The Rhythm of Fairall 9. I. Observing the Spectral Variability with XMM-Newton and NuSTAR

A. M. Lohfink, C. S. Reynolds, C. Pinto, W. Alston, S. E. Boggs, Finn Erland Christensen, W. W. Craig, A. C. Fabian, C. J. Hailey, F. A. Harrison, E. Kara, G. Matt, M. L. Parker, D. Stern, D. Walton, W. W. Zhang

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We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.5–10 keV band remain constant with time in spite of large variations in flux. This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred ionized reflection in the innermost parts of the accretion disk, and the other a continuum component such as a spatially distinct Comptonizing region. Alternatively, a more complex primary Comptonization component together with blurred ionized reflection could be responsible.
Original languageEnglish
Article number11
JournalAstrophysical Journal
Issue number1
Number of pages11
Publication statusPublished - 2016

Bibliographical note

© 2016. The American Astronomical Society. All rights reserved.


  • Galaxies
  • Active - galaxies
  • Seyfert - X-rays
  • Individual (fairall 9)

Cite this

Lohfink, A. M., Reynolds, C. S., Pinto, C., Alston, W., Boggs, S. E., Christensen, F. E., Craig, W. W., Fabian, A. C., Hailey, C. J., Harrison, F. A., Kara, E., Matt, G., Parker, M. L., Stern, D., Walton, D., & Zhang, W. W. (2016). The Rhythm of Fairall 9. I. Observing the Spectral Variability with XMM-Newton and NuSTAR. Astrophysical Journal, 821(1), [11].