TY - JOUR
T1 - AGN STORM 2. XI. Spectroscopic reverberation mapping of the hot dust in Mrk 817
AU - Landt, Hermine
AU - Boizelle, Benjamin D.
AU - Brotherton, Michael S.
AU - Ferrarese, Laura
AU - Fischer, Travis
AU - Gorjian, Varoujan
AU - Joner, Michael D.
AU - Kynoch, Daniel
AU - McLane, Jacob N.
AU - Mitchell, Jake A. J.
AU - Montano, John W.
AU - Riffel, Rogemar A.
AU - Sanmartim, David
AU - Storchi-Bergmann, Thaisa
AU - Ward, Martin J.
AU - Barth, Aaron J.
AU - Cackett, Edward M.
AU - Rosa, Gisella De
AU - Edelson, Rick
AU - Gelbord, Jonathan
AU - Homayouni, Yasaman
AU - Horne, Keith
AU - Kara, Erin A.
AU - Kriss, Gerard A.
AU - Arav, Nahum
AU - Bontà, Elena Dalla
AU - Dehghanian, Maryam
AU - Ferland, Gary J.
AU - Fian, Carina
AU - Buitrago, Diego H. González
AU - Ilić, Dragana
AU - Kaspi, Shai
AU - Kochanek, Christopher S.
AU - Kovačević, Andjelka B.
AU - Lewin, Collin
AU - Li, Yan-Rong
AU - Mehdipour, Missagh
AU - Netzer, Hagai
AU - Plesha, Rachel
AU - Popović, Luka Č.
AU - Proga, Daniel
AU - Wang, Jian-Min
AU - Zaidouni, Fatima
AU - Zu, Ying
N1 - Funding: H.L. acknowledges a Daphne Jackson Fellowship sponsored by the Science and Technology Facilities Council (STFC), UK, and financial support from STFC grants ST/P000541/1 and ST/T000244/1. The research by V.G. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (grant No. 80NM0018D0004). Research at UC Irvine was supported by NSF grant AST-1907290. J.A.J.M. acknowledges financial support from STFC studentship ST/S505365/1. M.J.W. acknowledges support of an Emeritus Fellowship award from the Leverhulme Trust (EM-2021-064). M.D. and G.F. acknowledge the support from JWST-AR-06419. 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), 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. thank the support by Chinese Academy of Sciences President’s International Fellowship Initiative (PIFI) for visiting scientists. C.S.K. is supported by National Science Foundation grants AST-2307385 and 2407206. Y.R.L. acknowledges financial support from the NSFC through grant No. 12273041 and from the Youth Innovation Promotion Association CAS.
PY - 2026/1/20
Y1 - 2026/1/20
N2 - The AGN Space Telescope and Optical Reverberation Mapping (STORM) 2 campaign targeted Mrk 817 with intensive multiwavelength monitoring and found its soft X-ray emission to be strongly absorbed. We present results from 157 near-IR spectra with an average cadence of a few days. Whereas the hot dust reverberation signal as tracked by the continuum flux does not have a clear response, we recover a dust reverberation radius of ∼90 lt-days from the blackbody dust temperature light curve. This radius is consistent with previous photometric reverberation mapping results when Mrk 817 was in an unobscured state. The heating/cooling process we observe indicates that the inner limit of the dusty torus is set by a process other than sublimation, rendering it a luminosity-invariant “dusty wall” of a carbonaceous composition. Assuming thermal equilibrium for dust optically thick to the incident radiation, we derive a luminosity of ∼6 × 1044 erg s−1 for the source heating it. This luminosity is similar to that of the obscured spectral energy distribution, assuming a disk with an Eddington accretion rate of ṁ ~ 0.2. Alternatively, the dust is illuminated by an unobscured lower luminosity disk with
ṁ ~ 0.1, which permits the UV–optical continuum lags in the high-obscuration state to be dominated by diffuse emission from the broad-line region. Finally, we find hot dust extended on scales ≳ 140–350 pc, associated with the rotating disk of ionised gas we observe in spatially resolved [S III] λ9531 images. Its likely origin is in the compact bulge of the barred spiral host galaxy, where it is heated by a nuclear starburst.
AB - The AGN Space Telescope and Optical Reverberation Mapping (STORM) 2 campaign targeted Mrk 817 with intensive multiwavelength monitoring and found its soft X-ray emission to be strongly absorbed. We present results from 157 near-IR spectra with an average cadence of a few days. Whereas the hot dust reverberation signal as tracked by the continuum flux does not have a clear response, we recover a dust reverberation radius of ∼90 lt-days from the blackbody dust temperature light curve. This radius is consistent with previous photometric reverberation mapping results when Mrk 817 was in an unobscured state. The heating/cooling process we observe indicates that the inner limit of the dusty torus is set by a process other than sublimation, rendering it a luminosity-invariant “dusty wall” of a carbonaceous composition. Assuming thermal equilibrium for dust optically thick to the incident radiation, we derive a luminosity of ∼6 × 1044 erg s−1 for the source heating it. This luminosity is similar to that of the obscured spectral energy distribution, assuming a disk with an Eddington accretion rate of ṁ ~ 0.2. Alternatively, the dust is illuminated by an unobscured lower luminosity disk with
ṁ ~ 0.1, which permits the UV–optical continuum lags in the high-obscuration state to be dominated by diffuse emission from the broad-line region. Finally, we find hot dust extended on scales ≳ 140–350 pc, associated with the rotating disk of ionised gas we observe in spatially resolved [S III] λ9531 images. Its likely origin is in the compact bulge of the barred spiral host galaxy, where it is heated by a nuclear starburst.
KW - Active galactic nuclei
KW - Quasars
KW - Dust continuum emission
KW - Dust physics
KW - Near infrared astronomy
U2 - 10.3847/1538-4357/ae17cd
DO - 10.3847/1538-4357/ae17cd
M3 - Article
SN - 0004-637X
VL - 997
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 22
ER -