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Title: | The gentle monster PDS 456. Kiloparsec-scale molecular outflow and its implications for QSO feedback | Authors: | BISCHETTI, MANUELA PICONCELLI, Enrico Feruglio, Chiara FIORE, Fabrizio Carniani, S. Brusa, M. CICONE, CLAUDIA Vignali, C. BONGIORNO, ANGELA CRESCI, GIOVANNI Mainieri, V. Maiolino, R. Marconi, Alessandro NARDINI, EMANUELE ZAPPACOSTA, Luca |
Issue Date: | 2019 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 628 | First Page: | A118 | Abstract: | 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<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 ∼ 25 deg). Fast CO(3-2) emission in the velocity range v ∈ [ - 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 (R ≲ 1.2 kpc), broad emission component. These components reveal a galaxy-wide molecular outflow, with a total mass M<SUB>mol</SUB><SUP>out</SUP> ∼ 2.5 × 10<SUP>8</SUP> M<SUB>☉</SUB> (for an α<SUB>CO</SUB> = 0.8 M<SUB>☉</SUB> (K km s<SUP>-1</SUP> pc<SUP>2</SUP>)<SUP>-1</SUP>) and a mass outflow rate Ṁ<SUB>mol</SUB> ∼ 290 M<SUB>☉</SUB> yr<SUP>-1</SUP>. The corresponding depletion time is τ<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. L<SUB>Bol</SUB>/c) 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. | URI: | http://hdl.handle.net/20.500.12386/28983 | URL: | https://www.aanda.org/articles/aa/abs/2019/08/aa35524-19/aa35524-19.html | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201935524 | Bibcode ADS: | 2019A&A...628A.118B | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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Bischetti_1903.10528.pdf | postprint | 1.34 MB | Adobe PDF | View/Open |
Bischetti_aa35524-19.pdf | Pdf editoriale | 1.33 MB | Adobe PDF | View/Open |
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