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

doi:10.3847/1538-4357/acbf44

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 FianAlexei 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

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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^+0.48×10²²cm⁻² to 25.6_−3.5^+3.0×10²²cm⁻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.

Original language	English
Article number	2
Number of pages	15
Journal	Astrophysical Journal
Volume	947
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/acbf44
Publication status	Published - 10 Apr 2023

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Partington, E. R., Cackett, E. M., Kara, E., Kriss, G. A., Barth, A. J., De Rosa, G., Homayouni, Y., Horne, K., Landt, H., Zoghbi, A., Edelson, R., Arav, N., Boizelle, B. D., Bentz, M. C., Brotherton, M. S., Byun, D., Dalla Bontà, E., Dehghanian, M., Du, P., ... Zaidouni, F. (2023). AGN STORM 2. III. A NICER view of the variable x-ray obscurer in Mrk 817. Astrophysical Journal, 947(1), Article 2. https://doi.org/10.3847/1538-4357/acbf44

@article{ba3945e5674a4d029e1e88e13f27e416,

title = "AGN STORM 2. III. A NICER view of the variable x-ray obscurer in Mrk 817",

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 (NH ranges from 2.85−0.33+0.48×1022cm−2 to 25.6−3.5+3.0×1022cm−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.",

author = "Partington, {Ethan R.} and Cackett, {Edward M.} and Erin Kara and Kriss, {Gerard A.} and Barth, {Aaron J.} and {De Rosa}, Gisella and Y. Homayouni and Keith Horne and Hermine Landt and Abderahmen Zoghbi and Rick Edelson and Nahum Arav and Boizelle, {Benjamin D.} and Bentz, {Misty C.} and Brotherton, {Michael S.} and Doyee Byun and {Dalla Bont{\`a}}, Elena and Maryam Dehghanian and Pu Du and Carina Fian and Filippenko, {Alexei V.} and Jonathan Gelbord and Goad, {Michael R.} and {Gonz{\'a}lez Buitrago}, {Diego H.} and Grier, {Catherine J.} and Hall, {Patrick B.} and Chen Hu and Dragana Ili{\'c} and Joner, {Michael D.} and Shai Kaspi and Kochanek, {Christopher S.} and Korista, {Kirk T.} and Kova{\v c}evi{\'c}, {Andjelka B.} and Daniel Kynoch and McLane, {Jacob N.} and Missagh Mehdipour and Miller, {Jake A.} and Christos Panagiotou and Rachel Plesha and {{\v C}. Popovi{\'c}}, Luka and Daniel Proga and Daniele Rogantini and Thaisa Storchi-Bergmann and David Sanmartim and Siebert, {Matthew R.} and Marianne Vestergaard and Ward, {Martin J.} and Tim Waters and Fatima Zaidouni",

note = "Funding: H.L. acknowledges a Daphne Jackson Fellowship sponsored by the Science and Technology Facilities Council (STFC), UK. ",

year = "2023",

month = apr,

day = "10",

doi = "10.3847/1538-4357/acbf44",

language = "English",

volume = "947",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Partington, ER, Cackett, EM, Kara, E, Kriss, GA, Barth, AJ, De Rosa, G, Homayouni, Y, Horne, K, Landt, H, Zoghbi, A, Edelson, R, Arav, N, Boizelle, BD, Bentz, MC, Brotherton, MS, Byun, D, Dalla Bontà, E, Dehghanian, M, Du, P, Fian, C, Filippenko, AV, Gelbord, J, Goad, MR, González Buitrago, DH, Grier, CJ, Hall, PB, Hu, C, Ilić, D, Joner, MD, Kaspi, S, Kochanek, CS, Korista, KT, Kovačević, AB, Kynoch, D, McLane, JN, Mehdipour, M, Miller, JA, Panagiotou, C, Plesha, R, Č. Popović, L, Proga, D, Rogantini, D, Storchi-Bergmann, T, Sanmartim, D, Siebert, MR, Vestergaard, M, Ward, MJ, Waters, T & Zaidouni, F 2023, 'AGN STORM 2. III. A NICER view of the variable x-ray obscurer in Mrk 817', Astrophysical Journal, vol. 947, no. 1, 2. https://doi.org/10.3847/1538-4357/acbf44

TY - JOUR

T1 - AGN STORM 2. III. A NICER view of the variable x-ray obscurer in Mrk 817

AU - Partington, Ethan R.

AU - Cackett, Edward M.

AU - Kara, Erin

AU - Kriss, Gerard A.

AU - Barth, Aaron J.

AU - De Rosa, Gisella

AU - Homayouni, Y.

AU - Horne, Keith

AU - Landt, Hermine

AU - Zoghbi, Abderahmen

AU - Edelson, Rick

AU - Arav, Nahum

AU - Boizelle, Benjamin D.

AU - Bentz, Misty C.

AU - Brotherton, Michael S.

AU - Byun, Doyee

AU - Dalla Bontà, Elena

AU - Dehghanian, Maryam

AU - Du, Pu

AU - Fian, Carina

AU - Filippenko, Alexei V.

AU - Gelbord, Jonathan

AU - Goad, Michael R.

AU - González Buitrago, Diego H.

AU - Grier, Catherine J.

AU - Hall, Patrick B.

AU - Hu, Chen

AU - Ilić, Dragana

AU - Joner, Michael D.

AU - Kaspi, Shai

AU - Kochanek, Christopher S.

AU - Korista, Kirk T.

AU - Kovačević, Andjelka B.

AU - Kynoch, Daniel

AU - McLane, Jacob N.

AU - Mehdipour, Missagh

AU - Miller, Jake A.

AU - Panagiotou, Christos

AU - Plesha, Rachel

AU - Č. Popović, Luka

AU - Proga, Daniel

AU - Rogantini, Daniele

AU - Storchi-Bergmann, Thaisa

AU - Sanmartim, David

AU - Siebert, Matthew R.

AU - Vestergaard, Marianne

AU - Ward, Martin J.

AU - Waters, Tim

AU - Zaidouni, Fatima

N1 - Funding: H.L. acknowledges a Daphne Jackson Fellowship sponsored by the Science and Technology Facilities Council (STFC), UK.

PY - 2023/4/10

Y1 - 2023/4/10

N2 - 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 (NH ranges from 2.85−0.33+0.48×1022cm−2 to 25.6−3.5+3.0×1022cm−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.

AB - 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 (NH ranges from 2.85−0.33+0.48×1022cm−2 to 25.6−3.5+3.0×1022cm−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.

U2 - 10.3847/1538-4357/acbf44

DO - 10.3847/1538-4357/acbf44

M3 - Article

SN - 0004-637X

VL - 947

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 2

ER -

AGN STORM 2. III. A NICER view of the variable x-ray obscurer in Mrk 817

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