Detecting z > 2 Type IIn Supernovae^*

Type IIn supernovae (SNe IIn) dominate the brightest supernova events in observed FUV flux (~1200-2000 Å). We show that multiband, multiepoch optical surveys complete to m_r = 27 can detect the FUV emission of ~25 z > 2 SNe IIn deg⁻² yr⁻¹ (rest frame, or ~10 SNe IIn deg⁻² yr⁻¹ observed frame) to 4 σ using a technique that monitors color-selected galaxies. Moreover, the strength and evolution of the bright emission lines observed in low-redshift SNe IIn imply that the Lyα emission features in ~70% of z > 2 SNe IIn are above the spectroscopic thresholds of 8 m class telescopes for ~2 yr (rest frame). As a result, existing facilities have the capability to both photometrically detect and spectroscopically confirm z > 2 SNe IIn and pave the way for efficient searches by future 8 m class survey and 30 m class telescopes. The method presented here uses the sensitivities and wide-field capabilities of current optical instruments and exploits (1) the efficiency of z > 2 galaxy color selection techniques, (2) the intrinsic brightness distribution (⟨ M_B⟩ = − 19.0,σ ± 0.9) and blue profile of SN IIn continua, (3) the presence of extremely bright, long-lived emission features, and (4) the potential to detect blueshifted SN Lyα emission shortward of host galaxy Lyα features.