2006AJ....131.1629S

The Hubble Ultra Deep Field Survey has provided the deepest optical and near-infrared views of the universe yet, and has enabled a search for the most distant supernovae, to z∼2.2. We have found four supernovae by searching spans of integrations of the Ultra Deep Field and the Ultra Deep Field Parallels taken with the Hubble Space Telescope paired with the Advanced Camera for Surveys and with NICMOS. Interestingly, none of these events were Type Ia supernovae (SNe Ia) above a redshift of 1.4, despite the substantially increased sensitivity per unit area to such objects over other surveys, including the Great Observatories Origins Deep Survey. However, we find that the low frequency of SNe Ia observed at 1.4<z<2.4 is statistically consistent with current estimates of the Type Ia supernova rate per unit volume, including the global star formation history combined with the nontrivial assembly time of SN Ia progenitors.