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

Kara, Erin; Mehdipour, Missagh; Kriss, Gerard A.; Cackett, Edward M.; Arav, Nahum; Barth, Aaron J.; Byun, Doyee; Brotherton, Michael S.; De Rosa, Gisella; Gelbord, Jonathan; Hernández Santisteban, Juan V.; Hu, Chen; Kaastra, Jelle; Landt, Hermine; Li, Yan-Rong; Miller, Jake A.; Montano, John; Partington, Ethan; Aceituno, Jesús; Bai, Jin-Ming; Bao, Dongwei; Bentz, Misty C.; Brink, Thomas G.; Chelouche, Doron; Chen, Yong-Jie; Colmenero, Encarni Romero; Bontà, Elena Dalla; Dehghanian, Maryam; Du, Pu; Edelson, Rick; Ferland, Gary J.; Ferrarese, Laura; Fian, Carina; Filippenko, Alexei V.; Fischer, Travis; Goad, Michael R.; González Buitrago, Diego H.; Gorjian, Varoujan; Grier, Catherine J.; Guo, Wei-Jian; Hall, Patrick B.; Ho, Luis C.; Homayouni, Y.; Horne, Keith; Ilić, Dragana; Jiang, Bo-Wei; Joner, Michael D.; Kaspi, Shai; Kochanek, Christopher S.; Korista, Kirk T.; Kynoch, Daniel; Li, Sha-Sha; Liu, Jun-Rong; M. cHardy, Ian M.; McLane, Jacob N.; Mitchell, Jake A.J.; Netzer, Hagai; Olson,...

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Erin Kara

Missagh Mehdipour

Gerard A. Kriss

Edward M. Cackett

Nahum Arav

Aaron J. Barth

Doyee Byun

Michael S. Brotherton

Gisella De Rosa

Jonathan Gelbord

Juan V. Hernández Santisteban

Chen Hu

Jelle Kaastra

Yan-Rong Li

Jake A. Miller

John Montano

Ethan Partington

Jesús Aceituno

Jin-Ming Bai

Dongwei Bao

Misty C. Bentz

Thomas G. Brink

Doron Chelouche

Yong-Jie Chen

Encarni Romero Colmenero

Elena Dalla Bontà

Maryam Dehghanian

Pu Du

Rick Edelson

Gary J. Ferland

Laura Ferrarese

Carina Fian

Alexei V. Filippenko

Travis Fischer

Michael R. Goad

Diego H. González Buitrago

Varoujan Gorjian

Catherine J. Grier

Wei-Jian Guo

Patrick B. Hall

Luis C. Ho

Y. Homayouni

Keith Horne

Dragana Ilić

Bo-Wei Jiang

Michael D. Joner

Shai Kaspi

Christopher S. Kochanek

Kirk T. Korista

Daniel Kynoch

Sha-Sha Li

Jun-Rong Liu

Ian M. M. cHardy

Jacob N. McLane

Jake A.J. Mitchell

Hagai Netzer

Kianna A. Olson

Richard W. Pogge

Luka C̆ Popović

Daniel Proga

Thaisa Storchi-Bergmann

Erika Strasburger

Tommaso Treu

Marianne Vestergaard

Jian-Min Wang

Martin J. Ward

Tim Waters

Peter R. Williams

Sen Yang

Zhu-Heng Yao

Theodora E. Zastrocky

Shuo Zhai

Ying Zu


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 Lyα lags suggest that the accretion disk extends beyond the UV broad-line region. Unified A


Kara, E., Mehdipour, M., Kriss, G. A., Cackett, E. M., Arav, N., Barth, A. J., …Zu, Y. (2021). AGN STORM 2. I. First results: A Change in the Weather of Mrk 817. Astrophysical Journal, 922(2), Article 151.

Journal Article Type Article
Acceptance Date Jul 8, 2021
Online Publication Date Nov 26, 2021
Publication Date Dec 1, 2021
Deposit Date Jan 18, 2022
Publicly Available Date Jan 19, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 922
Issue 2
Article Number 151
Public URL


Published Journal Article (3.8 Mb)

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© 2021. The American Astronomical Society. All rights reserved

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