AGN STORM 2: II. Ultraviolet Observations of Mrk817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope
Creators: name: Homayouni, Y.
name: De Rosa, Gisella
name: Plesha, Rachel
name: Kriss, Gerard A.
name: Barth, Aaron J.
name: Cackett, Edward M.
name: Horne, Keith
name: Kara, Erin A.
name: Landt, Hermine
name: Arav, Nahum
name: Boizelle, Benjamin D.
name: Bentz, Misty C.
name: Brink, Thomas G.
name: Brotherton, Michael S.
name: Chelouche, Doron
name: Bonta, Elena Dalla
name: Dehghanian, Maryam
name: Du, Pu
name: Ferland, Gary J.
name: Ferrarese, Laura
name: Fian, Carina
name: Filippenko, Alexei V.
name: Fischer, Travis
name: Foley, Ryan J.
name: Gelbord, Jonathan
name: Goad, Michael R.
name: Buitrago, Diego H. Gonzalez
name: Gorjian, Varoujan
name: Grier, Catherine J.
name: Hall, Patrick B.
name: Santisteban, Juan V. Hernandez
name: Hu, Chen
name: Ilic, Dragana
name: Joner, Michael D.
name: Kaastra, Jelle
name: Kaspi, Shai
name: Kochanek, Christopher S.
name: Korista, Kirk T.
name: Kovacevic, Andjelka B.
name: Kynoch, Daniel
name: Li, Yan-Rong
name: McHardy, Ian M.
name: McLane, Jacob N.
name: Mehdipour, Missagh
name: Miller, Jake A.
name: Mitchell, Jake
name: Montano, John
name: Netzer, Hagai
name: Panagiotou, Christos
name: Partington, Ethan
name: Pogge, Richard W.
name: Popovic, Luka C.
name: Proga, Daniel
name: Rogantini, Daniele
name: Storchi-Bergmann, Thaisa
name: Sanmartim, David
name: Siebert, Matthew R.
name: Treu, Tommaso
name: Vestergaard, Marianne
name: Wang, Jian-Min
name: Ward, Martin J.
name: Waters, Tim
name: Williams, Peter R.
name: Zaidouni, Fatima
name: Zu, Ying
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultraviolet observations are accompanied by X-ray, optical, and near-infrared observations as part of the AGN Space Telescope and Optical Reverberation Mapping Program 2 (AGN STORM 2). Using the cross-correlation lag analysis method, we find significant correlated variations in the continuum and emission-line light curves. We measure rest-frame delayed responses between the far-ultraviolet continuum at 1180 A and Ly$α$ $\lambda1215$ A ($10.4_{-1.4}^{+1.6}$ days), N V $\lambda1240$ A ($15.5_{-4.8}^{+1.0}$days), SiIV + OIV] $\lambda1397$ A ($8.2_{-1.4}^{+1.4}$ days), CIV $\lambda1549$ A ($11.8_{-2.8}^{+3.0}$ days), and HeII $\lambda1640$ A ($9.0_{-1.9}^{+4.5}$ days) using segments of the emission-line profile that are unaffected by absorption and blending, which results in sampling different velocity ranges for each line. However, we find that the emission-line responses to continuum variations are more complex than a simple smoothed, shifted, and scaled version of the continuum light curve. We also measure velocity-resolved lags for the Ly$α$, and CIV emission lines. The lag profile in the blue wing of Ly$α$ is consistent with virial motion, with longer lags dominating at lower velocities, and shorter lags at higher velocities. The CIV lag profile shows the signature of a thick rotating disk, with the shortest lags in the wings, local peaks at $\pm$ 1500 $\rm km\,s^{-1}$, and a local minimum at line center. The other emission lines are dominated by broad absorption lines and blending with adjacent emission lines. These require detailed models, and will be presented in future work.
description: Submitted to ApJ. 25 pages, 8 figures, and 6 tables