JWST Observations of SN 2024ggi II: NIRSpec Spectroscopy and CO Modeling at 285 and 385 Days Past the Explosion
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Mera, T. Ashall, C. Hoeflich, P. Medler, K. Shahbandeh, M. Burns, C. R. Baron, E. DerKacy, J. M. Morrell, N. Lu, J. Hinkle, J. T. Mazzali, P. A. Fereidouni, E. Pfeffer, C. M. Shiber, S. Temim, T. Galbany, L. Coulter, D. A. Ferrari, L. Hoogendam, W. B. Hsiao, E. Y. Phillips, M. M. Shappee, B. J. |
| author_facet | Mera, T. Ashall, C. Hoeflich, P. Medler, K. Shahbandeh, M. Burns, C. R. Baron, E. DerKacy, J. M. Morrell, N. Lu, J. Hinkle, J. T. Mazzali, P. A. Fereidouni, E. Pfeffer, C. M. Shiber, S. Temim, T. Galbany, L. Coulter, D. A. Ferrari, L. Hoogendam, W. B. Hsiao, E. Y. Phillips, M. M. Shappee, B. J. |
| contents | We present James Webb Space Telescope (JWST) NIRSpec observations of SN~2024ggi, spanning wavelengths of 1.7--5.5 micron at +285.51 and +385.27 days post-explosion. These nebular spectra are dominated by asymmetric emission lines from atomic species including H, Ca, Ar, C, Mg, Ni, Co, and Fe, indicative of an aspherical explosion. The other strong features are molecular CO vibrational bands from the fundamental and first overtone. We introduce a novel, data-driven approach using non-LTE 3D radiative transfer simulations to model the CO emission with high fidelity. This method enables us to constrain the three-dimensional CO distribution and its radial temperature structure. CO formation is found to occur prior to day +285, with subsequent evolution characterized by progressive evaporation. The CO mass decreases from approximately 8.7 to 1.3*E-3 Mo, while the average temperature drops from about 2900 K to 2500 K. Concurrently, the CO distribution transitions from nearly homogeneous to highly clumped (density contrast increasing from fc=1.2 to 2). The minimum velocity of the CO-emitting region remains nearly constant (v1 = 1200 to 1100 km/s), significantly above the receding photosphere velocity (v(ph) = 500 km/s), suggesting the photosphere resides within Si-rich layers. However, the temperature profile indicates that only a narrow zone reaches the conditions necessary for SiO formation. Due to a lack of observational constraints, SiO clumping is not modeled, and thus, synthetic SiO profiles for mass estimates are not highlighted. We discuss the implications of these findings for dust formation processes in SN~2024ggi. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_09600 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | JWST Observations of SN 2024ggi II: NIRSpec Spectroscopy and CO Modeling at 285 and 385 Days Past the Explosion Mera, T. Ashall, C. Hoeflich, P. Medler, K. Shahbandeh, M. Burns, C. R. Baron, E. DerKacy, J. M. Morrell, N. Lu, J. Hinkle, J. T. Mazzali, P. A. Fereidouni, E. Pfeffer, C. M. Shiber, S. Temim, T. Galbany, L. Coulter, D. A. Ferrari, L. Hoogendam, W. B. Hsiao, E. Y. Phillips, M. M. Shappee, B. J. Solar and Stellar Astrophysics We present James Webb Space Telescope (JWST) NIRSpec observations of SN~2024ggi, spanning wavelengths of 1.7--5.5 micron at +285.51 and +385.27 days post-explosion. These nebular spectra are dominated by asymmetric emission lines from atomic species including H, Ca, Ar, C, Mg, Ni, Co, and Fe, indicative of an aspherical explosion. The other strong features are molecular CO vibrational bands from the fundamental and first overtone. We introduce a novel, data-driven approach using non-LTE 3D radiative transfer simulations to model the CO emission with high fidelity. This method enables us to constrain the three-dimensional CO distribution and its radial temperature structure. CO formation is found to occur prior to day +285, with subsequent evolution characterized by progressive evaporation. The CO mass decreases from approximately 8.7 to 1.3*E-3 Mo, while the average temperature drops from about 2900 K to 2500 K. Concurrently, the CO distribution transitions from nearly homogeneous to highly clumped (density contrast increasing from fc=1.2 to 2). The minimum velocity of the CO-emitting region remains nearly constant (v1 = 1200 to 1100 km/s), significantly above the receding photosphere velocity (v(ph) = 500 km/s), suggesting the photosphere resides within Si-rich layers. However, the temperature profile indicates that only a narrow zone reaches the conditions necessary for SiO formation. Due to a lack of observational constraints, SiO clumping is not modeled, and thus, synthetic SiO profiles for mass estimates are not highlighted. We discuss the implications of these findings for dust formation processes in SN~2024ggi. |
| title | JWST Observations of SN 2024ggi II: NIRSpec Spectroscopy and CO Modeling at 285 and 385 Days Past the Explosion |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2510.09600 |