The 3D shape of Type IIb SN 2011hs

Stevance, H. F.; Maund, Justyn R.; Baade, D.; Bruten, J. R.; Cikota, Aleksandar; Höflich, Peter; Wang, L; Wheeler, J. C.; Clocchiatti, A.; Spyromilio, J.; Patat, F.; Yang, Yi; Crowther, P. A.

doi:10.1093/mnras/stz265

Cited by 15 publications

(9 citation statements)

References 58 publications

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“…The presence of loops provides evidence for departures from a simple bi-axial (e.g. ellipsoidal; see Stevance et al 2019) configuration of the ejecta and is a natural consequence of mixing in a deflagration phase of burning, which is common to our model and the PDD models invoked by Stritzinger et al (2015).…”

Section: Signatures From the Explosionsupporting

confidence: 70%

White dwarf deflagrations for Type Iax supernovae: polarisation signatures from the explosion and companion interaction

Bulla

Liu

Röpke

et al. 2020

A&A

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Growing evidence suggests that Type Iax supernovae might be the result of thermonuclear deflagrations of Chandrasekhar-mass white dwarfs in binary systems. We carry out Monte Carlo radiative transfer simulations and predict spectropolarimetric features originating from the supernova explosion and subsequent ejecta interaction with the companion star. Specifically, we calculate viewing-angle dependent flux and polarisation spectra for a 3D model simulating the deflagration of a Chandrasekhar-mass white dwarf and, for a second model, simulating the ejecta interaction with a main-sequence star. We find that the intrinsic signal is weakly polarised and only mildly viewing-angle dependent, owing to the overall spherical symmetry of the explosion and the depolarising contribution of iron-group elements dominating the ejecta composition. The interaction with the companion star carves out a cavity in the ejecta and produces a detectable, but modest signal that is significant only at relatively blue wavelengths ( 5000 Å). In particular, increasingly fainter and redder spectra are predicted for observer orientations further from the cavity, while a modest polarisation signal P ∼ 0.2 per cent is found at blue wavelengths for orientations 30 • and 45 • away from the cavity. We find a reasonable agreement between the interaction model viewed from these orientations and spectropolarimetric data of SN 2005hk and interpret the maximum-light polarisation signal seen at blue wavelengths for this event as a possible signature of the ejecta-companion interaction. We encourage further polarimetric observations of SNe Iax to test whether our results can be extended and generalised to the whole SN Iax class.

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Section: Signatures From the Explosionsupporting

confidence: 70%

White dwarf deflagrations for Type Iax supernovae: polarisation signatures from the explosion and companion interaction

Bulla

Liu

Röpke

et al. 2020

A&A

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“…The optical and NIR spectra of SN 2020oi span days 2-67, and those of SN 2020bvc span days 1-73. The rest wavelengths of the lines (note that we use angstroms in STP air for the optical spectra and microns in vacuum for the NIR spectra) are from the SN spectral models by Dessart et al (2012) and synthesized spectra using SYNAPPS (Thomas et al 2011), other observed spectra of SNe Ic (Hunter et al 2009;Gerardy et al 2002;Drout et al 2016;Stevance et al 2017Stevance et al , 2019, or SNe Ib (Ergon et al 2014;Jencson et al 2017). The spectra of both SNe are dominated by atomic lines, in absorption or in emission, and sometimes simultaneously in the form of P Cygni profiles.…”

Section: Light Curves and Explosion Properties Of Sn 2020bvcmentioning

confidence: 99%

Near-infrared and Optical Observations of Type Ic SN 2020oi and Broad-lined Type Ic SN 2020bvc: Carbon Monoxide, Dust, and High-velocity Supernova Ejecta

Rho

Evans

Geballe

et al. 2021

ApJ

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We present near-IR (NIR) and optical observations of the Type Ic supernova (SN Ic) SN 2020oi in the galaxy M100 and the broad-lined SN Ic SN 2020bvc in UGC 9379, using Gemini, Las Cumbres Observatory, Southern Astrophysical Telescope, and other ground-based telescopes. The NIR spectrum of SN 2020oi at day 63 since the explosion shows strong CO emissions and a rising K-band continuum, which is the first unambiguous dust detection from an SN Ic. Non-LTE CO modeling shows that CO is still optically thick and that the lower limit to the CO mass is 10 −3 M e. The dust temperature is 810 K, and the dust mass is ∼10 −5 M e. We explore the possibilities that the dust is freshly formed in the ejecta, heated dust in the preexisting circumstellar medium, and an infrared echo. The light curves of SN 2020oi are consistent with a STELLA model with canonical explosion energy, 0.07 M e Ni mass, and 0.7 M e ejecta mass. A model of high explosion energy of 10 52 erg, 0.4 M e Ni mass, and 6.5 M e ejecta mass with the circumstellar matter reproduces the double-peaked light curves of SN 2020bvc. We observe temporal changes of absorption features of the IR Ca II triplet, S I at 1.043 μm, and Fe II at 5169 Å. The blueshifted lines indicate high velocities, up to 60,000 km s −1 for SN 2020bvc and 20,000 km s −1 for SN 2020oi, and the expansion velocity rapidly declines before the optical maximum. We present modeled spectral signatures and diagnostics of CO and SiO molecular bands between 1.4 and 10 μm.

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“…Since this is the first late-phase spectropolarimetric data for SLSNe-I, it is too early to draw the firm conclusions about the general ejecta geometry of SLSNe-I. Also, unfortunately, there are not many polarization data for normal stripped-envelope SNe (e.g., Tanaka et al 2012), in particular those with a good time series except for a few cases (Mauerhan et al 2015;Stevance et al 2017Stevance et al , 2019. Therefore, it is not easy to readily compare the geometry between normal stripped-envelope SNe and SLSNe-I in terms of polarization.…”

Section: Discussionmentioning

confidence: 96%

Late-phase Spectropolarimetric Observations of Superluminous Supernova SN 2017egm to Probe the Geometry of the Inner Ejecta

Saito

Tanaka

Moriya

et al. 2020

ApJ

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We present our spectropolarimetric observations of SN 2017egm, a Type I superluminous supernova (SLSN-I) in a nearby galaxy NGC 3191, with the Subaru telescope at +185.0 days after the g-band maximum light. This is the first spectropolarimetric observation for SLSNe at late phases. We find that the degree of the polarization in the late phase significantly changes from that measured at the earlier phase. The spectrum at the late phase shows a strong Ca emission line and therefore we reliably estimate the interstellar polarization (ISP) component assuming that the emission line is intrinsically unpolarized. By subtracting the estimated ISP, we find that the intrinsic polarization at the early phase is only ∼0.2%, which indicates an almost spherical photosphere, with an axial ratio ∼1.05. The intrinsic polarization at the late phase increases to ∼0.8%, which corresponds to the photosphere with an axial ratio ∼1.2. A nearly constant position angle of the polarization suggests the inner ejecta are almost axisymmetric. By these observations, we conclude that the inner ejecta are more aspherical than the outer ejecta. This may suggest the presence of a central energy source producing aspherical inner ejecta.

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The 3D shape of Type IIb SN 2011hs

Cited by 15 publications

References 58 publications

White dwarf deflagrations for Type Iax supernovae: polarisation signatures from the explosion and companion interaction

White dwarf deflagrations for Type Iax supernovae: polarisation signatures from the explosion and companion interaction

Near-infrared and Optical Observations of Type Ic SN 2020oi and Broad-lined Type Ic SN 2020bvc: Carbon Monoxide, Dust, and High-velocity Supernova Ejecta

Late-phase Spectropolarimetric Observations of Superluminous Supernova SN 2017egm to Probe the Geometry of the Inner Ejecta

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