Burning of a Hadronic Star into a Quark or a Hybrid Star

Abstract

We study the hydrodynamical transition from an hadronic star into a quark or a hybrid star. We discuss the possible mode of burning, using a fully relativistic formalism and realistic Equations of State in which hyperons can be present. We take into account the possibility that quarks form a diquark condensate. We also discuss the formation of a mixed phase of hadrons and quarks, and we indicate which region of the star can rapidly convert in various possible scenarios. An estimate of the final temperature of the system is provided. We find that the conversion process always corresponds to a deflagration and never to a detonation. Hydrodynamical instabilities can develop on the front. We estimate the increase in the conversion's velocity due to the formation of wrinkles and we find that, although the increase is significant, it is not sufficient to transform the deflagration into a detonation in essentially all realistic scenarios. Concerning convection, it does not always develop. In particular the system does not develop convection if hyperons are not present in the initial phase and if the newly formed quark phase is made of ungapped (or weakly gapped) quarks. At the contrary, the process of conversion from ungapped quark matter to gapped quarks always allows the formation of a convective layer. Finally, we discuss possible astrophysical implications of our results.

Strange Quark Stars in Binaries: Formation Rates, Mergers, and Explosive Phenomena

“…This is compatible with a combustion mode which is not driven by pressure but by diffusion (Olinto 1987) and is strongly accelerated by Rayleigh-Taylor hydrodynamical instabilities, as discussed in Horvath & Benvenuto (1988); Drago et al (2007); Herzog & Röpke (2011);Pagliara et al (2013); Drago & Pagliara (2015); Furusawa et al (2016). However, these instabilities halt below a certain critical density and the conversion of the most external layer is much slower, see also the recent simulations of Ouyed et al (2017).…”

Pulsar kicks by anisotropic neutrino emission from quark matter in strong magnetic fields

“…Drago et al (2007), where the energy release is about 3Δ 2 μ 2 q /π 2 and could accelerate the neutron star to 1000 km s −1 assuming μ q ∼ 450 MeV and Δ ∼ 20 MeV. The energy carried off by neutrinos would be ∼ Δ 2 /μ q per neutrino, which is in the range of 1 MeV and therefore small.…”

“…Also the neutrino mean free path will decrease due to the higher temperature that most probably will make it difficult to reach high velocities. In this connection it is interesting to study a scenario proposed by Drago et al (2007), where the authors discuss the transformation of a hadronic star into a quark star or a hybrid star. They find the formation of a convective layer in the case of conversion from ungapped (e.g.…”

Delta isobars in neutron stars

“…The process of conversion of a hadronic star into a quark star has been considered in many works, see for instance [40,[47][48][49][50][51][52]. Remarkably, the velocity of conversion is so high that in many studies, including detailed three-dimensional numerical simulations [52], almost the whole hadronic star is converted within a few milliseconds.…”

“…An interesting outcome of Refs. [40,49,52], is that the hydrodynamical combustion stops before the star is completely converted and in some cases few tenths of the initial mass remain unburnt. The subsequent conversion, driven most likely by neutrons and strange quarks diffusion across the interface separating the two phases, releases the rest of the combustion energy on a longer time scale.…”