Depletion timescale as a function of redshift for our sample. We compare the depletion timescale of our sample (blue diamonds and red squares) along with the SMGs (grey circles) from Carilli et al. (2010), Walter et al. (2012), Ivison et al. (2013), Fu et al. (2012, 2013), Alaghband-Zadeh et al. (2013). The blue diamonds represent the depletion timescales corresponding to gas mass calculated using α_CO = 3.4 and the red squares are computed using α_CO = 0.8. The main sequence in the grey shaded region follows the relation presented in Saintonge et al. (2013), with α values ranging from −1.5 (Davé et al. 2012) to −1.0 (Magnelli et al. 2013).