Abstract
We present extensive multifrequency Karl G. Jansky Very Large Array (VLA) and Very Long Baseline Array (VLBA) observations of the radio-bright supernova (SN) IIb SN 2004C that span ∼40-2793 days post-explosion. We interpret the temporal evolution of the radio spectral energy distribution in the context of synchrotron self-absorbed 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 ∼0.06 c that carries an energy of ≈1049 erg. Our modeling further reveals a flat CSM density profile ρ CSM ∝ R −0.03±0.22 up to a break radius R br ≈ (1.96 ± 0.10) × 1016 cm, with a steep density gradient following ρ CSM ∝ R −2.3±0.5 at larger radii. We infer that the flat part of the density profile corresponds to a CSM shell with mass ∼0.021 M ☉, and that the progenitor’s effective mass-loss rate varied with time over the range (50-500) × 10−5 M ☉ 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.
| Original language | English (US) |
|---|---|
| Article number | 84 |
| Journal | Astrophysical Journal |
| Volume | 938 |
| Issue number | 1 |
| DOIs | |
| State | Published - Oct 1 2022 |
Funding
L.D. heartily thanks Avni Coda for her contribution to all data visualization and gratefully acknowledges the help of tablesgenerator.com for importing .csv files as LaTEX tables with minimal headache. The authors would like to thank the anonymous referee for constructive, thoughtful, and insightful comments. L.D. is grateful for the partial financial support of the IDEAS Fellowship, a research traineeship program funded by the National Science Foundation under grant DGE-1450006. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The Margutti team at UC Berkeley and Northwestern is supported in part by the National Science Foundation under grant Nos. AST-1909796 and AST-1944985, by the Heising-Simons Foundation under grant # 2018-0911. R.M. is a CIFAR Azrieli Global Scholar in the Gravity & the Extreme Universe Program 2019, and a Sloan Fellow in Physics, 2019. W.J.-G. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1842165. W.J.-G. acknowledges support through NASA grants in support of Hubble Space Telescope programs GO-16075 and 16500. D.M. acknowledges NSF support from grants PHY-1914448 and AST-2037297. Parts of this research was supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project No. CE170100013. Research at York University was supported by the Natural Sciences and Engineering Research Council of Canada. L.D. heartily thanks Avni Coda for her contribution to all data visualization and gratefully acknowledges the help of tablesgenerator.com for importing .csv files as L a TX tables with minimal headache. The authors would like to thank the anonymous referee for constructive, thoughtful, and insightful comments. L.D. is grateful for the partial financial support of the IDEAS Fellowship, a research traineeship program funded by the National Science Foundation under grant DGE-1450006. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The Margutti team at UC Berkeley and Northwestern is supported in part by the National Science Foundation under grant Nos. AST-1909796 and AST-1944985, by the Heising-Simons Foundation under grant # 2018-0911. R.M. is a CIFAR Azrieli Global Scholar in the Gravity & the Extreme Universe Program 2019, and a Sloan Fellow in Physics, 2019. W.J.-G. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1842165. W.J.-G. acknowledges support through NASA grants in support of Hubble Space Telescope programs GO-16075 and 16500. D.M. acknowledges NSF support from grants PHY-1914448 and AST-2037297. Parts of this research was supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project No. CE170100013. Research at York University was supported by the Natural Sciences and Engineering Research Council of Canada. E
Keywords
- Circumstellar matter
- Circumstellar shells
- Core-collapse supernovae
- Radio astronomy
- Stellar mass loss
- Supernovae
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science