Browsing FAS Scholarly Articles by Keyword "black hole physics"
Now showing items 1-20 of 61
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3-Cm Fine Structure Masers: A Unique Signature of Supermassive Black Hole Formation via Direct Collapse in the Early Universe
(American Astronomical Society, 2016)The direct collapse black hole (DCBH) scenario describes the isothermal collapse of a pristine gas cloud directly into a massive, M_BH=10^4-10^6 M_sun black hole. In this paper we show that large HI column densities of ... -
The Black Hole Mass Distribution in the Galaxy
(IOP Publishing, 2010)We use dynamical mass measurements of 16 black holes in transient low-mass X-ray binaries to infer the stellar black hole mass distribution in the parent population. We find that the observations are best described by a ... -
Black Hole Spin and the Radio Loud/Quiet Dichotomy of Active Galactic Nuclei
(IOP Publishing, 2010)Radio loud active galactic nuclei (AGNs) are on average 1000 times brighter in the radio band compared to radio quiet AGNs. We investigate whether this radio loud/quiet dichotomy can be due to differences in the spin of ... -
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets
(Springer Science + Business Media, 2013)The spins of ten stellar black holes have been measured using the continuum- fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another ... -
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 circular polarization of Sagittarius A* at submillimeter wavelengths
(IOP Publishing, 2012)We report the first detections of circularly polarized emission at submillimeter wavelengths from the compact radio source and supermassive black hole candidate Sgr A* at a level of 1.2% ± 0.3% at 1.3 mm wavelength (230 ... -
Confirmation via the Continuum-Fitting Method That the Spin of the Black Hole in Cygnus X-1 Is Extreme
(IOP Publishing, 2014)In Gou et al., we reported that the black hole primary in the X-ray binary Cygnus X-1 is a near-extreme Kerr black hole with a spin parameter a∗ > 0.95 (3σ). We confirm this result while setting a new and more stringent ... -
The constant inner-disk radius of LMC X-3: A basis for measuring black hole spin
(IOP Publishing, 2010)he black hole binary system LMC X-3 has been observed by virtually every X-ray mission since the inception of X-ray astronomy. Among the persistent sources, LMC X-3 is uniquely both habitually soft and highly variable. ... -
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 ... -
Detecting stars at the galactic centre via synchrotron emission
(Oxford University Press (OUP), 2015)Stars orbiting within 1$\arcsec$ of the supermassive black hole in the Galactic Centre, Sgr A*, are notoriously difficult to detect due to obscuration by gas and dust. We show that some stars orbiting this region may be ... -
Detecting Triple Systems With Gravitational Wave Observations
(American Astronomical Society, 2017)The Laser Interferometer Gravitational Wave Observatory (LIGO) has recently discovered gravitational waves (GWs) emitted by merging black hole binaries. We examine whether future GW detections may identify triple companions ... -
A Determination of the Spin of the Black Hole Primary in LMC X-1
(IOP Publishing, 2009)The first extragalactic X-ray binary, LMC X-1, was discovered in 1969. In the 1980s, its compact primary was established as the fourth dynamical black hole candidate. Recently, we published accurate values for the mass of ... -
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 ... -
Double-peaked narrow-line signatures of dual supermassive black holes in galaxy merger simulations
(Oxford University Press (OUP), 2013)We present a first attempt to model the narrow-line (NL) region of active galactic nuclei (AGN) in hydrodynamic simulations of galaxy mergers, using a novel physical prescription. This model is used to determine the origin ... -
Efficiency of Magnetic to Kinetic Energy Conversion in a Monopole Magnetosphere
(IOP Publishing, 2009)Unconfined relativistic outflows from rotating, magnetized compact objects are often well modeled by assuming that the field geometry is approximately a split-monopole at large radii. Earlier work has indicated that such ... -
Efficient generation of jets from magnetically arrested accretion on a rapidly spinning black hole
(Oxford University Press (OUP), 2011)We describe global, 3D, time‐dependent, non‐radiative, general‐relativistic, magnetohydrodynamic simulations of accreting black holes (BHs). The simulations are designed to transport a large amount of magnetic flux to the ... -
Erratum: "Precise Measurement of the Spin Parameter of the Stellar-Mass Black hole M33 X-7” (2008, ApJ, 679, L37)
(IOP Publishing, 2010)In prior work, 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 orbital inclination angle of unprecedented accuracy. ... -
The Event Horizon of M87
(IOP Publishing, 2015)The 6 × 109M⊙ supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event Horizon Telescope have localized the emission from the ... -
The event horizon of Sagittarius A*
(IOP Publishing, 2009)Black hole event horizons, causally separating the external universe from compact regions of spacetime, are one of the most exotic predictions of general relativity. Until recently, their compact size has prevented efforts ... -
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 ...