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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2510.21395 |
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| _version_ | 1866908610073722880 |
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| author | Landt, Hermine Boizelle, Benjamin D. Brotherton, Michael S. Ferrarese, Laura Fischer, Travis Gorjian, Varoujan Joner, Michael D. Kynoch, Daniel McLane, Jacob N. Mitchell, Jake A. J. Montano, John W. Riffel, Rogemar A. Sanmartim, David Storchi-Bergmann, Thaisa Ward, Martin J. Barth, Aaron J. Cackett, Edward M. De Rosa, Gisella Edelson, Rick Gelbord, Jonathan Homayouni, Yasaman Horne, Keith Kara, Erin A. Kriss, Gerard A. Arav, Nahum Bontà, Elena Dalla Dehghanian, Maryam Ferland, Gary J. Fian, Carina Buitrago, Diego H. González Ilić, Dragana Kaspi, Shai Kochanek, Christopher S. Kovačević, Andjelka B. Lewin, Collin Li, Yan-Rong Mehdipour, Missagh Netzer, Hagai Plesha, Rachel Popović, Luka Č. Proga, Daniel Wang, Jian-Min Zaidouni, Fatima Zu, Ying |
| author_facet | Landt, Hermine Boizelle, Benjamin D. Brotherton, Michael S. Ferrarese, Laura Fischer, Travis Gorjian, Varoujan Joner, Michael D. Kynoch, Daniel McLane, Jacob N. Mitchell, Jake A. J. Montano, John W. Riffel, Rogemar A. Sanmartim, David Storchi-Bergmann, Thaisa Ward, Martin J. Barth, Aaron J. Cackett, Edward M. De Rosa, Gisella Edelson, Rick Gelbord, Jonathan Homayouni, Yasaman Horne, Keith Kara, Erin A. Kriss, Gerard A. Arav, Nahum Bontà, Elena Dalla Dehghanian, Maryam Ferland, Gary J. Fian, Carina Buitrago, Diego H. González Ilić, Dragana Kaspi, Shai Kochanek, Christopher S. Kovačević, Andjelka B. Lewin, Collin Li, Yan-Rong Mehdipour, Missagh Netzer, Hagai Plesha, Rachel Popović, Luka Č. Proga, Daniel Wang, Jian-Min Zaidouni, Fatima Zu, Ying |
| contents | The AGN Space Telescope and Optical Reverberation Mapping 2 (STORM 2) campaign targeted Mrk 817 with intensive multi-wavelength 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 $\sim 90$ light-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 $\sim 6 \times 10^{44}$ 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 $\dot{m} \sim 0.2$. Alternatively, the dust is illuminated by an unobscured lower luminosity disk with $\dot{m} \sim 0.1$, 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 [SIII] $λ9531$ images. Its likely origin is in the compact bulge of the barred spiral host galaxy, where it is heated by a nuclear starburst. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_21395 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | AGN STORM 2. XI. Spectroscopic reverberation mapping of the hot dust in Mrk 817 Landt, Hermine Boizelle, Benjamin D. Brotherton, Michael S. Ferrarese, Laura Fischer, Travis Gorjian, Varoujan Joner, Michael D. Kynoch, Daniel McLane, Jacob N. Mitchell, Jake A. J. Montano, John W. Riffel, Rogemar A. Sanmartim, David Storchi-Bergmann, Thaisa Ward, Martin J. Barth, Aaron J. Cackett, Edward M. De Rosa, Gisella Edelson, Rick Gelbord, Jonathan Homayouni, Yasaman Horne, Keith Kara, Erin A. Kriss, Gerard A. Arav, Nahum Bontà, Elena Dalla Dehghanian, Maryam Ferland, Gary J. Fian, Carina Buitrago, Diego H. González Ilić, Dragana Kaspi, Shai Kochanek, Christopher S. Kovačević, Andjelka B. Lewin, Collin Li, Yan-Rong Mehdipour, Missagh Netzer, Hagai Plesha, Rachel Popović, Luka Č. Proga, Daniel Wang, Jian-Min Zaidouni, Fatima Zu, Ying Astrophysics of Galaxies Earth and Planetary Astrophysics Solar and Stellar Astrophysics The AGN Space Telescope and Optical Reverberation Mapping 2 (STORM 2) campaign targeted Mrk 817 with intensive multi-wavelength 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 $\sim 90$ light-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 $\sim 6 \times 10^{44}$ 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 $\dot{m} \sim 0.2$. Alternatively, the dust is illuminated by an unobscured lower luminosity disk with $\dot{m} \sim 0.1$, 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 [SIII] $λ9531$ images. Its likely origin is in the compact bulge of the barred spiral host galaxy, where it is heated by a nuclear starburst. |
| title | AGN STORM 2. XI. Spectroscopic reverberation mapping of the hot dust in Mrk 817 |
| topic | Astrophysics of Galaxies Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2510.21395 |