Is there a UV/X-ray connection in IRAS 13224−3809?
We present results from the optical, ultraviolet, and X-ray monitoring of the NLS1 galaxy IRAS 13224−3809 taken with Swift and XMM–Newton during 2016. IRAS 13224−3809 is the most variable bright AGN in the X-ray sky and shows strong X-ray reflection, implying that the X-rays strongly illuminate the inner disc. Therefore, it is a good candidate to study the relationship between coronal X-ray and disc UV emission. However, we find no correlation between the X-ray and UV flux over the available ∼40 d monitoring, despite the presence of strong X-ray variability and the variable part of the UV spectrum being consistent with irradiation of a standard thin disc. This means either that the X-ray flux which irradiates the UV emitting outer disc does not correlate with the X-ray flux in our line of sight and/or that another process drives the majority of the UV variability. The former case may be due to changes in coronal geometry, absorption or scattering between the corona and the disc.
Additional Information© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 December 22. Received 2017 December 18; in original form 2017 October 2. Published: 05 January 2018. We thank the referee for comments which have helped to improve the clarity of the paper. DJKB acknowledges financial support from the Science and Technology Facilities Council (STFC). ACF, AML, and MLP acknowledge support from the ERC Advanced Grant FEEDBACK 340442. BDM acknowledges support from the Polish National Science Center grant Polonez 2016/21/P/ST9/04025. This work has made use of observations obtained with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.
Published - sty008.pdf
Submitted - 1712.06606.pdf