2026ApJ...996..100C

The parameter space for mass loss in Type Ia supernova (SN Ia) progenitors is large, with different progenitor scenarios favoring different mass-loss regimes. Here we focus on the impact that uniform and isotropic outflows have on the circumstellar environment of SN Ia progenitors. We vary mass-loss rate, wind velocity, and outflow duration, and evolve supernova remnant (SNR) models in this grid of circumstellar structures in order to compare the bulk properties of these models (ages, radii, and Fe Kα centroids and luminosities) to observations. We find that roughly 55% (7/13) of young X-ray-bright Type Ia SNRs in the Milky Way and the Large Magellanic Cloud had progenitors that did not substantially modify their surroundings on ∼parsec scales. This group includes SN Ia with a range of luminosities, and at least one likely product of a double-detonation explosion in a sub-Chandrasekhar white dwarf (WD). The other half of our sample can be divided into two distinct classes. A small subset of SNRs (∼15%, 2/13) have large radii and low Fe Kα centroids and are likely expanding into large cavities that might have been excavated by fast (∼1000 km s^–1), sustained progenitor outflows. The majority of the SNRs that are expanding into a modified medium (∼30%, 4/13) show evidence for dense material, likely associated with slow (∼10 km s^–1) progenitor outflows, possibly a byproduct of accretion processes in near-Chandrasekhar WDs spawned by younger stellar populations.