Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy

• Published in: Nature (London) 2014-12, Vol.516 (7529), p.68-70
• Main Authors: Geach, J. E., Hickox, R. C., Diamond-Stanic, A. M., Krips, M., Rudnick, G. H., Tremonti, C. A., Sell, P. H., Coil, A. L., Moustakas, J.
• Format: Article
• Language: English
• Subjects: 639/33; Cold; Galaxies; Humanities and Social Sciences; Kinetic energy; letter; multidisciplinary; Observations; Science; Space telescopes; Star & galaxy formation; Star formation; Starburst galaxies; Stars; Stars & galaxies; Wind
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature14012

A high-velocity outflow of molecular gas from a starburst galaxy has been observed to extend about ten kiloparsecs; its velocity is consistent with the momentum flux from stellar radiation pressure, showing that bursts of star formation can eject large amounts of cold gas from the central regions of galaxies, curtailing star formation. Self-limiting nature of star formation SDSS J0905+57 is a compact massive starburst galaxy at a redshift of 0.7 that is driving a wind with one of the highest velocities known for any star-forming galaxy. Radio astronomical observations of this galaxy in the 2-millimetre waveband now indicate a high-velocity outflow of 35% of the total molecular gas extending about ten kiloparsecs, with a velocity consistent with the momentum flux from stellar radiation pressure. Previously known outflows from such galaxies had extended less than a kiloparsec and involved only a small fraction of total molecular gas. This new finding suggests that bursts of star formation can eject large amounts of cold gas — the raw material for star formation — from the central regions of a galaxy, thereby limiting the growth of stellar mass through a simple feedback mechanism. Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure 1 , 2 . Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and have typical scales of less than a kiloparsec 1 , 2 . In at least some cases, input from active galactic nuclei is dynamically important 2 , 3 , so pure stellar feedback (the momentum return into the interstellar medium) has been considered incapable of rapidly terminating star formation on galactic scales. Molecular gas has been detected outside the galactic plane of the archetypal starburst galaxy M82 (refs 4 and 5 ), but so far there has been no evidence that starbursts can propel substantial quantities of cold molecular gas to the same galactocentric radius (about 10 kiloparsecs) as the warmer gas that has been traced by metal ion absorbers in the circumgalactic medium 6 , 7 . Here we report observations of molecular gas in a compact (effective radius 100 parsecs) massive starburst galaxy at redshift 0.7, which is known to drive a fast outflow of ionized gas 8 . We find that 35 per cent of the total molecular gas ext