Fast spinning strange stars: possible ways to constrain interacting quark matter parameters

Abstract

For a set of equation of state (EoS) models involving interacting strange quark matter, characterized by an effective bag constant (B eff ) and a perturbative QCD corrections term (a 4 ), we construct fully general relativistic equilibrium sequences of rapidly spinning strange stars for the first time. Computation of such sequences is important to study millisecond pulsars and other fast spinning compact stars. Our EoS models can support a gravitational mass (M G ) and a spin frequency (ν) at least up to ≈ 3.0M ⊙ and ≈ 1250 Hz respectively, and hence are fully consistent with measured M G and ν values. This paper reports the effects of B eff and a 4 on measurable compact star properties, which could be useful to find possible ways to constrain these fundamental quark matter parameters, within the ambit of our EoS models. We confirm that a lower B eff allows a higher mass. Besides, for known M G and ν, measurable parameters, such as stellar radius, radius-to-mass ratio and moment of inertia, increase with the decrease of B eff . Our calculations also show that a 4 significantly affects the stellar rest mass and the total stellar binding energy. As a result, a 4 can have signatures in evolutions of both accreting and non-accreting compact stars, and the observed distribution of stellar mass and spin and other source parameters. Finally, we compute the parameter values of two important pulsars, PSR J1614-2230 and PSR J1748-2446ad, which may have implications to probe their evolutionary histories, and for constraining EoS models.

Strangeness in nuclei and neutron stars

“…The underlying model assumed in the simulations is the variational AP3 nucleonic EoS (red) [306]. The EoS models indicated in the figure are nucleonic (models AP3 and AP4) [306], but also schemes where the constituent species are quarks (u,d,s quarks) [361,362], nucleons and hyperons (inner core of hyperons, outer core of nucleonic matter) [363], or quarks and nucleons forming hybrid stars (inner core of uds quarks, outer core of nucleonic matter) [364]. The label CEFT indicates the range of a nucleonic EoS based on χEFT [365], whereas the pQCD is the range of nucleonic EoS that results from interpolating from CEFT at low densities and matching to perturbative QCD (pQCD) calculations at higher densities [366].…”

Millisecond radio pulsars with known masses: Parameter values and equation of state models

“…Note that previous authors explored the stable structure of compact stars, which provided general information about the fast spinning compact star parameters (e.g., Cook et al , 1994). Some authors went a step further, considered the measured spin rate of an ms pulsar, and computed a constant spin sequence for that pulsar (e.g., Datta et al , 1998;Bhattacharyya et al , 2016). But such a sequence gives large ranges of other parameter values for a given EoS model.…”

Dependence of pulsar death line on the equation of state

“…Assuming the thermal emission comes from the whole surface, we could set the smallest radius of the SSs at 4km in this work. The corresponding masses and moment of inertias are obtained by employing EoS named pMIT (Bhattacharyya et al 2016), CDDM1 and CDDM2 (Li et al 2016), which are shown in Table 2. For comparison, the mass of SSs are set as 0.03164M ⊙ , 0.02234M ⊙ , 0.01829M ⊙ , respectively (which is calculated from EoSs with R = 4km),…”

“…The radius and moment of inertia for the specific mass of SSs with EoSs named pMIT, CDDM1 and CDDM2. The EoS named pMIT are recovered from Bhattacharyya et al (2016), EoSs named CDDM1 and CDDM2 are get from Li et al (2016). The smallest mass is got with the best fit small radius of CCO.…”