THE STELLAR ANCESTRY OF SUPERNOVAE IN THE MAGELLANIC CLOUDS. I. THE MOST RECENT SUPERNOVAE IN THE LARGE MAGELLANIC CLOUD

We use the star formation history (SFH) map of the Large Magellanic Cloud recently published by Harris and Zaritsky to study the sites of the eight smallest (and presumably youngest) supernova remnants (SNRs) in the Cloud: SN 1987A, N158A, N49, and N63A (core collapse remnants), 0509 - 67.5, 0519 - 69.0, N103B, and DEM L71 (Type Ia remnants). The local SFHs provide unique insights into the nature of the supernova (SN) progenitors, which we compare with the properties of the SN explosions derived from the remnants themselves and from SN light echoes. We find that all the core collapse SNe that we have studied are associated with vigorous star formation (SF) in the recent past. In the case of SN 1987A, the time of the last peak of SF (12 Myr) matches the lifetime of a star with the known mass of its blue supergiant progenitor (similar to 20 M-circle dot). More recent peaks of SF can lead to SNe with more massive progenitors, which opens the possibility of a Type Ib/c origin for SNRs N158A and N63A. Stars more massive than 21.5 M-circle dot are very scarce around SNR N49, implying that the magnetar SGR 0526 - 66 in this SNR was either formed elsewhere or came from a progenitor with a mass well below the 30 M-circle dot threshold suggested in the literature. Three of our four Ia SNRs are associated with old, metal-poor stellar populations. This includes SNR 0509 - 67.5, which is known to have been originated by an extremely bright Type Ia event, and yet is located very far away from any sites of recent SF, in a population with a mean age of 7.9 Gyr. The Type Ia SNR N103B, on the other hand, is associated with recent SF, and might have had a relatively younger and more massive progenitor with substantial mass loss before the explosion. We discuss these results in the context of our present understanding of core collapse and Type Ia SN progenitors.