Top: ALMA spectrum of the [C ii] detections, extracted from the an elliptical aperture of size 0.55′′ × 1.03′′ with resolution of 40 km s^-1. The blue solid line is the spectrum by Maiolino et al. (2015), while the orange and green lines show the spectrum and noise level obtained from the new high-resolution observations, respectively. Bottom: high-resolution ALMA map (angular-resolution = 0.3′′ × 0.2′′) obtained by integrating the line under the gold shaded region in the top panel of Fig. 2a (i.e. −70 < v < 10 km s^-1). Black contours are at levels of –2, –1, 1, and 2 times the noise per beam in the same map, i.e. 9 mJy/beam km s^-1.