A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies

• Published in: Nature
• Main Authors: McDonald, M., Lueker, M., Padin, S., Vieira, J. D.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Nature Publishing Group 2012
• Subjects: Hubble; Kavli; South Pole; South pole
• Online Access: https://doi.org/10.1038/nature11379

In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10^(45) erg s^(−1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers. © 2012 Macmillan Publishers Limited. Received 05 April 2012; Accepted 12 July 2012; Published online 15 August 2012. M. McD. was supported at MIT by NASA through the Chandra X-ray Observatory. The South Pole Telescope is supported by the National Science Foundation, with partial support provided by the Kavli Foundation, and the Moore Foundation. Support for X-ray analysis was provided by NASA. Work at McGill University is supported by NSERC, the CRC programme, and CIfAR, and at Harvard University by the NSF. S.V. acknowledges a Senior NPP Award held at the NASA Goddard Space Flight Center. R.K. acknowledges a NASA Hubble Fellowship, B.A.B. acknowledges a KICP Fellowship, M.A.D. acknowledges an Alfred P. ...