Mergers of two carbon–oxygen ( CO ) WDs have been considered as progenitors of Type Ia supernovae ( SNe Ia ) .
Based on smoothed particle hydrodynamics ( SPH ) simulations , previous studies claimed that mergers of CO WDs lead to an SN Ia explosion either in the dynamical merger phase or stationary rotating merger remnant phase .
However , the mass range of CO WDs that lead to an SN Ia has not been clearly identified yet .
In the present work , we perform systematic SPH merger simulations for the WD masses ranging from 0.5 ~ { } M _ { \odot } to 1.1 ~ { } M _ { \odot } with higher resolutions than the previous systematic surveys and examine whether or not carbon burning occurs dynamically or quiescently in each phase .
We further study the possibility of SN Ia explosion and estimate the mass range of CO WDs that lead to an SN Ia .
We found that when the both WDs are massive , i.e. , in the mass range of 0.9 ~ { } M _ { \odot } { \leq } M _ { 1 , 2 } { \leq } 1.1 ~ { } M _ { \odot } , they can explode as an SN Ia in the merger phase .
On the other hand , when the more massive WD is in the range of 0.7 ~ { } M _ { \odot } { \leq } M _ { 1 } { \leq } 0.9 ~ { } M _ { \odot } and the total mass exceeds 1.38 ~ { } M _ { \odot } , they can finally explode in the stationary rotating merger remnant phase .
We estimate the contribution of CO WD mergers to the entire SN Ia rate in our galaxy to be of { \raisebox { -2.15 pt } { $\ > \stackrel { \textstyle < } { \sim } \ > $ } } 9 \% .
So , it might be difficult to explain all galactic SNe Ia by CO WD mergers .