JWST NIRCam Observations of SN 1987A: Spitzer Comparison and Spectral Decomposition

TL;DR

The paper presents JWST NIRCam imaging of SN 1987A's remnant, revealing new outer ring features, confirming previous IR observations, and introducing spectral decomposition to distinguish emission sources.

Contribution

It introduces a spectral decomposition method to differentiate emission from the circumstellar medium and supernova ejecta using JWST NIRCam data.

Findings

Outer ER features are newly observed and spatially distinct.

Predicted brightness at 3.6 and 4.5 μm matches IRAC extrapolations.

Spectral decomposition effectively separates emission sources.

Abstract

JWST NIRCam observations at 1.5-4.5 $\mu$m have provided broad and narrow band imaging of the evolving remnant of SN 1987A with unparalleled sensitivity and spatial resolution. Comparing with previous marginally spatially resolved Spitzer IRAC observations from 2004-2019 confirms that the emission arises from the circumstellar equatorial ring (ER), and the current brightness at 3.6 and 4.5 $\mu$m was accurately predicted by extrapolation of the declining brightness tracked by IRAC. Despite the regular light curve, the NIRCam observations clearly reveal that much of this emission is from a newly developing outer portion of the ER. Spots in the outer ER tend to lie at position angles in between the well-known ER hotspots. We show that the bulk of the emission in the field can be represented by 5 standard spectral energy distributions (SEDs), each with a distinct origin and spatial distribution. This spectral decomposition provides a powerful technique for distinguishing overlapping emission from the circumstellar medium (CSM) and the supernova (SN) ejecta, excited by the forward and reverse shocks respectively.