Search Publications
Does black hole growth depend fundamentally on host-galaxy compactness?
Alexander, D. M.; Brandt, W. N.; Xue, Y. Q. +5 more
Possible connections between central black hole (BH) growth and host-galaxy compactness have been found observationally, which may provide insight into BH-galaxy coevolution: compact galaxies might have large amounts of gas in their centres due to their high mass-to-size ratios, and simulations predict that high central gas density can boost BH ac…
Mass variance from archival X-ray properties of Dark Energy Survey Year-1 galaxy clusters
Smith, M.; Annis, J.; Brooks, D. +77 more
Using archival X-ray observations and a lognormal population model, we estimate constraints on the intrinsic scatter in halo mass at fixed optical richness for a galaxy cluster sample identified in Dark Energy Survey Year-One (DES-Y1) data with the redMaPPer algorithm. We examine the scaling behaviour of X-ray temperatures, TX, with opt…
Gaia-DR2 distance to the W3 Complex in the Perseus Arm
Damineli, Augusto; Navarete, Felipe; Galli, Phillip A. B.
The Perseus Arm is the closest Galactic spiral arm from the Sun, offering an excellent opportunity to study in detail its stellar population. However, its distance has been controversial with discrepancies by a factor of two. Kinematic distances are in the range 3.9-4.2 kpc as compared to 1.9-2.3 kpc from spectrophotometric and trigonometric paral…
Prevalence of neutral gas in centres of merging galaxies-II: nuclear H I and multiwavelength properties
Srianand, R.; Gupta, N.; Dutta, R.
Using a sample of 38 radio-loud galaxy mergers at z ≤ 0.2, we confirm the high detection rate (∼84 per cent) of H I 21-cm absorption in mergers, which is significantly higher (∼4 times) than in non-mergers. The distributions of the H I column density [N({H I})] and velocity shift of the absorption with respect to the systemic redshift of the galax…
The distances to star clusters hosting Red Supergiants: χ Per, NGC 7419, and Westerlund 1
Beasor, Emma R.; Davies, Ben
Galactic, young massive star clusters are approximately coeval aggregates of stars, close enough to resolve the individual stars, massive enough to have produced large numbers of massive stars, and young enough for these stars to be in a pre-supernova state. As such these objects represent powerful natural laboratories in which to study the evolut…
Stellar disc streams as probes of the Galactic potential and satellite impacts
Laporte, Chervin F. P.; Johnston, Kathryn V.; Tzanidakis, Anastasios
Stars aligned in thin stream-like features (feathers), with widths of δ ∼ 1-10° and lengths as large as Δl ∼ 180°, have been observed towards the Anticentre of our Galaxy and their properties mapped in abundances and phase-space. We study their origin by analysing similar features arising in an N-body simulation of a Galactic disc interacting with…
Robust identification of active galactic nuclei through HST optical variability in GOODS-S: comparison with the X-ray and mid-IR-selected samples★
Hatzidimitriou, D.; Georgantopoulos, I.; Gavras, P. +9 more
Identifying active galactic nuclei (AGNs) through their X-ray emission is efficient, but necessarily biased against X-ray-faint objects. We aim to characterize this bias by comparing X-ray-selected AGNs to the ones identified through optical variability and mid-infrared (mid-IR) colours. We present a catalogue of AGNs selected through optical vari…
The tilt of the local velocity ellipsoid as seen by Gaia
Evans, N. W.; Belokurov, V.; Schönrich, R. +1 more
The Gaia Radial Velocity Spectrometer (RVS) provides a sample of 7224 631 stars with full six-dimensional phase space information. Bayesian distances of these stars are available from the catalogue of Schönrich, McMillan & Eyer. We exploit this to map out the behaviour of the velocity ellipsoid within 5 kpc of the Sun. We find that the tilt of…
The host galaxies of FeLoBAL quasars at z ∼ 0.9 are not dominated by recent major mergers
Villforth, C.; Hamann, F.; Hamilton, T. +4 more
Theoretical models have suggested an evolutionary model for quasars, in which most of luminous quasars are triggered by major mergers. It is also postulated that reddening as well as powerful outflows indicate an early phase of activity, close to the merger event. We test this model on a sample of quasars with powerful low-ionization outflows seen…
The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
Klessen, Ralf S.; Federrath, Christoph; Schneider, Nicola +1 more
Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, M, allows us to predict the rate of star formation. However, determining Mach numbers in observations is challenging because it requires accurate measurements of the velocity d…