http://arxiv.org/abs/2001.06020
By comparing the properties of Red Supergiant (RSG) supernova progenitors to those of field RSGs, it has been claimed that there is an absence of progenitors with luminosities $L$ above $\log(L/L_\odot) > 5.2$. This is in tension with the empirical upper luminosity limit of RSGs at $\log(L/L_\odot) = 5.5$, a result known as the `Red Supergiant Problem’. This has been interpreted as evidence for an upper mass threshold for the formation of black-holes. In this paper, we compare the observed luminosities of RSG SN progenitors with the observed RSG $L$-distribution in the Magellanic Clouds. Our results indicate that the absence of bright SN II-P/L progenitors in the current sample can be explained at least in part by the steepness of the $L$-distribution and a small sample size, and that the statistical significance of the Red Supergiant Problem is between 1-2$\sigma$ . Secondly, we model the luminosity distribution of II-P/L progenitors as a simple power-law with an upper and lower cutoff, and find an upper luminosity limit of $\log(L_{\rm hi}/L_\odot) = 5.20^{+0.17}{-0.11}$ (68\% confidence), though this increases to $\sim$5.3 if one fixes the power-law slope to be that expected from theoretical arguments. Again, the results point to the significance of the RSG Problem being within $\sim 2 \sigma$. Under the assumption that all progenitors are the result of single-star evolution, this corresponds to an upper mass limit for the parent distribution of $M{\rm hi} = 19.2{\rm M_\odot}$, $\pm1.3 {\rm M_\odot (systematic)}$, $^{+4.5}{-2.3} {\rm M\odot}$ (random) (68\% confidence limits).
B. Davies and E. Beasor
Mon, 20 Jan 20
5/60
Comments: 9 pages, 7 figures, accepted for publication in MNRAS