Journal article
Gemini Near Infrared Spectrograph–Distant Quasar Survey: The Chandra View
The Astrophysical journal, v 991(1), 91
01 Sep 2025
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Abstract
We present Chandra observations of 63 sources from the Gemini Near Infrared Spectrograph−Distant Quasar Survey, of which 54 were targeted by snapshot observations in Cycle 24. A total of 55 sources are clearly detected in at least one X-ray band, and we set stringent upper limits on the X-ray fluxes of the remaining eight sources. In combination with rest-frame ultraviolet–optical spectroscopic data for these sources, we assess whether X-rays can provide a robust accretion rate indicator for quasars, particularly at the highest accessible redshifts. We utilize a recently modified Hβ-based Eddington luminosity ratio estimator, as well as the C iv λ1549 emission-line parameter space, to investigate trends and correlations with the optical–X-ray spectral slope (αox) and the effective hard X-ray power-law photon index (Γ). We find that αox does not improve current accretion rate estimates based on Hβ or C iv. Instead, within the limitations of our sample, we confirm previous findings that the C iv parameter space may be a better indicator of the accretion rate up to z ∼ 3.5. We also find that the average Γ values for a small subset of our sources, as well as the average Γ value in different groupings of our sources, are consistent with their respective relatively high Eddington luminosity ratios. Deeper X-ray observations of our X-ray-detected sources are needed for measuring Γ accurately and testing whether this parameter can serve as a robust, unbiased accretion rate diagnostic.
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Details
- Title
- Gemini Near Infrared Spectrograph–Distant Quasar Survey: The Chandra View
- Creators
- Andrea MarlarOhad ShemmerMichael BrothertonGordon RichardsDix CooperBrandon MatthewsW BrandtR Plotkin
- Publication Details
- The Astrophysical journal, v 991(1), 91
- Publisher
- IOP Publishing
- Number of pages
- 18
- Grant note
- SI divided by Smithsonian Astrophysical Observatory (SAO)https://doi.org/10.13039/100009207: GO3-24089X, NAS8-03060 National Aeronautics and Space Administration (NASA) through Chandra award: 80NSSC24K1468 NASAPenn State Eberly EndowmentNational Aeronautics and Space Administration
The scientific results presented in this paper are based on observations made by the Chandra X-Ray Observatory and on data obtained from the Chandra Data Archive. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Chandra award No. GO3-24089X (A.M., O.S.) issued by the Chandra X-Ray Observatory Center (CXC), which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. Support for this work was also provided by NASA under award No. 80NSSC24K1468 (O.S., G.T.R). W.N.B. acknowledges support from the Penn State Eberly Endowment. We thank an anonymous referee for providing valuable feedback that helped to improve this manuscript. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration, as well as NASA's Astrophysics Data System Bibliographic Services.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:001572896000001
- Other Identifier
- 991022097939204721