The Astrophysical Journal (Jan 2023)
AGN STORM 2. III. A NICER View of the Variable X-Ray Obscurer in Mrk 817
- Ethan R. Partington,
- Edward M. Cackett,
- Erin Kara,
- Gerard A. Kriss,
- Aaron J. Barth,
- Gisella De Rosa,
- Y. Homayouni,
- Keith Horne,
- Hermine Landt,
- Abderahmen Zoghbi,
- Rick Edelson,
- Nahum Arav,
- Benjamin D. Boizelle,
- Misty C. Bentz,
- Michael S. Brotherton,
- Doyee Byun,
- Elena Dalla Bontà,
- Maryam Dehghanian,
- Pu Du,
- Carina Fian,
- Alexei V. Filippenko,
- Jonathan Gelbord,
- Michael R. Goad,
- Diego H. González Buitrago,
- Catherine J. Grier,
- Patrick B. Hall,
- Chen Hu,
- Dragana Ilić,
- Michael D. Joner,
- Shai Kaspi,
- Christopher S. Kochanek,
- Kirk T. Korista,
- Andjelka B. Kovačević,
- Daniel Kynoch,
- Jacob N. McLane,
- Missagh Mehdipour,
- Jake A. Miller,
- Christos Panagiotou,
- Rachel Plesha,
- Luka Č. Popović,
- Daniel Proga,
- Daniele Rogantini,
- Thaisa Storchi-Bergmann,
- David Sanmartim,
- Matthew R. Siebert,
- Marianne Vestergaard,
- Martin J. Ward,
- Tim Waters,
- Fatima Zaidouni
Affiliations
- Ethan R. Partington
- ORCiD
- Department of Physics and Astronomy, Wayne State University , 666 W. Hancock Street, Detroit, MI 48201, USA
- Edward M. Cackett
- ORCiD
- Department of Physics and Astronomy, Wayne State University , 666 W. Hancock Street, Detroit, MI 48201, USA
- Erin Kara
- ORCiD
- MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Gerard A. Kriss
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Aaron J. Barth
- ORCiD
- Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California , Irvine, CA 92697-4575, USA
- Gisella De Rosa
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Y. Homayouni
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Astronomy and Astrophysics, The Pennsylvania State University , 525 Davey Laboratory, University Park, PA 16802, USA; Institute for Gravitation and the Cosmos, The Pennsylvania State University , University Park, PA 16802, USA
- Keith Horne
- ORCiD
- SUPA School of Physics and Astronomy , North Haugh, St. Andrews, KY16 9SS, Scotland, UK
- Hermine Landt
- Centre for Extragalactic Astronomy, Department of Physics, Durham University , South Road, Durham DH1 3LE, UK
- Abderahmen Zoghbi
- ORCiD
- Department of Astronomy, University of Maryland , 4296 Stadium Drive, College Park, MD 20742, USA; HEASARC , Code 6601, NASA/GSFC, Greenbelt, MD 20771, USA; CRESST II, NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Rick Edelson
- ORCiD
- Eureka Scientific Inc. , 2452 Delmer St. Suite 100, Oakland, CA 94602, USA
- Nahum Arav
- ORCiD
- Department of Physics , Virginia Tech, Blacksburg, VA 24061, USA
- Benjamin D. Boizelle
- ORCiD
- Department of Physics and Astronomy, N284 ESC, Brigham Young University , Provo, UT 84602, USA
- Misty C. Bentz
- ORCiD
- Department of Physics and Astronomy, Georgia State University , 25 Park Place, Suite 605, Atlanta, GA 30303, USA
- Michael S. Brotherton
- ORCiD
- Department of Physics and Astronomy, University of Wyoming , Laramie, WY 82071, USA
- Doyee Byun
- ORCiD
- Department of Physics , Virginia Tech, Blacksburg, VA 24061, USA
- Elena Dalla Bontà
- ORCiD
- Dipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova , Vicolo dell’Osservatorio 3, I-35122 Padova, Italy; INAF-Osservatorio Astronomico di Padova , Vicolo dell’Osservatorio 5 I-35122, Padova, Italy
- Maryam Dehghanian
- ORCiD
- Department of Physics , Virginia Tech, Blacksburg, VA 24061, USA
- Pu Du
- ORCiD
- Key Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People's Republic of China
- Carina Fian
- ORCiD
- Haifa Research Center for Theoretical Physics and Astrophysics, University of Haifa , Haifa 3498838, Israel; School of Physics and Astronomy and Wise Observatory, Tel Aviv University , Tel Aviv 6997801, Israel
- Alexei V. Filippenko
- ORCiD
- Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
- Jonathan Gelbord
- ORCiD
- Spectral Sciences Inc. , 4 Fourth Ave., Burlington, MA 01803, USA
- Michael R. Goad
- ORCiD
- School of Physics and Astronomy, University of Leicester , University Road, Leicester, LE1 7RH, UK
- Diego H. González Buitrago
- ORCiD
- Instituto de Astronomía, Universidad Nacional Autónoma de México , Km 103 Carretera Tijuana-Ensenada, 22860 Ensenada B.C., México
- Catherine J. Grier
- ORCiD
- Department of Astronomy, University of Wisconsin-Madison , Madison, WI 53706, USA
- Patrick B. Hall
- ORCiD
- Department of Physics and Astronomy, York University , Toronto, ON M3J 1P3, Canada
- Chen Hu
- Key Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People's Republic of China
- Dragana Ilić
- ORCiD
- University of Belgrade—Faculty of Mathematics , Department of Astronomy, Studentski trg 16, 11000 Belgrade, Serbia; Humboldt Research Fellow, Hamburger Sternwarte, Universität Hamburg , Gojenbergsweg 112, D-21029 Hamburg, Germany
- Michael D. Joner
- ORCiD
- Department of Physics and Astronomy, N284 ESC, Brigham Young University , Provo, UT 84602, USA
- Shai Kaspi
- ORCiD
- School of Physics and Astronomy and Wise Observatory, Tel Aviv University , Tel Aviv 6997801, Israel
- Christopher S. Kochanek
- ORCiD
- Department of Astronomy, The Ohio State University , 140 W. 18th Avenue, Columbus, OH 43210, USA; Center for Cosmology and AstroParticle Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USA
- Kirk T. Korista
- ORCiD
- Department of Physics, Western Michigan University , 1120 Everett Tower, Kalamazoo, MI 49008-5252, USA
- Andjelka B. Kovačević
- ORCiD
- University of Belgrade—Faculty of Mathematics , Department of Astronomy, Studentski trg 16, 11000 Belgrade, Serbia; PIFI Research Fellow, Key Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences,19B Yuquan Road, 100049 Beijing, People's Republic of China
- Daniel Kynoch
- ORCiD
- School of Physics and Astronomy, University of Southampton , Highfield, Southampton SO17 1BJ, UK; Astronomical Institute of the Czech Academy of Sciences , Boční II 1401/1a, CZ-14100 Prague, Czechia
- Jacob N. McLane
- ORCiD
- Department of Physics and Astronomy, University of Wyoming , Laramie, WY 82071, USA
- Missagh Mehdipour
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Jake A. Miller
- ORCiD
- Department of Physics and Astronomy, Wayne State University , 666 W. Hancock Street, Detroit, MI 48201, USA
- Christos Panagiotou
- MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Rachel Plesha
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Luka Č. Popović
- ORCiD
- University of Belgrade—Faculty of Mathematics , Department of Astronomy, Studentski trg 16, 11000 Belgrade, Serbia; PIFI Research Fellow, Key Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences,19B Yuquan Road, 100049 Beijing, People's Republic of China; Astronomical Observatory , Volgina 7, 11060 Belgrade, Serbia
- Daniel Proga
- ORCiD
- Department of Physics & Astronomy, University of Nevada , Las Vegas 4505 S. Maryland Parkway, Las Vegas, NV 89154-4002, USA
- Daniele Rogantini
- ORCiD
- MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Thaisa Storchi-Bergmann
- ORCiD
- Departamento de Astronomia—IF, Universidade Federal do Rio Grande do Sul , CP 150501, 91501-970 Porto Alegre, RS, Brazil
- David Sanmartim
- ORCiD
- Carnegie Observatories , Las Campanas Observatory, Casilla 601, La Serena, Chile
- Matthew R. Siebert
- ORCiD
- Department of Astronomy and Astrophysics, University of California , Santa Cruz, CA 92064, USA
- Marianne Vestergaard
- ORCiD
- Steward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA; DARK, The Niels Bohr Institute, University of Copenhagen , Universitetsparken 5, DK-2100 Copenhagen, Denmark
- Martin J. Ward
- ORCiD
- Centre for Extragalactic Astronomy, Department of Physics, Durham University , South Road, Durham DH1 3LE, UK
- Tim Waters
- ORCiD
- Department of Physics & Astronomy, University of Nevada , Las Vegas 4505 S. Maryland Parkway, Las Vegas, NV 89154-4002, USA
- Fatima Zaidouni
- ORCiD
- MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- DOI
- https://doi.org/10.3847/1538-4357/acbf44
- Journal volume & issue
-
Vol. 947,
no. 1
p. 2
Abstract
The AGN STORM 2 Collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including Hubble Space Telescope, Swift, XMM-Newton, NICER, and ground-based observatories. Early observations with NICER and XMM revealed an X-ray state 10 times fainter than historical observations, consistent with the presence of a new dust-free, ionized obscurer. The following analysis of NICER spectra attributes variability in the observed X-ray flux to changes in both the column density of the obscurer by at least one order of magnitude ( N _H ranges from ${2.85}_{-0.33}^{+0.48}\times {10}^{22}\,{\mathrm{cm}}^{-2}$ to ${25.6}_{-3.5}^{+3.0}\times {10}^{22}\,{\mathrm{cm}}^{-2}$ ) and the intrinsic continuum brightness (the unobscured flux ranges from 10 ^−11.8 to 10 ^−10.5 erg s ^−1 cm ^−2 ). While the X-ray flux generally remains in a faint state, there is one large flare during which Mrk 817 returns to its historical mean flux. The obscuring gas is still present at lower column density during the flare, but it also becomes highly ionized, increasing its transparency. Correlation between the column density of the X-ray obscurer and the strength of UV broad absorption lines suggests that the X-ray and UV continua are both affected by the same obscuration, consistent with a clumpy disk wind launched from the inner broad-line region.
Keywords
