Journal article
Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA
The Astrophysical journal, v 865(2)
26 Sep 2018
Abstract
We present XMM-Newton imaging spectroscopy of 10 weak emission-line quasars (WLQs) at , six of which are radio-quiet, and four that are radio-intermediate. The new X-ray data enabled us to measure the power-law photon index, at rest-frame energies >2 keV, in each source with relatively high accuracy. These measurements allowed us to confirm previous reports that WLQs have steeper X-ray spectra, suggesting higher accretion rates with respect to "typical" quasars. A comparison between the photon indices of our radio-quiet WLQs and those of a control sample of 85 sources shows that the first are significantly higher, at the 3 level. Collectively, the four radio-intermediate WLQs have lower photon indices with respect to the six radio-quiet WLQs, as may be expected if the spectra of the first group are contaminated by X-ray emission from a jet. Therefore, in the absence of significant jet emission along our line of sight, these results are in agreement with the idea that WLQs constitute the extreme high end of the accretion-rate distribution in quasars. We detect soft excess emission in our lowest-redshift radio-quiet WLQ, in agreement with previous findings suggesting that the prominence of this feature is associated with a high accretion rate. We have not detected signatures of Compton reflection, Fe K lines, or strong variability between two X-ray epochs in any of our WLQs, which can be attributed to their relatively high luminosity.
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Details
- Title
- Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA
- Creators
- Andrea Marlar - University of North TexasOhad Shemmer - University of North TexasS. F Anderson - University of WashingtonW. N Brandt - Pennsylvania State UniversityA. M Diamond-Stanic - Bates CollegeX Fan - Steward Health Care SystemB Luo - Nanjing UniversityR. M Plotkin - Curtin UniversityGordon T Richards - Drexel UniversityD. P Schneider - Pennsylvania State UniversityJianfeng Wu - Xiamen University
- Publication Details
- The Astrophysical journal, v 865(2)
- Publisher
- The American Astronomical Society
- Number of pages
- 14
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000445822300001
- Scopus ID
- 2-s2.0-85054849050
- Other Identifier
- 991019168752104721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics