Formation of Close Double White Dwarfs model results

Formation of Close Double White Dwarfs: model results VS observation Huaju LI, Xuefei Chen, Hongwei GE and Zhanwen HAN Yunnan Astronomical Observatories, Chinese Academy of Sciences, Kunming 650011, China lihuaju@ynao. ac. cn We do a binary population synthesis (BPS) simulation about the close double white dwarfs (CDWDs), two main BPS modifications are as follows. 1. The mass–orbital period relation after stable RLOF is implemented into our BPS code; 2. The mass transfer stability criterion is obtained from adiabatic mass loss model (Ge, H et al. 2015). CE+CE Stable RLOF+CE Figure 3. Orbital periods distribution of CDWDs from different channels and different types. Vertical lines represent the orbital periods of 37 observed samples. Figure 1. The distribution of masses of CDWDs. m 1 and m 2 represent the brighter and dimmer component, respectively. Solid circles are 19 observed samples. Figure 4. Mass ratio (m 1/m 2) distribution of CDWDs from different channels and different types. Important tip: Although more than 100 CDWDs have been observed, at least half of them are of extremely low-mass survey (ELMS). In Fig. 1 -4, we rule out the observed samples from ELMS and those with component mass < 0. 2 solar mass. The first reason is that if we consider samples from ELMS, there should be a strong selective effect. The second reason is that our BPS code still have some difficulties in reproducing low mass white dwarfs and Li (2019) has already done a good job in reproducing low mass white dwarfs. Figure 2. The distribution of orbital periods vs m 1 of CDWDs. Solid circles and triangles are 37 observed samples. Solid circles are corresponding to those in Fig 1. , while solid triangles represent those have minimum masses for m 2. References (among others) : Chen, X. , Han, Z. , Deca, J. , Podsiadlowski, P. 2013, MNRAS, 434, 186 Ge, H. , Webbink, R. F. , Chen, X. , Han, Z. 2015, APJ, 812, 40 Han, Z. 1998, MNRAS, 296, 1019 Li, Z. , Chen, X. , Chen, H. L. , Han, Z. 2019, APJ, 871, 148