Explaining the Moderate UV/X-Ray Correlation in AGN

0567474 - ASÚ 2023 RIV GB eng J - Journal Article
Panagiotou, C. - Kara, E. - Dovčiak, Michal
Explaining the Moderate UV/X-Ray Correlation in AGN.
Astrophysical Journal. Roč. 941, č. 1 (2022), č. článku 57. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA MŠMT(CZ) LTAUSA17095; GA ČR(CZ) GX21-06825X
Institutional support: RVO:67985815
Keywords : active galactic nuclei * astrophysics of galaxies * high energy astrophysical phenomena
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 4.9, year: 2022
Method of publishing: Open access

In this work, we aim to demonstrate that due to the definition of the cross-correlation function, a low UV/X-ray correlation is well expected in the case of an X-ray illuminated accretion disk, when the dynamic variability of the X-ray source is taken into account. In particular, we examine how the variability of the geometric or physical configuration of the X-ray source affects the expected correlation. Variations of the geometric configuration are found to produce a range of UV/X-ray cross correlations, which match well the observed values, while they result in a high correlation between the UV and optical variability, reconciling the observed results with theoretical predictions. We conclude that the detection of a low UV/X-ray correlation does not contradict the assumption of the UV/optical variability being driven by the X-ray illumination of the disk, and we discuss the implications of our results for correlation studies.
Permanent Link: https://hdl.handle.net/11104/0338721