Herschel-ATLAS : a binary HyLIRG pinpointing a cluster of starbursting protoellipticals

Ivison, R.J.; Swinbank, A.M.; Smail, Ian; Harris, A.I.; Bussmann, R.S.; Cooray, A.; Cox, P.; Fu, H.; Kovács, A.; Krips, M.; Narayanan, D.; Negrello, M.; Neri, R.; Peñarrubia, J.; Richard, J.; Riechers, D.A.; Rowlands, K.; Staguhn, J.G.; Targett, T.A.; Amber, S.; Baker, A.J.; Bourne, N.; Bertoldi, F.; Bremer, M.; Calanog, J.A.; Clements, D.L.; Dannerbauer, H.; Dariush, A.; De Zotti, G.; Dunne, L.; Eales, S.A.; Farrah, D.; Fleuren, S.; Franceschini, A.; Geach, J.E.; George, R.D.; Helly, J.C.; Hopwood, R.; Ibar, E.; Jarvis, M.J.; Kneib, J.-P.; Maddox, S.; Omont, A.; Scott, D.; Serjeant, S.; Smith, M.W.L.; Thompson, M.A.; Valiante, E.; Valtchanov, I.; Vieira, J.; van der Wef, P.

Abstract

Panchromatic observations of the best candidate hyperluminous infrared galaxies from the widest Herschel extragalactic imaging survey have led to the discovery of at least four intrinsically luminous z = 2.41 galaxies across an ≈100 kpc region—a cluster of starbursting protoellipticals. Via subarcsecond interferometric imaging we have measured accurate gas and star formation surface densities. The two brightest galaxies span ~3 kpc FWHM in submillimeter/radio continuum and CO J = 4-3, and double that in CO J = 1-0. The broad CO line is due partly to the multitude of constituent galaxies and partly to large rotational velocities in two counter-rotating gas disks—a scenario predicted to lead to the most intense starbursts, which will therefore come in pairs. The disks have M dyn of several × 1011 M ☉, and gas fractions of ~40%. Velocity dispersions are modest so the disks are unstable, potentially on scales commensurate with their radii: these galaxies are undergoing extreme bursts of star formation, not confined to their nuclei, at close to the Eddington limit. Their specific star formation rates place them >~ 5 × above the main sequence, which supposedly comprises large gas disks like these. Their high star formation efficiencies are difficult to reconcile with a simple volumetric star formation law. N-body and dark matter simulations suggest that this system is the progenitor of a B(inary)-type ≈1014.6-M ☉ cluster.

Citation

Ivison, R., Swinbank, A., Smail, I., Harris, A., Bussmann, R., Cooray, A., …van der Wef, P. (2013). Herschel-ATLAS : a binary HyLIRG pinpointing a cluster of starbursting protoellipticals. Astrophysical Journal, 772(2), Article 137. https://doi.org/10.1088/0004-637x/772/2/137

• Journal Article Type: Article
• Publication Date: Jan 1, 2013
• Deposit Date: Aug 23, 2013
• Publicly Available Date: Sep 5, 2013
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 772
• Issue: 2
• Article Number: 137
• DOI: https://doi.org/10.1088/0004-637x/772/2/137
• Keywords: Galaxies, High-redshift, Starburst, Infrared, Radio continuum, Radio lines, Submillimeter.
• Public URL: https://durham-repository.worktribe.com/output/1479385