Radiation Spectra from Advection-dominated Accretion Flows in a Global Magnetic Field

We calculate the radiation spectra from advection-dominated accretion flows (ADAFs), taking into account the effects of a global magnetic field. Our calculation is based on the analytic model for magnetized ADAFs proposed by Kaburaki, in which a large-scale magnetic field controls the accretion process. Adjusting a few parameters, we find that our model can well reproduce the observed spectrum of Sagittarius A*. The result is discussed in comparison with those of well-known ADAF models, in which the turbulent viscosity controls the accretion process.

[1]  O. Kaburaki.  Analytic Model for Advection-dominated Accretion Flows in a Global Magnetic Field , 1999, astro-ph/9910252.

[2]  E. Quataert,et al.  Spectral Models of Advection-dominated Accretion Flows with Winds , 1998, astro-ph/9810136.

[3]  Roger D. Blandford,et al.  On the fate of gas accreting at a low rate on to a black hole , 1998, astro-ph/9809083.

[4]  R. Mahadevan,et al.  Probing the two-temperature paradigm: observational tests for the basic assumptions in advection-dominated accretion flows , 1998, astro-ph/9808271.

[5]  S. Mineshige,et al.  Black-Hole Accretion Disks , 1999 .

[6]  Edinburgh,et al.  Strong observational constraints on advection-dominated accretion in the cores of elliptical galaxies , 1998, astro-ph/9807245.

[7]  S. Mineshige,et al.  Spectrum of Optically Thin Advection-dominated Accretion Flow around a Black Hole: Application to Sagittarius A* , 1997, astro-ph/9708234.

[8]  M. Kusunose,et al.  Optically Thin, Advection-Dominated Two-Temperature Disks , 1997 .

[9]  Jonathan E. Grindlay,et al.  Advection-dominated Accretion Model of Sagittarius A*: Evidence for a Black Hole at the Galactic Center , 1997, astro-ph/9706112.

[10]  R. Lovelace,et al.  Influence of Ohmic Heating on Advection-dominated Accretion Flows , 1997, astro-ph/9704208.

[11]  Julian Krolik,et al.  Gamma-Ray Emission from Advection-dominated Accretion Flows around Black Holes: Application to the Galactic Center , 1997, astro-ph/9704018.

[12]  Reinhard Genzel,et al.  Stellar proper motions in the central 0.1 PC of the galaxy , 1997 .

[13]  R. Mahadevan,et al.  Scaling Laws for Advection-dominated Flows: Applications to Low-Luminosity Galactic Nuclei , 1996, astro-ph/9609107.

[14]  R. Narayan,et al.  Harmony in Electrons: Cyclotron and Synchrotron Emission by Thermal Electrons in a Magnetic Field , 1996, astro-ph/9601073.

[15]  G. Rieke,et al.  Stellar Kinematics and the Black Hole in the Galactic Center , 1996 .

[16]  Ramesh Narayan,et al.  Explaining the spectrum of Sagittarius A* with a model of an accreting black hole , 1995, Nature.

[17]  R. Narayan,et al.  Advection dominated accretion: Underfed black holes and neutron stars , 1994, astro-ph/9411059.

[18]  O. Regev,et al.  Thermal equilibria of accretion disks , 1994, astro-ph/9409018.

[19]  R. Narayan,et al.  Advection-dominated Accretion: Self-Similarity and Bipolar Outflows , 1994, astro-ph/9411058.

[20]  R. Narayan,et al.  Advection-dominated Accretion: A Self-similar Solution , 1994, astro-ph/9403052.

[21]  R. Blandford,et al.  Reaction rates and energy distributions for elementary processes in relativistic pair plasmas , 1990, Monthly Notices of the Royal Astronomical Society.

[22]  A. Zdziarski,et al.  Pair production and Compton scattering in compact sources and comparison to observations of active galactic nuclei , 1987 .

[23]  E. Phinney,et al.  Pair-induced spectral changes and variability in compact X-ray sources , 1986 .

[24]  D. Raine,et al.  Accretion power in astrophysics , 1985 .

[25]  M. Morris,et al.  Large, highly organized radio structures near the galactic centre , 1984, Nature.

[26]  F. C. Jones.  Calculated spectrum of inverse-Compton- scattered photons. , 1968 .