THE X-RAY SPECTRUM OF THE z=6.30 QSO SDSS J1030+0524

We present a deep XMM-Newton observation of the z = 6.30 QSO SDSS J1030+0524, the second most distant quasar currently known. The data contain sufficient counts for spectral analysis, demonstrating the ability of XMM-Newton to measure X-ray spectral shapes of z similar to 6 QSOs with integration times greater than or similar to 100 ks. The X-ray spectrum is well fitted by a power law with index Gamma = 2.12 +/- 0.11, an optical-X-ray spectral slope of alpha(ox) = -1.80, and no absorption excess to the Galactic value, although our data are also consistent with a power-law index in the range 2.02 < Gamma < 2.5 and excess absorption in the range 0 < N-H (cm(-2)) < 8 x 10(22). There is also a H possible detection (similar to 2 sigma) of FeK alpha emission. The X-ray properties of this QSO are, overall, similar to those of lower redshift radio-quiet QSOs. This is consistent with the statement that the X-ray properties of radio-quiet QSOs show no evolution over 0 < z < 6.3. Combined with previous results, this QSO appears indistinguishable in any way from lower redshift QSOs, indicating that QSOs comparable to those seen locally existed less than 1 Gyr after the big bang.