Early NIR echo and the time variable mass loss history of Type IIn SN 2024kgi
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 ± 0.06 mag and a bolometric luminosity of ∼ 2 × 1043 erg s−1. We observe a break in the lightcurve at day ∼ 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⊙ and with a density profile ρcsm ∝ 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 ∼ 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 ∼ 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.
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BibTeX
@misc{dukiya2026early,
title = {{Early NIR echo and the time variable mass loss history of Type IIn SN 2024kgi}},
author = {Naveen Dukiya and Kuntal Misra and Andrea Pastorello and Andrea Reguitti and Anjasha Gangopadhyay and Aravind P. Ravi and Brian Hsu and Noah Franz and David J. Sand and Nathan Smith and Jennifer E. Andrews and Moira Andrews and K. Azalee Bostroem and Collin Christy and Monalisa Dubey and Joseph R. Farah and Archana Gupta and Estefania Padilla Gonzalez and Emily Hoang and D. Andrew Howell and Curtis McCully and Darshana Mehta and Megan Newsome and Jeniveve Pearson and Nicolas Meza Retamal and Jeonghee Rho and Manisha Shrestha and Bhagya Subrayan and Giacomo Terreran and Lina Tomasella and Stefano Valenti and Giorgio Valerin and Kathryn Wynn},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25233},
eprint = {2609.25233},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25233},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Early NIR echo and the time variable mass loss history of Type IIn SN 2024kgi
AU - Naveen Dukiya
AU - Kuntal Misra
AU - Andrea Pastorello
AU - Andrea Reguitti
AU - Anjasha Gangopadhyay
AU - Aravind P. Ravi
AU - Brian Hsu
AU - Noah Franz
AU - David J. Sand
AU - Nathan Smith
AU - Jennifer E. Andrews
AU - Moira Andrews
AU - K. Azalee Bostroem
AU - Collin Christy
AU - Monalisa Dubey
AU - Joseph R. Farah
AU - Archana Gupta
AU - Estefania Padilla Gonzalez
AU - Emily Hoang
AU - D. Andrew Howell
AU - Curtis McCully
AU - Darshana Mehta
AU - Megan Newsome
AU - Jeniveve Pearson
AU - Nicolas Meza Retamal
AU - Jeonghee Rho
AU - Manisha Shrestha
AU - Bhagya Subrayan
AU - Giacomo Terreran
AU - Lina Tomasella
AU - Stefano Valenti
AU - Giorgio Valerin
AU - Kathryn Wynn
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.25233
UR - https://arxiv.org/abs/2609.25233
AB - 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 ± 0.06 mag and a bolometric luminosity of ∼ 2 × 10^43 erg s^−1. We observe a break in the lightcurve at day ∼ 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_⊙ and with a density profile ρ_csm ∝ 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 ∼ 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 ∼ 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.
ER -