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AN ARCHIVAL Chandra AND XMM-Newton SURVEY OF TYPE 2 QUASARS.
- Source :
-
Astrophysical Journal . 11/1/2013, Vol. 777 Issue 1, p27-43. 17p. - Publication Year :
- 2013
-
Abstract
- In order to investigate obscuration in high-luminosity type 2 active galactic nuclei (AGNs), we analyzed Chandra and XMM-Newton archival observations for 71 type 2 quasars detected at 0.05 < z < 0.73, which were selected based on their [O III] λ5007 emission lines. For 54 objects with good spectral fits, the observed hard X-ray luminosity ranges from 2 × 1041 to 5.3 × 1044 erg s–1, with a median of 1.1 × 1043 erg s–1. We find that the means of the column density and photon index of our sample are log NH = 22.9 cm–2 and Γ = 1.87, respectively. From simulations using a more physically realistic model, we find that the absorbing column density estimates based on simple power-law models significantly underestimate the actual absorption in approximately half of the sources. Eleven sources show a prominent Fe Kα emission line (EW>100 eV in the rest frame) and we detect this line in the other sources through a joint fit (spectral stacking). The correlation between the Fe Kα and [O III] fluxes and the inverse correlation of the equivalent width of the Fe Kα line with the ratio of hard X-ray and [O III] fluxes is consistent with previous results for lower luminosity Seyfert 2 galaxies. We conclude that obscuration is the cause of the weak hard X-ray emission rather than intrinsically low X-ray luminosities. We find that about half of the population of optically selected type 2 quasars are likely to be Compton thick. We also find no evidence that the amount of X-ray obscuration depends on the AGN luminosity (over a range of more than three orders of magnitude in luminosity). [ABSTRACT FROM AUTHOR]
- Subjects :
- *GALACTIC nuclei
*QUASARS
*STELLAR luminosity function
*X-ray astronomy
Subjects
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 777
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 94288659
- Full Text :
- https://doi.org/10.1088/0004-637X/777/1/27