TY - JOUR
T1 - Cold molecular outflows in the local Universe and their feedback effect on galaxies
AU - Fluetsch, A.
AU - Maiolino, R.
AU - Carniani, S.
AU - Marconi, A.
AU - Cicone, C.
AU - Bourne, M. A.
AU - Costa, T.
AU - Fabian, A. C.
AU - Ishibashi, W.
AU - Venturi, G.
N1 - Publisher Copyright:
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2019/3/11
Y1 - 2019/3/11
N2 - We study molecular outflows in a sample of 45 local galaxies, both star forming and active galactic nucleus (AGN), primarily by using CO data from the Atacama Large Millimeter/submillimeter Array (ALMA) archive and from the literature. For a subsample, we also compare the molecular outflow with the ionized and neutral atomic phases. We infer an empirical analytical function relating the outflow rate simultaneously to the star formation rate (SFR), L AGN, and galaxy stellar mass; this relation is much tighter than the relations with the individual quantities. The outflow kinetic power shows a larger scatter than in previous, more biased studies, spanning from 0.1 to 5 per cent of L AGN, while the momentum rate ranges from 1 to 30 times L AGN /c, indicating that these outflows can be both energy driven, but with a broad range of coupling efficiencies with the interstellar medium (ISM), and radiation pressure driven. For about 10 per cent of the objects, the outflow energetics significantly exceed the maximum theoretical values; we interpret these as 'fossil outflows' resulting from activity of a past strong AGN, which has now faded. We estimate that, in the stellar mass range probed here (> 1010,M⊙), less than 5 per cent of the outflowing gas escapes the galaxy. The molecular gas depletion time associated with the outflow can be as short as a few million years in powerful AGN; however, the total gas (H2 + Hi) depletion times are much longer. Altogether, our findings suggest that even AGN-driven outflows might be relatively ineffective in clearing galaxies of their entire gas content, although they are likely capable of clearing and quenching the central region.
AB - We study molecular outflows in a sample of 45 local galaxies, both star forming and active galactic nucleus (AGN), primarily by using CO data from the Atacama Large Millimeter/submillimeter Array (ALMA) archive and from the literature. For a subsample, we also compare the molecular outflow with the ionized and neutral atomic phases. We infer an empirical analytical function relating the outflow rate simultaneously to the star formation rate (SFR), L AGN, and galaxy stellar mass; this relation is much tighter than the relations with the individual quantities. The outflow kinetic power shows a larger scatter than in previous, more biased studies, spanning from 0.1 to 5 per cent of L AGN, while the momentum rate ranges from 1 to 30 times L AGN /c, indicating that these outflows can be both energy driven, but with a broad range of coupling efficiencies with the interstellar medium (ISM), and radiation pressure driven. For about 10 per cent of the objects, the outflow energetics significantly exceed the maximum theoretical values; we interpret these as 'fossil outflows' resulting from activity of a past strong AGN, which has now faded. We estimate that, in the stellar mass range probed here (> 1010,M⊙), less than 5 per cent of the outflowing gas escapes the galaxy. The molecular gas depletion time associated with the outflow can be as short as a few million years in powerful AGN; however, the total gas (H2 + Hi) depletion times are much longer. Altogether, our findings suggest that even AGN-driven outflows might be relatively ineffective in clearing galaxies of their entire gas content, although they are likely capable of clearing and quenching the central region.
KW - galaxies: active
KW - galaxies: evolution
KW - galaxies: ISM
KW - galaxies: star formation
KW - quasars: general
UR - http://www.scopus.com/inward/record.url?scp=85062000962&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty3449
DO - 10.1093/mnras/sty3449
M3 - Article
AN - SCOPUS:85062000962
SN - 0035-8711
VL - 483
SP - 4586
EP - 4614
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -