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Intermediate-mass black holes in dwarf galaxies: the case of Holmberg II


Mapelli, M (2007). Intermediate-mass black holes in dwarf galaxies: the case of Holmberg II. Monthly Notices of the Royal Astronomical Society, 376(3):1317-1326.

Abstract

In order to constrain the density of intermediate mass black holes (IMBHs) in galaxies, we run smoothed particle hydrodynamics (SPH) simulations of a gas-rich disc dwarf galaxy, where different halo and disc populations of IMBHs are embedded. IMBHs, when passing through dense gas regions, can accrete gas and switch on as X-ray sources. We derive the luminosity distribution of simulated IMBHs, by assuming that they accrete at the Bondi-Hoyle rate. The X-ray distribution of simulated IMBHs has been compared with that of observed sources in the dwarf galaxy Holmberg II, chosen for its richness in gas, its small mass (compared to spiral galaxies) and the accuracy of the available X-ray measurements. Holmberg II also hosts one of the strongest IMBH candidates. From this comparison, we find that the density parameter of disc (halo) IMBHs must be Ω•≲ 10−5 Ωb (Ω•≲ 10−2 Ωb, where Ωb is the density parameter of baryons), for a radiative efficiency 10−3 and an IMBH mass of 104 M⊙. These constraints imply that a dwarf galaxy like Holmberg II cannot host more than 1 (1000) disc (halo) 104 M⊙ IMBHs

Abstract

In order to constrain the density of intermediate mass black holes (IMBHs) in galaxies, we run smoothed particle hydrodynamics (SPH) simulations of a gas-rich disc dwarf galaxy, where different halo and disc populations of IMBHs are embedded. IMBHs, when passing through dense gas regions, can accrete gas and switch on as X-ray sources. We derive the luminosity distribution of simulated IMBHs, by assuming that they accrete at the Bondi-Hoyle rate. The X-ray distribution of simulated IMBHs has been compared with that of observed sources in the dwarf galaxy Holmberg II, chosen for its richness in gas, its small mass (compared to spiral galaxies) and the accuracy of the available X-ray measurements. Holmberg II also hosts one of the strongest IMBH candidates. From this comparison, we find that the density parameter of disc (halo) IMBHs must be Ω•≲ 10−5 Ωb (Ω•≲ 10−2 Ωb, where Ωb is the density parameter of baryons), for a radiative efficiency 10−3 and an IMBH mass of 104 M⊙. These constraints imply that a dwarf galaxy like Holmberg II cannot host more than 1 (1000) disc (halo) 104 M⊙ IMBHs

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Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:530 Physics
Language:English
Date:11 April 2007
Deposited On:08 Nov 2018 17:49
Last Modified:08 Nov 2018 17:49
Publisher:Oxford University Press
ISSN:0035-8711
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1111/j.1365-2966.2007.11528.x
Related URLs:https://www.swissbib.ch/Search/Results?lookfor=nationallicenceoxford101111j13652966200711528x (Library Catalogue)

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