ACCRETION ONTO INTERMEDIATE-MASS BLACK HOLES REGULATED BY RADIATIVE FEEDBACK. I. PARAMETRIC STUDY FOR SPHERICALLY SYMMETRIC ACCRETION
- Department of Astronomy, University of Maryland, College Park, MD 20740 (United States)
We study the effect of radiative feedback on accretion onto intermediate-mass black holes (IMBHs) using the hydrodynamical code ZEUS-MP with a radiative transfer algorithm. In this paper, the first of a series, we assume accretion from a uniformly dense gas with zero angular momentum and extremely low metallicity. Our one-dimensional (1D) and 2D simulations explore how X-ray and UV radiation emitted near the black hole regulates the gas supply from large scales. Both 1D and 2D simulations show similar accretion rates and periods between peaks in accretion, meaning that the hydro-instabilities that develop in 2D simulations do not affect the mean flow properties. We present a suite of simulations exploring accretion across a large parameter space, including different radiative efficiencies and radiation spectra, black hole masses, density, and temperature, T{sub {infinity}}, of the neighboring gas. In agreement with previous studies, we find regular oscillatory behavior of the accretion rate, with duty cycle {approx}6%, mean accretion rate 3% (T{sub {infinity}}/10{sup 4} K){sup 2.5} of the Bondi rate and peak accretion {approx}10 times the mean for T{sub {infinity}} ranging between 3000 K and 15, 000 K. We derive parametric formulae for the period between bursts, the mean accretion rate, and the peak luminosity of the bursts and thus provide a formulation of how feedback-regulated accretion operates. The temperature profile of the hot ionized gas is crucial in determining the accretion rate, while the period of the bursts is proportional to the mean size of the Stroemgren sphere, and we find qualitatively different modes of accretion in the high versus low density regimes. We also find that a softer radiation spectrum produces a higher mean accretion rate. However, it is still unclear what the effect of a significant time delay is between the accretion rate at our inner boundary and the output luminosity. Such a delay is expected in realistic cases with non-zero angular momentum and may affect the time-dependent phenomenology presented here. This study is a first step to model the growth of seed black holes in the early universe and to make a prediction of the number and the luminosity of ultraluminous X-ray sources in galaxies produced by IMBHs accreting from the interstellar medium.
- OSTI ID:
- 21587551
- Journal Information:
- Astrophysical Journal, Vol. 739, Issue 1; Other Information: DOI: 10.1088/0004-637X/739/1/2; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
ALGORITHMS
BLACK HOLES
DENSITY
FEEDBACK
GALAXIES
HYDRODYNAMICS
LUMINOSITY
MASS
ONE-DIMENSIONAL CALCULATIONS
PARAMETRIC ANALYSIS
RADIANT HEAT TRANSFER
SIMULATION
TWO-DIMENSIONAL ELECTROPHORESIS
ULTRAVIOLET RADIATION
X RADIATION
ELECTROMAGNETIC RADIATION
ELECTROPHORESIS
ENERGY TRANSFER
FLUID MECHANICS
HEAT TRANSFER
IONIZING RADIATIONS
MATHEMATICAL LOGIC
MECHANICS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS