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A Turbulent Model of Gamma-Ray Burst Variability
Ramesh Narayan, Pawan Kumar
A popular paradigm to explain the rapid temporal variability observed in gamma-ray burst (GRB) lightcurves is the internal shock model. We propose an alternative model in which the…
Inferring the Inclination of a Black Hole Accretion Disk from Observations of its Polarized Continuum Radiation
Li-Xin Li, Ramesh Narayan, Jeffrey E. McClintock
Spin parameters of stellar-mass black holes in X-ray binaries are currently being estimated by fitting the X-ray continuum spectra of their accretion disk emission. For this method…
A New Dynamical Model for the Black Hole Binary LMC X-1
Jerome A. Orosz, Danny Steeghs, Jeffrey E. McClintock +10
We present a dynamical model of the high mass X-ray binary LMC X-1 based on high-resolution optical spectroscopy and extensive optical and near-infrared photometry. From our new op…
A Simple Comptonization Model
James F. Steiner, Ramesh Narayan, Jeffrey E. McClintock +1
We present an empirical model of Comptonization for fitting the spectra of X-ray binaries. This model, "simpl", has been developed as a package implemented in XSPEC. With only two…
Three-Dimensional Simulations of Magnetized Thin Accretion Disks around Black Holes: Stress in the Plunging Region
Rebecca Shafee, Jonathan C. McKinney, Ramesh Narayan +3
We describe three-dimensional general relativistic magnetohydrodynamic simulations of a geometrically thin accretion disk around a non-spinning black hole. The disk has a thickness…
Properties of Gamma-Ray Burst Progenitor Stars
Pawan Kumar, Ramesh Narayan, Jarrett L. Johnson
We determine some basic properties of stars that produce spectacular gamma-ray bursts at the end of their life. We assume that accretion of the outer portion of the stellar core by…
Mass Fall-back and Accretion in the Central Engine of Gamma-Ray Bursts
Pawan Kumar, Ramesh Narayan, Jarrett L. Johnson
We calculate the rate of in-fall of stellar matter on an accretion disk during the collapse of a rapidly rotating massive star, and estimate the luminosity of the relativistic jet…
Embedded Oscillating Starless Cores
Avery E. Broderick, Ramesh Narayan, Eric Keto +1
In a previous paper we demonstrated that non-radial hydrodynamic oscillations of a thermally-supported (Bonnor-Ebert) sphere embedded in a low-density, high-temperature medium pers…
Precise Measurement of the Spin Parameter of the Stellar-Mass Black Hole M33 X-7
Jifeng Liu, Jeffery E. McClintock, Ramesh Narayan +2
In prior work, {\it Chandra} and Gemini-North observations of the eclipsing X-ray binary M33 X-7 have yielded measurements of the mass of its black hole primary and the system's or…
A simplified global solution for an advection-dominated accretion flow
Feng Yuan, Renyi Ma, Ramesh Narayan
When we model black hole accretion sources such as active galactic nuclei and black hole X-ray binaries as advection-dominated accretion flows (ADAFs), it is neccesary to use the g…