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Pair-instability and pulsational pair-instability supernovae (PPISN) have not been unambiguously observed so far. They are, however, promising candidates for the progenitors of the heaviest binary black hole (BBH) mergers detected. If these BBHs are the product of binary evolution, then PPISNe could occur in very close binaries. Motivated by this, we discuss the implications of a PPISN happening with a close binary companion, and what impact these events have on the formation of merging BBHs through binary evolution. For this, we have computed a set of models of metal-poor ($Z_odot/10$) single helium stars using the texttt{MESA} software instrument. For PPISN progenitors with pre-pulse masses $>50M_odot$ we find that, after a pulse, heat deposited throughout the layers of the star that remain bound cause it to expand to more than $100R_odot$ for periods of $10^2-10^4;$~yrs depending on the mass of the progenitor. This results in long-lived phases of Roche-lobe overflow or even common-envelope events if there is a close binary companion, leading to additional electromagnetic transients associated to PPISN eruptions. If we ignore the effect of these interactions, we find that mass loss from PPISNe reduces the final black hole spin by $sim 30%$, induces eccentricities below the threshold of detectability of the LISA observatory, and can produce a double-peaked distribution of measured chirp masses in BBH mergers observed by ground-based detectors.
We calculate the evolution of massive stars, which undergo pulsational pair-instability (PPI) when the O-rich core is formed. The evolution from the main-sequence through the onset of PPI is calculated for stars with the initial masses of $80 - 140$
Massive stars that end their lives with helium cores in the range of 35 to 65 Msun are known to produce repeated thermonuclear outbursts due to a recurring pair-instability. In some of these events, solar masses of material are ejected in repeated ou
In certain mass ranges, massive stars can undergo a violent pulsation triggered by the electron/positron pair instability that ejects matter, but does not totally disrupt the star. After one or more of these pulsations, such stars are expected to und
Massive stars of helium cores of 35-65 Msun eventually encounter the electron/positron creation instability, and it triggers explosive carbon or oxygen burning that produces several thermonuclear eruptions. The resulting catastrophe collisions of eru
Numerical studies of primordial star formation suggest that the first stars in the universe may have been very massive. Stellar models indicate that non-rotating Population III stars with initial masses of 140-260 Msun die as highly energetic pair-in