Intensive broadband reverberation mapping of Fairall 9 with 1.7 years of daily Swift monitoring
Abstract
I will present 1.7 years of near-daily Swift X-ray/UV/optical monitoring of the bright, strongly variable Type 1 AGN Fairall 9. This is the largest such Swift AGN monitoring campaign reported to date, yielding the first clear measurement by Swift of lags throughout the near-UV/optical. Interpolated cross-correlation functions were measured, and detailed analysis indicates that the safest and most effective detrending approach is to do nothing to the X-rays and perform a simple first-order (straight line) detrending in the UV/optical. Because this dataset is so extensive, we were able to measure separate lag spectra during periods of low and high UV fluxes. Overall the high flux lag spectrum show longer lags, as expected, but the U-band excess lag is largest when the flux is low. This indicates that both thermal continuum emission from the accretion disk and "diffuse continuum" emission from the broad-line region contribute to the observed lag spectra. I will conclude with suggestions for new time-series analytical tools that can more fully extract the physical information contained in this rich dataset, and the design of new campaigns that fully utilize the capabilities of Swift, ground-based robotic telescopes and NICER.
- Publication:
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44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44.2292E