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The slimming effect of advection on black-hole accretion flows
(EDP Sciences, 2016)
We study energy flows in geometrically thick accretion discs, both optically thick and thin, using general relativistic, three-dimensional simulations of black hole accretion flows. We find that for non-rotating black holes ...
Discovery of an Outflow from Radio Observations of the Tidal Disruption event ASASSN-14li
(American Astronomical Society, 2016)
We report the discovery of transient radio emission from the nearby optically-discovered TDE ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation ...
Fast Variability and Millimeter/IR Flares in GRMHD Models of Sgr A* From Strong-Field Gravitational Lensing
(IOP Publishing, 2015)
We explore the variability properties of long, high cadence GRMHD simulations across the electromagnetic spectrum using an efficient, GPU-based radiative transfer algorithm. We focus on both disk- and jet-dominated simulations ...
A Parallax Distance to the Microquasar Grs 1915+105 and a Revised Estimate of Its Black Hole Mass
(IOP Publishing, 2014)
Using the Very Long Baseline Array, we have measured a trigonometric parallax for the microquasar GRS 1915+105, which contains a black hole and a K-giant companion. This yields a direct distance estimate of 8.6 +2.0 −1.6 ...
Testing Slim-Disk Models on the Thermal Spectra of LMC X-3
(EDP Sciences, 2011)
Slim-disk models describe advective accretion flows at high luminosities, while reducing to the standard thin disk form in the low luminosity limit. We have developed a new spectral model, slimbb, within the framework of ...
The Trigonometric Parallax of Cygnus X-1
(IOP Publishing, 2011)
We report a direct and accurate measurement of the distance to the X-ray binary Cygnus X-1, which contains the first black hole to be discovered. The distance of 1.86+0.12 – 0.11 kpc was obtained from a trigonometric ...
The Cool Accretion Disk in ESO 243-49 HLX-1: Further Evidence of an Intermediate-Mass Black Hole
(IOP Publishing, 2011)
With an inferred bolometric luminosity exceeding \(10^{42}\;erg\;s^{–1}\), HLX-1 in ESO 243-49 is the most luminous of ultraluminous X-ray sources and provides one of the strongest cases for the existence of intermediate-mass ...
Bondi Flow from a Slowly Rotating Hot Atmosphere
(Oxford University Press (OUP), 2011)
A supermassive black hole in the nucleus of an elliptical galaxy at the centre of a cool-core group or cluster of galaxies is immersed in hot gas. Bondi accretion should occur at a rate determined by the properties of the ...
The Extreme Spin of the Black Hole in Cygnus X-1
(IOP Publishing, 2011)
The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination ...
Simulations of ultrarelativistic magnetodynamic jets from gamma-ray burst engines
(Oxford University Press (OUP), 2008)
Long-duration gamma-ray bursts (GRBs) require an engine capable of driving a jet of plasma to ultrarelativistic bulk Lorentz factors of up to several hundred and into narrow opening angles of a few degrees. We use global ...