Molecular outflow and feedback in the obscured Quasar XID2028 revealed by ALMA

Brusa, M, Cresci, G, Daddi, E, Paladino, R, Perna, M, Bonigiorno, A, Lusso, E, Sargent, M T and others, (2018) Molecular outflow and feedback in the obscured Quasar XID2028 revealed by ALMA. Astronomy and Astrophysics, 612 (A29). pp. 1-15. ISSN 0004-6361

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Abstract

We imaged with ALMA and ARGOS/LUCI the molecular gas and the dust and stellar continuum in XID2028, an obscured QSO at z=1.593, where the presence of a massive outflow in the ionized gas component traced by the [O III]5007 emission has been resolved up to 10 kpc. This target represents a unique test case to study QSO 'feedback in action' at the peak epoch of AGN-galaxy coevolution. The QSO has been detected in the CO(5-4) transition and in the 1.3mm continuum, at ~30 and ~20 {\sigma} significance respectively, with both emissions confined in the central (<4 kpc) radius area. Our analysis suggests the presence of a fast rotating molecular disc (v~400 km/s) on very compact scales, and well inside the galaxy extent seen in the rest-frame optical light (~10 kpc, as inferred from the LUCI data). Adding available measurements in additional two CO transitions, CO(2-1) and CO(3-2), we could derive a total gas mass of ~1010 M⊙, thanks to a critical assessment of CO excitation and the comparison with Rayleigh-Jeans continuum estimate. This translates into a very low gas fraction (<5%) and depletion time scales of 40-75 Myr, reinforcing the result of atypical gas consumption conditions in XID2028, possibly due to feedback effects on the host galaxy. Finally, we also detect at ~5{\sigma} the presence of high velocity CO gas, which we interpret as a signature of galaxy-scale molecular outflow, spatially coincident with the ionised gas outflow. XID2028 represents therefore a unique case where the measurement of total outflowing mass (~500-800 M⊙/yr) including the molecular and atomic components, in both the ionised and neutral phases, has been attempted for a high-z QSO.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Mark Sargent
Date Deposited: 20 Feb 2018 10:40
Last Modified: 04 Jul 2018 14:05
URI: http://sro.sussex.ac.uk/id/eprint/73717

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Project NameSussex Project NumberFunderFunder Ref
10 billion years of galaxy evolution: establishing the links between star-formation and cold gas reservoirsG1946ROYAL SOCIETYLT150041