Direct Evidence for an Early Reionization of the Universe?

We examine the possible reionization of the intergalactic medium by the source UDF 033238.7274839.8 (hereafter HUDF-JD2), which was discovered in deep HST/VLT/Spitzer images obtained as part of the Great Observatories Origins Deep Survey and Hubble Ultra Deep Field projects. Mobasher et al. have identified HUDF-JD2 as a massive (~6 * 10^11 M(circle dot operator)) post-starburst galaxy at redshift z >~6.5. We find that HUDF-JD2 may be capable of reionizing its surrounding region of the universe, starting the process at a redshift as high as z ~~15 +- 5.