Intensive disc-reverberation mapping of Fairall 9 : 1st year of Swift & LCO monitoring
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We present results of time-series analysis of the first year of the Fairall 9 intensive disc-reverberation campaign. We used Swift and the Las Cumbres Observatory global telescope network to continuously monitor Fairall 9 from X-rays to near-infrared at a daily to sub-daily cadence. The cross-correlation function between bands provides evidence for a lag spectrum consistent with the τ ∝ λ4/3 scaling expected for an optically thick, geometrically thin blackbody accretion disc. Decomposing the flux into constant and variable components, the variable component's spectral energy distribution is slightly steeper than the standard accretion disc prediction. We find evidence at the Balmer edge in both the lag and flux spectra for an additional bound-free continuum contribution that may arise from reprocessing in the broad-line region. The inferred driving light curve suggests two distinct components, a rapidly variable (< 4 days) component arising from X-ray reprocessing, and a more slowly varying (> 100 days) component with an opposite lag to the reverberation signal.
Santisteban , J V H , Edelson , R , Horne , K , Gelbord , J M , Barth , A J , Cackett , E M , Goad , M R , Netzer , H , Starkey , D , Uttley , P , Brandt , W N , Korista , K , Lohfink , A M , Onken , C A , Page , K L , Siegel , M , Vestergaard , M , Bisogni , S , Breeveld , A A , Cenko , S B , Bontà , E D , Evans , P A , Ferland , G , Gonzalez-Buitrago , D H , Grupe , D , Joner , M D , Kriss , G , LaPorte , S J , Mathur , S , Marshall , F , Mehdipour , M , Mudd , D , Peterson , B M , Schmidt , T , Vaughan , S & Valenti , S 2020 , ' Intensive disc-reverberation mapping of Fairall 9 : 1st year of Swift & LCO monitoring ' , Monthly Notices of the Royal Astronomical Society , vol. 498 , no. 4 , pp. 5399–5416 . https://doi.org/10.1093/mnras/staa2365
Monthly Notices of the Royal Astronomical Society
Copyright © 2020 the Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1093/mnras/staa2222.
DescriptionFunding: UK STFC grant ST/R000824/1 (KH).
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