|
Description
DYNAMO is a multiwavelength, spatially resolved survey of local (z~0.1) star-forming galaxies designed to study evolution through comparison with samples at z=~2. Half of the sample has integrated H{alpha luminosities of >10^42^erg/s, the typical lower limit for resolved spectroscopy at z=~2. The sample covers a range in stellar mass (10^9^-10^11^M_{sun_) and star formation rate (0.2-100M_{sun}_/yr). In this first paper of a series, we present integral-field spectroscopy of H{alpha emission for the sample of 67 galaxies. We infer gas fractions in our sample as high as =~0.8, higher than typical for local galaxies. Gas fraction correlates with stellar mass in galaxies with star formation rates below 10M_{sun}_/yr, as found by COLDGASS, but galaxies with higher star formation rates have higher than expected gas fractions. There is only a weak correlation, if any, between gas fraction and gas velocity dispersion. Galaxies in the sample visually classified as disc-like are offset from the local stellar mass Tully-Fisher relation to higher circular velocities, but this offset vanishes when both gas and stars are included in the baryonic Tully-Fisher relation. The mean gas velocity dispersion of the sample is =~50km/s, and V/{sigma} ranges from 2 to 10 for most of the discs, similar to 'turbulent' galaxies at high redshift. Half of our sample show disc-like rotation, while ~20 percent show no signs of rotation. The division between rotating and non-rotating is approximately equal for the sub-samples with either star formation rates >10M_{sun}_/yr, or specific star formation rates typical of the star formation 'main sequence' at z=~2. Across our whole sample, we find good correlation between the dominance of `turbulence' in galaxy discs (as expressed by V/{sigma}) and gas fraction as has been predicted for marginally stable Toomre discs. Comparing our sample with many others at low- and high-redshift reveals a correlation between gas velocity dispersion and star formation rate. These findings suggest the DYNAMO discs are excellent candidates for local galaxies similar to turbulent z=~2 disc galaxies.
|
