文章基本信息

标题：The gentle monster PDS 456
其他标题：Kiloparsec-scale molecular outflow and its implications for QSO feedback
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作者：M. Bischetti ; E. Piconcelli ; C. Feruglio 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：628
页码：1-12
DOI：10.1051/0004-6361/201935524
语种：English
出版社：EDP Sciences
摘要：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 luminosityLBol ∼ 1047erg 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 a size of ∼1.3 kpc, seen close to face-on (i ∼ 25 deg). Fast CO(3−2) emission in the velocity rangev ∈ [ − 1000, 500] km s−1is 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 massMmolout∼ 2.5 × 108M⊙(for anαCO = 0.8 M⊙(K km s−1pc2)−1) and a mass outflow rateṀmol∼ 290M⊙yr−1. The corresponding depletion time isτdep ∼ 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.LBol/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.
关键词：engalaxies: activequasars: individual: PDS 456galaxies: evolutionquasars: emission linestechniques: imaging spectroscopytechniques: interferometric