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Large-scale outflows in galaxies

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journal contribution
posted on 24.10.2012, 09:06 by K. Zubovas, C. Power
We discuss massive outflows in galaxy bulges, particularly the ones driven by accretion episodes where the central supermassive black hole reaches the Eddington limit. We show that the quasar radiation field Compton-cools the wind shock until this reaches distances ∼1 kpc from the black hole, but becomes too dilute to do this at larger radii. Radiative processes cannot cool the shocked gas within the flow time at any radius. Outflows are therefore momentum driven at small radii (as required to explain the M—σ relation). At large radii, they are energy driven, contrary to recent claims. We solve analytically the motion of an energy-driven shell after the central source has turned off. This shows that the thermal energy in the shocked wind can drive further expansion for a time ∼10 times longer than the active time of the central source. Outflows observed at large radii with no active central source probably result from an earlier short (few Myr) active phase of this source.

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Citation

Monthly Notices of the Royal Astronomical Society Letters, 2011, 415 (1)

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VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society Letters

Publisher

Oxford University Press (OUP)

issn

1745-3933

Copyright date

2011

Available date

24/10/2012

Publisher version

http://mnrasl.oxfordjournals.org/content/415/1/L6

Language

en

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