AGN STORM 2. VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations

Autor: Maryam Dehghanian, Nahum Arav, Gerard A. Kriss, Missagh Mehdipour, Doyee Byun, Gwen Walker, Mayank Sharma, Aaron J. Barth, Misty C. Bentz, Benjamin D. Boizelle, Michael S. Brotherton, Edward M. Cackett, Elena Dalla Bontà, Gisella De Rosa, Gary J. Ferland, Carina Fian, Alexei V. Filippenko, Jonathan Gelbord, Michael R. Goad, Keith Horne, Yasaman Homayouni, Dragana Ilić, Michael D. Joner, Erin A. Kara, Shai Kaspi, Christopher S. Kochanek, Kirk T. Korista, Peter Kosec, Andjelka B. Kovačević, Hermine Landt, Collin Lewin, Ethan R. Partington, Luka Č. Popović, Daniel Proga, Daniele Rogantini, Matthew R. Siebert, Thaisa Storchi-Bergmann, Marianne Vestergaard, Timothy. Waters, Jian-Min Wang, Fatima Zaidouni, Ying Zu
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: The Astrophysical Journal, Vol 972, Iss 2, p 141 (2024)
Druh dokumentu: article
ISSN: 1538-4357
DOI: 10.3847/1538-4357/ad5ff4
Popis: We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in the Hubble Space Telescope/Cosmic Origins Spectrograph spectra, both during the campaign and in other epochs extending over 14 yr. We conclude that, while the narrow absorption outflow system (at −3750 km s ^−1 with FWHM = 177 km s ^−1 ) responds to the variations of the UV continuum as modified by the X-ray obscurer, its total column density (log N _H = 19.5 ${}_{-0.13}^{+0.61}$ cm ^−2 ) did not change across all epochs. The adjusted ionization parameter (scaled with respect to the variations in the hydrogen-ionizing continuum flux) is log U _H = −1.0 ${}_{-0.3}^{+0.1}$ . The outflow is located at a distance smaller than 38 pc from the central source, which implies a hydrogen density of n _H > 3000 cm ^−3 . The absorption outflow system only covers the continuum emission source and not the broad emission line region, which suggests that its transverse size is small (< 10 ^16 cm), with potential cloud geometries ranging from spherical to elongated along the line of sight.
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