Spectropolarimetry of the Type Ia supernova 2012fr

Maund, Justyn R.; Spyromilio, J.; Höflich, P.; Wheeler, J. C.; Baade, D.; Clocchiatti, A.; Patat, F.; Reilly, E.; Wang, L.; Zelaya, P.

doi:10.1093/mnrasl/slt050

Cited by 49 publications

(75 citation statements)

References 28 publications

(30 reference statements)

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“…(2) The nickel is concentrated in the center, while we are interested in the outer layers that are first to interact with the ISM. (3) The observed very low level continuum polarization at the first few weeks in SN 2012fr points to a symmetrical explosion that is inconsistent with the merger-induced explosion scenario (Maund et al 2013). Namely, it seems that explosion is not far from spherical from the beginning.…”

Section: A Low-mass Helium Wdmentioning

confidence: 92%

The response of a helium white dwarf to an exploding Type Ia supernova

Papish

Soker

Garcı́a–Berro

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We conduct numerical simulations of the interacting ejecta from an exploding CO white dwarf (WD) with a He WD donor in the double-detonation scenario for Type Ia supernovae (SNe Ia), and study the possibility of exploding the companion WD. We also study the long time imprint of the collision on the supernova remnant. When the donor He WD has a low mass, M WD = 0.2M ⊙ , it is at a distance of ∼ 0.08R ⊙ from the explosion, and helium is not ignited. The low mass He WD casts an 'ejecta shadow' behind it. By evolving the ejecta for longer times, we find that the outer parts of the shadowed side are fainter and its boundary with the ambient gas is somewhat flat. More massive He WD donors, M WD ≃ 0.4M ⊙ , must be closer to the CO WD to transfer mass. At a distance of a 0.045R ⊙ helium is detonated and the He WD explodes, leading to a triple detonation scenario. In the explosion of the donor WD approximately 0.15M ⊙ of unburned helium is ejected. This might be observed as a peculiar type Ib supernova.

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Section: A Low-mass Helium Wdmentioning

confidence: 92%

The response of a helium white dwarf to an exploding Type Ia supernova

Papish

Soker

Garcı́a–Berro

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…To the best of our knowledge this includes only SN 1986G (NGC 5128; Cen A), 2006X (NGC 4321;M100), 2008fp (ESO 428-G14), and the recent 2014J (NGC 3034; M 82). Other Type Ia SN have spectropolarimetric data: 1997dt, 2002bf, 2003du, 2004dt (Leonard et al 2005; 2001el (Wang et al 2003);2007sr (Zelaya et al 20132005ke (Patat et al 2012; 2011fe (Smith et al 2012); 2012fr (Maund et al 2013); however, the low reddening associated with these events makes the study of the interstellar polarization (ISP) wavelength dependence very uncertain, if not impossible (see also Zelaya et al, in prep. ).…”

Section: Datamentioning

confidence: 99%

Properties of extragalactic dust inferred from linear polarimetry of Type Ia Supernovae

Patat

Taubenberger

Cox

et al. 2015

A&A

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Aims. The aim of this paper is twofold: 1) to investigate the properties of extragalactic dust and compare them to what is seen in the Galaxy; 2) to address in an independent way the problem of the anomalous extinction curves reported for reddened Type Ia Supernovae (SN) in connection to the environments in which they explode. Methods. The properties of the dust are derived from the wavelength dependence of the continuum polarization observed in four reddened Type Ia SN: 1986G, 2006X, 2008fp, and 2014J. The method is based on the observed fact that Type Ia SN have a negligible intrinsic continuum polarization. This and their large luminosity makes them ideal tools to probe the dust properties in extragalactic environments.Results. All four objects are characterized by exceptionally low total-to-selective absorption ratios (R V ) and display an anomalous interstellar polarization law, characterized by very blue polarization peaks. In all cases the polarization position angle is well aligned with the local spiral structure. While SN 1986G is compatible with the most extreme cases of interstellar polarization known in the Galaxy, SN 2006X, 2008fp, and 2014J show unprecedented behaviours. The observed deviations do not appear to be connected to selection effects related to the relatively large amounts of reddening characterizing the objects in the sample. Conclusions. The dust responsible for the polarization of these four SN is most likely of interstellar nature. The polarization properties can be interpreted in terms of a significantly enhanced abundance of small grains. The anomalous behaviour is apparently associated with the properties of the galactic environment in which the SN explode, rather than with the progenitor system from which they originate. For the extreme case of SN 2014J, we cannot exclude the contribution of light scattered by local material; however, the observed polarization properties require an ad hoc geometrical dust distribution.

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“…A Pearson coefficient r calculated including all the points is reported. After being properly converted (see the text), spectropolarimetric data of normal SNe Ia (Wang et al 2007;Maund et al 2013) are also plotted for comparison (purple diamonds). Purple error bars mark the averaged uncertainties for these values.…”

Section: Degree Of Polarisation and Light Curve Propertiesmentioning

confidence: 99%

“…However, violent merger models have been called into question -particularly for normal SNe Ia -because they produce highly asymmetric ejecta that appear to be in contrast with the low level of polarisation typically observed (see Wang & Wheeler 2008, for a review). For instance, Maund et al (2013) recently obtained high-quality data for SN 2012fr at four different epochs and found that the polarisation was consistently below 0.1 per cent. They suggested that such low level of polarisation was inconsistent with the asymmetric 56 Ni distribution predicted by the violent merger model of Pakmor et al (2012).…”

Section: Introductionmentioning

confidence: 99%

Type Ia supernovae from violent mergers of carbon–oxygen white dwarfs: polarization signatures

Bulla

Pakmor

Kromer

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The violent merger of two carbon-oxygen white dwarfs has been proposed as a viable progenitor for some Type Ia supernovae. However, it has been argued that the strong ejecta asymmetries produced by this model might be inconsistent with the low degree of polarisation typically observed in Type Ia supernova explosions. Here, we test this claim by carrying out a spectropolarimetric analysis for the model proposed by Pakmor et al. (2012) for an explosion triggered during the merger of a 1.1 M and 0.9 M carbon-oxygen white dwarf binary system. Owing to the asymmetries of the ejecta, the polarisation signal varies significantly with viewing angle. We find that polarisation levels for observers in the equatorial plane are modest ( 1 per cent) and show clear evidence for a dominant axis, as a consequence of the ejecta symmetry about the orbital plane. In contrast, orientations out of the plane are associated with higher degrees of polarisation and departures from a dominant axis. While the particular model studied here gives a good match to highly-polarised events such as SN 2004dt, it has difficulties in reproducing the low polarisation levels commonly observed in normal Type Ia supernovae. Specifically, we find that significant asymmetries in the element distribution result in a wealth of strong polarisation features that are not observed in the majority of currently available spectropolarimetric data of Type Ia supernovae. Future studies will map out the parameter space of the merger scenario to investigate if alternative models can provide better agreement with observations.

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Spectropolarimetry of the Type Ia supernova 2012fr

Cited by 49 publications

References 28 publications

The response of a helium white dwarf to an exploding Type Ia supernova

The response of a helium white dwarf to an exploding Type Ia supernova

Properties of extragalactic dust inferred from linear polarimetry of Type Ia Supernovae

Type Ia supernovae from violent mergers of carbon–oxygen white dwarfs: polarization signatures

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