Hints of a second explosion (a quark nova) in Cassiopeia A supernova

Abstract

We show that the explosive transition of the neutron star (NS) to a quark star (QS) (a Quark Nova) in Cassiopeia A (Cas A) a few days following the SN proper can account for several of the puzzling kinematic and nucleosynthetic features observed. The observed decoupling between Fe and 44 Ti and the lack of Fe emission within 44 Ti regions is expected in the QN model owing to the spallation of the inner SN ejecta by the relativistic QN neutrons. Our model predicts the 44 Ti to be more prominent to the NW of the central compact object (CCO) than in the SE and little of it along the NE-SW jets, in agreement with NuStar observations. Other intriguing features of Cas A such as the lack of a pulsar wind nebula (PWN) and the reported a few percent drop of the CCO temperature over a period of 10 years are also addressed.

Frequency-dependent effects of gravitational lensing within plasma

“…The environments around these objects are expected to be complex, and some models explain magnetar-like behaviour through accretion from fall-back material on to the surface of the object (Ouyed, Leahy & Niebergal 2007). Interest in the quark nova scenario has grown considerably due in part to the NuSTAR observations of the Cassiopeia A supernova remnant (Grefenstette et al 2014) which detected a discrepancy in the distribution of titanium-44 and iron-56 abundances that can be explained by the quark nova scenario (Ouyed, Leahy & Koning 2015). Considerations of more realistic dispersion relations coupled with GR may be relevant in the dynamic environment around an energetic, highly compact quark star.…”

Superfluidity and Superconductivity in Neutron Stars

“…As a consequence, observations of Cassiopeia A put stringent constraints on the critical temperatures of the neutron superfluid and proton super-conductor in neutron-star cores [207,208,209]. However, this interpretation has been questioned and alternative scenarios have been proposed [210,211,212,213,214,215,216,217] (most of which still requiring superfluidity and/or superconductivity in neutron stars).…”

Quark-novae in binaries: Observational signatures and implications to astrophysics

“…We account for the luminosity 12 , the photometric/spectroscopic signatures 13 as well as introduce nuclear/spallation signatures resulting from the interaction of the ultra-relativistic QN ejecta with the SN shell and circumstellar material 14 . For shorter time-delays of less than a day, the QN kinetic energy is lost to PdV work but the collision between the r-process-rich QN ejecta with the SN ejecta yields unique nuclear signatures which may explain existing observations 15 . The QS shows features reminiscent of soft gamma repeaters 16,17 while the explosion energetics and variability are reminiscent of gamma-ray bursts 18 .…”

“…14 For shorter time-delays of less than a day, the QN kinetic energy is lost to PdV work but the collision between the r-process-rich QN ejecta with the SN ejecta yields unique nuclear signatures which may explain existing observations. 15 The QS shows features reminiscent of soft gamma repeaters 16,17 while the explosion energetics and variability are reminiscent of gamma-ray bursts.…”