Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars
© 2018. The American Astronomical Society. All rights reserved. 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-fra...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
| Published: |
Institute of Physics Publishing
2018
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| Online Access: | http://hdl.handle.net/20.500.11937/71238 |
| _version_ | 1848762427333672960 |
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| author | Marlar, A. Shemmer, O. Anderson, S. Brandt, W. Diamond-Stanic, A. Fan, X. Luo, B. Plotkin, Richard Richards, G. Schneider, D. Wu, J. |
| author_facet | Marlar, A. Shemmer, O. Anderson, S. Brandt, W. Diamond-Stanic, A. Fan, X. Luo, B. Plotkin, Richard Richards, G. Schneider, D. Wu, J. |
| author_sort | Marlar, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2018. The American Astronomical Society. All rights reserved. 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 3s 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 Ka lines, or strong variability between two X-ray epochs in any of our WLQs, which can be attributed to their relatively high luminosity. |
| first_indexed | 2025-11-14T10:47:24Z |
| format | Journal Article |
| id | curtin-20.500.11937-71238 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:47:24Z |
| publishDate | 2018 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-712382018-12-13T09:33:40Z Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars Marlar, A. Shemmer, O. Anderson, S. Brandt, W. Diamond-Stanic, A. Fan, X. Luo, B. Plotkin, Richard Richards, G. Schneider, D. Wu, J. © 2018. The American Astronomical Society. All rights reserved. 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 3s 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 Ka lines, or strong variability between two X-ray epochs in any of our WLQs, which can be attributed to their relatively high luminosity. 2018 Journal Article http://hdl.handle.net/20.500.11937/71238 10.3847/1538-4357/aad812 Institute of Physics Publishing restricted |
| spellingShingle | Marlar, A. Shemmer, O. Anderson, S. Brandt, W. Diamond-Stanic, A. Fan, X. Luo, B. Plotkin, Richard Richards, G. Schneider, D. Wu, J. Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title | Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title_full | Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title_fullStr | Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title_full_unstemmed | Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title_short | Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars |
| title_sort | steep hard-x-ray spectra indicate extremely high accretion rates in weak emission-line quasars |
| url | http://hdl.handle.net/20.500.11937/71238 |