The End of the Dark Age: Probing the Dawn of First Light in the Universe

Theories of large scale structure formation, reionisation, and AGN evolution can be studied very well via Xray studies of highz QSOs, yet the Xray properties of z>4.5 QSOs are unknown. We propose observations of four QSOs: three ROSAT detected QSOs at 4.5 < z < 5.0, and the most distant known QSO at z6.28. We will use XMM data of a z6.28 QSO to gain crucial insights into the epoch of reionisation, and use the black hole properties to constrain different models predicting when structures first form. Together with Xray spectra of the 3 ROSAT QSOs, we will examine the evolution of AGN Xray spectra at high redshifts. Using extensive data already obtained at other wavelengths we will examine models for starburst and QSO triggering in AGN at highz. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]