A brief Chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326 showed it to be a relatively bright, soft X-ray source with a count rate of about 1 count ks(-1). In this article, we present results for the quasar from a 65-ks XMM-Newton observation, which constrains its spectral shape well. The quasar is clearly detected with a total of similar to 460 net counts in the 0.2-10 keV band. The spectrum is characterized by a simple power-law model with a photon index of Gamma = 2.30(-0.10)(+0.10) and the intrinsic 2-10 keV luminosity is 3.14 x 10(45) erg s(-1). The 1 sigma upper limit to any intrinsic absorption column density is N-H = 6.07 x 10(22) cm(-2). No significant iron emission lines were detected. We derive an X-ray-to- optical flux ratio alpha(ox) of -1.74 +/- 0.01, consistent with the values found in other quasars of comparable ultraviolet luminosity. We did not detect significant flux variations either in the XMM-Newton exposure or between XMM-Newton and Chandra observations, which are separated by similar to 8 months. The X-ray observation enables the bolometric luminosity to be calculated after modelling the spectral energy distribution: the accretion rate is found to be sub-Eddington.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/625470 |
| Date | 09 1900 |
| Creators | Ai, Yanli, Fabian, A. C., Fan, Xiaohui, Walker, S. A., Ghisellini, G., Sbarrato, T., Dou, Liming, Wang, Feige, Wu, Xue-Bing, Feng, Longlong |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | OXFORD UNIV PRESS |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. |
| Relation | https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx1231 |
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