TY - JOUR
T1 - AGN STORM 2. X. The origin of the interband continuum delays in Mrk 817
AU - Netzer, Hagai
AU - Goad, Michael R.
AU - Barth, Aaron J.
AU - Cackett, Edward M.
AU - Horne, Keith
AU - Hu, Chen
AU - Kara, Erin
AU - Korista, Kirk T.
AU - Kriss, Gerard A.
AU - Lewin, Collin
AU - Montano, John
AU - Arav, Nahum
AU - Behar, Ehud
AU - Brotherton, Michael S.
AU - Chelouche, Doron
AU - De Rosa, Gisella
AU - Dalla Bontà, Elena
AU - Dehghanian, Maryam
AU - Ferland, Gary J.
AU - Fian, Carina
AU - Homayouni, Yasaman
AU - Ilić, Dragana
AU - Kaspi, Shai
AU - Kovačević, Andjelka B.
AU - Landt, Hermine
AU - Č. Popović, Luka
AU - Storchi-Bergmann, Thaisa
AU - Wang, Jian-Min
AU - Zaidouni, Fatima
N1 - Funding: D.I., A.B.K, and L.Č.P. acknowledge funding provided by the University of Belgrade Faculty of Mathematics (contract 451-03-66/2024-03/200104) and Astronomical Observatory Belgrade (contract 451-03-66/2024-03/200002), through grants by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. D.I. acknowledges the support of the Alexander von Humboldt Foundation. A.B.K. and L.Č.P. are grateful for the support from the Chinese Academy of Science's Presidentʼs International Fellowship Initiative (PIFI) for visiting scientists. N.A. acknowledges support from NSF grant AST 2106249 and NASA STScI grants AR-15786, AR-16600, AR-16601, and HST-AR-17556. G.K. and G.D.R acknowledge support from STScI grant GO-16196.
PY - 2024/11/30
Y1 - 2024/11/30
N2 - The local (z = 0.0315) active galactic nucleus (AGN) Mrk 817 was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign, AGN STORM 2. Here, we present a comprehensive analysis of the broadband continuum variations using detailed modeling of the broad line region (BLR), several types of disk winds classified by their optical depth, and new numerical simulations. We find that diffuse continuum (DC) emission, with additional contributions from strong and broad emission lines, can explain the continuum lags observed in this source during high- and low-luminosity phases. Disk illumination by the variable X-ray corona contributes only a small fraction of the observed continuum lags. Our BLR models assume radiation-pressure-confined clouds distributed over a distance of 2–122 light days. We present calculated mean emissivity radii of many emission lines, and DC emission, and suggest a simple, transfer-function-dependent method that ties them to cross-correlation lag determinations. We do not find clear indications for large-optical-depth winds, but identify the signature of lower-column-density winds. In particular, we associate the shortest observed continuum lags with a combination of τ(1 Ryd) ≈ 2 wind and a partly shielded BLR. Even smaller optical depth winds may be associated with X-ray absorption features and with noticeable variations in the widths and lags of several high-ionization lines like He ii and C iv. Finally, we demonstrate the effect of torus dust emission on the observed lags in the i and z bands.
AB - The local (z = 0.0315) active galactic nucleus (AGN) Mrk 817 was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign, AGN STORM 2. Here, we present a comprehensive analysis of the broadband continuum variations using detailed modeling of the broad line region (BLR), several types of disk winds classified by their optical depth, and new numerical simulations. We find that diffuse continuum (DC) emission, with additional contributions from strong and broad emission lines, can explain the continuum lags observed in this source during high- and low-luminosity phases. Disk illumination by the variable X-ray corona contributes only a small fraction of the observed continuum lags. Our BLR models assume radiation-pressure-confined clouds distributed over a distance of 2–122 light days. We present calculated mean emissivity radii of many emission lines, and DC emission, and suggest a simple, transfer-function-dependent method that ties them to cross-correlation lag determinations. We do not find clear indications for large-optical-depth winds, but identify the signature of lower-column-density winds. In particular, we associate the shortest observed continuum lags with a combination of τ(1 Ryd) ≈ 2 wind and a partly shielded BLR. Even smaller optical depth winds may be associated with X-ray absorption features and with noticeable variations in the widths and lags of several high-ionization lines like He ii and C iv. Finally, we demonstrate the effect of torus dust emission on the observed lags in the i and z bands.
KW - Emission line galaxies
KW - Active galactic nuclei
KW - Reverberation mapping
KW - Galaxy accretion disks
KW - Supermassive black holes
UR - https://doi.org/10.48550/arXiv.2410.02652
U2 - 10.3847/1538-4357/ad8160
DO - 10.3847/1538-4357/ad8160
M3 - Article
SN - 0004-637X
VL - 976
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 59
ER -