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 / Filippo Fraternali; A. Marasco; F. Marinacci; J. Binney. - In: THE ASTROPHYSICAL JOURNAL LETTERS. - ISSN 2041-8205. - STAMPA. - 764:(2013), pp. 21-25. [10.1088/2041-8205/764/2/L21]
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.