Abstract Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf stars destabilized by mass accretion from a companion star 1 , but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds 2 or binary interaction 3 before explosion, and the supernova ejecta crashing into this nearby circumstellar material should result in radio synchrotron emission. However, despite extensive efforts, no type Ia supernova (SN Ia) has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate white dwarf star 4,5 . Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission and, for the first time in a SN Ia to our knowledge, a radio counterpart. On the basis of our modelling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star, an often proposed formation channel for SNe Ia (refs. 6,7 ). We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.
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Signatures of progenitors of Type Ia supernovae
Thermonuclear Supernovae (SNe Ia) are one of the building blocks of modern cosmology
and laboratories for the explosion physics of White Dwarf star/s (WD) in close binary
systems. The second star may be aWD(double degenerate systems, DD), or a non-degenerated
star (SD) with a main sequence star, red giant or a helium star as companion (Branch et al.
1995; Nomoto et al. 2003; Wang & Han 2012). Light curves and spectra of the explosion look
similar because a ’stellar amnesia’ (H¨oflich et al. 2006). Basic nuclear physics determines the
progenitor structure and the explosion physics, breaking the link between progenitor evolution,
and the explosion, resulting in three main classes of explosion scenarios: a) dynamical merging
of two WD and a heating on time scales of seconds (Webbink 1984; Isern et al. 2011),
b) surface helium detonations on top of a WD which ignite the central C/O by a detonation
wave traveling inwards (Nomoto 1982; Hoeflich & Khokhlov 1996; Kromer et al. 2010); c)
compressional heating in an accreting WD approaching the Chandrasekar mass on time of up
to 108 years which may originated from SD and DD systems (Whelan & Iben 1973; Piersanti
et al. 2003). Simulations of the explosions depend on the inital conditions at the onset of the
explosions, namely the mass and angular momentum of the WD(s). For all scenarios, diversity
in SNe Ia must be expected because the WD originates from a range of Main Sequence
masses (MMS < 8M ) and metallicities Z. Moreover, there is growing evidence that magnetic
fields B may have to be added to the ’mix’. Only with recent advances in observations ranging
from X-ray to radio, high precision spectroscopy, polarimetry and photometry and in the
time-domain astronomy we obtain constraints for progenitor, on the explosion scenarios and
links emerge between the progenitors and their environment with LCs and spectral signatures
needed for high precision cosmology. It is too early to give final answers but we present our
personal view. We will give some examples from the theory point of view and discuss future
prospects with upcoming ground based, ELT, GMT and space based such as JWST, Euclide
and WFIRST instruments.
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- Award ID(s):
- 1715133
- NSF-PAR ID:
- 10057612
- Date Published:
- Journal Name:
- Memorie della Società astronomica italiana
- Volume:
- 88
- ISSN:
- 0037-8720
- Page Range / eLocation ID:
- 302
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract We present a JWST/MIRI low-resolution mid-infrared (MIR) spectroscopic observation of the normal Type Ia supernova (SN Ia) SN 2021aefx at +323 days past rest-frame
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Abstract Observations of core-collapse supernovae (CCSNe) reveal a wealth of information about the dynamics of the supernova ejecta and its composition but very little direct information about the progenitor. Constraining properties of the progenitor and the explosion requires coupling the observations with a theoretical model of the explosion. Here we begin with the CCSN simulations of Couch et al., which use a nonparametric treatment of the neutrino transport while also accounting for turbulence and convection. In this work we use the SuperNova Explosion Code to evolve the CCSN hydrodynamics to later times and compute bolometric light curves. Focusing on Type IIP SNe (SNe IIP), we then (1) directly compare the theoretical STIR explosions to observations and (2) assess how properties of the progenitor’s core can be estimated from optical photometry in the plateau phase alone. First, the distribution of plateau luminosities (
L 50) and ejecta velocities achieved by our simulations is similar to the observed distributions. Second, we fit our models to the light curves and velocity evolution of some well-observed SNe. Third, we recover well-known correlations, as well as the difficulty of connecting any one SN property to zero-age main-sequence mass. Finally, we show that there is a usable, linear correlation between iron core mass andL 50such that optical photometry alone of SNe IIP can give us insights into the cores of massive stars. Illustrating this by application to a few SNe, we find iron core masses of 1.3–1.5M ⊙with typical errors of 0.05M ⊙. Data are publicly available online on Zenodo: doi:10.5281/zenodo.6631964 . -
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ABSTRACT The observed diversity in Type Ia supernovae (SNe Ia) – the thermonuclear explosions of carbon–oxygen white dwarf stars used as cosmological standard candles – is currently met with a variety of explosion models and progenitor scenarios. To help improve our understanding of whether and how often different models contribute to the occurrence of SNe Ia and their assorted properties, we present a comprehensive analysis of seven nearby SNe Ia. We obtained one to two epochs of optical spectra with Gemini Observatory during the nebular phase (>200 d past peak) for each of these events, all of which had time series of photometry and spectroscopy at early times (the first ∼8 weeks after explosion). We use the combination of early- and late-time observations to assess the predictions of various models for the explosion (e.g. double-detonation, off-centre detonation, stellar collisions), progenitor star (e.g. ejecta mass, metallicity), and binary companion (e.g. another white dwarf or a non-degenerate star). Overall, we find general consistency in our observations with spherically symmetric models for SN Ia explosions, and with scenarios in which the binary companion is another degenerate star. We also present an in-depth analysis of SN 2017fzw, a member of the subgroup of SNe Ia which appear to be transitional between the subluminous ‘91bg-like’ events and normal SNe Ia, and for which nebular-phase spectra are rare.
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Abstract Observational signatures of the circumstellar material (CSM) around Type Ia supernovae (SNe Ia) provide a unique perspective on their progenitor systems. The pre-supernova evolution of the SN progenitors may naturally eject CSM in most of the popular scenarios of SN Ia explosions. In this study, we investigate the influence of dust scattering on the light curves and polarizations of SNe Ia. A Monte Carlo method is constructed to numerically solve the process of radiative transfer through the CSM. Three types of geometric distributions of the CSM are considered: spherical shell, axisymmetric disk, and axisymmetric shell. We show that both the distance of the dust from the SN and the geometric distribution of the dust affect the light curve and color evolutions of SN. We found that the geometric location of the hypothetical circumstellar dust may not be reliably constrained based on photometric data alone, even for the best observed cases such as SN 2006X and SN 2014J, due to the degeneracy of CSM parameters. Our model results show that a time sequence of broadband polarimetry with appropriate time coverage from a month to about one year after explosion can provide unambiguous limits on the presence of circumstellar dust around SNe Ia.more » « less
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