AGN STORM 2. I. First results: A Change in the Weather of Mrk 817

0552230 - ASÚ 2022 RIV GB eng J - Journal Article
Kara, E. - Mehdipour, M. - Kriss, G. A. - Kynoch, Daniel … Total 74 authors
AGN STORM 2. I. First results: A Change in the Weather of Mrk 817.
Astrophysical Journal. Roč. 922, č. 1 (2021), č. článku 151. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GJ19-05599Y
Institutional support: RVO:67985815
Keywords : high energy astrophysical phenomena * astrophysics of galaxies * active galactic nuclei
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.521, year: 2021
Method of publishing: Limited access
https://doi.org/10.3847/1538-4357/ac2159

We present the first results from the ongoing, intensive, multiwavelength monitoring program of the luminous Seyfert 1 galaxy Mrk 817. While this active galactic nucleus was, in part, selected for its historically unobscured nature, we discovered that the X-ray spectrum is highly absorbed, and there are new blueshifted, broad, and narrow UV absorption lines, which suggest that a dust-free, ionized obscurer located at the inner broad-line region partially covers the central source. Despite the obscuration, we measure UV and optical continuum reverberation lags consistent with a centrally illuminated Shakura-Sunyaev thin accretion disk, and measure reverberation lags associated with the optical broad-line region, as expected. However, in the first 55 days of the campaign, when the obscuration was becoming most extreme, we observe a de-coupling of the UV continuum and the UV broad emission-line variability. The correlation recovered in the next 42 days of the campaign, as Mrk 817 entered a less obscured state. The short C iv and Ly alpha lags suggest that the accretion disk extends beyond the UV broad-line region.
Permanent Link: http://hdl.handle.net/11104/0327368