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Failed Supernovae & Relativistic Jets In The SN 2010jp (PTF10aaxi) Event

30/12/2011

Type II supernovae events occur due to the irreversible gravitational collapse of the central Iron core of a massive star. To produce the enormous energetic release the outer material needs to be expelled outwards. Many theories, both corroboratory and contradictory, are presented on this core-bounce stage (Mueller & Hillebrandt 1981; Woosley & Weaver 1986; Ruben & Tuominen 1988; Sato et al. 1995; Dimmelmeier et al. 2002; Fryer & Warren 2004; Sekiguchi et al. 2005; Kotake et al. 2006; Couch et al. 2009). But what happens when the shock phase, which underpins the the core-bounce outburst model, stalls?

Many theoretical studies of the core-collapse mechanism suggest that breaking spherical symmetry may be an essential ingredient in overcoming this stalled shock and producing a successful supernova (SN) explosion (Blondin et al. 2003; Buras et al. 2006a, 2006b; Burrows et al. 2006, 2007). An extreme case of breaking spherical symmetry involves jet-driven explosions (Khokhlov et al. 1999; Wheeler et al. 2000; Hoflich et al. 2001; Maeda & Nomoto 2003; Couch et al. 2009). Strongly collimated jets that expel the surrounding stellar envelopes may arise from accretion onto newly-formed black holes as in the collapsar model (MacFadyen & Woosley 1999; MacFadyen et al. 2001), or by magnetohydrodynamic (MHD) mechanisms in the collapse and spin-down of highly magnetized and rapidly rotating neutron stars, or magnetars (LeBlanc & Wilson 1970; Bodenheimer & Ostriker 1974; Wheeler et al. 2000; Thompson et al. 2004; Bucciantini et al. 2006; Burrows et al. 2007; Komissarov & Barkov 2007; Dessart et al. 2008; Metzger et al. 2010; Piro & Ott 2011).

Some models present the idea of an outwardly acting nuetrino luminosity (Bethe & Wilson 1985), sometimes referred to as the neutrino-heating mechanism. Heating in the sense that the intense flux of neutrinos radiated from the nascent neutron star might deposit the energy needed to reverse the stellar collapse. The viability of this neutrino-heating mechanism has recently been demonstrated for stars near the lower mass end of SN progenitors (Kitaura et al. 2006; Janka et al. 2007a, 2007b, 2008). However, for high-mass stars ~25, this method has not been verified and some feel that is not viable for such scenarios. Hence, another mechanism is needed and is supplied in the form of a jet-driven explosion (MacFadyen et al. 2001 & Heger et al. 2003).

A recent study by Smith et al. (2012) focused on confirming the jet model by looking at a specific supernova event: SN 2010jp (a.k.a PTF10aaxi). They found that the spectra of SN2010jp displays a triple-peaked Hα profile corresponding to a narrow (FWHM > 800km s-1) central component that suggests strong shock interaction with a dense circumstellar medium (CSM); blue and red emission features centered at −12,600km s-1 and +15,400km s-1; and very broad wings extending from −22,000km s-1 to +25,000km s-1. Smith et al. (2012) found that these high-velocity features persist over multiple epochs during the 100 days after explosion, and that the features indicate a bipolar jet-driven explosion, with the central component produced by normal SN ejecta and CSM interaction at mid and low latitudes, while the high-velocity bumps and broad line wings arise in a non-relativistic bipolar jet. But, as ever, more study is needed to confirm the interpretation of the results presented by Smith et al. (2012)  are indeed correct.

The detection of a collimated jet in a Type II explosion is unprecedented. Models of jet-powered SNe have been published for fully stripped-envelope progenitors, which yield SNe Ibc and GRBs. Theoretical models also predict jet driven SNe II for a wide range of initial masses exceeding 25 (e.g., Heger et al. 2003), from collapsars that yield black holes. However, no clear case of a jet-driven SN II has yet been seen. For normal red supergiants (RSGs) with massive H envelopes, the general expectation is that that the collimated jet is largely destroyed while imparting its kinetic energy to a spherical envelope (Wheeler et al. 2002; Couch et al.2009). Hence, the evidence presented by Smith et al. (2012) is of significance to the future study of supernovae core-collapse events and GRBs.

Journal References:

  • MacFadyen, A. I.; Woosley, S. E. (1999) Collapsars: Gamma-Ray Bursts and Explosions In “Failed Supernovae”The Astrophysical Journal524 (1): pp. 262-289.
  • Heger, A. et al. (2003) How Massive Single Stars End Their LifeThe Astrophysical Journal591 (1): pp. 288-300.
  • Burrows, A. et al. (2006) A New Mechanism For Core-Collapse Supernova Explosions. The Astrophysical Journal, 640 (2): pp. 878-890.
  • Couch, S.M. et al. (2009) Aspherical Core-Collapse Supernovae In Red Supergiants Powered By Non-Relativistic JetsThe Astrophysical Journal, 696 (1): pp. 953-970.

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