Progenitors of Type IIb Supernovae. I. Evolutionary Pathways and Rates

Abstract

Type IIb supernovae (SNe) are important candidates to understand mechanisms that drive the stripping of stripped-envelope (SE) supernova (SN) progenitors. While binary interactions and their high incidence are generally cited to favor them as Type IIb SN progenitors, this idea has not been tested using models covering a broad parameter space. In this paper we use single-and binary-star models at solar and low metallicities covering a broad parameter space to investigate the progenitors of and evolutionary pathways to Type IIb SNe. We find that single and binary stars contribute roughly the same as Type IIb SNe at solar metallicity. Binary stars only dominate as progenitors at low metallicity. We also find that our models can account for less than half the observationally inferred rate for Type IIb SNe at high metallicity, making up < 4.5% of all core-collapse (CC) SNe. On the other hand, our models can account for the rates currently indicated by observations at low metallicity, making up 0.5 − 15% of all CC SNe. However, this requires low mass transfer efficiencies (∼ 0.1) to prevent most progenitors from entering contact. We suggest that the stellar wind mass-loss rates at solar metallicity used in our models are too high. Lower mass-loss rates would widen the parameter space for binary Type IIb SNe at solar metallicity by allowing stars that initiate mass transfer earlier in their evolution to reach CC without getting fully stripped.

Detection of the Red Supergiant Wind from the Progenitor of Cassiopeia A

“…WR stars have mass loss rates similar to red supergiants, but with winds speeds two orders of magnitude higher. However, the low mass of the progenitor is incompatible with a WR phase (Sravan et al 2019). In addition, hydrodynamical simulations of van Veelen et al (2009), showed the QSFs cannot be explained by a WR wind and the remnant's emission did not show evidence for remainders of a WR shell.…”

Progenitors of Type IIb Supernovae. II. Observable Properties

“…Comparison of these constraints with the full distribution of theoretical properties not only help ascertain the prevalence of observed properties in nature, but can also reveal currently unobserved populations. In this follow-up paper, we use the large grid of models presented in Sravan et al (2019) to derive distributions of single and binary SNe IIb progenitor properties and compare them to constraints from three independent observational probes: multi-band SN light-curves, direct progenitor detections, and X-ray/radio observations. Consistent with previous work, we find that while current observations exclude single stars as SN IIb progenitors, SN IIb progenitors in binaries can account for them.…”

“…In particular, our models indicate the existence of a group of highly stripped (envelope mass ∼ 0.1 − 0.2M ) progenitors that are compact (< 50R ) and blue (T eff 10 5 K) with ∼ 10 4.5 − 10 5.5 L and low density circumstellar mediums. As discussed in Sravan et al (2019), this group is necessary to account for SN IIb fractions and likely exist regardless of metallicity. The detection of the unobserved populations indicated by our models would support weak stellar winds and inefficient mass transfer in SN IIb progenitors.…”

SN 2017ivv: two years of evolution of a transitional Type II supernova

“…Woosley, Heger & Weaver 2002) and the fraction of SNe IIP is higher (e.g. Heger et al 2003;Woosley & Heger 2015;Sravan, Marchant & Kalogera 2019). At increased metallicity, mass-loss reduces the hydrogen envelope and only SNe IIL/IIb result (Heger et al 2003).…”