The FMOS-COSMOS survey of star-forming galaxies at $z\sim 1.6$. V: Properties of dark matter halos containing H$\alpha$ emitting galaxies

Abstract

We study the properties of dark matter halos that contain star-forming galaxies at $1.43\le z\le 1.74$ using the FMOS-COSMOS survey. The sample consists of 516 objects with a detection of the H$\alpha$ emission line, that represent the star-forming population at this epoch having a stellar mass range of $10^{9.57}\le M_{\ast }/M_{\odot }\lesssim 10^{11.4}$ and a star formation rate range of $15\lesssim \mathrm{SFR}/(M_{\odot }\mathrm{y}{\mathrm{r}}^{-1})\lesssim 600$. We measure the projected two-point correlation function while carefully taking into account observational biases, and find a significant clustering amplitude at scales of $0.04$-$10h^{-1}\mathrm{cMpc}$, with a correlation length $r_0=5.21_{-0.67}^{+0.70}{h}^{-1}\mathrm{cMpc}$ and a bias $b=2.59_{-0.34}^{+0.41}$. We interpret our clustering measurement using a halo occupation distribution model. The sample galaxies appear to reside in halos with mass $M_{\mathrm{h}}=4.6_{-1.6}^{+1.1}\times 10^{12}{h}^{-1}{M}_{\odot }$ on average that will likely become present-day halos of mass $M_{\mathrm{h}}(z=0)\sim 2\times 10^{13}{h}^{-1}{M}_{\odot }$, equivalent to the typical halo mass scale of galaxy groups. We then confirm the decline of the stellar-to-halo mass ratio at $M_{\mathrm{h}}<10^{12}{M}_{\odot }$, finding $M_{\ast }/M_{\mathrm{h}}\approx 5\times 10^{-3}$ at $M_{\mathrm{h}}=10^{11.86}{M}_{\odot }$, which is lower by a factor of 2-4 than those measured at higher masses. 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 $z>1$.

28 pages, 26 figures, submitted to ApJ