The Dragonfly Galaxy: II. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z = 2
dc.contributor.author | Emonts, B. | |
dc.contributor.author | De Breuck, C. | |
dc.contributor.author | Lehnert, M. | |
dc.contributor.author | Vernet, J. | |
dc.contributor.author | Gullberg, B. | |
dc.contributor.author | Villar-Martin, M. | |
dc.contributor.author | Nesvadba, N. | |
dc.contributor.author | Drouart, G. | |
dc.contributor.author | Ivison, R. | |
dc.contributor.author | Seymour, Nick | |
dc.contributor.author | Wylezalek, D. | |
dc.contributor.author | Barthel, P. | |
dc.date.accessioned | 2017-01-30T10:58:58Z | |
dc.date.available | 2017-01-30T10:58:58Z | |
dc.date.created | 2016-01-18T20:00:45Z | |
dc.date.issued | 2015 | |
dc.identifier.citation | Emonts, B. and De Breuck, C. and Lehnert, M. and Vernet, J. and Gullberg, B. and Villar-Martin, M. and Nesvadba, N. et al. 2015. The Dragonfly Galaxy: II. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z = 2. Astronomy and Astrophysics. 584. | |
dc.identifier.uri | http://hdl.handle.net/20.500.11937/7309 | |
dc.identifier.doi | 10.1051/0004-6361/201526090 | |
dc.description.abstract |
The Dragonfly Galaxy (MRC 0152-209), at redshift z ~ 2, is one of the most vigorously star-forming radio galaxies in the Universe. What triggered its activity? We present ALMA Cycle 2 observations of cold molecular CO(6−5) gas and dust, which reveal that this is likely a gas-rich triple merger. It consists of a close double nucleus (separation ~4 kpc) and a weak CO-emitter at ~10 kpc distance, all of which have counterparts in HST/NICMOS imagery. The hyper-luminous starburst and powerful radio-AGN were triggered at this precoalescent stage of the merger. The CO(6−5) traces dense molecular gas in the central region, and complements existing CO(1−0) data, which reveal more widespread tidal debris of cold gas. We also find ~1010 M☉ of molecular gas with enhanced excitation at the highest velocities. At least 20−50% of this high-excitation, high-velocity gas shows kinematics that suggests it is being displaced and redistributed within the merger, although with line-of-sight velocities of |v| < 500 km s-1, this gas will probably not escape the system. The processes that drive the redistribution of cold gas are likely related to either the gravitational interaction between two kpc-scale discs, or starburst/AGN-driven outflows. We estimate that the rate at which the molecular gas is redistributed is at least [Ṁentity!#x2009!]~ 1200 ± 500 M☉ yr-1, and could perhaps even approach the star formation rate of ~3000 ± 800 M☉ yr-1. The fact that the gas depletion and gas redistribution timescales are similar implies that dynamical processes can be important in the evolution of massive high-z galaxies. | |
dc.title | The Dragonfly Galaxy: II. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z = 2 | |
dc.type | Journal Article | |
dcterms.source.volume | 584 | |
dcterms.source.issn | 0004-6361 | |
dcterms.source.title | Astronomy and Astrophysics | |
curtin.note |
Reproduced with permission from Astronomy & Astrophysics, © ESO | |
curtin.department | Department of Physics and Astronomy | |
curtin.accessStatus | Open access |