Properties of Core Collapse Supernovae from Binary Population Synthesis

Abstract

Core collapse supernovae (CCSNe) impact many areas of astrophysics, including compact object formation and gravitational waves, but many uncertainties remain in our understanding of the evolution of their progenitors. We use the binary population synthesis code COSMIC to simulate populations of CCSNe across a wide range of metallicities and binary evolution assumptions. Our models vary the prescriptions for mass transfer stability, common envelope ejection efficiency, natal kick strength, and remnant mass-limited explodability to assess their impact on the resulting population of CCSNe. We find that reproducing the observed Type I to Type II rate requires either low common envelope efficiency or modified prescriptions for common envelope survival, highlighting the importance of stellar mergers in shaping the CCSN population. We further classify our synthetic CCSNe into subtypes and present their relative abundances using several different sets of classification criteria, highlighting the large uncertainties that persist in mapping progenitor properties to spectral classes. Finally, we present delay time distributions (DTDs) for our overall populations, separated into Type I and II, and into the full set of observed subtypes. Our DTDs show that models reproducing the observed Type I to Type II rate produce a larger fraction of late CCSNe than is expected under standard assumptions.

Figures (11)

• Figure 1: Ratio of Type I to Type II CCSNe across the metallicity range of our models. Each panel shows a different set of model variations: the maximum allowed remnant mass for single (dashed) and binary-inclusive (solid) populations (top left), the natal kick velocity dispersion $\sigma$ (top right), the common-envelope efficiency $\alpha$ (bottom left), and custom prescriptions for common-envelope evolution (bottom right). Data points from two surveys are shown for comparison: the LOSS survey as reported in LOSS (black squares) and the sample from KK12 (yellow hexagons). Both datasets are measured on the T04 metallicity scale T04, which we convert to $Z$ using the solar reference value of $12 + {\rm log(O/H)} = 9.0$. Grey shaded regions at $Z > 1.5\,Z_\odot$ mark metallicities beyond the upper limit of our COSMIC models.
• Figure 2: Stacked subtype fractions of Type II CCSNe across metallicity. The model shown follows the CEE prescriptions of Klencki2021, and only includes CCSNe forming small remnants ($M_{\rm rem}<3.0\,M_\odot$). The left and right panels apply the "branch IIn first" and "branch IIP first" classification schemes respectively (see Section \ref{['Classification method and variations II']}). Subtypes are colored as shown in the legend and stacked such that their sum is unity. The lower bound of the plot is raised to aid in viewing, since Type IIP CCSNe dominate the population.
• Figure 3: Stacked subtype fractions of Type I CCSNe across metallicity. The model shown follows the CEE prescriptions of Klencki2021, and only includes CCSNe forming small compact object remnants ($M_{\rm rem}<3.0\,M_\odot$) for all panels other than the lower right series. Each panel includes the observed Ib fraction from Shivvers2017, shown as a flat line across the metallicity range of the LOSS survey, with shaded regions indicating the associated uncertainty (the high-metallicity end extends beyond our models and is not shown, see Section \ref{['sec:Relative Rates']} for the treatment of metallicity comparison). The upper and lower left panels show the "absolute helium" and "mass transfer" classification schemes, respectively (see Section \ref{['Classification method and variations I']}). The upper right three panels show a sequence varying the ratio $M_{\rm ej,He}/M_{\rm ej}$, which defines classification in the "relative helium" scheme. The lower right sequence maintains the relative helium threshold of $M_{\rm ej,He}/M_{\rm ej}=0.43$ while varying the allowed maximum remnant mass.
• Figure 4: DTDs showing the remnant types of single-only and binary-inclusive populations. The model shown follows our fiducial binary evolution assumptions ($\sigma=265\,{\rm km\,s}^{-1}$, $\alpha=1$) and has metallicity $Z\approx Z_\odot$. The three panels along the top show only single stars, while the lower panels include both single and binary systems. Columns correspond to all CCSNe (left), Type I only (middle), and Type II only (right). Black outlines show the total DTD in each panel. Stacked histograms separate contributions from NSs ($M_{\rm rem}<3\,M_\odot$) and BHs ($3\,M_\odot<M_{\rm rem}<15\,M_\odot$).
• Figure 5: DTDs showing varied metallicity in single-only and binary-inclusive populations. The model shown follows our fiducial binary evolution assumptions ($\sigma=265\,{\rm km\,s}^{-1}$, $\alpha=1$) and spans ten metallicities evenly sampling our range. The three panels along the top show only single stars, while the lower panels include both single and binary systems. Columns correspond to all CCSNe (left), Type I only (middle), and Type II only (right). Only CCSNe forming remnants $M_{\rm rem}<15\,M_\odot$ are included.