We show that the ultraviolet absorption features, newly discovered in Hubble Space Telescope spectra, are consistent with being formed in a layer that extends a few kpc above the disk of the Milky Way. In this interface between the disk and the Galactic corona, high-metallicity gas ejected from the disk by supernova feedback can mix efficiently with the virial-temperature coronal material. The mixing process triggers the cooling of the lower corona down to temperatures encompassing the characteristic range of the observed absorption features, producing a net supernova-driven gas accretion onto the disk at a rate of a few Msun/yr. We speculate that this mechanism explains how the hot mode of cosmological accretion feeds star formation in galactic disks.

Ionized Absorbers as Evidence for Supernova-driven Cooling of the Lower Galactic Corona

FRATERNALI, FILIPPO;MARASCO, ANTONINO;F. Marinacci;
2013

Abstract

We show that the ultraviolet absorption features, newly discovered in Hubble Space Telescope spectra, are consistent with being formed in a layer that extends a few kpc above the disk of the Milky Way. In this interface between the disk and the Galactic corona, high-metallicity gas ejected from the disk by supernova feedback can mix efficiently with the virial-temperature coronal material. The mixing process triggers the cooling of the lower corona down to temperatures encompassing the characteristic range of the observed absorption features, producing a net supernova-driven gas accretion onto the disk at a rate of a few Msun/yr. We speculate that this mechanism explains how the hot mode of cosmological accretion feeds star formation in galactic disks.
Filippo Fraternali; A. Marasco; F. Marinacci; J. Binney
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/134312
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