Gemini/GMOS Spectroscopy of Globular Clusters in the Merger Remnant Galaxy M85

M85 is a peculiar S0 galaxy in Virgo and is a well-known merger remnant. In this paper, we present the first spectroscopic study of globular clusters(GCs) in M85. We obtain spectra for 21 GC candidates and the nucleus of M85 using the Gemini Multi-Object Spectrograph on the Gemini North 8.1 m telescope. From their radial velocities, 20 of the GCs are found to be members of M85. We find a strong rotation signal of the M85 GC system with a rotation amplitude of 235 km s$^{-1}$. The rotation axis of the GC system has a position angleof about 161$^{\circ}$, which is 51$\rlap{.}{^\circ}$5 larger than that of the stellar light. The rotation-corrected radial velocitydispersion of the GC system is estimated to be $\sigma_{\rm r,cor} = $ 160 km s$^{-1}$. The rotation parameter $\Omega R_{\rm icor}/\sigma_{\rm r,cor}$ of the GC system is derived to be 1.47$^{+1.05}_{-0.48}$, which is one of the largest among known early-type galaxies. The ages and metallicities of the GCs, which show the same trend as the results based on Lickindices, are derived from full spectrum fitting (ULySS). About a half of the GCs are an intermediate-age population of which the mean age is $\sim$ 3.7 $\pm$ 1.9 Gyr, having a mean [Fe/H] value of --0.26. The other half are old and metal-poor. These results suggest that M85 experienced a wet merging event about 4 Gyr ago, forming a significant population of star clusters. The strong rotational feature of the GC system can be explained by an off-center major merging.