The addition of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) has led to a dramatic increase in our ability to study the z > 6 Universe. The increase in the near-infrared (NIR) sensitivity of WFC3 over previous instruments has enabled us to reach apparent magnitudes approaching 29 (AB). This allows us to probe the rest-frame ultraviolet (UV) continuum, redshifted into the NIR at z >6.
In this research the authors study the rest-UV luminosity function, and hence estimate the integrated star formation rate within 800Myr after Big Bang. Understanding the global star formation history at these redshifts is crucial in answering the question whether the UV photons produced by the short-lived OB stars were sufficient to reionize the Universe.
The studied leads to the conclusion that some reionization of the the primordial Universe seems to have been possible.
This paper was submitted to MNRAS on February 25th, 2010. (read more)