Radio Analysis of SN 2004C Reveals an Unusual CSM Density Profile as a Harbinger of Core Collapse
Lindsay DeMarchi, R. Margutti, J. Dittman, A. Brunthaler, D. Milisavljevic, Michael F. Bietenholz, C. Stauffer, D. Brethauer, D. Coppejans, K. Auchettl, K. D. A… 展开作者
Lindsay DeMarchi, R. Margutti, J. Dittman, A. Brunthaler, D. Milisavljevic, Michael F. Bietenholz, C. Stauffer, D. Brethauer, D. Coppejans, K. Auchettl, K. D. Alexander, C. D. Kilpatrick, Joe S. Bright, L. Z. Kelley, Michael C. Stroh, W. V. Jacobson-Galan
We present extensive multi-frequency VLA and VLBA observations of the radio-bright supernova (SN) IIb SN 2004C that span $\sim(40-2793)$ days post-explosion. We interpret the temporal evolution of the radio spectral energy distribution (SED) in the context of synchrotron self-absorbed (SSA) emission from the explosion's forward shock as it expands in the circumstellar medium (CSM) previously sculpted by the mass-loss history of the stellar progenitor. VLBA observations and modeling of the VLA data point to a blastwave with average velocity $\sim0.06c$ that carries an energy of $\sim 10^{49}$ erg. Our modeling further reveals a flat CSM density profile $ρ_{\rm{CSM}} \propto R^{-0.03 \pm0.22}$ up to a break radius $R_{br} \approx (1.96 \pm 0.10) \times 10^{16}$ cm, with a steep density gradient following $ρ_{\rm{CSM}} \propto R^{-2.3 \pm 0.5}$ at larger radii. We infer that the flat part of the density profile corresponds to a CSM shell with mass $\sim0.021 M_{\odot}$, and that the progenitor's effective mass-loss rate varied with time over the range $(50-500) \times 10^{-5} M_{\odot} \rm{yr}^{-1}$ for an adopted wind velocity $v_w =1000$ km $s^{-1}$ and shock microphysical parameters $ε_e = 0.1, ε_B = 0.01$. These results add to the mounting observational evidence for departures from the traditional single-wind mass-loss scenarios in evolved, massive stars in the centuries leading up to core collapse. Potentially viable scenarios include mass loss powered by gravity waves and/or interaction with a binary companion.
SN 2016iet: The Pulsational or Pair Instability Explosion of a Low Metallicity Massive CO Core Embedded in a Dense Hydrogen-Poor Circumstellar Medium
我们提出了SN 2016 iet的光学光度学和光谱学，这是一个前所未有的I型超新星（SN）在$z=0.0676$，在现有文献中没有明显的类似物。奇特的光变曲线有两个亮度大致相等的峰值（$\approx -19$ mag），相隔100天，随后在650个静止帧天内缓慢下降5 mag。光谱主要由钙和氧的发射线，只有$3400$公里的$^{-1}$的宽度，叠加在一个强大的蓝色连续在第一年，并与大比例的$L_{\rm [Ca\,II]}/L_{\rm [O\,I]}\approx 4$在晚些时候。没有明确的证据表明氢或氦在任何阶段与SN有关。我们模拟的光变曲线与几个潜在的能源：放射性衰变，中央引擎，和星周介质（CSM）的相互作用。不管模型如何，推断的祖细胞质量接近其寿命的终点（即，CO核质量）为$\gtrsim 55$ M $_\odot$，最大为$120$ M $_\odot$，将事件置于脉动对不稳定超新星（PPISNe）或对不稳定超新星（PISNe）的区域。CSM相互作用的模型为光变曲线和光谱提供了最一致的解释，并且要求CSM质量为$\approx 35$ M $_\odot$在爆炸前的最后十年中喷出。我们进一步发现SN 2016 iet与其低金属丰度矮宿主星系（$Z\approx 0.1$ Z $_\odot$，$M\approx 10^{8.5}$ M $_\odot$）的距离异常大…
Ground-based and JWST Observations of SN 2022pul: I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova
SN~2018erx: A fast-evolving, dust-reddened Type Icn supernova with broad C II emission lines
California Institute of Technology（加州理工学院）；Stockholm University（斯德哥尔摩大学）；Liverpool John Moores University（利物浦约翰摩尔斯大学）；Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)（天体物理学跨学科探索与研究中心）；University of Minnesota（明尼苏达大学）；Columbia University（哥伦比亚大学）；Flatiron Institute（平托研究所）；Weizmann Institute of Science（魏茨曼科学研究所）
