AGN STORM 2. III. A NICER view of the variable X-ray obscurer in Mrk 817
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arXiv
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| Natura: | Preprint |
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2023
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| author | Partington, Ethan R. Cackett, Edward M. Kara, Erin Kriss, Gerard A. Barth, Aaron J. De Rosa, Gisella Homayouni, Y. Horne, Keith Landt, Hermine Zoghbi, Abderahmen Edelson, Rick Arav, Nahum Boizelle, Benjamin D. Bentz, Misty C. Brotherton, Michael S. Byun, Doyee Bonta, Elena Dalla Dehghanian, Maryam Du, Pu Fian, Carina Filippenko, Alexei V. Gelbord, Jonathan Goad, Michael R. Buitrago, Diego H. Gonzalez Grier, Catherine J. Hall, Patrick B. Hu, Chen Ilic, Dragana Joner, Michael D. Kochanek, Shai Kaspi Christopher S. Korista, Kirk T. Kovacevic, Andjelka B. Kynoch, Daniel McLane, Jacob N. Mehdipour, Missagh Panagiotou, Jake A. Miller Christos Plesha, Rachel Popovic, Luka C. Proga, Daniel Rogantini, Daniele Storchi-Bergmann, Thaisa Sanmartim, David Siebert, Matthew R. Vestergaard, Marianne Ward, Martin J. Waters, Tim Zaidouni, Fatima |
| author_facet | Partington, Ethan R. Cackett, Edward M. Kara, Erin Kriss, Gerard A. Barth, Aaron J. De Rosa, Gisella Homayouni, Y. Horne, Keith Landt, Hermine Zoghbi, Abderahmen Edelson, Rick Arav, Nahum Boizelle, Benjamin D. Bentz, Misty C. Brotherton, Michael S. Byun, Doyee Bonta, Elena Dalla Dehghanian, Maryam Du, Pu Fian, Carina Filippenko, Alexei V. Gelbord, Jonathan Goad, Michael R. Buitrago, Diego H. Gonzalez Grier, Catherine J. Hall, Patrick B. Hu, Chen Ilic, Dragana Joner, Michael D. Kochanek, Shai Kaspi Christopher S. Korista, Kirk T. Kovacevic, Andjelka B. Kynoch, Daniel McLane, Jacob N. Mehdipour, Missagh Panagiotou, Jake A. Miller Christos Plesha, Rachel Popovic, Luka C. Proga, Daniel Rogantini, Daniele Storchi-Bergmann, Thaisa Sanmartim, David Siebert, Matthew R. Vestergaard, Marianne Ward, Martin J. Waters, Tim Zaidouni, Fatima |
| contents | The AGN STORM 2 collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including HST, Swift, XMM-Newton, NICER, and ground-based observatories. Early observations with NICER and XMM revealed an X-ray state ten 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 ($N_\mathrm{H}$ ranges from $2.85\substack{+0.48\\ -0.33} \times 10^{22}\text{ cm}^{-2}$ to $25.6\substack{+3.0\\ -3.5} \times 10^{22} \text{ cm}^{-2}$) 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2302_12896 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | AGN STORM 2. III. A NICER view of the variable X-ray obscurer in Mrk 817 Partington, Ethan R. Cackett, Edward M. Kara, Erin Kriss, Gerard A. Barth, Aaron J. De Rosa, Gisella Homayouni, Y. Horne, Keith Landt, Hermine Zoghbi, Abderahmen Edelson, Rick Arav, Nahum Boizelle, Benjamin D. Bentz, Misty C. Brotherton, Michael S. Byun, Doyee Bonta, Elena Dalla Dehghanian, Maryam Du, Pu Fian, Carina Filippenko, Alexei V. Gelbord, Jonathan Goad, Michael R. Buitrago, Diego H. Gonzalez Grier, Catherine J. Hall, Patrick B. Hu, Chen Ilic, Dragana Joner, Michael D. Kochanek, Shai Kaspi Christopher S. Korista, Kirk T. Kovacevic, Andjelka B. Kynoch, Daniel McLane, Jacob N. Mehdipour, Missagh Panagiotou, Jake A. Miller Christos Plesha, Rachel Popovic, Luka C. Proga, Daniel Rogantini, Daniele Storchi-Bergmann, Thaisa Sanmartim, David Siebert, Matthew R. Vestergaard, Marianne Ward, Martin J. Waters, Tim Zaidouni, Fatima High Energy Astrophysical Phenomena Astrophysics of Galaxies The AGN STORM 2 collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including HST, Swift, XMM-Newton, NICER, and ground-based observatories. Early observations with NICER and XMM revealed an X-ray state ten 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 ($N_\mathrm{H}$ ranges from $2.85\substack{+0.48\\ -0.33} \times 10^{22}\text{ cm}^{-2}$ to $25.6\substack{+3.0\\ -3.5} \times 10^{22} \text{ cm}^{-2}$) 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. |
| title | AGN STORM 2. III. A NICER view of the variable X-ray obscurer in Mrk 817 |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2302.12896 |