Speaker
Description
The recent NICER observational data for the pulsars PSR J0030+0451 [1] and PSR J$0740+6620$ [2] impose new constrains in the mass-radius diagram of the corresponding compact star. Here, we investigate the possibility of such astrophysical object being a quark star. In particular, the quark matter is described by a holographic model with $N_c$ D3 branes and $N_f$ D7 probe branes, where $N_c$ and $N_f$ are the number of colors and flavors respectively [3]. For this top-down model, we determine the quark matter equation of state (EOS) and solve the Tolman-Oppenheimer-Volkoff (TOV) equations, obtaining the mass-radius diagram for a range of model parameters. In addition, we investigate dynamical astrophysical properties. For this end, we calculate the deformability parameter of a binary quark star system. The outcome is compared against the data of the GW170817 event detected by the LIGO-Virgo collaboration [4]. We present the range of parameters for which the model satisfies the LIGO-Virgo or the NICER astrophysical constraints. In particular, we show that it is not possible to satisfy simultaneously the LIGO-Virgo and the NICER constraints while considering quark stars composed of flavor-independent quark matter within the D3/D7 holographic model [5].
