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The X-ray and mid-infrared luminosities in luminous type 1 quasars

Chen(陳建廷), Chien-Ting J.; Hickox, Ryan C.; Goulding, Andrew D.; Stern, Daniel; Assef, Roberto; Kochanek, Christopher S.; Brown, Michael J.I.; Harrison, Chris M.; Hainline, Kevin N.; Alberts, Stacey; Alexander, David M.; Brodwin, Mark; Moro, Agnese Del; Forman, William R.; Gorjian, Varoujan; Jones, Christine; Murray, Stephen S.; Pope, Alexandra; Rovilos, Emmanouel

The X-ray and mid-infrared luminosities in luminous type 1 quasars Thumbnail


Chien-Ting J. Chen(陳建廷)

Ryan C. Hickox

Andrew D. Goulding

Daniel Stern

Roberto Assef

Christopher S. Kochanek

Michael J.I. Brown

Chris M. Harrison

Kevin N. Hainline

Stacey Alberts

Mark Brodwin

Agnese Del Moro

William R. Forman

Varoujan Gorjian

Christine Jones

Stephen S. Murray

Alexandra Pope

Emmanouel Rovilos


Several recent studies have reported different intrinsic correlations between the active galactic nucleus (AGN) mid-IR luminosity (${L}_{\mathrm{MIR}}$) and the rest-frame 2–10 keV luminosity (L X) for luminous quasars. To understand the origin of the difference in the observed ${L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}}$ relations, we study a sample of 3247 spectroscopically confirmed type 1 AGNs collected from Boötes, XMM-COSMOS, XMM-XXL-North, and the Sloan Digital Sky Survey quasars in the Swift/XRT footprint spanning over four orders of magnitude in luminosity. We carefully examine how different observational constraints impact the observed ${L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}}$ relations, including the inclusion of X-ray-nondetected objects, possible X-ray absorption in type 1 AGNs, X-ray flux limits, and star formation contamination. We find that the primary factor driving the different ${L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}}$ relations reported in the literature is the X-ray flux limits for different studies. When taking these effects into account, we find that the X-ray luminosity and mid-IR luminosity (measured at rest-frame $6\,\mu {\rm{m}}$, or ${L}_{6\mu {\rm{m}}}$) of our sample of type 1 AGNs follow a bilinear relation in the log–log plane: $\mathrm{log}{L}_{{\rm{X}}}=(0.84\pm 0.03)\times \mathrm{log}{L}_{6\mu {\rm{m}}}/{10}^{45}$ erg s−1 + (44.60 ± 0.01) for ${L}_{6\mu {\rm{m}}}\lt {10}^{44.79}$ erg s−1, and $\mathrm{log}{L}_{{\rm{X}}}=(0.40\pm 0.03)\times \mathrm{log}{L}_{6\mu {\rm{m}}}/{10}^{45}$ erg s−1 + (44.51 ± 0.01) for ${L}_{6\mu {\rm{m}}}\,\geqslant {10}^{44.79}$ erg s−1. This suggests that the luminous type 1 quasars have a shallower ${L}_{{\rm{X}}}\mbox{--}{L}_{6\mu {\rm{m}}}$ correlation than the approximately linear relations found in local Seyfert galaxies. This result is consistent with previous studies reporting a luminosity-dependent ${L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}}$ relation and implies that assuming a linear ${L}_{{\rm{X}}}\mbox{--}{L}_{6\mu {\rm{m}}}$ relation to infer the neutral gas column density for X-ray absorption might overestimate the column densities in luminous quasars.


Chen(陳建廷), C. J., Hickox, R. C., Goulding, A. D., Stern, D., Assef, R., Kochanek, C. S., …Rovilos, E. (2017). The X-ray and mid-infrared luminosities in luminous type 1 quasars. Astrophysical Journal, 837(2), Article 145.

Journal Article Type Article
Acceptance Date Jan 17, 2017
Online Publication Date Mar 13, 2017
Publication Date Mar 13, 2017
Deposit Date Jun 21, 2017
Publicly Available Date Jul 3, 2017
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 837
Issue 2
Article Number 145
Public URL


Published Journal Article (830 Kb)

Copyright Statement
© 2017. The American Astronomical Society. All rights reserved.

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