Search Publications
X-rays across the galaxy population - III. The incidence of AGN as a function of star formation rate
Georgakakis, A.; Aird, J.; Coil, A. L.
We map the co-eval growth of galaxies and their central supermassive black holes in detail by measuring the incidence of active galactic nuclei (AGNs) in galaxies as a function of star formation rate (SFR) and redshift (to z ∼ 4). We combine large galaxy samples with deep Chandra X-ray imaging to measure the probability distribution of specific bl…
The local high-velocity tail and the Galactic escape speed
Grand, Robert J. J.; Fattahi, Azadeh; Marinacci, Federico +4 more
We model the fastest moving (v_tot > 300 km s^{-1}) local (D ≲ 3 kpc) halo stars using cosmological simulations and six-dimensional Gaia data. Our approach is to use our knowledge of the assembly history and phase-space distribution of halo stars to constrain the form of the high-velocity tail of the stellar halo. Using simple analytical models…
Driving massive molecular gas flows in central cluster galaxies with AGN feedback
Fabian, A. C.; Combes, F.; Salomé, P. +7 more
We present an analysis of new and archival ALMA observations of molecular gas in 12 central cluster galaxies. We examine emerging trends in molecular filament morphology and gas velocities to understand their origins. Molecular gas masses in these systems span 10^9 - 10^{11} M_{⊙}, far more than most gas-rich galaxies. ALMA images reveal a distrib…
An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: high-resolution dust continuum morphologies and the link between sub-millimetre galaxies and spheroid formation
Thomson, A. P.; Ivison, R. J.; Scott, D. +15 more
We present an analysis of the morphology and profiles of the dust continuum emission in 153 bright sub-millimetre galaxies (SMGs) detected with ALMA at signal-to-noise ratios of >8 in high-resolution 0.18 arcsec (∼1 kpc) 870 µm maps. We measure sizes, shapes, and light profiles for the rest-frame far-infrared emission from these luminous …
Black hole masses of tidal disruption event host galaxies II
Jonker, Peter G.; Stone, Nicholas C.; Auchettl, Katie +8 more
We present new medium resolution, optical long-slit spectra of a sample of six ultraviolet (UV)/optical and 17 X-ray-selected tidal disruption event candidate host galaxies. We measure emission line ratios from the optical spectra, finding that the large majority of hosts are quiescent galaxies, while those displaying emission lines are generally …
The gravitational force field of the Galaxy measured from the kinematics of RR Lyrae in Gaia
Gerhard, Ortwin; Wegg, Christopher; Bieth, Marie
From a sample of 15651 RR Lyrae with accurate proper motions in Gaia DR2, we measure the azimuthally averaged kinematics of the inner stellar halo between 1.5 and 20 kpc from the Galactic centre. We find that their kinematics are strongly radially anisotropic, and their velocity ellipsoid nearly spherically aligned over this volume. Only in the in…
The halo's ancient metal-rich progenitor revealed with BHB stars
Belokurov, Vasily; Evans, N. Wyn; Koposov, Sergey E. +2 more
Using the data from the Sloan Digital Sky Survey and the Gaia satellite, we assemble a pure sample of ∼3000 blue horizontal branch (BHB) stars with 7D information, including positions, velocities, and metallicities. We demonstrate that, as traced with BHBs, the Milky Way's stellar halo is largely unmixed and cannot be well represented with a conve…
Sunyaev-Zel'dovich effect and X-ray scaling relations from weak lensing mass calibration of 32 South Pole Telescope selected galaxy clusters
Bayliss, M. B.; Schrabback, T.; von der Linden, A. +28 more
Uncertainty in mass-observable scaling relations is currently the limiting factor for galaxy-cluster-based cosmology. Weak gravitational lensing can provide direct mass calibration and reduce the mass uncertainty. We present new ground-based weak lensing observations of 19 South Pole Telescope (SPT) selected clusters at redshifts 0.29 ≤ z ≤ 0.61 a…
The magnetic early B-type stars - III. A main-sequence magnetic, rotational, and magnetospheric biography
Wade, G. A.; Neiner, C.; Shultz, M. E. +10 more
Magnetic confinement of stellar winds leads to the formation of magnetospheres, which can be sculpted into centrifugal magnetospheres (CMs) by rotational support of the corotating plasma. The conditions required for the CMs of magnetic early B-type stars to yield detectable emission in H α - the principal diagnostic of these structures - are poorl…
A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
Ingram, Adam; García, Javier A.; Mastroserio, Guglielmo +3 more
We present the publicly available model RELTRANS that calculates the light-crossing delays and energy shifts experienced by X-ray photons originally emitted close to the black hole when they reflect from the accretion disc and are scattered into our line of sight, accounting for all general relativistic effects. Our model is fast and flexible enou…