%0 Journal Article
%T The gentle monster PDS 456 - Kiloparsec-scale molecular outflow and its implications for QSO feedback
%A A. Bongiorno
%A A. Marconi
%A C. Cicone
%A C. Feruglio
%A C. Vignali
%A E. Nardini
%A E. Piconcelli
%A F. Fiore
%A G. Cresci
%A L. Zappacosta
%A M. Bischetti
%A M. Brusa
%A R. Maiolino
%A S. Carniani
%A V. Mainieri
%J -
%D 2019
%R 10.1051/0004-6361/201935524
%X We report on the first ALMA observation of the CO(3£¿2) and rest-frame ¡«340 GHz continuum emission in PDS 456, which is the most luminous, radio-quiet QSO in the local Universe (<i>z<i/>£¿£¿£¿0.18), with a bolometric luminosity <i>L<i/><sub>Bol<sub/>£¿¡«£¿10<sup>47<sup/> erg s<sup>£¿1<sup/>. ALMA angular resolution allowed us to map scales as small as ¡«700 pc. The molecular gas reservoir traced by the core of the very bright CO(3£¿2) emission line is distributed in a compact rotating disk, with a size of ¡«1.3 kpc, seen close to face-on (<i>i<i/>£¿¡«£¿25 deg). Fast CO(3£¿2) emission in the velocity range <i>v<i/>£¿¡Ê£¿[£¿£¿£¿1000,£¿500] km s<sup>£¿1<sup/> is also present. Specifically, we detect several blue-shifted clumps out to ¡«5 kpc from the nucleus, in addition to a compact (<i>R<i/>£¿£¿£¿1.2 kpc), broad emission component. These components reveal a galaxy-wide molecular outflow, with a total mass (for an <i>¦Á<i/><sub>CO<sub/>£¿=£¿0.8£¿<i>M<i/><sub>¡Ñ<sub/> (K km s<sup>£¿1<sup/> pc<sup>2<sup/>)<sup>£¿1<sup/>) and a mass outflow rate <i>£¿<i/><sub>mol<sub/> ¡« 290 <i>M<i/><sub>¡Ñ<sub/> yr<sup>£¿1<sup/>. The corresponding depletion time is <i>¦Ó<i/><sub>dep<sub/>£¿¡«£¿8 Myr, shorter than the rate at which the molecular gas is converted into stars, indicating that the detected outflow is potentially able to quench star-formation in the host. The momentum flux of the molecular outflow normalised to the radiative momentum output (i.e. <i>L<i/><sub>Bol<sub/>/<i>c<i/>) is £¿1, comparable to that of the X-ray ultra-fast outflow (UFO) detected in PDS 456. This is at odds with the expectations for an energy-conserving expansion suggested for most of the large-scale outflows detected in low-luminosity AGNs so far. We suggest three possible scenarios that may explain this observation: (i) in very luminous AGNs such as our target the molecular gas phase is tracing only a fraction of the total outflowing mass; (ii) a small coupling between the shocked gas by the UFO and the host-galaxy interstellar medium (ISM); and (iii) AGN radiation pressure may be playing an important role in driving the outflow
%U https://www.aanda.org/articles/aa/full_html/2019/08/aa35524-19/aa35524-19.html