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Chandra Observations of Candidate Sub-Parsec Binary Supermassive Black Holes

Saade, M. Lynne and Stern, Daniel and Brightman, Murray and Haiman, Zoltán and Djorgovski, S. G. and D'Orazio, Daniel and Ford, K. E. S. and Graham, Matthew J. and Jun, Hyunsung D. and Kraft, Ralph P. and McKernan, Barry and Vikhlinin, Alexei and Walton, Dominic J. (2020) Chandra Observations of Candidate Sub-Parsec Binary Supermassive Black Holes. . (Unpublished) https://resolver.caltech.edu/CaltechAUTHORS:20200413-151905111

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Abstract

We present analysis of Chandra X-ray observations of seven quasars that were identified as candidate sub-parsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey (CRTS) based on apparent periodicity in their optical light curves. Simulations predict close-separation accreting SMBH binaries will have different X-ray spectra than single accreting SMBHs, including harder or softer X-ray spectra, ripple-like profiles in the Fe K-α line, and distinct peaks in the spectrum due to the separation of the accretion disk into a circumbinary disk and mini-disks around each SMBH. We obtained Chandra observations to test these models and assess whether these quasars could contain binary SMBHs. We instead find that the quasar spectra are all well fit by simple absorbed power law models, with the rest frame 2-10 keV photon indices, Γ, and the X-ray-to-optical power slopes, α_(OX), indistinguishable from the larger quasar population. This may indicate that these seven quasars are not truly sub-parsec binary SMBH systems, or it may simply reflect that our sample size was too small to robustly detect any differences. Alternatively, the X-ray spectral changes might only be evident at higher energies than probed by Chandra. Given the available models and current data, no firm conclusions are drawn. These observations will help motivate and direct further work on theoretical models of binary SMBH systems, such as modeling systems with thinner accretion disks and larger binary separations.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/2001.08870arXivDiscussion Paper
ORCID:
AuthorORCID
Stern, Daniel0000-0003-2686-9241
Brightman, Murray0000-0002-8147-2602
Haiman, Zoltán0000-0003-3633-5403
Djorgovski, S. G.0000-0002-0603-3087
Graham, Matthew J.0000-0002-3168-0139
Jun, Hyunsung D.0000-0003-1470-5901
Kraft, Ralph P.0000-0002-0765-0511
McKernan, Barry0000-0002-9726-0508
Walton, Dominic J.0000-0001-5819-3552
Additional Information:Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Chandra Award Number 18700580 issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the NASA under contract NAS8-03060. The work of DS was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. ZH acknowledges support from NSF grant 1715661 and NASA grants 80NSSC19K0149 and NNX17AL82G. MJG and SGD were supported in part by the NASA grant 16-ADAP16-0232, and the NSF grants AST-1413600, AST-1518308, and AST-1749235. DJD acknowledges funding from the Institute for Theory and Computation Fellowship. KESF and BM were supported by NSF grant 1831412. HDJ was supported by the Basic Science Research Program through the National Research Foundation of Korea, funded by the Ministry of Education (NRF-2017R1A6A3A04005158).
Group:Astronomy Department, Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASA Chandra18700580
Smithsonian Astrophysical ObservatoryUNSPECIFIED
NASANAS8-03060
NASA/JPL/CaltechUNSPECIFIED
NSFAST-1715661
NASA80NSSC19K0149
NASANNX17AL82G
NASA16-ADAP16-0232
NSFAST-1413600
NSFAST-1518308
NSFAST-1749235
Institute for Theory and ComputationUNSPECIFIED
NSFAST-1831412
National Research Foundation of KoreaNRF-2017R1A6A3A04005158
Subject Keywords:quasars: general - galaxies: active - galaxies: nuclei - quasars: supermassive black holes - X-rays: galaxies
Record Number:CaltechAUTHORS:20200413-151905111
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200413-151905111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102510
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Apr 2020 22:40
Last Modified:13 Apr 2020 22:40

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