A Search For Failed Supernovae and Other Observational Constraints on the Supernova Mechanism

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Astronomers know that all massive stars (stars more than eight times the mass of our Sun) must collapse when their cores become mostly iron and they can no longer generate energy through nuclear fusion. In most cases, this collapse leads to a supernova (SN) explosion, but it is believed that some stars collapse directly to a black hole without exploding, an outcome known as a "failed supernova." A research group at the Ohio State University will use a multifaceted observational and theoretical approach to better understand the fates of massive stars and the formation of black holes. To do this, they will use the twin 8.4-meter Large Binocular Telescope (LBT) to monitor all of the massive, mature stars in 27 nearby star-forming galaxies. This will allow them to confirm the first candidate failed supernova, measure the properties of SN progenitors, and explore the boundary between the faintest SNe and stellar outbursts. While doing so, the project will advance the training of students and broaden the public's understanding and interest in the science of stars and their complicated roads to death.Searches for the progenitors of SNe are finding a deficit of high mass progenitors. This deficit can be explained if about 20% of core collapses fail and produce a black hole without a SN explosion. This failed SN fraction also naturally explains the compact object mass function. Very few SN progenitors are well characterized, making it difficult to determine the mapping between progenitors and outcomes. The Ohio State program will yield roughly one well-characterized progenitor each year. It will also pioneer the study of low-level progenitor variability, as a balance to SN searches that are detecting small numbers of bright outbursts shortly before SN explosions. This project will also explore the late time properties and evolution of mysterious, low luminosity, SN-like objects, and may validate modern theoretical surveys of core collapse outcomes that suggest weak SN occur in several different mass ranges.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.