijnands, R. +3 more
We report on the X-ray spectral (using XMM-Newton data) and timing behaviour [using XMM-Newton and Rossi X-ray Timing Explorer (RXTE) data] of the very faint X-ray transient and black hole system Swift J1357.2-0933 during its 2011 outburst. The XMM-Newton X-ray spectrum of this source can be adequately fitted with a soft thermal component with a t…
PAH formation in O-rich planetary nebulae
Zijlstra, A. A.; Jones, D.; Lagadec, E. +2 more
Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense …