Application of the binary population synthesis models to various astrophysical phenomena and objects

Studying stars is crucial for various reasons, and at least 50% of stars are in binaries.
I have extended the binary evolution code to the so-called binary population
synthesis code (BPS code), which applies the Monte Carlo methods to simulate various binary
systems. Especially, the code is featured by great flexibility, with which we can add new insights from
the stellar evolution theory and new observational indications in a strait forward way to provide new
predictions from the BPS theory. The latest version of my code includes a general scheme to treat different
assumptions in the mass transfer and common envelope processes, which allows us to clarify what are the most important
processes to determine the nature of binary systems under study. In this talk, I will introduce my recent 

two BPS works about formation of ultraluminous X-ray pulsar binaries and possible merger origins for supernovae.