Radiative efficiency of collisionless accretion

Andrei V. Gruzinov

doi:10.1086/305845

Radiative efficiency of collisionless accretion

Andrei V. Gruzinov

Research output: Contribution to journal › Article › peer-review

Abstract

The radiative efficiency, η ≡ L/Ṁc², of a slowly accreting black hole is estimated using a two-temperature model of accretion. The radiative efficiency depends on the magnetic field strength near the Schwarzschild radius. For weak magnetic fields, i.e., β^-1 ≡ B²/8πp ≲ 10^-3, the low efficiency η ∼ 10^-4 that is assumed in some theoretical models is achieved. For β^-1 > 10^-3, a significant fraction of viscous heat is dissipated by electrons and radiated away resulting in η > 10^-4. At equipartition magnetic fields, β^-1 ∼ 1, we estimate η ∼ 10^-1.

Original language	English (US)
Pages (from-to)	787-791
Number of pages	5
Journal	Astrophysical Journal
Volume	501
Issue number	2 PART 1
DOIs	https://doi.org/10.1086/305845
State	Published - Jul 10 1998

Keywords

Accretion, accretion disks
Black hole physics
MHD
Turbulence

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/305845

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abstract = "The radiative efficiency, η ≡ L/Ṁc2, of a slowly accreting black hole is estimated using a two-temperature model of accretion. The radiative efficiency depends on the magnetic field strength near the Schwarzschild radius. For weak magnetic fields, i.e., β-1 ≡ B2/8πp ≲ 10-3, the low efficiency η ∼ 10-4 that is assumed in some theoretical models is achieved. For β-1 > 10-3, a significant fraction of viscous heat is dissipated by electrons and radiated away resulting in η > 10-4. At equipartition magnetic fields, β-1 ∼ 1, we estimate η ∼ 10-1.",

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N2 - The radiative efficiency, η ≡ L/Ṁc2, of a slowly accreting black hole is estimated using a two-temperature model of accretion. The radiative efficiency depends on the magnetic field strength near the Schwarzschild radius. For weak magnetic fields, i.e., β-1 ≡ B2/8πp ≲ 10-3, the low efficiency η ∼ 10-4 that is assumed in some theoretical models is achieved. For β-1 > 10-3, a significant fraction of viscous heat is dissipated by electrons and radiated away resulting in η > 10-4. At equipartition magnetic fields, β-1 ∼ 1, we estimate η ∼ 10-1.

AB - The radiative efficiency, η ≡ L/Ṁc2, of a slowly accreting black hole is estimated using a two-temperature model of accretion. The radiative efficiency depends on the magnetic field strength near the Schwarzschild radius. For weak magnetic fields, i.e., β-1 ≡ B2/8πp ≲ 10-3, the low efficiency η ∼ 10-4 that is assumed in some theoretical models is achieved. For β-1 > 10-3, a significant fraction of viscous heat is dissipated by electrons and radiated away resulting in η > 10-4. At equipartition magnetic fields, β-1 ∼ 1, we estimate η ∼ 10-1.

KW - Accretion, accretion disks

KW - Black hole physics

KW - MHD

KW - Turbulence

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JF - Astrophysical Journal

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ER -

Radiative efficiency of collisionless accretion

Abstract

Keywords

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