A statistical study of the environmental age of core-collapse supernovae based on VLT/MUSE integral-field-unit spectroscopy

Abstract

We aim to understand the progenitor channels of CCSNe via a statistical study of the ages of their environments. We compiled a large and minimally biased sample of 129 CCSNe discovered by untargeted wide-field transient surveys and with archival VLT/MUSE integral-field-unit spectroscopy. We measured the local Hα luminosity within a 300-pc aperture centered on the SN explosion site as an empirical proxy for the environmental age. We find that the environments of Type II(P), IIb and Ib SNe do not show a significant age difference while Type Ic SNe are located in systematically younger environments than the other types (i.e. II $\approx$ IIb $\approx$ Ib > Ic). This is inconsistent with some previous reports of monotonically younger CCSNe environments with increasing envelope stripping (II > IIb > Ib > Ic). Our result suggests that Type Ic SNe have much younger and more massive progenitors than the other CCSN types and they likely originate from a distinct progenitor channel. The distinction between Types II(P), IIb and Ib SNe is insensitive to progenitor mass and mainly due to the different binary separation; in contrast, Type Ic SNe predominantly require much higher-mass progenitors accompanied by close companions with large mass ratios and/or much stronger stellar wind that depends sensitively on progenitor mass.

Figures (4)

• Figure 1: Example of the MUSE-based data products used in this work. Column 1: Pseudo-RGB composite of the host galaxy reconstructed from the MUSE datacube, where the RGB channels correspond to the cumulative fluxes in the spectral bands 6550--6750 Å (R), 4950--5150 Å (G), and 4750--4950 Å (B). Column 2: Continuum-subtracted nebular emission-line flux map shown on a logarithmic stretch; the colour scale is in arbitrary units. Column 3: Zoom-in on the local environment at the SN position; the black circle marks the 300 pc-radius circular aperture centred on the explosion site. Columns 4--5: Stacked spectrum extracted within this aperture, highlighting the H$\beta$ ($\sim$4861 Å; shown over the H$\beta$ region) and H$\alpha$ ($\sim$6563 Å; shown over the H$\alpha$ region) complexes, respectively. The spectrum has been corrected for the host-galaxy systemic redshift and is presented in the rest frame.
• Figure 2: CDFs of the local (300 pc aperture) H$\alpha$ luminosity for different CCSN types. The black curve shows the reference CDF constructed from all non-Ic (II(P)+IIb+Ib) events, while the grey shaded band denotes the 1$\sigma$, 2$\sigma$, and 3$\sigma$ uncertainty envelope derived from random resampling of the II(P)+IIb+Ib sample.
• Figure 3: Mean local (300 pc aperture) H$\alpha$ luminosity as a function of sample size. Data points: the observed sample size and mean $\log_{10} L_{\mathrm{H}\alpha}$ for each CCSN type; error bars are propagated from the individual H$\alpha$ luminosity measurement uncertainties. Reference distribution: shaded bands (dark and light) indicate the central 1$\sigma$ and 2$\sigma$ intervals of the mean values obtained by randomly drawing $N$ events from the full non-Ic ((II(P)+IIb+Ib)) CCSN sample, where $N$ is the sample size on the abscissa. The blue curve traces the corresponding mean of the resampled distributions.
• Figure 4: Heat map of pairwise $p$-values from two-sample goodness-of-fit tests comparing the CDFs of local (300 pc aperture) H$\alpha$ luminosities among CCSN types. The upper triangle reports the KS test $p$-values, while the lower triangle reports the AD test $p$-values.