Year: 2026
Type: preprint
Abstract: We present a comprehensive analysis of the long-term photometric and spectroscopic monitoring campaign of the Type IIn Supernova (SN) 2024kgi. The SN reaches at peak an $r$-band absolute magnitude of $-19.81 \pm 0.06$ mag and a bolometric luminosity of $\sim 2 \times 10^{43}$ erg s$^{-1}$. We observe a break in the lightcurve at day $\sim 312$, after which the luminosity decline changes from $t^{-1.0}$ to $t^{-4.5}$, likely due to the shock sweeping the dense CSM. We introduce a semi-analytical lightcurve modeling approach for CSM-interaction in transients that accounts for variable diffusion time. We hence estimate a CSM mass of $2.34^{+11.8}_{-1.6} M_{\odot}$ and with a density profile $ρ_{csm} \propto r^{-2.74}$, indicating progressively increasing mass loss toward the SN explosion. The ejecta signatures emerge as broad H, He, and Ca II triplet lines, at day $\sim 80$, much earlier than expected from a spherically symmetric CSM, suggesting asymmetry in the CSM. After the lightcurve break, the H lines exhibit a wavelength-dependent deficit in the red-wing flux, indicating new dust formation in the ejecta and/or in the post-shock gas. We observe an NIR excess from day $\sim 40$ onwards. We attribute the early NIR excess before the lightcurve break solely to the NIR echo from pre-existing dust, as there are no other indications for new dust formation. The late-time NIR excess likely has contributions from both the preexisting and newly formed dust. The steady increase in mass loss, slow CSM velocity, and asymmetric CSM favor a binary interaction-induced mass loss.
Source: arXiv (Cornell University)
Authors: Dukiya, Naveen, Misra, Kuntal, Pastorello, Andrea, Reguitti, Andrea, Gangopadhyay, Anjasha, Ravi, Aravind P., Hsu, Brian, Franz, Noah, Sand, David J., Smith, Nathan, Andrews, Jennifer E., Andrews, Moira, Bostroem, K. Azalee, Christy, Collin, Dubey, Monalisa, Farah, Joseph R., Gupta, Archana, Gonzalez, Estefania Padilla, Hoang, Emily, Howell, D. Andrew, McCully, Curtis, Mehta, Darshana, Newsome, Megan, Pearson, Jeniveve, Retamal, Nicolas Meza, Rho, Jeonghee, Shrestha, Manisha, Subrayan, Bhagya, Terreran, Giacomo, Tomasella, Lina, Valenti, Stefano, Valerin, Giorgio, Wynn, Kathryn
Institutions: M.J.P. Rohilkhand University, Aryabhatta Research Institute of Observational Sciences, University of California, Davis, University of Arizona, International Gemini Observatory, Las Cumbres Observatory Global Telescope Network, Johns Hopkins University, University of California, Santa Barbara, Seoul National University, Search for Extraterrestrial Intelligence, Adler Planetarium, Osservatorio Astronomico di Padova, National Institute for Astrophysics
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214101061
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