The gentle monster PDS 456: the kpc scale molecular outflow and its implications for QSO feedback. (arXiv:1903.10528v1 [astro-ph.GA])

The gentle monster PDS 456: the kpc scale molecular outflow and its implications for QSO feedback. (arXiv:1903.10528v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bischetti_M/0/1/0/all/0/1">M. Bischetti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Piconcelli_E/0/1/0/all/0/1">E. Piconcelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feruglio_C/0/1/0/all/0/1">C. Feruglio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fiore_F/0/1/0/all/0/1">F. Fiore</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carniani_S/0/1/0/all/0/1">S. Carniani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brusa_M/0/1/0/all/0/1">M. Brusa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cicone_C/0/1/0/all/0/1">C. Cicone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vignali_C/0/1/0/all/0/1">C. Vignali</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bongiorno_A/0/1/0/all/0/1">A. Bongiorno</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cresci_G/0/1/0/all/0/1">G. Cresci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mainieri_V/0/1/0/all/0/1">V. Mainieri</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maiolino_R/0/1/0/all/0/1">R. Maiolino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marconi_A/0/1/0/all/0/1">A. Marconi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nardini_E/0/1/0/all/0/1">E. Nardini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zappacosta_L/0/1/0/all/0/1">L. Zappacosta</a>

We report on the first ALMA observation of the CO(3$-$2) and rest-frame ~340
GHz continuum emission in PDS 456, which is the most luminous, radio-quiet QSO
in the local Universe ($z$~0.18), with a bolometric luminosity $L_{rm
Bol}sim10^{47}$ erg s$^{-1}$. 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$-$2) emission line, is distributed in a compact rotating disk,
with size of ~1.3 kpc, seen close to face-on ($i$~25 deg). Fast CO(3$-$2)
emission in the velocity range $vin[-1000,+500]$ km s$^{-1}$ is also present.
Specifically, we detect several blue-shifted clumps out to ~5 kpc from the
nucleus, in addition to a compact ($Rlesssim1.2$ kpc), broad emission
component. These components reveal a galaxy-wide molecular outflow, with a
total mass $M_{rm mol}^{rm out}sim2.5times10^8$ $M_{odot}$ and a mass
outflow rate $dot{M}_{rm mol}sim290$ $M_{odot}$ yr$^{-1}$. The
corresponding depletion time is ~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. $L_{rm
Bol}/c$) is $lesssim1$, 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 AGN so far. We suggest three possible scenarios that
may explain this observation: (i) in very luminous AGN 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
ISM (iii) AGN radiation pressure may play an important role in driving the
outflow.

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