Type II-P SN progenitor constraints

A maximum likelihood calculation suggests that the minimum stellar mass for a Type II-P to form is m_min_= 8.5^+1^_-1.5_M_{sun}_ and the maximum mass for II-P progenitors is m_max_= 16.5+/-1.5M_{sun}_, assuming a Salpeter initial mass function holds for the progenitor population (in the range {Gamma}=-1.35^+0.3^_-0.7_). The minimum mass is consistent with current estimates for the upper limit to white dwarf progenitor masses, but the maximum mass does not appear consistent with massive star populations in Local Group galaxies.

Red supergiants in the Local Group have masses up to 25M_{sun}_ and the minimum mass to produce a Wolf-Rayet star in single star evolution (between solar and LMC metallicity) is similarly 25-30M_{sun}_. The reason we have not detected any high-mass red supergiant progenitors above 17M_{sun}_ is unclear, but we estimate that it is statistically significant at 2.4{sigma} confidence. Two simple reasons for this could be that we have systematically underestimated the progenitor masses due to dust extinction or that stars between 17-25M_{sun}_produce other kinds of SNe which are not II-P. We discuss these possibilities and find that neither provides a satisfactory solution.

We term this discrepancy the 'red supergiant problem' and speculate that these stars could have core masses high enough to form black holes and SNe which are too faint to have been detected. We compare the ^56^Ni masses ejected in the SNe to the progenitor mass estimates and find that low-luminosity SNe with low ^56^Ni production are most likely to arise from explosions of low-mass progenitors near the mass threshold that can produce a core-collapse.