B. H. C. Emonts, I. Feain, H. J. A. Roettgering, G. Miley, N. Seymour, R. P. Norris, C. L. Carilli, M. Villar-Martin, M. Y. Mao, E. M. Sadler, R. D. Ekers, G. A. van Moorsel, R. J. Ivison, L. Pentericci, C. N. Tadhunter, D. J. Saikia
The high-redshift radio galaxy MRC 1138-262 (`Spiderweb Galaxy'; z = 2.16), is one of the most massive systems in the early Universe and surrounded by a dense `web' of proto-cluster galaxies. Using the Australia Telescope Compact Array, we detected CO(1-0) emission from cold molecular gas -- the raw ingredient for star formation -- across the Spiderweb Galaxy. We infer a molecular gas mass of M(H2) = 6x10^10 M(sun) (for M(H2)/L'(CO)=0.8). While the bulk of the molecular gas coincides with the central radio galaxy, there are indications that a substantial fraction of this gas is associated with satellite galaxies or spread across the inter-galactic medium on scales of tens of kpc. In addition, we tentatively detect CO(1-0) in the star-forming proto-cluster galaxy HAE 229, 250 kpc to the west. Our observations are consistent with the fact that the Spiderweb Galaxy is building up its stellar mass through a massive burst of widespread star formation. At maximum star formation efficiency, the molecular gas will be able to sustain the current star formation rate (SFR ~ 1400 M(sun)/yr, as traced by Seymour et al.) for about 40 Myr. This is similar to the estimated typical lifetime of a major starburst event in infra-red luminous merger systems.
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http://arxiv.org/abs/1301.6012
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