2D kinematics and physical properties ofz ∼ 3star-forming galaxies

Abstract

We combined two-dimensional kinematic and morphology information on the Hα emission, obtained using near-infrared integral-field spectroscopy, with broad-band photometry to investigate the dynamical structure and the physical properties of a sample of 10 late-type galaxies at 1.0 ≲ z ≲ 1.5. Their star formation rate ranges from ~4 to ~400 M ⊙ yr -1 with a mean value of ~80 M ⊙ yr -1 . We found that three of these objects are undergoing a strong burst of star formation. The sample displays a range of kinematical types which include one merger, one face-on galaxy and eight objects showing evidence of rotation. Among these eight objects, half are rotation-dominated galaxies, while the rest are dispersion-dominated. We found also that two galaxies out of the rotation-dominated galaxies are pure rotationally supported discs. They achieve a maximum velocity of ~180-290 km s -1 within ~0.5-1 kpc, similar to local spirals with thin discs. Regarding the perturbed rotation and the dispersion-dominated galaxies, they display a plateau velocity range of 105-257 km s -1 , which is certainly underestimated due to beam smearing. However, their plateau radii (4.5-10.8 kpc) derived from our rotating disc model are significantly higher than those derived for pure rotating discs and local spiral galaxies. The galaxies of our sample have relatively young stellar populations (≲1.5 Gyr) and possess a range of stellar mass of 0.6-5 x 10 10 M ⊙ . In addition, most of them have not yet converted the majority of their gas into stars (six galaxies have their gas fraction >50 per cent). Therefore, those of them which already have a stable disc will probably have their final stellar mass similar to the present-day spirals, to which these rotating systems can be seen as precursors. We conclude our study by investigating the stellar mass Tully-Fisher relation at 1.2 ≲ z ≲ 1.5.