The X-ray Properties of the Most-Luminous Quasars from the Sloan Digital Sky Survey

Understand

Utilizing 21 new Chandra observations as well as archival Chandra, ROSAT, and XMM-Newton data, we study the X-ray properties of a representative sample of 59 of the most optically luminous quasars in the Universe (M_i~~-29.3 to -30.2) spanning a redshift range of z~~1.5-4.5.

• Our full sample consists of 32 quasars from the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3) quasar catalog, two additional objects in the DR3 area that were missed by the SDSS selection criteria, and 25 comparably luminous quasars at z>~4.
• This is the largest X-ray study of such luminous quasars to date.
• By jointly fitting the X-ray spectra of our sample quasars, excluding radio-loud and broad absorption line (BAL) objects, we find a mean X-ray power-law photon index of Gamma=1.92^{+0.09}_{-0.08} and constrain any neutral intrinsic absorbing material to have a mean column density of N_H<~2x10^{21} cm^{-2}.