Progenitor’s rotation has a crucial impact on the mass of black holes

New paper on the “Impact of progenitor’s rotation and compactness on the mass of black holes” by Mapelli et al. accepted for publication in the Astrophysical Journal.


We investigate the impact of stellar rotation on the formation of black holes (BHs), by means of our population-synthesis code SEVN. Rotation affects the mass function of BHs in several ways. In massive metal-poor stars, fast rotation reduces the minimum zero-age main sequence (ZAMS) mass for a star to undergo pair instability and pulsational pair instability. Moreover, stellar winds are enhanced by rotation, peeling-off the entire hydrogen envelope. As a consequence of these two effects, the maximum BH mass we expect from the collapse a rotating metal-poor star is only 45 M, while the maximum mass of a BH born from a non-rotating star is 60 M. Furthermore, stellar rotation reduces the minimum ZAMS mass for a star to collapse into a BH from 18−25 M to 13−18 M. Finally, we have investigated the impact of different core-collapse supernova (CCSN) prescriptions on our results. While the threshold value of compactness for direct collapse and the fallback efficiency strongly affect the minimum ZAMS mass for a star to collapse into a BH, the fraction of hydrogen envelope that can be accreted onto the final BH is the most important ingredient to determine the maximum BH mass. Our results confirm that the interplay between stellar rotation, CCSNe and pair instability plays a major role in shaping the BH mass spectrum.

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agggiungere la figura news/SEVN_00003_comp03_allf.png

Didascalia della figura: Predicted mass of the compact object as a function of the ZAMS mass of the progenitor star at metallicity Z=0.0003 for fast rotating stars (red and black lines) and non-rotating stars (blue and green lines). We consider different core-collapse supernova prescriptions, as detailed in the new paper