Details

Autor(en) / Beteiligte

• Hanish, D. J
• Meurer, G. R
• Ferguson, H. C
• Zwaan, M. A
• Heckman, T. M
• Staveley-Smith, L
• Bland-Hawthorn, J
• Kilborn, V. A
• Koribalski, B. S
• Putman, M. E
• Ryan-Weber, E. V
• Oey, M. S
• Kennicutt, Jr., R. C
• Knezek, P. M
• Meyer, M. J
• Smith, R. C
• Webster, R. L
• Dopita, M. A
• Doyle, M. T
• Drinkwater, M. J
• Freeman, K. C
• Werk, J. K

Titel

The Survey for Ionization in Neutral Gas Galaxies. II. The Star Formation Rate Density of the Local Universe

Ist Teil von

• The Astrophysical journal, 2006-09, Vol.649 (1), p.150-162

Ort / Verlag

Chicago, IL: IOP Publishing

Erscheinungsjahr

2006

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We derive observed Ha and R-band luminosity densities of an H I-selected sample of nearby galaxies using the SINGG sample to be l super('Ha) = (9.4c1.8) x 10 super(38) h sub(70) ergs s super(-1) Mpc super(-3) for Ha and l super('R) = (4.4 c 0.7) x 10 super(37) h sub(70) ergs s super(-1) AA super(-1) Mpc super(-3) in the R band. This R-band luminosity density is approximately 70% of that found by the Sloan Digital Sky Survey. This leads to a local star formation rate density of log( sub(SFR) [M sub( )yr super(-1) Mpc super(-3)]) = -1.80 super(+0.13 -0.07) (random) c0.03(systematic) + log(h sub(70)) after applying a mean internal extinction correction of 0.82 mag. The gas cycling time of this sample is found to be t sub(gas) = 7.5 super(+1.3 -2.1) Gyr, and the volume-averaged equivalent width of the SINGG galaxies is EW(Ha) =28.8 super(+7.2 -4.7) AA (21.2 super(+4.2 -3.5) AA without internal dust correction). As with similar surveys, these results imply that sub(SFR)(z) decreases drastically from z 6 1.5 to the present. A comparison of the dynamical masses of the SINGG galaxies evaluated at their optical limits with their stellar and H I masses shows significant evidence of downsizing: the most massive galaxies have a larger fraction of their mass locked up in stars compared with H I, while the opposite is true for less massive galaxies. We show that the application of the Kennicutt star formation law to a galaxy having the median orbital time at the optical limit of this sample results in a star formation rate decay with cosmic time similar to that given by the sub(SFR)(z) evolution. This implies that the sub(SFR)(z) evolution is primarily due to the secular evolution of galaxies, rather than interactions or mergers. This is consistent with the morphologies predominantly seen in the SINGG sample.