The White Dwarf Mass Distributions of PCEB with Different αCE Values

We report the preliminary results of our population synthesis study for post common-envelope binaries (PCEBs) with a detailed evolutionary process using the STARS code. We concentrate our effort in reproducing the white dwarf mass distribution, and comparing it with the recent observational data from the Sloan Digital Sky Survey Data Release 7 for WDMS binaries. We employ the Monte Carlo method to choose the initial parameters of the progenitors (primary mass, mass ratio and orbital period), then we follow the evolution from the zero age main sequence to the end of the common-envelope phase. We include approximate post-Helium flash evolution for primary masses less than 2.0 M_⊙. We study the effect of using different common envelope ejection efficiency values on the white dwarf mass distribution. In particular, we adopt constant α_CE values of 0.25, 0.50, and 0.75. The distributions resulting from our population synthesis show a double-peak profile, except for the smallest α_CE value. We find that smaller efficiency values significantly affect the post-CE systems with low-mass white dwarf.