Dark Matter Fraction in z~1 Star-Forming Galaxies

We present a observational study of the dark matter fraction in 225 rotation supported star-forming galaxies at $zapprox 0.9$ having stellar mass range: $ 9.0 leq log(M_* mathrm{M_odot}) leq 11.0$ and star formation rate: $0.49 leq log left(SFR mathrm{[M_{odot} yr^{-1}]} right) leq 1.77$. This is a sub sample of KMOS redshift one spectroscopic survey (KROSS) previously studied by citet{GS20}. The stellar masses ($M_*$) of these objects were previously estimated using mass-to-light ratios derived from fitting the spectral energy distribution of the galaxies. Star formation rates were derived from the H$_alpha$ luminosities. The total gas masses ($M_{gas}$) are determined by scaling relations of molecular and atomic gas citep[][respectively] {Tacconi2018, Lagos2011}. The dynamical masses ($M_{dyn}$) are directly derived from the rotation curves (RCs) at different scale lengths (effective radius: $R_e$, $sim 2 R_e$ and $sim 3 R_e$) and then the dark matter fractions ($f_{ DM }=1-M_{bar}/M_{dyn}$) at these radii are calculated. We report that at $zsim 1$ only a small fraction ($sim 5%$) of our sample has a low ($< 20%$) DM fraction within $sim$ 2-3 $R_e$. The majority ($> 72%$) of SFGs in our sample have dark matter dominated outer disks ($sim 5-10$ kpc) in agreement with local SFGs. Moreover, we find a large scatter in the fraction of dark matter at a given stellar mass (or circular velocity) with respect to local SFGs, suggesting that galaxies at $z sim 1$, a) span a wide range of stages in the formation of stellar disks, b) have diverse DM halo properties coupled with baryons.