Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients
A range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOTs), can occur in dusty environments initially opaque to transients’ optical/UV light, becoming visible only once the dust is destroyed by transients’ rising luminosity. We...
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2025-01-01
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| author | Semih Tuna Brian D. Metzger Yan-Fei Jiang Christopher White |
| author_facet | Semih Tuna Brian D. Metzger Yan-Fei Jiang Christopher White |
| author_sort | Semih Tuna |
| collection | DOAJ |
| description | A range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOTs), can occur in dusty environments initially opaque to transients’ optical/UV light, becoming visible only once the dust is destroyed by transients’ rising luminosity. We present axisymmetric, time-dependent radiation transport simulations of dust-shrouded transients with Athena++ and tabulated gray opacities, predicting the light curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light curve depend on whether the transient rises rapidly or slowly compared to the light-crossing time of the photosphere, t _lc . For slow-rising transients ( t _rise ≫ t _lc ) like SNe, the reprocessed IR radiation diffuses outward through the dust shell faster than the shell sublimates; the IR light curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale ∼ t _rise shorter than the transient duration. By contrast, for fast-rising transients ( t _rise ≪ t _lc ) such as FBOTs and some TDEs, the finite light-travel time results in the reprocessed radiation arriving as an “echo” lasting much longer than the transient itself. We explore the effects of the system geometry by considering a torus-shaped distribution of dust. The IR light curves seen by observers in the equatorial plane of the torus resemble those for a spherical dust shell, while polar observers see faster-rising, brighter, and shorter-lived emission. We successfully model the IR excess seen in AT2018cow as a dust echo, supporting the presence of an opaque dusty medium surrounding FBOTs prior to explosion. |
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| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-ec9aa55b10f847aab00d997cf6eede652025-08-01T05:24:36ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198912710.3847/1538-4357/ade8edTime-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous TransientsSemih Tuna0https://orcid.org/0000-0002-2002-6860Brian D. Metzger1https://orcid.org/0000-0002-4670-7509Yan-Fei Jiang2https://orcid.org/0000-0002-2624-3399Christopher White3https://orcid.org/0000-0001-7448-4253Department of Physics and Columbia Astrophysics Laboratory, Columbia University , New York, NY 10027, USA ; semih.tuna@columbia.eduDepartment of Physics and Columbia Astrophysics Laboratory, Columbia University , New York, NY 10027, USA ; semih.tuna@columbia.edu; Center for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY 10010, USACenter for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY 10010, USACenter for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY 10010, USAA range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOTs), can occur in dusty environments initially opaque to transients’ optical/UV light, becoming visible only once the dust is destroyed by transients’ rising luminosity. We present axisymmetric, time-dependent radiation transport simulations of dust-shrouded transients with Athena++ and tabulated gray opacities, predicting the light curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light curve depend on whether the transient rises rapidly or slowly compared to the light-crossing time of the photosphere, t _lc . For slow-rising transients ( t _rise ≫ t _lc ) like SNe, the reprocessed IR radiation diffuses outward through the dust shell faster than the shell sublimates; the IR light curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale ∼ t _rise shorter than the transient duration. By contrast, for fast-rising transients ( t _rise ≪ t _lc ) such as FBOTs and some TDEs, the finite light-travel time results in the reprocessed radiation arriving as an “echo” lasting much longer than the transient itself. We explore the effects of the system geometry by considering a torus-shaped distribution of dust. The IR light curves seen by observers in the equatorial plane of the torus resemble those for a spherical dust shell, while polar observers see faster-rising, brighter, and shorter-lived emission. We successfully model the IR excess seen in AT2018cow as a dust echo, supporting the presence of an opaque dusty medium surrounding FBOTs prior to explosion.https://doi.org/10.3847/1538-4357/ade8edInfrared sourcesTransient sourcesHigh energy astrophysics |
| spellingShingle | Semih Tuna Brian D. Metzger Yan-Fei Jiang Christopher White Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients The Astrophysical Journal Infrared sources Transient sources High energy astrophysics |
| title | Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients |
| title_full | Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients |
| title_fullStr | Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients |
| title_full_unstemmed | Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients |
| title_short | Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients |
| title_sort | time dependent radiation transport simulations of infrared echoes from dust shrouded luminous transients |
| topic | Infrared sources Transient sources High energy astrophysics |
| url | https://doi.org/10.3847/1538-4357/ade8ed |
| work_keys_str_mv | AT semihtuna timedependentradiationtransportsimulationsofinfraredechoesfromdustshroudedluminoustransients AT briandmetzger timedependentradiationtransportsimulationsofinfraredechoesfromdustshroudedluminoustransients AT yanfeijiang timedependentradiationtransportsimulationsofinfraredechoesfromdustshroudedluminoustransients AT christopherwhite timedependentradiationtransportsimulationsofinfraredechoesfromdustshroudedluminoustransients |