JWST Imaging of the Cartwheel Galaxy Reveals Dust Formation in SN 2021afdx

Griffin Hosseinzadeh, David J. Sand, Jacob E. Jencson, Jennifer E. Andrews, Irene Shivaei, K. Azalee Bostroem, Stefano Valenti, Tamás Szalai, Jamison Burke, D. Andrew Howell, Curtis McCully, Megan Newsome, Estefania Padilla Gonzalez, Craig Pellegrino, Giacomo Terreran

Published 2022-10-12Version 1

We present near- and mid-infrared (0.9-18 $\mu$m) photometry of supernova (SN) 2021afdx, which was imaged serendipitously with the James Webb Space Telescope (JWST) as part of its Early Release Observations of the Cartwheel Galaxy. Our ground-based optical observations show it is likely to be a Type IIb SN, the explosion of a yellow supergiant, and its infrared spectral energy distribution (SED) $\approx$200 days after explosion shows two distinct components, which we attribute to hot gas and warm dust in the SN ejecta. By fitting models of dust emission to the SED, we derive a lower limit on the dust mass of ${>}2.8 \times 10^{-3}\ M_\odot$, which is the highest yet observed in a Type IIb SN but consistent with other Type II SNe observed by the Spitzer Space Telescope. We also find that the radius of the dust is consistent with the radius of the ejecta, as derived from spectroscopic velocities during the photospheric phase, which could imply that the dust formed inside the ejecta. However, we cannot rule out an infrared echo off of pre-existing dust in the progenitor environment. Our results show the power of JWST to address questions of dust formation in SNe, and therefore the presence of dust in the early Universe, with much larger samples than have been previously possible.