Andrea Comastri

TL;DR: In this article, the authors present multi-wavelength observations (from optical to sub-millimeter, including Spitzer and SCUBA) of H2XMMJ 003357.

TL;DR: In this article, the authors reported the discovery of the first heavily obscured QSO candidate in the early universe, hosted by a close (≈5 kpc) galaxy pair at z ǫ = 6.515.

TL;DR: In this article, Chandra observations of 10 $z>6$ QSOs, selected to have virial black-hole mass estimates from Mg II line spectroscopy, were used to investigate the X-ray properties of the QSO population in the first Gyr of the Universe, focusing in particular on the $L_{UV}-L_{X}$ relation, which is traced by the $\alpha_{ox}$ parameter, and the shape of their Xray spectra.

TL;DR: In this article, a 14 ks XMM-Newton observation of the hyperluminous infrared galaxy IRAS 09104+4109, which harbors a type 2 quasar in its nucleus, was used to study the properties of absorbing matter and the Fe K complex at 6-7 keV in this source.

TL;DR: The BeppoSAX observations of the bright Narrow-line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5m telescope at La Silla.