Boson stars in AdS spacetime

Abstract

We construct boson stars in global Anti de Sitter (AdS) space and study their stability. Linear perturbation results suggest that the ground state along with the first three excited state boson stars are stable. We evolve some of these solutions and study their nonlinear stability in light of recent work [1] arguing that a weakly turbulent instability drives scalar perturbations of AdS to black hole formation. However evolutions suggest that boson stars are nonlinearly stable and immune to the instability for sufficiently small perturbation. Furthermore, these studies find other families of initial data which similarly avoid the instability for sufficiently weak parameters. Heuristically, we argue that initial data families with widely distributed mass-energy distort the spacetime sufficiently to oppose the coherent amplification favored by the instability. From the dual CFT perspective our findings suggest that there exist families of rather generic initial conditions in strongly coupled CFT (with large number of degrees of freedom) that do not thermalize in the infinite future.

Collapse and revival in holographic quenches

“…The limiting line among these two situations is depicted in figure 3a. We observe that bouncing geometries are only obtained for quite small values of M [15,16,25]. Correspondingly, revivals in the dual CFT 3 happen for initial out of equilibrium states with an energy density per species clearly small compared to the system size.…”

“…Different aspects of scalar collapse in AdS d+1 have been studied in [15,[21][22][23][24][25][26]. We will focus here on how the time invested on the first bounce depends on the mass and thickness of the initial shell.…”

“…The minima of A m (t) correspond to the moments of maximal implosion of the matter shell and the maxima to its bounces against the AdS boundary, see figure 2. Following previous works [15,[21][22][23][24][25][26], we will consider a matter shell composed of a massless scalar field. The equations of motion for the system are [15] …”

Study of the nonlinear instability of confined geometries

“…Dias et al [10] have analyzed the full perturbative expansion and concluded that a resonant spectrum is indeed a necessary condition for collapse to occur at arbitrarily small amplitudes. Going beyond the perturbative level, some evidence exists that a nonresonant spectrum does halt collapse [6,11]. Nevertheless, we believe that the existing numerical evidence is circumstantial and wish to present a thorough analysis of this problem.…”

“…In a detailed analysis, they argued that except for special sets of initial data, the evolution of a massless, spherically symmetric scalar field always results in collapse to a BH. It has subsequently been suggested -with strong numerical and analytic evidence to support it -that not all initial conditions lead to collapse [6,7] (but see also [8]) but generic families of initial data remain that do collapse for arbitrarily small initial amplitudes 1 .…”