Herschel-ATLAS and ALMA: HATLAS J142935.3-002836, a lensed major merger at redshift 1.027

Messias, Hugo and Dye, S. and Nagar, Neil and Orellana, Gustavo and Shane Bussmann, R. and Calanog, Jae and Dannerbauer, Helmut and Fu, Hai and Ibar, Edo and Inohara, Andrew and Ivison, R.J. and Negrello, Mattia and Riechers, Dominik A. and Sheen, Yun-Kyeong and Aguirre, James E. and Amber, Simon and Birkinshaw, Mark and Bourne, Nathan and Bradford, Charles M. and Clements, Dave L. and Cooray, Asantha and De Zotti, Gianfranco and Demarco, Ricardo and Dunne, Loretta and Eales, Stephen and Fleuren, Simone and Kamenetzky, Julia and Lupu, Roxana E. and Maddox, Steve J. and Marrone, Daniel P. and Michałowski, Michał J. and Murphy, Eric J. and Nguyen, Hien T. and Omont, Alain and Rowlands, Kate and Smith, Dan and Smith, Matt and Valiante, Elisabetta and Vieira, Joaquin D. (2014) Herschel-ATLAS and ALMA: HATLAS J142935.3-002836, a lensed major merger at redshift 1.027. Astronomy & Astrophysics, 568 . A92/1-A92/20. ISSN 1432-0746

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Context. The submillimetre-bright galaxy population is believed to comprise, aside from local galaxies and radio-loud sources, intrinsically active star-forming galaxies, the brightest of which are lensed gravitationally. The latter enable studies at a level of detail beyond what is usually possible by the observation facility.

Aims. This work focuses on one of these lensed systems, HATLAS J142935.3−002836 (H1429−0028), selected in the Herschel-ATLAS field. Gathering a rich, multi-wavelength dataset, we aim to confirm the lensing hypothesis and model the background source’s morphology and dynamics, as well as to provide a full physical characterisation.

Methods. Multi-wavelength high-resolution data is utilised to assess the nature of the system. A lensing-analysis algorithm that simultaneously fits different wavebands is adopted to characterise the lens. The background galaxy dynamical information is studied by reconstructing the 3D source plane of the ALMA CO (J:4 → 3) transition. Near-IR imaging from HST and Keck-AO allows to constrain rest-frame optical photometry independently for the foreground and background systems. Physical parameters (such as stellar and dust masses) are estimated via modelling of the spectral energy distribution taking source blending, foreground obscuration, and differential magnification into account.

Results. The system comprises a foreground edge-on disk galaxy (at zsp = 0.218) with an almost complete Einstein ring around it. The background source (at zsp = 1.027) is magnified by a factor of μ ~ 8−10 depending on wavelength. It is comprised of two components and a tens-of-kpc-long tidal tail resembling the Antennæ merger. As a whole, the background source is a massive stellar system (1.32-0.41+ 0.63 × 1011 M⊙) forming stars at a rate of 394 ± 90  M⊙ yr-1, and it has a significant gas reservoir MISM = 4.6 ± 1.7 × 1010 M⊙. Its depletion time due to star formation alone is thus expected to be τSF = MISM/ SFR = 117 ± 51 Myr. The dynamical mass of one of the components is estimated to be 5.8 ± 1.7 × 1010 M⊙, and, together with the photometric total mass estimate, it implies that H1429−0028 is a major merger system (1:2.8-1.5+1.8).

Item Type: Article
Additional Information: © ESO, 2014
Keywords: gravitational lensing: strong; galaxies: ISM; galaxies: kinematics and dynamics
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1051/0004-6361/201424410
Depositing User: Eprints, Support
Date Deposited: 02 May 2017 13:03
Last Modified: 02 May 2017 19:59
URI: http://eprints.nottingham.ac.uk/id/eprint/42451

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