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Chandra Observations of Red Sloan Digital Sky Survey Quasars
The Astronomical journal, v 132(5), pp 1977-1988
16 Jun 2006
Abstract
We present short \chandra observations of twelve bright (i<18) z_em~1.5 quasars from the Sloan Digital Sky Survey chosen to have significantly redder optical colors than most quasars at the same redshift. Of the five quasars with optical properties most consistent with dust reddening at the quasar redshift, four show indirect evidence of moderate X-ray absorption (inferred N_H~10^22 cm^-2) with a dust-to-gas ratio <1% of the SMC value. The remaining seven objects show no evidence for even moderate intrinsic X-ray absorption. Thus, while optically red quasars are marginally more likely to show signatures of X-ray absorption than optically selected quasars with normal colors, dust-reddened type 1 AGN (as opposed to fully obscured type 2 AGN) are unlikely to contribute significantly to the remaining unresolved hard X-ray background. The red quasar population includes objects with intrinsically red continua as well as objects with dust-reddened continua. Improved sample selection is thus needed to increase our understanding of either subpopulation. To identify dust-reddened quasars likely to exhibit X-ray absorption, some measure of spectral curvature is preferable to simple cuts in observed or relative broad-band colors.
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Details
- Title
- Chandra Observations of Red Sloan Digital Sky Survey Quasars
- Creators
- Patrick B HallS. C GallagherG. T RichardsD. M AlexanderS. F AndersonF BauerW. N BrandtD. P Schneider
- Publication Details
- The Astronomical journal, v 132(5), pp 1977-1988
- Grant note
- unidentified / Natural Sciences and Engineering Research Council of Canada (nserc_______::NSERC)
- Resource Type
- Other
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000241945500023
- Scopus ID
- 2-s2.0-33845934963
- Other Identifier
- 991014878371504721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics