AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy

Fatima Zaidouni, Erin Kara, Peter Kosec, Missagh Mehdipour, Daniele Rogantini, Gerard A. Kriss, Ehud Behar, Jelle Kaastra, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa, Yasaman Homayouni, Keith Horne, Hermine Landt, Nahum Arav, Misty C. Bentz, Michael S. Brotherton, Elena Dalla Bonta, Maryam Dehghanian, Gary J. FerlandCarina Fian, Jonathan Gelbord, Michael R. Goad, Diego H. GonzAlez Buitrago, Catherine J. Grier, Patrick B. Hall, Chen Hu, Dragana Ilic, Shai Kaspi, Christopher S. Kochanek, Andjelka B. Kovacevic, Daniel Kynoch, Collin Lewin, John Montano, Hagai Netzer, Jack M.M. Neustadt, Christos Panagiotou, Ethan R. Partington, Rachel Plesha, Luka C. Popovic, Daniel Proga, Thaisa Storchi-Bergmann, David Sanmartim, Matthew R. Siebert, Matilde Signorini, Marianne Vestergaard, Tim Waters, Ying Zu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multiwavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AGN STORM 2) Project. The campaign revealed an unexpected and transient obscuring outflow, never before seen in this source. Of our four XMM-Newton/NuSTAR epochs, one fortuitously taken during a bright X-ray state has strong narrow absorption lines in the high-resolution grating spectra. From these absorption features, we determine that the obscurer is in fact a multiphase ionized wind with an outflow velocity of ∼5200 km s−1, and for the first time find evidence for a lower ionization component with the same velocity observed in absorption features in the contemporaneous Hubble Space Telescope spectra. This indicates that the UV absorption troughs may be due to dense clumps embedded in diffuse, higher ionization gas responsible for the X-ray absorption lines of the same velocity. We observe variability in the shape of the absorption lines on timescales of hours, placing the variable component at roughly 1000 R g if attributed to transverse motion along the line of sight. This estimate aligns with independent UV measurements of the distance to the obscurer suggesting an accretion disk wind at the inner broad line region. We estimate that it takes roughly 200 days for the outflow to travel from the disk to our line of sight, consistent with the timescale of the outflow's column density variations throughout the campaign.

Original languageEnglish
Article number91
JournalAstrophysical Journal
Volume974
Issue number1
DOIs
StatePublished - 1 Oct 2024

Funding

FundersFunder number
University of Belgrade-Faculty of Mathematics
Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja
Alexander von Humboldt-Stiftung
University of Belgrade451-03-47/2023-01/200104
National Science FoundationAST-1907290
Independent Research Fund DenmarkDFF 8021-00130
Astronomical Observatory Belgrade451-03-47/2023-01/200002
National Aeronautics and Space Administration80NSSC22K0570
Chinese Academy of SciencesAST-2307385
Space Telescope Science InstituteNAS5-26555
Science and Technology Facilities CouncilAST-2009230

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