THE PROPERTIES OF THE STAR-FORMING INTERSTELLAR MEDIUM ATz= 0.8–2.2 FROM HiZELS: STAR FORMATION AND CLUMP SCALING LAWS IN GAS-RICH, TURBULENT DISKS

Abstract

We present adaptive optics assisted integral field spectroscopy of nine H�-selected galaxies at z =0.84-2.23 drawn from the HiZELS narrow-band survey. Our observations map the kinematics of these star-forming galaxies on ∼kpc-scales. We demonstrate that within the ISM of these galaxies, the velocity dispersion of the star-forming gas (�) follows a scaling relation � ∝ � 1/n SFR +constant (whereSFR is the star formation surface density and the constant includes the stellar sur- face density). Assuming the disks are marginally stable (Toomre Q=1), this follows from the Kennicutt-Schmidt relation (�SFR =An), and we derive best fit parameters of n=1.34±0.15 and A=3.4 +2.5 −1.6 ×10 −4 M⊙ yr −1 kpc −2 , consistent with the local relation, and implying cold molecular gas masses of Mgas =10 9−10 M⊙ and molecular gas fractions Mgas /(Mgas +M⋆)=0.3±0.1, with a range of 10-75%. We also identify eleven ∼kpc-scale star-forming regions (clumps) within our sample and show that their sizes are comparable to the wavelength of the fastest growing mode. The luminosities and velocity dispersions of these clumps follow the same scaling relations as local Hii regions, although their star formation densities are a factor ∼15±5× higher than typically found locally. We discuss how the clump properties are related to the disk, and show that their high masses and luminosities are a consequence of the high disk surface density. Subject headings: galaxies: starburst, galaxies: evolution, galaxies: high-redshift