LAUSR

Searches for supernovae (SNe) progenitors have relied on a direct detection of the star in fortuitous pre-explosion images. We propose an alternative method, using a combination of photometric stellar population fitting alongside integral-field-unit (IFU) spectroscopic analysis of the ionised gas to fully explore the SN environment and constrain the progenitor properties. Isochrone fitting of HST/WFC3 observations reveals the environment of iPTF13bvn contains two stellar populations with unique age (τ = log t years) and extinction (AV) values, with the closest agreement found between past progenitor studies of iPTF13bvn and our oldest stellar population (P2): $\tau _{P2}=6.97^{+0.06}_{-0.06}$, a corresponding initial mass Minitial, P2 = 20.0 M⊙ and $A_{V,P2}=0.53^{+0.10}_{-0.08}\, \textrm {mag}$. Further analysis with VLT/MUSE IFU-spectroscopic observations reveals no bright H ii regions associated with iPTF13bvn, suggesting no immediate ongoing star formation. Extinctions derived from the ionised gas are a minimum of ∼2.5 times higher than the resolved stellar population values, assisting in building a 3D picture of the environment. An analysis of the distribution of spaxel extinctions reveals increased variability in the environment of iPTF13bvn, on the edge of a spiral arm. Our study highlights the complex relationship between stars, gas and dust and how, when used in a holistic environmental analysis, they can begin to resolve degeneracies that have plagued past progenitor investigations. Specifically for iPTF13bvn, our results support a binary progenitor and a growing consensus for binarity as the predominant mass-loss mechanism for Type Ib SNe progenitors.