From Luminescence to Enigma: The Birth of Black Holes
Kyoto University
Kyoto, Japan -- The conventional understanding of how black holes come into existence has often mirrored the very nature of these cosmic phenomena: shrouded in darkness, enigmatic, and surprisingly silent, despite their immense gravitational pull and impact on the universe. Typically, stellar-mass black holes emerge from the dramatic final collapse of massive stars that are at least thirty times more massive than our Sun. Unlike their less massive counterparts, these colossal stars do not culminate in brilliant supernovae.
However, this perspective has been challenged by the groundbreaking observations made by a team of researchers at Kyoto University regarding a specific event known as SN 2022esa.
The researchers had previously speculated about whether all massive stars—those with a mass exceeding thirty times that of the Sun—perish quietly without producing supernovae or if some indeed explode in a spectacular and energetic manner. Their investigations led to the identification of a type Ic-CSM supernova, which appeared to originate from a Wolf-Rayet star. These stars are so extraordinarily massive and radiant that scientists believe they serve as the precursors to black hole formation.
To delve deeper into the characteristics of this unusual supernova, the research team employed both the Seimei telescope in Okayama and the Subaru telescope in Hawaii. Through their observations, they successfully classified SN 2022esa as an Ic-CSM type supernova, revealing that the emergence of a black hole does not have to be a silent event; this explosion was detectable through electromagnetic signals.
Additionally, the researchers uncovered a fascinating aspect of the supernova's behavior: it exhibited a stable light-curve evolution over approximately one month. This pattern led them to theorize that the progenitor star underwent regular eruptions once a year leading up to the supernova explosion. Such periodic behavior strongly suggests that the progenitor was part of a binary system, likely involving a Wolf-Rayet star paired with another massive star, or even a black hole. They concluded that the fate of this stellar duo would be the creation of a black hole binary.
"Understanding the destinies of massive stars, including the formation of black holes or black hole binaries, raises crucial questions within the field of astronomy," stated Keiichi Maeda, the lead author of the study. "Our research opens up new avenues for comprehending the evolutionary journey of massive stars towards becoming black hole binaries."
This study also highlights the advantages of utilizing two telescopes with distinct observational capabilities. The combination of Seimei's agility and responsiveness alongside Subaru's heightened sensitivity proved to be an effective strategy for capturing this significant phenomenon. The team is enthusiastic about continuing their research with both telescopes in the future.
"We anticipate uncovering many intriguing insights regarding astronomical transients and explosive events such as supernovae," added Maeda.
