Kinematics of Mg II absorbers from the redshift-space distortion around massive quiescent galaxies

The kinematics of Mg II absorbers is the key to understanding the origin of cool, metal-enriched gas clouds in the circumgalactic medium of massive quiescent galaxies. Exploiting the fact that the cloud line-of-sight velocity distribution is the only unknown for predicting the redshift-space distortion (RSD) of Mg II absorbers from their 3D real-space distribution around galaxies, we develop a novel method to infer the cool cloud kinematics from the redshift-space galaxy-cloud cross-correlation xi(s). We measure xi(s) for similar to 10(4) Mgii absorbers around similar to 8 x 10(5) CMASS galaxies at 0.4 < z < 0.8. We discover that xi(s) does not exhibit a strong Fingers-of-God effect, but is heavily truncated at velocity similar to 300 km s(-1) . We reconstruct both the redshift and real-space cloud number density distributions inside haloes, xi(s)(1h) and xi(1h), respectively. Thus, for any model of cloud kinematics, we can predict xi(s)(1h) from the reconstructed xi(1h), and self-consistently compare to the observed xi(s)(1h). We consider four types of cloud kinematics, including an isothermal model with a single velocity dispersion, a satellite infall model in which cool clouds reside in the subhaloes, a cloud accretion model in which clouds follow the cosmic gas accretion, and a tired wind model in which clouds originate from the galactic wind-driven bubbles. All the four models provide statistically good fits to the RSD data, but only the tired wind model can reproduce the observed truncation by propagating ancient wind bubbles at similar to 250 km s(-1) on scales similar to 400 h(-1) kpc. Our method provides an exciting path to decoding the dynamical origin of metal absorbers from the RSD measurements with upcoming spectroscopic surveys.