Time-Dependent Radiation Transport Simulations of Infrared Echoes from Dust-Shrouded Luminous Transients
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| Format: | Preprint |
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2025
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| author | Tuna, Semih Metzger, Brian D. Jiang, Yan-Fei White, Christopher J. |
| author_facet | Tuna, Semih Metzger, Brian D. Jiang, Yan-Fei White, Christopher J. |
| contents | A wide range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOT), can occur in dusty environments initially opaque to the transient's optical/UV light, becoming visible only once the dust is destroyed by the transient's rising luminosity. We present axisymmetric time-dependent radiation transport simulations of dust-shrouded transients with \texttt{Athena++} and tabulated gray opacities, which predict the light-curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light-curve depends on whether the transient rises rapidly or slowly compared to the light crossing-time of the photosphere, $t_{\rm lc}$. For slow-rising transients ($t_{\rm rise} \gg t_{\rm lc}$) such as SNe, the reprocessed IR radiation diffuses outwards through the dust shell faster than the sublimation front expands; the IR light-curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale $\sim t_{\rm rise}$ shorter than the transient duration. By contrast, for fast-rising transients ($t_{\rm rise} \ll t_{\rm lc}$) 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 (despite the dust photosphere having already being destroyed by peak light). 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2501_13157 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Time-Dependent Radiation Transport Simulations of Infrared Echoes from Dust-Shrouded Luminous Transients Tuna, Semih Metzger, Brian D. Jiang, Yan-Fei White, Christopher J. High Energy Astrophysical Phenomena Solar and Stellar Astrophysics A wide range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOT), can occur in dusty environments initially opaque to the transient's optical/UV light, becoming visible only once the dust is destroyed by the transient's rising luminosity. We present axisymmetric time-dependent radiation transport simulations of dust-shrouded transients with \texttt{Athena++} and tabulated gray opacities, which predict the light-curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light-curve depends on whether the transient rises rapidly or slowly compared to the light crossing-time of the photosphere, $t_{\rm lc}$. For slow-rising transients ($t_{\rm rise} \gg t_{\rm lc}$) such as SNe, the reprocessed IR radiation diffuses outwards through the dust shell faster than the sublimation front expands; the IR light-curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale $\sim t_{\rm rise}$ shorter than the transient duration. By contrast, for fast-rising transients ($t_{\rm rise} \ll t_{\rm lc}$) 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 (despite the dust photosphere having already being destroyed by peak light). 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. |
| title | Time-Dependent Radiation Transport Simulations of Infrared Echoes from Dust-Shrouded Luminous Transients |
| topic | High Energy Astrophysical Phenomena Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2501.13157 |