Rachid Ouyed, Jan E. Staff
We show that appealing to a Quark-Nova in a tight NS-WD binary system, a Type
Ia explosion can occur for a narrow range in white dwarf mass (0.5 < M_WD/M_sun
< 0.8). These CO WDs are heated by the strong QN shock triggering Carbon
burning under degenerate conditions (a QN-Ia). The explosion in our model
produces on average half the Nickel yield expected from Chandrasekhar-mass
counterparts. We find that Intermediate-Mass X-ray binaries (IMXBs) with donor
stars in the 3.5 < M_don./M_sun < 5 range are best candidates for QNe-Ia
progenitors. Specifically, IMXBs which evade the common envelope phase and
experience an extended accretion phase (preferably with the help of a
circumbinary disk), lead to optimum conditions for QNe-Ia. QNe-Ia are naturally
linked to star formation (with delays < 10^9 years). If the peak in star
formation rate occurred at 1 < z < 2 as observations seem to suggest, QN-Ia
rate would peak at 0.75 < z < 1.5, lurking among standard Type Ias. We estimate
that a small fraction of IMXBs experiencing a QN-Ia event is enough to make
them statistically significant at 0.75 < z < 1.5 in which case, their dimness
(by ~ 0.7 magnitudes as compared to their Chandrasekhar-mass counterparts)
would have consequences to Cosmology. In today's universe (z<0.75), and z>2
universe, we expect QNe-Ia to manifest themselves as rare sub-Chandrasekhar
Type Ias; most likely in star-forming galaxies.
View original:
http://arxiv.org/abs/1111.3053
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