Serendipitous Nebular-phase JWST Imaging of SN Ia SN 2021aefx: Testing the Confinement of ⁵⁶Co Decay Energy

Abstract

We present new 0.3–21 μm photometry of SN 2021aefx in the spiral galaxy NGC 1566 at +357 days after B-band maximum, including the first detection of any Type Ia supernova (SN Ia) at >15 μm. These observations follow earlier JWST observations of SN 2021aefx at +255 days after the time of maximum brightness, allowing us to probe the temporal evolution of the emission properties. We measure the fraction of flux emerging at different wavelengths and its temporal evolution. Additionally, the integrated 0.3–14 μm decay rate of Δm 0.3–14 = 1.35 ± 0.05 mag/100 days is higher than the decline rate from the radioactive decay of 56Co of ∼1.2 mag/100 days. The most plausible explanation for this discrepancy is that flux is shifting to >14 μm, and future JWST observations of SNe Ia will be able to directly test this hypothesis. However, models predicting nonradiative energy loss cannot be excluded with the present data.

The JWST Resolved Stellar Populations Early Release Science Program. V. DOLPHOT Stellar Photometry for NIRCam and NIRISS

“…DOLPHOT is a well-tested, widely used, and publicly available package that already supports modules specific to several HST cameras (WFPC2; Advanced Camera for Surveys, hereafter ACS; WFC3/UVIS; and IR), has been a testing ground for the Roman Space Telescope, and includes general purpose routines that can be used on virtually any images of resolved stars. The addition of JWST modules will enable a wide array of JWST-specific and cross-facility (e.g., JWST and HST) science, some of which has already been demonstrated using early versions of our JWST DOLPHOT modules (e.g., Lee et al 2023Lee et al , 2024Chen et al 2023;Riess et al 2023;Van Dyk et al 2023;Warfield et al 2023;Li et al 2024;McQuinn et al 2024;Peltonen et al 2024).…”