早期近红外回波与IIn型超新星SN 2024kgi的时变质量损失历史
Early NIR echo and the time variable mass loss history of Type IIn SN 2024kgi
- Aryabhatta Research Institute of Observational Sciences（Aryabhatta观测科学研究所）
- Mahatma Jyotiba Phule Rohilkhand University（Mahatma Jyotiba Phule Rohilkhand大学）
- INAF - Osservatorio Astronomico di Padova（INAF-帕多瓦天文台）
- INAF - Osservatorio Astronomico di Brera（INAF-布雷拉天文台）
- Oskar Klein Centre, Department of Astronomy, Stockholm University（斯德哥尔摩大学奥斯特克·克莱因天文学中心）
- University of California, Davis（加州大学戴维斯分校）
- Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
对IIn型超新星SN 2024kgi的长期监测分析揭示了早期近红外回波和光变曲线转折，通过半解析建模估计出递增的CSM质量损失，支持双星相互作用起源。
AI中文摘要：
我们对IIn型超新星SN 2024kgi的长期测光和光谱监测活动进行了全面分析。该超新星在峰值时r波段绝对星等达到-19.81 ± 0.06等，热光度约为2 × 10^43 erg s^-1。我们在约第312天观测到光变曲线出现转折，此后光度下降从t^-1.0变为t^-4.5，这可能是由于激波扫过致密星周介质（CSM）所致。我们引入了一种针对瞬变事件中CSM相互作用的半解析光变曲线建模方法，该方法考虑了可变的扩散时间。因此，我们估计CSM质量为2.34^{+11.8}_{-1.6}太阳质量，密度轮廓为ρ_csm ∝ r^-2.74，表明在超新星爆发前质量损失逐渐增加。喷出物特征在约第80天出现宽的H、He和Ca II三重线，这比球对称CSM预期的要早得多，表明CSM存在不对称性。在光变曲线转折后，H线在红翼通量上表现出波长相关的亏损，表明在喷出物和/或激波后气体中形成了新的尘埃。我们从约第40天起观测到近红外（NIR）过量。我们将光变曲线转折前的早期NIR过量完全归因于预先存在的尘埃产生的近红外回波，因为没有其他迹象表明有新尘埃形成。晚期的NIR过量可能同时来自预先存在的尘埃和新形成的尘埃。质量损失的稳定增加、缓慢的CSM速度和不对称的CSM有利于双星相互作用引起的质量损失。
英文摘要：
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.
