X-ray bolometric corrections for Compton-thick active galactic nuclei

Creators: Brightman, M.; Baloković, M.; Ballantyne, D. R.; Bauer, F. E.; Boorman, P. G.; Buchner, J.; Brandt, W. N.; Comastri, A.; Del Moro, A.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Koss, M.; Lanz, L.; Masini, A.; Ricci, C.; Stern, D.; Vasudevan, R.; Walton, D. J.

Abstract

We present X-ray bolometric correction factors, κ_(Bol) (≡L_(Bol)/LX), for Compton-thick (CT) active galactic nuclei (AGN) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the most obscured AGN. We adopt bolometric luminosities, L_(Bol), from literature infrared (IR) torus modeling and compile published intrinsic 2–10 keV X-ray luminosities, L_X, from X-ray torus modeling of NuSTAR data. Our sample consists of 10 local CT AGN where both of these estimates are available. We test for systematic differences in κ_(Bol) values produced when using two widely used IR torus models and two widely used X-ray torus models, finding consistency within the uncertainties. We find that the mean κ_(Bol) of our sample in the range L_(Bol)≈ 10^(42)−10^(45) erg s^−1 is log_(10)κ_(Bol) = 1.44±0.12 with an intrinsic scatter of ∼ 0.2 dex, and that our derived κ_(Bol) values are consistent with previously established relationships between κ_(Bol) and L_(Bol) and κ_(Bol) and Eddington ratio (λ_(Edd)). We investigate if κ_(Bol) is dependent on N_H by comparing our results on CT AGN to published results on less-obscured AGN, finding no significant dependence. Since many of our sample are megamaser AGN, known to be viewed edge-on, and furthermore under the assumptions of AGN unification whereby unobscured AGN are viewed face-on, our result implies that the X-ray emitting corona is not strongly anisotropic. Finally, we present κ_(Bol) values for CT AGN identified in X-ray surveys as a function of their observed L_X, where an estimate of their intrinsic L_X is not available, and redshift, useful for estimating the bolometric output of the most obscured AGN across cosmic time.

Additional Information

© 2017 The American Astronomical Society. Received 2017 March 3; revised 2017 May 17; accepted 2017 May 19; published 2017 July 17. We thank the referee for providing a constructive review of our manuscript, which improved its quality. We also thank Kohei Ichikawa for insights into IR torus modeling and Almudena Alonso-Herrero and Pat Roche for providing the IR data for Figure 1. M. Baloković acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program, grant NNX14AQ07H. We acknowledge financial support from the ASI/INAF grant I/037/12/0–011/13 (A.C., A.M.) and the Caltech Kingsley visitor program (A.C.). This work was supported under NASA Contract No. NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. Furthermore, 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. Facility: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission.

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