Gravitational collapse with tachyon field and barotropic fluid

Abstract

A particular class of space-time, with a tachyon field, φ, and a barotropic fluid constituting the matter content, is considered herein as a model for gravitational collapse. For simplicity, the tachyon potential is assumed to be of inverse square form i.e., V (φ) ∼ φ −2 . Our purpose, by making use of the specific kinematical features of the tachyon, which are rather different from a standard scalar field, is to establish the several types of asymptotic behavior that our matter content induces. Employing a dynamical system analysis, complemented by a thorough numerical study, we find classical solutions corresponding to a naked singularity or a black hole formation. In particular, there is a subset where the fluid and tachyon participate in an interesting tracking behaviour, depending sensitively on the initial conditions for the energy densities of the tachyon field and barotropic fluid. Two other classes of solutions are present, corresponding respectively, to either a tachyon or a barotropic fluid regime. Which of these emerges as dominant, will depend on the choice of the barotropic parameter, γ. Furthermore, these collapsing scenarios both have as final state the formation of a black hole.

Semiclassical dynamics of horizons in spherically symmetric collapse

“…Therein, different fields, such as the standard scalar [14,15,21] or the tachyon [16,22], have been considered to play the role of the collapsing matter source. By employing the quantum gravity effects (such as the inverse triad correction imported from LQC), it was shown that the geometry of spacetime near the classical singularity is regular.…”

Einstein–Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

“…The well known and established CSK [78] theories can also be a starting point. 18 Nevertheless, the explicit presence of fermionic fields may not provide a simple enough setup to investigate the final outcome of a gravitational collapse. There are, however, other, perhaps more manageable scenarios.…”

“…Therefore, from determining the initial setting subject 17 With respect to the initial cosmological singularity, there seems to have been made more efforts in analyzing it when fermionic terms impose modifications to the classical equations (explicitly by means of fermionic degrees of freedom being present or induced by means of some averaged quantities); see e.g., ([88-100,128-130,132,133,166-169]). 18 A collapse setting was introduced in [170] where the non-minimal coupling of classical gravity to fermions results in the singularity avoidance.…”

“…The latter are classified as naked singularities, whose existence in GR has been established under a variety of specific circumstances and for different models, with matter content of various types, e.g. scalar fields [15][16][17][18], perfect fluids [19][20][21][22][23][24], imperfect fluids [25][26][27][28] and null strange quark fluids [29,30]. The analysis has also been taken to wider gravitational settings, such as f (R) theories [31], Lovelock gravity [32] (see also [33][34][35][36][37][38] for some recent reviews) and hypothesized quantum gravity theories .…”

The final state of gravitational collapse in Eddington‐inspired Born‐Infeld theory

“…[2] and references therein). The problem of collapsing scalar fields cosmologies, in the context of GR, has been studied in the literatures (see for example [36][37][38]). Therein, solutions corresponding to the black hole and naked singularity were found as possible collapse end states.…”