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Published June 1, 2015 | Published + Submitted
Journal Article Open

Broad Iron Emission from Gravitationally Lensed Quasars Observed by Chandra


Recent work has demonstrated the potential of gravitationally lensed quasars to extend measurements of black hole spin out to high redshift with the current generation of X-ray observatories. Here we present an analysis of a large sample of 27 lensed quasars in the redshift range 1.0 ≾ z ≾ 4.5 observed with Chandra, utilizing over 1.6 Ms of total observing time, focusing on the rest-frame iron K emission from these sources. Although the X-ray signal-to-noise ratio (S/N) currently available does not permit the detection of iron emission from the inner accretion disk in individual cases in our sample, we find significant structure in the stacked residuals. In addition to the narrow core, seen almost ubiquitously in local active galactic nuclei (AGNs), we find evidence for an additional underlying broad component from the inner accretion disk, with a clear red wing to the emission profile. Based on simulations, we find the detection of this broader component to be significant at greater than the 3σ level. This implies that iron emission from the inner disk is relatively common in the population of lensed quasars, and in turn further demonstrates that, with additional observations, this population represents an opportunity to significantly extend the sample of AGN spin measurements out to high redshift.

Additional Information

© 2015 The American Astronomical Society. Received 2014 October 29; accepted 2015 March 17; published 2015 May 29. The authors would like to thank the reviewer for providing feedback which helped improve this paper, and Julian Merten for useful discussions. The work of D.J.W./D.S. was performed at JPL/Caltech, under contract with NASA. Facility: CXO

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Published - 0004-637X_805_2_161.pdf

Submitted - 1503.05255v1.pdf


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