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Toward an Understanding of the Rapid Decline of the Cosmic Star Formation Rate

2005; IOP Publishing; Volume: 625; Issue: 1 Linguagem: Inglês

10.1086/429552

1538-4357

Eric F. Bell, Casey Papovich, Christian Wolf, E. Le Floc’h, J. A. R. Caldwell, M. Barden, Eiichi Egami, Daniel H. McIntosh, Klaus Meisenheimer, Pablo G. Pérez‐González, G. H. Rieke, Marcia Rieke, Jane R. Rigby, Hans‐Walter Rix,

Gamma-ray bursts and supernovae

We present a first analysis of deep 24 micron observations with the Spitzer Space Telescope of a sample of nearly 1500 galaxies in a thin redshift slice, 0.652x10^10 solar masses) are undergoing a period of intense star formation above their past-averaged SFR. In contrast, less than 1% of equally-massive galaxies in the local universe have similarly intense star formation activity. Morphologically-undisturbed galaxies dominate the total infrared luminosity density and SFR density: at z~0.7, more than half of the intensely star-forming galaxies have spiral morphologies, whereas less than \~30% are strongly interacting. Thus, a decline in major-merger rate is not the underlying cause of the rapid decline in cosmic SFR since z~0.7. Physical properties that do not strongly affect galaxy morphology - for example, gas consumption and weak interactions with small satellite galaxies - appear to be responsible.