Detection of circumstellar helium in Type Iax progenitor systems

Abstract

We present direct spectroscopic modeling of 44 Type Iax supernovae (SNe Iax) using spectral synthesis code SYNAPPS. We confirm detections of helium emission in the earlytime spectra of two SNe Iax: SNe 2004cs and 2007J. These He i features are better fit by a pure-emission Gaussian than by a P-Cygni profile, indicating that the helium emission originates from the circumstellar environment rather than the SN ejecta. Based on the modeling of the remaining 42 SNe Iax, we find no obvious helium features in other SN Iax spectra. However, ≈ 76% of our sample lack sufficiently deep luminosity limits to detect helium emission with a luminosity of that seen in SNe 2004cs and 2007J. Using the objects with constraining luminosity limits, we calculate that 33% of SNe Iax have detectable helium in their spectra. We examine 11 SNe Iax with late-time spectra and find no hydrogen or helium emission from swept up material. For latetime spectra, we calculate typical upper limits of stripped hydrogen and helium to be 2×10 −3 M and 10 −2 M , respectively. While detections of helium in SNe Iax support a white dwarf-He star binary progenitor system (i.e., a single-degenerate [SD] channel), non-detections may be explained by variations in the explosion and ejecta material. The lack of helium in the majority of our sample demonstrates the complexity of SN Iax progenitor systems and the need for further modeling. With strong independent evidence indicating that SNe Iax arise from a SD channel, we caution the common interpretation that the lack of helium or hydrogen emission at late-time in SN Ia spectra rules out SD progenitor scenarios for this class. (UCSC) (Jha 2017), all spectroscopically similar to the prototypical SN Iax, SN 2002cx (Li et al. 2003. As is the case for SNe Ia, the progenitor system and explosion mechanisms of SNe Iax are still unclear. Due to their spectroscopic agreement with SNe Ia near maximum light, SNe Iax are generally considered to be thermonuclear explosions that result from a white dwarf (WD) in a binary system. Based on stellar population estimates (Foley et al. 2009; McCully et al. 2014), SNe Iax are found

SN2019dge: A Helium-rich Ultra-stripped Envelope Supernova

“…Among the group of faint and fast objects, SN2005ek (Drout et al 2013), SN2010X (Kasliwal et al 2010), as well as some of the calcium-rich gap transients including PTF10iuv (Kasliwal et al 2012), iPTF16hgs (De et al 2018b), and SN2019ehk (Jacobson-Galán et al 2020;Nakaoka et al 2020) have been suggested as good candidates for ultra-stripped SNe (Moriya et al 2017). However, properties of these objects are also consistent with alternative interpretations, including corecollapse of stars with extended hydrogen-free envelopes (Kleiser & Kasen 2014;Kleiser et al 2018aKleiser et al , 2018b, and explosive detonation of a helium shell on the surface of white dwarfs (Shen et al 2010;Sim et al 2012;Jacobson-Galán et al 2019;Polin et al 2019;.…”

SN 2019muj – a well-observed Type Iax supernova that bridges the luminosity gap of the class

“…The model of SNe Iax originating from WD-He star systems is supported by the generally young ages of SNe Iax environments (Lyman et al 2018;Takaro et al 2020), though at least one SN Iax exploded in an elliptical galaxy (Foley et al 2010a). The detection of helium is also reported in the spectra of SNe 2004cs and 2007J (Foley et al 2013;Jacobson-Galán et al 2019;Magee et al 2019), but there is a debate on the real nature of these two objects (see White et al 2015;Foley et al 2016). Moreover, the apparent lack of helium in the majority of known SNe Iax (Magee et al 2019) shows the necessity of further investigation of this point.…”

Inlists and Output files for paper: Pre-Explosion Properties of Helium Star Donors to Thermonuclear Supernovae

“…However, a stripped mass of ≈ 3×10 −4 M was found in the simulation of Zeng et al (2020) who assumed a weak pure deflagration model. We also note that a limit of 2 × 10 −3 M is found for stripped H in SNe Iax (Jacobson-Galán et al 2019).…”