Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes

  title={Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes},
  author={Rohta Takahashi},
  journal={The Astrophysical Journal},
  • R. Takahashi
  • Published 6 May 2004
  • Physics
  • The Astrophysical Journal
Can we determine the spin parameter of a black hole by observing the black hole's shadow on an accretion disk? To answer this question, we make qualitative and quantitative analyses of the shape and position of the shadow cast by a rotating black hole on an optically thick accretion disk and its dependence on the angular momentum of the black hole. We consider two types of inner edges of accretion disks, an event horizon and a marginally stable orbit. We have found black hole shadows of quite… 

Figures from this paper

Black Hole Shadows of Charged Spinning Black Holes
We propose a method for measuring the black hole charge by imaging a black hole shadow in a galactic center by future interferometers. Even when the black hole is uncharged, it is possible to confirm
Measuring the Spins of Accreting Black Holes
A typical galaxy is thought to contain tens of millions of stellar-mass black holes, the collapsed remnants of once massive stars, and a single nuclear supermassive black hole. Both classes of black
Anisotropic radiation field and trapped photons around the Kerr black hole
Aims. In order to understand the anisotropic properties of local radiation field in the curved spacetime around a rotating black hole, we investigate the appearance of a black hole seen by an
Foundations of Black Hole Accretion Disk Theory
This review covers the main aspects of black hole accretion disk theory and discusses how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere.
Iron line profiles and self-shadowing from relativistic thick accretion discs
We present Fe Ka line profiles from and images of relativistic discs with finite thickness around a rotating black hole using a novel code. The line is thought to be produced by iron fluorescence of
Visible Shapes of Black Holes M87* and SgrA*
We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal
Shadow of a rotating squashed Kaluza-Klein black hole
A bstractWe study the shadow of a rotating squashed Kaluza-Klein (KK) black hole and the shadow is found to possess distinct properties from those of usual rotating black holes. It is shown that the
Black Hole Spin Signature in the Black Hole Shadow of M87 in the Flaring State
Imaging the immediate vicinity of supermassive black holes (SMBH) and extracting a BH-spin signature is one of the grand challenges in astrophysics. M87 is known as one of the best targets for
Shadows of rotating five-dimensional charged EMCS black holes
Higher-dimensional theories admit astrophysical objects like supermassive black holes, which are rather different from standard ones, and their gravitational lensing features deviate from general


The effects of redshifts and focusing on the spectrum of an accretion disk around a Kerr black hole
The spectrum of X-rays produced by an accretion disk around a black hole is influenced markedly by Doppler shifts, gravitational redshifts, and the gravitational lens effect. These influences can be
The inner edge of the accretion disk around a supermassive black hole
Massive black holes are generally thought to exist at the centres of galaxies, but an unambiguous identification of a black hole has been impeded by a lack of evidence for the strong-field
Line Emission from an Accretion Disk Around a Black Hole: Effects of Disk Structure
The observed iron Kα fluorescence lines in Seyfert I galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. These lines serve as
Iron Fluorescence from within the Innermost Stable Orbit of Black Hole Accretion Disks
The fluorescent iron Kα line is a powerful observational probe of the inner regions of black hole accretion disks. Previous studies have assumed that only material outside the radius of marginal
Viewing the Shadow of the Black Hole at the Galactic Center.
In recent years, evidence for the existence of an ultracompact concentration of dark mass associated with the radio source Sagittarius A* in the Galactic center has become very strong. However,
Silhouette of a Dressed Black Hole
In the case of the traditional standard disk with an inner radius of 3 rg (three Schwarzschild radii) around the Schwarzschild black hole, there appears to be a dark central shadow with a radius of
Where Is the Inner Edge of an Accretion Disk around a Black Hole
What is meant by the "inner edge" of an accretion disk around a black hole depends on the property that defines the edge. We discuss four such definitions, using data from recent high-resolution
Gravitationally redshifted emission implying an accretion disk and massive black hole in the active galaxy MCG–6–30–15
ACTIVE galactic nuclei and quasars are probably powered by the accretion of gas onto a supermassive black hole at the centre of the host galaxy1, but direct confirmation of the presence of a black
Polarimetric Imaging of the Massive Black Hole at the Galactic Center
The radio source Sagittarius A* in the Galactic center emits a polarized spectrum at millimeter and submillimeter wavelengths that is strongly suggestive of relativistic disk accretion onto a massive
Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
High-resolution infrared observations of Sagittarius A* reveal ‘quiescent’ emission and several flares, and traces very energetic electrons or moderately hot gas within the innermost accretion region.