The FMOS-COSMOS Survey of Star-forming Galaxies at Z ∼ 1.6. V: Properties of Dark Matter Halos Containing Hα Emitting Galaxies

We study the properties of dark matter halos that contain star-forming galaxies at 1.43 ≤ z ≤ 1.74, using the FMOS-COSMOS survey. The sample consists of 516 objects with a detection of the Hα emission line, which represent the star forming population at this epoch, having a stellar mass range of 10^9.57 ≤ M _*/M _⊙ ≲ 10^11.4 and a star-formation rate range of 15 ≲ SFR/(M _⊙ yr⁻¹) ≲ 600. We measure the projected two-point correlation function while carefully taking into account observational biases, and find a significant clustering amplitude at scales of 0.04–10 h ⁻¹ cMpc, with a correlation length $r_0={5.26}_{-0.62}^{+0.75}{h}^{-1}cMpc$ and a bias $b={2.44}_{-0.32}^{+0.38}$. We interpret our clustering measurement using a halo occupation distribution model. The sample galaxies appear to reside in halos with mass $M_h={4.71}_{-1.62}^{+1.19}\times {10}^{12}{h}^{-1}{M}_{\odot }$ on average, which will likely become present-day halos of mass M _h (z = 0) ∼ 2 × 10¹³ h ⁻¹ M _⊙, equivalent to the typical halo mass scale of galaxy groups. We then confirm the decline of the stellar-to-halo mass ratio at M _h < 10¹² M _⊙, finding M _*/M _h ≈ 5 × 10⁻³ at M _h = 7. 5 × 10¹¹ M _⊙, which is lower by a factor of 2–4 than those measured at higher masses (M _h ∼ 10^12–13 M _⊙). Finally, we use our results to illustrate the future capabilities of Subaru's Prime-Focus Spectrograph, a next-generation instrument that will provide strong constraints on the galaxy-formation scenario by obtaining precise measurements of galaxy clustering at z > 1.