Type IIn Supernova Detections in z ~ 2 Lyman Break Galaxies: Probing the IMF Directly

Abstract

Type IIn supernovae (SNe IIn) exhibit luminous ultraviolet continua during outburst and luminous, long-lived narrow ultraviolet and optical emission lines attributed to circumstellar interaction. These properties have enabled successful detections at z ~ 2 in archival imaging and continued investigations from late-time spectroscopy. Because SNe IIn are believed to have massive (≳50M_☉) progenitors, searches in the well-studied Lyman break galaxy (LBG) host population offer the prospect of testing the form of the high-redshift stellar initial mass function (IMF) in a high density star formation environment directly. I briefly discuss our z ~ 2 photometric detection method targeting LBGs in the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) and present data from the first 6 confirmed z ~ 2 SNe IIn pulled from 30 photometric SN candidates. A comparison of the color and magnitude distributions of the SN host galaxies to that of the full LBG sample finds that z ~ 2 SNe preferentially occur in bluer, fainter galaxies. I conclude with a discussion of an approach that uses the CFHTLS pilot sample to provide a first estimate of the form of the high-redshift IMF. Upcoming deep synoptic imaging surveys will greatly improve z ~ 2 SNe IIn statistics from ~10^5 expected detections and future large aperture space- and ground-based telescopes will have the sensitivities to extend this work to z ≳ 6.