Author/Authors :
Cutri، R. M. نويسنده , , D. C. Hines، نويسنده , , K. Pounds، نويسنده , , B. J. Wilkes، نويسنده , , G. D. Schmidt، نويسنده , , P. S. Smith، نويسنده , , H. Ghosh، نويسنده , , B. Nelson، نويسنده ,
Abstract :
XMM-Newton spectra of five red 2MASS active galactic nuclei (AGNs), selected from a sample observed by Chandra to be relatively X-ray bright and to cover a range of hardness ratios, confirm the presence of substantial absorbing material in three sources with optical classifications ranging from type 1 to type 2. A flat (hard) power-law continuum is observed in the other two. The combination of X-ray absorption and broad optical emission lines suggests either a small (nuclear) absorber or a favored viewing angle so as to cover the X-ray source but not the broad emission-line region (BELR). A soft excess is detected in all three type 1 sources. We speculate that this may arise in an extended region of ionized gas, perhaps linked to the polarized (scattered) optical light present in these sources. The spectral complexity revealed by XMM-Newton emphasizes the limitations of the low-S/N Chandra data. The new results strengthen our earlier conclusions that the observed X-ray continua of red AGNs are unusually hard at energies >2 keV. Their observed spectra are consistent with contributing significantly to the missing hard or absorbed population of the cosmic X-ray background (CXRB), although their intrinsic power-law slopes are typical of broad-line (type 1) AGNs ((gamma) ~1.7-1.9). This suggests that the missing X-rayabsorbed CXRB population may include type 1 AGNs or QSOs in addition to the type 2 AGNs generally assumed.