Type Ia supernovae inside planetary nebulae: shaping by jets
MNRAS 435, 320–328 (2013)
doi:10.1093/mnras/stt1301
Advance Access publication 2013 August 7
Type Ia supernovae inside planetary nebulae: shaping by jets
Danny Tsebrenko‹ and Noam Soker
Department of Physics, Technion – Israel Institute of Technology, Haifa 32000, Israel
Accepted 2013 July 14. Received 2013 July 1; in original form 2013 May 6
ABSTRACT
Key words: supernovae: individual: G299.2−2.9 – supernovae: individual: Kepler’s
SN – planetary nebulae: general – ISM: supernova remnants.
1 I N T RO D U C T I O N
Type Ia supernovae (SNe Ia) are thermonuclear detonations of
carbon–oxygen white dwarfs (WDs; Hoyle & Fowler 1960). Four
SN Ia scenarios are currently considered, with no consensus on
even the leading scenario for SN Ia. (a) The single degenerate (SD)
scenario (e.g. Whelan & Iben 1973; Nomoto 1982; Han & Podsiadlowski 2004). In this scenario, the WD accretes mass from a
non-degenerate stellar companion and explodes more or less when
it reaches the Chandrasekhar mass limit. (b) The double degenerate (DD) scenario (e.g. Iben & Tutukov 1984; Webbink 1984).
According to this scenario a merger of two WDs takes place, but
there is no specification of the later evolution, e.g. how long after
merger explosion occurs. Recent papers, for example, discuss violent merger and collision (e.g. Kushnir et al. 2013; Pakmor, Kromer
& Taubenberger 2013) as an ignition channel of the DD scenario.
(c) The core-degenerate (CD) scenario (e.g. Livio & Riess 2003;
Kashi & Soker 2011; Soker 2011; Ilkov & Soker 2012, 2013; Soker
et al. 2013). Here the WD merges with a hot core of a massive
asymptotic giant branch (AGB) star. Explosion might occur shortly
or a long time after merger. (d) The ‘double-detonation’ mechanism
(e.g. Woosley & Weaver 1994; Livne & Arnett 1995), in which a
sub-Chandrasekhar mass WD accumulates a layer of helium-rich
material on its surface. The helium layer detonates and leads to
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a second detonation near the centre of the CO WD (e.g. Shen,
Guillochon & Foley 2013 for a recent paper).
There is some overlap between these scenarios. In the violent
merger model (Pakmor et al. 2012), for example, it is possible that
in the merger process of the two WDs the helium is ignited first.
In this type of evolution, both the DD and the double detonation
operate (Pakmor et al. 2013). The double detonation might operate
in the CD scenario as well, with or without a violent merger. In both
the SD and the CD scenarios, a circumstellar shell can be formed
by ejecting the companion (to the WD) stellar envelope close to the
explosion time. A fraction of this mass might be accreted by the WD
through an accretion disc. Hence, the ejection of the envelope might
be accompanied by the formation of jets launched from an accretion
disc around the WD. In the SD scenario the disc is formed during
the mass accretion process on to the WD, while in the CD scenario
the disc is formed either around the core from the destructed WD
material, or around the WD from the destructed core. The formation
of a disc as a result of merger of two WDs was discussed before,
e.g. Raskin & Kasen (2013) and Ji et al. (2013) for recent papers.
Another possibility in the CD scenario is that the WD accretes
mass from the giant stellar envelope and launches two opposite
jets before merging with the giant’s core. Such circumstellar matter (CSM) shells are similar to some planetary nebulae (PNe), as
the central WD ionizes the CSM. When the SN is finally ignited,
the WD mass in the SD scenario and the merger product mass in
the CD scenario is expelled by the explosion at high velocities
of up to VSNm 20 000 km s−1 . If the explosion occurs within
C 2013 The Authors
Published by Oxford University Press on behalf of the Royal Astronomical Society
Using 3D numerical hydrodynamical simulations, we show that jets launched prior to Type Ia
supernova (SN Ia) explosion in the core-degenerate (CD) scenario can account for the appearance of two opposite lobes (‘Ears’) along the symmetry axis of the SN remnant (SNR). In the
double-degenerate (DD) and CD scenarios the merger of the two degenerate compact objects
is very likely to lead to the formation of an accretion disc, that might launch two opposite jets.
In the CD scenario, these jets interact with the envelope ejected during the preceding common
envelope phase. If explosion occurs shortly after the merger process, the exploding gas and
the jets will collide with the ejected nebula, leading to SNR with axisymmetric components
including ‘Ears’. We also explore the possibility that the jets are launched by the companion
white dwarf prior to its merger with the core. This last process is similar to the one where
jets are launched in some pre-planetary nebulae. The SNR ‘Ears’ in this case are formed by
a spherical SN Ia explosion inside an elliptical planetary nebula-like object. We compare our
numerical results with two SNRs – Kepler and G299.2−2.9.
Type Ia supernovae inside planetary nebulae
Figure 1. (a) The Kepler SNR. Merged image between 0.3 and 8 keV taken
from Reynolds et al. (2007). Note that our morphological interpretation of
the Kepler SNR is different by 90◦ than that of Burkey et al. (2013), who
take the equatorial plane to be where we take the symmetry axis on the figure
(dashed line). (b) G299−2.9 SNR. Merged image between 0.3 and 3 keV
taken from Park et al. (2007). Marked in both images are the observed lobelike features (‘Ears’), which we attribute to jets blown either a long time
before the explosion or immediately before the explosion.
2 NUMERICAL SETUP
The simulations are performed using the high-resolution multidimensional hydrodynamics code FLASH 4.0 (Fryxell et al. 2000). We
employ a full 3D uniform grid (all cells have the same size) with
Cartesian (x, y, z) geometry. In all runs the grid is a cube composed of
5123 cubical cells. The length of the axes is varied between the runs,
being = 0.65 pc in a run that focuses at early times, = 7.78 pc
in a run that studies the late evolution time and = 3.2 pc in all
other runs and tests. We use radiative cooling for solar metallicity
values, according to Sutherland & Dopita (1993), although radiative
cooling has a minor role in our simulations. The ejected material is
metal rich (see a recent paper by Park et al. 2013) and the cooling
of the shocked ejecta is expected to be more efficient than what the
cooling function mentioned above gives. However, this difference
in not significant for the duration of our simulations and does not
play a significant role in the shaping of the ‘Ears’.
There are two scenarios for forming various shapes of the CSM
during the stage prior to SN Ia explosion. In the SD scenario, the
WD grows in mass through accretion from a non-degenerate stellar
companion. If the companion is an evolved AGB star, it might blow
large parts of its envelope, as progenitors of PNe do. The accretion
on to the WD takes place via an accretion disc, which enables jets
to (...truncated)
