Jianfei Tang et al., Purple Mountain Observatory, Chinese Academy of Sciences, have investigated the effects of temperature anisotropy on the maser instability driven by the lower energy cutoff behavior. The results show that the lower energy cutoff behavior of energetic electrons can effectively excite maser instability and mild temperature anisotropy has significant effects on maser emission.

The most important conclusion is that the mild temperature anisotropy has significant effects onthe maser instability. In both cases of and ,this moderate anisotropy with lower energy cutoff behavior canexcite maser instability effectively. It clearly shows that thegrowth rates increase with the perpendicular velocity spread  and parallel velocity spread . There is a critical valuefor  and . The growth rates increase rapidly when thevelocity spreads are less than the critical value and the growthrates are insensitive to the velocity spreads when they are large enough.